Papers for Wednesday, Apr 09 2025

In the past few decades, large universal structures have been found that challenge the homogeneity and isotropy expected in standard cosmological models. The largest of these, identified as the Hercules-Corona Borealis Great Wall, was found in 2014 in the northern galactic hemisphere in the redshift range of 1.6 < z < 2.1. Subsequent studies used an increasing gamma-ray burst database to show that the cluster was unlikely to have been caused by statistical sampling uncertainties. This study re-examines burst clustering in the northern galactic hemisphere using a recently developed methodology. Evidence is provided that the Hercules-Corona Borealis Great Wall cluster is larger than previously thought, with members potentially spanning the redshift range of 0.33 < z < 2.43. The extension of this cluster's size does not appear to have been due to statistical variations or sampling biases.

The Five-hundred-meter Aperture Spherical Telescope is discovering hundreds of new pulsars, including a slowly spinning compact binary millisecond pulsar (spin period $P_{\rm spin}=14.2$ ms) which showed radio eclipses and evidence of ablation of its companion: PSR J1932+2121. Its orbital period is $P_{\rm orb}=0.08$ d and the minimum companion mass is estimated as 0.12 $M_{\odot}$. Hence, this pulsar is classified as part of the Galactic-field spider (redback) population. However, it spins almost an order of magnitude slower than other Galactic-field spiders. Using detailed evolutionary calculations with MESA, we model the formation, mass-transfer and radio-pulsar phases, in order to explain the observed properties of PSR J1932+2121. We find that PSR J1932+2121 is a redback that has experienced an inefficient mass-transfer phase resulting in a lower accretion efficiency (in the range of 0.3 to 0.5) and subsequently slower spin compared to other spiders. We narrow down the initial range of $P_{\rm orb}$ that best reproduces its properties, to 2.0 to 2.6\,d. Current models of accretion-induced magnetic field decay are not able to explain its unusually high surface magnetic field of $2\times 10^{9}$ G. Hence, PSR J1932+2121 provides a unique opportunity to study inefficient accretion-induced spin up and surface magnetic field decay of pulsars.

Radiative losses play a critical role in the cooling of plasmas. When chromospheric plasma is sufficiently heated, it can flow into coronal loops which subsequently cool down due to radiation. From observations, we infer that this cooling does not occur uniformly, often resulting in coronal condensations such as coronal rain. To date, coronal condensations have only been found in simulations of steadily-heated loops, and never in impulsively-heated ones. We implement spatiotemporally variable elemental abundances in a radiative hydrodynamic code. Flows, including chromospheric evaporation, directly cause a shift in the local elemental abundances, which then affects the local radiative loss rate. As a consequence, we find that incorporating spatiotemporal low FIP elemental abundances into coronal loop simulations directly causes coronal condensations, which are otherwise absent in impulsively heated loop or flare models. We conclude that spatiotemporal variations in elemental abundances are a fundamental feature of the solar corona, and are therefore necessary to accurately model radiation.

The cosmic far-infrared background (CIB) encodes dust emission from all galaxies and carries valuable information on structure formation, star formation, and chemical enrichment across cosmic time. However, its redshift-dependent spectrum remains poorly constrained due to line-of-sight projection effects. We address this by cross-correlating 11 far-infrared intensity maps spanning a 50-fold frequency range from Planck, Herschel, and IRAS, with spectroscopic galaxies and quasars from SDSS I-IV tomographically. We mitigate foregrounds using CSFD, a CIB-free Milky Way dust map. These cross-correlation amplitudes on two-halo scales trace bias-weighted CIB redshift distributions and collectively yield a $60\sigma$ detection of the evolving CIB spectrum, sampled across hundreds of rest-frame frequencies over $0 < z < 4$. We break the bias-intensity degeneracy by adding monopole information from FIRAS. The recovered spectrum reveals a dust temperature distribution that is broad, spanning the full range of host environments, and moderately evolving. Using low-frequency CIB amplitudes, we constrain cosmic dust density, $\Omega_{\rm dust}$, which peaks at $z = 1$-$1.5$ and declines threefold to the present. Our broad spectral coverage enables a determination of the total infrared luminosity density to 0.04 dex precision, tracing star-formation history with negligible cosmic variance across 90% of cosmic time. We find that cosmic star formation is 80% dust-obscured at $z = 0$ and 60% at $z = 4$. Our results, based on intensity mapping, are complete, requiring no extrapolation to faint galaxies or low-surface-brightness components. We release our tomographic CIB spectrum and redshift distributions as a public resource for future studies of the CIB, both as a cosmological matter tracer and CMB foreground.

The nano-hertz (nHz) stochastic gravitational wave background (SGWB), produced by unresolved supermassive black hole binaries (SMBHBs), offers a unique probe of their cosmic evolution. Using our recently proposed technique, we investigate the prospect of discovering the SMBHB population and its evolution by combining the SGWB signal and its anisotropies with galaxy observation by exploring their cross-correlation. Using a Fisher analysis, we demonstrate that the SGWB power spectrum alone can provide only a weak measurement of the cosmic genealogy of SMBHBs, while the inclusion of the angular power spectrum of SGWB and its cross-correlation with the galaxy distribution can significantly improve our measurement and open a discovery space. With a PTA of 2000 pulsars, achievable in the SKA era, we find that the redshift evolution of the supermassive black hole (SMBH) mass and galaxy stellar mass can be measured with an SNR up to 4 in the redshift range up to three. The frequency distribution can be constrained with an SNR of approximately up to 80 in the same redshift range at a frequency range accessible from nHz. These SNRs improve further with the increase in the number of pulsars to 5000 expected from SKA. This demonstrates the prospect of answering the decades-long unsolved problem of SMBH growth and evolution over cosmic time and shedding new insights on the standard model of cosmology using synergy between nHz GW and galaxy surveys.

Planet-forming discs in sufficiently strong UV environments lose gas in external photoevaporative winds. Dust can also be entrained within these winds, which has consequences for the possible solids reservoir for planet formation, and determines the shielding of the disc by the wind. This has previously been studied in 1D models, with predictions for the maximum entrained size, as well as a predicted population of stalled dust of decreasing grain size with distance from the disc. We wrote and tested a new dust particle solver to make the first study of the entrainment and dynamics of dust, using steady state solutions of state-of-the-art 1D and 2D radiation hydrodynamic simulations of externally photoevaporating discs. In our 1D models, we only consider the outer disc at the midplane, verifying previous studies. In our 2D simulations, the wind is launched from the disc surface, as well as the disc edge. In 2D we find that the maximum entrained grain size varies substantially with angle relative to the plane of the disc, from $\sim100$$\mu$m near the disc outer edge down to $\sim1$$\mu$m or even sub-micron in the weaker wind from the disc surface. The gradient of stalled dust seen in 1D also only appears near the disc outer edge in 2D, but not from the disc surface. This agrees qualitatively with observations of silhouette discs in the Orion Nebula Cluster. Despite the spatial variation of the dust, the extinction of the UV radiation remains fairly uniform due to the opacity being dominated by the small grains, and depends more on the dust distribution within the disc itself.

Spicules are elongated, jet-like structures that populate the solar chromosphere and are rooted in the photosphere. In recent years, high-resolution observations and advanced numerical simulations have provided insights into their properties, structures, and dynamics. However, the formation mechanism of spicules, particularly the more dynamic type II spicules, which are primarily found in the quiet Sun and coronal holes, remains elusive. This study explores whether quiet Sun Ellerman bombs (QSEBs), which are ubiquitous small-scale magnetic reconnection events in the lower atmosphere, are linked to the formation of type II spicules. We analysed a high-quality 40-minute time sequence acquired with the Swedish 1-m Solar Telescope. H-beta data were used to observe QSEBs and spicules, while spectropolarimetric measurements in the photospheric Fe i 6173 A line provided line-of-sight magnetic field information. We employed k-means clustering to automatically detect QSEBs and explored their potential association with spicules. We identified 80 clear cases where spicules occurred soon after the QSEB and not later than 30 s after the ending of the QSEBs. All events involved type II spicules, rapidly fading from the images. The footpoints of the spicules seemed to be rooted in QSEBs, where the onset of QSEBs often preceded the formation of the associated spicules. Additionally, we found around 500 other events that hinted at a connection but with some ambiguities. The combined clear and ambiguous cases constitute 34% of the total detected QSEBs and a smaller percentage of the spicules in our dataset. Our findings suggest that a fraction of type II spicules originate from QSEBs, supporting magnetic reconnection as a potential driving mechanism. In this context, QSEBs and spicules represent the conversion of magnetic energy into thermal and kinetic energy, respectively.

Protoplanetary disks observed edge-on commonly show asymmetries that can be caused by shadows cast from a warp. With the growing amount of these observations, methods to constrain warp parameters are urgently needed. In this work, we investigate observational signatures of warps in edge-on disks with the aim to find limits on the observability of warps. We perform radiative transfer simulations in scattered light (near-/mid-infrared) of edge-on disks containing warps of different amplitudes and varying sizes of the misaligned inner region. We analyze the effect of these parameters at 0.8 micron, but also compare models for specific parameters at wavelengths up to 21 micron. In all models, we quantify the apparent asymmetry. We find that under optimal conditions, an asymmetry due to slight warps can be visible. The visibility depends on the viewing angle, as warped disks are not axisymmetric. For optimal azimuthal orientation, misalignments between inner and outer disk regimes as low as 2° can lead to significant asymmetries. On the other hand, we find that larger misalignments of about 10° are needed in order to observe a change in the brightest nebula as a function of wavelength, which is observed in a few protoplanetary disks. In order to link our results to observations, we investigate potential misalignments between the inner and outer disk of edge-on systems showing asymmetries. We compare the jet geometry, which traces the inner region of the disk, to the outer disk orientation and find that a misalignment of a few degrees could be present, such that warped disks could explain the apparent lateral asymmetries. There are many factors that can influence the appearance of the shadows and asymmetries in warped disks. Although it is still challenging to infer exact warp parameters from observations, this work presents a promising step toward better constraints.

The data collected by the Wide-field Infrared Survey Explorer (WISE, Wright et al. 2010) and its follow-up Near Earth Object (NEO) mission (NEOWISE, Mainzer et al. 2011) represent a treasure trove for variability studies. However, the angular resolution imposed by the primary mirror implies that close double stars are often unresolved. Then, variability of one or both stars leads to motion of the image centroid along the connecting line. Such an object is known as a "variability-induced mover" (VIM). Knowledge of the angular separation, derived from higher-resolution imaging which resolves both components, allows disentangling of the joint light curve into individual ones. This is illustrated by the case of SPICY 1474 which featured an outburst several years ago. Removal of the contribution of the nearby companion, which led to a dilution of the burst strength, revealed that it was ~0.5 mag brighter than in the joint light curve. A comparison with light curves from unTimely suggests that utilizing the photocenter shift may lead to more reliable results.

Stellar rotation and magnetic activity have a complex evolution that reveals multiple regimes. One of the related transitions that is seen in the rotation distribution for main-sequence (MS) solar-like stars has been attributed to core-envelope coupling and the consequent angular-momentum transfer between a fast core and a slow envelope. This feature is known as spin-down stalling and is related to the intermediate-rotation gap seen in field stars. Beyond this rotation signature, we search for evidence of it in stellar magnetic activity. We investigated the magnetic activity of the 1 Gyr old NGC 6811, a Kepler-field cluster, and Kepler MS stars of different ages. The magnetic activity was measured through the photometric magnetic activity proxy, Sph. To characterize the evolution of the magnetic activity for the Kepler sample, we split it according to the relative rotation and computed the respective activity sequences. We found the signature of core-envelope coupling in the magnetic activity of NGC 6811 and in the Kepler MS sample. In NGC 6811, we found enhanced magnetic activity for a range of effective temperatures that remained for significant timescales. In the Kepler sample, the magnetic activity sequences pile up in two distinct regions: at high activity levels that coincide with stars near the stalling mentioned above, where a behavior inversion is observed (slowly rotating stars have higher activity levels than fast-rotating stars, which is opposite to the overall behavior); and at low activity levels corresponding to slow rotators close to the detection limit, potentially facing a weakening of the magnetic braking. These results support the recent proposition that the strong shear experienced by stars during the core-envelope coupling phase can cause enhanced activity. This study helps us to shed light on the interplay between rotation, magnetic activity, and their evolution.

We investigate the environmental impact of cluster regions on the evolution of nearby S0 galaxies, focusing on their distinct quiescent and star-forming (SF) subpopulations. We select a sample of clusters by crossmatching optical and X-ray data and extract a subset of 14 systems with maximally relaxed cores by applying strict virialization and substructure tests. A projected phase space (PPS) diagram is generated from the stack of relaxed clusters up to 3 virial radii to assess the locations of quiescent and SF S0s and their cluster infall histories. Additionally, we compare the radial line-of-sight velocity dispersion (VDLOS) and specific star-formation rate (SSFR) profiles for the different S0 subpopulations, using other Hubble types as benchmarks. Our study shows that quiescent S0s, the dominant class in the entire cluster region, concentrate preferentially at low radii in the PPS diagram, while SF S0s are more abundant in the outskirts. Despite this segregation, both subpopulations show similar VDLOS profiles in the cluster core -indicating an advanced stage of dynamical relaxation-, but that resemble those of late-type galaxies beyond the virial radius. This finding, combined with the distinct PPS distributions of both S0 subpopulations, which lead to mean infall times $\sim 1$ Gyr longer for quiescent S0s but that are shorter than those expected for ancient infallers, suggests that a substantial fraction of S0s present in the core region arrive via secondary infall. We also find evidence in the SSFR profiles that star formation in S0s begins to decline beyond the virialized core, likely due to preprocessing in infalling groups. Our results support a delayed-then-rapid quenching scenario for SF S0s in cluster regions, where their centrally concentrated star formation persists for an extended period before abruptly ending ($\lesssim 0.1$ Gyr) after their first pericenter passage.

The third science flight of the balloon-borne solar observatory Sunrise carries three entirely new post-focus science instruments with spectropolarimetric capabilities, concurrently covering an extended spectral range from the near ultraviolet to the near infrared. Sampling a larger height range, from the low photosphere to the chromosphere, with the sub-arcsecond resolution provided by the 1-m Sunrise telescope, is key in understanding critical small-scale phenomena which energetically couple different layers of the solar atmosphere. The Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) operates between 309 nm and 417 nm. A key feature of SUSI is its capability to record up to several hundred spectral lines simultaneously without the harmful effects of the Earth's atmosphere. The rich SUSI spectra can be exploited in terms of many-line inversions. Another important innovation of the instrument is the synchronized 2D context imaging which allows to numerically correct the spectrograph scans for residual optical aberrations. In this work we describe the main design aspects of SUSI, the instrument characterization and testing, and finally its operation, expected performance and data products.

We analyzed the incidence and properties of RR Lyrae stars that show evidence for amplitude and phase modulation (the so-called Blazhko Effect) in a sample of $\sim$3,000 stars with LINEAR and ZTF light curve data collected during the periods of 2002-2008 and 2018-2023, respectively. A preliminary subsample of about $\sim$500 stars was algorithmically pre-selected using various data quality and light curve statistics, and then 228 stars were confirmed visually as displaying the Blazhko effect. This sample increases the number of field RR Lyrae stars displaying the Blazhko effect by more than 50\% and places a lower limit of (11.4$\pm$0.8)\% for their incidence rate. We find that ab type RR Lyrae that show the Blazhko effect have about 5\% (0.030 day) shorter periods than starting sample, a 7.1$\sigma$ statistically significant difference. We find no significant differences in their light curve amplitudes and apparent magnitude (essentially, signal-to-noise ratio) distributions. No period or other differences are found for c type RR Lyrae. We find convincing examples of stars where the Blazhko effect can appear and disappear on time scales of several years. With time-resolved photometry expected from LSST, a similar analysis will be performed for even larger samples of field RR Lyrae stars in the southern sky and we anticipate a higher fraction of discovered Blazhko stars due to better sampling and superior photometric quality.

The evolution of young stars and planet-forming environments is intrinsically linked to their nascent surroundings. This is particularly evident for FU Orionis (FUor) objects$-$a class of young protostars known for dramatic outbursts resulting in significant increases in brightness. We present a case study of V960 Mon, an FUor that has recently been found to show signs of a fragmenting spiral arm, potentially connected to planet formation. Our study explores the large-scale environment ($10^3-10^4$ au) and incorporates ALMA band 3, band 4 and band 6 continuum data, molecular emissions from $^{12}$CO, $^{13}$CO, C$^{18}$O, SiO, DCO$^+$, N$_2$D$^+$ and DCN, alongside optical and near-infrared observations from VLT/MUSE and VLT/SPHERE. We map a region of 20" across where we find tantalizing emissions that provide a unique view of a young group of protostars, including the discovery of a class-0 protostar to the east of the FUor. The $^{12}$CO and SiO tracers suggest that this object is at the base of an outflow, potentially impacting the surrounding medium. The MUSE and SPHERE observations indicate the presence of an elongated feature towards a prominent source to the southeast that may represent interaction between V960 Mon and its surrounding. Moreover, the C$^{18}$O emission overlaps with the clumps of the detected fragmenting spiral arm. These findings provide the strongest evidence to date for a connection between infalling material, fragmentation, and the intensity outburst of a protostar. Our case study highlights the complex interactions between young stars and their surroundings that drive the evolution of the planet forming environment.

Specifically selected to leverage the unique ultraviolet capabilities of the Hubble Space Telescope, the Hubble Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) is a Director's Discretionary program of approximately 1000 orbits - the largest ever executed - that produced a UV spectroscopic library of O and B stars in nearby low metallicity galaxies and accreting low mass stars in the Milky Way. Observations from ULLYSES combined with archival spectra uniformly sample the fundamental astrophysical parameter space for each mass regime, including spectral type, luminosity class, and metallicity for massive stars, and the mass, age, and disk accretion rate for low-mass stars. The ULLYSES spectral library of massive stars will be critical to characterize how massive stars evolve at different metallicities; to advance our understanding of the production of ionizing photons, and thus of galaxy evolution and the re-ionization of the Universe; and to provide the templates necessary for the synthesis of integrated stellar populations. The massive star spectra are also transforming our understanding of the interstellar and circumgalactic media of low metallicity galaxies. On the low-mass end, UV spectra of T Tauri stars contain a plethora of diagnostics of accretion, winds, and the warm disk surface. These diagnostics are crucial for evaluating disk evolution and provide important input to assess atmospheric escape of planets and to interpret powerful probes of disk chemistry, as observed with ALMA and JWST. In this paper we motivate the design of the program, describe the observing strategy and target selection, and present initial results.

We report observations of solar spicules at millimeter wavelengths (mm-$\lambda$) using the Atacama Large Millimeter/submillimeter Array (ALMA). These are supplemented by observations in optical (O), ultraviolet (UV) and extreme ultraviolet (EUV) wavelengths. The observations were made on 2018 December 25 of the northern polar coronal hole. ALMA obtained time-resolved imaging observations at wavelengths of 3 mm (100 GHz; 2~s cadence) and 1.25~mm (239 GHz; $\approx 2$~min cadence) with an angular resolution of $2.2" \times 1.3"$ and $1.5" \times 0.7"$, respectively. Spicules observed at mm-$\lambda$ are easily seen low in the chromosphere whereas spicules in UV bands are seen to extend higher. The spicules observed at mm-$\lambda$ are seen in absorption against coronal EUV emission, allowing us to estimate the column depth of neutral hydrogen. Spicular emission at mm-$\lambda$, due to thermal free-free radiation, allows us to estimate the electron number density as a function of height. We find that spicule densities, inferred from the mm-$\lambda$ data are uniquely insensitive to assumptions regarding the temperature of plasma in spicules. We suggest that the upward mass flux carried by spicules is unlikely to play a significant role in the mass budget of the solar corona and solar wind, and the transport of hot material into the corona by spicules may not play a significant role in coronal heating. However, the possibility that electric currents, fast kink and torsional waves, or other wave modes carried by spicules may play a role in transporting energy into the solar corona cannot be excluded.

In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multi-wavelength campaign (using VLA, Chandra/HETG, and NICER) on the near-Eddington neutron-star Z source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z-track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations-contrary to typical behavior in Z-sources-and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.

Event Horizon Telescope (EHT) observations of M87* provide a means of constraining parameters of both the black hole and its surrounding plasma. However, intrinsic variability of the emitting material introduces a major source of systematic uncertainty, complicating parameter inference. The precise origin and structure of this variability remain uncertain, and previous studies have largely relied on general relativistic magnetohydrodynamic (GRMHD) simulations to estimate its effects. Here, we fit a semi-analytic, dual-cone model of the emitting plasma to multiple years of EHT observations to empirically assess the impact of intrinsic variability and improved array coverage on key measurements including the black hole mass-to-distance ratio, spin, and viewing inclination. Despite substantial differences in the images of the two epochs, we find that the inferred mass-to-distance ratio remains stable and mutually consistent. The black hole spin is unconstrained for both observations, despite the improved baseline coverage in 2018. The inferred position angle and inclination of the black hole spin axis are discrepant between the two years, suggesting that variability and model misspecification contribute significantly to the total error budget for these quantities. Our findings highlight both the promise and challenges of multi-epoch EHT observations: while they can refine parameter constraints, they also reveal the limitations of simple parametric models in capturing the full complexity of the source. Our analysis -- the first to fit semi-analytic emission models to 2018 EHT observations -- underscores the importance of systematic uncertainty quantification from intrinsic variability in future high-resolution imaging studies of black hole environments and the role of repeated observations in quantifying these uncertainties.

The hypothesized Planet Nine is thought to reside in the distant outer solar system, potentially explaining various anomalies in the orbits of extreme trans-Neptunian objects (ETNOs). In this work, we present a targeted observational search for Planet Nine, motivated by a possible gravitational interaction with the interstellar meteoroid responsible for the CNEOS14 bolide. Our observations span two campaigns over 2022 and 2023, covering a 98-square-degree region where Planet Nine's position is most likely if the messenger hypothesis holds. Our data and search methodology, based on the detection of parallax position shifts between consecutive nights, provide 85% confidence exclusion limits for objects with Sloan r-band magnitudes brighter than between 21.0 and 21.4, with an average sensitivity limit of 21.3. No credible Planet Nine candidates were identified within this field and magnitude limits. A caveat to our approach is that it would miss a candidate if its position were affected by scattered light from bright stars in at least one of the nights. However, we estimate that the probability for this is very low, around 0.4%. We discuss several possible reasons for our Planet Nine non-detection. Our study complements prior searches, particularly those using archival survey data that are limited in the Galactic plane or at fainter brightness limits. While our consecutive-night observation approach offers high sensitivity to minimal motion, extending the search for Planet Nine to fainter magnitudes (which may be crucial, according to recent predictions), will require higher sensitivity instrumentation.

Eccentric giant planets are predicted to have acquired their eccentricity through two major mechanisms: the Kozai-Lidov effect or planet-planet scattering, but it is normally difficult to separate the two mechanisms and determine the true eccentricity origin for a given system. In this work, we focus on a sample of 92 transiting, long-period giant planets (TLGs) as part of an eccentricity distribution study for this planet population in order to understand their eccentricity origin. Using archival high-contrast imaging observations, public stellar catalogs, precise Gaia astrometry, and the NASA Exoplanet Archive database, we explored the eccentricity distribution correlation with different planet and host-star properties of our sample. We also homogeneously characterized the basic stellar properties for all 86 host-stars in our sample, including stellar age and metallicity. We found a correlation between eccentricity and stellar metallicity, where lower-metallicity stars ([Fe/H] <= 0.1) did not host any planets beyond e > 0.4, while higher-metallicity stars hosted planets across the entire eccentricity range. Interestingly, we found no correlation between the eccentricity distribution and the presence of stellar companions, indicating that planet-planet scattering is likely a more dominant mechanism than the Kozai-Lidov effect for TLGs. This is further supported by an anti-correlation trend found between planet multiplicity and eccentricity, as well as a lack of strong tidal dissipation effects for planets in our sample, which favor planet-planet scattering scenarios for the eccentricity origin.

Observations of massive, quiescent galaxies reveal a relatively uniform evolution: following prolific star formation in the early universe, these galaxies quench and transition to their characteristic quiescent state in the local universe. The debate on the relative role and frequency of the process(es) driving this evolution is robust. In this letter, we identify 0.5<z<1.5 massive, quiescent galaxies in the HST/UVCANDELS extragalactic deep fields using traditional color selection methods and model their spectral energy distributions, which incorporates novel UV images. This analysis reveals ~15% of massive, quiescent galaxies have experienced minor, recent star formation(<10% of total stellar mass within the past ~1Gyr). We find only a marginal, positive correlation between the probability for recent star formation and a measure of the richness of the local environment from a statistical analysis. Assuming the recent star formation present in these quiescent galaxies is physically linked to the local environment, these results suggest only a minor role for dynamic external processes (galaxy mergers and interactions) in the formation and evolution of these galaxies at this redshift.

Broad emission line regions (BLRs) lying into central accretion disks has been widely accepted to explain the unique double-peaked broad emission lines in Active Galactic Nuclei (double-peaked BLAGNs). Here, accepted the accretion disk origin, periodic variations of central wavelength $\lambda_{0}$ (the first moment) and line width $\sigma$ (the second moment) of double-peaked broad emission lines are theoretically simulated and determined. Furthermore, through theoretically simulated periodicities of $T_{\lambda0}$ and $T_{\sigma}$ for variations of $\lambda_0$ and $\sigma$, periodicity ratio $R_{fs}$ of $T_{\lambda0}$ to $T_{\sigma}$ to be around 2 can be applied to support the spiral arms to be more preferred in BLRs lying into central accretion disks. Then, periodic variations of $\lambda_0$ and $\sigma$ are determined and shown in the known double-peaked BLAGN NGC1097, leading to the parameter $R_{fs}\sim2$, which can be applied as clues to support that the structure of spiral arms in disk-like BLRs in central accretion disk should be the most compelling interpretation to the variability of double-peaked broad H$\alpha$ in NGC1097. The results provide clean criteria to test accretion disk origins of double-peaked broad emission lines in AGN.

Red Giant Branch (RGB) stars are overwhelmingly observed to rotate very slowly compared to main-sequence stars, but a few percent of them show rapid rotation and high activity, often as a result of tidal synchronizationn or other angular momentum transfer events. In this paper we build upon previous work using a sample of 7,286 RGB stars from APOGEE DR17 with measurable rotation. We derive an updated NUV excess vs $v \sin{i}$ rotation-activity relation that is consistent with our previous published version, but reduces uncertainty through the inclusion of a linear [M/H] correction term. We find that both single stars and binary stars generally follow our rotation-activity relation, but single stars seemingly saturate at $P_{\text{rot}}$/$\sin{i}$ $\sim$10 days while binary stars show no sign of saturation, suggesting they are able to carry substantially stronger magnetic fields. Our analysis reveals Sub-subgiant stars (SSGs) to be the most active giant binaries, with rotation synchronized to orbits with periods $\lesssim$ 20 days. Given their unusually high level of activity compared to other short-period synchronized giants we suspect the SSGs are most commonly overactive RS CVn stars. Using estimates of critical rotation we identify a handful giants rotating near break-up and determine tidal spin up to this level of rotation is highly unlikely and instead suggest planetary engulfment or stellar mergers in a fashion generally proposed for FK Comae stars.

The origin of small deviations from statistical isotropy in the Cosmic Microwave Background (CMB) - the so-called CMB anomalies - remains an open question in modern cosmology. In this work, we test statistical isotropy in Planck Data Release 4 (PR4) by estimating the temperature and $E$-mode power spectra across independent sky regions. We find that the directions with higher local bandpower amplitudes in intensity are clustered for multipoles between 200 and 2000 with clustering probabilities consistently below 1% for all these scales when compared to end-to-end (E2E) Planck simulations; notably, this range extends beyond that reported in Planck Data Release 3 (PR3). On the other hand, no significant clustering is observed in the polarization $E$-modes. In a complementary analysis, we search for dipolar variations in cosmological parameters fitted using the previously computed power spectra. When combining temperature and polarization power spectra, we identify a potential anomaly in the amplitude of the primordial power spectrum, $A_{s}$, with only 5 out of 600 simulations exhibiting a dipole amplitude as large as that observed in the data. Interestingly, the dipole direction aligns closely with the known hemispherical power asymmetry, suggesting a potential link between these anomalies. All other cosmological parameters remain consistent with $\Lambda\mathrm{CDM}$ expectations. Our findings highlight the need to further investigate these anomalies and understand their nature and potential implications for better understanding of the early Universe.

A stellar mass black hole (BH) is believed to be formed as the result of the core collapse of a massive star at the end of its evolution. For a class of Gamma-Ray Bursts (GRBs), it is widely believed that their centre engines are just these stellar-mass BHs, which accrete the collapsing matter in hyper-accretion mode. In such systems, a popular scenario is that the magnetic field supported in the accretion disk extracts the rotational energy of the spinning BH and launch a jet on one hand, and the accretion of the infalling matter of the collapse will increase the BH's rotational energy on the other hand. However, the detailed physical processes of the above scenario are still not well understood. Here we report that when the accretion process is dominated by a Magnetically-Arrested-Disk (MAD), the above mentioned two competing processes link to each other, so that the spin evolution of the BH can be written in a simple form. Most interestingly, when the total accreted mass is enough, the BH spin will always reach to an equilibrium value peaked at $\chi\sim0.88$. This value does not depend on the initial mass and spin of the BH, as well as the history of accretion. This model predicts that there is a population of stellar-mass BH which possess a universal spin at the end of the collapsing accretion. We test this prediction against the 3rd gravitational wave (GW) catalogue (GWTC-3) and found that the distribution of the spin of the secondary BH is centred narrowly around $0.85\pm 0.05$ as predicted. Applying this model to the parameters of observed parameters in GWTC-3 and further GW catalogues, it is possible to infer the initial mass and spin distributions of the binary BHs detected with GW.

We study the physical properties of weak-lensing subhalos in the Coma cluster of galaxies using data from galaxy redshift surveys. The data include 12989 galaxies with measured spectroscopic redshifts (2184 from our MMT/Hectospec observation and 10807 from the literature). The $r$-band magnitude limit at which the differential spectroscopic completeness drops below 50% is 20.2 mag, which is spatially uniform in a region of 4.5 deg$^{2}$ where the weak-lensing map of Okabe et al. (2014) exists. We identify 1337 member galaxies in this field and use them to understand the nature of 32 subhalos detected in the weak-lensing analysis. We use Gaussian Mixture Modeling (GMM) in the line-of-sight velocity domain to measure the mean velocity, the velocity dispersion, and the number of subhalo galaxies by mitigating the contamination from the interloping galaxies. Using subhalo properties calculated with GMM, we find no significant difference in the redshift space distribution between the cluster member galaxies and subhalos. We find that the weak-lensing mass shows strong correlations with the number of subhalo member galaxies, velocity dispersion, and dynamical mass of subhalos with power-law slopes of $0.54^{+0.16}_{-0.15}$, $0.93^{+0.35}_{-0.32}$, and $0.50^{+0.31}_{-0.18}$, respectively. The slope of the mass--velocity dispersion relation of the weak-lensing subhalos appears shallower than that of the galaxy clusters, galaxy groups, and individual galaxies. These results suggest that the combination of redshift surveys with weak-lensing maps can be a powerful tool for better understanding the nature of subhalos in clusters.

Investigating the processes by which galaxies rapidly build up their stellar mass during the peak of their star formation ($z=2$--$3$) is crucial to advancing our understanding of the assembly of large-scale structures. We report the discovery of one of the most gas- and dust-rich protocluster core candidates, PJ0846+15 (J0846), from the Planck All-Sky Survey to Analyze Gravitationally lensed Extreme Starbursts (PASSAGES) sample. The exceedingly high total apparent star formation rate of up to ($\mu$SFR) $\sim 93600\,\mathrm{M}_\odot\,\text{yr}^{-1}$ is a result of a foreground cluster lens magnifying at least 11 dusty star-forming galaxies between $z=2.660$--$2.669$. Atacama Large Millimeter Array (ALMA) observations revealed 18 CO(3--2) emission-line detections, some of which are multiply-imaged systems, lensed by a foreground cluster at $z=0.77$. We present the first multi-wavelength characterization of this field, constructing a lens model that predicts that these 11 systems (magnification factor, $\mu\simeq1.5$--$25$) are contained within a projected physical extent of $280\times150$ kpc, with a velocity dispersion of $\sigma_{v}=246\pm72$ km s$^{-1}$ and a total intrinsic star formation rate of up to (SFR) $\sim10400\,\mathrm{M}_\odot\,\text{yr}^{-1}$. J0846 is one of the most unique, lensed, protocluster core candidates ever reported, and offers a magnified glimpse into the rapid buildup of massive local galaxy clusters.

In the standard planet formation scenario, planetesimals are assumed to form throughout the protoplanetary disk and to be smoothly distributed in the radial direction except for the snowline. Planetesimal growth has been investigated using this assumption, and the oligarchic growth model is widely accepted. However, recent simulations of gas and dust evolution have shown that planetesimals form only in radially limited locations -- such as at gas pressure bumps and snowlines -- and are concentrated in ring-like regions. When planetesimals are distributed in a ring-like region, scattered ones leak from the ring edge, resulting in planetesimal diffusion. To investigate protoplanet growth in expanding planetesimal rings, we perform a series of $\textit{ N}$-body simulations. In all the simulations, protoplanet growth is well explained by oligarchic growth, while the ring width expands due to planetesimal scattering by the protoplanets. Massive protoplanets tend to form near the ring center, and protoplanets that form far from the ring center are less massive than those in the center. The scaled orbital separations depend on neither the initial ring width nor on the total mass, and they are consistent with estimates based on the oligarchic growth model and the diffused planetesimal distribution. The width of the expanded planetesimal ring does not depend on its initial width, but it does depend on its total mass. The maximum mass of protoplanets depends strongly on the total ring mass and weakly on its initial width.

The detection of the neutrino magnetic moment (NMM,$\mu_v$) is one of the most significant challenges in physics. The additional energy loss due to NMM can significantly influence the He flash evolution in low-mass stars. Using the MESA code, we investigated the impact of NMM on the He flash evolution in low-mass stars. We found that NMM leads to an increase in both the critical He core mass required for the He flash and the luminosity of TRGB. For a typical $Z = 1 Z_{\odot}$ , $M$ = 1.0 $M_{\odot}$, and $\mu_v = 3 \times 10^{-12} \mu_{\mathrm{B}}$ model, the He core mass increases by $\sim 5\%$, and the TRGB luminosity increases by $\sim 35\%$ compared to the model without NMM. However, contrary to previous conclusions, our model indicates that the He flash occurs earlier, rather than delayed, with increasing NMM values. This is because the additional energy loss from NMM accelerates the contraction of the He core, releases more gravitational energy that heats the H shell and increases the hydrogen burning rate, thereby causing the He core to reach the critical mass faster and advancing the He flash. An increase in NMM results in a higher peak luminosity for the first He flash, a more off-center ignition position, and sub-flashes with higher luminosities, shorter intervals, and higher frequency. We found that the internal gravity wave (IGW) mixing generated by the He flash can induce sufficient mixing in the radiative zone, turning the overshoot region into a low-Dmix bottleneck within the stellar interior. The increase in NMM in the model narrows the overshoot bottleneck region, enabling Li to enter the surface convection zone more quickly, thereby enhancing the enrichment effect of IGW mixing on surface Li. For models incorporating both NMM and IGW mixing, the reduction in the overshoot bottleneck region allows them to effectively produce super Li-rich red clump star samples.

We carry out an unprecedented high-resolution simulation for the solar convection zone. Our calculation reproduces the fast equator and near-surface shear layer (NSSL) of differential rotation and the near-surface poleward meridional flow simultaneously. The NSSL is located in a complex layer where the spatial and time scales of thermal convection are significantly small compared with the deep convection zone. While there have been several attempts to reproduce the NSSL in numerical simulation, the results are still far from reality. In this study, we succeed in reproducing an NSSL in our new calculation. Our analyses lead to a deeper understanding of the construction mechanism of the NSSL, which is summarized as: 1) rotationally unconstrained convection in the near-surface layer transports the angular momentum radially inward; 2) sheared poleward meridional flow around the top boundary is constructed; 3) the shear causes a positive kinetic $\langle v'_r v'_\theta\rangle$ and negative magnetic $\langle B_r B_\theta\rangle$ correlations; and 4) the turbulent viscosity and magnetic tension are latitudinally balanced with the Coriolis force in the NSSL. We emphasize the importance of the magnetic field in the solar convection zone.

The central engine of blazar OJ~287 is arguably the most notable supermassive black hole (SMBH) binary candidate that emits nano-Hertz (nHz) gravitational waves. This inference is mainly due to our ability to predict and successfully monitor certain quasi-periodic doubly peaked high brightness flares with a period of $\sim$12 years from this blazer. The use of post-Newtonian accurate SMBH binary orbital description that includes the effects of higher order GW emission turned out to be a crucial ingredient for accurately predicting the epochs of such Bremsstrahlung flares in our SMBH binary central engine description for OJ~287. It was very recently argued that one should include the effects of dynamical friction, induced by certain dark matter density spikes around the primary SMBH, to explain the {\it observed} decay of SMBH binary orbit in OJ~287. Invoking binary pulsar timing-based arguments, measurements, and OJ~287's orbital description, we show that observationally relevant SMBH binary orbital dynamics in OJ~287 are insensitive to dark matter-induced dynamical friction effects. This implies that we could only provide an upper bound on the spike index parameter rather than obtaining an observationally derived value, as argued by \cite{Chan2024}.

Primordial Black Holes (PBHs) may have formed in the early Universe due to the collapse of super-horizon curvature fluctuations. Simulations of PBH formation have been essential for inferring the initial conditions that lead to black hole formation and for studying their properties and impact on our Universe. The Misner-Sharp formalism is commonly used as a standard approach for these simulations. Recently, type-II fluctuations, characterized by a non-monotonic areal radius, have gained interest. In the standard Misner-Sharp approach for simulating PBH formation with these fluctuations, the evolution equations suffer from divergent terms (0/0), which complicate and prevent the simulations. We formulate a new approach to overcome this issue in a simple manner by using the trace of the extrinsic curvature as an auxiliary variable, allowing simulations of type-II fluctuations within the Misner-Sharp formalism. Using a set of standard exponential-shaped curvature profiles, we apply our new approach and numerical code based on pseudospectral methods to study the time evolution of the gravitational collapse, threshold values of type A/B PBHs and PBH mass. Interestingly, we identify cases of type-II fluctuations that do not necessarily result in PBH formation.

We numerically simulate the formation of Primordial Black Holes (PBHs) in a radiation-dominated Universe under the assumption of spherical symmetry, driven by the collapse of adiabatic fluctuations, for different curvature profiles $\zeta$. Our results show that the threshold for PBH formation, defined as the peak value of the critical compaction function $\mathcal{C}_{c}(r_m)$ (where $r_m$ is the scale at which the peak occurs), does not asymptotically saturate to its maximum possible value in the type-I region for sufficiently sharp profiles. Instead, the threshold is found in the type-II region with $\mathcal{C}_{c}(r_m)$ being a minimum. We find, for the cases tested, that this is a general trend associated with profiles that exhibit extremely large curvatures in the linear component of the compaction function $\mathcal{C}_{l}(r) \equiv -4r \zeta'(r)/3$ shape around its peak $r_m$ (spiky shapes). To measure this curvature at $r_m$, we define a dimensionless parameter: $\kappa \equiv -r^{2}_m \mathcal{C}_l''(r_m)$, and we find that the thresholds observed in the type-II region occur for $\kappa \gtrsim 30$ for the profiles we have used. By defining the threshold in terms of $\mathcal{C}_{l,c}(r_m)$, we extend previous analytical estimations to the type-II region, which is shown to be accurate within a few percent when compared to the numerical simulations for the tested profiles. Our results suggest that current PBH abundance calculations for models where the threshold lies in the type-II region may have been overestimated due to the general assumption that it should saturate at the boundary between the type-I and type-II regions.

We analyze three nearby spiral galaxies - NGC 1097, NGC 1566, and NGC 3627 - using images from the DustPedia database in seven infrared bands (3.6, 8, 24, 70, 100, 160, and 250 micron). For each image, we perform photometric decomposition and construct a multi-component model, including a detailed representation of the spiral arms. Our results show that the light distribution is well described by an exponential disk and a Sersic bulge when non-axisymmetric components are properly taken into account. We test the predictions of the stationary density wave theory using the derived models in bands, tracing both old stars and recent star formation. Our findings suggest that the spiral arms in all three galaxies are unlikely to originate from stationary density waves. Additionally, we perform spectral energy distribution (SED) modeling using the hierarchical Bayesian code HerBIE, fitting individual components to derive dust properties. We find that spiral arms contain a significant (>10%) fraction of cold dust, with an average temperature of approximately 18-20 K. The estimated fraction of polycyclic aromatic hydrocarbons (PAHs) declines significantly toward the galactic center but remains similar between the arm and interarm regions.

The interplay between radiative diffusion, rotation, convection, and magnetism in metallic-line chemically peculiar stars is still not fully understood. Recently, evidence has emerged that these effects can work together. Our goal is to study the bright binary system 50 Dra, describe its orbit and components, and study additional variability. We conducted our analysis using TESS short-cadence data and new high-resolution spectroscopic observations. We disentangled the spectra using Korel and performed spectral synthesis with Atlas9 and Synthe codes. The system was modelled using Korel and Phoebe2.4. We also employed SED fitting in Ariadne and isochrone fitting using Param1.5 codes. Our findings indicate that the non-eclipsing system (with an inclination of 49.9(8) deg) 50 Dra, displaying ellipsoidal brightness variations, consists of two nearly equal A-type stars with masses of $M_{1}=2.08(8)$ and $M_{2}=1.97(8)$ M$_{\odot}$ and temperatures of 9800(100) and 9200(200) K, respectively. Our analysis also suggests that the system, with an orbital period of $P_{\rm orb}=4.117719(2)$ days, is tidally relaxed with a circular orbit and synchronous rotation of the components. Furthermore, we discovered that both stars are metallic-line Am chemically peculiar stars with an underabundance of Sc and an overabundance of iron-peak and rare-earth elements. We identified additional variations with slightly higher frequency than the rotational frequency of the components that we interpret as prograde g-mode pulsations. The system 50 Dra exhibits numerous exciting phenomena that co-exist together and may have an impact on our understanding of chemical peculiarity and pulsations.

Type Ia supernovae (SNeIa), the thermonuclear explosions of C/O white dwarf stars in binary systems, are phenomena that remain poorly understood. The complexity of their progenitor systems, explosion physics and intrinsic diversity poses not only challenges for their understanding as astrophysical objects, but also for their standardization and use as cosmological probes. Near-infrared (NIR) observations offer a promising avenue for studying the physics of SNeIa and for reducing systematic uncertainties in distance estimations, as they exhibit lower dust extinction and smaller dispersion in peak luminosity than optical bands. Here, Principal Component Analysis (PCA) is applied to a sample of SNeIa with well-sampled NIR (YJH-band) light curves to identify the dominant components of their variability and constrain physical underlying properties. The theoretical models of Kasen2006 are used for the physical interpretation of the PCA components, where we found the 56Ni mass to describe the dominant variability. Other factors, such as mixing and metallicity, were found to contribute significantly as well. However, some differences are found between the components of the NIR bands which may be attributed to differences in the explosion aspects they each trace. Additionally, the PCA components are compared to various light-curve parameters, identifying strong correlations between some components and peak brightness in both the NIR and optical bands, particularly in the Y band. When applying PCA to NIR color curves, we found interesting correlations with the host-galaxy mass, where SNeIa with redder NIR colors are predominantly found in less massive galaxies. We also investigate the potential for improved standardization in the Y band by incorporating PCA coefficients as correction parameters, leading to a reduction in the scatter of the intrinsic luminosity of SNeIa.

We report the detection of a potential quasi-periodic signal with a period of $\sim2$ years in the blazar ON 246, based on Fermi-LAT ($\gamma$-rays) and ASAS-SN (optical) observations spanning 11.5 years (MJD 55932-60081). We applied various techniques to investigate periodic signatures in the light curves, including the Lomb-Scargle periodogram (LSP), Weighted Wavelet Z-transform (WWZ), and REDFIT. The significance of the signals detected in LSP and WWZ was assessed using two independent approaches: Monte Carlo simulations and red noise modeling. Our analysis revealed a dominant peak in the $\gamma$-ray and optical light curves, with a significance level exceeding 3$\sigma$ in both LSP and WWZ, consistently persisting throughout the observation period. Additionally, the REDFIT analysis confirmed the presence of a quasi-periodic signal at $\sim$0.00134 $day^{-1}$ with a 99% confidence threshold. To explain the observed quasi-periodic variations in $\gamma$-ray and optical emissions, we explored various potential physical mechanisms. Our analysis suggests that the detected periodicity could originate from a supermassive binary black hole (SMBBH) system or the jet-induced orbital motion within such a system. Based on variability characteristics, we estimated the black hole mass of ON 246. The study suggests that the mass lies within the range of approximately $(0.142 - 8.22) \times 10^9 \ M_{\odot}$.

2003fg-like Type Ia supernovae (03fg-like SNe Ia) are a rare subtype of SNe Ia, photometrically characterized by broader optical light curves and bluer ultraviolet (UV) colors compared to normal SNe Ia. In this work, we study four 03fg-like SNe Ia using Swift UltraViolet and Optical Telescope (UVOT) grism observations to understand their unique UV properties and progenitor scenario(s). We report 03fg-like SNe Ia to have similar UV features and elemental compositions as normal SNe Ia, but with higher UV flux relative to optical. Previous studies have suggested that the UV flux levels of normal SNe Ia could be influenced by their progenitor properties, such as metallicity, with metal-poor progenitors producing higher UV flux levels. While 03fg-like SNe were previously reported to occur in low-mass and metal-poor host environments, our analysis indicates that their UV excess cannot be explained by their host-galaxy parameters. Instead, we demonstrate that the addition of a hot blackbody component, likely arising from the interaction with the circumstellar material (CSM), to the normal SN Ia spectrum, can reproduce their distinctive UV excess. This supports the hypothesis that 03fg-like SNe Ia could explode in a CSM-rich environment.

In this work, we explore primordial black holes (PBH) formation scenario during the post-inflationary preheating stage dominated by the inflaton field. We consider, in particular, a model-independent parametrization of the Gaussian peak inflationary power spectrum that leads to amplified inflationary density fluctuations before the end of inflation. These modes can reenter the horizon during preheating and could experience instabilities that trigger the production of PBH. This is estimated with the Khlopov-Polnarev (KP) formalism that takes into account non-spherical effects. We derive an accurate analytical expression for the mass fraction under the KP formalism that fits well with the numerical evaluation. Particularly, we focus on ultra-light PBH of masses $M_{\text{PBH}}<10^9g$ and study their evolution and (possible) dominance after the decay of the inflation field into radiation and before the PBH evaporation via Hawking radiation. These considerations alter the previous estimates of induced gravitational waves (GWs) from PBH dominance and open new windows for detecting stochastic GW backgrounds with future detectors.

One of hot topics in the solar physics are the so-called 'stealth' coronal mass ejections (CME), which are not associated with any appreciable energy release events in the lower corona, such as the solar flares. It is sometimes assumed that these phenomena might be produced by some specific physical mechanism, but no particular suggestions were put forward. It is the aim of the present paper to show that a promising explanation of the stealth CMEs can be based on the so-called 'topological' ignition of the magnetic reconnection. As a theoretical basis, we employ the Gorbachev-Kel'ner-Somov-Shvarts (GKSS) model of formation of the magnetic null point, which is produced by a specific superposition of the remote sources (sunspots) rather than by the local current systems. As follows from our numerical simulations, the topological model explains very well all basic features of the stealth CMEs: (i) the plasma eruption develops without an appreciable heat release from the spot of reconnection, i.e., without the solar flare; (ii) the spot of reconnection (magnetic null point) can be formed far away from the location of the magnetic field sources; (iii) the trajectories of eruption are strongly curved, which can explain observability of CMEs generated behind the solar limb. Therefore, the topological ignition of magnetic reconnection should be interesting both by itself, as a novel physical phenomenon, and as a prognostic tool for forecasting the stealth CMEs and the resulting unexpected geomagnetic storms.

We present a comprehensive analysis of Cyg X-1, utilizing archival high-resolution UV and optical spectra in conjunction with sophisticated atmospheric models. Notably, this is the first investigation to simultaneously analyze UV and optical spectra of Cyg X-1 along with incorporating X-rays to constrain the stellar and wind parameters. Our analysis yields notably lower masses for both the donor (29$\,M_\odot$) and the black hole (12.7 to 17.8$\,M_\odot$, depending on inclination), and confirms that the donor's radius is close to reaching the inner Lagrangian point. We find super-solar Fe, Si, and Mg abundances (1.3-1.8 times solar) at the surface of the donor star, while the total CNO abundance remains solar despite evidence of CNO processing (N enrichment, O depletion) and He enrichment. This abundance pattern is distinct from the surrounding Cyg OB3 association. We observe a clear difference in wind parameters between X-ray states: $v_\infty \approx 1200\,\mathrm{km\,s}^{-1}$ and $\dot{M} \approx 3\times 10^{-7}\,M_\odot\,\mathrm{yr}^{-1}$ in the high/soft state, increasing to $v_\infty\lesssim 1800\,\mathrm{km\,s}^{-1}$ and $\dot{M}\lesssim 5\times 10^{-7}\,M_\odot\,\mathrm{yr}^{-1}$ in the low/hard state. The observed X-ray luminosity is consistent with wind-fed accretion. Evolutionary models show that Cyg X-1 will undergo Roche lobe overflow in the near future. Under a fully conservative mass accretion scenario, our models predict a future binary black hole merger for Cyg X-1 within $\sim5$ Gyr. Our comprehensive analysis provides refined stellar and wind parameters of the donor star in Cyg X-1, highlighting the importance of using advanced atmospheric models and considering X-ray ionization and wind clumping. The observed abundances suggest a complex formation history involving a high initial metallicity.

We designed customized Lyman-break color selection techniques to identify galaxy candidates in the redshift ranges $15 \leq z \leq 20$ and $20 \leq z \leq 28$. The selection was performed on the ASTRODEEP-JWST multi-band catalogs of the CEERS, Abell-2744, JADES, NGDEEP, and PRIMER survey fields, covering a total area of $\sim0.2$ sq. deg. We identify nine candidates at $15 \leq z \leq 20$, while no objects are found based on the $z\gtrsim20$ color selection criteria. Despite exhibiting a $>$1.5 mag break, all the objects display multimodal redshift probability distributions across different SED-fitting codes and methodologies. The alternative solutions correspond to poorly understood populations of low-mass quiescent or dusty galaxies at z$\sim$3-7. This conclusion is supported by the analysis of a NIRSpec spectrum recently acquired by the CAPERS program for one interloper object, which is confirmed to be a dusty ($E(B-V)=0.8$ mag) starburst galaxy at $z=6.56$. We measured the UV luminosity function under different assumptions on the contamination level within our sample. We find that if even a fraction of the candidates is indeed at $z\gtrsim15$, the resulting UV LF points to a very mild evolution compared to estimates at $z<15$, implying a significant tension with existing theoretical models. In particular, confirming our bright ($M_{\text{UV}}<-21$) candidates would require substantial revisions to the theoretical framework. In turn, if all these candidates will be confirmed to be interlopers, we conclude that future surveys may need ten times wider areas to select $M_{\text{UV}}\lesssim-20$ galaxies at $z>15$. Observations in the F150W and F200W filters at depths comparable to those in the NIRCam LW bands are also required to mitigate contamination from rare red objects at z$\lesssim$8.

The Hamilton-Jacobi approach is a powerful tool to describe super-Hubble dynamics during cosmological inflation in a non-linear way. A key assumption of this framework is to neglect anisotropic perturbations on large scales. We show that neglecting the anisotropic sector in the momentum constraint corresponds to discarding the non-adiabatic mode of scalar-field perturbations at large scales. Consequently, the Hamilton-Jacobi approach cannot be used to describe the evolution of large-scale perturbations during inflation beyond slow roll, when non-adiabatic fluctuations play an important role on super-Hubble scales due to the absence of an attractor trajectory. As an example, we analyse the case of cosmological perturbations during a phase of ultra-slow-roll inflation.

It is well-known that the global acoustic oscillations of the Sun's atmosphere can excite resonance modes within large-scale magnetic concentrations. These structures are conduits of energy between the different layers of the solar atmosphere, and understanding their dynamics can explain the processes behind coronal heating and solar wind acceleration. In this work, we studied the Doppler velocity spectrum of more than a thousand large-scale magnetic structures (i.e., sunspots) in the solar photosphere that crossed near the disk centre of the Sun. We exploited the excellent stability and seeing-free conditions of the Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO) to cover nearly seven years of observations, providing the most comprehensive statistical analysis of its kind. Here, we show that the power spectra of the umbra of sunspots in the photosphere is remarkably different from the one of quiet-Sun regions, with both exhibiting a primary peak at 3.3 mHz, but the sunspot umbrae also displaying a closely packed series of secondary peaks in the $4-6$~mHz band. Understanding the origin of such peaks is a challenging task. Here, we explore several possible explanations for the observed oscillations, all pointing toward a potential resonant interaction within these structures and an unknown driver. Our observational result provides further insight into the magnetic connectivity between the different layers of the dynamic atmosphere of the Sun.

We present the analysis of Ly$\alpha$ haloes around faint quasars at $z\sim4$ and $z\sim6$. We use 20 and 162 quasars at $z\sim4$ and $z\sim6$, taken by slit spectroscopy, and detect Ly$\alpha$ haloes around 12 and 26 of these quasars, respectively. The average absolute magnitudes of the detected quasars are $\langle M_{1450} \rangle = -23.84$ mag at $z\sim4$ and $\langle M_{1450} \rangle = -23.68$ mag at $z\sim6$, which are comparable at $z\sim4$ and 3 mag fainter at $z\sim6$ than those of previous studies. The median surface brightness profiles are found to be consistent with an exponential curve, showing a hint of flattening within a radius of 5 kpc. The Ly$\alpha$ haloes around these faint quasars are systematically fainter than those around bright quasars in the previous studies. We confirm the previous results that the Ly$\alpha$ halo luminosity depends on both the ionizing and Ly$\alpha$ peak luminosities of quasars at $z\sim4$, and also find that a similar correlation holds even at $z\sim6$. While the observed Ly$\alpha$ halo luminosity is overall attributed to recombination emission from the optically thin gas clouds in the CGM, its luminosity dependences can be consistently explained by the partial contributions of recombination radiation from the optically thick clouds, which is thought to originate from the CGM centre, and the scattered Ly$\alpha$ photons, which is resonantly trapped at the CGM centre and escaping outside of the haloes.

The early start to life naively suggests that abiogenesis is a rapid process on Earth-like planets. However, if evolution typically takes ~4Gyr to produce intelligent life-forms like us, then the limited lifespan of Earth's biosphere (~5-6Gyr) necessitates an early (and possibly highly atypical) start to our emergence - an example of the weak anthropic principle. Our previously proposed objective Bayesian analysis of Earth's chronology culminated in a formula for the minimum odds ratio between the fast and slow abiogenesis scenarios (relative to Earth's lifespan). Timing from microfossils (3.7Gya) yields 3:1 odds in favor of rapid abiogenesis, whereas evidence from carbon isotopes (4.1Gya) gives 9:1, both below the canonical threshold of "strong evidence" (10:1). However, the recent result of a 4.2Gya LUCA pushes the odds over the threshold for the first time (nominally 13:1). In fact, the odds ratio is >10:1 for all possible values of the biosphere's ultimate lifespan and speculative hypotheses of ancient civilizations. For the first time, we have formally strong evidence that favors the hypothesis that life rapidly emerges in Earth-like conditions (although such environments may themselves be rare).

In the last decade, the available measurements of fluorine abundance have increased significantly, providing additional information on the chemical evolution of our Galaxy and details on complex stellar nucleosynthesis processes. However, the observational challenges to obtain stellar F abundances favor samples with higher metallicities, resulting in a scarcity of measurements at low-metallicity ([Fe/H] $<-2.0$). We present F abundances and upper limits in 7 carbon enhanced metal-poor (CEMP) stars observed with the Immersion Grating Infrared Spectrometer (IGRINS), at the Gemini-South telescope. These new observations delivered high-resolution, high signal-to-noise ratio, infrared spectra allowing us to probe significantly deeper into the metal-poor regime and the cosmic origin of F. This work presents the results of our observations, including two 2-sigma detections and five upper limits in a variety of CEMP stars. Arguably the most important result is for CS 29498-0043, a CEMP-no star at [Fe/H] = $-3.87$ with a F detection of [F/Fe] = $+2.0\pm 0.4$, the lowest metallicity star (more than a factor of 10 lower in metallicity than the next detection) with observed F abundance to date. This measurement allowed us to differentiate between two zero metallicity Population III (Pop III) progenitors: one involving He-burning with primary N in Wolf-Rayet stars, and the other suggesting H-burning during hypernova explosions. Our measured value is in better agreement with the latter scenario. This detection represents a pilot, and pioneering study demonstrating the power of F to explore the nature and properties of the first chemical enrichment from Pop III stars.

We report the results of a comprehensive analysis of the multiwavelength (in optical and X-rays) and multitimescale (from months to tenths of a second) variability of the 2018-2020 outburst of the black hole transient MAXI J1820+070. During the first outburst episode, a detailed analysis of the optical photometry shows a periodicity that evolves over time and stabilises at a frequency of $1.4517(1)$ $1/d$ ($\sim0.5\%$ longer than the orbital period). This super-orbital modulation is also seen in the X-rays for a few days soon after the transition to the high-soft state. We also observed optical Quasi-Periodic Oscillations (QPOs), which correspond to some of the QPOs observed in X-rays at three different epochs when the source was in the low-hard state. In two epochs, optical QPOs with a centroid consistent with half the frequency of the most prominent X-ray QPO can be seen. If the lowest modulation frequency is the one observed in the optical, the characteristic precession frequency of MAXI J1820+070 is lower than that inferred from the `fundamental' QPO in the X-rays. Assuming that QPOs can be generated by Lense-Thirring precession, we calculate the spin of the black hole in the case where the fundamental precession frequency is tracked by the optical emission. We find a relatively slowly spinning black hole with a spin parameter $\lesssim 0.15$. The super-orbital optical and X-ray modulations observed after the disappearance of the QPOs may be triggered by the self-irradiation of the outer disc by a standard inner disc truncated at a few gravitational radii.

Starobinsky inflation and non-minimally coupled Higgs inflation have been among the most favored models of the early universe, as their predictions for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$ fall comfortably within the constraints set by Planck and BICEP/Keck. However, new results from the Atacama Cosmology Telescope (ACT) suggest a preference for higher values of $n_s$, introducing tension with the simplest realizations of these models. In this work, being agnostic about the nature of the inflaton, we show that incorporating one-loop corrections to a Higgs-like inflationary scenario leads to a shift in the predicted value of $n_s$, which brings Higgs-like inflation into better agreement with ACT observations. Remarkably, we find that this can be achieved with non-minimal couplings $\xi < 1$, in contrast to the large values typically required in conventional Higgs inflation, thereby pushing any unitarity-violation scale above the Planck scale. The effect is even more significant when the model is formulated in the Palatini approach, where the modified field-space structure naturally enhances deviations from the metric case. These findings highlight the importance of quantum corrections and gravitational degrees of freedom in refining inflationary predictions in light of new data.

Complex Organic Molecules (COMs) in the form of prebiotic molecules are potentially building blocks of life. Using Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 observations in spectral scanning mode, we carried out a deep search for COMs within the disk of V883 Ori, covering frequency ranges of $\sim$ 348 - 366 GHz. V883 Ori is an FUor object currently undergoing an accretion burst, which increases its luminosity and consequently increases the temperature of the surrounding protoplanetary disk, facilitating the detection of COMs in the gas phase. We identified 26 molecules, including 14 COMs and 12 other molecules, with first detection in this source of the molecules: CH3OD, H2C17O, and H213CO. We searched for multiple nitrogen-bearing COMs, as CH3CN had been the only nitrogen-bearing COM that has been identified so far in this source. We also detected CH3CN, and tentatively detect CH3CH2CN, CH2CHCN, CH3OCN, CH3NCO, and NH2CHO. We compared the abundances relative to CH3OH with those in the handful of objects with previous detections of these species: the Class 0 protostars IRAS 16293-2422 A, IRAS 16293-2422 B and B1-c, the high-mass star-forming region Sagittarius B2 (North), the Solar System comet 67P/Churyumov-Gerasimenko, and the protoplanetary disk of Oph-IRS 48. We report $\sim$ 1 to 3 orders of magnitude higher abundances compared to Class 0 protostars and $\sim$ 1 to 3 orders of magnitude lower abundances compared to the protoplanetary disk, Sagittarius B2 (North), and 67P/C-G. These results indicate that the protoplanetary disk phase could contribute to build up of COMs.

We performed simultaneous V band photometry and spectroscopic observations of the recurrent nova T CrB and estimate the V band magnitude of the red giant. We find for the red giant of T CrB apparent and absolute V-band magnitudes m_V = 10.17 +/- 0.06 and M_V = +0.14 +/- 0.08, respectively. At the maximum of the ellipsoidal variation when these values are obtained, its absolute V-band magnitude is similar but fainter than the typical M4/5III giants. The data are available on : this http URL

de Grijs and Bono (ApJS 2020, 246, 3) compiled a list of distances to M87 from the literature published in the last 100 years. They reported the arithmetic mean of the three most stable tracers (Cepheids, tip of the red giant branch, and surface brightness fluctuations). The arithmetic mean is one of the measures of central tendency of a distribution; others are the median and mode. The three do not align for asymmetric distributions, which is the case for the distance moduli $\mu_0$ to M87. I construct a kernel density distribution of the set of $\mu_0$ and estimate the recommended distance to M87 as its mode, obtaining $\mu_0 = \left(31.06~\pm~0.001\,\textrm{(statistical)}\,^{+0.04}_{-0.06}\,\textrm{(systematic)}\right)$~mag, corresponding to \linebreak $D=16.29^{+0.30}_{-0.45}$~Mpc, which yields uncertainties smaller than those associated with the mean and median.

Changing-look quasars challenge many models of the quasar central engine. Their extreme variability in both the continuum and broad emission-line fluxes on timescales on the order of years is difficult to explain. To investigate the cause of the observed transitions, we present new contemporaneous optical and X-ray observations of three faded changing-look quasars as they return to the high state. Two of these three faded changing-look quasars remained in a quiescent state for more than ten years before returning to a new high state. We find that before, during, and after transition, the spectral energy distributions of all three follow predictions for quasars based on X-ray binary outbursts, suggesting that the mechanism for the change is likely a changing accretion rate causing changes in the accretion flow structure. We also find that, in two of the three cases, the transition between the initial high and low state and the transition between the low and new high state took nearly identical amounts of time, on the order of hundreds of days. This transition timescale is useful for testing theoretical models that attempt to explain the short time scale for the state transition.

We investigated the initiation and the evolution of an X7.1-class solar flare observed in solar active region NOAA 13842 on October 1, 2024, based on a data-constrained magnetohydrodynamic (MHD) simulation. The nonlinear force-free field (NLFFF) extrapolated from the photospheric magnetic field about 1 hour before the flare was used as the initial condition for the MHD simulations. The NLFFF reproduces highly sheared field lines that undergo tether-cutting reconnection in the MHD simulation, leading to the formation of a highly twisted magnetic flux rope (MFR), which then erupts rapidly driven by both torus instability and magnetic reconnection. This paper focuses on the dynamics of the MFR and its role in eruptions. We find that magnetic reconnection in the pre-eruption phase is crucial in the subsequent eruption driven by the torus instability. Furthermore, our simulation indicates that magnetic reconnection also directly enhances the torus instability. These results suggest that magnetic reconnection is not just a byproduct of the eruption due to reconnecting of post-flare arcade, but also plays a significant role in accelerating the MFR during the eruption.

Fossil magnetic fields of early-type stars are typically characterised by symmetric or slightly distorted oblique dipolar surface geometries. Contrary to this trend, the late-B magnetic chemically peculiar star HD 57372 exhibits an unusually large rotational variation of its mean magnetic field modulus, suggesting a highly atypical field configuration. In this study, we present a Zeeman Doppler imaging analysis of HD 57372, revealing an exceptionally asymmetric bipolar magnetic topology, rarely observed in early-type stars. According to our magnetic field maps, reconstructed from the intensity and circular polarisation profiles of Fe, Cr, and Ti lines, approximately 66 per cent of the stellar surface is covered by a diffuse outward-directed radial field, with local field strengths reaching 11.6 kG, while the remaining 34 per cent hosts a highly concentrated inward-directed field with a strong horizontal component and a peak strength of 17.8 kG. These unusual surface magnetic field characteristics make HD 57372 a notable object for testing fossil-field theories and interpreting phase-resolved spectropolarimetric observations of early-type stars.

We investigate whether dark energy deviates from the cosmological constant ($\Lambda$CDM) by analyzing baryon acoustic oscillation (BAO) measurements from the Data Release 1 (DR1) and Data Release 2 (DR2) of DESI observations, in combination with Type Ia supernovae (SNe) and cosmic microwave background (CMB) distance information. We find that with the larger statistical power and wider redshift coverage of the DR2 dataset the preference for dynamical dark energy does not decrease and remains at approximately the same statistical significance as for DESI~DR1. Employing both a shape-function reconstruction and non-parametric methods with a correlation prior derived from Horndeski theory, we consistently find that the dark energy equation of state $w(z)$ evolves with redshift. While DESI DR1 and DR2 BAO data alone provide modest constraints, combining them with independent SNe samples (PantheonPlus, Union3, and the DES 5-year survey) and a CMB distance prior strengthens the evidence for dynamical dark energy. Bayesian model-selection tests show moderate support for dark energy dynamics when multiple degrees of freedom in $w(z)$ are allowed, pointing to increasing tension with $\Lambda$CDM at a level of roughly $3\sigma$ (or more in certain data combinations). Although the methodology adopted in this work is different from those used in companion DESI papers, we find consistent results, demonstrating the complementarity of dark energy studies performed by the DESI collaboration. Although possible systematic effects must be carefully considered, it currently seems implausible that $\Lambda$CDM will be rescued by future high-precision surveys, such as the complete DESI, Euclid, and next-generation CMB experiments. These results therefore highlight the possibility of new physics driving cosmic acceleration and motivate further investigation into dynamical dark energy models.

We analyse the transport of cosmic rays (CR) in magnetic fields that are structured on scales greater than the CR Larmor radius. We solve the Vlasov-Fokker-Planck (VFP) equation for various mixes of mirroring and small-angle scattering and show that relatively small deviations from a uniform magnetic field can induce mirroring and inhibit CR transport to levels that mimic Bohm diffusion in which the CR mean free path is comparable with the CR Larmor radius. Our calculations suggest that shocks may accelerate CR to the Hillas (1984) energy without the need for magnetic field amplification on the Larmor scale. This re-opens the possibility, subject to more comprehensive simulations, that young supernova remnants may be accelerating CR to PeV energies, and maybe even to higher energies beyond the knee in the energy spectrum. We limit our discussion of CR acceleration to shocks that are non-relativistic.

We present a multi-wavelength study of an extended area hosting the bubble N59-North to explore the physical processes driving massive star formation (MSF). The Spitzer 8 $\mu$m image reveals an elongated/filamentary infrared-dark cloud (length $\sim$28 pc) associated with N59-North, which contains several protostars and seven ATLASGAL dust clumps at the same distance. The existence of this filament is confirmed through $^{13}$CO and NH$_3$ molecular line data in a velocity range of [95, 106] km s$^{-1}$. All dust clumps satisfy Kauffmann & Pillai's condition for MSF. Using Spitzer 8 $\mu$m image, a new embedded hub-filament system candidate (C-HFS) is investigated toward the ATLASGAL clump, located near the filament's central region. MeerKAT 1.3 GHz continuum emission, detected for the first time toward C-HFS, reveals an ultracompact HII region driven by a B2-type star, suggesting an early stage of HFS with minimal feedback from the young massive star. The comparison of the position-velocity (PV) and position-position-velocity (PPV) diagrams with existing theoretical models suggests that rotation, central collapse, and end-dominated collapse are not responsible for the observed gas motion in the filament. The PPV diagram indicates the expansion of N59-North by revealing blue- and red-shifted gas velocities at the edge of the bubble. Based on comparisons with magnetohydrodynamic simulations, this study suggests that cloud-cloud collision (CCC) led to the formation of the filament, likely giving it a conical structure with gas converging toward its central region, where C-HFS is located. Overall, the study supports multi-scale filamentary mass accretion for MSF, likely triggered by CCC.

Properly estimating correlations between objects at different spatial scales necessitates $\mathcal{O}(n^2)$ distance calculations. For this reason, most widely adopted packages for estimating correlations use clustering algorithms to approximate local trends. However, methods for quantifying the error introduced by this clustering have been understudied. In response, we present an algorithm for estimating correlations that is probabilistic in the way that it clusters objects, enabling us to quantify the uncertainty caused by clustering simply through model inference. These soft clustering assignments enable correlation estimators that are theoretically differentiable with respect to their input catalogs. Thus, we also build a theoretical framework for differentiable correlation functions and describe their utility in comparison to existing surrogate models. Notably, we find that repeated normalization and distance function calls slow gradient calculations and that sparse Jacobians destabilize precision, pointing towards either approximate or surrogate methods as a necessary solution to exact gradients from correlation functions. To that end, we close with a discussion of surrogate models as proxies for correlation functions. We provide an example that demonstrates the efficacy of surrogate models to enable gradient-based optimization of astrophysical model parameters, successfully minimizing a correlation function output. Our numerical experiments cover science cases across cosmology, from point spread function (PSF) modeling efforts to gravitational simulations to galaxy intrinsic alignment (IA).

While the simplest inflationary models predict a power-law form of the primordial power spectrum (PPS), various UV complete scenarios predict features on top of the standard power law that leave characteristic imprints in the late-time distribution of matter, encoded in the galaxy power spectrum. In this work, we assess the validity of the Effective Field Theory of Large Scale Structure (EFTofLSS) and the IR-resummation scheme of PyBird in the context of primordial (oscillatory) features. We find an excellent agreement at the level of the matter power spectrum between N-body simulations and the one-loop EFT predictions, for models commonly studied in the literature. We then apply the EFTofLSS to the galaxy power spectrum measurements from BOSS LRG and eBOSS QSO to constrain specific global and local features in the PPS. We demonstrate that while such features can improve the fit to cosmic microwave background (CMB) data, they may result in a poorer fit to clustering measurements at low redshift. The resulting constraints on the amplitude of the primordial oscillations are competitive with those obtained from CMB data, despite the well-known damping of oscillations due to non-linear structure formation processes. For the first time in this context, we jointly analyze the galaxy power spectrum (monopole and quadrupole) in combination with Planck CMB data to derive strong constraints on the amplitude of primordial features. This work highlights the EFTofLSS as a powerful tool for testing early universe scenarios on scales that complement CMB observations.

We present SOFIA/upGREAT velocity-resolved spectral imaging and analysis of the 158 um [C II] spectral line toward the central 80 by 43\,pc region of the Central Molecular Zone of the Galaxy. The field we imaged with 14" (0.6 pc) spatial and 1 km/s spectral resolution contains the Circum-Nuclear Disk (CND) around the central black hole Sgr A*, the neighboring thermal Arched Filaments, the nonthermal filaments of the Radio Arc, and the three luminous central star clusters. [C II] traces emission from the CND's inner edge to material orbiting at a distance of approximately 6 pc. Its velocity field reveals no sign of inflowing material nor interaction with winds from the Sgr A East supernova remnant. Wide-field imaging of the Sgr A region shows multiple circular segments, including the thermal Arched Filaments, that are centered on a region that includes the Quintuplet cluster. We examine the possibility that the Arched Filaments and other large-scale arcs trace transient excitation events from supernova blast waves. Along the Arched Filaments, comparisons among far-IR fine structure lines show changes in ionization state over small scales and that high-excitation lines are systematically shifted in position from the other lines. These also point to transient fast winds that shocked on the surface of the Arches cloud to produce additional local UV radiation to excite the Arched Filaments on a cloud surface illuminated by UV from hot stars.

Radio transients, such as pulsars and Fast Radio Bursts (FRBs), are primarily detected at centimetre radio wavelengths, where higher luminosities are found. However, observations of sources in dense environments are heavily affected by propagation effects which may hinder a detection. Millimetre wave observations bypass this complication but require the largest radio telescopes to compensate for the lower flux densities. When used in phased mode, the ALMA radio telescope provides an equivalent dish size of 84m, being the most sensitive instrument at mm/sub mm. With its high time resolution it offers a unique opportunity to study radio transients in an unexplored window. We study the Galactic Centre (GC) magnetar, PSR J1745$-$2900, as a laboratory for magnetars in complex magneto-turbulent environments and to link with FRBs. We showcase the potential of ALMA in phased mode to observe radio transients and to achieve, for some sources, the first ever detections outside the cm wave range. We studied the GC magnetar using ALMA archival data of Sgr A* at Band 3 from the 2017 GMVA campaign. We searched in intensity and classified the pulses based on their circular and linear polarisation properties and arrival phase. We detected eight pulses with energies in the range of 10$^{29}$ erg. We constructed its cumulative energy distribution and we fit a power law, where the event rate scales with energy as $R \propto E^{\gamma}$. The result is an exponent of $\gamma = -2.4 \pm 0.1$. With the $\gamma -$value and the system properties of phased ALMA, we estimate that over 160 known pulsars could be detected by ALMA. For repeating FRBs, observing during their peak activity window could lead to several detections. We expect that ALMA's lower frequency bands with polarisation capabilities, will serve as a pioneer on mm wave searches for pulsars and to study complex environments involving radio transients.

Photodissociation Regions (PDRs) are key to understanding the feedback processes that shape interstellar matter in galaxies. One important type of PDR is the interface between HII regions and molecular clouds, where far-ultraviolet (FUV) radiation from massive stars heats gas and dissociates molecules. Photochemical models predict that the C/CO transition occurs deeper in the PDR compared to the H/H2 transition in low-metallicity environments, increasing the extent of CO-dark H2 gas. This prediction has been difficult to test outside the Milky Way due to the lack of high spatial resolution observations tracing H2 and CO. This study examines a low-metallicity PDR in the N13 region of the Small Magellanic Cloud (SMC) where we spatially resolve the ionization front, the H2 dissociation front, and the C/CO transition using 12CO J=2-1, 3-2 and [CI] (1-0) observations from the Atacama Large Millimeter/sub-mm Array (ALMA) and near-infrared spectroscopy of H2 vibrational lines from the James Webb Space Telescope (JWST). Our analysis shows that the separation between the H/H2 and C/CO boundaries is approximately 0.043 +- 0.013(stat.) +- 0.0036(syst.) pc (equivalent to 0."146 +- 0."042 (stat.) +- 0."012 (syst.) at the SMC's distance of 62 kpc), defining the spatial extent of the CO-dark H2 region. Compared to our plane-parallel PDR models, we find that a constant pressure model matches the observed structure better than a constant density one. Overall, we find that the PDR model does well at predicting the extent of the CO-dark H2 layer in N13. This study represents the first resolved benchmark for low metallicity PDRs.

One hypothesis for runaway stars (RSs) is that they are ejected from star clusters with high velocities relative to the cluster center-of-mass motion. There are two competing mechanisms for their production: supernova-based ejections in binaries, where one companion explodes, leaves no remnant, and launches the other companion at the instantaneous orbital velocity, and the disintegration of triples (or higher-order multiples), which produces a recoiled runaway binary (RB) and an RS. We search for RS candidates using data from the Gaia DR3 survey with a focus on triple disintegration since in this case the product is always a binary and a single star that should be moving in opposite directions. We created a systematic methodology to look for candidate RS-RB runaway pairs produced from the disintegration of bound three-body systems formed from single-binary interactions based on momentum conservation and causality. The method we use is general and can be applied to any cluster with a 5D kinematic data set. We used our criteria to search for these pairs in a 150 pc circular field of view surrounding the open cluster M67, which we used as a benchmark cluster to test the robustness of our method. Our results reveal only one RS-RB pair that is consistent with all of our selection criteria out of an initial sample of $10^8$ pairs.

Forthcoming measurements of the line-intensity-mapping power spectrum (PS) are expected to set precious constraints on several quantities of astrophysical and cosmological interest. Our study targets the [CII] luminosity function (LF) at high redshift, which is still highly uncertain, in particular at the faint end. As an example of future opportunities, we present forecasts for the Deep Spectroscopic Survey (DSS) that will be conducted with the Fred Young Submillimeter Telescope at $z \simeq 3.6$ and also make predictions for eventual $10\times$ wider and/or $\sqrt{10}\times$ more sensitive surveys. The halo-occupation properties of [CII] emitters in the MARIGOLD simulations provide us with the motivation to abundance match two versions of the ALPINE LF against the halo mass function. We employ the resulting luminosity-mass relation within the halo model to predict the expected PS signal and its uncertainty. Finally, we use Bayesian inference to analyse mock PS data and forecast what constraints could be achieved on the first two moments of the LF and on Schechter fits. Depending on the actual LF, the DSS will measure the clustering and shot-noise amplitudes of the PS with a signal-to-noise ratio of $\sim 3$ or higher. However, degeneracies with the bias parameter and redshift-space distortions make it unfeasible to extract the first moment of the LF. Even the widest and most sensitive survey we consider can only constrain it with a $50\%$ uncertainty. By jointly fitting the PS and the LF, we directly constrain Schechter-function parameters. We find that the normalisation and the cutoff luminosity are precisely and accurately measured while the faint-end slope remains highly uncertain (unless the true value approaches $-2$). Overall, increasing the survey sensitivity at fixed sky coverage yields greater improvements than covering a larger area at fixed sensitivity.

The correlations between successive measurements of a quantum system can violate a family of Leggett-Garg Inequalities (LGIs) that are analogous to the violation of Bell's inequalities of measurements performed on spatially separated quantum systems. These LGIs follow from a macrorealistic point of view, imposing that a classical system is at all times in a definite state and that a measurement can, at least in principle, leave this state undisturbed. Violations of LGIs can be probed by neutrino flavour oscillations if the correlators of consecutive flavour measurements are approximately stationary. We discuss here several improvements of the methodology used in previous analyses based on accelerator and reactor neutrino data. We argue that the strong claims of LGI violations made in previous studies are based on an unsuitable modelling of macrorealistic systems in statistical hypothesis tests. We illustrate our improved methodology via the example of the MINOS muon-neutrino survival data, where we find revised statistical evidence for violations of LGIs at the $(2-3)\sigma$ level, depending on macrorealistic background models.

In the audible axion mechanism, axion-like particles source primordial gravitational waves via their coupling to a dark Abelian gauge field. The original setup, however, relies on a large axion decay constant and coupling to produce sizable signals. In this article, we show that delaying the onset of axion oscillations opens up the testable parameter space and reduces the required coupling to $\alpha \gtrsim 1$. Furthermore, we investigate the emission of gravitational waves via the axion coupling to the Standard Model photon in the presence of Schwinger pair production, generating a strong signal in the $\mu$Hz or ultra-high frequency range. Cosmological constraints and gravitational wave projections are provided for both scenarios.

Can a stationary stone radiate gravitational waves (GWs)? While the answer is typically "no" in flat spacetime, we get a "yes" in inflationary spacetime. In this work, we study the stationary-stone-produced GWs in inflation with a concrete model, where the role of stones is played by massive higher-spin particles. We study particles of spin-2 and higher produced by helical chemical potentials, and show that the induced GWs feature a scale-invariant and helicity-biased power spectrum in the slow-roll limit. Including slow-roll corrections leads to interesting backreactions from the higher-spin boson production, resulting in an intriguing scale-dependence of GWs at small scales. Given the existing observational and theoretical constraints, we identify viable parameter regions capable of generating visibly large GWs for future observations.

Predicting the measurable statistical properties of density fluctuations in a supersonic compressible turbulent flow is a major challenge in physics. In 1951, Chandrasekhar derived an invariant under the assumption of the statistical homogeneity and isotropy of the turbulent density field and stationarity of the background density. Recently, Jaupart & Chabrier (2021) extended this invariant to non-isotropic flows in a time-evolving background and showed that it has the dimension of a mass. This invariant $M_{\rm inv}$ is defined by $M_{\rm inv} = \mathbb{E}(\rho)\text{Var}\left(\frac{\rho}{\mathbb{E}(\rho)}\right)(l_{\rm c}^\rho)^3$ where $\rho$ is the density field and $l_{\rm c}^\rho$ is the correlation length. In this article, we perform numerical simulations of homogeneous and isotropic compressible turbulence to test the validity of this invariant in a medium subject to isotropic decaying turbulence. We study several input configurations, namely different Mach numbers, injection lengths of turbulence and equations of state. We confirm that $M_{\rm inv}$ remains constant during the decaying phase of turbulence. Furthermore, we develop a theoretical model of the density field statistics which predicts without any free parameter the evolution of the correlation length with the variance of the logdensity field beyond the assumption of the gaussian field for the logdensity. Noting that $M_{\rm inv}$ is independent of the Mach number, we show that this invariant can be used to relate the non-gaussian evolution of the logdensity probability distribution function to its variance with no free parameters.

Rotation plays an important role in the evolution of most types of stars, in particular, it can have a strong influence on the evolution of a newly born proto-neutron star. In this study, we investigate the effects of rotation on four snapshots of the evolution of proto-neutron stars with hyperons and $\Delta$-resonances in their cores, from birth as neutrino-rich objects to maturity as cold, catalyzed neutron stars. We focus on the effects of uniform rotation on the macroscopic structure of the star at three rotational frequencies -- 346.53 Hz, 716 Hz, and the Kepler frequency. Our investigation indicates that the impact of rotation at frequencies of $346.53$~Hz and $716$~Hz causes minor changes in the maximum gravitational mass but leads to significant changes in the stellar radius, particularly for stars with masses smaller than $2$~\msun. However, we observe drastic changes in the star's mass and radius when considering the Kepler frequency. In addition, we investigate other relevant characteristics of the rotating proto-neutron stars as they evolve such as the moment of inertia, compactness, central temperature, and Kerr parameter. Our results suggest that the inclusion of new degrees of freedom in the stellar core lead the star to be more sensitive to rotational dynamics, owing to an increase in compactness, a decrease in the central temperature, and a decrease in the moment of inertia.

We present a Fisher information matrix study of the parameter estimation precision achievable by a class of future space-based, "mid-band", gravitational wave (GW) interferometers observing monochromatic signals. The mid-band is the frequency region between that accessible by LISA and ground-based interferometers. We analyze monochromatic signals from TianQin, gLISA, and gLISA$_d$, a descoped gLISA which has acceleration noise three orders of magnitude worse than gLISA. We find that all three missions achieve their best angular source reconstruction precision in the higher part of their accessible frequency band, with an error box better than $10^{-10}$ sr in the frequency band [$10^{-1},10$] Hz when observing a monochromatic GW signal of amplitude $h_0=10^{-21}$ that is incoming from a given direction. In terms of their reconstructed frequencies and amplitudes, TianQin achieves its best precision values in both quantities in the frequency band [$10^{-2}, 4\times 10^{-1}$] Hz, with a frequency precision $\sigma_{f_{gw}}=2\times 10^{-11}$ Hz and an amplitude precision $\sigma_{h_0}=2\times 10^{-24}$. gLISA matches these precisions in a frequency band slightly higher than that of TianQin, [$3\times 10^{-2},1$] Hz, as a consequence of its smaller arm length. gLISA$_d$, on the other hand, matches the performance of gLISA only over the narrower frequency region, [$7\times 10^{-1},1$] Hz, as a consequence of its higher acceleration noise at lower frequencies. The angular, frequency, and amplitude precisions as functions of the source sky location are derived assuming an average SNR of 10 at selected GW frequencies within TianQin and gLISA's bands. The same is done for gLISA$_d$ using amplitudes yielding an SNR of 10 for gLISA. We find that, for any given source location, all three missions display a marked precision improvement in the three reconstructed parameters at higher GW frequencies.

Based on the recent result that the action of matter fields is conformal form-invariant in its standard form and on the active and passive approaches to conformal transformations, we review the conformal form-invariant parametrization of scalar-tensor gravity theories. We investigate whether this parametrization is actually different from other existing parametrizations. We also check the accuracy of the claim that the classical physical predictions of these theories are conformal-frame invariants.

We investigate the effect of rainbow gravity on Klein-Gordon (KG) bosons in a quantized nonuniform magnetic field in the background of Bonnor-Melvin (BM) spacetime with a cosmological constant. In the process, we show that the BM spacetime introduces domain walls (i.e., infinitely impenetrable hard walls) at \(r = 0\) and \(r = \pi/\sqrt{2\Lambda}\), as a consequence of the effective gravitational potential field generated by such a magnetized BM spacetime. As a result, the motion of KG particles/antiparticles is restricted indefinitely within the range \(r \in [0, \pi/\sqrt{2\Lambda}]\), and the particles and antiparticles cannot be found elsewhere. Next, we provide a conditionally exact solution in the form of the general Heun function \(H_G(a, q, \alpha, \beta, \gamma, \delta, z)\). Within the BM domain walls and under the condition of exact solvability, we study the effects of rainbow gravity on KG bosonic fields in a quantized nonuniform external magnetic field in the BM spacetime background. We use three pairs of rainbow functions: \( f(u) = (1 - \tilde{\beta} |E|)^{-1}, \, h(u) = 1 \); and \( f(u) = 1, \, h(u) = \sqrt{1 - \tilde{\beta} |E|^\upsilon} \), with \(\upsilon = 1,2\), where \(u = |E| / E_p\), \(\tilde{\beta} = \beta / E_p\), and \(\beta\) is the rainbow parameter. We find that such pairs of rainbow functions, \((f(u), h(u))\), fully comply with the theory of rainbow gravity, ensuring that \(E_p\) is the maximum possible energy for particles and antiparticles alike. Moreover, we show that the corresponding bosonic states form magnetized, rotating vortices, as intriguing consequences of such a magnetized BM spacetime background.

We propose a novel mechanism to generate primordial magnetic fields (PMFs) strong enough to explain the observed cosmic magnetic fields. We employ a scalar field charged under U(1) gauge symmetry with a non-trivial VEV to provide an effective mass term to the EM field and thus break its conformal invariance. The primordial magneto-genesis takes place in the radiation dominated (RD) epoch, after the electroweak symmetry breaking (EWSB) phase. As a result, our mechanism is naturally free from the over-production of electric fields due to high conductivity in the RD epoch, and the baryon isocurvature problem which takes place only if magneto-genesis happens before the ESWB phase. In addition, we find that a significant amount of PMFs can be generated when the scalar field experiences a tachyonic phase. In this case, the scalar field is light and weakly coupled and has negligible energy density compared to the cold dark matter, hence the strong coupling problem and the back-reaction problem are also absent. Therefore, our model is free from the above-mentioned problems that frequently appear in other primordial magneto-genesis scenarios.

Detecting unusual signals in observational solar spectra is crucial for understanding the features associated with impactful solar events, such as solar flares. However, existing spectral analysis techniques face challenges, particularly when relying on pre-defined, physics-based calculations to process large volumes of noisy and complex observational data. To address these limitations, we applied deep learning to detect anomalies in the Stokes V spectra from the Hinode/SP instrument. Specifically, we developed an autoencoder model for spectral compression, which serves as an anomaly detection method. Our model effectively identifies anomalous spectra within spectro-polarimetric maps captured prior to the onset of the X1.3 flare on May 5, 2024, in NOAA AR 13663. These atypical spectral points exhibit highly complex profiles and spatially align with polarity inversion lines in magnetogram images, indicating their potential as sites of magnetic energy storage and possible triggers for flares. Notably, the detected anomalies are highly localized, making them particularly challenging to identify in magnetogram images using current manual methods.

In the hunt for WIMPish dark matter and testing our new theory, we extend the results obtained for the Kepler problem in NQG I and NQG II to the Euler two-centre problem and to other classical Hamiltonian systems with planar periodic orbits. In the first case our results lead to quantum elliptical spirals converging to elliptical orbits where stars and other celestial bodies can form as the corresponding WIMP/molecular clouds condense. The examples inevitably involve elliptic integrals as was the case in our earlier work on equatorial orbits of toy neutron stars (see Ref. [27]). Hence this is the example on which we focus in this work on quantisation. The main part of our analysis which leans heavily on Hamilton-Jacobi theory is applicable to any KLMN integrable planar periodic orbits for Hamiltonian systems. The most useful results on Weierstrass elliptic functions needed in these two works we have summarised with complete proofs in the appendix. This has been one of the most enjoyable parts of this research understanding in more detail the genius of Weierstrass and Jacobi. However we have to say that the beautiful simplicity of the Euler two-centre results herein transcend even this as far as we are concerned. At the end of the paper we see how the Burgers-Zeldovich fluid model relates to our set-up through Nelson's stochastic mechanics.

String field theory motivated infinite-derivative models lead to non-local gravity modifications which form a promising class of quantum gravity candidates. In this paper we investigate effects of non-locality on the three-point function (the bi-spectrum) during cosmic inflation. The study is done in an Einstein frame with an infinite-derivative scalar field Lagrangian minimally coupled to the Einstein-Hilbert term. A non-local generalization of the Mukhanov-Sasaki equation is derived. Infinite-derivative operators present in this equation lead to an appearance of infinitely many new background induced states in the perturbation spectrum during inflation with complex masses on top of a usual nearly massless inflaton. On contrary to a flat background such states can be classically stable in a de Sitter space-time. This helps preserving observational constraints on the scalar power-spectrum. We proceed by studying a particular configuration assuming that the generalized Mukhanov-Sasaki equation gives rise to an inflaton and one pair of new states with complex conjugate masses as perturbative degrees of freedom. The corresponding scalar bi-spectrum is computed numerically in squeezed and equilateral limits. We use the latest observational constraints on amplitude of the bi-spectrum $f_{NL}$ from Planck 2018 dataset as a guideline for possible values of masses of new emerging states. We find that $f_{NL}$ is non-trivially sensitive to the values of complex masses and this can reduce the parameter space of gravity modifications. In particular we find that the amplitude of the squeezed limit gets easily enhanced while of the equilateral limit can stay like in a local single-field model of inflation. We end up discussing open questions relevant for this class of models of inflation.

Black hole quasinormal mode frequencies can be very close to each other ("avoided crossings") or even completely degenerate ("exceptional points") when the system is characterized by more than one parameter. We investigate this resonant behavior and demonstrate that near exceptional points, the two modes are just different covers of the same complex function on a Riemann surface. We also study the characteristic time domain signal due to the resonance in the frequency domain, illustrating the analogy between black hole signals at resonance and harmonic oscillators driven by a resonant external force. We carry out a numerical study of resonances between the fundamental mode and the first overtone in a specific toy model. We find that quasinormal mode frequencies will not be accurately constrained unless we take into account the effect of resonances.

At the extreme densities in neutron stars, a phase transition to deconfined quark matter is anticipated. Yet masses, radii and tidal deformabilities offer only indirect measures of a first-order phase transition, requiring many detections to resolve or being ineffective observables if the discontinuity exists at lower densities. We report on a smoking-gun gravitational-wave signature of a first-order transition: the resonant tidal excitation of an interface mode. Using relativistic perturbation theory with an equation-of-state family informed by chiral effective field theory, we show that such a resonance may be detectable with next-generation interferometers and possibly already with LIGO A+ for sufficiently loud events.

Schwarzschild black holes evolve toward their static configuration by emitting gravitational waves, which decay over time following a power law at fixed spatial positions. We derive this power law analytically for the second-order even gravitational perturbations, demonstrating that it is determined by the fact that the second-order source decays as the inverse square of the distance. Quadratic gravitational modes with multipole $\ell$ decay according to a law $\sim t^{-2\ell-1}$, in contrast to the linear Price law scaling $\sim t^{-2\ell-3}$. Consequently, nonlinear tails may persist longer than their linear counterparts.