Papers for Friday, Feb 07 2025

Recent discoveries of apparent large-scale features in the structure of the universe, extending over many hundreds of megaparsecs, have been claimed to contradict the large-scale isotropy and homogeneity foundational to the standard ($\Lambda$CDM) cosmological model. We explicitly test and refute this conjecture using FLAMINGO-10K, a new and very large cosmological simulation of the growth of structure in a $\Lambda$CDM context. Applying the same methods used in the observations, we show that patterns like the "Giant Arc", supposedly in tension with the standard model, are, in fact, common and expected in a $\Lambda$CDM universe. We also show that their reported significant overdensities are an algorithmic artefact and unlikely to reflect any underlying structure.

We use JWST Near-Infrared Spectrograph (NIRSpec) observations from the the Cosmic Evolution Early Release survey (CEERS), GLASS-JWST ERS (GLASS), and JWST Advanced Deep Extragalactic Survey (JADES) to measure rest-frame optical emission-line ratios of 90 galaxies at z>4. The stacked spectra of galaxies with and without a broad-line feature reveal a difference in the [OIII]$\lambda$ 4363 and H$\gamma$ ratios. This motivated our investigation of the [OIII]/H$\gamma$ vs [NeIII]/[OII] diagram. We define two AGN/SF classification lines based on 1869 SDSS galaxies at z$\sim$0. After applying a redshift correction to the AGN/SF lines we find 76.8% of BLAGN continue to land in the AGN region of the diagnostic largely due to the [NeIII]/[OII] ratio. However, 40.2% of non-BLAGN land in the AGN region as well, this could be due to star forming galaxies having harder ionization of there are narrow line AGN which are not accounted for. This indicates the potential of the [NeIII]/[OII] ratio to continue classifying galaxies to z$\sim$6. We further inspect galaxies without broad emission lines in each region of [OIII]/H\gamma vs [NeIII]/[OII] diagram and found that they have slightly stronger CIII]$\lambda$1908 fluxes and equivalent width when landing in the BLAGN region. However, the cause of this higher ionization is unclear. Additionally, we find that BLAGN are characterized by a higher ionization (at constant electron temperature) compared to non-broad line galaxies.

The phase space of stellar streams is proposed to detect dark substructure in the Milky Way through the perturbations created by passing subhalos - and thus is a powerful test of the cold dark matter paradigm and its alternatives. Using graph convolutional neural network (GCNN) data compression and simulation-based inference (SBI) on a simulated GD-1-like stream, we improve the constraint on the mass of a [$10^8$, $10^7$, $10^6$] $M_\odot$ perturbing subhalo by factors of [11, 7, 3] with respect to the current state-of-the-art density power spectrum analysis. We find that the GCNN produces posteriors that are more accurate (better calibrated) than the power spectrum. We simulate the positions and velocities of stars in a GD-1-like stream and perturb the stream with subhalos of varying mass and velocity. Leveraging the feature encoding of the GCNN to compress the input phase space data, we then use SBI to estimate the joint posterior of the subhalo mass and velocity. We investigate how our results scale with the size of the GCNN, the coordinate system of the input and the effect of incomplete observations. Our results suggest that a survey with $10 \times$ fewer stars (300 stars) with complete 6-D phase space data performs about as well as a deeper survey (3000 stars) with only 3-D data (photometry, spectroscopy). The stronger constraining power and more accurate posterior estimation motivate further development of GCNNs in combining future photometric, spectroscopic and astrometric stream observations.

The simulation of gravitational wave source populations and their progenitors is an endeavor more than eighty years in the making. This is in part due to a wide variety of theoretical uncertainties that must be taken into account when describing how stellar populations evolve over cosmic time to produce double stellar remnant binaries. Population synthesis software has been developed as a means to investigate these uncertainties under a wide variety of physical assumptions and stellar population formation environments. In this chapter we discuss the development history of population synthesis software with a special focus on work aimed at understanding the formation of gravitational wave populations. We detail the assortment of population synthesis tools in use today that simulate GW populations which are born and evolve in different astrophysical environments. We further discuss the GW population rates and features associated with each environment that have been predicted for both ground and space-based GW detectors. We finish with considerations of future work that combines possible constraints from electromagnetic surveys that may provide key findings that break current degeneracies in population synthesis predictions of GW source populations.

The absence of direct high redshift observations poses a significant challenge in understanding the properties of first stars. Nonetheless, the cumulative effect of entire stellar populations can be studied with current data. In this work we use a combination of high redshift observables in order to infer the formation and emission properties of the first stellar populations: high redshift UVLFs, the optical depth of CMB photons to reionization, hydrogen absorption lines in quasar spectra, and measurements of the soft cosmic X-ray background. We study two minimal models of stellar population: i) a single, Pop-II, stellar population which dominates throughout Cosmic Dawn, ii) two distinct stellar populations, Pop-II and Pop-III, dominating at different times with the transition between them taken as a free parameter. We set strong constraints on the properties of Pop-II stars, and upper limits on the formation and multi-wavelength emission of Pop-III stars. After applying the constraints above, we present the viable envelopes of the 21-cm global signal with and without Pop-III stars. We identify a region in the parameter space of the two population model which predicts a global 21-cm signal distinctive from that of the single population one. A measurement of such a signal would be a strong indication for the presence of Pop-III stars at early times.

Astrometry from Gaia has enabled discovery of three dormant black holes (BHs) in au-scale binaries. Numerous models have been proposed to explain their formation, including several that have forecasted Gaia detections. However, previous works have used simplified detectability metrics that do not capture key elements of the Gaia astrometric orbit selection function. We apply a realistic forward-model of Gaia astrometric orbit catalogs to BH binary populations generated through (a) isolated binary evolution (IBE) and (b) dynamical formation in star clusters. For both formation channels, we analyze binary populations in a simulated Milky Way-like galaxy with a realistic metallicity-dependent star formation history and 3D dust map. We generate epoch astrometry for each binary from the Gaia scanning law and fit it with the cascade of astrometric models used in Gaia DR3. The IBE model of Chawla et al. (2022) predicts that no BH binaries should have been detected in DR3 and thus significantly underpredicts the formation rate of Gaia BHs. In contrast, the dynamical model of Di Carlo et al. (2024) overpredicts the number of BHs receiving DR3 orbital solutions by a factor of $\sim$8. The two models predict very different orbital period distributions, with the IBE model predicting only binaries that avoided common envelope evolution and have $P_{\text{orb}} \gtrsim 2,000$ d to be detectable, and the dynamical formation model predicting a period distribution that is roughly log-uniform. Adopting the dynamical channel as a fiducial model and rescaling by a factor of 1/8 to match DR3, we predict that $\sim$30 BH binaries will be detected in Gaia DR4, representing $\sim0.1\%$ of Milky Way BHs with luminous companions in au-scale orbits.

Interpreting galactic luminosity requires assumptions about the galaxy-wide initial mass function (gwIMF), often assumed invariant in most stellar population synthesis (SPS) models. If stars form in clusters with metallicity- and density-dependent \textit{stellar IMFs}, the integrated galaxy-wide IMF (IGIMF) can be calculated, with its shape depending on the star formation rate (SFR) and metallicity. The shape of the IGIMF thus depends on the star formation rate (SFR) and metallicity. We develop the \texttt{SPS-VarIMF} code which enables us for the first time to compute the spectra, luminosities, and remnant populations of galaxies in the context of the varying gwIMF with time, SFR, and an assumed metallicity. Using the \texttt{SPS-VarIMF} code one can calculate how the interpretation from the integrated galactic light may change if the underlying galaxy-wide IMF is assumed to be environmentally dependent instead of being invariant. In particular, we compare the time evolution of the galaxy color and the stellar mass-to-light ratio in different bands for the IGIMF and invariant canonical gwIMF assuming constant and delayed-$\tau$ star formation histories. We show that the underlying gwIMF can be determined by examining the colors and luminosities of late-type galaxies in UV and optical bands. On the other hand, for early-type galaxies, it is difficult to distinguish which gwIMF is valid since adopting the different gwIMFs yields almost identical colors. However, their gwIMF-dependent $M/L$ ratios differ by up to an order of magnitude. Massive present-day elliptical galaxies would have been $10^4$ times as bright as at present when they were forming.

Gravitational lensing galaxies are commonly modeled with elliptical density profiles, to which angular complexity is sometimes added through a multipole expansion - encoding deformations of the elliptical iso-density contours. The formalism that is widely used in current studies and software packages, however, employs perturbations that are defined with respect to a circle. In this work, we show that this popular formulation (the "circular multipoles") leads to perturbation patterns that depend on the axis ratio and do not agree with physical expectations (from studies of galaxy isophotal shapes) when applied to profiles that are not near-circular. We propose a more appropriate formulation, the "elliptical multipoles", representing deviations from ellipticity suited for any axis ratio. We solve for the lensing potentials associated with the $m=1$ circular multipole (previously undetermined in the isothermal case), as well as the elliptical multipoles of any order $m$, assuming a near-isothermal reference profile. We implement these solutions into the lens modeling package $\mathtt{lenstronomy}$, and assess the importance of the multipole formulation by comparing flux-ratio perturbations in mock lensed systems with quadruply imaged quasars: we show that elliptical multipoles typically produce smaller flux-ratio perturbations than their circular counterparts.

Leveraging the wide area coverage of the COSMOS-Web survey, we quantify the abundance of different morphological types from $z\sim 7$ with unprecedented statistics and establish robust constraints on the epoch of emergence of the Hubble sequence. We measure the global (spheroids, disk-dominated, bulge-dominated, peculiar) and resolved (stellar bars) morphologies for about 400,000 galaxies down to F150W=27 using deep learning, representing a two-orders-of-magnitude increase over previous studies. We then provide reference Stellar Mass Functions (SMFs) of different morphologies between $z\sim 0.2$ and $z\sim 7$ and best-fit parameters to inform models of galaxy formation. All catalogs and data are made publicly available. (a)At redshift z > 4.5, the massive galaxy population ($\log M_*/M_\odot>10$) is dominated by disturbed morphologies (~70%) -- even in the optical rest frame -- and very compact objects (~30%) with effective radii smaller than ~500pc. This confirms that a significant fraction of the star formation at cosmic dawn occurs in very dense regions, although the stellar mass for these systems could be overestimated.(b)Galaxies with Hubble-type morphologies -- including bulge and disk-dominated galaxies -- arose rapidly around $z\sim 4$ and dominate the morphological diversity of massive galaxies as early as $z\sim 3$. (c)Using stellar bars as a proxy, we speculate that stellar disks in massive galaxies might have been common (>50%) among the star-forming population since cosmic noon ($z\sim2$-2.5) and formed as early as $z\sim 7$ (d)Massive quenched galaxies are predominantly bulge-dominated from z~4 onward, suggesting that morphological transformations briefly precede or are simultaneous to quenching mechanisms at the high-mass end. (e) Low-mass ($\log M_*/M_\odot<10$) quenched galaxies are typically disk-dominated, pointing to different quenching routes in the two ends of the stellar mass spectrum from cosmic dawn.

General relativistic magnetohydrodynamic (GRMHD) simulations have been instrumental in our understanding of high energy astrophysical phenomena over the past two decades. Their robustness and modularity make them a great tool for understanding the dynamics of various astrophysical objects. In this paper we have used GRMHD simulations to understand the accretion flows of ultraluminous X-ray sources (ULXs) and blazars. ULXs are enigmatic sources which exhibit very high luminosities (super-Eddington for stellar mass black holes) even in their low-hard state. Numerical steady state calculations have shown that this behaviour can be explained by considering ULXs to be highly magnetised advective accretion sources around stellar-mass black holes. Our simulation confirms that such an accretion flow can indeed produce the high luminosities observed in ULXs. Further to continue towards the supermassive black holes, we have also modeled blazars and have used our simulation results to explain the apparent dichotomy in the two blazar classes: flat spectrum radio quasars (FSRQs) and BL Lacertae (BL Lacs). Our results show that FSRQ and BL Lacs show different spectral characteristics due to a difference in their magnetic field characteristics. The different categories of FSRQs and BL Lacs have also been explained by the interplay between the spin, magnetic field and accretion rate of the central supermassive black hole.

Strongly lensed binary neutron star (NS-NS) mergers are expected to be observed once LIGO/Virgo/Kagra reaches the planned A+ or proposed A\# sensitivity. We demonstrate that the relative transverse velocity of the source-lens system can be constrained by comparing the phase of the two associated gravitational wave (GW) images, using both semi-analytical and numerical Bayesian methods. For A+ sensitivity, a one-sigma NS-NS merger signal in magnification $(\mu=200)$ and redshift $(z_{\rm S}=1)$ will carry a marginally detectable dephasing signature for a source transverse velocity of $\sim 1800$ km/s. This is comparable to the velocity dispersion of large galaxy clusters. Assuming the same population distribution, the most likely source parameters of $\mu=100$ and $z_{\rm S}=1.4$ are always expected to showcase detectable dephasing imprints for A\# sensitivity, provided they are moving with transverse velocities larger than $\sim 2000$ km/s. We conclude that a first measurement of the relative transverse velocity of a source via GW dephasing methods is likely only a few years away.

When cosmic strings are formed during inflation, they regrow to reach a scaling regime, leaving distinct imprints on the stochastic gravitational wave background (SGWB). Such signatures, associated with specific primordial features, can be detected by upcoming gravitational wave observatories, such as the LISA and Einstein Telescope (ET). Our analysis explores scenarios in which cosmic strings form either before or during inflation. We examine how the number of e-folds experienced by cosmic strings during inflation correlates with the predictions of inflationary models observable in cosmic microwave background (CMB) measurements. This correlation provides a testable link between inflationary physics and the associated gravitational wave signals in a complementary manner. Focusing on $\alpha$-attractor models of inflation, with the Polynomial $\alpha$-attractor serving as an illustrative example, we find constraints, for instance, on the spectral index $n_s$ to $0.962 \lesssim n_s \lesssim 0.972$ for polynomial exponent $n=1$, $0.956 \lesssim n_s \lesssim 0.968$ for $n=2$, $0.954 \lesssim n_s \lesssim 0.965$ for $n=3$, and $0.963 \lesssim n_s \lesssim 0.964$ for $n=4$, which along with the GW signals from LISA, are capable of detecting local cosmic strings that have experienced $\sim 34 - 47$ e-folds of inflation consistent with current Planck data and are also testable in upcoming CMB experiments such as LiteBIRD and CMB-S4.

We explore the impact of spin 0, spin 1 and spin 2 Ultra-Light Dark Matter (ULDM) on small scales by numerically solving the Schrödinger-Poisson system using the time-split method. We perform simulations of ULDM for each spin, starting with different numbers of identical initial solitons and analyse the properties of the resulting halos after they merge and relax in a steady-state. Our findings reveal that higher spin values lead to broader, less dense final halo with more prominent Navarro-Frenk-White (NFW) tails, a characteristic that persists regardless of the number of initial solitons involved. We identify scaling relations that describe the density profile, core and NFW tail of spin $s$ ULDM halos as a function of the number of initial solitons $N_{sol}$. These relations allow us to construct equivalent halos based on average density or total mass, for arbitrarily large $N_{sol}$, without having to simulate those systems. We simulate the orbit of a ULDM satellite in a constructed halo treated as an external potential, and find that for host halos having the same average density, the orbital decay time of the satellite is as predicted for uniform sphere host halo regardless of the spin. However, satellites orbiting haloes having the same mass for each spin, result in faster disruption in the case of spin 0, while satellites orbiting haloes having the same core size result in faster disruption in the case of spin 2.

We probe the spectrum of primordial gravitational waves (GWs) produced during the eras of hyperkination, kination, and reheating in a non-minimally coupled, $\mathcal{L} \propto (1+ \xi \chi /M_{\text{Pl}})^t (R+\alpha R^2)$, modified gravity using the Palatini formulation. We consider a runaway potential, which gives an era of kinetic domination after the end of inflation. The coupling order $t$ is varied to examine a large class of theories up to $\chi^2 R^2$. For models with $t>0$, reheating is not achieved naturally; hence, we supplement such theories with a reheating mechanism based on the interaction of inflaton and radiation produced at the end of inflation due to cosmological expansion. We demonstrate that the energy density of the GWs is enhanced as a function of the coupling during kination for all considered theories, and a short-lived phase of hyperkination truncates the boost and avoids the over-production of GWs. Hyperkination, and thus the $R^2$ term, should be deemed necessary in all theories with a runaway potential as it prevents the GW enhancement during kination from destabilizing the Big Bang Nucleosynthesis. The spectrum remains flat for the period of hyperkination and reheating. We examine the available parameter space for which the theories remain valid and place bounds on the Hubble parameter ($H$) and radiation energy density ($\Omega_r^{\text{end}}$) at the end of inflation. We find that as we decrease the order of the coupling, the spectra shift towards a more observable regime of future GW experiments. The observation of the plateau during reheating will constrain the $H$ and $\Omega_r^{\text{end}}$ values, while the spectral shape of the boost obtained during kination will confirm the nature of the theory. The bounds from hyperkination lie in the kHz-GHz frequency range whose detection can be positively anticipated via resonant cavities.

Astrophysical observations of the cosmos allow us to probe extreme physics and answer foundational questions on our universe. Modern astronomy is increasingly operating under a holistic approach, probing the same question with multiple diagnostics including how sources vary over time, how they appear across the electromagnetic spectrum, and through their other signatures, including gravitational waves, neutrinos, cosmic rays, and dust on Earth. Astrophysical observations are now reaching the point where approximate physics models are insufficient. Key sources of interest are explosive transients, whose understanding requires multidisciplinary studies at the intersection of astrophysics, gravity, nuclear science, plasma physics, fluid dynamics and turbulence, computation, particle physics, atomic, molecular, and optical science, condensed matter and materials science, radiation transport, and high energy density physics. This white paper provides an overview of the major scientific advances that lay at the intersection of physics and astronomy and are best probed through time-domain and multimessenger astrophysics, an exploration of how multidisciplinary science can be fostered, and introductory descriptions of the relevant scientific disciplines and key astrophysical sources of interest.

Meridian circles played a fundamental role in astronomy since their invention in 1704. Then, at the end of the XX century, this function had been taken over by space astrometry, when the Hipparcos mission demonstrated the advantages of space astrometry by achieving the milliarcsecond level of accuracy. This historical sketch describes the development of the last meridian circles at Pulkovo Observatory (St. Petersburg) in the last quarter of the XX century.

We probe the effect of the ISM on debris disc occurrence rates and on the morphologies of the discs. We used results from the Herschel Space Observatory DUNES and DEBRIS surveys of 295 nearby FGK dwarf stars imaged at 100 $\mu$m and 160 $\mu$m. Most of the 48 debris discs in this sample have small optical depths, making them more likely to be affected by the ISM compared to optically thick discs. Since the stars in our sample are located within the Local Interstellar Cloud, we can infer that their debris discs encounter similar conditions. This allows us to use the stellar space velocity as a single indicator of the forces that can act on the debris disc dust grains when they interact with the ISM. The observed debris disc occurrence rates seem to depend on the stellar space velocities, as expected under the hypothesis that stars with higher space velocities have a higher probability of losing their circumstellar dust. The percentage of sources with debris discs in our sample reaches a maximum of $\approx$25% for stars with low space velocity component values, $|U_{\mathrm{rel}}|$, relative to the local ISM, and decreases for larger $|U_{\mathrm{rel}}|$ values down to the 10% level. A decrease in the average disc fractional luminosity as a function of $|U_{\mathrm{rel}}|$ is also observed. These dependences do not disappear after accounting for the reported higher dispersion of $U$ values with age. In extended discs, the impact of the ISM could also explain the links observed between the stellar space velocities and the debris disc projected ellipticities, position angles, and radii. Although these indications may not be fully conclusive on their own, they collectively reinforce the hypothesis that the ISM influences the occurrence rates and morphologies of debris discs.

Traditional neutrino detectors are built deep underground to reduce backgrounds. The neutrino solar orbiting laboratory ($\nu$SOL) collaboration has been developing a concept to improve neutrino measurement not with a larger detector underground, but instead we use the nuclear excitation from the neutrino interaction to produce a multi-pulse signal. Cerium-doped gadolinium aluminum gallium garnet (GAGG) is a new scintillator which has 23\% gallium by mass. When a neutrino interacts with the GAGG, about 10\% of the time it will be in an excited nuclear state rather than in the base energy level. A segmented detector looking for the pulses separated by distance and time has the potential to greatly limit background noise from solar wind, cosmic rays, and galactic gamma rays. A polar LEO CubeSat mission is currently in development to measure the GCR backgrounds outside the Van Allen Belts. In this summary of my presentation I will quickly lay the groundwork of the interaction of interest and what a solar orbiter's detector could look like. I will then explore what measurements a near-solar orbiter could make. With these measurements in mind, I will discuss the feasibility of a direct observation of the core's shape, and I will discuss how a solar orbiter's measurements could improve a Standard Solar Model search and compare that measurement with the current global neutrino measurements. I will conclude with a discussion of what these observables could tell us about the solar interior.

The mean apparent magnitude of Starlink Mini Direct-To-Cell (DTC) satellites observed in brightness mitigation mode is 5.16, while the mean of magnitudes adjusted to a uniform distance of 1,000 km is 6.47. The DTCs have faded since early in 2024 because SpaceX subsequently adjusted the spacecraft attitudes to dim them. A physical model for satellite brightness that fits the observations is described.

The physical origin of the radial sizes of galaxies and how galaxy sizes are correlated with the properties of their host dark matter halos is an open question in galaxy formation. In observations, the large-scale clustering of galaxies selected by stellar mass is significantly different for large and small galaxies, and Behroozi et al. (2022) showed that these results are in tension with some of the correlations between galaxy size and halo properties in the literature. We analyze the IllustrisTNG suite of large volume cosmological hydrodynamic simulations along with dark matter only simulations with matched initial conditions. We investigate correlations between the ratio of galaxy size to halo virial radius ($r_{\rm gal}/R_{\rm vir}$) and halo spin, concentration, and formation time at redshift 0-3. We find a significant correlation between $r_{\rm gal}/R_{\rm vir}$ and concentration, but only above a critical value $c \simeq 16$, and we also find a correlation between $r_{\rm gal}/R_{\rm vir}$ and halo formation time. We suggest that galaxy formation history and environment, in addition to halo properties at a given output time, play an important role in shaping galaxy size. In addition, we directly measure size-based differential clustering in the TNG300 simulation and compare directly with the observational results. We find significant scale-dependent size-based differential clustering in TNG, in qualitative agreement with observations. However, correlations between $r_{\rm gal}/R_{\rm vir}$ and secondary halo properties are not the drivers of the differential clustering in the simulations; instead, we find that most of this signal in TNG arises from satellite galaxies.

Cosmic reionization represents the latest phase transition of the intergalactic medium (IGM) in the Universe. It has long been debated whether galaxies or active galactic nuclei (AGNs) are the major source of Lyman continuum (LyC) photons responsible for reionization. Previous observations slightly favored galaxies as the major ionizing source. However, the James Webb Space Telescope (JWST) recently discovered an unexpectedly high density of AGN candidates at high redshift, which has largely enhanced the influence of AGNs. Here we derive a definitive upper bound on the AGN contribution to reionization using the latest JWST data, and conclusively rule out AGNs as the dominant ionizing source during the epoch of reionization (EoR). We build a sample of objects (including galaxies and AGNs) in a specific redshift range between 7.15 and 7.75 that has a high completeness. Each object is then decomposed into a point-source component and an extended component in their rest-frame far-UV JWST images. Assuming all point-source components are AGNs, we obtain an absolute upper limit for the density of the AGN population. This fiducial AGN sample reaches an unprecedentedly low luminosity of $M_{\rm UV} \approx -15$ mag. Based on this sample, we find that AGNs can contribute at most one third of the LyC photons required to ionize the Universe in this redshift range. Our result implies that galaxies dominate the ionizing source during the EoR.

We present a study on the possible overestimation of single-epoch supermassive black hole (SMBH) masses in previous works, based on more than 55,000 type 1 quasars at $0.25 < z < 0.8$ from the Dark Energy Spectroscopic Instrument (DESI). We confirm that iron emission strength serves as a good tracer of the Eddington ratio, and estimate SMBH masses using an iron-corrected $R$-$L$ relation for H$\beta$, where $R$ is the broad line region size and $L$ is the continuum luminosity. Compared to our measurements, previous canonical measurements without the iron correction are overestimated by a factor of 1.5 on average. The overestimation can be up to a factor of 5 for super-Eddington quasars. The fraction of super-Eddington quasars in our sample is about 5%, significantly higher than 0.4% derived from the canonical measurements. Using a sample featuring both H$\beta$ and MgII emission lines, we calibrate MgII-based SMBH masses using iron-corrected, H$\beta$-based SMBH masses and establish an iron-corrected $R$-$L$ relation for MgII. The new relation adds an extra term of $-0.34R_{\mathrm{Fe}}$ to the $R$-$L$ relation, where $R_{\mathrm{Fe}}$ denotes the relative iron strength. We use this formula to build a catalog of about 0.5 million DESI quasars at $0.6<z<1.6$. If these iron-corrected $R$-$L$ relations for H$\beta$ and MgII are valid at high redshift, current mass measurements of luminous quasars at $z\ge6$ would have been overestimated by a factor of 2.3 on average, alleviating the tension between SMBH mass and growth history in the early universe.

CO2 has been detected in both the tenuous exosphere and surface chaos regions of Europa, but it is still unclear whether this CO2 is generated in situ by radiolysis or whether it is directly delivered by the ocean. In this work, we study the radiolysis pathway, and explore the possibility that organics upwelled from the subsurface oceans could be contributing to this signature on the surface and in the exosphere. Specifically, we report here on the evolution of carbon-containing byproducts generated by electron-induced sputtering of organics with different functional groups -- hexanoic acid, hexanol, and hexane -- in water ice. We found that, upon electron irradiation in vacuum, the acid-functionalized molecules generated a factor of over 10x more CO2 than either the non-functionalized or alcohol-functionalized molecules, but that all three species produced CO2 to some extent. The amount of CO2 produced was found to depend upon temperature. CO2 was the dominant product for ices at 100 K and 120 K, and production of CO2 was 3x higher at 100 and 120 K than at 80 K. Sputtering of long chain molecules such as pentane was a factor of 100x higher in the hexanoic acid-containing ice than in the hexane/hexanol ice, suggesting that organics with carboxylic acid (COOH) functional groups may be also more likely to produce volatile species that can be ejected into the exosphere.

The tip of red giant branch (TRGB) stars have attracted intensive attention in recent years because their $I$-band absolute magnitudes, $M_\rm I$, are often used for distance calibration in the Hubble constant measurements because of its almost independence on metallicity ([Fe/H]). However, a discrepancy exists between various studies and the theoretical stellar model predicts dependence of their luminosity on [Fe/H]. Here we present a careful study of the dependence of absolute magnitudes and color indexes on metallicity in optical and near-infrared bands. With the TRGB stars identified in 33 Galactic globular clusters by the reddest color in the $G_{\rm BP}-G_{\rm RP}$ vs. $G_{\rm RP}$ diagram, it is confirmed that $M_\rm I$ is almost constant of $-4.017 \pm 0.036 \pm 0.027$ mag when $[\rm Fe/H]<-1.2$, which would give $H_0=70.86\pm 1.2\pm0.9$ $\rm kms^{-1} Mp c^{-1}$ with this updated luminosity calibration for type Ia supernovae. However, for $[\rm Fe/H]>-1.2$, $M_\rm I$ is found to become fainter with lower metallicity, which would lead to a larger Hubble constant. In the optical $G_{\rm BP}, G_{\rm RP}$ and $V$ bands, the absolute magnitude of TRGB stars tends to increase with metallicity, while in the infrared $J, H$, and $K_{\rm S}$ bands, the variation with metallicity shows an inverse tendency. In addition, the analytical relations of the color indexes with metallicity are presented, which have smaller dispersion than those derived for the corresponding absolute magnitudes.

The impact of active galactic nuclei (AGN) on the evolution of galaxies explains the steep decrease in the number density of the most massive galaxies in the Universe. However, the fueling of the AGN and the efficiency of this feedback largely depend on their environment. We use data from the Low Frequency Array (LOFAR) Two-metre Sky Survey Data Release 2 (LoTSS DR2), the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, and the Sloan Digital Sky Survey (SDSS) DR12 to make the first study of the orientations of radio jets and their optical counterpart in relation to the cosmic web environment. We find that close to filaments ($\lesssim 11 \,\rm Mpc$), galaxies tend to have their optical major axes aligned with the nearest filaments. On the other hand, radio jets, which are generally aligned perpendicularly to the optical major axis of the host galaxy, show more randomised orientations with respect to host galaxies within $\lesssim 8 \,\rm Mpc$ of filaments. These results support the scenario that massive galaxies in cosmic filaments grow by numerous mergers directed along the orientation of the filaments while experiencing chaotic accretion of gas onto the central black hole. The AGN-driven jets consequently have a strong impact preferentially along the minor axes of dark matter halos within filaments. We discuss the implications of these results for large-scale radio jet alignments, intrinsic alignments between galaxies, and the azimuthal anisotropy of the distribution of circumgalactic medium and anisotropic quenching.

The unprecedented sensitivity of the \textit{James Webb Space Telescope} (\textit{JWST}) has revolutionized our understanding of the early universe. Among the most intriguing \textit{JWST} discoveries are red, very compact objects showing broad line emission features nicknamed as little red dots (LRDs). The discovery of LRDs has triggered great interest about their origin as either extremely starbursting galaxies or highly-obscured active galactic nuclei (AGN). Their exact nature still remains unknown. The goal of this work is to estimate the radio emission from LRDs and predict which radio surveys would detect them. To achieve these objectives, we employ the fundamental plane of black hole (BH) accretion to estimate radio emission from AGN and the stellar radio fluxes from their host galaxies. We assume a range of BH mass, X-ray luminosity ($\rm L_{X}$) and star formation rate (SFR) to bracket the likely properties of LRDs. Our findings suggest that BH radio fluxes from LRDs are 10-100 times higher than the stellar fluxes from their host galaxies, depending on BH mass, $\rm L_X$ and SFR. The detection of a $\sim$ 500 nJy signal above 2 GHz at $z \geq$ 5 or a $\sim$ 2000 nJy flux at $z =$ 3-4 would be a smoking gun for the presence of AGN provided that SFRs in the host galaxies are $\rm < 30~ M_{\odot} ~yr^{-1}$. We find that LRDs are most likely radio quiet AGN otherwise would have been already detected in the current radio surveys. Our findings suggest that LRDs can be detected with the upcoming radio observatories such as ngVLA and SKA with integration times of 10-100 hrs, respectively.

Compton-thick active galactic nuclei (CT-AGNs), characterized by a significant absorption with column densities of $\mathrm{N_H}\geqslant 1.5\times 10^{24} \ \mathrm{cm}^{-2}$, emit feeble X-ray radiation and are even undetectable by X-ray instruments, making them difficult to identify. X-ray radiation from AGNs is the predominant source of the cosmic X-ray background (CXB). Based on AGN synthesis models for the CXB, the fraction of CT-AGNs should constitute a substantial portion of AGN population, approximately 30\% or more. The fraction of CT-AGNs discovered in the Cosmological Evolution Survey (COSMOS) is significantly lower than this value. This means that many CT-AGNs may be hidden in AGNs that exhibit low photon counts or that have not been detected by X-ray instruments. This work focuses on identifying CT-AGNs hidden in AGNs with low photon counts. Firstly, we selected 440 AGNs with abundant multiwavelength data as our sample. Secondly, we analyzed multiwavelength data, extracting crucial physical parameters required for the CT-AGN diagnosis. Finally, we used multiwavelength approaches to identify CT-AGNs. We have successfully identified 18 CT-AGNs in our sample. Among the CT-AGNs, four AGNs show discrepant results across different diagnostic methods. We discuss the potential reasons behind these diagnostic discrepancies. We explore the impact of estimating [O~III]$\lambda~5007$ luminosities based on [O~II]$\lambda~3727$ luminosities for the CT-AGN diagnosis. We have also found that the properties of host galaxies for CT-AGNs and non-CT-AGNs do not show significant discrepancies.

Drone-based beam measurements are a promising avenue to tackle the critical challenge of calibration for 21 cm cosmology telescopes. In this paper, we introduce a new drone-based calibration system for 400-800 MHz radio observatories, describing its instrumentation and first deployment. We discuss measurements of the TONE array, a CHIME/FRB outrigger pathfinder, and present results, including full 2D high spatial resolution beam maps in both co- and cross-polarization, as well as comparisons to simulations. The polarized beam maps cover a 70 degree by 70 degree grid, capturing the first two sidelobes and measuring the TONE main beam and first sidelobe with 7-9% statistical errors. We investigate polarization angle alignment with frequency, finding significant polarization leakage in the TONE antennas at frequencies above 600 MHz, and a polarization axis rotation with frequency. We describe statistical and systematic errors, as well as measurements of radio frequency interference from the drone and equipment. Our drone system is the first to incorporate a broad-band switched calibration source in the drone payload, enabling background subtraction and direct measurements of the RFI emitted by the drone. The results presented are the first drone-based 2D measurements of cross-polar beam structure and of polarization alignment of an array. The high frequency and spatial resolution achieved with this system have revealed the rich structure of the beam of each antenna, and enabled comparisons between individual dishes and to electromagnetic simulations.

We report the search of RR Lyrae in the vicinity of a newly discovered ultrafaint dwarf galaxy, Aquarius III. Based on the known RR Lyrae catalogs and $gri$-band light curves retrieved from public archives, we identified a RR Lyrae with distance, metallicity, and proper motion consistent with Aquarius III. Therefore, this RR Lyrae is the first variable star identified to be associated with Aquarius III, despite its projected distance is more than 15 times the half-light radius of Aquarius III. On the other hand, a dedicated time-series monitoring of the central part of Aquarius III, out to a projected radius of approximately four half-light radius, revealed there is no RR Lyrae in this region. We ran a set of synthetic color-magnitude diagrams with properties similar to Aquarius III, and found a non-negligible probability that Aquarius III could have (at least one) RR Lyrae. We have also identified a RR Lyrae candidate but most likely it is a background halo star.

Solar radio observation is an important way to study the Sun. Solar radio bursts contain important information about solar activity. Therefore, real-time automatic detection and classification of solar radio bursts are of great value for subsequent solar physics research and space weather warnings. Traditional image classification methods based on deep learning often require consid-erable training data. To address insufficient solar radio spectrum images, transfer learning is generally used. However, the large difference between natural images and solar spectrum images has a large impact on the transfer learning effect. In this paper, we propose a self-supervised learning method for solar radio spectrum classification. Our method uses self-supervised training with a self-masking approach in natural language processing. Self-supervised learning is more conducive to learning the essential information about images compared with supervised methods, and it is more suitable for transfer learning. First, the method pre-trains using a large amount of other existing data. Then, the trained model is fine-tuned on the solar radio spectrum dataset. Experiments show that the method achieves a classification accuracy similar to that of convolutional neural networks and Transformer networks with supervised training.

Solar radio observation is a method used to study the Sun. It is very important for space weather early warning and solar physics research to automatically classify solar radio spectrums in real time and judge whether there is a solar radio burst. As the number of solar radio burst spectrums is small and uneven, this paper proposes a classification method for solar radio spectrums based on the Swin transformer. First, the method transfers the parameters of the pretrained model to the Swin transformer model. Then, the hidden layer weights of the Swin transformer are frozen, and the fully connected layer of the Swin transformer is trained on the target dataset. Finally, pa-rameter tuning is performed. The experimental results show that the method can achieve a true positive rate of 100%, which is more accurate than previous methods. Moreover, the number of our model parameters is only 20 million, which is 80% lower than that of the traditional VGG16 con-volutional neural network with more than 130 million parameters.

We report the GeV $\gamma$-ray emission around the composite supernova remnant (SNR) CTB 87 with more than 16 yrs PASS 8 data recorded by the Fermi Large Area Telescope. Two separate point sources with the different GeV spectra are identified in this region: one has a soft $\gamma$-ray spectrum, likely due to interactions between the SNR shock and molecular clouds (MCs); and another source with a hard GeV $\gamma$-ray spectrum aligns with the TeV spectrum of VER J2016+371, suggesting it as the GeV counterpart. Considering the observations of CTB 87 in the radio and X-ray bands, VER J2016+371 is proposed to originate from the pulsar wind nebula (PWN) associated with PSR J2016+3711. A leptonic model with a broken power-law electron distribution could explain the multi-wavelength data of VER J2016+371, with fitted parameters matching typical $\gamma$-ray PWNe. Deeper searching for the SNR shock of CTB 87 in other bands and the future TeV observations by LHAASO and CTA are crucial to reveal the nature of CTB 87.

We detail the emission behaviors of three long-period pulsars detected using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) during the CRAFTS survey. Their rotational periods range from 1.83 s to 4.75 s, and the null fractions measure between 28% and 53%. PSR J1945+1211 and PSR J2323+1214 exhibited quasi-periodic nulls, with duration of around 57 seconds. The longest null was observed in PSR J1945+1211, lasting 76 seconds. PSR J2323+1214 displayed varying null fractions between its leading and trailing components. For the first time in PSR J2323+1214, we detected five dwarf pulses, which are much weaker and narrower pulses than typical burst pulses. In addition, we investigate the microstructure of PSR J1900-0134 for the first time, revealing intricate pulses of up to 2.05 milliseconds and noting its complex emission characteristics. Bright pulses occur in all of these sources at different rates. These observations suggest complex magnetospheric processes, potentially related to magnetic reconnections, and provide insights into the origins of bright and microstructure pulses, as well as their distinctions from ordinary pulses.

We investigate properties of the emission region as revealed by drifting subpulses of opposite drift directions at different parts of a pulse profile by using the rotating carousel model in an obliquely rotating pulsar magnetosphere of multiple emission states. Subpulse emission is assumed coming from m discrete emission areas that are distributed around the magnetic axis on a rotating carousel. The flow rate of the emission areas is determined by the E x B drift in an emission state, designated by the parameter y, in which E and the associated flow rate are dependent on y. In this model, subpulses appear to drift in an emission state if a relative speed exists between the plasma flow and corotation, and the diversity in the drift rates and directions corresponds to the relative speed being different in different parts of a profile. We apply the model to three pulsars that exhibit drifting subpulses of opposite drift directions to identify the emission states and the values of m. Our results show that different drifting subpulses correspond to particular values of m and y, and the latter implies that different emission states can coexist and operate concurrently in an emission region. We find that m does not show clear dependency on either the obliquity angle or emission state. We demonstrate that subpulse arrangement may vary across an emission region meaning that it is not always uniform on a carousel. We discuss drifting subpulses of opposite drift directions and subpulse drift-rate switching in terms of different emission states in our model, and speculate that they may be two manifestations of the same underlying mechanism.

Luminous Infrared Galaxies (LIRGs) play a crucial role in understanding of galaxy evolution. The present study examined 82 LIRGs, using data taken from the Sloan Digital Sky Survey (SDSS), NASA/IPAC Extragalactic Database (NED), and HyperLEDA to explore their gas fractions and optical properties. The analysis of data highlights the relationship between molecular-to-atomic mass of hydrogen gas ratio MH2/MH1 and morphological types, gas mass fractions, and galaxy characteristics such as color and luminosity. The results showed that the regressions between Mdust - M*,V and Mdust - SFR are not quite flat (when correlation coefficient > 0.5), which indicates a decrease in the dust-to-stellar content ratio as the gas is consumed and transformed into stars, and also a relatively flat trend for M dust - M*,V and fdust,bar - M*,V. Moreover, as the star mass declines, the total gas mass fraction (fgas) increases quickly, with a high negative correlation coefficient of - 0.7 and a regression of - 0.85. Therefore, it can be inferred that galaxies with a high gas fraction (fgas) are either accreting gas at a rate sufficient to meet their energy requirements for star formation or converting gas into stars less effectively. According to the findings, the gas exhaustion time in these galaxies quickly reduces as the stellar mass increases, with a significant negative correlation coefficient of - 0.7 and a regression that is a nearly linear regression of - 0.9. On the other hand, when the baryonic gas mass fraction grows, which makes up the majority of the baryonic gas, grows, the gas depletion time increases quickly.

While the sources of the diffuse astrophysical neutrino flux detected by the IceCube Neutrino Observatory are still largely unknown, one of the promising methods used towards understanding this is investigating the potential temporal and spatial correlations between neutrino alerts and the electromagnetic radiation from blazars. We report on the multiwavelength target-of-opportunity observations of the blazar B3 2247+381, taken in response to an IceCube multiplet alert for a cluster of muon neutrino events compatible with the source location between May 20, 2022 and November 10, 2022. B3 2247+381 was not detected with VERITAS during this time period. The source was found to be in a low-flux state in the optical, ultraviolet and gamma-ray bands for the time interval corresponding to the neutrino event, but was detected in the hard X-ray band with NuSTAR during this period. We find the multiwavelength spectral energy distribution is well described using a simple one-zone leptonic synchrotron self-Compton radiation model. Moreover, assuming the neutrinos originate from hadronic processes within the jet, the neutrino flux would be accompanied by a photon flux from the cascade emission, and the integrated photon flux required in such a case would significantly exceed the total multiwavelength fluxes and the VERITAS upper limits presented here. The lack of flaring activity observed with VERITAS, combined with the low multiwavelength flux levels, and given the significance of the neutrino excess is at 3$\sigma$ level (uncorrected for trials), makes B3 2247+381 an unlikely source of the IceCube multiplet. We conclude that the neutrino excess is likely a background fluctuation.

Studies on star clusters with the same age and initial chemical composition have gained momentum in recent years with the use of \textit{Gaia}. In addition, the discovery of new clusters with Gaia has increased the number of open clusters to be examined. Many of these discovered sources are intermediate-age open clusters and have not been analyzed in detail yet. In this study, we focused on newly cataloged open cluster UPK~220. The fundamental parameters (distance, age, metallicity and reddening) of UPK~220 were determined by analysing the variable stars within the cluster, while simultaneously constraining the parameters of the variable stars using these cluster parameters. To achieve this, we combined GaiaDR3 and TESS photometric observations. Using GaiaDR3, we derive fundamental parameters of UPK~220 through membership analyses, and with TESS, we discovered eight member variable stars. We also extracted the atmospheric parameters ($logg$, $[Fe/H]$ and $T_{\rm eff}$) for the variable stars using SED, GSP-Phot and GSP-Spec, and MESA models.

The central molecular zone (CMZ) of our Galaxy exhibits widespread emission from SiO and various complex organic molecules (COMs), yet the exact origin of such emission is uncertain. Here we report the discovery of a unique class of long ($>$0.5 pc) and narrow ($<$0.03 pc) filaments in the emission of SiO 5$-$4 and eight additional molecular lines, including several COMs, in our ALMA 1.3 mm spectral line observations toward two massive molecular clouds in the CMZ, which we name as slim filaments. However, these filaments are not detected in the 1.3 mm continuum at the 5$\sigma$ level. Their line-of-sight velocities are coherent and inconsistent with being outflows. The column densities and relative abundances of the detected molecules are statistically similar to those in protostellar outflows but different from those in dense cores within the same clouds. Turbulent pressure in these filaments dominates over self gravity and leads to hydrostatic inequilibrium, indicating that they are a different class of objects than the dense gas filaments in dynamical equilibrium ubiquitously found in nearby molecular clouds. We argue that these newly detected slim filaments are associated with parsec-scale shocks, likely arising from dynamic interactions between shock waves and molecular clouds. The dissipation of the slim filaments may replenish SiO and COMs in the interstellar medium and lead to their widespread emission in the CMZ.

Thin stellar streams, such as those resulting from the tidal disruption of globular clusters, have long been known and used as probes of the gravitational potential of our Galaxy, both its visible and dark contents. In particular, the presence of under-density regions, or gaps, along these streams is commonly interpreted as being due to the close passage of dark matter sub-halos. In this work, we investigate the perturbations induced on streams by the passage of dense stellar systems, such as globular clusters themselves, to test the possibility that they may cause the formation of gaps as well. In particular, we focus on the study of the stream of Palomar 5, a well-known globular cluster in the Galactic halo, which has particularly long tidal tails. For this purpose, we used a particle-test code to simulate Palomar 5's tidal tails when subjected to the Galaxy's gravitational field plus its whole system of globular clusters. Our study shows that the tails of Palomar 5 can be strongly perturbed by the close passage of other clusters, in particular of NGC 2808, NGC 7078, NGC 104, and that these perturbations induce the formation of gaps in the tails. These results show that globular clusters are capable of inducing gaps in streams--as other baryonic components such as giant molecular clouds and the galactic bar have been shown to do in other works. Therefore, when searching to construct the distribution function of dark matter sub halos within the Milky Way, the gap contribution from globular clusters must be included.

We present a detailed systematic pulse search for three Intermittent-Accreting Millisecond X-ray Pulsars (Intermittent-AMXPs), HETE J1900.1-2455, SAX J1748.9-2021 & Aql X-1, via Z$_1^2$ and maximum likelihood (ML) techniques by using 16 years data of Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) in the energy range of 3.0 - 13.0 keV. We first performed a pulse scan using the Z$_1^2$ technique in millisecond sensitivities for every 25 s time interval with 1 s shifts to cover all data set around the detected frequencies given in the literature. We tracked the Z$_1^2$ power over time and flagged the time intervals exceeding defined threshold levels for each source as \textit{pulse candidates}. The detected pulse list throughout our scan has new discoveries while covering the pulsed regions presented in the literature. For a deeper search, using the pulses obtained from the Z$_1^2$ method as a probability density function as an input parameter, we re-scanned the time intervals centered on the detected pulse via ML. The detected pulse-on duration via ML is slightly longer than the one via Z$_1^2$ method. This phenomenon allows us to argue for the existence of the smooth transition between pulse-on and pulse-off stages. For SAX J1748.9-2021, we also obtained orbital period by using the systematic pulse arrival phase patterns throughput of ML to be 8.76 hours.

A superconducting quantum interference device (SQUID), functioning as a nonlinear response device, typically requires the incorporation of a flux-locked loop (FLL) circuit to facilitate linear amplification of the current signal transmitted through a superconducting transition-edge sensor (TES) across a large dynamic range. This work presents a reasonable model of the SQUID-FLL readout system, based on a digital proportional-integral-differential (PID) flux negative feedback algorithm. This work investigates the effect of $V$-$\phi$ shape on the performance of digital FLL circuits. Such as the impact factors of bandwidth, design limits of slew rate of the system and the influence of the shapes of SQUID $V$-$\phi$ curve. Furthermore, the dynamic response of the system to X-ray pulse signals with rise time ranging from $4.4{\sim}281$ $\mathrm{{\mu}s}$ and amplitudes ranging from $6{\sim}8$ $\mathrm{\phi_0}$ was simulated. All the simulation results were found to be consistent with the existing mature theories, thereby validating the accuracy of the model. The results also provide a reliable modelling reference for the design of digital PID flux negative feedback and multiplexing SQUID readout electronic systems.

X-ray inter-band time lags are observed during the outbursts of black hole X-ray binaries (BHXRBs). Timing analysis of fast variability in low Fourier frequency bands shows that high-energy photons lag behind low-energy photons, a phenomenon referred to as hard lag. Conversely, in high Fourier frequency bands, low-energy photons lag behind high-energy photons, known as soft lag. This frequency-dependent lag spectrum suggests that the lags arise from different physical processes. Notably, a trend has been observed wherein the lags shift towards shorter timescales during the rising hard state, indicating an evolution in the inner accretion flow. In this study, we simulate these inter-band lags by conducting Monte Carlo simulations of the rapid variability within the geometry of a jet base corona. We consider both inward propagating accretion rate fluctuations and reverberation (light crossing) delays in our simulations. We successfully reproduce both low-frequency hard lags and high-frequency soft lags in a self-consistent manner. We replicate the observed evolution of the frequency-dependent lag spectra by varying the geometrical scale of the corona and the viscous frequency of the disc. Finally, we discuss the potential of a spherical corona and emphasize that polarization observations from the Imaging X-ray Polarimetry Explorer (IXPE) and the enhanced X-ray Timing and Polarimetry mission (eXTP) will be crucial for distinguishing the corona's geometry in future studies.

We investigate the flux intensities spanning from radio waves to X-rays across 39 light curves of Quasar 3C 273, utilizing publicly available data collected by the Integral Science Data Centre (ISDC) database. Our results suggest that Quasar 3C 273 exhibits nonextensive behavior. Furthermore, we calculate the $q$ entropic indices for these light curves using the $q$-Gaussian distribution with a predominant observation of cases where $q>1$. Based on this index, we estimate the non-extensive entropy ($S_{q}$) and explore its correlation with the energy (in eV). In this context, we identify two jump-like increases in entropy, particularly evident in the infrared (IR) and X-ray wavebands. The peak in the far-IR band, around 0.34 eV, results from synchrotron flares evolving from higher to lower energies and thermal radiation emitted by hot dust near the sublimation radius. However, the second entropic peak in the hard X-ray range lacks statistical robustness due to limited data or large measurement uncertainties.

The size distribution of trans-Neptunian objects (TNOs) in the Kuiper Belt provides crucial insights into the formation and evolution of the outer Solar System. Recent observational surveys, including OSSOS++, have revealed that dynamically cold and hot TNO populations exhibit similar size distributions for dimmer objects ($H_r > 5$), which are consistent with planetesimal formation by streaming instability (SI). However, the hot population contains a significantly larger number of massive bodies, including several dwarf planets. In this study, we investigate the role of pebble accretion in shaping the size distribution of hot TNOs, after their formation in the primordial disk (PB) between 20 and 30 au and before these bodies were dynamically implanted into their current orbits by a migrating Neptune. We find that pebble accretion grows the most massive bodies only, consistent with the flattening of the distribution brightwards of $H_r=5$. All results point to a correlation (degeneracy) between the pebble aerodynamic size and the intensity of the gas motions. Nevertheless, accretion from an inward-drifting stream of pebbles is unlikely, as it puts extreme demands on the mass budget of pebbles. In particular, the masses of the cold classicals are too low to trigger pebble accretion. Accretion in an environment where pebbles are entrained, as believed to be the case in ALMA rings, is preferable. Combining the constraints obtained from this study with ALMA imagery morphology fitting reveals a typical pebble aerodynamic size of $\tau_s \sim 10^{-2}$, a turbulent diffusivity parameter $\alpha_D\sim10^{-3}$, and a total accreted pebble mass of ${\sim}10\,m_\oplus$ in the primordial belt. Those TNOs formed through significant pebble accretion with masses exceeding ${\sim}10^{-4}\,m_\oplus$ are likely to satisfy the International Astronomical Union's "round shape" criterion for dwarf planets.

The Square Kilometre Array (SKA) Observatory is gearing up the formal construction of its two radio interferometers in Australia and South Africa after the end of design and pre-construction phases. Agile methodologies, the Cloud native Computing technologies and the DevOps software ideas are influencing the design of compute infrastructures that will be key to reduce the operational costs of SKA while improving the control and monitoring of the SKA antennas and ancillary systems, Correlators, HPC facilities or related data centre tiered systems. These tools will likely include advanced power metering technologies and efficient distribution automation and Network Operation Centres (NOC). SKA will become the world's largest radio telescope and is expected to achieve its first science by 2026. To cope with this dimension and complexity, a key part of this distributed Observatory is the overall software control and monitoring system embodied in the Observatory Management and Control (OMC) and the Services Teams that requires specialized Agile Teams to assist in software and cyber infrastructure building using an Agile development environment that includes test automation, Continuous Integration, and Continuous Deployment. To manage such a large and distributed machine, the Agile approach was adopted for the core software package of the SKA Telescope aimed at scheduling observations, controlling their execution, monitoring the telescope status and ensuring scalability and reliability. Here, we report on the ENGAGE SKA ciberinfrastructure prototyping support to the SKA Agile Software Development Life Cycle (SDLC).

We present fresh insights into the nature of the tidal disruption event (TDE) candidate AT 2018dyk. AT 2018dyk has sparked a debate in the literature around its classification as either a bona-fide TDE or as an active galactic nucleus (AGN) turn-on state change. A new follow-up spectrum taken with the Dark Energy Spectroscopic Instrument, in combination with host-galaxy analysis using archival SDSS-MaNGA data, supports the identification of AT 2018dyk as a TDE. Specifically, we classify this object as a TDE that occurred within a gas-rich environment, which was responsible for both its mid-infrared (MIR) outburst and development of Fe coronal emission lines. Comparison with the known sample of TDE-linked extreme coronal line emitters (TDE-ECLEs) and other TDEs displaying coronal emission lines (CrL-TDEs) reveals similar characteristics and shared properties. For example, the MIR properties of both groups appear to form a continuum with links to the content and density of the material in their local environments. This includes evidence for a MIR colour-luminosity relationship in TDEs occurring within such gas-rich environments, with those with larger MIR outbursts also exhibiting redder peaks.

Symbiotic stars serve as exceptional laboratories for investigating mass transfer processes in binary systems. However, the dominant mechanism of mass transfer from the red giant donor to the compact accretor - typically a white dwarf or, in rare cases, a neutron star - remains unclear. It is uncertain whether it is driven primarily by the stellar wind, Roche-lobe overflow, or a combination of the two. While radii inferred from rotational velocities or spectral types suggest smaller Roche-lobe filling factors, the presence of ellipsoidal variability, presumably caused by tidally deformed giants in many symbiotic systems, indicates the opposite. Interferometric observations of symbiotic giants, combined with distance measurements provided by the Gaia mission, offer a promising avenue to resolve this discrepancy. In this first paper of the series, we (re)analyze VLTI/PIONIER observations of six symbiotic stars: AG Peg, FG Ser, ER Del, V1261 Ori, RW Hya, and V399 Pav. With the exception of the uncertain case of V399 Pav, we find that the giants in these systems remain well within their canonical Roche lobes, even in V1261 Ori and RW Hya, where ellipsoidal variability is observed. All six stars appear to be rather luminous and likely located on the asymptotic giant branch, although the possibility of some of them being at the tip of the first red giant branch cannot be ruled out.

Dwarf galaxies play an important role in studying the effects of the environment on galaxy formation and evolution. In this study, we aim to explore the relationship between the morphology, in particular the asymmetries of galaxies, and their distances to the cluster centre. For galaxies in the Fornax Deep Survey, we quantified the morphologies of dwarf galaxies using Asymmetry (A) and Smoothness (S). Unlike previous work, we use isophotal CAS-parameters, which are sensitive to the outer parts of galaxies. We constructed the A-r and S-r diagrams to investigate the relationship between morphology and distance. Additionally, we examined the effects of asymmetry on magnitude and colour. Furthermore, to better understand the assembly history of the galaxy cluster, we performed a phase-space analysis for Fornax dwarf galaxies. We find that dwarf galaxies in the outer regions of the Fornax cluster have higher values of asymmetry compared to other dwarfs in the cluster, indicating a greater degree of morphological disturbances within dwarf galaxies in these regions. We also find that galaxies in the very inner regions are more asymmetric than those further out. The A-magnitude relation reveals a trend where asymmetry increases as galaxies become fainter, and the A-colour relation shows that galaxies with bluer colours tend to exhibit higher asymmetry. We do not find any correlations with smoothness, except that smoothness strongly decreases with stellar mass. We propose that the higher asymmetry of dwarfs in the outer regions is most likely caused by ram pressure stripping. In the very inner parts, the asymmetries most likely are caused by tidal effects. In addition, our phase-space diagram suggests that galaxies near pericentre in the Fornax cluster exhibit significantly higher asymmetry, indicating that morphological disturbances happened during their first pericentric passage.

Solar prominences are very spectacular structures embedded in the tenuous and hot solar corona. The counterstreaming flows, a common feature in solar quiescent prominences, have been discovered for more than twenty years. However, the mechanism driving the counterstreaming flows is still elusive. To unveil the nature of this phenomenon, we analyzed the data of a quiescent prominence observed by the New Vacuum Solar Telescope (NVST), the Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamical Observatory (SDO). It is found that there is a distinct longitudinal oscillation of prominence plasma along the higher part of the prominence spine in H$\alpha$ observations. The oscillation period is approximately 83 minutes and the amplitude is about 32 Mm. The counterstreaming flows are dominant in the middle part of the prominence spine. The velocities of the counterstreaming flows range from about 4 km s$^{-1}$ to 11 km s$^{-1}$. Moreover, the intermittent mass flows with the upward plumes from the top of the bubbles and tornado-like barbs are observed to be injected into the lower part of the prominence spine from the lower atmosphere. The velocities of these injected mass flows range from about 3 km s$^{-1}$ to 30 km s$^{-1}$. Some injected mass flows exhibit redshifted Doppler signals, while others exhibit blueshifted signals. Based on these high resolution observations, it is found that different parts of the prominence spine exhibit the different dynamic characteristics. These results further advance the understanding of the ubiquitous counterstreaming flows in solar quiescent prominences.

The gamma-ray emission from Flat Spectrum Radio Quasars (FSRQs), a sub-class of blazars, is believed to be generated through interactions of high-energy leptons and/or hadrons in the jet with the ambient photon fields, including those from the accretion disk, the broad line region (BLR), and the dusty torus. However, these same photon fields can also attenuate gamma-rays through internal photon-photon (gamma-gamma) absorption, imprinting characteristic spectral features. Investigating the internal absorption is crucial for unraveling the complex structure of FSRQs and constraining the poorly known location of the gamma-ray emission region. In this study, we select a sample of gamma-ray detected FSRQs with high redshift (z >= 3), to search for absorption features appearing at lower photon energies due to a substantial redshift. We extract the Fermi-LAT gamma-ray spectra of these sources and perform physical modeling using a detailed gamma-gamma opacity model, assuming that the BLR photon field dominates the absorption and focusing on the energy range ~25 GeV/(1+z), where the absorption feature due to Ly{\alpha} photons is expected. Our analysis reveals a hint of internal absorption for one source (the lowest redshift object in our sample, z~3) and provides constraints on the location of its gamma-ray emitting region along the jet. For the remaining, higher-redshift sources, the limited photon statistics prevent a reliable detection of internal opacity features.

Diffusion models have been used in cosmological applications as a generative model for fast simulations and to reconstruct underlying cosmological fields or astrophysical images from noisy data. These two tasks are often treated as separate: diffusion models trained for one purpose do not generalize to perform the other task. In this paper, we develop a single diffusion model that can be used for both tasks. By using the Diffusion Posterior Sampling (DPS) approach, we use a diffusion model trained to simulate weak lensing maps for the inverse problem of reconstructing mass maps from noisy weak lensing data. We find that the standard DPS method leads to biased inference but we correct this bias by down weighting the likelihood term at early sampling time steps of the diffusion. Our method give us a way to reconstruct accurate high-resolution (sub-arcminute) mass maps that have the correct power spectrum and a range of non-Gaussian summary statistics. We discuss several applications enabled by the computational efficiency and accuracy of our model. These include generation of simulation quality mass maps, aiding covariance estimation for higher order statistics, and for finding filaments, voids and clusters from noisy lensing shear data.

Hot Jupiters are typically considered to be tidally locked due to their short orbital periods. The extreme irradiation can result in atmospheric species becoming thermally ionized on the dayside, which then interact with the planet's magnetic field by resisting flow across magnetic field lines, shaping the atmospheric structure. However, an eccentric orbit results in temporally dependent irradiation and a non-permanent dayside, as the planet-star distance can change drastically during its orbit. In this paper, we present 3D atmospheric models of TOI-150b, an eccentric (e=0.26), Jupiter-mass 1.75 M_Jup planet whose equilibrium temperature varies from 1300K to 1700K. We conduct simulations for magnetic field strengths ranging from 0-30 Gauss using the kinematic magnetohydrodynamics (MHD) approach. When compared to simulations of the planet assuming a circular orbit, we find that the eccentric orbit results in a strengthened and narrowed equatorial jet, westward winds at mid-latitudes, and a phase-dependent thermal inversion. The strength and magnitude of these effects scale with the chosen global magnetic field strength. We also generate high-resolution (R=100,000) emission spectra to study net Doppler shifts and find inter-orbit spectroscopic variability at moderate magnetic field strengths, as well as decreased Doppler broadening as magnetic field strengths increase. This work represents the first time that the kinematic MHD approach has been applied to an eccentric hot Jupiter and highlights the importance of a locally calculated, temperature dependent magnetic drag prescription for predicting atmospheric structure and resulting spectra.

It has previously been found that the galaxy cluster environment can affect the fueling and evolution of Active Galactic Nuclei (AGN). This work examines the effect of the merging cluster environment on the properties of radio-AGN by comparing the radio morphology of cluster members in a sample of four merging and eight relaxed galaxy clusters at low redshift (z<0.2). Using 144-MHz data from the LOFAR Two-metre Sky Survey (LoTSS) and Zooniverse, we classify the radio morphology of the radio-detected cluster members using the following morphology classes: compact, compact extended, extended, jetted, and disturbed. We find that the merging cluster environment has a statistically significant, higher population proportion of disturbed (bent and head tail) sources, indicating that the merging environment can affect the morphology of cluster radio-AGN. We also investigate the number of AGN that are detected in the radio data only, and the number that are detected in both the radio and optical data in mergers and non-mergers. We find that the merging cluster environment has a higher population proportion of AGN that are identified only as radio-AGN compared to AGN that are identified as both radio and optical AGN. Overall, we find that the merging environment affects certain radio-AGN (disturbed and only radio identified AGN), but not all.

Recently, a $\sim3.9\sigma$ preference for dynamical dark energy from the Dark Energy Spectroscopic Instrument (DESI) collaboration inspired hot debates on new physics or systematics. In this letter, we reveal this significant preference is dominated by an external low-redshift supernova (low-$z$ SN) sample that combines with the Dark Energy Survey SN program (DES-SN) in their Year 5 data release (DESY5). Further implementing the $a_B$ (the intercept of the SN magnitude-redshift relation) diagnosis between low-$z$ and DES-SN samples, we find large dispersions in the low-$z$ SN sample with a $\sim0.043$ magnitude discrepancy in $-5a_B$ from the high-$z$ DES-SN sample, suggesting potential systematics in DESY5. Correcting for this low-$z$ systematics or directly ignoring the low-$z$ sample can largely reduce the preference for dynamical DE to be $<2\sigma$. Therefore, the DESI preference for dynamical DE might be a mirage of low-$z$ SN systematics with a mismatch intercept. Our additional test demonstrates the currently available data cannot provide decisive evidence for dynamical DE.

Emulators using machine learning techniques have emerged to efficiently generate mock data matching the large survey volume for upcoming experiments, as an alternative approach to large-scale numerical simulations. However, high-fidelity emulators have become computationally expensive as the simulation volume grows to hundreds of megaparsecs. Here, we present a {\it multi-fidelity} emulation of large-scale 21~cm lightcone images from the epoch of reionization, which is realized by applying the {\it few-shot transfer learning} to training generative adversarial networks (GAN) from small-scale to large-scale simulations. Specifically, a GAN emulator is first trained with a huge number of small-scale simulations, and then transfer-learned with only a limited number of large-scale simulations, to emulate large-scale 21~cm lightcone images. We test the precision of our transfer-learned GAN emulator in terms of representative statistics including global 21~cm brightness temperature history, 2D power spectrum, and scattering transform coefficients. We demonstrate that the lightcone images generated by the transfer-learned GAN emulator can reach the percentage level precision in most cases on small scales, and the error on large scales only increases mildly to the level of a few tens of per cent. Nevertheless, our multi-fidelity emulation technique saves a significant portion of computational resources that are mostly consumed for generating training samples for GAN. On estimate, the computational resource by training GAN completely with large-scale simulations would be one to two orders of magnitude larger than using our multi-fidelity technique. This implies that our technique allows for emulating high-fidelity, traditionally computationally prohibitive, images in an economic manner.

For a new parameterization of the modified effective chiral model, developed primarily to regulate the density content of the symmetry energy and its higher order terms, equations of state (EoSs) for hyperon-rich matter ($H$) and delta baryon matter ($\Delta$) were obtained. The models were used to investigate the emission of gravitational waves (GWs) through $f$-mode oscillations in the corresponding neutron stars. We obtained the stellar structure, $f$-mode frequency and tidal deformability $\Lambda$ for our models. We report that the $\Delta$ EoS is stiffer compared to the $H$ EoS. We also analyzed the velocity of sound in these media. The corresponding mass--radius relationships were obtained and compared with various observations. We studied the dependence of $f$-mode frequencies on the stellar mass, redshift and tidal deformability. We employed the well known Cowling approximation to obtain the $f$-mode frequencies for $l=2,\,3$ and $4$ modes of oscillation. We found that the $f$-mode frequencies of the $H$ and $\Delta$ EoSs were almost the same in the lower mass region, while we observed a substantial difference between them in the high-mass region. We also obtained an empirical relation for the EoSs considered. The various attributes obtained for our models showed close agreement with various observational constraints from pulsars and GW events.

Measurements of the binary black hole spin distribution from the growing catalog of gravitational-wave observations can help elucidate the astrophysical processes shaping the formation and evolution of these systems. Spin-orbit resonances are one process of interest, in which the component spin vectors and the orbital angular momentum align into a common plane and jointly precess about the total angular momentum of the system. These resonances, which occur preferentially in systems formed via isolated binary evolution with strong tidal effects, lead to excesses in the distribution of the azimuthal angle between the projections of the component spin vectors onto the orbital plane at $\phi_{12}=0,\pm\pi$. Previous analyses have demonstrated that this parameter is particularly difficult to constrain for individual binaries. In this work, we conduct the first hierarchical analysis modeling the population-level distribution of $\phi_{12}$ simultaneously with the other mass and spin parameters for simulated binary black hole populations to determine whether spin-orbit resonances can be reliably constrained. While we are unlikely to find definitive evidence for spin-orbit resonances with a population of the size expected by the end of the ongoing LIGO-Virgo-KAGRA fourth observing run, we correctly recover the various $\phi_{12}$ distributions we simulate within uncertainties. We find that we can place meaningful constraints on the relative excesses at $\phi_{12}=0,\pm\pi$, which encodes information about mass transfer in the formation of the binary. We can also distinguish between fully isotropic spin angle distributions and those with features in the spin azimuth and tilt distributions. Thus, we show that population-level measurements of the $\phi_{12}$ distribution offer a reliable, novel way to probe binary formation channels, dynamics, and mass transfer with gravitational-wave observations.

The physical conditions of the earliest environment of high-mass star formation are currently poorly understood. To that end, we present observations of the carbon chain molecules HC$_5$N , CCS, and HC$_7$N in the 22-25 GHz band towards 12 high-mass 70 micron-dark clumps (SMDC) with the Jansky Very Large Array (VLA). We detect HC$_5$N and CCS towards 11 of these SMDC sources. We calculate column densities and abundances relative to H$_2$ for HC$_5$N and CCS. We do not find any clear HC$_7$N detections in the 11 sources individually, but by stacking the HC$_7$N spectra, we do detect HC$_7$N on average in these sources. We also calculate the ratio of the column densities of HC$_5$N to HC$_7$N using the stacked spectra of both species. We compare our measured abundances of HC$_5$N and our measured ratio of HC$_5$N to HC$_7$N to the UMIST dark cloud chemistry models to constrain an age for the gas assuming a fixed volume density and temperature. The chemical models favor a chemical evolutionary age less than 1 Myr at densities of n(H2) = 2 x 10$^4$ cm$^{-3}$. The consistent carbon-chain detections and young model-derived ages support the conclusion that these 11 70 micron-dark clumps lack high mass protostars because they are young and not because they are inefficient and incapable of high mass star formation.

Magnetic reconnection at small spatial scales is a fundamental driver of energy release and plasma dynamics in the lower solar atmosphere. We present novel observations of a brightening in an active region, captured in high-resolution data from the Daniel K. Inouye Solar Telescope (DKIST) using the Visible Broadband Imager (VBI) and the Visible Spectro-Polarimeter (ViSP). The event exhibits Ellerman bomb-like morphology in the H$\beta$ filter, associated with flux cancellation between a small negative polarity patch adjacent to opposite-polarity plage. Additionally, it displays a distinct annular emission pattern in Ca II K, hot jet-like structures containing Alfvénic plasma flows, and cooler surges. We employ multi-line, non-local thermodynamic equilibrium (non-LTE) inversions of the spectropolarimetric data to infer the stratification of the physical parameters of the atmosphere. Furthermore, we use the photospheric vector magnetogram inferred from the ViSP spectra as a boundary condition for nonlinear force-free field extrapolations, revealing the three-dimensional distribution of squashing factors. We find significant enhancements in temperature, velocity, and microturbulence confined to the upper photosphere and low chromosphere. Our findings provide observational evidence of low-altitude magnetic reconnection along quasi-separatrix layers in a compact fan-spine-type configuration, highlighting the complex interplay between magnetic topology, energy release, and plasma flows. Finally, we discuss the potential role of nonthermal particles in the distinct emissions at different wavelengths.

We compare multiple foreground-cleaning pipelines for estimating the tensor-to-scalar ratio, $r$, using simulated maps of the planned CMB-S4 experiment within the context of the South Pole Deep Patch. To evaluate robustness, we analyze bias and uncertainty on $r$ across various foreground suites using map-based simulations. The foreground-cleaning methods include: a parametric maximum likelihood approach applied to auto- and cross-power spectra between frequency maps; a map-based parametric maximum-likelihood method; and a harmonic-space internal linear combination using frequency maps. We summarize the conceptual basis of each method to highlight their similarities and differences. To better probe the impact of foreground residuals, we implement an iterative internal delensing step, leveraging a map-based pipeline to generate a lensing $B$-mode template from the Large Aperture Telescope frequency maps. Our results show that the performance of the three approaches is comparable for simple and intermediate-complexity foregrounds, with $\sigma(r)$ ranging from 3 to 5 $\times 10^{-4}$. However, biases at the $1-2\sigma$ level appear when analyzing more complex forms of foreground emission. By extending the baseline pipelines to marginalize over foreground residuals, we demonstrate that contamination can be reduced to within statistical uncertainties, albeit with a pipeline-dependent impact on $\sigma(r)$, which translates to a detection significance between 2 and 4$\sigma$ for an input value of $r = 0.003$. These findings suggest varying levels of maturity among the tested pipelines, with the auto- and cross-spectra-based approach demonstrating the best stability and overall performance. Moreover, given the extremely low noise levels, mutual validation of independent foreground-cleaning pipelines is essential to ensure the robustness of any potential detection.

We have considered a phenomenologically motivated model in which galaxies are quenched when the energy output of the central black hole exceeds a hundred times the gravitational binding energy of the baryons in the host halo. The model reproduces the mass functions of star-forming and quiescent galaxies at 0<z<2.5 and the quenching boundary on a $\Sigma_1$-stellar mass diagram. The quenching boundary arises because of the colour-morphology relation. The stellar surface density $\Sigma_1$ in the central kiloparsec is a morphological indicator. Galaxies becomes redder as $\Sigma_1$ increases until they cross the quenching boundary and enter the passive population. Mergers drive the growth of supermassive black holes and the morphological evolution that accompany the migration to the red sequence. That is the origin of the population of high-mass passive galaxies. At lower masses, passive galaxies are mainly satellites that ceased to form stars because of environmental effects.

Quadratic gravity is a fourth-order (in derivatives) theory that can serve as an attractive upgrade to the standard description of gravity provided by General Relativity, thanks to its renormalizability and its built-in description of primordial inflation. We bring quadratic gravity into a second-order form by introducing an auxiliary tensor field and we consider the primordial tensor fluctuations (gravitational waves) in the theory around a Friedmann-Lemaître-Robertson-Walker background. After a canonical quantization of the perturbations, we calculate the tensor power spectrum in quasi de Sitter spacetime. We find that the spectral index $n_t$ and the amplitude $A_t$ of the tensor power spectrum are both suppressed by the factor $(1 + 2{\bf H}^2_*/m_\text{gh}^2)^{-1}$, where ${\bf H}_*$ is the Hubble rate at horizon exit and $m_\text{gh}$ is the mass of the spin-two ghost. This restores the slow-roll consistency condition familiar from single-field inflation models, where the tensor-to-scalar ratio $r$ is equal to $-8n_t$ in the lowest nontrivial order in the slow-roll approximation. We also discuss the well-known issue of the ghost problem in fourth-order theories and how it pertains to the results at hand.

We study the formation of primordial black holes (PBHs) and stochastic gravitational waves background (SGWB) produced by the supercooled radion phase transition (PT) in warped extra-dimension models solving the gauge hierarchy problem. We first determine how the SGWB and the produced PBH mass and abundance depend on the warped model's infrared energy scale $\rho$, and the number of holographic colors $N$. With this finding, we recast on the plane $\{\rho, N\}$ the current SGWB and PBH constraints, as well as the expected parameter reaches of GW detectors, as LISA and ET, and the gravitational lensing ones, such as NGRST. On the same plane, we also map the collider bounds on massive graviton production, and cosmological bounds on the radion phenomenology. We find that, for $N \sim 10-50$, the considered PT predicts a PBH population mass in the range $M_{\rm PBH}\sim(10^{-1} - 10^{-25}) M_{\odot}$ for $\rho \sim (10^{-4} - 10^{8})\textrm{ TeV}$. In the range $\rho \simeq (0.05 - 0.5)$ GeV, it can explain the recent SGWB hint at nHz frequencies and generate PBH binaries with mass $M_{\rm PBH}\sim(0.1 - 1 ) M_\odot$ detectable at LISA and ET. The experimentally allowed mass region where PBHs can account for the whole dark matter abundance, and are produced with a tuning $\lesssim 10^{-4}$, corresponds to $10$ TeV $\lesssim \rho\lesssim$ $10^4$ TeV. These PBHs can compensate the lack of natural candidates for dark matter in warped extra dimensional models. Such a region represents a great science case where forthcoming and future colliders like HE-LHC and FCC-hh, gravitational-wave observatories and other PBHs probes play a key complementary role.

In this work we investigate the chemical and kinetic nonequilibrium dynamics of the Higgs boson during the primordial Universe QGP (quark-gluon plasma) epoch $130\mathrm{\,GeV}>T>10\mathrm{\,GeV}$. We show that the Higgs bosons is always out of chemical abundance equilibrium with a fugacity $\Upsilon_h = 0.69$ due to virtual decay channels. Additionally, Higgs momentum distribution is found to be ``cold'' for $T<40$\,GeV, since the scattering rate drops below the production rate.

We introduce a computational framework, Bayesian Evidence calculation fOr Model Selection (BEOMS) to evaluate multiple Bayesian model selection methods in the context of determining the equation of state (EOS) for cold neutron star (NS), focusing on their performance with current and next-generation gravitational wave (GW) observatories. We conduct a systematic comparison of various EOS models by using posterior distributions obtained from EOS-agnostic Bayesian inference of binary parameters applied to GWs from a population of binary neutron star (BNS) mergers. The cumulative evidence for each model is calculated in a multi-dimensional parameter space characterized by neutron star masses and tidal deformabilities. Our findings indicate that Bayesian model selection is most effective when performed in the two-dimensional subspace of component mass and tidal deformability, requiring fewer events to distinguish between EOS models with high confidence. Furthermore, we establish a relationship between the precision of tidal deformability measurements and the accuracy of model selection, taking into account the evolving sensitivities of current and planned GW observatories. BEOMS offers computational efficiency and can be adapted to execute model selection for gravitational wave data from other sources.

The measurement of spin-precession and orbital eccentricity in gravitational-wave (GW) signals is a key priority in GW astronomy, as these effects not only provide insights into the astrophysical formation and evolution of compact binaries but also, if neglected, could introduce significant biases in parameter estimation, searches, and tests of General Relativity. Despite the growing potential of upcoming LIGO-Virgo-KAGRA observing runs and future detectors to measure eccentric-precessing signals, accurately and efficiently modeling them remains a challenge. In this work, we present pyEFPE, a frequency-domain post-Newtonian (PN) waveform model for the inspiral of precessing-eccentric compact binaries. pyEFPE improves upon previous models by introducing analytical expressions for the Fourier mode amplitudes, enhancing the numerical stability of the multiple scale analysis framework, and adding recently derived PN corrections, critical to accurately describe signals in GW detectors. Additionally, we simplify the numerical implementation and introduce a scheme to interpolate the amplitudes, achieving a speedup of up to ~O(20) in the waveform computations, making the model practical for data analysis applications. We thoroughly validate pyEFPE by comparing it to other waveform models in the quasi-circular and eccentric-spin-aligned limits, finding good agreement. Additionally, we demonstrate pyEFPE's capability to analyze simulated GW events, accurately recovering the parameters of signals described by both pyEFPE and IMRPhenomXP. While pyEFPE still lacks important physical effects, such as higher-order PN corrections, higher-order modes, mode asymmetries, tidal interactions or the merger-ringdown phase, it represents a significant step towards more complete waveform models, offering a flexible and efficient framework that can be extended in future work to incorporate these effects.

Differentially rotating scalarized neutron stars, mimickers of binary merger remnants, can possess an enormous angular momentum larger than what could possibly be sustained in a neutron star in general relativity by about one order of magnitude. A natural question to ask is whether these solutions are stable and thus can realize in a binary coalescence. With this motivation in mind, we examine the criterion of dynamical stability against axisymmetric perturbations for these ultra-rotators by numerically tracking their nonlinear evolution in an axisymmetric setup. We demonstrate that the turning-point criterion still serves as a sufficient condition for asymmetric (in)stability. Our findings open an interesting question of whether the merger of two scalarized neutron stars can produce (possibly short-lived) ultra-highly rotating merger remnants.

In Paper I, we introduced an alternative second-generation time-delay interferometry (TDI) configuration, hybrid Relay, designed to minimize null frequencies and enhance data analysis for massive binary black hole (MBBH). In Paper II, we further improved its performance in noise characterization by replacing its null stream with a specialized stable channel, $C^{12}_3$. In this work, we propose a novel TDI configuration, labeled PD4L, which features minimal null frequencies and a reduced time span. Unlike the hybrid Relay or the second-generation Michelson, which require a maximum delay of $7L$ (where $L$ is the ranging time of interferometric arm), the PD4L synthesizes data only within $3L$ delay. This shorter time span brings several advantages: 1) reducing margins at boundaries of data segments, 2) mitigating frequency aliasing in the high frequency band, and 3) shortening the tail at the end of a signal. To assess its effectiveness in data analysis, we perform parameter inference for a rapidly chirping gravitational wave signal from a MBBH. As a more compact TDI structure, PD4L achieves more accurate parameters estimation in the frequency-domain compared to the hybrid Relay. Additionally, PD4L's null stream exhibits minimal null frequencies, identical to its science channels, while maintaining a more stable noise spectrum than the $C^{12}_3$. We further evaluate its capability in noise characterization. The results demonstrate that although the stability of noise spectra in science channels is slightly lower compared to that of hybrid Relay, PD4L can still reliably infer noise parameters for data durations of up to four months. These investigations and comparisons suggest that PD4L is a promising TDI scheme, particularly for the higher frequency band.

We introduce and describe $\tt GrayHawk$, a publicly available Mathematica-based tool designed for the efficient computation of gray-body factors for spherically symmetric and asymptotically flat black holes. This program provides users with a rapid and reliable means to compute gray-body factors for massless fields with spin \(s = 0, 1/2, 1, 2\) in modes specified by the angular quantum number \(l\), given a black hole metric and the associated parameter values. $\tt GrayHawk$ is preloaded with seven different black hole metrics, offering immediate applicability to a variety of theoretical models. Additionally, its modular structure allows users to extend its functionality easily by incorporating alternative metrics or configurations. This versatility makes $\tt GrayHawk$ a powerful and adaptable resource for researchers studying black hole physics and Hawking radiation. The codes described in this work are publicly available at this https URL.

Massive Boson Stars are self-gravitating configurations of self-interacting scalar fields. The equation of state of massive boson stars and their masses, radii, modeled by a self-interacting scalar field with potential of the form $V(\phi) = \frac{1}{2}m^2|\phi|^2 + \frac{1}{4}\lambda |\phi|^4$ are known to follow scaling relations. The non-radial fundamental oscillations of such massive BSs have been studied only for a few select model parameters so far. In this work, we demonstrate for the first time that the $f$-mode characteristics also follow a scaling in the strong interaction limit ($\lambda \gg m^2/M_{Pl}^2$). This opens up the outstanding prospect of studying the $f$-modes of massive BSs throughout the scalar DM parameter space. We study the implications of this finding by carrying out a detailed study of massive BS $f$-modes in a separate work. Here, having introduced this scaling, we use it to compare boson star oscillations with the neutron star and black hole quasinormal modes, thus providing a smoking gun for the distinguishability of BSs using gravitational waves.

Boson Stars (BSs) are macroscopic self-gravitating configurations made of complex scalar fields. These exotic compact objects (ECO) would manifest as dark Boson stars and can contribute to a certain fraction of the dark matter (DM) in the universe. In this work, we study the fundamental non-radial oscillations ($f$-modes) of massive BSs and the associated gravitational wave (GW) emission. We consider massive scalar BSs having the potential of the form $V(\phi) = \frac{1}{2}m^2|\phi|^2 + \frac{1}{4}\lambda |\phi|^4$, restricting to the strong-coupling regime ($\lambda \gg m^2/M_{Pl}^2$) where solutions resembling fermionic stars are known to exist. We first review the available parameter space for scalar DM that can form massive BSs and enlist various constraints. We fit and provide simple analytical relations connecting various macroscopic observables for BSs, which can be directly incorporated into future studies of massive BSs throughout the strong coupling regime without requiring any numerical computation. We then solve for the non-radial $l=2$ fundamental quasinormal modes ($f$-modes) for massive BSs. Scaling relations for $f$-mode equations have been reported in another work. Using these, we perform a complete study of these oscillations spanning the entire available parameter space of massive BSs and provide analytical fits for the $f$-mode characteristics. We further study the universal relations for BSs and reveal the parameter space that is sensitive to the current and future planned GW detectors. We find that different parts of the parameters space can, in principle, be probed by the LISA, LIGO, and NEMO detectors. Finally, we briefly discuss the detectability of $f$-modes from BSs that have not been explored before.

In this work we study the possibility to detect the gravitational waves generated by a secluded self-interacting dark sector. ``Secluded'' means that the dark sector has almost no portal to the visible sector and thus its entropy is conserved by itself, and ``self-interacting'' means that dark matter in this model has a significant interaction to itself, making it consistent with the small-scale structure observations. A spontaneously broken $U(1)'$ is introduced for the interactions in the dark sector, and nearly massless dark radiation is also introduced to avoid the over-closure problem. Through a parameter space scan, we find that this model is highly constrained by the current observed effective number of neutrinos ($N_{\text{eff}}$) and the large-scale structure observable Lyman-$\alpha$. Combined together, these two constraints make such a secluded self-interacting dark sector almost impossible to generate gravitational waves accessible at future projects like SKA or LISA.

In this work, we explore two classes of density dependent relativistic mean-field models, their predictions of proton fractions at high densities and neutron star structure. We have used a metamodelling approach to these relativistic density functionals. We have generated a large ensemble of models with these classes and then applied constraints from theoretical and experimental nuclear physics and astrophysical observations. We find that both models produce similar equations of state and neutron star mass-radius sequences. But, their underlying compositions, denoted by the proton fraction in this case, are vastly different. This reinstates previous findings that information on composition gets masqueraded in $\beta$-equilibrium. Additional observations of non-equilibrium phenomena are necessary to pin it down.

The Breakthrough Starshot project aims to send a tiny 2 gram spacecraft to Proxima Centauri propelled by a light sail and powerful Earth-based lasers. We provide two derivations of the laser energy required to propel the spacecraft and give the reader the opportunity to decide which one is correct before providing the answer. In the second part of this paper we point out that one of the formulae in Einstein's amazing 1905 paper is correct only in certain limits, but Einstein fails to mention that. This has caused some confusion in the Breakthrough Starshot literature.