Papers for Tuesday, Mar 26 2024

[...] We present a singlepulse search method, improving on commonly used neural network classifiers thanks to the filtering of radio frequency interference based on its spectral variance and the magnetar's rotation. With this approach, we were able to lower the signal to noise ratio (S/N) detection threshold from 8 to 5. This allowed us to find over 115,000 spiky single pulses - compared to 56,000 from the neutral network approach. Here, we present the temporal variation of the overall profile and single pulses. Two distinct phases of different single pulse activity can be identified: phase 1 from December 2018 to mid-2019, with a few single pulses per hour, and phase 2 from September 2020 with hundreds of single pulses per hour (with a comparable average flux density). We find that the single pulse properties and folded profile in phase 2 exhibit a change around mid-March 2021. Before this date, the folded profile consists of a single peak and single pulses, with fluences of up to 1000 Jyms and a single-peaked width distribution at around 10 ms. After mid-March 2021, the profile consists of a two peaks and the single pulse population shows a bimodal width distribution with a second peak at 1 ms and fluences of up to 500 Jyms. We also present asymmetries in the phase-resolved single pulse width distributions beginning to appear in 2020, where the pulses arriving earlier in the rotational phase appear wider than those appearing later. This asymmetry persists despite the temporal evolution of the other single pulse and emission properties. We argue that a drift in the emission region in the magnetosphere may explain this observed behaviour. Additionally, we find that the fluence of the detected single pulses depends on the rotational phase and the highest fluence is found in the centre of the peaks in the profile. [...]

Utilizing publicly available non-spinning eccentric binary black hole (BBH) merger simulations (\href{https://data.black-holes.org/waveforms/catalog.html}{https://data.black-holes.org/waveforms/catalog.html}) from the SXS collaboration~\cite{Hinder:2017sxy}, we present convincing evidence that the waveform phenomenology in eccentric BBH mergers is significantly simpler than previously thought. We find that the eccentric modulations in the amplitudes, phases, and frequencies in different spherical harmonic modes are all related and can be modeled using a single time series modulation. Using this universal eccentric modulation, we provide a model named \texttt{gwNRHME} to seamlessly convert a multi-modal (i.e with several spherical harmonic modes) quasi-circular waveform into multi-modal eccentric waveform if the quadrupolar eccentric waveform is known. This reduces the modelling complexity of eccentric BBH mergers drastically as we now have to model only a single eccentric modulation time-series instead of modelling the effect of eccentricity in all modes. When compared with the NR simulations, our model mismatches are mostly $\sim 10^{-3}$ and are comparable to the numerical errors in the NR simulations. Our method is modular and can be readily added to any quadrupolar non-spinning eccentric waveform model. We make our model publicly available through the \texttt{gwModels} (\href{https://github.com/tousifislam/gwModels}{https://github.com/tousifislam/gwModels}) waveform package.

We present the first volume-limited sample of spectroscopically confirmed hot subluminous stars out to 500 pc, defined using the accurate parallax measurements from the {\em Gaia} space mission data release 3 (DR3). The sample comprises a total of 397 members, with 305 ($\sim 77\%$) identified as hot subdwarf stars, including 83 newly discovered systems. Of these, we observe that 178 ($\sim58\%$) are hydrogen-rich sdBs, 65 are sdOBs ($\sim 21\%$), 32 are sdOs ($\sim 11\%$), and 30 are He-sdO/Bs ($\sim 10\%$). Among them, 48 ($\sim 16\%$) exhibit an infrared excess in their spectral energy distribution fits, suggesting a composite binary system. The hot subdwarf population is estimated to be 90\% complete, assuming that most missing systems are these composite binaries located within the main sequence (MS) in the \emph{Gaia} colour-magnitude diagram (CMD). The remaining sources in the sample include cataclysmic variables (CVs), blue horizontal branch stars (BHBs), hot white dwarfs (WDs), and MS stars. We derived the mid-plane density $\rho_{0}$ and scale height $\mathrm{h}_{z}$ for the non-composite hot subdwarf star population using a hyperbolic sechant profile (sech$^2$). The best-fit values are $\rho_{0}\,=\,5.17\pm 0.33 \times10^{-7}$ stars/pc$^{3}$ and $\mathrm{h}_{z} = 281 \pm 62$ pc. When accounting for the composite-colour hot subdwarfs and their estimated completeness, the mid-plane density increases to $\rho_{0}\,=\,6.15^ {+1.16}_{-0.53} \times10^{-7}$ stars/pc$^{3}$. This corrected space density is an order of magnitude lower than predicted by population synthesis studies, supporting previous observational estimates.

This is a review article for The Review of Particle Physics 2024 (aka the Particle Data Book), appearing as Chapter 25. It forms a compact review of knowledge of the cosmological parameters near the end of 2023. Topics included are Parametrizing the Universe; Extensions to the standard model; Probes; Bringing observations together; Outlook for the future.

Neutron star merger remnants are unique sites for exploring neutrino flavor conversion in dense media. Because of the natural excess of $\bar{\nu}_e$ over $\nu_e$, the neutrino-neutrino potential can cancel the matter potential, giving rise to matter-neutrino resonant flavor conversion. Under the assumption of two (anti)neutrino flavors and spatial homogeneity, we solve the neutrino quantum kinetic equations to investigate the occurrence of the matter-neutrino resonance within a multi-angle framework. We find that isotropy is broken spontaneously, regardless of the mass ordering. Relying on a hydrodynamical simulation of a binary neutron star merger remnant with a black hole of $3\ M_\odot$ and an accretion torus of $0.3\ M_\odot$, we find that complete flavor conversion caused by the matter-neutrino resonance is unlikely, although the matter and neutrino potentials cancel at various locations above the disk. Importantly, the matter-neutrino resonant flavor conversion crucially depends on the shape of the neutrino angular distributions. Our findings suggest that an accurate modeling of the neutrino angular distributions is necessary to understand flavor conversion physics in merger remnants, its implications on the disk physics and synthesis of the elements heavier than iron.

Unraveling the cosmological Li problem - the discrepancy between Big Bang nucleosynthesis predictions and observed values in the Spite plateau - requires a comprehensive exploration of stellar evolution. In this study, we utilized the code STAREVOL to compute the stellar evolution models with atomic diffusion, rotation-induced processes, parametric turbulence, and additional viscosity. We calibrated the models to fit the abundance of Li in Population II stars selected from the GALAH DR3 spectroscopic survey and literature compilation based on their chemical composition. The calibration reveals the significance of parametric turbulence in counteracting atomic diffusion effects. These models predict the constancy of the Spite plateau as a function of $T_\mathrm{eff}$ and [Fe/H] which agrees with the observational trend found after a detailed selection of dwarf non-peculiar stars. Other dwarfs that lie below the Spite plateau are either CEMP or have other types of chemical peculiarities, reinforcing the notion of their environmental origin. The Li abundance near the Spite plateau of the most Fe-deficient star, J0023+0307, which is not CEMP, provides additional evidence for the stellar depletion solution of the Li cosmological problem. Also, our models predict a transition from Li constancy at low metallicities to dispersion at high metallicities which is seen in observations. In addition, we extend our analysis to include a comparison with observational data from the globular cluster NGC 6752, showcasing excellent agreement between model predictions and Li and Mg trends in post-turnoff stars. This opens avenues for refining the estimates of initial Li abundance in metal-rich globular clusters which would help to constrain Li evolution in the Milky Way.

The presence of a large amount of Li in giants is still a mystery. Most of the super Li-rich giants reported in recent studies are in the solar metallicity regime. Here, we study the five metal-poor super Li-rich giants (SLRs) from GALAH Data Release 3 with their [Fe/H] ranging from -1.35 to -2.38 with lithium abundance of A(Li) $\geq$ 3.4~dex. The asteroseismic analysis reveals that none are on the red giant branch. The average period spacing ($\Delta P$ ) values indicate giants are in the core He-burning phase. All of them are low-mass giants (M $<$ 1.5M$_{\odot}$). The location in the HR diagram suggests one of them is in the red clump phase, and interestingly, the other four are much brighter and coincide with the early AGB phase. The abundance analysis reveals that C, O, Na, Ba, and Eu are normal for giants of respective metallicities and evolutionary phases. Further, we didn't find any strong evidence for the presence of dust in the form of infrared excess or binarity from the available radial velocity data. We discussed a few scenarios for the existence of SLRs at higher luminosity, including past merger events. The findings will help to understand the production and evolution of Li among giants, in particular, during and the post-red clump phase.

We examine the gamma-ray signal from dark matter (DM) annihilation from analogues of the Sagittarius (Sgr) dwarf spheroidal galaxy in the Auriga cosmological simulations. For velocity-dependent annihilation cross sections, we compute emissions from simulated Sgr subhalos and from the Milky Way (MW) foreground. In addition to the annihilation signals from DM particles bound to Sgr, we consider for the first time the annihilation of DM particles bound to the MW that overlap spatially with Sgr. For p-wave models this contribution can enhance the signal by over an order of magnitude, while for d-wave models the enhancement can be over two orders of magnitude. For Sommerfeld models, the corresponding emission decreases by up to nearly an order of magnitude. For Sommerfeld and s-wave models, the Sgr source can be visible above the MW foreground emission, while for p and d-wave models, the signal towards Sgr is most likely dominated by foreground MW emission. We interpret our results within the context of the observed gamma-ray emission from Sgr, finding that the templates from simulations likely have spatial morphology that is too extended to explain the point-like emission that is observed.

The envelopes and disks that surround protostars reflect the initial conditions of star and planet formation and govern the assembly of stellar masses. Characterizing these structures requires observations that span the near-infrared to centimeter wavelengths. Consequently, the past two decades have seen progress driven by numerous advances in observational facilities across this spectrum, including the \textit{Spitzer Space Telescope}, \textit{Herschel Space Observatory}, the Atacama Large Millimeter/submillimeter Array, and a host of other ground-based interferometers and single-dish radio telescopes. Nearly all protostars appear to have well-formed circumstellar disks that are likely to be rotationally-supported; the ability to detect a disk around a protostar is more a question of spatial resolution than whether or not a disk is present. The disks around protostars have inherently higher millimeter/submillimeter luminosities as compared to disks around more-evolved pre-main sequence stars, though there may be systematic variations between star forming regions. The envelopes around protostars are inherently asymmetric and streamers emphasize that mass flow through the envelopes to the disks may not be homogeneous. The current mass distribution of protostars may be impacted by selection bias given that it is skewed toward solar-mass protostars, inconsistent with the stellar initial mass function.

We present a self-consistent representation of the atmosphere and implement the interactions of light with the atmosphere using a photon Monte Carlo approach. We compile global climate distributions based on historical data, self-consistent vertical profiles of thermodynamic quantities, spatial models of cloud variation and cover, and global distributions of four kinds of aerosols. We then implement refraction, Rayleigh scattering, molecular interactions, Tyndall-Mie scattering to all photons emitted from astronomical sources and various background components using physics first principles. This results in emergent image properties that include: differential astrometry and elliptical point spread functions predicted completely to the horizon, arcminute-scale spatial-dependent photometry variations at 20 mmag for short exposures, excess background spatial variations at 0.2% due the atmosphere, and a point spread function wing due to water droplets. We reproduce the well-known correlations in image characteristics: correlations in altitude with absolute photometry (overall transmission) and relative photometry (spectrally-dependent transmission), anti-correlations of altitude with differential astrometry (non-ideal astrometric patterns) and background levels, and an anti-correlation in absolute photometry with cloud depth. However, we also find further subtle correlations including an anti-correlation of temperature with background and differential astrometry, a correlation of temperature with absolute and relative photometry, an anti-correlation of absolute photometry with humidity, a correlation of humidity with Lunar background, a significant correlation of PSF wing with cloud depth, an anti-correlation of background with cloud depth, and a correlation of lunar background with cloud depth.

Searches for helium in the exospheres of exoplanets via the metastable near-infrared triplet have yielded 17 detections and 40 non-detections. We performed a comprehensive re-analysis of published studies to investigate the influence of stellar XUV flux and orbital parameters on the detectability of helium in exoplanetary atmospheres. We identified a distinct 'orbital sweet spot' for helium detection, 0.03 to 0.08 AU from the host star, where the majority of detections occurred. This sweet spot is influenced by the stellar XUV flux and planet size. Notably, a lower ratio of XUV flux to mid-UV flux is preferred for planets compared to non-detections. We also found that helium detections occur for planets around stars with effective temperatures of 4400-6500 K, with a sharp gap at 5400 to 6000 K, where no detections occur. Additionally, our analysis of the cumulative XUV flux versus escape velocity shows planets with helium detections are found above the 'cosmic shoreline', suggesting the shoreline needs revision. The trends we found in our analysis contribute to a deeper understanding of exosphere evolution.

The Balmer decrement (H$\alpha$/H$\beta$) provides a constraint on attenuation, the cumulative effects of dust grains in the ISM. The ratio is a reliable spectroscopic tool for deriving the dust properties of galaxies that determine many different quantities such as star formation rate, metallicity, and SED models. Here we measure independently both the attenuation and H$\alpha$/H$\beta$ of an occulting galaxy pair: VV 191. Attenuation measurements in the visible spectrum (A$_{V,stars}$) from dust maps derived from the F606W filter of HST and the F090W filter of JWST are matched with spaxel-by-spaxel H$\alpha$/H$\beta$ observations from the George and Cynthia Mitchell Spectrograph (GCMS) of the McDonald Observatory. The 0.5 to 0.7 micron bandpass covers the Balmer lines for VV 191. The dust maps of JWST and HST provide the high sensitivity necessary for comparisons and tracking trends of the geometrically favorable galaxy. We present maps and plots of the Balmer lines for the VV 191 galaxy pair and for a specific region highlighting dust lanes for VV 191b in the overlap region. We compute A$_{V, HII}$ from H$\alpha$/H$\beta$ and plot both quantities against A$_{V, stars}$. Our results show that regions with higher dust content, residing closer to the spiral center, dominate ionized gas attenuation, leading to an overestimation of A$_{V, HII}$ by a factor or 2. Further out in the spiral arms, the lower dust content leads to more agreement between the attenuations, indicating lower SFR and larger contribution from older stars to the stellar continuum outside the Petrosian radius.

We analyse the radio-to-submillimetre spectral energy distribution (SED) for the central pseudobulge of NGC~1365 using archival data from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Array (VLA). This analysis shows that free-free emission dominates the continuum emission at 50--120~GHz and produces about 75 per cent of the 103~GHz continuum emission. However, the fraction of 103~GHz continuum emission originating from free-free emission varies significantly among different subregions in the pseudobulge, particularly for an outflow from the AGN on the eastern pseudobulge where the synchrotron emission produces half of the 103~GHz continuum emission. Free-free emission also dominates at 103~GHz within the central 400 pc diameter region, but this emission is associated with the AGN rather than star formation. The star formation rate (SFR) within the pseudobulge derived from the ALMA free-free emission is $8.9 \pm 1.1$~M$_\odot$~yr$^{-1}$. This is comparable to the SFR from the mid-infrared emission but higher than the SFR from the extinction-corrected H$\alpha$ line emission, mainly because the pseudobulge is heavily dust obscured. The 1.5 GHz emission yields a comparable SFR for the pseudobulge but may have lower SFRs within subregions of the pseudobulge because of the diffusion outside of these regions of the electrons producing the synchrotron radiation. We propose that applying a correction factor of 75 per cent to the 80--110~GHz continuum emission could provide valuable estimates of the free-free emission without performing any SED decomposition, which could derive extinction-free SFRs within 20 per cent accuracy.

One can infer the orbital alignment of exoplanets with respect to the spin of their host stars using the Rossiter-McLaughlin effect, thereby giving us the chance to test planet formation and migration theories and improve our understanding of the currently observed population. We analyze archival HARPS and HARPS-N spectroscopic transit time series of six gas giant exoplanets on short orbits, namely WASP-77 Ab, WASP-101b, WASP-103b, WASP-105b, WASP-120b and WASP-131b. We find a moderately misaligned orbit for WASP-101b ($\lambda =34\degree\ \pm$ 3) and a highly misaligned orbit for WASP-131b ($\lambda =161\degree\ \pm$ 5), while the four remaining ones appear aligned: WASP-77 Ab ($\lambda =-8\degree\ ^{+19}_{-18}$), WASP-103b ($\lambda =2\degree\ ^{+35}_{-36}$), WASP-105b ($\lambda =-14\degree\ ^{+28}_{-24}$), and WASP-120b ($\lambda =-2\degree\ \pm$ 4). For WASP-77 Ab, we were able to infer its true orbital obliquity ($\Psi =48\degree\ ^{+22}_{-21}$). We additionally perform transmission spectroscopy of the targets in search of strong atomic absorbers in the exoatmospheres, but are unable to detect any features, most likely due to the presence of high-altitude clouds or Rayleigh scattering muting the strength of the features. Finally, we comment on future perspectives for studying these targets with the upcoming space missions to investigate the evolution and migration histories of these planets.

We present a new cosmologically motivated mock redshift survey of the Dusty Star-Forming Galaxy population. Our mock survey is based on the Bolshoi-Planck dark-matter halo simulation and covers an area of 5.3 sq. degree. Using a semi-empirical approach, we generate a light cone and populate the dark-matter haloes with galaxies. Infrared properties are assigned to the galaxies based on theoretical and empirical relations from the literature. Additionally, background galaxies are gravitationally lensed by dark-matter haloes along the line-of-sight assuming a point-mass model approximation. We characterize the mock survey by measuring the star formation rate density, integrated number counts, redshift distribution, and infrared luminosity function. When compared with single-dish and interferometric observations, the predictions from our mock survey closely follow the compiled results from the literature. We have also directed this study towards characterizing one of the extragalactic legacy surveys to be observed with the TolTEC camera at the Large Millimeter Telescope: the 0.8 sq. degree Ultra Deep Survey, with expected depths of 0.025, 0.018 and 0.012 mJy beam$^{-1}$ at 1.1, 1.4 and 2.0 mm. Exploiting the clustering information in our mock survey, we investigate its impact on the effect of flux boosting by the fainter population of dusty galaxies, finding that clustering can increase the median boosting by 0.5 per cent at 1.1 mm, 0.8 per cent at 1.4 mm and, 2.0 per cent at 2.0 mm, and with higher dispersion.

The icy Galilean satellites display impact crater morphologies that are rare in the Solar System. They deviate from the archetypal sequence of crater morphologies as a function of size found on rocky bodies and other icy satellites: they exhibit central pits in place of peaks, followed by central dome craters, anomalous dome craters, penepalimpsests, palimpsests, and multi-ring structures. Understanding the origin of these features will provide insight into the geophysical factors that operate within the icy Galilean satellites. Pit craters above a size threshold feature domes. This trend, and the similarity in morphology between the two classes, suggests a genetic link between pit and dome craters. We propose that dome craters evolve from pit craters through topographic relaxation, facilitated by remnant heat from the impact. Our finite element simulations show that, for the specific crater sizes where we see domes on Ganymede and Callisto, domes form from pit craters within 10 Myr. Topographic relaxation acts to eliminate the stresses induced by crater topography and restore a flat surface: ice flows downwards from the rim and upwards from the crater depression driven by gravity. When the starting topography is a pit crater, the heat left over from the impact is concentrated below the pit. Since warm ice flows more rapidly, the upward flow is enhanced beneath the pit, leading to the emergence of a dome. Given the timescales and the dependence on heat flux, this model could be used to constrain the thermal history and evolution of these moons.

The Polarisation Sky Survey of the Universe's Magnetism (POSSUM) will conduct a sensitive $\sim$1 GHz radio polarization survey covering 20 000 square degrees of the Southern sky with the Australian Square Kilometre Array Pathfinder (ASKAP). In anticipation of the full survey, we analyze pilot observations of low-band (800-1087 MHz), mid-band (1316-1439 MHz), and combined-band observations for an extragalactic field and a Galactic-plane field (low-band only). Using the POSSUM processing pipeline, we produce prototype RM catalogs that are filtered to construct prototype RM grids. We assess typical RM grid densities and RM uncertainties and their dependence on frequency, bandwidth, and Galactic latitude. We present a median filter method for separating foreground diffuse emission from background components, and find that after application of the filter, 99.5% of measured RMs of simulated sources are within 3$\sigma$ of their true RM, with a typical loss of polarized intensity of 5% $\pm$ 5%. We find RM grid densities of 35.1, 30.6, 37.2, and 13.5 RMs per square degree and median uncertainties on RM measurements of 1.55, 12.82, 1.06, and 1.89 rad m$^{-2}$ for the median-filtered low-band, mid-band, combined-band, and Galactic observations, respectively. We estimate that the full POSSUM survey will produce an RM catalog of $\sim$775 000 RMs with median-filtered low-band observations and $\sim$877 000 RMs with median-filtered combined-band observations. We construct a structure function from the Galactic RM catalog, which shows a break at $0.7^{\circ}$, corresponding to a physical scale of 12-24 pc for the nearest spiral arm.

Enceladus is the Saturnian satellite known to have water vapor erupting from its south pole region called Tiger Stripes. Data collected by Cassini Ultraviolet Imaging Spectrograph during Enceladus transiting Saturn allow us to estimate water plume absorption from 1115.35 - 1912.50 Angstrom and compare it to the Mie solutions of Maxwell equations for particles with a diameter in the range from 10 nm up to 2 um. The best fit performed using Gradient Descent method indicates a presence of submicrometer particles of diameters: 120-180 nm and 240-320 nm consistent with Thermofilum sp., Thermoproteus sp., and Pyrobaculum sp. cell sizes present in hydrothermal vents on Earth.

We propose a possible quantum signature of the early Universe that could lead to observational imprints of the quantum nature of the inflationary period. Graviton production in the presence of an inflaton scalar field results in entangled states in polarization. This is because of a non-trivial effect due to the derivatives on two scalar fluctuations and it provides a fingerprint that depends on the polarization of the graviton that Alice and/or Bob measured in their patch. At horizon crossing, interactions between the gravitons and inflatons perform the required Bell experiments leading to a definitive measure. We hint how this signature could be measure in the high-order correlation function of galaxies, in particular on the halo bias and the intrinsic alignment.

We discuss the optical light curves of two Be X-ray Binaries, IGR J06074+2205 and SAX J2103.5+4545 recovered from the ATLAS, ZTF and ASAS-SN databases. Both sources show long term optical variability of 620 and 420 days respectively, with color redder when brighter. We suggest that this is due to the precession of the circumstellar disk. Another possibility is the propagation of a density wave in the disk. We remark that only these two sources show a large amplitude, periodic optical variability out of a sample of 16 well studied High Mass X-ray Binaries (HMXB) with a Main Sequence primary star.

Complementary metal-oxide-semiconductor (CMOS) detectors are a competitive choice for current and upcoming astronomical missions. To understand the performance variations of CMOS detectors in space environment, we investigate the total ionizing dose effects on custom-made large-format X-ray CMOS detectors. Three CMOS detector samples were irradiated with a Co-60 source with a total dose of 70 krad and 105 krad. We test and compare the performance of these detectors before and after irradiation. After irradiation, the dark current increases by roughly 20 to 100 times, and the readout noise increases from 3 e- to 6 e-. The bias level at 50 ms integration time decreases by 13 to 18 Digital Number (DN) at -30 degree. The energy resolution increases from about 150 eV to about 170 eV at 4.5 keV at -30 degree. The conversion gain of the detectors varies for less than 2% after the irradiation. Furthermore, there are about 50 pixels whose bias at 50 ms has changed by more than 20 DN after the exposure to the radiation and about 30 to 140 pixels whose readout noise has increased by over 20 e- at -30 degree at 50 ms integration time. These results demonstrate that the performances of large-format CMOS detectors do not suffer significant degeneration in space environment.

Although the study of X-ray binaries has led to major breakthroughs in high-energy astrophysics, their circumbinary environment at scales of $\sim$100--10,000 astronomical units has not been thoroughly investigated. In this paper, we undertake a novel and exploratory study by employing direct and high-contrast imaging techniques on a sample of X-ray binaries, using adaptive optics and the vortex coronagraph on Keck/NIRC2. High-contrast imaging opens up the possibility to search for exoplanets, brown dwarfs, circumbinary companion stars, and protoplanetary disks in these extreme systems. Here, we present the first near-infrared high-contrast images of 13 high-mass X-ray binaries located within $\sim$2--3 kpc. The key results of this campaign involve the discovery of several candidate circumbinary companions ranging from sub-stellar (brown dwarf) to stellar masses. By conducting an analysis based on galactic population models, we discriminate sources that are likely background/foreground stars and isolate those that have a high probability ($\gtrsim 60 - 99\%$) of being gravitationally bound to the X-ray binary. This publication seeks to establish a preliminary catalog for future analyses of proper motion and subsequent observations. With our preliminary results, we calculate the first estimate of the companion frequency and the multiplicity frequency for X-ray binaries: $\approx$0.6 and 1.8 $\pm$ 0.9 respectively, considering only the sources that are most likely bound to the X-ray binary. In addition to extending our comprehension of how brown dwarfs and stars can form and survive in such extreme systems, our study opens a new window to our understanding of the formation of X-ray binaries.

Intensity interferometry is a technique developed many decades ago, that has recently enjoyed a renaissance thanks in part to advances in photodetector technology. We investigate the potential for long-baseline optical intensity interferometry to observe bright, active galactic nuclei (AGN) associated with rapidly accreting supermassive black holes. We argue that realistic telescope arrays similar in area to existing Cherenkov arrays, if equipped with modern high-precision single photon detectors, can achieve a sufficiently high signal to noise ratio not only to detect distant AGN, but also to study them in great detail. We explore the science potential of such observations by considering two examples. First, we find that intensity interferometric observations of bright nearby AGN can allow detailed studies of the central accretion disks powering the AGN, allowing reconstruction of many disk properties like the radial profile. Next, we argue that intensity interferometers can spatially resolve the broad-line regions of AGN at cosmological distances, and thereby provide a geometric determination of the angular diameter distances to those AGN when combined with reverberation mapping. Since this measurement can be performed for AGN at distances of hundreds of megaparsecs, this directly measures the Hubble expansion rate $H_0$, with a precision adequate to resolve the recent Hubble tension. Finally, we speculate on future applications that would be enabled by even larger intensity interferometer arrays.

The formation of jets in black hole accretion systems is a long-standing problem. It has been proposed that a jet can be formed by extracting the rotation energy of the black hole ("BZ-jet") or the accretion flow ("disk-jet"). While both models can produce collimated relativistic outflows, neither has successfully explained the observed jet morphology. By employing general relativistic magnetohydrodynamic simulations, and considering nonthermal electrons accelerated by magnetic reconnection that is likely driven by magnetic eruption in the underlying accretion flow, we obtain images by radiative transfer calculations and compared them to millimeter observations of the jet in M87. We find that the BZ-jet originating from a magnetically arrested disk around a high-spin black hole can well reproduce the jet morphology, including its width and limb-brightening feature.

This paper explores the generation of primordial black holes (PBHs) and scalar-induced gravitational waves (SIGWs) from the inflation potential with a tiny bump. We propose a Lorentz function that makes a tiny bump characteristic of the inflation model potential. This property makes the scalar field move locally ultra slowly, which not only makes the primordial curvature power spectrum have $\mathcal{O}(10^{-2})$ peaks at a small scale but also satisfies observational constraints of the cosmic microwave background (CMB) on a large scale. Specifically, we calculate the abundances of PBHs for different mass ranges in this model, where PBHs with mass $10^{-12}M_\odot$ can make up almost all dark matter and PBHs with mass $10^{-5}M_\odot$ can explain OGLE ultrashort-timescale microlensing events. Moreover, we find that SIGWs accompanying the PBHs can be tested by the Square Kilometre Array (SKA), TianQin, Taiji, Laser Interferometer Space Antenna (LISA), and DECIGO. As for the parameter set I, the consequent SIGWs can explain the NANOGrav 12.5yrs signal.

We present the discovery of NGC253-SNFC-dw1, a new satellite galaxy in the remote stellar halo of the Sculptor Group spiral, NGC 253. The system was revealed using deep resolved star photometry obtained as part of the Subaru Near-Field Cosmology Survey that uses the Hyper Suprime-Cam on the Subaru Telescope. Although rather luminous ($\rm{M_{V}} = -11.7 \pm 0.2$) and massive ($M_* \sim 1.25\times 10^7~\rm{M}_{\odot}$), the system is one of the most diffuse satellites yet known, with a half-light radius of $\rm{R_{h}} = 3.37 \pm 0.36$ kpc and an average surface brightness of $\sim 30.1$ mag arcmin$^{-2}$ within the $\rm{R_{h}}$. The colour-magnitude diagram shows a dominant old ($\sim 10$ Gyr) and metal-poor ($\rm{[M/H]}=-1.5 \pm 0.1$ dex) stellar population, as well as several candidate thermally-pulsing asymptotic giant branch stars. The distribution of red giant branch stars is asymmetrical and displays two elongated tidal extensions pointing towards NGC 253, suggestive of a highly disrupted system being observed at apocenter. NGC253-SNFC-dw1 has a size comparable to that of the puzzling Local Group dwarfs Andromeda XIX and Antlia 2 but is two magnitudes brighter. While unambiguous evidence of tidal disruption in these systems has not yet been demonstrated, the morphology of NGC253-SNFC-dw1 clearly shows that this is a natural path to produce such diffuse and extended galaxies. The surprising discovery of this system in a previously well-searched region of the sky emphasizes the importance of surface brightness limiting depth in satellite searches.

Radio galaxies in clusters of galaxies are prominent reservoirs of magnetic fields and of non-thermal particles, which get mixed with the intracluster medium. We review the observational and theoretical knowledge of the role of these crucial ingredients for the formation of diffuse radio emission in clusters (radio halos, relics, mini halos) and outline the open questions in this field.

Galaxies' stellar masses, gas-phase oxygen abundances (metallicity), and star formation rates (SFRs) obey a series of empirical correlations, most notably the mass-metallicity relation (MZR) and fundamental metallicity relation (FZR), which relates oxygen abundance to a combination of stellar mass and SFR. However, due to the difficulty of measuring oxygen abundances and SFRs in galaxies that host powerful active galactic nuclei (AGN), to date it is unknown to what extent AGN-host galaxies also follow these correlations. In this work, we apply Bayesian methods to the MaNGA integral field spectrographic (IFS) survey that allow us to measure oxygen abundances and SFRs in AGN hosts, and use these measurements to explore how the MZR and FZR differ between galaxies that do and do not host AGN. We find similar MZRs at stellar masses above $10^{10.5} \mathrm{M}_\odot$, but that at lower stellar masses AGN hosts show up to $\sim 0.2$ dex higher oxygen abundances. The offset in the FZR is significantly smaller, suggesting that the larger deviation in the MZR is a result of AGN-host galaxies having systematically lower SFRs at fixed stellar mass. However, within the AGN-host sample there is little correlation between SFR and oxygen abundance. These findings support a scenario in which an AGN can halt efficient gas accretion, which drives non-AGN host galaxies to both higher SFR and lower oxygen abundance, resulting in the galaxy evolving off the star-forming main sequence (SFMS). As a consequence, as the SFR declines for an individual system its metallicity remains mostly unchanged.

We search for possible pulsar TeV halos among the very-high-energy (VHE) sources reported in different VHE surveys, among which in particular we use the results from the first Large High Altitude Air Shower Observatory (LHAASO) catalog of $\gamma$-ray sources. Six candidates are found. They share the properties of containing a middle-aged, gamma-ray--bright pulsar in their positional error circles (the respective pulsars are J0248+6021, J0359+5414, J0622+3749, J0633+0632, J2006+3102, and J2238+5903), being in a rather clean field without any common Galactic VHE-emitting supernova remnants or (bright) pulsar wind nebulae (PWNe), and showing the absence of any gamma-ray emissions in 0.1--500\,GeV after removing the pulsars' emissions. Combining with several (candidate) TeV halos reported, we find nearly the same relations as previously ones between their luminosities at 50\,TeV, $L_{\rm 50TeV}$, and the corresponding pulsars' spin-down luminosities, $\dot{E}$, which are $L_{\rm 50TeV}\sim \dot{E}^{0.9}$ and $L_{\rm 50TeV}/\dot{E}\sim 6.4\times 10^{-4}$. We probe possible connections between the extension sizes of the VHE sources and the pulsars' ages, and find a weak trend of being older and smaller. By comparing to the VHE detection results for PWNe, it is clear to see that the (candidate) TeV halos have hard emissions by having their power-law indices smaller than 2 in 1--25\,TeV or only being detected in 25--100\,TeV. In addition, we also consider other seven VHE sources as possible TeV halos because of different study results for them, but they do not cleanly fit in the properties listed above, indicating their potential complex nature.

One of most important applications of microlensing observations is detecting free-floating planets(FFPs). The time scale of microlensing due to FFPs ($t_{\rm E}$) is short (a few days). Discerning the annual parallax effect in observations from these short-duration events by one observer is barely possible, though their parallax amplitude is larger than that in common events. In microlensing events due to FFPs, the lens-source relative trajectory alters because of the observer's motion by $\boldsymbol{\delta u}$. This deviation is a straight line if $t_{\rm E} \ll P_{\oplus}$, and its size is $\delta u\propto \pi_{\rm{rel}}$ ($P_{\oplus}$ is the observer's orbital period). So, most of observed microlensing events due to close FFPs have simple Paczy\'nsky lightcurves with indiscernible and valuable parallax. To evaluate destructive effects of invisible parallax in such events, we simulate $\sim9650$ microlensing events due to FFPs with $t_{\rm E}<10$ days that are observed only by The Nancy Grace Roman Space Telescope(\wfirst). We conclude that in half of these microlensing events the missing parallax alters the real lightcurves, changing their shape and derived properties(by $\Delta \chi^{2}\gtrsim100$). By fitting Paczy\'nski lightcurves to these affected events we evaluate the relative and dimensionless deviations in the lensing parameters from their real values ($\delta t_{\rm E}, \delta \rho_{\star}, ...$). We conclude that around $46$ FFPs which are discovered by \wfirst\ have lightcurves highly affected by invisible parallax with $\delta t_{\rm E}>0.1~\rm{and}~\delta \rho_{\star}>0.1$. Our study reveals the importance of simultaneous and dense observations of microlensing events viewed by \wfirst\ by other observers rotating the Sun in different orbits.

We report first results from a deep near infrared campaign with the Hubble Space Telescope to obtain late-epoch images of the Hubble Ultra-Deep Field (HUDF), 10-15 years after the first epoch data were obtained. The main objectives are to search for faint active galactic nuclei (AGN) at high redshifts by virtue of their photometric variability, and measure (or constrain) the comoving number density of supermassive black holes (SMBHs), n_SMBH, at early times. In this Letter we present a brief overview of the program and preliminary results regarding eight objects. Three variables are supernovae, two of which are apparently hostless with indeterminable redshifts, although one has previously been recorded at a z\approx 6 galaxy. Two further objects are clear AGN candidates at z=2.0 and 3.2, based on morphology and/or spectroscopy, in particular infrared spectroscopy from JWST. Three variable targets are identified at z=6-7, which are also likely AGN candidates. These sources provide a first measure of n_SMBH in the reionization epoch by photometric variability, which places a firm lower limit of 3x10^{-4} cMpc^{-3}. After accounting for variability and luminosity incompleteness, we estimate n_SMBH \gtrsim 8x10^{-3} cMpc^{-3}, which is the largest value so far reported at these redshifts. This SMBH abundance is also strikingly similar to estimates of n_SMBH in the local Universe. We discuss how these results test various theories for SMBH formation.

We analyse a Chandra observation of the rich globular cluster NGC 362, finding 33 X-ray sources within 1' (1.2 half-mass radii) of the cluster center. Spectral analysis of the brightest source (X1) shows blackbody-like emission, indicating it is likely a quiescent low-mass X-ray binary; we find a possible counterpart that falls in the sub-subgiant region. We use HST UV Globular Cluster Survey (HUGS) photometry to identify 15 potential optical/UV counterparts to these X-ray sources, including two background AGN. We identify no likely CVs, probably due to crowding in optical filters in the core, though we predict of order 8 CVs among the detected X-ray sources. We identify three other sub-subgiants and two red straggler counterparts, which are likely powered by coronal activity, along with five other potential coronally active binary counterparts to three X-ray sources. Finally, we note two unusual counterpart candidates that lie to the red of the red giant branch in V_606 - I_814, and shift well to the blue of the red giant branch in ultraviolet colour-magnitude diagrams. These systems seem to contain a red giant with a distorted evolutionary history, plus a bright blue light source, either a blue straggler star (an Algol-like system) or an accreting white dwarf (a long-period CV, or a symbiotic star).

We present a full general relativistic analytic solution for a radiation-pressure supported equilibrium fluid torus orbiting a rotating neutron star (NS). Previously developed analytical methods are thoroughly applied in the Hartle-Thorne geometry, including the effects of both the NS's angular momentum and quadrupole moment. The structure, size and shape of the torus are explored, focusing especially on the critically thick solution - the cusp tori. For the astrophysically relevant range of NS parameters, we examine how our findings differ from those obtained for the Schwarzschild spacetime. The solutions for rotating stars display signatures of the interplay between relativistic and Newtonian effects where the impact of NS angular momentum and quadrupole moment are almost counterbalanced at the given radius. Nevertheless, the spacetime parameters still strongly influence the size of tori, which can be shown in a coordinate-independent way. Finally, we discuss the importance of the size of the central neutron star, determining whether or not the surrounding torus may exist. We provide a set of tools in a Wolfram Mathematica code, which poses a basis allowing for a further investigation of the impact of the NSs' superdense matter equation of state on the spectral and temporal behaviour of accretion tori.

The four characteristic oscillation frequencies of accretion flows are, in addition to the Keplerian orbital frequency, often discussed in the context of the time variability of the black hole and neutron star (NS) low-mass X-ray binaries (LMXBs). These are namely the frequencies of the axisymmetric radial and vertical epicyclic oscillations, and the frequencies of non-axisymmetric oscillations corresponding to the periastron (radial) and Lense-Thirring (vertical) precessions. In this context, we investigate the effect of the quadrupole moment of a slowly rotating NS and provide complete formulae for calculating these oscillation and precession frequencies, as well as their convenient approximations. Simple formulae corresponding to the geodesic limit of a slender torus (and test particle motion) and the limit of a marginally overflowing torus (torus exhibiting a critical cusp) are presented, and furthermore, more general approximate formulae are included to allow calculations for arbitrarily thick tori. We provide the Wolfram Mathematica code used for our calculations together with C++ and PYTHON codes for calculations of the frequencies. Our formulae can be used for various calculations describing the astrophysical signatures of the NSs' superdense matter equation of state. For instance, we demonstrate that, even for a given fixed number of free parameters, a model accounting for fluid flow precession better matches the frequencies of twin-peak quasiperiodic oscillations observed in NS LMXBs than a model using geodesic precession.

Over the last decade, choked jets have attracted particular attention as potential sources of high-energy cosmic neutrinos. Testing this hypothesis is challenging because of the missing gamma-ray counterpart, hence the identification of other electromagnetic signatures is crucial. A choked-jet source is expected harboring in core-collapse supernovae with extended hydrogen envelopes, leading to the release of ultraviolet and optical emission for a few days. The ultraviolet band will be visible with an unprecedentedly large field of view by the future mission satellite ULTRASAT, for which we investigate the detection prospects in relation to the chocked source visibility in the optical band with the currently operating telescope ZTF. As these sources can produce neutrinos via hadronic and photohadronic interactions in choked jets, we also investigate how neutrino observations by existing Cherenkov high-energy neutrino telescopes (as IceCube and KM3NeT) can be used in association with electromagnetic signals coming from shock breakout events. By considering fiducial parameters of the source population and instruments performances, we estimate the maximum redshift up to which ULTRASAT and ZTF are able to detect ultraviolet and optical signals from these explosions, respectively. Furthermore, we discuss coordinated multi-messenger observations among those instruments and high-energy neutrino telescopes. ULTRASAT will be able to double the volume of sky currently visible by ZTF for the same emitting sources enlarging the sample of observed Type II supernovae by around 60%. For optimized multi-messenger detections, the delay between neutrino produced at the shock breakout occurrence (during the jet propagation inside the stellar envelope) and ULTRASAT observations should be of around 4(5) days, with a subsequent follow-up by instruments like ZTF about one week after.

The surface brightness fluctuation (SBF) method is a robust and efficient way of measuring distances to galaxies containing evolved stellar populations. Although many recent applications of the method have used space-based imaging, SBF remains a powerful technique for ground-based telescopes. Deep, wide-field imaging surveys with subarsecond seeing enable SBF measurements for numerous nearby galaxies. Using a preliminary calibration, Cantiello et al. (2018) presented SBF distances for 89 bright, mainly early-type galaxies observed in the Next Generation Virgo Cluster Survey (NGVS). Here, we present a refined calibration and SBF distances for 278 galaxies extending several magnitudes fainter than in previous work. The derived distances have uncertainties of 5-12\% depending on the properties of the individual galaxies, and our sample is more than three times larger than any previous SBF study of this region. Virgo has a famously complex structure with numerous subclusters, clouds and groups; we associate individual galaxies with the various substructures and map their three-dimensional spatial distribution. Curiously, subcluster A, centered around M87, appears to have two peaks in distance: the main peak at $\sim$16.5 Mpc and a smaller one at $\sim$19.4 Mpc. Subclusters B and C have distances of $\sim$15.8 Mpc. The W and W' groups form a filament-like structure, extending more than 15~Mpc behind the cluster with a commensurate velocity increase of $\sim$1000 \kms\ along its length. These measurements are a valuable resource for future studies of the relationship between galaxy properties and local environment within a dynamic and evolving region.

We present two-dimensional general relativistic radiative magnetohydrodynamical simulations of accretion disks around non-rotating stellar-mass black hole. We study the evolution of an equilibrium accreting torus in different grid resolutions to determine an adequate resolution to produce a stable turbulent disk driven by magneto-rotational instability. We evaluate the quality parameter, $Q_{\theta}$, from the ratio of MRI wavelength to the grid zone size and examine the effect of resolution in various quantitative values such as the accretion rate, magnetisation, fluxes of physical quantities and disk scale-height. We also analyse how the resolution affects the formation of plasmoids produced in the magnetic reconnection events.

We present stellar age determinations for 4,661 red giant branch (RGB) stars in the APO-K2 Catalog, derived using mass estimates from K2 asteroseismology from the K2 Galactic Archaeology Program and elemental abundances from the Apache Point Galactic Evolution Experiment (APOGEE) survey. Our sample includes 17 of the 19 fields observed by K2, making it one of the most comprehensive catalogs of accurate stellar ages across the Galaxy in terms of the wide range of populations spanned by its stars, enabling rigorous tests of Galactic chemical evolution models. Taking into account the selection functions of the K2 sample, the data appear to support the age-chemistry morphology of stellar populations predicted by both inside-out and late-burst scenarios. We also investigate trends in age versus stellar chemistry and Galactic position, which are consistent with previous findings. Comparisons against APOKASC-3 asteroseismic ages show agreement to within ~3%. We also discuss offsets between our ages and spectroscopic ages. Finally, we note that ignoring the effects of $\alpha$-enhancement on stellar opacity (either directly or with the Salaris metallicity correction) results in an ~10% offset in age estimates for the most $\alpha$-enhanced stars, which is an important consideration for continued tests of Galactic models with this and other asteroseismic age samples.

In a strong gravitational lensing system, the distorted light from a source is analysed to infer the properties of the lens. However, light emitted by the lens itself can contaminate the image of the source, introducing systematic errors in the analysis. We present a simple and efficient lens light model based on the well-tested multi-Gaussian expansion (MGE) method for representing galaxy surface brightness profiles, which we combine with a semi-linear inversion scheme for pixelized source modelling. Testing it against realistic mock lensing images, we show that our scheme can fit the lensed images to the noise level, with relative differences between the true input and best-fit lens light model remaining below 5%. We apply the MGE lens light model to 38 lenses from the HST SLACS sample. We find that the new scheme provides a good fit for the majority of the sample with only 3 exceptions -- these show clear asymmetric residuals in the lens light. We examine the radial dependence of the ellipticity and position angles and confirm that it is common for a typical lens galaxy to exhibit twisting, non-elliptical isophotes and boxy / disky isophotes. Our MGE lens light model will be a valuable tool for understanding the hidden complexity of the lens mass distribution.

Updated formation and structure models of Jupiter predict a metal-poor envelope. This is at odds with the two to three times solar metallicity measured by the Galileo probe. Additionally, Juno data imply that water and ammonia are enriched. Here we explore whether Jupiter can have a deep radiative layer separating the atmosphere from the deeper interior. The radiative layer could be caused by a hydrogen-transparency window or depletion of alkali metals. We show that heavy-element accretion during Jupiter's evolution can lead to the desired atmospheric enrichment and that this configuration is stable over billions of years. The origin of the heavy elements could be cumulative small impacts or one large impact. The preferred scenario requires a deep radiative zone due to a local reduction of the opacity at $\sim$ 2000 K by $\sim$ 90%, which is supported by Juno data, and vertical mixing through the boundary with a similar efficiency to molecular diffusion ($D \lesssim 10^{-2}$ cm$^2$/s). Therefore, most of Jupiter's molecular envelope could have solar composition while its uppermost atmosphere is enriched with heavier elements. The enrichment likely originates from the accretion of solid objects. This possibility resolves the long-standing mismatch between Jupiter's interior models and atmospheric composition measurements. Furthermore, our results imply that the measured atmospheric composition of exoplanets does not necessarily reflect their bulk compositions. We also investigate whether the enrichment could be due to the erosion of a dilute core and show that this is highly unlikely. The core-erosion scenario is inconsistent with evolution calculations, the deep radiative layer, and published interior models.

The oscillatory reconnection mechanism is investigated for a parameter study of eight orders of magnitude of resistivity, with a particular interest in the evolution of the oscillating current density at the null point and its associated periodicity. The resistive, nonlinear MHD simulations are solved in 2.5D for different levels of resistivity. Three methods (wavelet analysis, Fourier transform and ANOVA) are used to investigate the effect of resistivity versus resultant period. It is found that there is an independence between the level of background resistivity and the period of the oscillatory reconnection mechanism. Conversely, it is found that resistivity has a significant effect on the maximum amplitude of the current density and the nature of its decay rate, as well as the magnitude of ohmic heating at the null.

We continue our studies of the evolution and cosmological consequences of current-carrying cosmic string networks, described by a charge-velocity-dependent one scale (CVOS) model. We present a detailed calculation of the effects of these networks on the cosmic microwave background (CMB), in the context of this model, and specifically discuss how such current-carrying strings may be distinguished from their uncharged (Nambu-Goto) counterparts by current or forthcoming CMB data. We find that, under the CVOS hypothesis, the constraints on current-carrying strings should not differ much from those of their structureless counterparts in that the impact on the CMB can at most be reduced by a factor of ~25%. Nevertheless, the presence of a current and charge affects the distribution of power among scalar, vector and tensor modes, and also its distribution between small and large scales. It should therefore be possible for future high-sensitivity CMB experiments to distinguish between the two types of strings.

Fuelled by space photometry, asteroseismology is vastly benefitting the study of cool main-sequence stars, which exhibit convection-driven solar-like oscillations. Even so, the tiny oscillation amplitudes in K dwarfs continue to pose a challenge to space-based asteroseismology. A viable alternative is offered by the lower stellar noise over the oscillation timescales in Doppler observations. In this letter we present the definite detection of solar-like oscillations in the bright K5 dwarf $\epsilon$ Indi based on time-intensive observations collected with the ESPRESSO spectrograph at the VLT, thus making it the coolest seismic dwarf ever observed. We measured the frequencies of a total of 19 modes of degree $\ell=0$--2 along with $\nu_{\rm max}=5305\pm176\:{\rm \mu Hz}$ and $\Delta\nu=201.25\pm0.16\:{\rm \mu Hz}$. The peak amplitude of radial modes is $2.6\pm0.5\:{\rm cm\,s^{-1}}$, or a mere ${\sim} 14\%$ of the solar value. Measured mode amplitudes are ${\sim} 2$ times lower than predicted from a nominal $L/M$ scaling relation and favour a scaling closer to $(L/M)^{1.5}$ below ${\sim} 5500\:{\rm K}$, carrying important implications for our understanding of the coupling efficiency between pulsations and near-surface convection in K dwarfs. This detection conclusively shows that precise asteroseismology of cool dwarfs is possible down to at least the mid-K regime using next-generation spectrographs on large-aperture telescopes, effectively opening up a new domain in observational asteroseismology.

We present \texttt{ethraid}, an open source Python package designed to measure the mass ($m_c$) and separation ($a$) of a bound companion from measurements covering a fraction of the orbital period. \texttt{ethraid} constrains $m_c$ and $a$ by jointly modeling radial velocity (RV), astrometric, and/or direct imaging data in a Bayesian framework. Partial orbit data sets, especially those with highly limited phase coverage, are well-represented by a few method-specific summary statistics. By modeling these statistics rather than the original data, \texttt{ethraid} optimizes computational efficiency with minimal reduction in accuracy. \texttt{ethraid} uses importance sampling to efficiently explore the often broad posteriors that arise from partial orbits. The core computations of \texttt{ethraid} are implemented in Cython for speed. We validate \texttt{ethraid}'s performance by using it to constrain the masses and separations of the planetary companions to HD 117207 and TOI-1694. We designed \texttt{ethraid} to be both fast and simple, and to give broad, "quick look" constraints on companion parameters using minimal data. \texttt{ethraid} is pip installable and available on Github.

MAXI J1816-195 is an accreting millisecond X-ray pulsar (AMXP) discovered in 2022. According to the Insight-HXMT data, the pulsations of this source extend all the way to over 100 keV, and its pulse profiles change from a single peak in low-energy range to double peaks in high-energy range. In this work, we simulate its energy spectra and pulse profiles with a Compton scattering Monte Carlo program. The simulation results suggest that the low energy X-ray source on the neutron star surface should be pencil-beamed radiations from the magnetic poles, and there should be a boundary layer in a hollow cylinder shape between the accretion disc and the neutron star surface: the up-scattering of the polar radiations in the boundary layer leads to the double peak structure of the high-energy pulse profile. Under this boundary layer geometry, we suggest that the rarity of AMXPs can be caused by the smearing of the boundary layer. To estimate the mass M and radius R of accretion-powered millisecond pulsars whose surface radiations are badly polluted by the accretion disk and boundary layer, the impact of Compton scattering in the boundary layer on the radiation should be removed before employing the X-ray pulse profile modeling method.

Context. Observing the radio emission from exoplanets is among the most promising methods to detect their magnetic fields and a measurement of an exoplanetary magnetic field will help constrain the planet's interior structure, star-planet interactions, atmospheric escape and dynamics, and habitability. Recently, circularly polarized bursty and slow emission from the $\tau$ Bo\"{o}tis ($\tau$ Boo) exoplanetary system was tentatively detected using LOFAR (LOW-Frequency ARray) beamformed observations. If confirmed, this detection will be a major contribution to exoplanet science. However, follow-up observations are required to confirm this detection. Aims. Here, we present such follow-up observations of the $\tau$ Boo system using LOFAR. These observations cover 70$\%$ of the orbital period of $\tau$ Boo b including the orbital phases of the previous tentative detections. Methods. We used the BOREALIS pipeline to mitigate radio frequency interference and to search for bursty and slowing varying radio signals. BOREALIS was previously used to find the tentative radio signals from $\tau$ Boo. Results. Our new observations do not show any signs of bursty or slow emission from the $\tau$ Bo\"{o}tis exoplanetary system. Conclusions. The cause for our non-detection is currently degenerate. It is possible that the tentative radio signals were an unknown instrumental systematic or that we are observing variability in the planetary radio emission due to changes in its host star. More radio data (preferably multi-site) and ancillary observations (e.g. magnetic maps) are required to further investigate the potential radio emission from the $\tau$ Bo\"{o}tis exoplanetary system.

Aims. We aim to provide an explanation for the PA rotation in GRBs and find the physical conditions that lead to the rotation by 90 degrees in the toroidal magnetic field (MF) model. Moreover, we present some observable polarization properties in the MF model that can be tested in the future. Results. We find that the PA rotation in the toroidal MF is primarily related to three critical factors: the viewing angle, the jet opening angle, and the jet Lorentz factor. Additionally, the PA can experience twice flips of 90 degrees. The conditions for the flips are $q \gtrsim 0.5$ (except for $q\simeq 1$) and $y_j =(\Gamma \theta_j)^2 \gtrsim 4$. However, the two flips in the PA might not be concurrently observable due to the constraint of flux. Taking these conditions into account and assuming a random orientation between the jet axis and the line of sight (LOS), we obtain a theoretical upper limit (without any constraints) for the observed rate of GRBs in the X-ray or $\gamma$-ray band displaying the flips in PA as $R_{ch} \lesssim 80\%$. We further constrain the observed rate as $R_{ch} \sim 16\%$ according to the maximal post-flip polarized flux level, where the observed rate of single and double flips each account for $\sim 8\%$. Moreover, when the LOS is close to the jet edge ($q\to 1$), it is the easiest case to observe the 90-degree PA flip due to the relatively high post-flip polarized flux level.

Potentially habitable planets around nearby stars less massive than solar-type stars could join targets of the spectroscopy of the planetary reflected light with future space telescopes. However, the orbits of most of these planets occur near the diffraction limit for 6-m-diameter telescopes. Thus, while securing contrast-mitigation ability under a broad spectral bandwidth and a finite stellar angular diameter, we must maintain planetary throughput even at the diffraction-limited angles to be able to reduce the effect of the photon noise within a reasonable observation time. A one-dimensional diffraction-limited coronagraph (1DDLC) observes planets near the diffraction limit with undistorted point spread functions but has a finite-stellar diameter problem in wideband use. This study presents a method for wide-spectral-band nulling insensitive to stellar-angular-diameter by adding a fiber nulling with a Lyot-plane phase mask to the 1DDLC. Designing the pattern of the Lyot-plane mask function focuses on the parity of the amplitude spread function of light. Our numerical simulation shows that the planetary throughput (including the fiber-coupling efficiency) can reach about 11% for about 1.35-$\lambda/D$ planetary separation almost independently of the spectral bandwidth. The simulation also shows the raw contrast of about $4\times10^{-8}$ (the spectral bandwidth of 25%) and $5\times10^{-10}$ (the spectral bandwidth of 10%) for $3\times 10^{-2}$ $\lambda/D$ stellar angular diameter. The planetary throughput depends on the planetary azimuthal angle, which may degrade the exploration efficiency compared to an isotropic throughput but is partially offset by the wide spectral band.

In the standard two-component crust-superfluid model of a neutron star, timing noise can arise when the two components are perturbed by stochastic torques. Here it is demonstrated how to analyse fluctuations in radio pulse times of arrival with a Kalman filter to measure physical properties of the two-component model, including the crust-superfluid coupling time-scale and the variances of the crust and superfluid torques. The analysis technique, validated previously on synthetic data, is applied to observations with the Molonglo Observatory Synthesis Telescope of the representative pulsar PSR J1359$-$6038. It is shown that the two-component model is preferred to a one-component model, with log Bayes factor $6.81 \pm 0.02$. The coupling time-scale and the torque variances on the crust and superfluid are measured with $90\%$ confidence to be $10^{7.1^{+0.8}_{-0.5}}$ $\rm{s}$ and $10^{-24.0^{+0.4}_{-5.6}}$ $\rm{rad^2~s^{-3}}$ and $10^{-21.7^{+3.5}_{-0.9}}$ $\rm{rad^2~s^{-3}}$ respectively.

Thermonuclear (type-I) bursts exhibit properties that depend both on the local surface conditions of the neutron stars on which they ignite, as well as the physical parameters of the host binary system. However, constraining the system parameters requires a comprehensive method to compare the observed bursts to simulations. We have further developed the beansp code for this purpose and analysed the bursts observed from IGR J17498-2921, a 401-Hz accretion-powered pulsar, discovered during it's 2011 outburst. We find good agreement with a model having H-deficient fuel with X = 0.15 +/- 0.4, and CNO metallicity about a tenth of the solar value. The model has the system at a distance of 5.7^{+0.6}_{-0.5} kpc, with a massive (approx. 2 M_sun) neutron star and a likely inclination of 60 deg. We also re-analysed the data from the 2002 outburst of the accretion-powered millisecond pulsar SAX J1808.4-3658. For that system we find a substantially closer distance than previously inferred, at 2.7 +/- 0.3 kpc, likely driven by a larger degree of burst emission anisotropy. The other system parameters are largely consistent with the previous analysis. We briefly discuss the implications for the evolution of these two systems.

The morphology of molecular clouds is crucial for understanding their origin and evolution. In this work, we investigate the morphology of the filamentary molecular clouds (filaments for short) using a portion of the $^{12}\text{CO} (J=1-0)$ data from the Milky Way Imaging Scroll Painting (MWISP) project. The data cover an area spanning $104.75^\circ <l< 150.25^\circ , \vert b\vert < 5.25^\circ$ in Galactic coordinates, with $V_\text{LSR}$ ranging from $-95$ to 25 $\text{km s}^{-1}$. Our primary focus is on the orientation and morphological asymmetry of the filaments. To achieve this, we apply several criteria on the data to create a sample of filaments with well-defined straight shape, and we use elliptical fitting to obtain the orientation of each filament, with an estimated error of $\sim1.6^\circ$ for the orientation. We find that the filament orientation with respect to the Galactic plane exhibits a bimodal distribution, a double-Gaussian fitting of which has two centres located at $-38.1^\circ $ and $42.0^\circ $, with 1$\sigma$ of the two Gaussian functions being $35.4^\circ$ and $27.4^\circ$. We do not find significant correlation between the orientation and other parameters, including the Galactic coordinates, radial velocity, velocity width, and physical scale. A considerable fraction of filaments ($\gtrsim 40$ per cent) display head-tail asymmetry, which suggests that mass concentration tends to occur at one end of the filaments.

In this work, we investigate the stellar metallicities of low surface brightness galaxies (LSBGs) and normal high surface brightness galaxies (HSBGs) in the IllustrisTNG100-1 simulation. LSBGs and HSBGs are classified as galaxies with mean central surface brightness $\mu_{\rm r} > 22.0 \ mag \ arcsec^{-2}$ and $\mu_{\rm r} < 22.0 \ mag \ arcsec^{-2}$, respectively. Our findings indicate that both LSBGs and HSBGs exhibit similar number distributions of stellar metallicities at high redshifts ($z>1.5$). However, at low redshifts ($z<1.5$), a clear bimodal distribution of stellar metallicities in galaxies emerges, with LSBGs tending to be more metal-poor than HSBGs. The lower metallicity of LSBGs compared to HSBGs is mostly attributed to the pronounced gradient in the radial distribution of stellar metallicities. The bimodality of stellar metallicity is not attributed to colour distinctions but rather to the slower metal enrichment in LSBGs compared to HSBGs. This suggests that the mechanisms driving metal enrichment in LSBGs differ from those in HSBGs.

Spectropolarimetric results of Fraunhofer lines between 516.3nm and 532.6nm are presented in local upper solar chromosphere, transition zone and inner corona below a height of about 0.04 solar radius above the solar limb. The data were acquired on Nov.3, 2013 during a total solar eclipse in Gabon by the prototype Fiber Arrayed Solar Optical Telescope(FASOT). It is found that the polarization amplitudes of the Fraunhofer lines in these layers depend strongly on specific spectral lines. Fraunhofer line at MgI$b_{1}$518.4nm can have a polarization amplitude up to 0.36$\%$ with respective to the continuum polarization level, while the polarizations of some lines like FeI/CrI524.7nm and FeI525.0nm are often under the detection limit 6.0$\times 10^{-4}$. The polarizations of the Fraunhofer lines, like the emission lines and the continuum, increase with height as a whole trend. The fractional linear polarization amplitudes of inner F-corona can be close to those of inner E-corona, and in general larger than those of inner K-corona. Rotation of the polarization direction of Fraunhofer line is often accompanied with variations in their polarization amplitudes and profile shapes. It is also judged from these polarimetric properties, along with evidences, that neutral atoms exist in these atmospheric layers. Thus the inner F-corona described here is induced by the neutral atoms, and the entropy of the inner corona evaluated becomes larger than those in the underneath layers due to more microstates found.

Sky distributions of large samples of distant active galactic nuclei (AGNs) have shown dipoles significantly larger than the cosmic microwave background (CMB) dipole. However, a recent Bayesian analysis of the QUAIA sample, comprising 1.3 million quasars, has yielded a dipole that seems to be in tandem with the CMB dipole, in contravention of most previous studies of AGN dipoles. Since the question has large cosmological implications, we investigate the QUAIA quasar sample afresh, by directly computing the dipole from asymmetries observed in the source number counts. We instead find a dipole 3-4 times as large as the CMB dipole though in the same direction. Further, it has been claimed elsewhere that the difference between the CMB dipole and the radio dipole estimated from the NRAO VLA Sky Survey (NVSS), the first large catalogue that showed an AGN dipole about four times larger than the CMB dipole, can be fully accounted for by incorporating the shot-noise and clustering contributions to the total NVSS dipole. A careful reinvestigation of the NVSS dipole, however, shows that the random phenomena like shot noise or clustering cannot account for the actually observed NVSS asymmetries, which show a systematic dipole pattern over the sky.

The Simons Array (SA) project is a ground-based Cosmic Microwave Background (CMB) polarization experiment. The SA observes the sky using three telescopes, and POLARBEAR-2A (PB-2A) is the receiver system on the first telescope. For the ground-based experiment, atmospheric fluctuation is the primary noise source that could cause polarization leakage. In the PB-2A receiver system, a continuously rotating half-wave plate (HWP) is used to mitigate the polarization leakage. However, due to the rapid modulation of the polarization signal, the uncertainty in the time constant of the detector results in an uncertainty in the polarization angle. For PB-2A, the time constant of each bolometer needs to be calibrated at the sub-millisecond level to avoid introducing bias to the polarization signal. We have developed a new calibrator system that can be used to calibrate the time constants of the detectors. In this study, we present the design of the calibration system and the preliminary results of the time constant calibration for PB-2A.

We aim to constrain the internal structure and composition of HD 15337 b and c, two short-period planets situated on opposite sides of the radius valley, using new transit photometry and radial velocity data. We acquire 6 new transit visits with the CHaracterising ExOPlanet Satellite (CHEOPS) and 32 new radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS) to improve the accuracy of the mass and radius estimates for both planets. We reanalyse light curves from TESS sectors 3 and 4 and analyse new data from sector 30, correcting for long-term stellar activity. Subsequently, we perform a joint fit of the TESS and CHEOPS light curves, and all available RV data from HARPS and the Planet Finder Spectrograph (PFS). Our model fits the planetary signals, the stellar activity signal and the instrumental decorrelation model for the CHEOPS data simultaneously. The stellar activity was modelled using a Gaussian-process regression on both the RV and activity indicators. We finally employ a Bayesian retrieval code to determine the internal composition and structure of the planets. We derive updated and highly precise parameters for the HD 15337 system. Our improved precision on the planetary parameters makes HD 15337 b one of the most precisely characterised rocky exoplanets, with radius and mass measurements achieving a precision better than 2\% and 7\%, respectively. We are able to improve the precision of the radius measurement of HD 15337 c to 3\%. Our results imply that the composition of HD 15337 b is predominantly rocky, while HD 15337 c exhibits a gas envelope with a mass of at least $0.01\ M_\oplus$.Our results lay the groundwork for future studies, which can further unravel the atmospheric evolution of these exoplanets and give new insights into their composition and formation history and the causes behind the radius gap.

We combine the semi-analytical structure formation model, SASHIMI, which predicts subhalo populations in collisionless, cold dark matter (CDM), with a parametric model that maps CDM halos to self-interacting dark matter (SIDM) halos. The resulting model, SASHIMI-SIDM, generates SIDM subhalo populations down to sub-galactic mass scales, for an arbitrary input cross section, in minutes. We show that SASHIMI-SIDM agrees with SIDM subhalo populations from high-resolution cosmological zoom-in simulations in resolved regimes. Crucially, we predict that the fraction of core-collapsed subhalos peaks at a mass scale determined by the input SIDM cross section and decreases toward higher halo masses, consistent with the predictions of gravothermal models and cosmological simulations. For the first time, we also show that the core-collapsed fraction decreases toward lower halo masses; this result is uniquely enabled by our semi-analytical approach. As a proof of principle, we apply SASHIMI-SIDM to predict the boost to the local dark matter density and annihilation rate from core-collapsed SIDM subhalos, which can be enhanced relative to CDM by an order of magnitude for viable SIDM models. Thus, SASHIMI-SIDM provides an efficient and reliable tool for scanning SIDM parameter space and testing it with astrophysical observations. The code is publicly available at https://github.com/shinichiroando/sashimi-si.

Young & massive stellar clusters (SCs) are a potential source of galactic cosmic rays up to very high energies as a result of two possible acceleration scenarios. Collective stellar winds from massive member stars form a wind-blown bubble with a termination shock (TS) at which particle acceleration to PeV energies may occur. Furthermore, shock acceleration may occur at SNRs expanding inside the bubble. By applying a model of CR acceleration at both the wind TS and SNR shocks to catalogues of known SCs derived from Gaia DR2, we identify the most promising targets to search for evidence of PeVatron activity. Predictions for the secondary fluxes of gamma-ray and neutrino emission are derived based on particle acceleration at the collective wind TS and the subsequent hadronic interactions with the surrounding medium. Predictions from our modelling under baseline and optimistic scenarios are compared to data, finding consistent results. We estimate the detection prospects for future gamma-ray and neutrino experiments. We find that degree-scale angular sizes of the wind-blown bubbles are typical, that may pose a challenge for experimental detection. A shortlist of the most promising candidates is provided, with an anticipated flux range. Of order 10 SCs may be detectable with future facilities, and 1-5 could be currently operating as PeVatrons. Of these, three gamma-ray detected SCs have data within our predicted range. Our model can consistently describe gamma-ray measurements of SC emission. Several further as-yet-undetected SCs offer promising targets for future observations, although the flux range allowed by our model can be large (> factor 10). The large angular size of the wind-blown bubble may lead to low surface brightness emission, worsening the problem of source confusion. Nevertheless, we discuss how further work will help to constrain SCs as PeVatron candidates. (abridged)

We present the discovery of six new triple stellar system candidates composed of an inner eccentric-orbit eclipsing binary with an apsidal motion. These stars were studied using new, precise TESS light curves and a long-term collection of older photometric ground-based data. These data were used for the monitoring of ETVs (eclipse timing variations) and to detect the slow apsidal movements along with additional periodic signals. The systems analysed were ASASSN-V J012214.37+643943.3 (orbital period 2.01156 d, eccentricity 0.15, third body with 3.3 yr period); ASASSN-V J052227.78+345257.6 (2.42673 d, 0.35, 3.2 yr); ASASSN-V J203158.98+410731.4 (2.53109 d, 0.20, 2.7 yr); ASASSN-V J230945.10+605349.3 (2.08957 d, 0.18, 2.3 yr); ASASSN-V J231028.27+590841.8 (2.41767 d, 0.43, 4.9 yr); and NSV 14698 (3.30047 d, 0.147, 0.5 yr). In the system ASASSN-V J230945.10+605349.3, we detected a second eclipsing pair (per 2.99252 d) and found adequate ETV for the pair B, proving its 2+2 bound quadruple nature. All of these detected systems deserve special attention from long-term studies for their three-body dynamics since their outer orbital periods are not too long and because some dynamical effects should be detectable during the next decades. The system NSV 14698 especially seems to be the most interesting from the dynamical point of view due to it having the shortest outer period of the systems we studied, its fast apsidal motion, and its possible orbital changes during the whole 20th century.

The evolution of shocks induced by massive stars does not depend only on the ambient magnetic field strength, but also on its orientation. In the present work, the dynamics of a magnetized blast wave is investigated under the influence of both azimuthal and axial ambient magnetic fields. The blast wave is driven by a central source and forms a shell that results from the accumulation of interstellar matter behind the shock front. A similarity form of the ambient magnetic field and a cylindrical geometry of the blast wave are assumed to obtain self-similar solutions. The model is studied separately for both azimuthal and axial magnetic field and applied to stellar wind bubbles and supernova remnants respectively, using 1D numerical simulations. We found that the magnetized blast wave differs from the self-similar case without an ambient magnetic field. The forward shock front goes slower in the azimuthal case and faster in the axial one. For both tangential orientations, the thickness of the shell increases with the magnetic strength. In the azimuthal case, the thermal energy can be converted to magnetic energy near the inner boundary of the shell. Thus, the temperature drops and the magnetic field increases at the tangential discontinuity of the stellar wind bubble. In the axial case of a supernova remnant, the numerical solution al w ays follows a special curve in the parameter space given by the self-similar model.

We report the discovery of the 10 kilo-parsec (kpc) scale radio lobes in the Sombrero galaxy (NGC 4594), using data from the Continuum Halos in Nearby Galaxies - an Expanded Very Large Array (VLA) Survey (CHANG-ES) project. We further examine the balance between the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas. At the radii $r$ of ~(1-10) kpc, the magnetic pressure inside the lobes and the thermal pressure of the ambient hot gas are generally in balance. This implies that the jets could expand into the surroundings at least to r ~ 10 kpc. The feedback from the active galactic nucleus (AGN) jet responsible for the large-scale lobes may help to explain the unusually high X-ray luminosity of this massive quiescent isolated disk galaxy, although more theoretical work is needed to further examine this possibility.

Recognizing the growing significance of contamination from weak gravitational lensing B-modes induced by Large Scale Structure, we investigate a thorough examination of delensing methods aiming at enhancing the sensitivity of r in primordial B-mode detection experiments. In this study, we focus on two specific delensing approaches. One approach involves computing the gradient-order lensing B-mode template by cross-correlating the E-mode with the lensing potential, and subsequently subtracting it from the observed B-mode signal. Another method entails remapping the observations using the estimated deflection angle. Then demonstrate the delensing efficiency using the simulated maps from future CMB polarization experiments, including two ground-based observations: sub-1 m small aperture telescope and 6 m large aperture telescope, and one future space mission with medium aperture telescope. The results reveal that delensing efficiency will be 40% with ground-based small-aperture only, and increases to 65% when combined with a large-aperture telescope. Furthermore, the future satellite experiment achieves an impressive delensing efficiency of approximately 80%.

This dissertation elaborates on X-ray polarisation features of astrophysical environments near accreting black holes. Although the work was originally assigned to supermassive black holes in active galactic nuclei, the results are also largely applicable to stellar-mass black holes in X-ray binary systems. Several numerical models predicting the X-ray polarisation from these sources are presented, including their immediate applications in the interpretation of the latest discoveries achieved thanks to the Imaging X-ray Polarimetry Explorer (IXPE) mission that began operating in December 2021. The modeling ranges from radiative transfer effects in atmospheres of accretion discs to general-relativistic signatures of X-rays travelling in vacuum near the central black holes to reprocessing events in distant, circumnuclear components. Various scales in physical and computational complexity are examined. A unifying element of this dissertation is the focus on reflection of X-rays from partially ionized matter.

Context: Protoplanetary discs are known to form around nascent stars from their parent molecular cloud as a result of angular momentum conservation. As they progressively evolve and dissipate, they also form planets. While a lot of modeling efforts have been dedicated to their formation, the question of their secular evolution, from the so-called class 0 embedded phase to the class II phase where discs are believed to be isolated, remains poorly understood. Aims: We aim to explore the evolution between the embedded stages and the class II stage. We focus on the magnetic field evolution and the long-term interaction between the disc and the envelope. Methods: We use the GPU-accelerated code \textsc{Idefix} to perform a 3D, barotropic, non-ideal magnetohydrodynamic (MHD) secular core collapse simulation that covers the system evolution from the collapse of the pre-stellar core until 100 kyr after the first hydrostatic core formation and the disc settling while ensuring sufficient vertical and azimuthal resolutions (down to $10^{-2}$ au) to properly resolve the disc internal dynamics and non-axisymmetric perturbations. Results: The disc evolution leads to a power-law gas surface density in Keplerian rotation that extends up to a few 10 au. The magnetic flux trapped in the disc during the initial collapse decreases from 100 mG at disc formation down to 1 mG by the end of the simulation. After the formation of the first hydrostatic core, the system evolves in three phases. A first phase with a small ($\sim 10$ au), unstable, strongly accreting ($\sim10^{-5}$ $\mathrm{M_\odot \, yr^{-1}}$) disc that loses magnetic flux over the first 15 kyr, a second phase where the magnetic flux is advected with a smooth, expanding disc fed by the angular momentum of the infalling material...

We investigate the radial acceleration relation (RAR) in low surface brightness galaxies selected from the Arecibo Legacy Fast ALFA survey. We find that the dynamical acceleration $g_{\rm obs}$ and baryonic gravitational acceleration $g_{\rm bar}$ of the HI-rich low surface brightness galaxies still follow the universal RAR of typical late-type galaxies. The universal RAR signifies a consistent correlation between the distribution of baryonic matter and dark matter across galaxies with diverse morphologies and properties. Our findings suggest that the matter distributions in low surface brightness galaxies may indeed resemble that of general late-type galaxies. This implies that low surface brightness galaxies may not originate from dark matter halos with lower densities; instead, they may originate from the dark matter halos with high spins or form through feedback processes.

How galaxies regulate nuclear growth through gas accretion by supermassive black holes (SMBHs) is one of the most fundamental questions in galaxy evolution. One potential way to regulate nuclear growth is through a galactic wind that removes gas from the nucleus. It is unclear whether galactic winds are powered by jets, mechanical winds, radiation, or via magnetohydrodynamic (MHD) processes. Compact obscured nuclei (CONs) represent a significant phase of galactic nuclear growth. These galaxies hide growing SMBHs or unusual starbursts in their very opaque, extremely compact (r $<$ 100 pc) centres. They are found in approximately 30 % of the luminous and ultra-luminous infrared galaxy (LIRG and ULIRG) population. Here, we present high-resolution ALMA observations ($\sim$30 mas, $\sim$5 pc) of ground-state and vibrationally excited HCN towards ESO 320-G030 (IRAS 11506-3851). ESO 320-G030 is an isolated luminous infrared galaxy known to host a compact obscured nucleus and a kiloparsec-scale molecular wind. Our analysis of these high-resolution observations excludes the possibility of a starburst-driven wind, a mechanically or energy driven active galactic nucleus (AGN) wind, and exposes a molecular MDH wind. These results imply that the nuclear evolution of galaxies and the growth of SMBHs are similar to the growth of hot cores or protostars where gravitational collapse of the nuclear torus drives a MHD wind. These results mean galaxies are capable, in part, of regulating the evolution of their nuclei without feedback.

We present detailed forecasts for the constraints on primordial magnetic fields (PMFs) that will be obtained with the LiteBIRD satellite. The constraints are driven by the effects of PMFs on the CMB anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs and by exploiting all the physical effects, it will be able to improve the current limit coming from Planck. In particular, thanks to its accurate $B$-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving $B_{\rm 1\,Mpc}^{n_{\rm B} =-2.9} < 0.8$ nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, $B_{1\,{\rm Mpc}}^{\rm marg}< 2.2$ nG at 95% C.L. From the thermal history effect, which relies mainly on $E$-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, $\sqrt{\langle B^2\rangle}^{\rm marg}<0.50$ nG at 95% C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in $B$ modes, improving the limits by orders of magnitude with respect to current results, $B_{1\,{\rm Mpc}}^{n_{\rm B} =-2.9} < 3.2$ nG at 95% C.L. Finally, non-Gaussianities of the $B$-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes, providing conservative limits on PMF characteristics that will be achieved with LiteBIRD.

HESS J1813$-$178 is a very-high-energy $\gamma$-ray source spatially coincident with the young and energetic pulsar PSR J1813$-$1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813$-$178 region, taking advantage of improved analysis methods and an extended data set. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the $\gamma$-ray emission in the region with a consistent model, to provide insights into its origin. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 years of Fermi-LAT data and fit a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed $\gamma$-ray emission in the region. In addition to the compact very-high-energy $\gamma$-ray emission centered on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. This study suggests that HESS J1813$-$178 is associated with a $\gamma$-ray PWN powered by PSR J1813$-$1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN.

We report on the serendipitous discovery of 49 HI-rich galaxies in a 2.3 hour Open Time observation with MeerKAT. We present their properties including their HI masses, intensity and velocity maps, and spectra. We determine that at least three HI-rich galaxy groups have been detected, potentially as part of a supergroup. Some members of these galaxy groups show clear interaction with each other in their HI emission. We cross-match the detections with PanSTARRS, WISE and GALEX, and obtain stellar masses and star formation rates. One source is found to be a potential OH megamaser, but further follow-up is required to confidently determine this. For 6 sources with sufficient spatial resolution in HI we produce rotation curves with BBarolo, generate mass models, and derive a dark matter halo mass. While the number of galaxies detected in this relatively short pointing appears to be at the high end of expectations compared to other MeerKAT observations and group HIMF studies, this finding highlights the capability of MeerKAT for other serendipitous discoveries, and the potential for many more HI-rich galaxies to be revealed within both existing and upcoming Open Time datasets.

The ambipolar diffusion approximation is used to model partially ionised plasma dynamics in a single fluid setting. To correctly apply the commonly used version of ambipolar diffusion, a set of criteria should be satisfied including the requirement that the difference in velocity between charges and neutral species (known as drift velocity) is much smaller than the thermal velocity, otherwise the drift velocity will drive a non-negligible level of further collisions between the two species. In this paper we explore the consequence of relaxing this assumption. We show that a new induction equation can be formulated without this assumption. This formulation reduces to the ambipolar induction equation in the case the drift velocity is small. In the large drift velocity limit, the feedback of the drift velocity on the collision frequency results in decreased diffusion of the magnetic field compared with the standard ambipolar diffusion approximation for the same parameters. This has a natural consequence of reducing the frictional heating that can occur. Applying this to results from flux emergence simulations where the expansion of the magnetic field leads to strong adiabatic cooling of the partially ionised chromosphere resulted in a noticeable reduction in the magnitude of the predicted drift velocities.

Neutrino-dominated accretion flows (NDAFs) are one of the important MeV neutrino sources and significantly contribute to the cosmic diffuse neutrino background. In this paper, we investigate the spectrum of diffuse NDAF neutrino background (DNNB) by fully considering the effects of the progenitor properties and initial explosion energies based on core-collapse supernova (CCSN) simulations, and estimate the detectable event rate by Super-Kamiokande detector. We find that the predicted background neutrino flux is mainly determined by the typical CCSN initial explosion energy and progenitor metallicity. For the optimistic cases in which the typical initial explosion energy is low, the diffuse flux of DNNB is comparable to the diffuse supernova neutrino background, which might be detected by the upcoming larger neutrino detectors such as Hyper-Kamiokande, JUNO, and DUNE. Moreover, the strong outflows from NDAFs could dramatically decrease their contribution to the neutrino background.

Polarization of starlight and thermal dust emission caused by aligned dust grains is a valuable tool to characterize magnetic fields (B-fields) and constrain dust properties. However, the physics of grain alignment is not fully understood. To test the popular paradigm of radiative torque (RAT) theory, including RAT alignment (RAT-A) and disruption (RAT-D), we use dust polarization data observed by {\it Planck} and SOFIA/HAWC+ toward two filaments with contrasting physical conditions: Musca, a quiet filament, and OMC-1, a highly dynamic filament due to feedback. We analyze various relations of the observed polarization fraction, $P$, with gas column density, $\NHt$, dust temperature, $\Td$, and polarization angle dispersion function, $\S$. We found that $P$ decreases with increasing $\S$ and increasing $\NHt$, as expected from RAT-A. On the other hand, the $P-\Td$ relation is more complicated; it is a linear correlation at low $\Td$ but turns into an anti-correlation when $\Td$ reaches a certain high value. Next, we compute the polarization fraction on a pixel-by-pixel with B-fields in the plane of the sky using the DustPOL code based on RAT, incorporate the depolarization effect by B-field tangling using $\S$, and compare the realistic polarization model with observations of Musca and OMC-1. For Musca with well-ordered B-fields, our numerical model reproduces the decline of $P$ toward the filament spine (aka. polarization hole), having high $\NHt$ and low $\Td$, indicating the loss of grain alignment efficiency due to RAT-A. For OMC-1, with stronger B-field variations and higher $\Td$, our model can reproduce the observed $P-\Td$ and $P-N(\rm H_{2})$ relations only if the depolarization effect resulting from B-field tangling and RAT-D effect are taken into account. Our results provide more robust observational evidence for the RAT paradigm, particularly the recently discovered RAT-D.

In this work, we investigate the impact of tidal torques and mass transfer on the population of double white dwarfs (DWDs) that will be observed with LISA. Starting from a distribution of DWDs at formation predicted by numerical simulations, we use a semi-analytical model to evolve DWDs under different hypotheses for the efficiency of tidal coupling and the birth spins of white dwarfs. We then estimate the stochastic foreground and the population of resolvable binaries for LISA in each scenario. Our predicted DWD binary distribution can differ substantially from the distribution expected if only gravitational waves (GWs) are considered. If white dwarfs spin slowly, then we predict an excess of systems around a few mHz, due to binaries that outspiral after the onset of mass transfer. This excess of systems leads to differences in the confusion noise, which are most pronounced for strong tidal coupling. In that case, we find a significantly higher number of resolvable binaries than in the GW-only scenario. If instead white dwarfs spin rapidly and tidal coupling is weak, then we find no excess around a few mHz, and the confusion noise due to DWDs is very small. In that scenario, we also predict a subpopulation of outspiralling binaries below 0.1 mHz. Using the Fisher matrix approximation, we estimate the uncertainty on the GW-frequency derivative of resolvable systems. We estimate that, even for non-accreting systems, the mismodelling error due to neglect of effects other than GWs is larger than the statistical uncertainty, and thus this neglect would lead to biased estimates for mass and distance. Our results highlight the need for flexible tools in LISA data analysis. Because our semi-analytical model hinges upon a simplistic approach to determining the stability of mass accretion it will be important to deepen our comprehension of stability in mass-transferring DWD binaries.

Disentangling the radio flux contribution from star formation (SF) and active-galactic-nuclei (AGN) activity is a long-standing problem in extragalactic astronomy, since at frequencies of $\lesssim$ 10 GHz, both processes emit synchrotron radiation. We present in this work the general objectives of the PARADIGM Project, a multi-instrument concept to explore star-formation and mass assembly of galaxies. We introduce two novel general approaches for a detailed multiscale study of the radio emission in local U/LIRGs. In this work, we use archival interferometric data from the Very Large Array (VLA) centred at ~ 6 GHz (C band) and present new observations from the e-Multi-Element Radio-Linked Interferometer Network (e-MERLIN) for UGC5101, VV705, VV250 and UGC8696. Using our image decomposition methods, we robustly disentangle the radio emission into distinct components by combining information from the two interferometric arrays. We use e-MERLIN as a probe of the core-compact radio emission (AGN or starburst) at ~ 20 pc scales, and as a probe of nuclear diffuse emission, at scales ~ 100 - 200 pc. With VLA, we characterise the source morphology and the flux density on scales from 200 pc up to and above 1 kpc. As a result, we find deconvolved and convolved sizes for nuclear regions from ~ 10 pc to ~ 200 pc. At larger scales, we find sizes of 1.5 - 2 kpc for diffuse structures (with effective sizes of ~ 300 - 400 pc). We demonstrate that the radio emission from nuclear extended structures (~ 100 pc) can dominate over core-compact components, providing a significant fraction of the total multiscale SF output. We establish a multiscale radio tracer for star formation by combining information from different instruments. Consequently, this work sets a starting point to potentially correct for overestimations of AGN fractions and underestimates of SF activity.

Multiple explosion mechanisms have been proposed to explain type Ia supernovae (SNe Ia). Through forward modelling, synthetic observables of explosion models can be directly compared to observations of SNe Ia to constrain the explosion physics. Due to the computational expense associated with multi-dimensional explosion and radiative transfer simulations however, empirical modelling tools have also been developed that allow for fast, customised modelling of individual SNe. Such tools have provided useful insights, but the subjective nature with which empirical modelling is performed makes it difficult to obtain robust constraints on the explosion physics or expand studies to large populations of objects. Machine learning accelerated tools have therefore begun to gain traction. In this paper, we present riddler, a framework for automated fitting of SNe Ia spectral sequences up to shortly after maximum light. We train a series of neural networks on realistic ejecta profiles predicted by the W7 and N100 explosion models to emulate full radiative transfer simulations and apply nested sampling to determine the best-fitting model parameters for multiple spectra of a given SN simultaneously. We show that riddler is able to accurately recover the parameters of input spectra and use it to fit observations of two well-studied SNe Ia. We also investigate the impact of different weighting schemes when performing quantitative spectral fitting. As spectroscopic samples of SNe Ia continue to grow, automated spectral fitting tools such as riddler will become increasingly important to maximise the physical constraints that can be gained in a quantitative and consistent manner.

Complex Organic Molecules (COMs) have been found toward low-mass protostars but the origins of the COM emission are still unclear. It can be associated with, for example, hot corinos, outflows, and/or accretion shock/disk atmosphere. We have conducted NOEMA observations toward SVS13A from the PROtostars & DIsks: Global Evolution (PRODIGE) program. Our previous \ce{DCN} observations reveal a possible infalling streamer, which may affect the chemistry of the central protobinary by inducing accretion outbursts and/or shocked gas. Here, we further analyze six O-bearing COMs: CH3OH, aGg'-(CH2OH)2, C2H5OH, CH2(OH)CHO, CH3CHO, and CH3OCHO. Although the COM emission is not spatially resolved, we constrain the source sizes to $\lesssim0.3-0.4$ arcsec (90$-$120 au) by conducting uv-domain Gaussian fitting. Interestingly, the high-spectral resolution data reveal complex line profiles with multiple peaks showing differences between these six O-bearing COMs. The LTE fitting unveils differences in excitation temperatures and emitting areas among these COMs. We further conduct multiple-velocity-component LTE fitting to decompose the line emission into different kinematic components. Up to 6 velocity components are found from the LTE modeling. The temperature, column density, and source size of these components from each COM are obtained. We find a variety in excitation temperatures ($100-500$ K) and source sizes (D$\sim10-70$ au) from these kinematic components from different COMs. The emission of each COM can trace several components and different COMs most likely trace different regions. Given this complex structure, we suggest that the central region is inhomogeneous and unlikely to be heated by only protostellar radiation. We conclude that accretion shocks induced by the large-scale infalling streamer likely exist and contribute to the complexity of the COM emission.

In this work, we perform a statistical study of magnetic field fluctuations in the solar wind at 1 au using permutation entropy and complexity analysis, and the investigation of the temporal variations of the Hurst exponents. Slow and fast wind, magnetic clouds, interplanetary coronal mass ejection (ICME)-driven sheath regions and slow-fast stream interaction regions (SIRs) have been investigated separately. Our key finding is that there are significant differences in permutation entropy and complexity values between the solar wind types at larger timescales and little difference at small timescales. Differences become more distinct with increasing timescale, suggesting that smaller-scale turbulent features are more universal. At larger timescales, the analysis method can be used to identify localized spatial structures. We found that except in magnetic clouds, fluctuation are largely anti-persistent and that the Hurst exponents, in particular in compressive structures (sheaths and SIRs) exhibit a clear locality. Our results shows that, in all cases apart from magnetic clouds at largest scales, solar wind fluctuations are stochastic with the fast wind having the highest entropies and low complexities. Magnetic clouds in turn exhibit the lowest entropy and highest complexity, consistent with them being coherent structures in which the magnetic field components vary in an ordered manner. SIRs, slow wind and ICME sheaths are intermediate to magnetic clouds and fast wind, reflecting the increasingly ordered structure. Our results also indicate that permutation entropy - complexity analysis is a useful tool for characterizing the solar wind and investigating the nature of its fluctuations.

Version 11 of the CHIANTI database and software package is presented. Advanced ionization equilibrium models have been added for low charge states of seven elements (C, N, O, Ne, Mg, Si and S), and represent a significant improvement especially when modelling the solar transition region. The models include the effects of higher electron density and charge transfer on ionization and recombination rates. As an illustration of the difference these models make, a synthetic spectrum is calculated for an electron pressure of 7$\times 10^{15}$ cm$^{-3}$ K and compared with an active region observation from HRTS. Increases are seen of factors of two to five in the predicted radiances of the strongest lines in the UV from Si IV, C IV, and N V, compared to the previous modelling using the coronal approximation. Much better agreement (within 20\%) with the observation is found for the majority of the lines. The new atomic models better equip both those who are studying the transition region and those who are interpreting emission from higher density astrophysical and laboratory plasma. In addition to the advanced models, several ion datasets have been added or updated, and data for the radiative recombination energy loss rate have been updated.

Reports on the detection of carbonates in planetary nebulae (PNe) and protostars suggested the existence of a mechanism that produce these compounds in stellar winds and outflows. A consecutive laboratory study reported a possible mechanism by observing the non-thermodynamic equilibrium (TE), gas-phase condensation of amorphous silicate grains with amorphous calcium carbonate inclusions. It concluded that water vapor was necessary to the formation of the carbonates. We present a laboratory study with pulsed laser ablation of an MgSi target in O$_2$ and CO$_2$ gases and report, in the absence of water vapor, the non-TE, gas-phase condensation of amorphous carbonated magnesium silicate dust. It consists of amorphous silicate grains with formula MgSiO$_3$ that comprise carbonate groups homogeneously dispersed in their structure. The infrared spectra of the grains show the characteristic bands of amorphous silicates and two bands at $\sim$6.3 and $\sim$7.0 $\mu$m that we assign to the carbonate groups. The silicate bands are not significantly affected at an estimated Si:C ratio of 9:1 to 9:2. Such grains could form in winds and outflows of evolved stars and PNe if C atoms are present during silicate condensation. Additionally, we find that Lyman-$\alpha$ radiation dissociates the carbonate groups at the surface of the carbonated silicate grains and we estimate the corresponding photodissociation cross section of (0.04 $\pm$ 0.02) $\times$ 10$^{-16}$ cm$^2$. Therefore, photodissociation would limit the formation of carbonate groups on grains in winds and outflows of stars emitting VUV photons and the carbonates observed in protostars have not formed by gas-phase condensation.

The Tarantula Nebula (30 Doradus) is the most important star-forming complex in the Local Group, offering a microscope on starburst astrophysics. At its heart lies the exceptionally rich young stellar cluster R136, containing the most massive stars known. Stellar winds and supernovae have carved 30 Dor into an amazing display of arcs, pillars, and bubbles. We present first results and advanced data processing products from the 2-Ms Chandra X-ray Visionary Project, "The Tarantula $-$ Revealed by X-rays" (T-ReX). The 3615 point sources in the T-ReX catalog include massive stars, compact objects, binaries, bright pre-main-sequence stars and compact young stellar (sub)clusters in 30 Dor. After removing point sources and excluding the exceptionally bright supernova remnant N157B (30 Dor B), the global diffuse X-ray maps reveal hot plasma structures resolved at 1$-$10 pc scales, with an absorption-corrected total-band (0.5$-$7 keV) X-ray luminosity of $2.110\times 10^{37}$ erg s$^{-1}$. Spatially-resolved spectral modeling provides evidence for emission lines enhanced by charge-exchange processes at the interfaces. We identify a candidate for the oldest X-ray pulsar detected to date in 30 Dor, PSR J0538-6902, inside a newly-resolved arctuate X-ray wind nebula, the Manta Ray. The long time baseline of T-ReX monitored dozens of massive stars, several showing periodic variability tied to binary orbital periods, and captured strong flares from at least three low-mass Galactic foreground stars.

We present results regarding the longitudinal migrations of cool stellar spots that exhibit remarkable oscillations and explore their possible causes. We conducted analyses using high-quality data from nine target systems of various spectral types, spanning from F to M, which were observed by the Kepler Satellite. The systems in which the behaviour of the spots was examined are as follows: KIC 4357272, KIC 6025466, KIC 6058875, KIC 6962018, KIC 7798259, KIC 9210828, KIC 11706658, KIC 12599700, and KIC 8669092. Basic stellar parameters were calculated from light curve analysis using the PHOEBE V.0.32 software, and light curves were modelled to obtain sinusoidal variations occurring out-of-eclipses phases, induced by rotational modulation. Subsequently, we calculated the minimum times of the obtained sinusoidal variations using the Fourier transform. The distributions of {\theta}min corresponding to these minimum times over time were computed using linear fits to determine the longitudinal migrations of the spotted areas. We then compared the longitudinal migration periods with the stellar parameters found in the literature. In addition, we also found a secondary variation in the spot migrations apart from the linear models. Our results revealed that the longitudinal migration periods vary in relation to the B - V colour index of the stars.

We study the capacity of Bayesian Neural Networks (BNNs) to detect new physics in the dark matter power spectrum. As in previous studies, the Bayesian Cosmological Network (BaCoN) classifies spectra into one of 5 classes: $\Lambda$CDM, $f(R)$, $w$CDM, Dvali-Gabadaze-Porrati (DGP) gravity and a 'random' class, with this work extending it to include the effects of massive neutrinos and baryonic feedback. We further develop the treatment of theoretical errors in BaCoN-II, investigating several approaches and identifying the one that best allows the trained network to generalise to other power spectrum modelling prescriptions. In particular, we compare power spectra data produced by EuclidEmulator2, HMcode and halofit, all supplemented with the halo model reaction to model beyond-$\Lambda$CDM physics. We investigate BNN-classifiers trained on these sets of spectra, adding in Stage-IV survey noise and various theoretical error models. Using our optimal theoretical error model, our fiducial classifier achieves a total classification accuracy of $\sim$ 95% when it is trained on EuclidEmulator2-based spectra with modification parameters drawn from a Gaussian distribution centred around $\Lambda$CDM ($f(R)$: $\sigma_{fR0} = 10^{-5.5}$, DGP: $\sigma_{r\mathrm{c}} = 0.173$, $w$CDM: $\sigma_{w0} = 0.097$, $\sigma_{wa}=0.32$). This strengthens the promise of this method to glean the maximal amount of unbiased gravitational and cosmological information from forthcoming Stage-IV galaxy surveys.

At redshifts beyond $z \gtrsim 30$, the 21cm line from neutral hydrogen is expected to be essentially the only viable probe of the 3D matter distribution. The lunar far-side is an extremely appealing site for future radio arrays that target this signal, as it is protected from terrestrial radio frequency interference, and has no ionosphere to attenuate and absorb radio emission at low frequencies (tens of MHz and below). We forecast the sensitivity of low-frequency lunar radio arrays to the bispectrum of the 21cm brightness temperature field, which can in turn be used to probe primordial non-Gaussianity generated by particular early universe models. We account for the loss of particular regions of Fourier space due to instrumental limitations and systematic effects, and predict the sensitivity of different representative array designs to local-type non-Gaussianity in the bispectrum, parametrised by $f_{\rm NL}$. Under the most optimistic assumption of sample variance-limited observations, we find that $\sigma(f_{\rm NL}) \lesssim 0.01$ could be achieved for several broad redshift bins at $z \gtrsim 30$ if foregrounds can be removed effectively. These values degrade to between $\sigma(f_{\rm NL}) \sim 0.03$ and $0.7$ for $z=30$ to $z=170$ respectively when a large foreground wedge region is excluded.

Over the last few years, primordial black holes (PBHs) have emerged as a strong candidate for cold dark matter. A significant number of PBHs are produced when the strength of the primordial scalar power spectrum is enhanced on small scales (compared to the COBE normalized values on large scales). Such primordial spectra also inevitably lead to strong amplification of the scalar-induced, secondary gravitational waves (GWs) at higher frequencies. The recent detection of the stochastic gravitational wave background (SGWB) by the pulsar timing arrays (PTAs) has opened up the possibility of directly probing the very early universe. Different studies have shown that, when PBHs are assumed to have been formed during the epoch of radiation domination, the mechanism for the amplification of the scalar-induced GWs that is required to explain the PTA data can overproduce the PBHs over some ranges of masses. In this work, we assume a specific functional form for the primordial scalar power spectrum and examine the production of PBHs and the scalar-induced secondary GWs during the phase of reheating, which precedes the standard epoch of radiation domination. Specifically, we account for the uncertainties in the conditions for the formation of PBHs and ensure that the extent of PBHs produced remains within the observational bounds. We find that the scalar-induced SGWB generated during a phase of reheating with a steeper equation of state (than that of radiation) fit the NANOGrav 15-year data with a stronger Bayesian evidence than the astrophysical scenario involving GWs produced by merging supermassive binary black holes.

The X-ray Integral Field Unit (X-IFU) instrument on the future ESA mission Athena X-ray Observatory is a cryogenic micro-calorimeter array of Transition Edge Sensor (TES) detectors designed to provide spatially-resolved high-resolution spectroscopy. The onboard reconstruction software provides energy, spatial location and arrival time of incoming X-ray photons hitting the detector. A new processing algorithm based on a truncation of the classical optimal filter and called 0-padding, has been recently proposed aiming to reduce the computational cost without compromising energy resolution. Initial tests with simple synthetic data displayed promising results. This study explores the slightly better performance of the 0-padding filter and assess its final application to real data. The goal is to examine the larger sensitivity to instrumental conditions that was previously observed during the analysis of the simulations. This 0-padding technique is thoroughly tested using more realistic simulations and real data acquired from NASA and NIST laboratories employing X-IFU-like TES detectors. Different fitting methods are applied to the data, and a comparative analysis is performed to assess the energy resolution values obtained from these fittings. The 0-padding filter achieves energy resolutions as good as those obtained with standard filters, even with those of larger lengths, across different line complexes and instrumental conditions. This method proves to be useful for energy reconstruction of X-ray photons detected by the TES detectors provided proper corrections for baseline drift and jitter effects are applied. The finding is highly promising especially for onboard processing, offering efficiency in computational resources and facilitating the analysis of sources with higher count rates at high resolution.

The Massive and Distant Clusters of WISE Survey 2 (MaDCoWS2) is a new survey designed as the successor of the original MaDCoWS survey. MaDCoWS2 improves upon its predecessor by using deeper optical and infrared data and a more powerful detection algorithm (PZWav). As input to the search, we use grz photometry from DECaLS in combination with W1 and W2 photometry from the CatWISE2020 catalog to derive the photometric redshifts with full redshift probability distribution functions for WISE-selected galaxies. Cluster candidates are then detected using the PZWav algorithm to find three-dimensional galaxy overdensities from the sky positions and photometric redshifts. This paper provides the first MaDCoWS2 data release, covering 1461 (1838 without masking) deg^2 centered on the Hyper-SuprimeCam Subaru Strategic Program equatorial fields. Within this region, we derive a catalog of 22,970 galaxy cluster candidates detected at S/N>5. These clusters span the redshift range 0.1<z<2, including 1312 candidates at z>1.5. We compare MaDCoWS2 to six existing catalogs in the area. We rediscover 60%-92% of the clusters in these surveys at S/N>5. The medians of the absolute redshift offset are <0.02 relative to these surveys, while the standard deviations are less than 0.06. The median offsets between the detection position from MaDCoWS2 and other surveys are less than 0.25 Mpc. We quantify the relation between S/N and gas mass, total mass, luminosity, and richness from other surveys using a redshift-dependent power law relation. We find that the S/N-richness relation exhibits the lowest scatter.

Supermagnified stars are gravitationally lensed individual stars that are located close to a caustic of a lensing galaxy cluster, and have their flux magnified by a large enough factor (typically ~ 1000) to make them detectable with present telescopes. The maximum magnification is limited by microlensing caused by intracluster stars or other compact objects, which create a network of corrugated critical lines with an angular width proportional to the surface density of microlenses. We consider a set of 9 cases of supermagnified stars reported in the literature, and derive an upper limit on the surface density of compact objects, such as primordial black holes, that might be present as a fraction of the dark matter in addition to known intracluster stars. Any such additional compact objects would widen the corrugated critical line network and therefore the width of the distribution of supermagnified stars around the modeled critical lines of the lens. We find that any compact objects, including primordial black holes, with masses above $\sim 10^{-6}\, M_{\odot}$ (for which the microcaustics are smaller than the typical angular size of supermagnified stars) cannot account for more than ~ 3% of the dark matter.

The article presents a theoretical study of Oleinik resonances in the process of scattering a gamma quantum by an ultrarelativistic electron in the field of a strong electromagnetic wave. It is shown that under resonant conditions, the scattering channels of the reaction effectively split into two first-order processes according to a fine structure constant such as the external field-stimulated Compton effect. And the annihilation channel of the reaction effectively decays into direct and reverse the external field-stimulated Breit-Wheeler processes. The significant dependence of the resonant energy of final particles and resonant cross sections on the outgoing angles of the final gamma quantum, the number of absorbed and emitted photons of the wave, as well as the characteristic quantum parameters of the problem is shown. These quantum parameters are determined by the ratio of the initial particle energies to the characteristic energies of the Compton effect and the Breit-Wheeler process. An unambiguous relationship between the outgoing angles of final electrons and gamma quanta has been obtained, which qualitatively distinguishes the resonant process from the non-resonant one. The cases when the energy of the initial electrons significantly exceeds the energy of the initial gamma quanta have been studied. The conditions under which the energy of high-energy initial electrons is converted into the energy of final gamma quanta are obtained. At the same time, the resonant differential cross-section of such a process significantly (by several orders of magnitude) exceeds the corresponding non-resonant cross-section. This theoretical study predicts a number of new physical effects that may explain the high-energy fluxes of gamma quanta born near neutron stars and magnetars.

We demonstrate that gravitational particle production (GPP) of a massive, Abelian, vector (Proca) field during inflation in the presence of nonminimal coupling to gravity may suffer from an instability which leads to runaway production of high-momentum modes. This is untenable unless there is some mechanism to regulate the runaway. We discuss the parameter space of the particle mass and nonminimal couplings where such a runaway occurs and possible ways to tame the runaway. We find that there is no obvious way to resolve the runaway in a UV completion or with kinetic mixing to the standard model.

The invisible decay of cold dark matter into a slightly lighter dark sector particle on cosmological time-scales has been proposed as a solution to the $S_8$ tension. In this work we discuss the possible embedding of this scenario within a particle physics framework, and we investigate its phenomenology. We identify a minimal dark matter decay setup that addresses the $S_8$ tension, while avoiding the stringent constraints from indirect dark matter searches. In our scenario, the dark sector contains two singlet fermions $N_{1,2}$, quasi-degenerate in mass, and carrying lepton number so that the heaviest state ($N_2$) decays into the lightest ($N_1$) and two neutrinos via a higher-dimensional operator $N_2\to \bar N_1\nu\nu$. The conservation of lepton number, and the small phase-space available for the decay, forbids the decay channels into hadrons and strongly suppresses the decays into photons or charged leptons. We derive complementary constraints on the model parameters from neutrino detectors, freeze-in dark matter production via $\nu\nu\to N_1N_2$, collider experiments and blazar observations, and we show that the upcoming JUNO neutrino observatory could detect signals of dark matter decay for model parameters addressing the $S_8$ tension if the dark matter mass is below $\simeq 1$ GeV.

Given the growing interest in gravitational-wave and cosmological parity-violating effects in dynamical Chern-Simons (dCS) gravity, it is crucial to investigate whether the scalar-gravitational Pontryagin term in dCS persists when formulated in the context of the $\text{U(1)}_{\text{B}-\text{L}}$ anomaly in the Standard Model (SM). In particular, it has been argued that dCS gravity can be reduced to Einstein gravity after ''rotating away'' the gravitational-Pontryagin coupling into the phase of the Weinberg operator $\unicode{x2013}$ analogous to the rotation of the axion zero-mode into the quark mass matrix. We find that dCS is nontrivial if the scalar field $\phi$ has significant space-time dependence from dynamics. We provide a comprehensive consideration of the dCS classical and quantum symmetries relevant for embedding a dCS sector in the SM. We find that, because of the B-L chiral gravitational anomaly, the scalar-Pontryagin term cannot be absorbed by a field redefinition. Assuming a minimal extension of the SM, we also find that a coupling of the dCS scalar with right-handed neutrinos induces both the scalar-Pontryagin coupling and an axion-like phase in the dimension-five Weinberg operator. We comment on the issue of gauging the $\text{U(1)}_{\text{B}-\text{L}}$, the observational effects with these two operators present for upcoming experiments, and the origin of dCS gravity in string theory.

In this work, we investigate the bouncing behavior of the universe within the framework of $f(R,L_m)$ gravity, using a simple form of $f(R,L_m)=\frac{R}{2}+L_m^\gamma$ (where $\gamma$ is a free model parameter) as previously studied. The model predicts a vanishing Hubble parameter in the early and late times, with the deceleration parameter approaching a specific limit at the bouncing point. The EoS parameter is observed to cross the phantom divide line ($\omega=-1$) near the bouncing point, indicating a significant transition from a contracting to an expanding phase. The model satisfies the necessary energy conditions for a successful bouncing scenario, with violations indicating exotic matter near the bouncing point. Stability conditions are satisfied for certain values of $\gamma$ near the bouncing point, but potential instabilities in late-time evolution require further investigation. Finally, we conclude that the $f(R,L_m)$ gravity model is promising for understanding the universe's dynamics, especially during events like the bouncing phase.

We revisit the properties of total time-derivative terms as well as terms proportional to the free equation of motion (EOM) in a Schwinger-Keldysh formalism. They are relevant to the correct calculation of correlation functions of curvature perturbations in the context of inflationary Universe. We show that these two contributions to the action play different roles in the operator or the path-integral formalism, but they give the same correlation functions as each other. As a concrete example, we confirm that the Maldacena's consistency relations for the three-point correlation function in the slow-roll inflationary scenario driven by a minimally coupled canonical scalar field hold in both the operator and path-integral formalisms. We also give some comments on loop calculations.

Nonstandard interaction is expected to be a crucial hint to explain the experimental data of neutrino scattering off electrons. In this context, the nonstandard interaction vector and axial-vector couplings are needed to be extracted from recent experiments and a few of them are now available in the literature. With these coupling bounds, in this paper, I explore their impacts on the neutrinos interacting with the free electron gas in dense matter. To this end, I compute and predict the neutrino differential cross section and mean free path in dense matter for all those experimental bounds. Interesting behavior in the neutrino cross sections and mean free path is found for the different nonstandard interaction couplings from different experiment constraints. I also found that the neutrino cross-section and mean free path in the dense matter are very sensitive to values and signs of the nonstandard interaction couplings, leading to different prediction results to the Standard Model cross-section and mean free path.

The historical detection of gravitational waves from the binary neutron star merger GW170817 is providing fundamental new insights into the astrophysical site for the creation of the heaviest elements in the cosmos and on the equation of state of neutron-rich matter. Shortly after this historical detection, electromagnetic observations of neutron stars together with measurements of the properties of neutron-rich nuclei at terrestrial facilities have placed additional constraints on the dynamics of neutron-rich matter. It is this unique synergy between heaven and earth that is the focus of this article.

We study the structure of static spherical stars composed of non-relativistic matter in linear massive gravity with or without the Fierz-Pauli (FP) tuning. Adopting a polytropic equation of state, we construct master differential equations for the stellar profile function, which is fourth order in the FP theory or sixth order in generic non-FP theories, where the difference in the differential order reflects the presence of a ghost spin-0 graviton in the latter. In both cases, even when the spin-0 ghost is present, we find exact solutions with finite radius for the polytropic indices n = 0 and 1. Analyzing the dependences of the stellar radius, mass, and Yukawa charge on the graviton masses, we observe that a discontinuous behavior arises in the massless limit of the FP theory similarly to the van Dam-Veltman-Zakharov discontinuity, while it is absent in non-FP theories. We discuss rough observational constraints on the graviton masses.

The interaction of a gravitational wave (GW) with an elastic body is usually described in terms of a GW "force" driving the oscillations of the body's normal modes. However, this description is only possible for GW frequencies for which the response of the elastic body is dominated by a few normal modes. At higher frequencies the normal modes blend into a quasi-continuum and a field-theoretical description, as pioneered by Dyson already in 1969, becomes necessary. However, since the metric perturbation $h_{\mu\nu}$ is an intrinsically relativistic object, a consistent coupling to GWs can only be obtained within a relativistic (and, in fact generally covariant) theory of elasticity. We develop such a formalism using the methods of modern effective field theories, and we use it to provide a derivation of the interaction of elastic bodies with GWs valid also in the high-frequency regime, providing a first-principle derivation of Dyson's result (and partially correcting it). We also stress that the field-theoretical results are obtained working in the TT frame, while the description in terms of a force driving the normal modes is only valid in the proper detector frame. We show how to transform the results between the two frames. Beside an intrinsic conceptual interest, these results are relevant to the computation of the sensitivity of the recently proposed Lunar Gravitational Wave Antenna.

In this work, we explore new constraints on phantom scalar field cosmologies with a scalar field employing early times catalogues related to CMB measurements, along with the local standard observables, like Supernovae Type Ia (SNIa), $H(z)$ measurements (Cosmic Clocks), and Baryon Acoustic Oscillations (BAO) baselines. In particular, we studied a tracker phantom field with hyperbolic polar coordinates that have been proposed in the literature. The main goal is to obtain precise cosmological constraints for $H_0$ and $\sigma_8$, in comparison to other constructions that present tension in early cosmological parameters. Our results show that phantom scalar field cosmologies have a reduced statistical tension on $H_0$ that it is less than 3$\sigma$ using model-independent CMB catalogues as SPT-3G+WMAP9 and ACTPol DR-4+WMAP9 baselines. This suggests these models using a different phantom potential might address the Hubble constant problem and reduce the systematics involved.

We present the details for the covariant renormalization of the stress tensor for vacuum tensor perturbations at the level of the effective action, adopting Hadamard regularization techniques to isolate short distance divergences and gauge fixing via the Faddeev-Popov procedure. The subsequently derived renormalized stress tensor can be related to more familiar forms reliant upon an averaging prescription, such as the Isaacson or Misner-Thorne-Wheeler forms. The latter, however, are premised on a prior scale separation (beyond which the averaging is invoked) and therefore unsuited for the purposes of renormalization. This can lead to potentially unphysical conclusions when taken as a starting point for the computation of any observable that needs regularization, such as the energy density associated to a stochastic background. Any averaging prescription, if needed, should only be invoked at the end of the renormalization procedure. The latter necessarily involves the imposition of renormalization conditions via a physical measurement at some fixed scale, which we retrace for primordial gravitational waves sourced from vacuum fluctuations through direct or indirect observation.

General relativity predicts that two counter-orbiting clocks around a spinning mass differ in the time required to complete the same orbit. The difference in these two values for the orbital period is generally referred to as the gravito-magnetic (GM) clock effect. It has been proposed to measure the GM clock effect using atomic clocks carried by satellites in prograde and retrograde orbits around the Earth. The precision and stability required for satellites to accurately perform this measurement remains a challenge for current instrumentation. One of the most accurate clocks in the Universe is a millisecond pulsar, which emits periodic radio pulses with high stability. Timing of the pulsed signals from millisecond pulsars has proven to be very successful in testing predictions of general relativity and the GM clock effect is potentially measurable in binary systems. In this work we derive the generic GM clock effect by considering a slowly-spinning binary system on an elliptical orbit, with both arbitrary mass ratio and arbitrary spin orientations. The spin-orbit interaction introduces a perturbation to the orbit, causing the orbital plane to precess and nutate. We identify several different contributions to the clock effects: the choice of spin supplementary condition and the observer-dependent definition of a full revolution and "nearly-identical" orbits. We discuss the impact of these subtle definitions on the formula for GM clock effects and show that most of the existing formulae in the literature can be recovered under appropriate assumptions.

Chiral magnetohydrodynamics is devoted to understanding the late-time and long-distance behavior of a system with an Adler-Bell-Jackiw anomaly at finite temperatures. The non-conservation of the axial charge is determined by the topological density $\vec{E} \cdot \vec{B}$; in a classical hydrodynamic description this decay rate can be suppressed by tuning the background magnetic field to zero. However it is in principle possible for thermal fluctuations of $\vec{E} \cdot \vec{B}$ to result in a non-conservation of the charge even at vanishing $B$-field; this would invalidate the classical hydrodynamic effective theory. We investigate this by computing the real-time susceptibility of the topological density at one-loop level in magnetohydrodynamic fluctuations, relating its low-frequency limit to the decay rate of the axial charge. We find that the frequency-dependence of this susceptibility is sufficiently soft as to leave the axial decay rate unaffected, validating the classical hydrodynamic description. We show that the susceptibility contains non-analytic frequency-dependence which is universally determined by hydrodynamic data. We comment briefly on possible connections to the recent formulation of the ABJ anomaly in terms of non-invertible symmetry.