Papers for Friday, Feb 14 2025

Rare Poisson processes (PP) during cosmic inflation can lead to signatures that are localized in position space and are not well captured by the standard two- or higher-point correlation functions of primordial density perturbations. As an example, PP can lead to localized overdense regions that are far denser than the ones produced through standard inflationary fluctuations. As a result, such overdense regions collapse earlier than expected based on the standard $\Lambda$CDM model and would host anomalously high-redshift galaxies. We describe some general aspects of such PP and consider a particular realization in the context of inflationary particle production. We then show that the masses and redshifts of the resulting galaxies can lie in a range discoverable by the James Webb Space Telescope (JWST) and future surveys, while being consistent with existing constraints on the matter power spectrum and UV luminosity functions at lower redshifts.

We show that the superhorizon-limit curvature perturbations are conserved at one-loop level in single-field inflation models with a transient non-slow-roll period. We take the spatially-flat gauge, where the backreaction plays a crucial role for the conservation of superhorizon curvature perturbations unless the counter terms are tuned. We calculate the backreaction with the in-in formalism. In addition, we explicitly show the renormalization of the UV divergences with the counter terms.

We study the influence of axion dark-matter cores on the orbits of stars at the Galactic centre. This dark matter candidate condenses into dense, solitonic cores, and, if a super-massive black hole is present at the centre of such a core, its central part forms a 'gravitational atom'. Here, we calculate the atom's contribution to the gravitational potential felt by a Galactic-centre star, for a generic quantum state of the atom. We study the angular-momentum dynamics this potential induces, and show that it is similar to vector resonant relaxation. Its influence is found to be sufficiently strong that such a dynamical component should be accounted for in Galactic-centre modelling. For the Milky Way, the atom is expected to have some spherical asymmetry, and we use this to derive a stability condition for the disc of young, massive stars at the Galactic centre - if the atom's mass is too large, then the disc would be destroyed. Thus, the existence of this disc constrains the mass of the axion particles comprising the solitonic core; for plausible parameter values, such a core is found to be in tension with the existence of the clockwise stellar disc at $2\sigma$ for $4.4\times 10^{-20}\,\textrm{eV} \leq m_a \leq 5.3\times 10^{-20}\,\textrm{eV}$. These constraints will tighten significantly with future, improved data.

For synthesising star clusters and whole galaxies, stellar populations need to be modelled by a set of four functions that define their initial distribution of stellar masses and of the orbital properties of their binary-star populations. The initial binaries are dynamically processed in different embedded clusters explaining differences in the observed populations. The approach summarised here, for which the Aarseth Nbody codes have been instrumental, allows inference of the initial conditions of the globular cluster omega Cen and the quantification of the stellar merger rate as a function of stellar spectral type, of the role of multiples and mergers for the Cepheid population, and predictions of extragalactic observables. The observability of the four initial distribution functions and their physical and philosophical meaning are also briefly raised. Evidence for the variation of these functions on the physical conditions of star formation and future steps towards extensions to include higher-order multiple systems are touched upon.

We present an analysis of deep $\textit{JWST}$/NIRSpec spectra of star-forming galaxies at $z\simeq1.4-10$, observed as part of the AURORA survey. We infer median low-ionization electron densities of $268_{-49}^{+45}~\rm cm^{-3}$, $350_{-76}^{+140}~\rm cm^{-3}$, and $480_{-310}^{+390}~\rm cm^{-3}$ at redshifts z$=2.3$, $z=3.2$, and $z=5.3$, respectively, revealing an evolutionary trend following $(1+z)^{1.5\pm0.6}$. We identify weak positive correlations between electron density and star formation rate (SFR) as well as SFR surface density, but no significant trends with stellar mass or specific SFR. Correlations with rest-optical emission line ratios show densities increasing with $\rm [NeIII]\lambda3869/[OII]\lambda3727$ and, potentially, $\rm [OIII]\lambda5007/[OII]\lambda3727$, although variations in dust attenuation complicate the latter. Additionally, electron density is more strongly correlated with distance from the local BPT sequence than can be explained by simple photoionization models. We further derive electron densities from the CIII] doublet probing higher-ionization gas, and find a median value of $1.4_{-0.5}^{+0.7}\times10^4~\rm cm^{-3}$, $\sim30$ times higher than densities inferred from [SII]. This comparison suggests a consistent HII region structure across cosmic time with dense, high-ionization interiors surrounded by less dense, low-ionization gas. We compare measurements of AURORA galaxies to predictions from the SPHINX galaxy formations, highlighting the interplay between residual molecular cloud pressure in young galaxies and feedback from stellar winds and supernovae as galaxies mature.

In galaxies, the flattening of the spectrum at low radio frequencies below 300 MHz has been the subject of some debate. A turnover at low frequencies could be caused by multiple physical processes, which can yield new insights into the properties of the ionised gas in the interstellar medium. We investigate the existence and nature of the low-frequency turnover in the HII regions of M 101. We study the nearby galaxy M 101 using the LOw Frequency ARray (LOFAR) at frequencies of 54 and 144 MHz, Apertif at 1370 MHz, and published combined map from the Very Large Array (VLA) and Effelesberg telescope at 4850 MHz. The spectral index between 54 and 144 MHz is inverted at the centres of HII regions. We find a significant low-frequency flattening at the centres of five out of six HII regions that we selected for this study. The low frequency flattening in HII regions of M 101 can be explained with two different free-free absorption models. The flattening is localised in a region smaller than 1.5 kpc and can only be detected with high resolution (better than 45''). The detection of low frequency flattening has important consequences for using radio continuum observations below 100 MHz to measure extinction-free star-formation rates.

In this study, the distances of stellar systems classified as cataclysmic variables in the literature were determined by using the distance compiled from Bailer-Jones et al. (2021). The spatial distributions of cataclysmic variables in the heliocentric Galactic coordinate system are obtained and their positions in the Hertzsprung-Russell (HR) diagram constructed from Gaia colors are discussed.

The main fuelling processes for Active Galactic Nuclei (AGN) are currently unknown. Previous work showed that galaxies with a large kinematic misalignment between their stellar and gas reservoirs have a higher AGN fraction than galaxies without misalignment. Such misalignment is a strong indication of a past galaxy interaction or an external accretion event. In this work we use integral field spectroscopy data from the SAMI and MaNGA surveys to investigate the AGN luminosity as a function of kinematic misalignment angle. Our sample of AGN exhibit bolometric luminosities in the range 10^40 to 10^43 erg/s, indicative of low to moderate luminosity AGN. We find no correlation between AGN luminosity as a function of misalignment for AGN host galaxies from both surveys. We find some differences between the AGN luminosity of early- and late-type AGN host galaxies (ETGs, LTGs). AGN in LTG hosts have a wider luminosity range, with most LTG hosts showing aligned stellar to gas kinematics. AGN in ETG hosts have a luminosity range that does not depend on misalignment angle, suggesting AGN in ETG hosts are consistent with being fuelled by external accretion events, irrespective of their stellar to gas kinematic misalignment. While all the AGN in ETGs in our sample are consistent with being activated and fuelled by external gas, the range of observed AGN luminosities is likely caused by secondary factors such as the amount of fresh gas brought into the galaxy by the external interaction.

It has long been known that, in the absence of a dark matter (DM) halo, galaxy discs tend to develop global gravitational instabilities that strongly modify their initial structure. The recent discovery of gas-rich ultra diffuse galaxies (UDGs) that seem to live in DM halos with very low concentrations, a very atypical configuration in the standard cosmological framework, poses therefore a crucial question: is the small contribution from such DM halos sufficient to stabilize the UDG discs? In this work we investigate this question, focusing on the extreme UDG AGC 114905, which previous works found to be unstable. Here, we revisit these studies, using idealised numerical simulations with AREPO of a system composed by a stellar disc, a gas disc and a DM halo in initial equilibrium with each other and with properties based on slightly revised observational data of AGC 114905. We explore different scenarios for the DM halo and we run our simulations for 5 Gyr. We find that in all cases the stellar and the gas discs are stable and that their initial density distributions and kinematic properties remain unchanged during the course of the simulation. We discuss how the apparent discrepancy with previous works (where the UDG developed instabilities) is due to our discs being dynamically hotter and living in slightly more massive DM halos, in accordance with the new observational constraints, previously unavailable. Our findings demonstrate that AGC 114905 (and likely other similar UDGs) can evolve unperturbed in halos that challenge current cosmological models.

We analyse the 2021 outburst from the black hole X-ray binary GX339-4 observed by NICER around the hard to soft transition, when the system exhibits flip-flops between two distinct luminosity states: a bright state with a 5-6 Hz quasi-periodic oscillation (QPO) and a dim state showing only strong broadband noise. Despite the marked differences in variability patterns between these states, the spectral energy distributions remain strikingly similar, with only minor changes in the black body component in the soft X-ray range. We find that the QPO frequency correlates with the X-ray count rates and hardness, suggesting a tight coupling between the QPO mechanism and the accretion disc's spectral properties. Additionally, we demonstrate that flip-flops can occur on very short timescales, with almost 50 state changes within ~1200 s, while both states can also remain stable over longer periods (at least 1000 s). We explore various QPO models to explain these observations, including the possibility that the corona's accretion speed is near the sound speed, affecting the presence of QPOs. However, the exact mechanism driving the flip-flops and the QPOs remains unclear. Our findings emphasize the complexity of these phenomena and the necessity for further theoretical and observational studies to unravel the intricacies of QPO and flip-flop behaviours in X-ray binaries.

Although it is commonly assumed that relativistic particles dominate the energy density of the universe quickly after inflation, a variety of well-motivated scenarios predict an early matter-dominated era (EMDE) before the onset of Big Bang nucleosynthesis. Subhorizon dark matter density perturbations grow faster during an EMDE than during a radiation-dominated era, leading to the formation of "microhalos" far earlier than in standard models of structure formation. This enhancement of small-scale structure boosts the dark-matter annihilation rate, which contributes to the heating of the intergalactic medium (IGM). We compute how the dark matter annihilation rate evolves after an EMDE and forecast how well measurements of the 21-cm background can detect dark matter annihilation in cosmologies with EMDEs. We find that future measurements of the global 21-cm signal at a redshift of $z\sim 17$ are unlikely to improve on bounds derived from observations of the isotropic gamma-ray background, but measurements of the 21-cm power spectrum have the potential to detect dark matter annihilation following an EMDE. Moreover, dark matter annihilation and astrophysical X-rays produce distinct heating signatures in the 21-cm power spectrum at redshifts around 14, potentially allowing differentiation between these two IGM heating mechanisms.

Galaxy clusters, the largest gravitationally bound structures in the Universe, contain vast amounts of dark matter, galaxies, and hot ionised gas known as the intracluster medium (ICM). In relaxed cluster cores, the ICM appears to cool radiatively faster than the age of the cluster, but the absence of line emission from the predicted cooling rate suggests heating mechanisms that offset the cooling, with feedback from active galactic nuclei (AGNs) being the most likely source. Turbulence and bulk motions, such as the oscillating (``sloshing'') motion of the core gas in the cluster potential well, have also been proposed as mechanisms for the distribution of heat from the outside of the core. Here we present high-resolution X-ray spectroscopic observations of the core of the Centaurus galaxy cluster with the XRISM satellite. We find that the hot gas is streaming along the line of sight relative to the central galaxy (NGC 4696), with relative velocities varying from 130 km/s to 310 km/s within ~ 30 kpc of the centre, indicating a structured bulk flow ("wind") blowing in the core. This wind is consistent with the core gas sloshing. While the wind may prevent excessive accumulation of cooled gas at the centre of the cluster, it could also distribute the heat injected by the central AGN and/or bring in thermal energy from the surrounding ICM, thus contributing to the thermal balance at the cluster centre. The velocity dispersion (turbulent velocity) of the gas is found to be only ~< 120 km/s (corresponding to a Mach number M ~< 0.2) in the core, even within ~ 10 kpc of the AGN. This may indicate that the influence of the AGN on the motion of the surrounding ICM is limited in the Centaurus cluster.

Collapsars -- massive stars whose cores promptly collapse into black holes (BHs) -- can power long-duration gamma-ray bursts (LGRBs) via relativistic, collimated, electromagnetically-driven outflows, or jets. Their power depends on the BH magnetic field strength and spin. To survive the infalling stellar material, jets need the central BH to attain dynamically important magnetic fields that can suppress the mass inflow and lead to a magnetically arrested disk (MAD). Previous work found that non-radiative MADs can spin down their BHs to an equilibrium spin, $a_{\rm eq}^\text{nr}=0.035-0.07$. Such low spins result in extremely low power jets that may struggle to escape out of the star. However, the dense and hot collapsar disks emit neutrinos that cool the disk, reduce its thickness, and increase the angular momentum supply to the BH. Using 3D two-moment neutrino-transport general relativistic magnetohydrodynamic simulations, we show for the first time that successful collapsar jets powered by neutrino-cooled disks still rapidly spin down their BHs, although to a higher $a_{\rm eq}\approx 0.13$. This value is consistent with LIGO/Virgo/KAGRA inferred spins, is $2-4$x higher than for non-radiative MADs, and results in $4-16$x more powerful LGRB jets, which are more capable of drilling out of the progenitor star. This value of $a_{\rm eq}$ holds across a wide range of progenitor structures and mass accretion rates, $\dot{m} \sim(0.1-10)M_{\odot}/\rm{s}$. We find that for typical LGRB durations, $t\gtrsim30$~s, such BHs consume sufficient mass to reach $a_{\rm eq} \approx 0.13$ by LGRB's end. However, shorter or lower-$\dot{m}$ LGRBs can leave behind more rapidly spinning BHs.

Recent observations by ground-based gamma-ray telescopes have led to the publication of catalogs listing sources observed in the TeV and PeV energy ranges. Photons of such high energy are strongly absorbed during propagation over extragalactic distances, and the catalogs are dominated by Galactic sources. Of particular interest are the observations of the LHAASO telescope, which cover a very broad energy range (from 1 to 10$^3$ TeV) and show that the spectra of all Galactic gamma-ray sources are curved, with significantly different slopes below and above $E \sim 30$ TeV. The cumulative spectrum obtained by summing the contributions of Galactic individual sources has a spectral shape that gradually softens with energy, with a slope that increases from a value of order 2.2 at $E \simeq 1$ TeV, to 2.5 at 30 TeV, and $\simeq 3.4$ at 100 TeV. It is remarkable that the smooth variation in the shape of the cumulative spectrum is obtained from the sum of contributions that have a wide range of shapes. Understanding the origin of the spectral shapes of the Galactic gamma-ray sources is a crucial challenge for high energy astrophysics.

We assume an extreme scenario, in which the arriving cosmic rays are composed of only iron nuclei at energies above $10^{19.6}\,\text{eV}\simeq40\,\text{EeV}$, while allowing a freedom in the scale of the depth of shower maximum ($X_{\rm{max}}$) and preserving the elongation rate and fluctuations of $X_{\rm{max}}$ predicted by models of hadronic interactions. We derive the shift of the $X_{\rm{max}}$ scale for QGSJet II-04 and Sibyll 2.3d models using the public data from the Pierre Auger Observatory. We then propose a new mass-composition model for the energy evolution of four primary species at the ultra-high energies by fitting the publicly-available $X_{\rm{max}}$ distributions. We discuss the consequences of this Heavy-metal scenario on the energy spectrum of individual primary species, hadronic interaction studies, and the effect of the Galactic magnetic field on the arrival directions.

We show that the null geodesic equation for photons is modified in the presence of a charged scalar field, with quantum fluctuations acting as an effective mass term that changes the null paths to timelike curves. This effect can be interpreted as a vacuum polarization phenomenon in curved spacetime. The resulting contribution to the Sachs-Wolfe effect varies with photon frequency, leading to frequency-dependent corrections to the cosmic microwave background (CMB) blackbody spectrum in the form of a $\mu$-distortion, as well as modifications to the CMB power spectrum. We estimate these within a standard inflationary scenario and find that while the correction to the CMB power spectrum is significant when the scalar field is light, the magnitude of the $\mu$-distortion depends strongly on the regularization prescription.

The EXO-UV program is an international, interdisciplinary collaboration between astrophysicists and biologists aimed at expanding the characterization of ultraviolet radiation (UVR) environments on exoplanets. This approach combines astrophysical studies with biological experiments to better understand the potential impacts of UVR on exoplanetary surfaces. UVR is particularly relevant because it reaches the surface of planets and can influence their habitability. The specific wavelengths within the UVR spectrum depend on the planet's atmospheric composition and the spectral energy distribution of its host star. Additionally, high UVR fluxes emitted during flares and superflares are of particular interest due to the limited information available regarding their biological impact. The EXO-UV program has successfully led to the first experimental study examining the biological effects of high UVR fluences, such as those produced by flares and superflares. Future experimental studies aim to investigate the biological effects of repetitive flares. In this paper, we review the latest results from our EXO-UV program.

We describe a model that accounts for the phase rotation that occurs when a receiver or transmitter changes orientation while observing or emitting circularly polarized electromagnetic waves. This model extends work detailing Global Navigation Satellite Systems (GNSS) carrier phase wind-up to allow us to describe the interaction of changing satellite orientation with phase rotation in observing radio telescopes. This development is motivated by, and a critical requirement of, unifying GNSS and Very Long Baseline Interferometry (VLBI) measurements at the observation level. The model can be used for either stationary choke ring antennas or steerable radio telescopes observing either natural radio sources or satellites. Simulations and experimental data are used to validate the model and to illustrate its importance. In addition, we rigorously lay out the feed rotation correction for radio telescopes with beam waveguide and full Nasmyth focuses and validate the correction by observing the effect with dual polarization observations. Using this feed rotation model for beam waveguide telescopes, we produce the first phase delay solution for the VLBI baseline WARK30M-WARK12M. We provide a practical guide to using the feed rotation model in Appendix D.

Using the Large Millimeter Telescope and the SEQUOIA 3~mm focal plane array, we have searched for molecular line emission from two atomic clouds associated with the Fermi Bubble of the Milky Way. Neither 12CO nor 13CO J=1-0 emission is detected from the HI cloud, MW-C20. 12CO J=1-0 emission is detected from MW-C21 that is distributed within 11 clumps with most of the CO luminosity coming from a single clump. However, we find no 13CO emission to a 3sigma brightness temperature limit of 0.3 K. Using this limit and RADEX non local thermodynamic equilibrium (non-LTE) excitation models, we derive H2 column density upper limits of (0.4-3)x10^{21} cm-2 for a set of physical conditions and a H2 to 12CO abundance ratio of 10^4. Model CO-to-H2 conversion factors are derived for each set of physical conditions. We find the maximum value is 1.6x10^{20} cm-2/(K km/s). Increasing [H2/12CO] to 10^5 to account for photodissociation and cosmic ray ionization increases the column density and XCO upper limits by a factor of 10. Applying these XCO limits to the CO luminosities, the upper limit to the total molecular mass in MW-C21 is 132+/-2~Msun, corresponding to less than 27% of the neutral gas mass. For the three clumps that are fully resolved, lower limits to the virial ratios are 288+/-32, 68+/-28, and 157+/-39, which suggest that these structures are bound by external pressure to remain dynamically stable over the entrainment time of 2x10^6 years or are being disrupted by shear and expansion over the clump crossing times of (3-8)x10^5 years. The observations presented in this study add to the growing census of cold gas entrained within the Galactic Center wind.

Near-infrared spectroscopic surveys target high-redshift emission-line galaxies (ELGs) to probe cosmological scenarios. Understanding the clustering properties of ELGs is essential to derive optimal constraints. We present a simple radiative transfer model for spatially resolved galactic H$\alpha$ emission, which includes emission from the warm-hot diffuse interstellar medium. The atomic level populations are in steady-state and computed in the coronal approximation. The model is applied to multiple IllustrisTNG simulations in the redshift range $1\leq z \leq 2$ to produce the luminosity function (LF) and the halo occupation distribution (HOD). Collisional processes account for a significant fraction of $\approx 40\%$ of the total ${\rm H}\alpha$ luminosity ($L_{{\rm H}\alpha}$). Our LFs are in reasonable agreement with measurements from H$\alpha$ surveys if a uniform extinction of $0.3<A_{{\rm H}\alpha}<0.85$ mag is assumed. Our HOD is consistent with that of the ${\it Euclid}$ Flagship galaxy mock up to differences that can be attributed to baryonic feedback, which is absent from the latter. When H$\alpha$ luminosities are computed from an empirical relation between $L_{{\rm H}\alpha}$ and the total star formation rate (SFR) the resulting LFs are in tension with previous observations. Our approach can be extended to other atomic lines, which should be helpful for the mining of high-redshift galaxy spectra in forthcoming surveys.

Data from multiple experiments suggest that the current interaction models used in Monte Carlo simulations do not correctly reproduce the hadronic interactions in air showers produced by ultra-high-energy cosmic rays (UHECR). We have created a large library of UHECR simulations where the interactions at the highest energies are slightly modified in various ways - but always within the constraints of the accelerator data, without any abrupt changes with energy and without assuming any specific mechanism or dramatically new physics at the ultra-high energies. Recent results of the Pierre Auger Observatory indicate a need for a change in the prediction of the models for both the muon content at ground and the depth of the maximum of longitudinal development of the shower. In our parameter space, we find combinations of modifications that are in agreement with this analysis, however a consistent description of UHECR showers remains elusive. Our library however provides a realistic representation of the freedom in the modeling of the hadronic interactions and offers an opportunity to quantify uncertainties of various predictions. This can be particularly valuable for the design of future observatories where hadronic models are often used as input for the prediction of the performance. We demonstrate this powerful capability on several selected examples.

We extend a recently developed dynamically self-consistent model of the Milky Way constrained by observations from the Gaia observatory to include a radially anisotropic component in the dark matter (DM) halo, which represents the debris from the accreted Gaia-Sausage-Enceladus (GSE) galaxy. In the new model, which we call a self-consistent Anisotropic Halo Model or scAHM, we derive distribution functions for DM velocity in heliocentric and geocentric reference frames. We compare them with the velocity distributions in the standard halo model (SHM) and another anisotropic model (SHM++). We compute predicted scattering rates in direct-detection experiments, for different target nuclei and DM particle masses. Seasonal dependencies of scattering rates are analyzed, revealing small but interesting variations in detection rates for different target nuclei and DM masses. Our findings show that the velocity distribution of the anisotropic GSE component significantly deviates from Gaussian, showing a modest impact on the detection rates. The peculiar kinematic signature of the radially anisotropic component would be most clearly observable by direction-sensitive detectors.

At least a third of red giants show a long secondary period (LSP), 5 to 10 times longer than the pulsation period. There is strong evidence that the LSP is caused by eclipses of the red giant by a dust-enshrouded low-mass companion. We have used long-term AAVSO observations of 11 stars to study two aspects of the eclipse hypothesis: the relation between the LSP phase (eclipse) curve and the geometry of the eclipse, and the long-term (decades) changes in the LSP phenomenon in each star. The stars with the largest LSP amplitudes show evidence of a dust tail on the companion, but most of the 11 stars show only a small-amplitude sinusoidal phase curve. The LSP amplitudes of all the stars vary slowly by up to a factor of 8, suggesting that the amount of obscuring dust varies by that amount, but there is no strong evidence that the geometry of the system changes over many decades.

Cosmic Microwave Background (CMB) photons scatter off the free-electron gas in galaxies and clusters, allowing us to use the CMB as a backlight to probe the gas in and around low-redshift galaxies. The thermal Sunyaev-Zel'dovich effect, sourced by hot electrons in high-density environments, measures the thermal pressure of the target objects, shedding light on halo thermodynamics and galaxy formation and providing a path toward understanding the baryon distribution around cosmic structures. We use a combination of high-resolution CMB maps from the Atacama Cosmology Telescope (ACT) and photometric luminous red galaxy (LRG) catalogues from the Dark Energy Spectroscopic Instrument (DESI) to measure the thermal Sunyaev-Zel'dovich signal in four redshift bins from $z=0.4$ to $z=1.2$, with a combined detection significance of 19$\sigma$ when stacking on the fiducial CMB Compton-$y$ map. We discuss possible sources of contamination, finding that residual dust emission associated with the target galaxies is important and limits current analyses. We discuss several mitigation strategies and quantify the residual modelling uncertainty. This work complements closely-related measurements of the kinematic Sunyaev-Zel'dovich and weak lensing of the same galaxies.

An ultraviolet survey of M31 has been carried out during 2017-23 with the UVIT instrument onboard the AstroSat Observatory. Here we present far and near ultraviolet (FUV and NUV) observations from the M31 UVIT survey, which covers a sky area of $\simeq 3.5^\circ \times 1.3^\circ$ with spatial resolution of $\simeq1^{\prime \prime}$. The observations included six filter bands in the wavelength range of 120 nm to 280 nm. Including the six bands, $\simeq$115,000 sources with signal-to-noise S/N$\ge$3 ( $\simeq$95,000 sources with signal-to-noise S/N$\ge$5) were detected at FUV or NUV wavelengths, with the largest set of detections ($\simeq$54,000 sources) in the FUV 150 nm band (F148W filter). This is considerably more than for the first version of the M31 source catalog (published in 2020), in part due to additional observations of M31 by UVIT and in part due to improved data processing. The magnitude (m$_{AB}$) at which incompleteness sets in is $\simeq$23.0 in the F148W band, with the other bands somewhat less sensitive, with least sensitive band (in m$_{AB}$ units) N279N with incompleteness for sources fainter than $\simeq$20.3). The faintest sources detectable in F148W have m$_{AB}\simeq$25.4, with other bands having higher minimum detectable brightness, with N279N having minimum detectable limit of m$_{AB}\simeq$22.1. The product of this work is the new M31 UVIT compact source catalog, containing positions, fluxes , magnitudes and S/N for the sources.

Radio-frequency interference (RFI) presents a significant obstacle to current radio interferometry experiments aimed at the Epoch of Reionization. RFI contamination is often several orders of magnitude brighter than the astrophysical signals of interest, necessitating highly precise identification and flagging. Although existing RFI flagging tools have achieved some success, the pervasive nature of this contamination leads to the rejection of excessive data volumes. In this work, we present a way to estimate an RFI emitter's altitude using near-field corrections. Being able to obtain the precise location of such an emitter could shift the strategy from merely flagging to subtracting or peeling the RFI, allowing us to preserve a higher fraction of usable data. We conduct a preliminary study using a two-minute observation from the Murchison-Widefield Array (MWA) in which an unknown object briefly crosses the field of view, reflecting RFI signals into the array. By applying near-field corrections that bring the object into focus, we are able to estimate its approximate altitude and speed to be $11.7$ km and $792$ km/h, respectively. This allows us to confidently conclude that the object in question is in fact an airplane. We further validate our technique through the analysis of two additional RFI-containing MWA observations, where we are consistently able to identify airplanes as the source of the interference.

The first year results of DESI provide evidence that dark energy may not be quantum vacuum energy ($\Lambda$). If true, this would be an extraordinary development in the 25-year quest to understand cosmic acceleration. The best-fit DESI $w_0w_a$ models for dark energy, which underpin the claim, have very strange behavior. They achieve a maximum dark energy density around $z\simeq 0.4$ and rapidly decrease before and after. We explore physics-motivated models where the dark energy is a rolling scalar-field. Each of our four scalar-field models is characterized by one dimensionless parameter $\beta$, which in the limit of $\beta \rightarrow 0$ reduces to $\Lambda$CDM. While none of our models fit the DESI data significantly better than $\Lambda$CDM, for values of $\beta$ of order unity, they fit about as well as $\Lambda$CDM. Each scalar field model makes different predictions for the age of the Universe, which might be used to discriminate amongst them. For small values of $\beta$, the dimensionsless initial slope of the scalar field potential links the predictions of different scalar field models. And for small values of $\beta$, $w_0w_a$ models can marginally represent the predictions of a scalar-field model at the current precision needed. However, with increasingly precise distance measurements, over a larger redshift range, explicit modeling of the scalar-field evolution is already and will continue to be essential to testing alternatives to $\Lambda$.

We homogeneously investigate the morphological properties of $169$ galaxies at $z\sim10-16$ with deep JWST NIRCam images employing our established techniques of GALFIT modeling and uncertainty evaluation (systematics+statistics). We obtain effective radii $r_{\rm e}$ ranging $20-500$ pc, with a distribution significantly broader than the scatter made by the uncertainties. We find that the $r_{\rm e}$ distribution is well described by a log-normal distribution with a mean of $r_{\rm e}=133^{+13}_{-12}$ pc and a standard deviation of $\sigma_{{\rm ln}r_{\rm e}} = 0.52 \pm 0.08$. The standard deviation is comparable to that of local galaxies, indicating no significant evolution over $z\sim 0-10$. We estimate the virial radius $r_{\rm vir}$ from the stellar masses via the star-formation main sequence and stellar-to-halo mass relation, obtaining a stellar-to-halo size ratio $r_{\rm e}/r_{\rm vir} = 0.015^{+0.015}_{-0.005}$, which is comparable to those of star-forming galaxies in the local and low-$z$ Universe. Our results of 1) the log-normal $r_{\rm e}$ distribution, 2) the standard deviation value, and 3) a mean radial profile consistent with an exponential profile ($n=1.3\pm0.6$) suggest that galaxies at $z\sim10-16$ generally follow the classical galaxy disk formation scenario with a specific disk angular momentum fraction of $j_{\rm d} / m_{\rm d} \sim 0.5-1$. Interestingly, we identify two remarkable outliers GN-z11 ($z_{\rm spec}=10.60$) and GHZ2 ($z_{\rm spec}=12.34$) with $r_{\rm e}=55^{+5}_{-6}$ pc and $39\pm11$ pc, respectively, that may not be explained by disk structures but by AGN or compact star-forming galaxies merging underway in short periods of time, as reproduced in numerical simulations.

Neutrinos act as probes of hadronic processes and offer a distinctive view into their astrophysical origins at high energies. When reaching energies on the PeV scale, $\nu_\tau$ interactions within the Earth can produce a significant flux of $\tau$-leptons. These $\tau$-leptons subsequently decay, generating upward-moving extensive air showers (EAS). Using the Earth as a target for neutrinos and the atmosphere as a signal generator effectively creates a detector with a mass $\gg$ gigaton. $\nu$SpaceSim is a comprehensive simulation developed to model all the relevant physical processes that describe the neutrino-induced, Earth-emergent lepton chain. The simulation models neutrino interactions inside the Earth that produce leptons, the propagation of the leptons through the Earth into the atmosphere, and their decay, forming composite EAS. Next, it models the generation of air optical Cherenkov and radio signals from these showers, including the propagation and attenuation of these signals through the atmosphere, accounting for effects such as clouds and the ionosphere. Finally, the simulation models the detector response according to the parameters defined by the user (such as altitude, effective area, frequency band...). Through this end-to-end simulation, $\nu$SpaceSim aims to help design the next generation of balloon- and space-based experiments, to estimate the exposure of ground-based experiments to these showers, and to understand the data from recent experiments such as EUSO-SPB2 and ANITA.

Axions are one of the leading dark matter candidates. If we are embedded in a Milky Way dark matter halo comprised of axions, their stimulated decay would enable us to observe a counterimage (``axion gegenschein") with a frequency equal to half the axion mass in the opposite direction of a bright radio source. This spectral line emission will be broadened to $\Delta \nu/\nu \sim \sigma_d/c \sim 10^{-3}$ due to the velocity dispersion of dark matter, $\sigma_d$. In this pilot study, we perform the first search for the expected axion gegenschein image of Vela supernova remnant (SNR) with 26.4 hours of effective ON-OFF data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) L-band (1.0 - 1.5~GHz) 19-beam receiver. Our null detection limits the axion-photon coupling strength to be $g_{a\gamma\gamma} \lesssim 2 \times 10^{-10} \mathrm{GeV}^{-1}$ in the mass ranges of $8.7\,\mu\mathrm{eV} \leq m_a \leq 9.44\,\mu\mathrm{eV}$ and $10.85\,\mu\mathrm{eV} \leq m_a \leq 12.01\,\mu\mathrm{eV} $. These results provide a stronger constraint on $g_{a\gamma\gamma}$ in this axion mass range than the current limits obtained by the direct search of axion decay signal from galaxy clusters which uses FAST observations, but is a factor of $\sim 3$ times weaker than the current CAST this http URL on our observation strategy, data processing methods, and results, the expected sensitivity will reach $\sim 10^{-11}\mathrm{GeV}^{-1}$ with $\sim 2000$ hours of observation in the future.

We report the results of deep H-alpha and [O III] images of the bright WN7/WC4 Wolf-Rayet star WR 8 (HD 62910). These data show considerably more surrounding nebulosity than seen in prior imaging. The brighter portions of the nebula span 6' in diameter and exhibit considerable fine-scale structure including numerous emission clumps and bright head-tail like features presumably due to the effects of the WR star's stellar winds. Due to the overlap of a relatively bright band of unrelated foreground diffuse interstellar H-alpha emission, WR 8's nebula is best viewed via its [O III] emission. A faint 9' x 13' diffuse outer nebulosity is detected surrounding the nebula's main ring of emission. The nebula's optical structure is substantially different from that of its thermal continuum dust emission seen in WISE 22 micron infrared images which show a smaller and sharply defined emission shell.

In protoplanetary disks, the water snowline marks the location where ice-rich pebbles sublimate, releasing silicate grains and water vapor. These processes can trigger pile-ups of solids, making the water snowline a promising site for forming planetesimals. However, previous studies exploring the pile-up conditions typically employ 1D, vertically-averaged and isothermal assumptions. In this work, we investigate how a 2D flow pattern and realistic temperature structure affect the pile-up of pebbles at the snowline and how latent heat effects can leave observational imprints. We perform 2D (R-Z) multifluid hydrodynamic simulations, tracking chemically heterogeneous pebbles and the released vapor. With a recent-developed phase change module, the mass transfer and latent heat exchange during ice sublimation are calculated self-consistently. The temperature is calculated by a two-stream radiation transfer method under various opacities and stellar luminosity. We find that vapor injection at the snowline drives a previously unrecognized outflow, leading to a pile-up of ice outside the snowline. Vapor injection also decreases the headwind velocity in the pile-up, promoting planetesimal formation and pebble accretion. In active disks, we identify a water-cycle: after ice sublimates in the hotter midplane, vapor recondenses onto pebbles in the upper, cooler layers, which settle back to the midplane. This cycle promotes ice-trapping at snowline. Latent heat exchange flattens the temperature gradient across the snowline, broadening the width while reducing the peak solid-to-gas ratio of pile-ups. Due to the water cycle, active disks are more conducive to planetesimal formation than passive disks. The significant temperature dip (~ 40K) caused by latent heat cooling manifests as an intensity dip in the dust continuum, presenting a new channel to identify the water snowline in outbursting systems.

Accurate interpretation of observations relies on the interstellar dust extinction law, which also serves as a powerful diagnostic for probing dust properties. In this study, we investigate the multi-wavelength extinction law of the quiescent, starless molecular cloud Coalsack and explore its potential variation across different interstellar environments: the surrounding region, the nearby high Galactic latitude region, the inner dense region, and the inner diffuse region. Using a sample of 368,524 dwarf stars selected from Gaia DR3 as tracers, we establish the effective temperature Teff-intrinsic color relations to derive the intrinsic color indices and optical-mid-infrared (MIR) color excess (CE) for 20 bands. Linear fits to the CE-CE diagrams provide color excess ratios (CERs), which are subsequently converted into relative extinction. The resulting extinction curves for different environments exhibit steep slopes in the near-infrared (NIR) and flat profiles in the MIR. In the optical-NIR range, the Coalsack extinction law is consistent with R_V = 3.1 while in the MIR it follows R_V= 5.5 similar to the results of active star-forming clouds. At an angular resolution of 1.3', our extinction map reveals fine cloud structures. No correlation is found between R_V and E(B-V) for E(B-V) > 0.3 mag, implying a uniform optical extinction law in the Coalsack cloud. The derived average R_V value is 3.24.

Simulating Population (Pop.) III star formation in mini-halos in a large cosmological simulation is an extremely challenging task but it is crucial to estimate its impact on the 21cm power spectrum. In this work, we develop a framework within the semi-analytical code meraxes to estimate the radiative backgrounds from Pop. III stars needed for the computation of the 21cm signal. We computed the 21cm global signal and power spectrum for different Pop. III models varying star formation efficiency, initial mass function (IMF) and specific X-ray luminosity per unit of star formation (LX/SFR). In all the models considered, we find Pop. III stars have little to no impact on the reionization history but significantly affect the thermal state of the intergalactic medium (IGM) due to the strong injection of X-ray photons from their remnants that heat the neutral IGM at $z \geq$ 15. This is reflected not only on the 21cm sky-averaged global signal during the Cosmic Dawn but also on the 21cm power spectrum at $z \leq$ 10 where models with strong Pop. III X-ray emission have larger power than models with no or mild Pop. III X-ray emission. We estimate observational uncertainties on the power spectrum using 21cmsense and find that models where Pop. III stars have a stronger X-ray emission than Pop. II are distinguishable from models with no or mild Pop. III X-ray emission with 1000 hours observations of the upcoming SKA1-low.

We present [NII] 205 $\mu$m fine structure line observations of three submillimeter galaxies (SMGs) and three quasar host galaxies at 4$\lesssim$z$\lesssim$6 using the Institut de radioastronomie millimetrique (IRAM) interferometer. The [NII] emission is detected in three sources, and we report detections of the underlying dust continuum emission in all sources. The observed [NII]-to-infrared luminosity ratio spans at least 0.5 dex for our sources. Comparing our estimates with sources detected in the [NII] 205 $\mu$m at similar redshifts shows that the overall [NII]-to-IR luminosity ratio spans over a dex in magnitude from L$_{[NII]}$/L$_{IR}$ ~ 10$^{-4}$ - 10$^{-5}$ and follows the trend of the so-called [NII] fine structure line deficit observed in (ultra)-luminous infrared galaxies in the local Universe. The [CII]-to-[NII] luminosity ratio is >10 for most of our sources, indicating that the bulk of the [CII] 158 $\mu$m line emission (f([CII]$^{PDR}$)>75%) arises from the neutral medium. From our analysis, we do not find significant differences in the [NII] 205 $\mu$m emission and the respective ratios between SMGs and QSOs, suggesting a negligible contribution to the boosting of [NII] 205 $\mu$m emission due to the active galactic nucleus (AGN) photoionization. Future investigations involving other fine structure lines and optical diagnostics will provide further insight into a suite of ionized medium properties and reveal the diversity between AGN and non-AGN environments.

The results of a study of the accuracy characteristics and image quality on the SAO RAS optical telescopes, Zeiss-1000 and BTA, using the recently developed "Telescope Analyzer" device are described: a method for determining the coefficients of the pointing correction system, the position of the aberration axis along the coma in images of star fields, natural frequencies of vibrations of mechanical systems, prospects for the development of the device. Attention is paid to the thermal deformations of the BTA main mirror and measures to reduce them. Mention is made of systems being developed for partial correction of wavefront aberrations due to imperfect mechanics, and plans to modernize the control system of the BTA. The complex of 0.5-meter telescopes "Astro-M" has not been forgotten: hardware and software solutions for automating the first and second telescopes, plans for commissioning of telescopes No 3-5 are described. Links to repositories with developed software and hardware products are provided.

We present a novel method for Cosmic Microwave Background (CMB) foreground removal based on deep learning techniques. This method employs a Transformer model, referred to as \texttt{TCMB}, which is specifically designed to effectively process HEALPix-format spherical sky maps. \texttt{TCMB} represents an innovative application in CMB data analysis, as it is an image-based technique that has rarely been utilized in this field. Using simulated data with noise levels representative of current ground-based CMB polarization observations, the \texttt{TCMB} method demonstrates robust performance in removing foreground contamination. The mean absolute variance for the reconstruction of the noisy CMB Q/U map is significantly less than the CMB polarization signal. To mitigate biases caused by instrumental noise, a cross-correlation approach using two half-mission maps was employed, successfully recovering CMB EE and BB power spectra that align closely with the true values, and these results validate the effectiveness of the \texttt{TCMB} method. Compared to the previously employed convolutional neural network (CNN)-based approach, the \texttt{TCMB} method offers two significant advantages: (1) It demonstrates superior effectiveness in reconstructing CMB polarization maps, outperforming CNN-based methods. (2) It can directly process HEALPix spherical sky maps without requiring rectangular region division, a step necessary for CNN-based approaches that often introduces uncertainties such as boundary effects. This study highlights the potential of Transformer-based models as a powerful tool for CMB data analysis, offering a substantial improvement over traditional CNN-based techniques.

Large-scale anisotropy, with amplitudes reaching approximately 0.1% at TeV energies, has been observed by multiple cosmic-ray experiments. The obstruction of cosmic rays by the Sun and Moon creates shadow effects, potentially impacting the observed cosmic ray anisotropy. To evaluate these effects, this study calculates the contributions of the Sun's and Moon's shadows to the overall cosmic-ray anisotropy in both local solar and sidereal time. The analysis reveals that in local sidereal time, the total 1D projection amplitude of the anisotropy is around 0.003%, which is significantly smaller than the observed cosmic-ray anisotropy. This indicates that the influence of the Sun's and Moon's shadows on cosmic-ray anisotropy analysis in local sidereal time is negligible. In contrast, in local solar time, the shadow-induced deficit appears in a very small time bin, with a magnitude comparable to that of the cosmic-ray solar anisotropy. This deficit could serve as a benchmark for validating anisotropy measurements in future facilities.

The relationship between an active galactic nucleus (AGN) and its host galaxy is still far from being understood. Properties of the host galaxies of Seyfert nuclei, such as luminosity concentration, morphological type, metallicity, and age of the stellar population are expected to be related with nuclear activity -- either at the epoch of galaxy formation or in the present days via feeding of the central black-hole. In this paper we investigate whether stellar ages and metallicities are linked to the activity within the nucleus in a sample of AGN of various types. Our sample includes seven AGN, from Seyfert 1 to LINERs, observed with VLT/ISAAC and VLT/SINFONI. Based on an inverse method using a stellar library, we analyse H band infrared spectra, in a wavelength region devoid of emission lines, at a spectral resolution of about 3000, in the central few 100 pc. HST images are used to visualise the regions defined in each galaxy. For each galaxy, we give the results of the spectral synthesis, in particular the percentages of the stellar, power law and blackbody continua, and the percentages of various stellar types that account for the stellar lines. Out of the seven galaxies, three show strong and recent star formation in the inner 100 pc, while no star formation is detected in the three genuine Seyfert 2 galaxies. Beyond a radius of 100 pc, all show more or less recent star formation. Moreover we can conclude that the star formation history of the inner nucleus is highly heterogeneous.

One of the primary goals of Neutron Star Interior Composition Explorer (NICER)-like X-ray missions is to impose stringent constraints on the neutron star equation of state by precisely measuring their masses and radii. NICER has recently expanded the dataset of inferred mass-radius relations for neutron stars, including four rotation-powered millisecond pulsars PSR J0030+0451, PSR J0740+6620, PSR J0437-4715, and PSR J1231-1411. In this work, the mass-radius relation and X-ray emitting region properties of PSR J1231-1411 are inferred with an independent pulse profile modeling based on the spherical star Schwarzschild-spacetime and Doppler approximation. With one single-temperature elongated hot spot and one single-temperature crescent hot spot, the inferred gravitational mass is $M = 1.12 \pm 0.07 M_{\odot}$ and the inferred equatorial radius is $R_{eq} = 9.91_{-0.86}^{+0.88}$ km (68% credible intervals). It provides an alternative geometry configuration of the X-ray emitting region for PSR J1231-1411 to sufficiently explain the observation data of NICER and XMM-Newton. The inferred radius is smaller than that derived by \citet{salmi2024nicer} ($M = 1.04_{-0.03}^{+0.05} M_{\odot}$, $R_{eq} = 12.6 \pm 0.3$ km), and the inferred mass is slightly higher in this work. The inferred geometry configurations of the X-ray emitting region in both works are non-antipodal, which is not consistent with a centered dipole magnetic field and suggests a complex magnetic field structure.

This paper describes the new Globular Clusters GMRT Pulsar Search (GCGPS) survey. This survey aims to find MSPs in the globular clusters (GCs) of the Milky Way using uGMRT. The observations use the uGMRT's Band-4 (550$-$750 MHz) and Band-3 (300$-$500 MHz) receivers, which are well suited for steep-spectral-index radio sources like MSPs; the survey will eventually cover the GCs accessible to the uGMRT sky (i.e. $\delta\:>\:\sim\:-\:53^\circ$), and that is South of $\delta = -17^\circ$ (FAST sky limit) and have not been targeted with the sensitivity of this survey. The observations started in May 2023, having so far resulted in seven new discoveries. In this paper, we present the discovery and follow-up study of the first pulsar from this survey, J1617$-$2258A, a 4.32 ms binary MSP that is also the first to be discovered in the globular cluster NGC 6093. We localised this MSP with arc-sec precision from imaging and obtained the unique timing solution from more than one year of timing observations with the Band-4 (550$-$750 MHz) receivers of the uGMRT. This revealed an unusual binary MSP, with a $\sim$ 19-hour, highly eccentric (e $\sim$ 0.54) orbit having a low-mass companion. This orbital eccentricity allowed the measurement of the rate of advance of periastron for this system, which led to the derivation of its total mass, $1.67 \, \pm \, 0.06 \, \rm M_{\odot}$; this together with the system's mass function implies, for the pulsar and the companion, $M_\mathrm{p} < 1.60 \, \rm M_{\odot}$ and $M_\mathrm{c} > 0.072 \, \rm M_{\odot}$. The system is likely a perturbed MSP-Helium WD system seen at a low orbital inclination.

Due to the inhomogeneity of electron number density, radio waves emitted by pulsars undergo scattering as they pass through the interstellar medium (ISM). However, a connection between large-scale pulsar scattering data and the structure of the Galactic ISM has yet to be established. In this paper, we explore the capability of pulsar scattering time data in discovering structures in the ISM. Using a large dataset of scattering time measurements for 473 pulsars, we fit the pulsar reduced scattering intensity as a function of Galactic latitude and distance, constructing a smooth model of the Galactic pulsar scattering distribution. By comparing this smooth distribution with observational data, we identify two ISM structures responsible for pulsar scattering, one is associated with the Vela supernova remnant region within the Gum Nebula, while the other is a newly discovered structure -- a distant superbubble, G38, located at a distance of 2.3 kpc with a size of ~50 pc. Analysis of the correlation coefficient of the pulsar scattering distribution shows that the correlation is dominated by structures smaller than 0.15 kpc -- the closest separation approachable by the current dataset. As measurements of the pulsar scattering time continue to increase in the future, they can potentially become an independent tool for exploring structures in the ISM.

Billions of isolated stellar-mass black holes (IBHs) are thought to wander through the interstellar medium (ISM) in the Galaxy, yet only one has been detected. IBHs embedded in ISM would accrete gas via Bondi-Hoyle-Littleton accretion, and with efficient magnetic flux accumulation, the magnetosphere would be formed in the vicinity of IBHs. We explore the detectability of such IBHs through high-energy gamma rays from spark gaps in their magnetospheres based on our recent numerical simulation. The gap gamma rays can be bright at the GeV-TeV energies when IBHs are in the dense ISM. About $10^3$ and $10$ IBHs might be contained in unidentified objects of the $\textit{Fermi}$ Large Area Telescope and the High Energy Stereoscopic System, respectively. A future Galactic plane survey by the Cherenkov Telescope Array Observatory would lead to $\sim10^2$ detections. We also evaluate the combined gamma-ray emission of IBHs in the Galaxy and find that the IBHs may contribute to the Galactic diffuse gamma rays. IBHs will emit optical and X-ray photons from their accretion disk as counterparts, potentially useful for identifying candidates.

Context. Long gamma-ray bursts (LGRBs) are generally observed in low-metallicity environments. However, 10 to 20 per cent of LGRBs at redshift $z<2$ are associated with near-solar to super-solar metallicity environments, remaining unexplained by traditional LGRB formation pathways that favour low metallicity progenitors. Aims. In this work, we propose a novel formation channel for LGRBs that is dominant at high metallicities. We explore how a stripped primary star in a binary can be spun up by a second, stable reverse-mass-transfer phase, initiated by the companion star. Methods. We use POSYDON a state-of-the-art population synthesis code that incorporates detailed single- and binary-star mode grids, to investigate the metallicity dependence of the stable reverse-mass-transfer LGRB formation channel. We determine the available energy to power an LGRB from the rotational profile and internal structure of a collapsing star, and investigate how the predicted rate density of the proposed channel changes with different star formation histories and criteria for defining a successful LGRB. Results. Stable reverse mass transfer can produce rapidly rotating, stripped stars at collapse. These stars retain enough angular momentum to account for approximately 10-20% of the observed local LGRB rate density, under a reasonable assumption for the definition of a successful LGRB. However, the local rate density of LGRBs from stable reverse mass transfer can vary significantly, between 1 and 100 Gpc$^{-3}$ yr$^{-1}$, due to strong dependencies on cosmic star formation rate and metallicity evolution, as well as the assumed criteria for successful LGRBs.

We analyze PSR J0952-0607, the most massive and fastest spinning neutron star observed to date, to refine constraints on the neutron star equation of state (EoS) and investigate its robustness against r-mode instabilities. With a mass of \( 2.35 \pm 0.17 \, M_{\odot} \) and a spin frequency of 709.2 Hz, PSR J0952-0607 provides a unique opportunity to examine the effects of rapid rotation on the structure of a neutron star. Using a Bayesian framework, we incorporate the rotationally corrected mass of PSR J0952-0607, alongside PSR J0740+6620's static mass measurement, to constrain the EoS. Our findings demonstrate that neglecting rotational effects leads to biases in the inferred EoS, while including the neutron star spin produces tighter constraints on pressure-density and mass-radius relations. Additionally, we explore the r-mode instability window for PSR J0952-0607 under the assumption of both rigid and elastic crust models and find that a rigid crust allows a higher stable temperature range, whereas an elastic crust places the star within the instability window under certain thermal insulation conditions.

We investigate the impact of peculiar motion of Type Ia supernova host galaxies on cosmological parameter estimation. This motion causes their redshift to deviate from that of the comoving observer at their position and is a source of noise. To this end, we develop an estimator for parameter estimation in models with errors in independent variables. Using the Bayesian framework, errors in independent variables are treated as nuisance parameters by making the independent variables parameters of the model. Our method applied to the Pantheon sample of Type Ia supernova indicates a few percent shift in the central values of inferred cosmological parameters. For the $w$CDM model, we find that accounting for peculiar velocities makes the data marginally more consistent with the cosmological constant model. By using simulated data, we show that not accounting for peculiar velocities will significantly impact parameter estimation from higher precision future data sets.

We employ a Conditional Variational Autoencoder (CVAE) for parameter inference on massive black hole binaries (MBHBs), considering joint observations from a network of three space-based gravitational wave detectors. Our result demonstrates that the trained CVAE model can estimate the posterior distribution of source parameters in approximately 0.5 seconds, while the standard Bayesian sampling method, utilizing parallel computation across 16 CPU cores, takes an average of 22 hours across 25 MBHB signals. While the CVAE model achieves remarkable efficiency, its estimated distributions exhibit slight differences in shape compared to the standard Bayesian results, particularly showing lighter tails with broader widths. By using CVAE result to constrain the prior range for Bayesian sampling, we reduce the sampling time to $14.0\%$ of the original runtime on average, while maintaining similar Bayesian result.

Accurate limb-darkening models are needed for accurate characterisation of eclipsing binary stars and transiting exoplanets from the analysis of their light curves. The limb-darkening observed in solar-type stars from the analysis of light curves for transiting hot-Jupiter exoplanets are systematically less steep than predicted by stellar model atmospheres that do not account for the stellar magnetic field. Hot-Jupiter host stars tend to be metal rich ([Fe/H] ~0.25) leading to a lack of low- and solar-metallicity targets in previous studies, so we have analysed the TESS light curves for a sample of 19 stars with transiting M-dwarf companions to extend the range of limb-darkening measurements to [Fe/H] values more typical for solar-type stars. We find that the systematic offset between the observed and predicted limb-darkening profiles observed in metal-rich hot-Jupiter systems is also observed for these solar-type stars at lower metallicity. These observations provide additional measurements to explore the impact of magnetic fields on the atmospheres of solar-type stars. We have also used the TESS light curves to make precise estimates of the radius and effective temperature of the M-dwarf companions in these 19 binary systems. We confirm the results from previous studies that find very low mass stars tend to be about 3 per cent larger than predicted by stellar models that use a mixing length prescription calibrated on the Sun.

We derive the gravitational-wave (GW) strain upper limits from resolvable supermassive black-hole binaries using the data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), in the context of the Chinese Pulsar Timing Array project. We focus on circular orbits in the $\mu$Hz GW frequency band between $10^{-7}$ and $3\times10^{-6}$ Hz. This frequency band is higher than the traditional pulsar timing array band and is less explored. We used the data of the millisecond pulsar PSR J1713+5307 observed between August 2019 and April 2021. A dense observation campaign was carried out in September 2020 to allow for the $\mu$Hz band coverage. Our sky-average continuous source upper limit at the 95% confidence level at 1$\mu$Hz is 1.26$\times10^{-12}$, while the same limit in the direction of the pulsar is 4.77$\times10^{-13}$.

To study the role of the feedback from the Active Galactic Nuclei (AGNs) in the evolution of its host galaxy, we need observational constraints on 100 pc scales. We used the Gemini Near Infrared Integral Field Spectrograph in the J and K bands at a spatial resolution of 100 pc and spectral resolution of 45 km\,s$^{-1}$ to observe the central region of the Seyfert galaxy NGC1125. Emission-line flux distributions in ionized and molecular gas extends up to $\approx$ 300\,pc from the nucleus, where they are found to peak. The Pa$\beta$ and [Fe\,{\sc ii}]$\lambda$1.2570$\mu$m emission-lines show two components: a narrow and a broad. The narrow component is preferably extended from the north-east to the south-west, while the broad component is perpendicular to it. Their kinematics are also different, with the narrow component showing a rotation pattern, with low velocity dispersion values ($\sigma$ $\approx$ 140 km s$^{-1}$) and the broad component a disturbed velocity field and high values of $\sigma$ ($\approx$ 250 km s$^{-1}$). We interpreted the narrow component velocity fields as due to gas rotating in the galaxy plane and fitted rotation velocity models to it, plus an outflow component in the ionized gas. The broad component is interpreted as an outflow, with mass outflow rate in the range of 0.6 to 1.1 M$_{\sun}$ yr$^{-1}$, with an outflow power ranging from 3.9$\times$10$^{40}$ to 1.1$\times$10$^{41}$ erg\,s$^{-1}$, which represents 0.07\% and 0.2\% of the bolometric luminosity of the AGN. There is an explicit relation between the shock ionized outflow and the low-luminosity radio source.

We utilized archived data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) to analyze the single-pulse profile morphology of PSR J1935$+$1616 (B1933$+$16). The results show that PSR J1935$+$1616 exhibits significant micropulses as well as various changes in single-pulse profile morphology. In the FAST archived data, a total of 969 single pulses with microstructure were identified, accounting for 9.69$\%$ of the total pulse sample, with characteristic widths of $127.63^{+70.74}_{-46.25}$ $\mu$s. About half of these pulses display quasiperiodic micropulses, with a periodicity of 231.77 $\pm$ 9.90 $\mu$s. Among the 520 single pulses with quasiperiodic microstructure, 208 also exhibit quasiperiodicity in circular polarization, with a characteristic period of $244.70^{+45.66}_{-21.05}$ $\mu$s. The micropulse characteristic width in circular polarization is 106.52 $\pm$ 46.14 $\mu$s. Compared to normal pulses, the relative energy (E/<E>) of single pulse with microstructure follows a double Gaussian distribution, while that of normal pulses follows a single Gaussian distribution. Based on the intensity of the leading and trailing components in the single-pulse profile morphology of PSR J1935+1616, we classified the pulses into four morphological modes (A, B, C, and D). The relative energy distribution of pulses in mode A is significantly different from the others, following a double Gaussian distribution, while the relative energy distributions in modes B, C, and D follow a single Gaussian distribution. Our study also suggests a possible correlation between micropulses and single-pulse profile morphology. Single pulse with micropulses are most likely to occur in mode A, while their occurrence is least likely in mode D.

Isolated wide binary stars provide natural laboratories to directly test or measure weak gravity for Newtonian acceleration $g_{\rm{N}}\lesssim 10^{-9}$ m s$^{-2}$. Recent statistical analyses of wide binaries have been performed only with sky-projected relative velocities $v_p$ in the pairs. A new method of Bayesian orbit modeling exploiting three relative velocity components including the radial (line-of-sight) component $v_r$ is developed to measure a gravitational anomaly parameter $\Gamma\equiv\log_{10}\sqrt{G_{\rm{eff}}/G_{\rm{N}}}$ where $G_{\rm{eff}}$ is the effective gravitational constant for pseudo-Newtonian elliptical orbits, while $G_{\rm{N}}$ is Newton's constant. The method infers individual probability distributions of $\Gamma$ and then combines the independent distributions to obtain a consolidated distribution in a specific range of $g_{\rm{N}}$. Here the method is described and applied to a sample of 312 wide binaries in a broad dynamic range $10^{-11.0}\lesssim g_{\rm{N}}\lesssim 10^{-6.7}$ m s$^{-2}$ with $v_r$ uncertainties in the range $168<\sigma_{v_r}<380$ m s$^{-1}$ selected from the Gaia DR3 database. The following results are obtained: $\Gamma = 0.000\pm 0.011$ ($N_{\rm{binary}}=125$) for a high acceleration regime ($10^{-7.9} \lesssim g_{\rm{N}} \lesssim 10^{-6.7}$ m s$^{-2}$) agreeing well with Newton, but $\Gamma = 0.085\pm 0.040$ (35) for a MOND regime ($10^{-11.0}\lesssim g_{\rm{N}}\lesssim 10^{-9.5}$ m s$^{-2}$) and $\Gamma = 0.063\pm 0.015$ (111) for a MOND+transition regime ($10^{-11.0}\lesssim g_{\rm{N}}\lesssim 10^{-8.5}$ m s$^{-2}$). These results show that gravitational anomaly is evident for $g_{\rm{N}}\lesssim 10^{-9}$ m s$^{-2}$ and $\Gamma$ in the MOND regime ($\lesssim 10^{-9.5}$ m s$^{-2}$) agrees with the first-tier prediction ($\approx 0.07$) of MOND gravity theories.

To date, gas phase observations of sulphur in dense interstellar environments have only constrained the molecular carriers of 1% of its predicted cosmic abundance. An additional 5% is known to be locked up in molecular solids in dense clouds, leaving the main reservoir of depleted sulphur in the solid phase unknown. The spectral resolution and sensitivity of the JWST could make a substantial difference in detecting part of this missing sulphur, with its wavelength coverage that includes vibrational absorption features of the S-carriers H2S, OCS, SO2, CS2, SO, CS, and S8. The aim of this study is to determine whether these molecules may be viable candidates for detection. We carried out new laboratory measurements of the IR absorption spectra of CS2 and S8 to update the IR band strength of the most intense CS2 absorption feature at 6.8 {\mu}m, as well as to determine that of S8 at 20.3 {\mu}m for the first time. These data, along with values previously reported in the literature, allow us to evaluate which S-bearing species could be potentially detected with JWST in interstellar ices. Taking the literature abundances of the major ice species determined by previous IR observations towards starless cores, LYSOs and MYSOs, we generated simulated IR spectra using the characteristics of the instruments on the JWST. Thus, we have been able to establish a case study for three stages of the star formation process. We conclude that the detection of S-bearing molecules remains challenging. Despite these obstacles, the detection of H2S and potentially SO2 should be possible in regions with favourable physical and chemical conditions. In contrast, S8 would remain undetected. Although the sensitivity of JWST is insufficient to determine the sulphur budget in the solid state, the detection of an additional icy sulphur compound (H2S, SO2) would enable us to elevate our knowledge of sulphur chemistry.

M dwarfs are important targets in the search for Earth-like exoplanets due to their small masses and low luminosities. Several ongoing and upcoming space missions are targeting M dwarfs for this reason, and the ESA PLATO mission is one of these. In order to fully characterise a planetary system the properties of the host star must be known. For M dwarfs we can derive effective temperature, surface gravity, metallicity, and abundances of various elements from spectroscopic observations in combination with photometric data. The Stellar Abundances and atmospheric Parameters Pipeline (SAPP) has been developed as a prototype for one of the stellar science softwares within the PLATO consortium, it is aimed at FGK stars. We have modified it to be able to analyse the M dwarf among the PLATO targets. The current version of the pipeline for M dwarfs mostly relies on spectroscopic observations. The data processing is based on the machine learning algorithm The Payne and fits a grid of model spectra to an observed spectrum to derive effective temperature and metallicity. We use spectra in the H-band, as the near-infrared region is beneficial for M dwarfs. A method based on synthetic spectra was developed for the continuum normalisation of the spectra, taking into account the pseudo-continuum formed by numerous lines of the water molecule. Photometry is used to constrain the surface gravity. We tested the modified SAPP on spectra of M dwarfs from the APOGEE survey. Our validation sample of 26 stars includes stars with interferometric observations and binaries. We found a good agreement between our values and reference values from a range of studies. The overall uncertainties in the derived effective temperature, surface gravity, and metallicity is 100 K, 0.1 dex, and 0.15 dex, respectively. We find that the modified SAPP performs well on M dwarfs and identify possible areas of future development.

We quantify the effect of starspots for the orbital elements of the spotted RS CVn binary $\lambda$ Andromedae ($\lambda$ And) and present an empirical correction. The aim is to obtain a more precise orbital solution that can be used to better study the system's severe orbital-rotational asynchronism. Phase-resolved high-resolution optical spectra were recorded over the course of 522 days in 2021-2022. We employed two facilities with medium and high resolution spectroscopy for the multiple activity analyses. Doppler imaging is used to reconstruct $\lambda$ And's starspots with a high resolution (R= 250 000) and high signal-to-noise ratio spectra. Optimized cross-correlation functions were used to measure precise radial velocities at a level of a few ten's of m/s. The spot-corrected radial velocities enable, on average, a threefold increase in precision of the individual orbital elements. The residual velocity jitter with a full range of 500 m/s is modulated by the rotation period of $\lambda$ And of 54.4$\pm$0.3 days. Our logarithmic gravity from spectrum synthesis of 2.8$\pm$0.2 together with the interferometrically determined stellar radius suggest a most-likely mass of the primary of $\approx$1.4 Msun. The small orbital mass function then implies a secondary mass of just $\approx$0.1 Msun, which is appropriate for an L-class brown dwarf. The Doppler image reconstructs a dominating cool spot with an umbral temperature difference of $\approx$1000 K with respect to the photosphere of 4660 K and is likely surrounded by a moat-like velocity field. Three more weaker spots add to the total surface spottedness, which is up to 25% of the visible surface. Seven optical chromospheric tracers show rotational modulation of their emission line fluxes in phase with the cool spots. This surface configuration appears to have been stable for the 522 days of our observations.

The issue of over-predicting the galaxy-galaxy lensing (GGL) signal using conventional galaxy-halo connection models has become well-known as the ``Lensing is Low'' problem, which has been extensively investigated using the Baryon Oscillation Spectroscopic Survey (BOSS) galaxy samples. This issue is also tightly related to the so-called $S_8$ tension. By applying our Photometric objects Around Cosmic webs (PAC) method to the BOSS survey and the DESI deep photometric survey, we obtained hundreds of cross-correlation measurements to establish an accurate galaxy-halo connection for BOSS galaxies through the halo abundance matching technique (Paper IV). With this galaxy-halo connection, we show in this work that the predicted GGL signals for BOSS galaxies both in the Planck and WMAP Universes actually agree very well with the GGL measurements. We find the best-fitting value $S_8 = 0.8294 \pm 0.0110$, $0.8073 \pm 0.0372$ and $0.8189 \pm 0.0440$ for the CMASS samples with the source galaxies from HSC, DES and KiDS image surveys, respectively. Our work indicates that accurate modeling of the lens population is so critical to interpret the GGL observation. For the scale of $r_p < 0.6\,h^{-1}\rm{Mpc}$, our GGL prediction for LOWZ samples are also in good agreement with the observations of HSC and DES. However, the GGL observation of KiDS is much lower on the small scale. Our results indicate that no significant baryon feedback is needed to suppress the small scale clustering unless the the GGL observation of KiDS on the small scale will be confirmed.

High-mass prestellar cores are extremely rare. The search for such objects has long been hindered by small sample sizes, leading to large uncertainties in their lifetimes and the conditions in which high-mass stars ($> 8\,M_{\odot}$) form. We leverage the large sample ($\sim 580$ cores) detected in the ALMA-IMF survey to identify both protostellar and prestellar cores and estimate their relative lifetimes. We use CO and SiO outflows to identify protostellar cores and introduce a new automated method based on aperture line emission and background subtraction to systematically detect outflows associated with each of the 141 most massive cores. Massive cores that do not drive an outflow in either tracer are classified as prestellar. Our method enables efficient outflow detection with performance comparable to more traditional techniques. We identify 30 likely prestellar cores with $M > 8\,M_{\odot}$, including 12 with $M > 16\,M_{\odot}$, the best candidates for high-mass star precursors. Most of these 12 cores reside in the crowded central regions of protoclusters, where high-mass stars are expected to form. Using prestellar-to-protostellar core ratios and a 300 kyr protostellar lifetime, we estimate prestellar lifetimes of 120 to 240 kyr for $8\,M_{\odot} < M < 16\,M_{\odot}$ and 50 to 100 kyr for $30\,M_{\odot} < M < 55\,M_{\odot}$. These timescales, which depend on different mass reservoir evolution scenarios, significantly exceed the 4 to 15 kyr free-fall time of the cores, suggesting that high-mass cores persist for 10 to 30 free-fall times. This indicates that collapse is slowed by turbulence, magnetic fields, or rotation at or below the observed scale.

S-shaped radio galaxy jets are prime sources for investigating the dynamic interplay between the central active galactic nucleus, the jets, and the ambient intergalactic medium. These sources are excellent candidates for studying jet precession, as their S-shaped inversion symmetry strongly indicates underlying precession. We present a multiwavelength analysis of the giant inversion-symmetric S-shaped radio galaxy PKS 2300-18, which spans 0.76 Mpc. The host is a quasar at a redshift of 0.128, displaying disturbed optical morphology due to an ongoing merger with a companion galaxy. We conducted a broadband radio spectral study using multifrequency data ranging from 183 MHz to 6 GHz, incorporating dedicated observations with the uGMRT and JVLA alongside archival radio data. A particle injection model was fitted to the spectra of different regions of the source to perform ageing analysis, which was supplemented with a kinematic jet precession model. The ageing analysis revealed a maximum plasma age of ~ 40 Myr, while the jet precession model indicated a precession period of ~ 12 Myr. ROSAT data revealed an X-ray halo of Mpc size, and from Chandra the AGN X-ray spectrum was modelled using thermal and power-law components. The optical spectrum displaying double-peaked broad emission lines was modelled, indicating complex broad-line region kinematics at the centre with the possibility of a binary SMBH. We present the results of our multiwavelength analysis of the source, spanning scales from a few light-days to a few Mpc, and discuss its potential evolutionary path.

We derive all the orbital parameters of the blue large-amplitude pulsator (BLAP) in the binary system HD133729 by exploiting the frequency modulation (FM) method, which is based on the analytical relations between the orbital parameters and a multiplet separated by the orbital frequency in the frequency spectrum of the light curve. Because the FM method uses the entire data through the Fourier transform, it is the most effective use of high-precision photometry data, taken over a long timespan by the TESS space mission, for determining orbital parameters.

NASA's Parker Solar Probe and ESA/NASA's Solar Orbiter are encounter missions that are currently both in their nominal science phases, venturing closer to the Sun than ever before. These complementary spacecraft are operating together in order to combine in situ measurements of solar wind plasma in the inner heliosphere with high-resolution remote sensing observations of their source regions in the solar atmosphere. This paper highlights the synergetic science that these multi-viewpoint messengers of the inner heliosphere enable and how they are working together to significantly advance our understanding of the physical processes that are important for solar wind formation, the eruption of coronal mass ejections and their space weather effects.

The intrinsic alignment of galaxies is a major astrophysical contaminant to weak gravitational lensing measurements, and the study of its dependence on galaxy properties helps provide meaningful physical priors that aid cosmological analyses. This work studies for the first time the dependence of intrinsic alignments on galaxy structural parameters. We measure the intrinsic alignments of bright galaxies, selected on $r$-band magnitude $r<20$, in the Kilo-Degree Survey. Machine-learning-based photometric redshift estimates are available for this galaxy sample that help obtain a clean measurement of its intrinsic alignment signal. We supplement this sample with a catalogue of structural parameters from Sérsic profile fits to the surface brightness profiles of the galaxies. We split the sample in galaxy intrinsic colour, luminosity and Sérsic index, and we fit the non-linear linear alignment model to galaxy position - shape projected correlation function measurements at large scales. We observe a power-law luminosity dependence of the large-scale intrinsic alignment amplitude, $A_\mathrm{IA}$, for both the red and high Sérsic index ($n_s>2.5$) samples, and find no significant difference between the two samples. We measure a $\sim1.5\sigma$ lower $A_\mathrm{IA}$ for red galaxies that also have a Sérsic index $n_s<4$, compared to the expected amplitude predicted using sample's luminosity. We also probe the intrinsic alignment of red galaxies as a function of galaxy scale by varying the radial weight employed in the shape measurement. We find no significant difference on large scales but on small scales, alignments increase with galaxy scale. For intrinsically blue galaxies, we find $A_\mathrm{IA}=-0.67\pm1.00$, consistent with previous works. We also find alignments to be consistent with zero for the low Sérsic index ($n_s<2.5$) sample.

Diffuse radio sources, known as mini-halos and halos, are detected at the centres of galaxy clusters. These centralized diffuse sources are typically observed individually, with both appearing together only in rare cases. The origin of the diffuse radio sources in such systems remains unclear. We investigate the formation of large-scale radio emission in the most X-ray luminous, massive galaxy cluster RXJ~1347.5-1145 which is known to host a mini-halo at its centre and possibly additional more extended emission. We conduct deep multi-frequency observations of the galaxy cluster using the MeerKAT at 1.28 GHz and the uGMRT (upgraded Giant Metrewave Radio Telescope) at 1.26 GHz and 700 MHz. We characterize the brightness and spectral properties of the central diffuse sources and combine our radio observations with \textit{Chandra} X-ray data to explore the correlation between the cluster's non-thermal and thermal emissions. We confirm the presence of the diffuse emission and find that it extends up to 1~Mpc in size. Our multi-wavelength data reveal that the central diffuse emission consists of two distinct components: a mini-halo located in the cluster core and a larger radio halo extending around it. The correlation between radio and X-ray surface brightness in both sources indicates a strong connection between the non-thermal and thermal properties of the ICM. The differing slopes in the $I_R-I_X$ and $\alpha-I_X$ relations suggest that distinct mechanisms are responsible for the formation of the mini-halo and halo. The properties of the halo align with the turbulent model, while both turbulent and hadronic processes may contribute to the formation of the mini-halo.

In this paper we reanalyze the extended ETV curves of the formerly identified triple star candidates and many other $Kepler$ EBs. Besides the confirmations of the former findings and/or the improvements of the triple systems' orbital properties, the extended time-base allows us to identify several new, longer outer period triple systems, and it also makes possible a more detailed study of the dynamical perturbations in the tightest triple stars. We extend the ETV curves of the $Kepler$ triples with those mid-eclipse times which can be deduced from the TESS observations and, moreover, from targeted ground-based follow up observations for a number of the objects. In general, we use the same methods that were applied for the older studies, which are described in the literature. Due to the lower quality of the TESS observations, however, for the fainter systems we average light curves of the EBs for 5-20 consecutive cycles, and thereby calculate `normal' minima from these averaged light curves. In conclusion, we identified 243 hierarchical triple star candidates in the $Kepler$ sample. This sample strongly overlaps our former, nine-year-old sample, confirming the older results, or providing new solutions for 193 systems of the 2016 sample. For the remaining 28 hierarchical triple candidates of that former study, we were unable to find new solutions either because of the disappearance of the eclipses due to orbital plane precession, or due to instrumental reasons. On the other hand, due to the extended time series, we were able to identify 50 new, longer period triple star candidates, as well. We briefly discuss the main properties of each individual system and present statistical studies of the results, as well.

Calculating the action and the interaction Hamiltonian at higher orders in cosmological perturbation theory is a cumbersome task. We employ the formalism of EFT of inflation in models of single field ultra slow-roll inflation and obtain a non-perturbative result for the Hamiltonian in terms of the Goldstone field $\pi$. To complete the dictionary, a non-linear relation between the curvature perturbations and $\pi$ is presented. Equipped with these non-linear results, we calculate the higher order loop corrections in USR models which are employed for PBHs formation. It is shown that the loop corrections on long CMB scales increase rapidly with the number of loop $L$ and the setup will go out of perturbative control at the four-loop level.

Luminous blue variables are an intermediate stage in the evolution of high-mass stars characterized by extreme mass loss and substantial variability. The stars show large irregular episodic variations on timescales of years to decades in these stars' effective temperatures (called "S Dor variations"). Observations show that these variations are triggered when the stars are in a well-defined strip in the HRD that corresponds to the Modified Eddington Limit, where the atmospheric radiation pressure almost balances gravity. In this work we consider the role that rotation plays in the instability that leads to the triggering of S Dor variations in luminous post-main sequence LBVs. We adopt the existing instability criterion that the effective surface gravity is reduced to 10% of the Newtonian gravity due to radiation pressure in the atmosphere of non-rotating stars. We then specifically describe how rotation impacts this instability. By carrying out numerical simulations of model LBVs at both solar and sub-solar metallicities, we confirm that most LBVs should be unstable at both the equator and the poles, and that rotation exacerbates this effect; some models also produce enhanced mass loss at the pole or equator. Our numerical models also predict dense equatorial disks or rings and high-velocity bipolar outflows, in agreement with existing observations of LBV circumstellar nebulae.

In a poster presentation for IAU Symposium 392: "Neutral hydrogen in and around galaxies in the SKA era", we gave an overview of the HI-MaNGA project which is working to obtain complementary information about the cold gas (neutral hydrogen traced by the radio 21cm line) content of Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) sample galaxies. MaNGA, part of the fourth incarnation of the Sloan Digital Sky Surveys (SDSS-IV), obtained spatially resolved spectral maps for 10,000 nearby galaxies selected to create a representative sample out of the SDSS Main Galaxy Sample. MaNGA data have provided a census of the stellar and ionized gas content of these galaxies, as well as kinematics of both stars and gas. Adding HI information via the HI-MaNGA program, which has observed or collected 21cm line data for 70% of the full MaNGA sample, has been crucial for a number of applications, but especially understanding the physical mechanisms that regulate gas accretion, and through that star formation and quenching of star formation. This conference proceedings article accompanies the release of the DR3 version of HI-MaNGA data.

Using data collected by the Indian Mars Orbiter Mission in October 2021, we investigated coronal regions of the Sun by analyzing the Doppler spectral width of radio signals to estimate solar wind velocity. A simplified equation is introduced to directly relate these two parameters. The study focuses on observations conducted from October 2 to October 14, 2021, a relatively quiet phase of solar cycle 25. The analysis targeted the coronal region within heliocentric distances of 5-8 RSun, near the ecliptic plane. In this region, solar wind velocities ranged from 100 to 150 kms^-1, while electron densities were on the order of 10^10 m^(-3). We also compared our results with electron density observations and models derived from previous studies. Though the decrease in the electron densities with respect to increasing helio-centric distance matches quite well with the theoretical models, MOM estimates fall at the lower edge of the distribution. This difference may be attributed to the prolonged weak solar activity during the MOM observations, in contrast to prior studies conducted during periods of comparatively higher solar activity in earlier solar cycles.

Many large scale structure surveys sort their observations into redshift bins and treat every tracer as being located at the mean redshift of its bin, a treatment which we refer to as the equal time approximation. Recently, a new method was developed which allows for the estimation and correction of errors introduced by this approximation, which we refer to as the unequal time correlator-level projection. For single tracer power spectra, corrections arise at second order and above in a series expansion, with first order terms surviving only in multi-tracer analyses. In this paper we develop a new method which we refer to as the unequal time field level projection. This formalism projects the fields individually onto the celestial sphere, displaced from individual reference times, before defining their correlators. This method introduces new, first order correction terms even in the case of single tracer power spectra. Specifically, new first order terms are introduced which apply to both cross-bin and single bin correlators. All of these new corrections originate with derivatives over combinations of a delta function, a cross-bin phase term, and the power spectrum itself and stem from the introduction of two unequal time Fourier transforms into the analysis. We analyse these corrections in the context of a linearly biased power spectrum divided between two redshift bins and find that they can lead to non-trivial corrections, particularly to cross-bin correlators. We also show that these terms can be replicated by appropriately extending the correlator-level analysis to include a second Fourier transform which allows for a full redshift bin integration.

A previously faint young stellar object (YSO), V557 Mon, rapidly brightened in late 2024 and is currently at least $\Delta G=3.3$ magnitudes brighter than its typical pre-outburst brightness. The ongoing outburst is identified in the Gaia Alerts system as Gaia24djk. We obtained a 1-2.5 $\mu$m spectrum of the object and find the spectrum is dominated by line emission and continuum excess consistent with rapid YSO accretion, similar to the star EX Lup during its outburst state. We speculate that the burst, which has not yet reached its peak brightness, may become an FU Ori outburst, which would be evidenced by the emission spectrum turning into an absorption spectrum.

We identify an axis connecting two opposite `ears' in the supernova remnant W49B and morphological signatures of three arcs around this axis that we claim are sections of full circum-jet rings. Based on recent identifications of morphological signatures of jets in core-collapse supernovae (CCSNe), including ejecta-rich axes, we reexamine images of W49B and identify a heavy element-rich protrusion (ear) as a jet-inflated structure. We identify the opposite ear and a clump at its tip as the signature of the opposite jets. The line connecting the two clumps at the tips of the two opposite ears forms the main jet axis of W49B. We compare the three arcs around the main jet axis in W49B to the circum-jet rings of the jets in the Cygnus A galaxy and deduce that these arcs are sections of full circum-jet rings in W49B. In W49B, the jets are long gone, as in some planetary nebulae with circum-jet rings. Identifying the main jet axis is incompatible with a type Ia supernova. It leaves two possibilities: that jets exploded W49B as a CCSN, i.e., the jittering jets explosion mechanism where the pair of jets we identify is one of many that exploded the star, or that the explosion was a common envelope jet supernova with a thermonuclear outburst, i.e., both the pair of jets and thermonuclear outburst exploded the core of a red supergiant star as a pre-existing neutron star tidally destroyed it.

A neutrino-like event with an energy of $\sim 220 \,{\rm PeV}$ was recently detected by the KM3NeT/ARCA telescope. If this neutrino comes from an astrophysical source, or from the interaction of an ultra-high-energy cosmic ray in the intergalactic medium, the ultra-high-energy gamma rays that are co-produced with the neutrinos will scatter with the extragalactic background light, producing an electromagnetic cascade and resulting in emission at GeV-to-TeV energies. In this paper, we compute the gamma-ray flux from this neutrino source considering various source distances and strengths of the intergalactic magnetic field (IGMF). We find that the associated gamma-ray emission could be observed by existing imaging air cherenkov telescopes and air shower gamma-ray observatories, unless the strength of the IGMF is $B\gtrsim 3\times 10^{-13}$ G, or the ultra-high-energy gamma-rays are attenuated inside of the source itself. In the latter case, this source is expected to be radio-loud.

We compare three methods of deriving the local Galactic star formation history, using as a benchmark the Gaia-defined 40 pc white dwarf sample, currently the largest volume complete sample of stellar remnants with medium-resolution spectroscopy. We create a population synthesis model to 1) reproduce the observed white dwarf luminosity function, 2) reproduce the observed absolute Gaia G magnitude distribution, and 3) directly calculate the ages of all individual white dwarfs in the 40 pc volume. We then compare the star formation histories determined from each method. Previous studies using these methods were based on different white dwarf samples and as such were difficult to compare. Uncertainties in each method such as the initial mass function, initial-final mass relation, main sequence lifetimes, stellar metallicity, white dwarf cooling ages and binary evolution are accounted for to estimate the precision and accuracy of each method. We conclude that no method is quantitatively better at determining the star formation history and all three produce star formation histories that agree within uncertainties of current external astrophysical relations.

A meta-analysis of seismic ages determined for individual stars in the well-studied open and globular clusters NGC 6819, NGC 6791, M67, M4, M19, M80, and M9 reveals both high variance across measurements and significant discrepancy with independent, isochrone-based age determinations for the clusters in which these stars reside. The scatter among asteroseismic ages for individual stars in any one of these clusters far surpasses both the absolute age uncertainty computed for reference cluster M92 (5.4\%) and the model-to-model systematic uncertainties in isochrones (roughly 10\%). This suggests that either binary processes are significantly altering the masses of stars in these clusters, or some additional corrections, perhaps as a function of mass, metallicity, or surface gravity, are required to bring the asteroseismic age scale into concordance with ages inferred from isochrone or similar model fitting.

Galactic double white dwarfs will be prominent gravitational-wave sources for the Laser Interferometer Space Antenna (LISA). While previous studies have primarily focused on formation scenarios in which binaries form and evolve in isolation, we present the first detailed study of the role of triple stellar evolution in forming the population of LISA double white dwarfs. In this work, we present the first detailed study of the role of triple stellar evolution in forming the population of LISA double white dwarfs. We use the multiple stellar evolution code (MSE) to model the stellar evolution, binary interactions, and the dynamics of triple star systems then use a Milky Way-like galaxy from the TNG50 simulations to construct a representative sample of LISA double white dwarfs. In our simulations about $7\times10^6$ Galactic double white dwarfs in the LISA frequency bandwidth originate from triple systems, whereas $\sim4\times10^6$ form from isolated binary stars. The properties of double white dwarfs formed in triples closely resemble those formed from isolated binaries, but we also find a small number of systems $\sim\mathcal{O}(10)$ that reach extreme eccentricities $(>0.9)$, a feature unique to the dynamical formation channels. Our population produces $\approx 10^{4} $ individually resolved double white dwarfs (from triple and binary channels) and an unresolved stochastic foreground below the level of the LISA instrumental noise. About $57\,\%$ of double white dwarfs from triple systems retain a bound third star when entering the LISA frequency bandwidth. However, we expect the tertiary stars to be too distant to have a detectable imprint in the gravitational-wave signal of the inner binary.

The morphological classification of galaxies provides vital physical information about the orbital motions of stars in galaxies, and correlates in interesting ways with star formation history, and other physical properties. Galaxy morphological classification is a field with a history of more than 100 years of development, and many scientists have introduced new classification schemes, resulting in a sometimes confusing array of terminologies and overlapping classes. In this article I provide a brief historical review of galaxy classification, but focus mostly on providing a summary of how the morphological variety of galaxies seen in our expanding Universe are described. I review traditional visual classification, morphometric measurements, crowd-sourcing for large scale visual classifications (Galaxy Zoo), and of course the recent explosion of interest in making use of machine learning techniques for galaxy morphology classification. A look up table is provided for cross matching of various terminologies currently in use for galaxy morphology classification as well as brief definitions of the main morphological types.

A global scale-invariant Dark Energy model based on Induced Gravity with the addition of a small $R^2$ contribution is examined. The scalar field (quintessence), playing the role of Dark Energy, has a quartic potential and generates Newton's constant with its non-minimal coupling (after introducing a suitable symmetry breaking). Even when small, the $R^2$ contribution significantly modifies the cosmological evolution of the matter-gravity system. The solutions to this model are obtained analytically through a perturbative expansion and oscillate with transplanckian frequency. They are then compared with similar solutions found for $\Lambda$CDM cosmology plus $R^2$. Finally scalar field production is perturbatively taken into account in a simple model and the resulting effects illustrated.

The first exact and analytical solution representing an equilibrium configuration of two stationary black holes, in general relativity, is presented. The metric models two collinear extremal Kerr black holes immersed into an external and back-reacting rotating tidal drag. The gravitational attraction is balanced by the repulsive gravitational spin-spin interaction generated by the interplay between black holes angular momenta with the rotational background. The new solution is built by embedding the double Kerr metric into a swirling universe by means of the Ehlers transformation. The geometry is completely regular outside the event horizons. Thermodynamic properties of the binary black hole system are studied, the Smarr law, the first law and the Christodoulou-Ruffini formulas are verified. Microscopic degrees of freedom of the entropy are computed from the dual CFT living on the boundary of the near horizon geometries.

Ultralight bosonic (ULB) fields with mass $m_{\phi} \ll 1$ eV often arise in theories beyond the Standard Model (SM). If such fields exist, violent astrophysical events that result in emission of gravitational wave, photon, or neutrino signals could also produce bursts of high-density relativistic ULB fields. Detection of such ULB fields in terrestrial or space-based laboratories correlated with other signals from transient astrophysical events opens a novel avenue for multimessenger astronomy. We show that quantum sensors are particularly well-suited to observe emitted scalar and pseudoscalar axion-like ULB fields coupled to SM. We demonstrate that multimessenger astronomy with ULB fields is possible even when accounting for matter screening effects.

Conversions between the states in the dark sector affect not only their number densities but also their momentum distributions. In this work we study a phenomenologically motivated two-component dark matter scenario, based on the Coy Dark Matter model, in order to quantify the effect of conversions on departure from kinetic equilibrium and consequently the relic abundance. We perform a detailed numerical analysis at the level of the phase space distributions of dark sector particles, implementing all the relevant processes, including conversions, elastic scatterings and annihilations. Focusing on the parameter regions that lead to the observed relic abundance and provide a good fit to the Galactic Centre excess, we find that departure from kinetic equilibrium can alter the predictions for the total abundance by more than $100\%$, while in most of the interesting parameter space being in the range from around $-20\%$ to $50\%$. The effect on each dark matter constituent separately can be much larger, even up to an order of magnitude, which can significantly affect the expected present-day gamma ray flux, and consequently phenomenology of the model.

The standard formula, due to Spiegel, for the smoothing of temperature fluctuations by radiative transfer is unstable in relativity. This is due to the fact that Spiegel neglected the transit time of light, thereby allowing the transport coefficients to move outside the convex geometry compatible with causality (the "hydrohedron"). Here, we fix this pathology. First, we prove that the linearized radiative transfer equations are causal and covariantly stable by construction. Then, we repeat Spiegel's calculation accounting for the finite speed of photons. We find that the full transfer problem can be solved analytically. All the infinite (exact) transport coefficients arising from it fall inside the hydrohedron. Our analysis also accounts for isotropic scattering.

We propose a mechanism of symmetry breaking or restoration that can occur in the middle of inflation due to the coupling of the Gauss-Bonnet term to a charged scalar. The Gauss-Bonnet coupling results in an inflaton-dependent effective squared mass of the charged scalar, which can change its sign (around the symmetric point) during inflation. This can lead to spontaneous breaking of the symmetry, or to its restoration, if it is initially broken. We show the conditions under which the backreaction of the Gauss-Bonnet coupling on the inflationary background is negligible, such that the predictions of a given inflationary model are unaffected by the symmetry breaking/restoration process.

The interaction between Jupiter's magnetosphere and the solar wind is not well-constrained: while internal energetic plasma processes are thought to dominate plasma circulation, the solar wind nonetheless exerts significant control over the shape and scale of the whole structure. To better constrain this interaction, we derive new functional forms for Jupiter's magnetopause and bow shock using data from the $Ulysses$, $Galileo$, $Cassini$, and $Juno$ missions and calibrated solar wind estimates from the Multi-Model Ensemble System for the Heliosphere (MMESH). We design an empirical Bayesian model to estimate the locations of the boundaries using a Markov-chain Monte Carlo (MCMC) algorithm, expanding our model to sample all times, not only boundary crossing events. The boundary surfaces which best describe the data are thus estimated without the need for a full, physics-based magnetohydrodynamic (MHD) treatment of the Jovian magnetosphere and the additional assumptions required for such. The new magnetopause model exhibits significant polar flattening and dawn-dusk asymmetry, and includes a narrowing of the magnetotail when compared to previous models. The new bow shock model is largely axisymmetric. Both boundary models describe surfaces which lie closer to Jupiter than previous models, which has important implications for the modern picture of Jupiter's dynamic magnetosphere and the expected science results of current and upcoming Jupiter-bound spacecraft. Applying these models to $Juno$'s trajectory, we estimate that the spacecraft should be expected to spend ${\sim}19\%$ of each orbit in the magnetosheath and ${\sim}4\%$ of each orbit in the solar wind starting from Perijove 64 (PJ64, 21 July 2021).

Quantum kinetics of neutrinos are known to potentially change the classical neutrino radiation field in high-energy astrophysical sources such as core-collapse supernovae and binary neutron-star mergers. However, the mixing phenomena still have open issues in the nonlinear dynamics and the asymptotic states, particularly for recently discovered collision-induced flavor conversion. In this paper, we investigate linear and nonlinear dynamics of collisional neutrino-flavor conversion (CFC) with multi-energy neutrino gases through numerical simulations, demonstrating that the asymptotic states dramatically change depending on unstable modes dominating the system. In one unstable mode, high-energy neutrinos reach a flavor equipartition, but low-energy neutrinos return back to almost their initial states. In contrast, in the other one, rather low-energy neutrinos achieve a full flavor swap, but high-energy neutrinos undergo less flavor conversion. We clarify the distinct spectral behaviors in two different ways based on stability analysis and flavor pendulum. Our result suggests that CFC with flavor swap can become crucial at deeper radii with low electron fraction and requires more detailed theoretical modeling of neutrino quantum kinetics.

We discuss the constraints on superluminal neutrino Lorentz Invariance Violation (LIV) parameters from the observation of the ultra-high-energy event KM3-230213A by KM3NeT collaboration in cases of linear $n=1$ and quadratic $n=2$ LIV scenarios. Assuming extragalactic origin of the event, we obtain the constraints on LIV mass scale $\Lambda_{n=1} = 5.4 \times 10^{30}\, \mbox{GeV}$ and $\Lambda_{n=2} = 3.5 \times 10^{19}\, \mbox{GeV}$ from the absence of neutrino splitting.