Papers for Monday, Jun 10 2024

Dark matter makes up approximately 85% of total matter in our universe, yet it has never been directly observed in any laboratory on Earth. The origin of dark matter is one of the most important questions in contemporary physics, and a convincing detection of dark matter would be a Nobel-Prize-level breakthrough in fundamental science. The ABRACADABRA experiment was specifically designed to search for dark matter. Although it has not yet made a discovery, ABRACADABRA has produced several dark matter search results widely endorsed by the physics community. The experiment generates ultra-long time-series data at a rate of 10 million samples per second, where the dark matter signal would manifest itself as a sinusoidal oscillation mode within the ultra-long time series. In this paper, we present the TIDMAD -- a comprehensive data release from the ABRACADABRA experiment including three key components: an ultra-long time series dataset divided into training, validation, and science subsets; a carefully-designed denoising score for direct model benchmarking; and a complete analysis framework which produces a community-standard dark matter search result suitable for publication as a physics paper. This data release enables core AI algorithms to extract the signal and produce real physics results thereby advancing fundamental science. The data downloading and associated analysis scripts are available at this https URL

The LIGO-Virgo-KAGRA (LVK) collaboration has recently made it possible for early warning alerts to be sent out, potentially before the end of the gravitational wave (GW) emission from a neutron star binary. If we get such alerts in this (the fourth) or the next observing run they may arrive up to tens of seconds before the merger, which is comparable to the slewing times of the Large Size Telescopes (designed to observe very high energy gamma rays): it would be therefore possible to point to the source right before it starts emitting an electromagnetic signal. This new mode of observation would allow us to detect the TeV component of prompt emission, which is currently poorly constrained and understood. There are many technical challenges to overcome before this can be realized: improving the synergy between gravitational observatories and telescopes, reducing operational latencies and, from the gravitational wave side, providing more information, such as real-time updates on early warning candidates and the probability distribution of the inclination angle. Although we may need to wait a few years -- in the worst case scenario, until the next generation of GW detectors is built -- before the first detection of this kind is made, implementing these improvements is a necessity.

Observations of nearby massive galaxies have revealed that they are older and richer in metals and magnesium than their low-mass counterparts. In particular, the overabundance of magnesium compared to iron, [Mg/Fe], is interpreted to reflect the short star formation history that the current massive galaxies underwent early in the Universe. We present a systematic revision of the [Mg/Fe] - velocity dispersion ($\sigma$) relation based on stacked spectra of early-type galaxies with a high signal-to-noise ratio from the Sloan Digital Sky Survey (SDSS). Using the penalized pixel-fitting (pPXF) method of Cappellari & Emsellem 2004 and the Vazdekis et al. 2015 MILES single stellar population (SSP) models, we fit a wide optical wavelength range to measure the net $\alpha$-abundance. The combination of pPXF and $\alpha$-enhanced MILES models incorrectly leads to an apparently decreasing trend of [$\alpha$/Fe] with velocity dispersion. We interpret this result as a consequence of variations in the individual abundances of the different $\alpha$-elements. This warrants caution for a naïve use of full spectral fitting algorithms paired with stellar population models that do not take individual elemental abundance variations into account, especially when deriving averaged quantities such as the mean [$\alpha$/Fe] of a stellar population. In addition, and based on line-strength measurements, we quantify the impact of a non-universal initial mass function on the recovered abundance pattern of galaxies. In particular, we find that a simultaneous fit of the slope of the initial mass function and the [Mg/Fe] results in a shallower [Mg/Fe]-$\sigma$ relation. Therefore, our results suggest that star formation in massive galaxies lasted longer than what has been reported previously, although it still occurred significantly faster than in the solar neighbourhood.

We present lenscat, a public and community-contributed catalog of strong gravitational lenses found by electromagnetic surveys. The main objective of lenscat is to compile a simple, easy-to-access catalog that can be used in a variety of lensing studies, such as facilitating the search for the host galaxy of a candidate strongly lensed transient event. We also provide a python package to interact with tools commonly used by the community. This allows end users both with and without lensing expertise to obtain a list of known strong lenses within a given search area, and to also rank them by their respective searched probabilities. Here, we exemplify this by crossmatching the gravitational wave joint sky localization region of an interesting pair of events GW170104-GW170814. Other examples with short gamma-ray bursts are given. Thanks to the open and simple infrastructure of lenscat, members of the lensing community can directly add newly found lenses from their own studies to help create a long-lasting catalog that is as exhaustive and accessible as possible.

The circumgalactic medium (CGM) serves as a baryon reservoir that connects galaxies to the intergalactic medium and fuels star formation. The spatial distribution of the metal-enriched cool CGM has not yet been directly revealed at cosmic noon (z~2-4), as bright emission lines at these redshifts are not covered by optical integral field units. To remedy this situation, we aim for the first-ever detections and exploration of extended SiII* emission (low-ionization state, LIS), referred to as ``SiII* halos'', at redshifts ranging from z=2 to 4 as a means to trace the metal-enriched cool CGM. We use a sample of 39 galaxies with systemic redshifts of z=2.1-3.9 measured with the [CIII] doublet in the MUSE Hubble Ultra Deep Field catalog, which contains integration times spanning from ~30 to 140 hours. We search for extended SiII*1265, 1309, 1533 emission (fluorescent lines) around individual galaxies. We also stack a subsample of 14 UV-bright galaxies. We report five individual detections of SiII*1533 halos. We also confirm the presence of SiII*1533 halos in stacks for the subsample containing UV-bright sources. The other lines do not show secure detections of extended emission in either individual or stacking analyses. These detections may imply that the presence of metal-enriched CGM is a common characteristic for UV-bright galaxies. To investigate whether the origin of SiII* is continuum pumping as suggested in previous studies, we check the consistency of the equivalent width (EW) of SiII* emission and the EW of SiII absorption for the individual halo object with the most reliable detection. We confirm the equivalence, suggesting that photon conservation works for this object and pointing toward continuum pumping as the source of SiII*. We also investigate SiII* lines in a RAMSES-RT zoom-in simulation including continuum pumping and find ubiquitous presence of extended halos.

Cosmic ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star formation in galaxies, and escape from active galactic nuclei to heat the cooling cores of galaxy clusters. The feedback strength of CRs depends on their coupling to the background plasma and, as such, on the effective CR transport speed. Traditionally, this has been hypothesized to depend on the balance between wave growth of CR-driven instabilities and their damping. Here, we study the physics of CR-driven instabilities from first principles, starting from a gyrotropic distribution of CR ions that stream along a background magnetic field. We develop a theory of the underlying processes that organize the particles' orbits and in particular their gyrophases, which provides an intuitive physical picture of (i) wave growth as the CR gyrophases start to bunch up lopsidedly towards the local wave magnetic field, (ii) instability saturation as a result of CRs overtaking the wave and damping its amplitude without isotropizing CRs in the wave frame, and (iii) CR back-reaction onto the unstable plasma waves as the CR gyrophases follow a pendulum motion around the wave magnetic field. Using our novel fluid-particle-in-cell code fluid-SHARP, we validate our theory on the evolution and excitation of individual unstable modes, such as forward and backward propagating Alfvén and whistler waves. We show that these kinetic simulations support our theoretical considerations, thus potentially foreshadowing a fundamental revision of the theory of CR transport in galaxies and galaxy clusters.

Internal gravity waves (IGWs) are likely to cause mixing in stellar interiors. Studies show that the mixing by these waves changes drastically across age and mass (Varghese et al. 2023, arXiv:2211.06432). Here, we study the effect of rotation on this wave mixing by considering a 7 M$_{\odot}$ model at ZAMS and midMS. We compare the mixing profiles at a range of rotation rates ($1\times 10^{-5}$, $2\times 10^{-5}$, $3\times 10^{-5}$, $4\times 10^{-5}$ and $1\times 10^{-4}$ rad.s$^{-1}$) and observe that the mixing decreases with decreasing Rossby number. This can be attributed to the effect of rotation on convection which influences the amplitude with which the waves are excited near the convective-radiative interface.

Software is crucial for the advancement of astronomy especially in the context of rapidly growing datasets that increasingly require algorithm and pipeline development to process the data and produce results. However, software has not always been consistently cited, despite its importance to strengthen support for software development. To encourage, streamline, and standardize the process of citing software in academic work such as publications we introduce 'The Software Citation Station': a publicly available website and tool to quickly find or add software citations

The accurate determination of the true redshift distributions in tomographic bins is critical for cosmological constraints from photometric surveys. The proposed redshift self-calibration method, which utilizes the photometric galaxy clustering alone, is highly convenient and avoids the challenges from incomplete or unrepresentative spectroscopic samples in external calibration. However, the imperfection of the theoretical approximation on broad bins as well as the flaw of the previous algorithm risk the accuracy and application of the method. In this paper, we propose the improved self-calibration algorithm that incorporates novel update rules, which effectively accounts for heteroskedastic weights and noisy data with negative values. The improved algorithm greatly expands the application range of self-calibration method and accurately reconstructs the redshift distributions for various mock data. Using the luminous red galaxy (LRG) sample of the Dark Energy Spectroscopic Instrument (DESI) survey, we find that the reconstructed results are comparable to the state-of-the-art external calibration. This suggests the exciting prospect of using photometric galaxy clustering to reconstruct redshift distributions in the cosmological analysis of survey data.

Pixelated dark energy is a string theory scenario with a quantum mechanically stable cosmological constant. The number of pixels that make up the universe slowly increases, manifesting as a time-dependent source of dark energy. DESI has recently reported evidence for dynamical dark energy that fits within this framework. In light of this, we perform the first cosmological analysis of the pixelated model. We find that the simplest model where the pixel growth rate is constant is unable to accommodate the data, providing a comparable fit to $\Lambda$CDM; but that models where the pixel growth rate is increasing and of order the Hubble constant today are compatible. Our analysis helps to clarify the features of UV constructions of dark energy necessary to accommodate the data.

Supermassive black hole binaries (SMBHBs) present us with exciting opportunities for multi-messenger science. These systems are thought to form naturally in galaxy mergers and therefore have the potential to produce electromagnetic (EM) radiation as well as gravitational waves (GWs) detectable with pulsar timing arrays (PTAs). Once GWs from individually resolved SMBHBs are detected, the identification of the host galaxy will be a major challenge due to the ambiguity in possible EM signatures and the poor localization capability of PTAs. In order to aid EM observations in choosing which sources to follow up, we attempt to quantify the number of plausible hosts in both realistic and idealistic scenarios. We outline a host galaxy identification pipeline that injects a single-source GW signal into a simulated PTA dataset, uses production-level techniques to recover the signal, quantifies the localization region and number of galaxies contained therein, and finally imposes cuts on the galaxies using the binary parameters estimated from the GW search. In an ideal case, we find that the 90% credible areas span 29 deg^2 to 241 deg^2, containing about 14 to 341 galaxies. After cuts, the number of galaxies remaining ranges from 22 at worst to 1 (the true host) at best. In a more realistic case, if the signal is sufficiently localized, the sky areas range from 287 deg^2 to 530 deg^2 and enclose about 285 to 1238 galaxies. After cuts, the number of galaxies is 397 at worst and 27 at best. While the signal-to-noise ratio is the primary determinant of the localization area of a given source, we find that the size of the area is also influenced by the proximity of nearby pulsars on the sky and the chirp mass of the source.

Stellar and AGN feedback primarily affect the formation and evolution of galaxies and the circumgalactic medium, leaving some imprint on larger scales. Based on the SIMBA hydrodynamical simulation suite, and using the full set of Minkowski functionals (MFs), this study systematically analyses the time evolution of the global geometry and topology of the gas temperature, pressure, density (total, HI and H$_2$), and metallicity fields between redshift $z=5$ and $z=0$. MFs show that small-scale astrophysical processes are persistent and manifest on larger, up to tens of Mpc scales, highlighting the specific morphological signatures of the relevant feedback mechanisms on such scales in the last $\sim12$~Gyr. In qualitative terms, one can establish a ranking that varies according to the field considered: stellar feedback mostly determines the morphology of the pressure and density fields, AGN jets are the first cause for the morphology of the temperature and metallicity fields, while X-ray heating and AGN winds play the second most important role in shaping the geometry and topology of all the gaseous fields but metallicity. Hence the cosmic evolution of the geometry and topology of fields characterising the thermodynamical and chemical properties of the cosmic web provides complementary larger-scale constraints to galaxy formation models.

The origin of our Galaxy's high-velocity clouds (HVCs) remains a mystery after many decades of effort. In this paper, we use the TNG50 simulation of the IllustrisTNG project to identify cool, dense clouds that match observations of Galactic HVCs. We track these clouds back in time to determine their origin. We find that only 17% of HVCs (by mass) can be tracked directly to the disk, and 21% to satellite accretion. The majority of HVCs (62%) arise from warm and hot circumgalactic gas that cools through thermal instability. They then obtain their anomalous velocities through interactions with the turbulent circumgalactic medium. At TNG50 resolution, we do not see evidence for HVCs forming out of very low metallicity intergalactic material. Instead, low metallicity HVCs are most likely associated with satellite accretion. These results suggest that Galactic HVCs are highly heterogeneous in their origin, and can provide insight into the physical processes that shape the circumgalactic medium such as disk outflows, satellite accretion, and thermal instabilities.

We present an analysis of 8 JWST Mid-Infrared Instrument 5.6 micron images with 5sigma depths of ~0.1uJy. We detect 2854 sources within our combined area of 18.4 sq.arcmin -- a >4x increase in source density over earlier IRAC channel 3 data. We compute the MIRI 5.6um number counts including an analysis of the field-to-field variation. Relative to earlier published MIRI 5.6micron counts, our counts have a more pronounced knee, at roughly 2\,$\mu$Jy. The location and amplitude of the counts at the knee are consistent with the Cowley et al. (2018) model predictions, although these models tend to overpredict the counts below the knee. In areas of overlap, 84% of the MIRI sources have a counterpart in the COSMOS2020 catalog. These MIRI sources have redshifts that are mostly in the z~0.5-2, with a tail out to z~5. They are predominantly moderate to low stellar masses $10^8-10^{10}$M$_{\odot}$) main sequence star-forming galaxies suggesting that with $\approx$2hr exposures, MIRI can reach well below $M^*$ at cosmic noon and reach higher mass systems out to z~5. Nearly 70% of the COSMOS2020 sources in areas of overlap now have a data point at 5.6micron (rest-frame near-IR at cosmic noon) which allows for more accurate stellar population parameter estimates. Finally, we discover 31 MIRI-bright sources not in COSMOS2020. A cross-match with IRAC channel 1 suggests that 10-20% of these are likely lower mass (M$_*\approx10^9$M$_{\odot}$), $z\sim1$ dusty galaxies. The rest (80--90%) are consistent with more massive, but still very dusty galaxies at z>3.

Thawing quintessence scalar field models with the various potential forms to explain the late-time cosmic acceleration are compared to the {\Lambda}CDM model in detail by analyzing cosmological parameters with a set of observational data including H(z), BAO, CMB, SNIa, BBN, and f(z){\sigma}8 at the background and the perturbation levels. At low redshifts for the thawing quintessence scalar field models, the growth rate of the cosmic structure is significant. By utilizing a standard Markov Chain Monte Carlo (MCMC) procedure based on the recent expansion and the growth observational data with the statistical values of the Akaike and the Bayesian information criteria, we discuss the consistency of the thawing quintessence scalar field models with the set of different potentials with the observational data. The main consequence of this work is that despite the various considered potential forms that are very popular in the literature, we should be looking for consistent potential forms with observational data. Keywords: Thawing Dark Energy, Large Scale Structure, Markov Chain Monte Carlo Method, Observational Constraints, Matter Perturbations.

We report observations of the atmospheric transmission spectrum of the sub-Neptune exoplanet GJ 3470 b taken using the Near-Infrared Camera (NIRCam) on JWST. Combined with two archival HST/WFC3 transit observations and fifteen archival Spitzer transit observations, we detect water, methane, sulfur dioxide, and carbon dioxide in the atmosphere of GJ 3470 b, each with a significance of >3-sigma. GJ 3470 b is the lowest mass -- and coldest -- exoplanet known to show a substantial sulfur dioxide feature in its spectrum, at $M_{p}$=11.2${\,{\rm M}_{\oplus}}$ and $T_{eq}$=600$\,$K. This indicates disequilibrium photochemistry drives sulfur dioxide production in exoplanet atmospheres over a wider range of masses and temperatures than has been reported or expected. The water, carbon dioxide, and sulfur dioxide abundances we measure indicate an atmospheric metallicity of approximately $100\times$ Solar. We see further evidence for disequilibrium chemistry in our inferred methane abundance, which is significantly lower than expected from equilibrium models consistent with our measured water and carbon dioxide abundances.

Observations of tidal disruption events (TDEs) show signs of Nitrogen enrichment reminiscent of other astrophysical sources such as active galactic nuclei (AGN) and star-forming galaxies. Given that TDEs probe the gas from a single star, it is possible to test if the observed enrichment is consistent with expectations from the CNO cycle by looking at the observed Nitrogen/Carbon (N/C) abundance ratios. Given that $\approx 20\%$ of solar mass stars (and an even larger fraction of more massive stars) live in close binaries, it is worthwhile to also consider what TDEs from stars influenced by binary evolution would look like. We show here that TDEs from stars stripped of their Hydrogen-rich (and Nitrogen-poor) envelopes through previous binary-induced mass loss can produce much higher observable N/C enhancements than even TDEs from massive stars. Additionally, we predict that the time-dependence of the N/C abundance ratio in the mass fallback rate of stripped stars will follow the inverse behavior of main-sequence stars, enabling a more accurate characterization of the disrupted star.

We re-examine the constraints provided by Herschel Space Observatory data regarding cold water emission from protoplanetary disks. Previous disk models that were used to interpret observed water emission concluded that oxygen (O/H) is depleted by at least 2 orders of magnitude if a standard, interstellar gas/dust mass ratio is assumed in the disk. In this work, we use model results from a recent disk parameter survey and show that most of the \textit{Herschel} constraints obtained for cold water (i.e. for transitions with an upper energy level $E_\mathrm{up}<200$ K, where the bulk of the disk water lies) can be explained with disk models adopting ISM-like oxygen elemental abundance (i.e. O/H=$3.2\times10^{-4}$) and the canonical gas/dust mass ratio of 100. We show that cold water vapor is mainly formed by photodesorption of water ice at the interface between the molecular layer and the midplane, and that its emission is relatively independent of the main disk properties like the disk gas mass and gas/dust mass ratio. We find that the abundance of water vapor in the outer disk is set by photoprocesses and depends on the (constant) vertical column density of water ice needed to attenuate the FUV photon flux, resulting in roughly constant emission for the parameters (gas mass, dust mass, disk radius) varied in our survey. Importantly, water line emission is found to be optically thick and hence sensitive to temperature more than abundance, possibly driving previous inferences of large scale oxygen depletion.

Numerous recent X-ray observations of coronal loops in both active regions (ARs) and solar flares have shown clearly that elemental abundances vary with time. Over the course of a flare, they have been found to move from coronal values towards photospheric values near the flare peak, before slowly returning to coronal values during the gradual phase. Coronal loop models typically assume that the elemental abundances are fixed, however. In this work, we introduce a time-variable abundance factor into the 0D ebtel++ code that models the changes due to chromospheric evaporation in order to understand how this affects coronal loop cooling. We find that for strong heating events ($\gtrsim$ 1 erg s$^{-1}$ cm$^{-3}$), the abundances quickly tend towards photospheric values. For smaller heating rates, the abundances fall somewhere between coronal and photospheric values, causing the loop to cool more quickly than the time-fixed photospheric cases (typical flare simulations) and more slowly than time-fixed coronal cases (typical AR simulations). This suggests heating rates in quiescent AR loops no larger than $\approx 0.1$ erg s$^{-1}$ cm$^{-3}$ to be consistent with recent measurements of abundance factors $f \gtrsim 2$.

We present the first results of three-dimensional (3D) numerical magnetohydrodynamic (MHD) simulations of the onset of magnetic reconnection via the tearing instability in dynamically thinning current sheets in the solar corona. In all our simulations, the onset of the non-linear tearing instability, which leads to the break-up of the thinning current sheet, does not occur until after the instability growth time becomes faster than the dynamic thinning time. Furthermore, as in previous 3D MHD simulations of static current sheets in the corona, for some parameters, the amount of magnetic shear is a fundamental switch-on parameter, which has consequences for coronal heating models. These results open up the possibility of using observable quantities of coronal current sheets to predict when they will break-up and release magnetic energy to power various energetic phenomena and/or heat the atmosphere.

The W. M. Keck Observatory is welcoming a new era where data reduction and archiving are tightly integrated into our observing model, under the auspices of the Observatory's Data Services Initiative (DSI) project. While previously the Keck Observatory Archive (KOA) archived minimally processed, raw science data the day after observing, Keck is transitioning to a model in which it archives both raw frames and reduced data in near real-time. These data will be made available to observers and collaborators immediately upon ingestion through a dedicated new interface that will support collaboration and sharing among teams, as well as stream data directly to personal computers without access to WMKO's internal networks. Both the raw and science-ready data products will be made publicly available upon the expiration of data protections.

The revolutionary discovery of dark energy and accelerating cosmic expansion was made with just 42 type Ia supernovae (SNe Ia) in 1999. Since then, large synoptic surveys, e.g., Dark Energy Survey (DES), have observed thousands more SNe Ia and the upcoming Rubin Legacy Survey of Space and Time (LSST) and Roman Space Telescope promise to deliver millions in the next decade. This unprecedented data volume can be used to test concordance cosmology. However, extracting a pure SN Ia sample with accurate redshifts for such a large dataset will be a challenge. Spectroscopic classification will not be possible for the vast majority of discovered objects, and only 25% will have spectroscopic redshifts. This thesis presents a series of observational and methodological studies designed to address the questions associated with this new era of photometric SN Ia cosmology. First, we present a machine learning (ML) method for SN photometric classification, SCONE. Photometric classification enables SNe with no spectroscopic information to be categorized, a critical step for cosmological analysis. SCONE achieves 99+% accuracy distinguishing simulated SNe Ia from non-Ia SNe, and is a part of DES, LSST, and Roman analysis pipelines. We also show that SCONE can classify 6 SN types with 75% accuracy on the night of initial discovery, comparable to results in the literature for full-phase SNe. Next, we study current methods for estimating SN Ia redshifts and propose an ML alternative that uses SN photometry alone to extract redshift information. Photo-zSNthesis is a host galaxy-independent redshift estimator accurate to within 2% across the redshift range of LSST, a first in the literature. Finally, we focus on ML robustness and demonstrate a general method for improving robustness that achieves new state-of-the-art results on astronomical object classification, wildlife identification, and tumor detection.

We present a complete census of candidate nuggets, i.e., dense galaxies likely formed by compaction with intense gas influx, within the volume-limited $z \sim 0$ REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. These nuggets span all evolutionary stages and 3 orders of magnitude in stellar mass ($M_{*} \sim 10^{8} M_\odot$ to $10^{11} M_\odot$) from the dwarf to the giant regime. We develop selection criteria for our $z\sim0$ nugget candidates based on structure and introduce the use of environmental criteria to eliminate nugget-like objects with suspected non-compaction origins. The resulting $z\sim0$ nuggets follow expectations with respect to structure (i.e., density, size), population frequency, and likely origins. We show that the properties of our nugget census are consistent with permanent quenching above the gas-richness threshold scale (halo mass $M_{halo} \sim 10^{11.4} M_\odot$), cyclic temporary quenching below the threshold scale, and feedback from active galactic nuclei (AGN) assisting in permanent quenching. As predicted in simulations, most nuggets quench within the halo mass range $M_{halo} \sim 10^{11.45} M_\odot$ to $10^{11.9} M_\odot$. We find $\sim 0.29$ dex scatter around the star-forming main sequence for candidate blue nuggets below the threshold scale, which is consistent with temporary quenching as seen in simulations. A transitional population of green nuggets appears above the threshold scale. AGN also become more common in nuggets above this scale, and we see a likely AGN excess in nuggets vs. comparably selected non-nuggets. Our results provide the first observational confirmation of the mass-dependent, AGN-mediated shift from cyclic quenching to halo quenching in nuggets.

I conducted a new search for dispersed radio pulses from the X-ray pulsar PSR J0537$-$6910 in the Large Magellanic Cloud in a long (11.6 hr) archival 1.4 GHz Parkes search observation. I searched dispersion measures (DMs) between 0 and 10000 pc cm$^{-3}$ and detected 49 pulses with a signal-to-noise ratio (S/N) greater than 7 at a wide range of DMs using the HEIMDALL and FETCH pulse detection and classification packages. All of the pulses were weak, with none having a S/N above 8.5. There was a significant excess of pulses observed in the DM range of the known pulsar population in the LMC, suggesting that these pulses may originate from LMC pulsars. Three repeat pulses, each having widths $\lesssim 1$ ms, were detected in a single DM trial of 103.412 pc cm$^{-3}$, which is in the LMC DM range. This is unlikely to occur by chance in a single DM trial in this search at the (marginally significant) 4.3$\sigma$ level. It remains unclear whether any of the detected pulses in the sample are from PSR J0537$-$6910 itself.

Studying transient phenomena, such as individual pulses from pulsars, has garnered considerable attention in the era of astronomical big data. Of specific interest to this study are Rotating Radio Transients (RRATs), nulling, and intermittent pulsars. This study introduces a new algorithm named LuNfit, tailored to correct the selection biases originating from the telescope and detection pipelines. Ultimately LuNfit estimates the intrinsic luminosity distribution and nulling fraction of the single pulses emitted by pulsars. LuNfit relies on Bayesian nested sampling so that the parameter space can be fully explored. Bayesian nested sampling also provides the additional benefit of simplifying model comparisons through the Bayes ratio. The robustness of LuNfit is shown through simulations and applying LuNfit onto pulsars with known nulling fractions. LuNfit is then applied to three RRATs, J0012+5431, J1538+1523, and J2355+1523, extracting their intrinsic luminosity distribution and burst rates. We find that their nulling fraction is 0.4(2), 0.749(5) and 0.995(2) respectively. We further find that a log-normal distribution likely describes the single pulse luminosity distribution of J0012+5431 and J1538+1523, while the Bayes ratio for J2355+1523 slightly favors an exponential distribution. We show the conventional method of correcting selection effects by "scaling up" the missed fraction of radio transients can be unreliable when the mean luminosity of the source is faint relative to the telescope sensitivity. Finally, we discuss the limitations of the current implementation of LuNfit while also delving into potential enhancements that would enable LuNfit to be applied to sources with complex pulse morphologies.

New JWST/NIRCam wide-field slitless spectroscopy provides redshifts for two z > 8 galaxies located behind the lensing cluster MACS J0416.1-2403. Both galaxies are strong [O iii]{\lambda}5007 emitters. For one galaxy, "Y1", the existing redshift z = 8.31, based on ALMA measurements of [O iii] 88 {\mu}m and [C ii] 157.7 {\mu}m lines, is confirmed. JWST/NIRCam images resolve this galaxy into three components of similar colors, and the whole system extends over ~3.4 kpc. The other galaxy, "JD", is at z = 8.34 instead of the previously claimed z = 9.28. It has a companion, "JD-N", at the same redshift with projected separation ~2.3 kpc. All objects are only moderately magnified and have intrinsic MUV ranging from -19.66 to -20.85 mag. Their eight-band NIRCam spectral energy distributions show that the galaxies are all very young with ages $\lesssim$11 Myr and stellar masses about 108 $M_{\odot}$. These infant galaxies are actively forming stars at rates of a few tens to a couple of hundred $M_{\odot} yr^{-1}$, but only one of them (JD) has a blue rest-frame UV slope. This slope indicates a high Lyman-continuum photon escape fraction that could contribute significantly to the cosmic hydrogen-reionizing background. The other two systems have much flatter slopes largely because their dust extinction is twice as high as JD's albeit only AV ~ 0.90 mag. The much lower indicated escape fractions show that even very young, actively star-forming galaxies can have negligible contribution to reionization when they quickly form dust throughout their bodies.

The Vera C. Rubin Observatory is a unique facility for survey astronomy that will soon be commissioned and begin operations. Crucial to many of its scientific goals is the achievement of sustained high image quality, limited only by the seeing at the site. This will be maintained through an Active Optics System (AOS) that controls optical element misalignments and corrects mirror figure error to minimize aberrations caused by both thermal and gravitational distortions. However, the large number of adjustment degrees of freedom available on the Rubin Observatory introduces a range of degeneracies, including many that are \textit{noise-induced} due to imperfect measurement of the wavefront errors. We present a structured methodology for identifying these degeneracies through an analysis of image noise level. We also present a novel scaling strategy based on Truncated Singular Value Decomposition (TSVD) that mitigates the degeneracy, and optimally distributes the adjustment over the available degrees of freedom. Our approach ensures the attainment of optimal image quality, while avoiding excursions around the noise-induced subspace of degeneracies, marking a significant improvement over the previous techniques adopted for Rubin, which were based on an Optimal Integral Controller (OIC). This new approach is likely to also yield significant benefits for all telescopes that incorporate large numbers of degrees of freedom of adjustment.

Mitigating the far sidelobes of a wide field-of-view telescope is one of the critical issues for polarization observation of the cosmic microwave background. Since even small reflections of stray light at the millimeter-wave absorbers inside the telescope may create nonnegligible far sidelobes, we have developed a method to measure the reflectance of millimeter-wave absorbers, including diffuse reflections. By applying the planar near-field measurement method to the absorbers, we have enabled two-dimensional diffuse-reflection measurements, in addition to characterizing specular reflection. We have measured the reflectance of five samples (TK RAM Large and Small Tiles and Eccosorb AN-72, HR-10, and LS-22) at two angles of incidence in the frequency range from 70 GHz to 110 GHz. Compared with conventional horn-to-horn measurements, we obtained a consistent specular reflectance with a higher precision, less affected by standing waves. We have demonstrated that the angular response and diffuse-to-specular reflectance ratio differ among various materials. The measurements also imply that some absorbers may affect the polarization direction when reflecting the incident waves.

In addition to being the most magnetic objects in the known universe, magnetars are the only objects observed to generate fast-radio-burst-like emissions. The formation mechanism of magnetars is still highly debated, and may potentially be probed with the magnetar velocity distribution. We carried out a 3-year-long astrometric campaign on Swift J1818.0-1607 -- the fastest-spinning magnetar, using the Very Long Baseline Array. After applying the phase-calibrating 1D interpolation strategy, we obtained a small proper motion of 8.5 $\mathrm{mas~yr^{-1}}$ magnitude, and a parallax of $0.12\pm0.02$ mas (uncertainties at $1\,\sigma$ confidence throughout the Letter) for Swift J1818.0-1607. The latter is the second magnetar parallax, and is among the smallest neutron star parallaxes ever determined. From the parallax, we derived the distance $9.4^{+2.0}_{-1.6}$ kpc, which locates Swift J1818.0-1607 at the far side of the Galactic central region. Combined with the distance, the small proper motion leads to a transverse peculiar velocity $v_\perp=48^{+50}_{-16}$ $\mathrm{km~s^{-1}}$ -- a new lower limit to magnetar $v_\perp$. Incorporating previous $v_\perp$ estimates of seven other magnetars, we acquired $v_\perp=149^{+132}_{-68}$ $\mathrm{km~s^{-1}}$ for the sample of astrometrically studied magnetars, corresponding to the three-dimensional space velocity $\sim190^{+168}_{-87}$ $\mathrm{km~s^{-1}}$, smaller than the average level of young pulsars. Additionally, we found that the magnetar velocity sample does not follow the unimodal young pulsar velocity distribution reported by Hobbs et al. at $>2\,\sigma$ confidence, while loosely agreeing with more recent bimodal young pulsar velocity distributions derived from relatively small samples of quality astrometric determinations.

We assess the usefulness of gradient-based samplers, such as the No-U-Turn Sampler (NUTS), by comparison with traditional Metropolis-Hastings algorithms, in tomographic $3 \times 2$ point analyses. Specifically, we use the DES Year 1 data and a simulated future LSST-like survey as representative examples of these studies, containing a significant number of nuisance parameters (20 and 32, respectively) that affect the performance of rejection-based samplers. To do so, we implement a differentiable forward model using JAX-COSMO (Campagne et al. 2023), and we use it to derive parameter constraints from both datasets using the NUTS algorithm as implemented in §4, and the Metropolis-Hastings algorithm as implemented in Cobaya (Lewis 2013). When quantified in terms of the number of effective number of samples taken per likelihood evaluation, we find a relative efficiency gain of $\mathcal{O}(10)$ in favour of NUTS. However, this efficiency is reduced to a factor $\sim 2$ when quantified in terms of computational time, since we find the cost of the gradient computation (needed by NUTS) relative to the likelihood to be $\sim 4.5$ times larger for both experiments. We validate these results making use of analytical multi-variate distributions (a multivariate Gaussian and a Rosenbrock distribution) with increasing dimensionality. Based on these results, we conclude that gradient-based samplers such as NUTS can be leveraged to sample high dimensional parameter spaces in Cosmology, although the efficiency improvement is relatively mild for moderate $(\mathcal{O}(50))$ dimension numbers, typical of tomographic large-scale structure analyses.

The kSZ effect has been detected at z<1 using various techniques and data sets. The ongoing and upcoming spectroscopic galaxy surveys such as DESI and PFS will push the detection beyond z = 1, and therefore map the baryon distribution at high redshifts. Such detection can be achieved by both the kSZ stacking and tomography methods. While the two methods are theoretically equivalent, they differ significantly in the probed physics and scales, and required data sets. Taking the combination of PFS and ACT as an example, we build mocks of kSZ and galaxies, quantify the kSZ detection S/N, and compare between the two methods. We segment the PFS galaxies into three redshift bins: 0.6 < z < 1.0, 1.0 < z < 1.6, and 1.6 < z < 2.4. For tomography method, our analysis reveals that the two higher redshift bins exhibit higher S/N, with values of 32 and 28, respectively, compared to the first redshift bin (S/N = 8). This is attributed to not only the increasing of electron density with redshifts, but also the larger survey volume and the reduced non-linearity, facilitating velocity reconstruction at higher redshifts. Therefore, the capability of the PFS survey to measure high redshift kSZ effect stands as a substantial advantage over other spectroscopic surveys at lower redshift. The S/N of kSZ stacking largely depends on the number of clusters/groups available from another photometric survey. But in general, its S/N is lower than that of kSZ tomography. Incorporating next-generation CMB surveys like CMB-S4, characterized by significantly reduced instrument noise and improved angular resolution, is expected to enhance tomographic detection by a factor of ten and stacking detection by five. This future high S/N detection holds the promise of not only providing precise constraints on the overall baryon abundance but also initiating a new insight into baryon distribution.

The newly updated \texttt{GIZMO} and \texttt{Simba} based simulation, \texttt{Simba-C}, with its new stellar feedback, chemical enrichment, and recalibrated AGN feedback, allows for a detailed study of the intragroup medium X-ray properties. We discuss the impact of various physical mechanisms, e.g. stellar and AGN feedback, and chemical enrichment, on the composition and the global scaling relations of nearby galaxy groups. We also study the evolution ($z=2$ to $0$) of the global properties for the $1\,\mathrm{keV}$ temperature groups. \texttt{Simba-C} shows improved consistent matching with the observations of all X-ray scaling relations compared to \texttt{Simba}. It is well known that AGN feedback has a significant influence on $L_{X,0.5-2.0}-T_{spec,corr}$, $S_{500/2500}-T_{spec,corr}$, and gas mass fractions, with our \texttt{Simba-C} results consistent with it. Our recalibrated AGN feedback strength also showed an additional improvement in gas entropy, which now aligns with CLoGS observations. The updated stellar feedback and chemical enrichment model is shown to play an important role in our understanding of the chemical abundance ratios and their evolution within galaxy groups. In particular, we find that \texttt{Simba-C} produces an increase in the amount of heavier elements (specifically Si and Fe) relative to O, compared to \texttt{Simba}.

Typical mechanisms to extract energies from a rotating black hole are the Blandford-Znajek process and the Penrose process. The Penrose process requires a special condition that is difficult to occur in common astrophysical situations. However, the magnetic Penrose process (MPP) does not require such a special condition, and can produce ultra-high energy cosmic rays. When neutrons decay near a rotating black hole, the MPP efficiency of the produced proton is maximized. The supermassive black hole in Sagittarius A* (Sgr A*) is likely to have a radiatively inefficient accretion flow that is hot enough to produce neutrons by nuclear reactions, which can be subsequently accelerated to high-energy by the MPP. We calculate the production rate of accelerated protons from the Sgr A* to estimated the gamma-ray flux at Earth produced by these accelerated protons and the flux of the accelerated protons themselves transported from Sgr A* to Earth. We find that these very high-energy gamma rays ($E_{\gamma}\gtrsim10\,\mathrm{TeV}$) amount to a significant fraction of the flux of the gamma-ray from the HESS J1745-290 and the central molecular zone around $100\,\mathrm{TeV}$. The accelerated proton flux, when the dimensionless spin parameter $a_{*}=0.5$ and the magnetic field strength in the vicinity of the black hole $B_{0}=100\,\mathrm{G}$, is about $1.6-4.1\%$ of the cosmic ray proton flux from KASCADE experiment at about $1\,\mathrm{PeV}$. Due to the finite decay time of neutrons which need to be transported from the accretion flow to the acceleration zone, our acceleration model can operate only around black holes with mass not much greater than $\sim10^8\,M_\odot$.

We use synthetic photometry from Gaia DR3 BP and RP spectra for a large selected sample of stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) to derive the magnitude of the Red Giant Branch (RGB) tip for these two galaxies in several passbands in various widely used optical photometric systems, including those of space missions that have not yet started operations. The RGB tip is estimated by fitting a well-motivated model to the RGB luminosity function (LF) within a fully Bayesian framework, allowing for a proper representation of the uncertainties of all the involved parameters and their correlations. Adopting the best available distance and interstellar extinction estimates we provide a calibration of the RGB tip as a standard candle for the following passbands: Johnson-Kron-Cousins I (mainly used for validation purposes), Hubble Space Telescope F814W, Sloan Digital Sky Survey i and z, PanSTARRS1 y, James Webb Space Telescope F090W, Nancy Grace Roman Space Telescope Z087, and Euclid I$_E$, with an accuracy of a few per cent, depending on the case. The trend of the absolute magnitude of the tip as a function of colour in the different passbands, beyond the range spanned by the LMC and SMC, as well as its dependency on age, is explored by means of theoretical models. These calibrations can be very helpful to obtain state-of-the-art RGB tip distance estimates to stellar systems in a very large range of distances directly from data in the natural photometric system of these surveys and/or missions, without recurring to photometric transformations. [abridged]

Recent hydrodynamical simulations of the late stages of supernova remnant (SNR) evolution have revealed that as they merge with the ambient medium, SNRs implode, leading to the formation of dense clouds in their center. While being highly chemically enriched by their host SNR, these clouds appear to have similar properties as giant molecular clouds, which are believed to be the main site of star formation. Here, we develop a simple model, in order to estimate the efficiency of the star formation that might be triggered by the implosion of SNRs. We separately consider two cases, cyclic star formation, maintained by the episodic driving of feedback from new generations of stars; and a single burst of star formation, triggered by a single explosion. We find that in the cyclic case, star formation is inefficient, with implosion-triggered star-formation contributing a few percent of the observed star-formation efficiency per free-fall timescale. In the single-burst case, higher star-formation efficiencies can be obtained. However, while the implosion-triggered process might not contribute much to the overall star-formation, due to the high chemical enrichment of the birth clouds, it can explain the formation of a significant fraction of metal-rich stars.

We present a method to mitigate the effects of fiber assignment incompleteness in two-point power spectrum and correlation function measurements from galaxy spectroscopic surveys, by truncating small angular scales from estimators. We derive the corresponding modified correlation function and power spectrum windows to account for the small angular scale truncation in the theory prediction. We validate this approach on simulations reproducing the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1) with and without fiber assignment. We show that we recover unbiased cosmological constraints using small angular scale truncated estimators from simulations with fiber assignment incompleteness, with respect to standard estimators from complete simulations. Additionally, we present an approach to remove the sensitivity of the fits to high $k$ modes in the theoretical power spectrum, by applying a transformation to the data vector and window matrix. We find that our method efficiently mitigates the effect of fiber assignment incompleteness in two-point correlation function and power spectrum measurements, at low computational cost and with little statistical loss.

We use the baryon acoustic oscillation (BAO) feature in the angular power spectrum (APS) of the 21cm line of neutral hydrogen (HI) to constrain cosmological parameters. As the BAO shift parameter can only constrain the product of the Hubble constant and the sound horizon $H_0r_s$, we combine our Fisher matrices with cosmic microwave background (CMB) Fisher matrices from the covariance of $Planck$ telescope to break this degeneracy. In particular, we find that the best constraints we can get with this method are on the Hubble parameter $h$, and the dark energy parameters $w_0$ and $w_a$. Assuming a noise level as for the BINGO telescope, we find $\sigma_h = 0.0055\;(0.8\%)$ in the $\Lambda$CDM model. For the $w$CDM model, we find $\sigma_h = 0.020\;(2.9\%)$ and $\sigma_{w_0} = 0.075\;(7.5\%)$. In the CPL parameterization, we find $\sigma_h = 0.029\;(4.4\%)$, $\sigma_{w_0} = 0.40\;(40\%)$, and $\sigma_{w_a} = 1.7$. Although these constraints improve those from $Planck$ alone, we observe the BINGO data will be more significant for the $w$CDM model. We also observe the constraints from the BAO only is not as strong as using the whole 21cm angular power spectrum, but it is less susceptible to systematic effects.

Spectral characterization of near-Earth asteroids (NEAs) has revealed a continuum of space-weathered states for the surfaces of S-complex NEAs, with Q-class NEAs, an S-complex subclass, most closely matching the un-weathered surfaces of ordinary chondrite meteorites. Dynamical calculations of the orbital evolution of S-complex NEAs revealed that Q-class NEAs tend to have close encounters with terrestrial planets, suggesting that planetary tides may play a role in refreshing NEA surfaces. However, the exact physical mechanism(s) that drive resurfacing through tidal encounters and the encounter distance at which these mechanisms are effective, has remained unclear. Through the lens of the upcoming (99942) Apophis encounter with Earth in 2029, we investigate the potential for surface mobilization through tidally-driven seismic shaking over short-timescales during encounter and subsequent surface slope evolution over longer-timescales driven by tumbling. We perform multi-scale numerical modeling and find that the 2029 encounter will induce short-term tidally-driven discrete seismic events that lead to high-frequency (greater than 0.1 Hz) surface accelerations that reach magnitudes similar to Apophis' gravity, and that may be detectable by modern seismometers. It is still unclear if the shaking we model translates to widespread particle mobilization and/or lofting. We also find there will be a significant change in Apophis' tumbling spin state that could lead to longer-term surface refreshing in response to tumbling-induced surface slope changes. We propose that through these mechanisms, space-weathered S-class asteroid surfaces may become refreshed through the exposure of unweathered underlying material. These results will be tested by the future exploration of Apophis by NASA's OSIRIS-APEX.

The $\beta$ Pictoris system is the closest known stellar system with directly detected gas giant planets, an edge-on circumstellar disc, and evidence of falling sublimating bodies and transiting exocomets. The inner planet, $\beta$ Pictoris c, has also been indirectly detected with radial velocity (RV) measurements. The star is a known $\delta$ Scuti pulsator, and the long-term stability of these pulsations opens up the possibility of indirectly detecting the gas giant planets through time delays of the pulsations due to a varying light travel time. We search for phase shifts in the $\delta$ Scuti pulsations consistent with the known planets $\beta$ Pictoris b and c and carry out an analysis of the stellar pulsations of $\beta$ Pictoris over a multi-year timescale. We used photometric data collected by the BRITE-Constellation, bRing, ASTEP, and TESS to derive a list of the strongest and most significant $\delta$ Scuti pulsations. We carried out an analysis with the open-source python package maelstrom to study the stability of the pulsation modes of $\beta$ Pictoris in order to determine the long-term trends in the observed pulsations. We did not detect the expected signal for $\beta$ Pictoris b or $\beta$ Pictoris c. The expected time delay is 6 seconds for $\beta$ Pictoris c and 24 seconds for $\beta$ Pictoris b. With simulations, we determined that the photometric noise in all the combined data sets cannot reach the sensitivity needed to detect the expected timing drifts. An analysis of the pulsational modes of $\beta$ Pictoris using maelstrom showed that the modes themselves drift on the timescale of a year, fundamentally limiting our ability to detect exoplanets around $\beta$ Pictoris via pulsation timing.

Stochastic backgrounds of gravitational waves from primordial first-order phase transitions are a key probe of physics beyond the Standard Model. They represent one of the best prospects for observing or constraining new physics with the LISA gravitational wave observatory. However, the large foreground population of galactic binaries in the same frequency range represents a challenge, and will hinder the recovery of a stochastic background. To test the recoverability of a stochastic gravitational wave background, we use the LISA Simulation Suite to generate data incorporating both a stochastic background and an annually modulated foreground modelling the galactic binary population, and the Bayesian analysis code Cobaya to attempt to recover the model parameters. By applying the Deviance Information Criterion to compare models with and without a stochastic background we place bounds on the detectability of gravitational waves from first-order phase transitions. By further comparing models with and without the annual modulation, we show that exploiting the modulation improves the goodness-of-fit and gives a modest improvement to the bounds on detectable models.

X-rays have significant impacts on cold, weakly ionized protoplanetary disks by increasing the ionization rate and driving chemical reactions. Stellar flares are explosions that emit intense X-rays and are the unique source of hard X-rays with an energy of $\gtrsim10$ keV in the protoplanetary disk systems. Hard X-rays should be carefully taken into account in models as they can reach the disk midplane as a result of scattering in the disk atmospheres. However, previous models are insufficient to predict the hard X-ray spectra because of the simplification in flare models. We develop a model of X-ray spectra of stellar flares based on observations and flare theories. The flare temperature and nonthermal electron emissions are modeled as functions of flare energy, which allows us to better predict the hard X-ray photon flux than before. Using our X-ray model, we conduct radiative transfer calculations to investigate the impact of flare hard X-rays on disk ionization, with a particular focus on the protoplanetary disk around a T Tauri star. We demonstrate that for a flare with an energy of $\geq 10^{33}$ erg, X-ray photons with $\gtrsim 10$ keV penetrate down to the midplane to increase the ionization rates more than galactic cosmic rays. We also find that the 10-year-averaged X-rays from multiple flares could certainly contribute to the ionization at the disk midplane. These results emphasize the importance of stellar flares on the disk evolution.

The circular polarization of the stochastic gravitational wave background (SGWB) is a key observable for characterising the origin of the signal detected by Pulsar Timing Array (PTA) collaborations. Both the astrophysical and the cosmological SGWB can have a sizeable amount of circular polarization, due to Poisson fluctuations in the source properties for the former, and to parity violating processes in the early universe for the latter. Its measurement is challenging since PTA are blind to the circular polarization monopole, forcing us to turn to anisotropies for detection. We study the sensitivity of current and future PTA datasets to circular polarization anisotropies, focusing on realistic modelling of intrinsic and kinematic anisotropies for astrophysical and cosmological scenarios respectively. Our results indicate that the expected level of circular polarization for the astrophysical SGWB should be within the reach of near future datasets, while for cosmological SGWB circular polarization is a viable target for more advanced SKA-type experiments.

Time-domain and multimessenger astronomy (TDAMM) involves the study of transient and time-variable phenomena across various wavelengths and messengers. The Astro2020 Decadal Survey has identified TDAMM as the top priority for NASA in this decade, emphasizing its crucial role in advancing our understanding of the universe and driving new discoveries in astrophysics. The TDAMM community has come together to provide further guidance to funding agencies, aiming to define a clear path toward optimizing scientific returns in this research domain. This encompasses not only astronomy but also fundamental physics, offering insights into gravity properties, the formation of heavy elements, the equation of state of dense matter, and quantum effects associated with extreme magnetic fields. Magnetars, neutron stars with the strongest magnetic fields known in the universe, play a critical role in this context. In this manuscript, we aim to underscore the significance of magnetars in TDAMM, highlighting the necessity of ensuring observational continuity, addressing current limitations, and outlining essential requirements to expand our knowledge in this field.

We analyzed the ALMA band 6 data for the outbursting massive protostar M17~MIR. The ALMA CO $J=2-1$ data reveals a collimated and bipolar north-south outflow from M17~MIR. The blue-shifted outflow exhibits four CO knots (N1 to N4) along the outflow axis, while the red-shifted outflow appears as a single knot (S1). The extremely high velocity (EHV) emissions of N1 and S1 are jet-like and contain sub-knots along the outflow axis. Assuming the nearest EHV sub-knots trace the ejecta from the accretion outbursts in the past decades, a tangential ejection velocity of $\sim421\,\mathrm{km\,s^{-1}}$ is derived for M17~MIR. Assuming the same velocity, the dynamical times of the multiple ejecta, traced by the four blue-shifted CO knots, range from 20 to 364 years. The four blue-shifted CO knots imply four clustered accretion outbursts with a duration of tens of years in the past few hundred years. The intervals between the four clustered accretion outbursts are also about tens of years. These properties of the four clustered accretion outbursts are in line with the disk gravitational instability and fragmentation model. The episodic accretion history of M17~MIR traced by episodic outflow suggests that a massive star can form from a lower-mass protostar via frequent episodic accretion events triggered by disk gravitational instability and fragmentation. The first detection of the knotty outflow from an outbursting massive protostar suggests that mass ejections accompanied with accretion events could serve as an effective diagnostic tool for the episodic accretion histories of massive protostars.

Classification of gamma-ray bursts (GRBs) has been a long-standing puzzle in high-energy astrophysics. Recent observations challenge the traditional short vs. long viewpoint, where long GRBs are thought to originate from the collapse of massive stars and short GRBs from compact binary mergers. Machine learning (ML) algorithms have been instrumental in addressing this problem, revealing five distinct GRB groups within the Swift/BAT light curve data, two of which are associated with kilonovae (KNe). We corroborate these five classes by extending this analysis to the Fermi/GBM data using unsupervised ML techniques. These five clusters are well separated in fluence-duration plane, hinting at a potential link between fluence, duration and complexities (or structures) in the light curves of GRBs. Further, we confirm two distinct classes of KN-associated GRBs. The presence of GRB 170817A in one of the two KNe-associated clusters lends evidence to the hypothesis that this class of GRBs could potentially be produced by binary neutron star (BNS) mergers. The second KN-associated GRB cluster could potentially originate from NS-BH mergers. Future multimessenger observations of compact binaries in gravitational waves (GWs) and electromagnetic waves can be paramount in understanding these clusters better.

The trace anomaly $\Delta\equiv 1/3-P/\varepsilon$ quantifies the possibly broken conformal symmetry in supradense matter under pressure $P$ at energy density $\varepsilon$. Perturbative QCD (pQCD) predicts a vanishing $\Delta$ at extremely high energy or baryon densities when the conformal symmetry is realized but its behavior at intermediate densities reachable in neutron stars (NSs) are still very uncertain. The extraction of $\Delta$ from NS observations strongly depends on the employed model for nuclear Equation of State (EOS). Based on the analytical results from perturbatively analyzing the dimensionless Tolman-Oppenheimer-Volkoff (TOV) equations that are further verified numerically by using $10^5$ EOSs generated randomly with a meta-model in a very broad EOS parameter space constrained by terrestrial nuclear experiments and astrophysical observations, here we first show that the compactness $\xi\equiv M_{\rm{NS}}/R$ of a NS with mass $M_{\rm{NS}}$ and radius $R$ scales very accurately with $\Pi_{\rm{c}}\equiv\mathrm{X}/(1+3\mathrm{X}^2+4\mathrm{X})$ where $\mathrm{X}\equiv P_{\rm{c}}/\varepsilon_{\rm{c}}$ is the ratio of pressure over energy density at NS centers. The scaling of NS compactness thus enables one to readily read off the central trace anomaly $\Delta_{\rm{c}}=1/3-\mathrm{X}$ directly from the observational data of either the mass-radius or red-shift measurements. We then demonstrate indeed that the available NS data themselves from recent X-ray and gravitational wave observations can determine model-independently the trace anomaly as a function of energy density in NS cores, providing a stringent test of existing NS models and a clear guidance in a new direction for further understanding the nature and EOS of supradense matter.

First-order primordial curvature perturbations are known to induce gravitational waves at the second-order, which can in turn probe the small-scale curvature perturbations near the end of the inflation. In this work, we extend the previous analysis in the Gaussian case into the non-Gaussian case, with particular efforts to obtain some thumb rules of sandwiching the associated peaks in gravitational waves induced from multiple peaks of non-Gaussian curvature perturbations.

Filaments of cold gas ($T\leq 10^{4}$ K) are found in the inner regions of many cool-core clusters. These structures are thought to play a major role in the regulation of feedback from active galactic nuclei (AGN). We study the morphology of the filaments, their formation, and their impact on the propagation of the outflowing AGN jets. We present a set of GPU-accelerated 3D (magneto)hydrodynamical simulations of an idealized Perseus-like cluster using the performance portable code AthenaPK. We include radiative cooling, and a self-regulated AGN feedback model that redistributes accreted material through kinetic, thermal and magnetic feedback. We confirm that magnetic fields play an important role in both the formation and evolution of the cold material. These suppress the formation of massive cold disks and favor magnetically supported filaments over clumpy structures. Achieving resolutions of $25-50$ pc, we find that filaments are not monolithic as they contain numerous and complex magnetically--supported substructures. We find that the mass distribution of these clumps follows a power law for all investigated filaments, consistent with previous cloud-crushing simulations of individual clumps. Studying the evolution of individual filaments, we find that their formation pathways can be diverse. We find examples of filaments forming through a combination of cold gas uplifting and condensation, as well as systems of purely infalling clumps condensing out of the intracluster medium. The density contrast between the cold gas and the outflowing hot material leads to recurring deflections of the jets, favoring inflation of bubbles.

The JWST Advanced Deep Extragalactic Survey (JADES) is a multi-cycle JWST program that has taken among the deepest near-infrared images to date (down to $\sim$30.5 ABmag) over $\sim$25 arcmin$^2$ in the GOODS-S field in two sets of observations with one year of separation. This presented the first opportunity to systematically search for transients, mostly supernovae (SNe), out to $z>$2. We found 79 SNe: 38 at $z<$2, 23 at 2$<z<$3, 8 at 3$<z<$4, 7 at 4$<z<$5, and 3 with undetermined redshifts, where the redshifts are predominantly based on spectroscopic or highly reliable JADES photometric redshifts of the host galaxies. At this depth, the detection rate is $\sim$1-2 per arcmin$^2$ per year, demonstrating the power of JWST as a supernova discovery machine. We also conducted multi-band follow-up NIRCam observations of a subset of the SNe to better constrain their light curves and classify their types. Here, we present the survey, sample, search parameters, spectral energy distributions (SEDs), light curves, and classifications. Even at $z\geq$2, the NIRCam data quality is such that we can perform multi-epoch light-curve fitting to classify supernovae with a reasonable degree of confidence. The multi-epoch SN sample includes a Type Ia SN at $z_{spec}= $ 2.91, Type IIP SN at $z_{spec}= $ 3.61, and a Type Ic-BL SN at $z_{spec}= $ 2.845. We also found that two $z\sim$16 galaxy candidates from the first imaging epoch were actually transients that faded in the second epoch, illustrating the possibility that moderate/high-redshift SNe could mimic high-redshift dropout galaxies.

We present JWST NIRCam and NIRSpec observations of a Type Ic supernova (SN Ic) and its host galaxy (JADES-GS+53.13533-27.81457) at $z = 2.83$. This SN (named SN 2023adta) was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) Program. Follow-up observations with JWST/NIRSpec provided a spectroscopic redshift of $z = 2.83$ and the classification as a SN Ic-BL. The light curve of SN 2023adta matches well with other stripped envelope supernovae and we find a high peak luminosity, $M_V = -19.0 \pm 0.2$ mag, based on the distribution of best-fit SNe. The broad absorption features in its spectrum are consistent with other SNe Ic-BL 1-3 weeks after peak brightness. We measure a Ca II NIR triplet expansion velocity of $29{,}000 \pm 2{,}000$ km s$^{-1}$. The host galaxy of SN 2023adta is irregular, and modeling of its spectral energy distribution (SED) indicates a metallicity of $Z = 0.35^{+0.16}_{-0.08} Z_{\odot}$. This environment is consistent with the population of low-$z$ SNe Ic-BL which prefer lower metallicities relative to other stripped envelope supernovae, and track long duration $\gamma$-ray burst (LGRB) environments. We do not identify any GRBs that are coincident with SN 2023adta. Given the rarity of SNe Ic-BL in the local universe, the detection of a SN Ic-BL at $z = 2.83$ could indicate that their rates are enhanced at high redshift.

Pulsar Timing Array projects have found evidence of a stochastic background of gravitational waves (GWB) using data from an ensemble of pulsars. In the literature, minimal assumptions are made about the signal and noise processes that affect data from these pulsars, such as pulsar spin noise. These assumptions are encoded as uninformative priors in Bayesian searches, though Frequentist approaches make similar assumptions. Uninformative priors are not suitable for (noise) properties of pulsars in an ensemble, and they bias estimates of model parameters such as gravitational-wave signal parameters. Both Frequentist and Bayesian searches are affected. In this letter, more appropriate priors are proposed in the language of Hierarchical Bayesian Modeling, where the properties of the ensemble of pulsars are jointly described with the properties of the individual components of the ensemble. Results by Pulsar Timing Array projects should be re-evaluated using Hierarchical Models.

We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS$+53.13485$$-$$27.82088$ with a host spectroscopic redshift of $2.903\pm0.007$. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (E(B-V)$\sim0.9$) despite a host galaxy with low-extinction and has a high Ca II velocity ($19,000\pm2,000$km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-z Ca-rich population. Although such an object is too red for any low-z cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement ($\lesssim1\sigma$) with $\Lambda$CDM. Therefore unlike low-z Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-z truly diverge from their low-z counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.

Understanding the characteristics of young stellar populations is essential for deriving insights into star formation processes within parent molecular clouds and the influence of massive stars. This study focuses on YSOs in the G 045.49+00.04 molecular cloud, including three UC HII regions. Using infrared photometric data and radiation models, we identified 1482 YSOs with masses ranging from 1.5 to 22 Msol. Among these, 315 form dense clusters near IRAS sources, with high-mass stars responsible for ionization. The non-cluster YSOs (1168) are uniformly distributed on the field. The distribution of YSOs from both samples on the colour-magnitude diagram and by the evolutionary ages is different. About 75% of objects in the IRAS clusters are concentrated around the ZAMS and have a well-defined peak at an age of Log(Age[years]) = 6.75, with a narrow spread. The non-cluster objects have two concentrations located to the right and left of the 0.1 Myr isochrone and two well-defined peaks at Log(Age) = 6.25 and 5.25. The K luminosity functions alpha slopes for the IRAS clusters and non-cluster objects are 0.32 and 0.72, respectively. The steeper alpha slope is suggesting that the non-cluster objects are less evolved, which is well consistent with the evolutionary age. Similar patterns were observed in the neighboring G 45.14+00.14 region. The both regions (G 045.49+00.04 and G 45.14+00.14) are located and distinguished by their brightness and density at the edge of the bubble around the highly variable X-ray binary GRS 1915+105, which includes a black hole and a K-giant companion. Based on the above, we can assume that the process of star formation in the young IRAS clusters was triggered by the GRS 915+105-initiated shock front inside the ISM massive condensation, through the process of "collecting and collapse". Most non-cluster objects probably belong to a later generation.

The interactions between the Magellanic Clouds significantly affect the shape and distribution of the young stellar population, particularly in the periphery of the Small Magellanic Cloud (SMC). We present the first far-UV (FUV) map of the north-east SMC-Shell region using the Ultra Violet Imaging Telescope (UVIT) onboard AstroSat. The detected FUV stars are combined with Gaia Early Data Release 3 data to create a FUV-optical catalog of ~ 14,400 stars. FUV-optical colour-magnitude diagrams are used along with isochrones to estimate the stellar ages. The detected stars are formed in multiple episodes. We identified two episodes of star formation (~ 60 and ~ 260 Myr ago) where the episode at ~ 260 Myr is linked to the recent interaction with the Large Magellanic Cloud (LMC) and the episode at ~ 60 Myr is linked to the pericentric passage of the SMC around our Galaxy. The median proper motion (PM) and velocity dispersion are found to be similar to the SMC main body, indicating that this region has not experienced significant tidal effects. The FUV stellar surface density and the dispersion in PM suggest an extent of the inner SMC in the north-east direction to be around 2.2 deg. We detect arm-like and arc-like structures in the FUV stellar density map, and their kinematics appear to be similar to the SMC main body. These extended outer features are the spatial stellar overdensities formed over multiple episodes of star formation, but without apparent kinematic distinction.

In this work, we develop a simulation-based model to predict the density split (DSS) and second-order shear and clustering statistics. A simulation-based model has the potential to model highly non-linear scales where current DSS models fail. To build this model, we use the \texttt{AbacusSummit} N-body simulation suite from which we measure all necessary statistics and train an emulator based on \texttt{CosmoPower}. In that context, we discuss possible improvements for future emulators to make the measurement less noisy and biased, resulting in more accurate and precise model predictions. Regarding the emulator's accuracy, we find that the most important aspect is the average of the summary statistics over multiple-shot noise realizations of the foreground galaxies. However, these results probably depend on the chosen number density of the foreground galaxies. Regarding the parameter forecast based on preliminary LOWZxUNIONS data, we find that DSS has more constraining power to derive cosmological parameters and that the joint analysis with second-order statistics is particularly useful for extracting parameters of the galaxy-halo connection.

One of the most exciting benefits of solar small-scale brightening is their oscillations, this study investigated the properties of small-scale brightening (SSBs) in different regions of the Sun and found that there are differences and similarities in the properties of oscillated and non-oscillated SSBs in different regions of the Sun, including quiet Sun (QS), the adjacent to active regions (AAR), and coronal hole (CH). The damping per period (Q-factor) and maximum Doppler velocity of SSBs varied depending on the region, with the less bright internetwork SSBs in QS having lower damping time (120 seconds) and higher maximum Doppler velocities (47 km/s) compared to the brighter network SSBs (with 216 seconds & 37 km/s, respectively), while in AAR, internetwork SSBs tend to have higher damping time (about of 220 seconds) and wider maximum Doppler velocity (10 to 140 km/s) ranges compared to network SSBs (130 seconds & 10 to 85 km/s). In CH, both types of SSBs show similar damping time (120 seconds), but internetwork SSBs tend to have higher maximum Doppler velocities (100 km/s) compared to network SSBs (85 km/s). Also, it was pointed out that the majority of network SSBs in AARs are in the overdamping mode, while in QS, internetwork SSBs demonstrate overdamping behavior and oscillated network SSBs exhibit critical damping behavior. It is important to bear in mind, however, that the physical mechanisms underlying the damping of SSBs may vary depending on the local plasma conditions and magnetic environment.

The SRG/eROSITA All-Sky Survey (eRASS) is expected to contain ~100 quasars that emitted their light when the universe was less than a billion years old, i.e. at z>5.6. By selection, these quasars populate the bright end of the AGN X-ray luminosity function and their count offers a powerful demographic diagnostic of the parent super-massive black hole population. Of the >~ 400 quasars that have been discovered at z>5.6 to date, less than 15 % have been X-ray detected. We present a pilot survey to uncover the elusive X-ray luminous end of the distant quasar population. We have designed a quasar selection pipeline based on optical, infrared and X-ray imaging data from DES DR2, VHS DR5, CatWISE2020 and the eRASS. The core selection method relies on SED template fitting. We performed optical follow-up spectroscopy with the Magellan/LDSS3 instrument for the redshift confirmation of a subset of candidates. We have further obtained a deeper X-ray image of one of our candidates with Chandra ACIS-S. We report the discovery of five new quasars in the redshift range 5.6 < z < 6.1. Two of these quasars are detected in eRASS and are by selection X-ray ultra-luminous. These quasars are also detected at radio frequencies. The first one is a broad absorption line quasar which shows significant X-ray dimming over 3.5 years, i.e. about 6 months in the quasar rest frame. The second radio-detected quasar is a jetted source with compact morphology. We show that a blazar configuration is likely for this source, making it the second most distant blazar known to date. With our pilot study, we demonstrate the power of eROSITA as a discovery machine for luminous quasars in the epoch of reionization. The X-ray emission of the two eROSITA detected quasars are likely to be driven by different high-energetic emission mechanisms a diversity which will be further explored in a future systematic full-hemisphere survey.

Cosmic shear is a powerful probe of cosmology, but it is affected by the intrinsic alignment (IA) of galaxy shapes with the large-scale structure. Upcoming surveys like Euclid and Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) require an accurate understanding of IA, particularly for higher-order cosmic shear statistics that are vital for extracting the most cosmological information. In this paper, we report the first detection of third-order IA correlations using the LOWZ galaxy sample from the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey (BOSS). We compare our measurements with predictions from the MICE cosmological simulation and an analytical NLA-inspired model informed by second-order correlations. We also explore the dependence of the third-order correlation on the galaxies' luminosity. We find that the amplitude $A_\mathrm{IA}$ of the IA signal is non-zero at the $4.7\sigma$ ($7.6\sigma$) level for scales between $6 h^{-1} \mathrm{Mpc}$ ($1 h^{-1} \mathrm{Mpc}$) and $20 h^{-1} \mathrm{Mpc}$. For scales above $6 h^{-1}\mathrm{Mpc}$ the inferred AIA agrees both with the prediction from the simulation and estimates from second-order statistics within $1\sigma$ but deviations arise at smaller scales. Our results demonstrate the feasibility of measuring third-order IA correlations and using them for constraining IA models. The agreement between second- and third-order IA constraints also opens the opportunity for a consistent joint analysis and IA self-calibration, promising tighter parameter constraints for upcoming cosmological surveys.

We study how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We develop a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral fluctuations and the correlations between different frequencies. As GW emission circularizes binaries, the suppression of the signal strength due to eccentricity will be relevant for signals from wider binaries emitting at lower frequencies. Such a feature is present in the signal observed at pulsar timing arrays. We find that, when orbital decay of the SMBH binaries is driven by GWs only, the shape of the observed signal prefers highly eccentric binaries $\langle e \rangle_{2\,{\rm nHz}} = 0.83^{+0.04}_{-0.05}$. However, when environmental effects are included, the initial eccentricity can be significantly lowered yet the scenario with purely circular binaries is mildly disfavored.