Papers for Wednesday, Aug 06 2025

Satellite images present unique challenges due to their high object variability and lower spatial resolution, particularly for detecting atmospheric gravity waves which exhibit significant variability in scale, shape, and pattern extent, making accurate localization highly challenging. This variability is further compounded by dominant unwanted objects such as clouds and city lights, as well as instrumental noise, all within a single image channel, while conventional detection methods struggle to capture the diverse and often subtle features of gravity waves across varying conditions. To address these issues, we introduce YOLO-DCAT incorporating Multi Dilated Residual Convolution (MDRC) and Simplified Spatial and Channel Attention (SSCA), an enhanced version of YOLOv5 specifically designed to improve gravity wave localization by effectively handling their complex and variable characteristics. MDRC captures multi-scale features through parallel dilated convolutions with varying dilation rates, while SSCA focuses on the most relevant spatial regions and channel features to enhance detection accuracy and suppress interference from background noise. In our experiments, the improved model outperformed state-of-the-art alternatives, improving mean Average Precision (mAP) by over 14% and Intersection over Union (IoU) by approximately 17%, demonstrating significantly improved localization accuracy for gravity waves in challenging satellite imagery and contributing to more precise climate research and modeling.

We present the design, fabrication, and testing of R-FLEX, a novel flexure mechanism for next-generation fiber-fed astronomical instruments. As the current Dark Energy Spectroscopic Instrument (DESI) revolutionizes cosmology with over 56 million collected spectra using 5,000 robotic fiber positioners at 10.4 mm pitch, we project that future instruments will require 2.5-3x smaller fiber robots by area. R-FLEX enables precision radial motion for fiber robots mountable at 6.2 mm pitch, delivering repeatable positioning accuracy $\leq$ 5 $\mu$m over a 4 mm travel range. The travel range extends outside the robot's mechanical envelope, providing complete patrol coverage of the focal surface. The R-FLEX design must meet challenging requirements for parasitic motion < 30 $\mu$m, angular misalignment < 0.3°, 1 million cycle lifetime, operating in a mountaintop telescope environment, and is suitable for mass production of $\sim$30,000 units.

This white paper was submitted to NASA's Search For Life Science Analysis Group (SFL-SAG): To ensure that the first mission designed to seek signs of extant life since 1976 is able to produce an unambiguous biological interpretation, the SFL-SAG is tasked with identifying the most high-confidence, agnostic biosignatures which are targetable, detectable, and measurable in Martian subsurface mid-latitude ice. To aid in this effort, this white paper highlights three examples of target materials or phenomena, along with associated instrument concepts, which the SFL-SAG shall prioritize in its efforts to define the appropriate astrobiological strategy. These include 1) polyelectrolyte informational biopolymers, 2) macromolecular biological homochirality, and 3) chiral-specific metabolic reactions. The Agnostic Life Finding Association (ALFA) and University of Florida (UF) support the development of instrumentation that seeks these high-confidence biosignatures.

The prevalence and properties of low-mass dark matter haloes serve as a crucial test for understanding the nature of dark matter, and may be constrained through the gravitational deflection of strongly lensed arcs. Previous studies found evidence for the presence of low-mass dark matter haloes in observations of the gravitationally lensed, dusty star-forming galaxy SDP.81, using the Atacama Large Millimetre/sub-millimetre Array (ALMA). In this work, we analyse these observations to assess the robustness of these reported results. While our analysis indicates that the data support additional angular structure in the lensing mass distribution beyond an elliptical power-law density profile, we do not find evidence for two previously reported sub-halo detections. However, we verify with realistic mock data that we could have found evidence in favour of a previously reported $\approx 10^{9}\,{\rm M_{\odot}}$ sub-halo with a log Bayes factor of 29, should it exist in the real data. After testing various systematics, we find that this previous sub-halo inference was most likely spurious and resulted from an inadequate smooth model, specifically, poorly fitting multipoles. While we do not find evidence in favour of any individual sub-halo, we find evidence for similarity in the lensing signatures of multipoles ($m=3,4$) and single massive sub-haloes, consistent with other recent work. We suggest that future searches for low-mass haloes in lensed arcs include lens angular structure in the form of multipoles up to 4th order and require a good-fitting smooth model as a prerequisite. Overall, our findings demonstrate the suitability of ALMA data of this quality to simultaneously constrain the abundance of low-mass haloes and lens angular structure.

Interstellar objects (ISOs) provide unique insights into the building blocks and conditions of extrasolar planetary systems. The newly discovered object, 3I/ATLAS (C/2025 N1), represents the third known ISO after 1I/'Oumuamua and 2I/Borisov. We present initial spectroscopic characterizations of 3I using observations from the Goodman High Throughput Spectrograph on the 4.1 m SOAR Telescope in Chile during the night of July 3rd. The reflectance spectrum of 3I, covering 3700-7000\,Å\, reveals a red continuum, comparable to extreme trans-Neptunian objects, with a weak UV-optical turnover indicative of complex carbonaceous and irradiated organics. At the time of observation, when 3I was at a heliocentric distance of 4.4 AU, we detected no discernible gas emission from canonical cometary species (CN, C$_3$, C$_2$, CO$^+$, [O{\sc i}]). This is in agreement with expectations from our thermal-evolution model, which indicates sublimation-driven activity should commence once 3I/ATLAS approaches smaller heliocentric distances. Nonetheless, the paradoxical situation of early onset coma without evidence of sublimation tracers calls for other dust-liberating mechanisms that ancient ISOs may be subjected to at large heliocentric distances.

The Euclid survey aims to trace the evolution of cosmic structures up to redshift $z$ $\sim$ 3 and beyond. Its success depends critically on obtaining highly accurate mean redshifts for ensembles of galaxies $n(z)$ in all tomographic bins, essential for deriving robust cosmological constraints. However, photometric redshifts (photo-$z$s) suffer from systematic biases arising from various sources of uncertainty. To address these challenges, we utilised self-organising maps (SOMs) with mock samples resembling the Euclid Wide Survey (EWS), to validate Euclid's uncertainty requirement of $|\Delta\langle z \rangle| = \langle z_{\text{est}} \rangle - \langle z \rangle \leq 0.002 (1+z)$ per tomographic bin, assuming DR3-level data. We observe that defining the redshift tomography using the mean spectroscopic redshift (spec-$z$) per SOM cell, results in none of the ten tomographic redshift bins satisfying the requirement. In contrast, the redshift tomography on the photo-$z$s of the EWS-like sample yields superior results, with eight out of ten bins [$0 < z\leq 2.5$] meeting the Euclid requirement. To enhance the realism of our study, we morph our calibration sample to mimic the C3R2 survey in incremental steps. In this context, a maximum of six out of ten bins meet the requirement, strongly advocating the adoption of a redshift tomography defined by the photo-$z$s of individual galaxies rather than the commonly used mean spec-$z$ of SOM cells. To examine the impact on the expected biases for $\Omega_{\text{m}}$, $\sigma_{8}$, and $\Delta w_{0}$ measured by Euclid, we perform a Fisher forecast for cosmic shear only, based on our redshift uncertainties. Here, we find that even under an evaluation of the uncertainty where the impact of the redshift bias is substantial, most absolute biases remain below 0.1$\sigma$ in the idealised scenario and below 0.3$\sigma$ in the more realistic case.

Near-infrared imaging is a powerful technique in observational astronomy, but the bright background, primarily from the Earthś atmosphere, makes the detection of faint features particularly challenging. To recover low surface brightness (LSB) structures in such data, we present NASIM (Near-infrared Automated low Surface brightness reduction In Maneage), a fully automated and reproducible data reduction pipeline optimised for VISTA/VIRCAM observations. NASIM builds on GNU Astronomy Utilities (Gnuastro) to effectively remove large-scale instrumental artefacts while preserving faint, diffuse emission. As a key science application, we focus on deep Ks-band observations of the Euclid Deep Field South (KEDFS), one of the deepest VISTA/VIRCAM datasets and a high-priority field for synergy with current and future facilities, including Euclid, JWST, LSST, Roman, Spitzer, and ALMA. With VIRCAM no longer operational, KEDFS now stands as a unique legacy dataset. We release selected tiles from the KEDFS survey and highlight science cases, including galaxy outskirts, LSB galaxies, and intracluster light, that demonstrate NASIMś ability to recover diffuse structures. A direct comparison with conventional VISTA data reduction pipelines demonstrates the advantages of NASIM in preserving diffuse emission without compromising compact source detection. All quantitative results presented in this paper are fully reproducible with Maneage (commit 4d32667).

We present an upgraded version of TRICERATOPS, a software package designed to calculate false positive probabilities for planet candidates identified by the Transiting Exoplanet Survey Satellite (TESS). This enhanced framework now incorporates ground-based light curves in separate bandpasses, which are routinely obtained as part of the candidate vetting process. We apply this upgraded framework to explore the planetary nature of 14 TESS planet candidates, combining primarily J band light curves acquired with the 200-inch Hale Telescope at Palomar Observatory with complementary archival observations from the Las Cumbres Observatory Global Telescope (LCOGT), the Fred Lawrence Whipple Observatory (FLWO), and the Teide Observatory, along with existing TESS data and contrast curves from high-resolution imaging. As a result of this analysis we statistically validate (False Positive Probability < 1.5% and Nearby False Positive Probability < 0.1%) six new planets in five systems: TOI-1346 b, TOI-1346 c, TOI-2719 b, TOI-4155 b, TOI-6000 b, and TOI-6324 b. For these systems, we provide updated estimates of their stellar and planetary properties derived from the TESS and ground-based observations. These new systems contain planets with radii between 0.9-6 Re and orbital periods between 0.3-5.5 days. Finally, we use our upgraded version of TRICERATOPS to quantify the relative importance of multi-wavelength transit photometry and high-resolution imaging for exoplanet candidate validation, and discuss which kinds of candidates typically benefit the most from ground-based multi-color transit observations.

Blue horizontal-branch (BHB) stars are old, low-mass, metal-poor stars that serve as important tracers of the Galactic halo structure, kinematics, and this http URL their binary properties provides key insights into their formation channels and the role of binary interactions in the evolution of horizontal branch stars. We intend to investigate the intrinsic binary fraction $f_{\rm b}^{\rm in}$ of BHB stars and its dependencies on metallicity, kinematics, and effective temperature. We collect \GG{299} BHB stars from LAMOST with multiple radial velocity (RV) measurements and classify the sample into halo-like and disk-like BHBs based on their kinematics and metallicity, as well as into bluer and redder BHBs based on their \G{effective temperature}. We then investigate the observed binary fraction for each group based on the radial velocity variations and apply a set of Monte Carlo simulations, assuming distributions of $f(P) \propto P^\pi$ and $f(q) \propto q^\kappa$, to correct the observed binary fraction for observational biases and derive the intrinsic binary fraction. After correcting for observational biases, the intrinsic binary fraction increases to 31% for n > 2 and 32% for n > 3. A clear contrast is observed between halo-like and disk-like BHB stars, with halo-like BHBs exhibiting a lower intrinsic binary fraction (28% for n > 2 and 29% for n> 3) compared to disk-like BHBs (46% and 51%, respectively), indicating different formation pathways. Additionally, we find that bluer BHB stars exhibit a significantly higher binary fraction (42% for n > 2 and 45% for n> 3) than redder BHB stars (24% and 23%, respectively), which suggests a possible link between binarity and the effective temperature, although more samples are required to confirm this.

We present a multiwavelength spectroscopic survey of 23 luminous mid-infrared-selected Type-2 quasars at redshifts z = 0.88 to 3.49. The targets were selected in the SDSS Stripe 82 field based on their bright WISE W4 detections (flux > 5 mJy) and extremely faint or red optical counterparts (e.g., r > 23 or r - W4 > 8.4), designed to identify heavily obscured quasars. Deep near-infrared (Gemini/GNIRS) and optical (Keck/LRIS and KCWI) spectroscopy confirm 23 out of 24 candidates as Type-2 quasars in this redshift range, including 12 objects at z > 2. The spectra exhibit strong rest-frame UV and optical emission lines (Ly-alpha, C IV, [O III], H-alpha) with a wide range of line widths, indicating significant spectral diversity. Approximately one-third of the sample (8 of 23) shows broad H-alpha emission (FWHM > 2000 km/s) despite their Type-2 classification, while the rest have only narrow lines (FWHM < 2000 km/s) characteristic of classical obscured quasars. Notably, these broad-line Type-2 quasars share similar spectral energy distributions with the JWST-discovered "little red dot" (LRD) AGNs, suggesting that our sample could be lower-redshift analogues of the heavily obscured broad-line AGNs uncovered by JWST. We also find that the [O III] 5007 angstrom emission is relatively weak for their high bolometric luminosities, deviating from trends seen in lower-redshift Type-2 QSOs. A new composite spectrum for Type-2 QSOs is built using our sample. Overall, our results demonstrate that mid-IR selection efficiently uncovers a diverse population of obscured quasars and that spectroscopic follow-up is crucial for revealing their true nature. This study provides new insights into heavily obscured SMBH growth at cosmic noon and bridges the gap to the obscured AGN populations now being revealed by JWST.

Recent measurements of astrophysical neutrinos have expanded our understanding of their nature and origin. However, very little is still known about the astrophysical $\bar{\nu}:\nu$ ratio. The only prior measurement is the recent, single Glashow event seen by IceCube. Understanding the astrophysical $\bar{\nu}:\nu$ ratio has a bearing on multiple questions, including the astrophysical spectral shape and neutrino production mechanisms. This analysis uses a new approach to measuring the astrophysical muon $\bar{\nu}:\nu$ ratio at various energies. It uses inelasticity, the fraction of the initial neutrino energy carried away by the hadronic shower. Inelasticity probes the $\bar{\nu}:\nu$ ratio due to the fact that at energies below roughly 100 TeV, valence quarks dominate in deep inelastic scattering interactions, leading to different neutrino and antineutrino inelasticities and cross-sections. We use 10.3 years of IceCube data consisting of starting tracks at energies between 1 TeV and 1 PeV with a self-veto selection that enhances astrophysical event purity in the down-going direction. Based on this sample and analysis method, we present the first measurement of the astrophysical $\bar{\nu}:\nu$ ratio at sub-PeV energies.

The proper motion (also known as position drift) field of extragalactic sources at cosmological distances across our sky can be used to measure the acceleration of the Solar System through the aberration effect. If measured very precisely, the signal would also hold cosmological information, for instance about bulk flows of distant sources or the presence of tensor modes. In the $\Lambda$ cold dark matter ($\Lambda$CDM) model, the acceleration of the Solar System is by far the dominant contributor to the position drift signal for sources at cosmological distances, and the measurement is therefore expected to yield a constant spheroidal dipole across redshifts as long as convergence to the cosmic restframe has been reached. The aim of this paper is to test this hypothesis. We analyze data from the cosmic reference frame dataset of Gaia data release 3 focusing on constraining the dipole and quadrupole in the position drift signal, with an emphasis on redshift dependence of the signal as a consistency test of the $\Lambda$CDM model. The spheroidal dipole that we find is in mild tension, at the level of $2-3\sigma$, with the constant-in-redshift signature expected from the local acceleration of the Solar System. We also find significant quadrupole components, that however do not have any significant evolution with redshift. The most straightforward interpretation of these findings is (unknown) systematic errors related to the Gaia instrumentation, but a cosmological origin is a possibility. Our analysis remains inconclusive on the cause of the redshift dependence of the dipole and warrants further investigations with upcoming data releases. We discuss possible implications of our results and highlight the importance of proper motion measurements for rest frame determinations in cosmology. In our discussion, we highlight interesting avenues for doing cosmology with Gaia data.

The diffuse starlight extending throughout massive galaxy clusters, known as intracluster light (ICL), has the potential to be read as a memoir of mass accretion: informative, individual, and yet imperfect. Here, we combine dark matter-only zoom-in simulations from the Symphony suite with the Nimbus "star-tagging" model of the stellar halo to assess how much information about the mass assembly of an individual galaxy cluster can be gleaned from idealized measurements of ICL outskirts. We show that the edges of a cluster's stellar profile -- the primary (Rsp*1) and secondary (Rsp*2) stellar "splashback" radii -- are sensitive to both continuous mass accretion histories and discrete merger events, making them potentially powerful probes of a cluster's past. We find that Rsp*1 strongly correlates with the cluster's mass ~1 dynamical time ago, while Rsp*2 traces more recent mass accretion history to a slightly lesser degree. In combination, these features can further distinguish between clusters that have and have not undergone a major merger within the past dynamical time. We use both to predict realistic cluster mass accretion histories with the MultiCAM framework. These outer ICL features are significantly more sensitive to mass accretion and merger histories than the stellar mass gap and halo concentration, and perform comparably to the commonly used X-ray-based tracer of relaxedness, x_off. While our analysis is idealized, the relevant ICL features are potentially detectable in next-generation deep imaging of nearby clusters. This work highlights the promise of ICL measurements and lays the groundwork for more detailed forecasts of their power.

Water masers are common in star-forming regions (SFRs), with the 22.235 GHz transition widely detected in both high- and low-mass protostars. In contrast, (sub)millimeter water maser transitions remain poorly studied, especially in low-mass SFRs. We search for millimeter water masers in a sample of low-mass SFRs previously known to exhibit 22 GHz emission. We target the transitions at 183.3, 321.2, and 325.2 GHz, respectively. We also examine their potential as probes of evolutionary stage by comparing them with previously reported Class I methanol masers (MM). We used the APEX 12m telescope. To assess the evolutionary stage of each source, we modeled their spectral energy distributions (SEDs) using archival data and used the derived dust temperatures as proxies of ages. We then compared the occurrence of water and methanol masers across the sample. We detected 183.3 GHz water masers in 5 out of 18 sources. IRAS 16293-2422 shows all three transitions, while Serpens FIRS 1 also displays the 321.2 GHz line. Despite excellent observing conditions, detection rates drop with increasing frequency, reflecting both intrinsic line weakness and variability. Notably, the brightest (sub)millimeter masers can reach flux densities comparable to the 22 GHz line. Comparisons of velocity profiles show that different transitions often trace distinct gas components. Water masers generally appear at earlier or comparable evolutionary stages than MM, suggesting no universal maser-based age sequence. Our results demonstrate the detectability of submillimeter water in low-mass SFRs, although their occurrence is sparse. Velocity overlap between some centimeter and millimeter components suggests partial spatial coincidence, but many features appear uniquely in one frequency regime, indicating that different transitions often trace distinct gas regions with varying physical conditions.

The MESSENGER mission revealed unexpectedly high sulfur content within Mercury's surface, deviating from the Lunar regolith, which was, until recently, considered a good Mercury analogue. Mercury's exposure to energetic space weathering processes such as meteoritic impact and solar-wind sputtering suggests this high sulfur concentration should be reflected in the suprathermal sulfur population of the Hermean exosphere. UV spectroscopy has not yet detected exospheric sulfur, a result attributed primarily to its low glow-factor. Future detection by BepiColombo's Mass Spectrum Analyzer depends on sulfur abundance in the exosphere. Radiation-induced segregation has been observed in the common sulfide troilite (FeS), a constituent mineral in returned Lunar samples, meteorites, and asteroids, where the resulting metal cap is expected to reduce sulfur ejection to Mercury's exosphere. In this work, we investigate the irradiation response of Mercury-relevant sulfides. Niningerite (MgS) and oldhamite (CaS) were irradiated with solar-wind speed 2 keV H$_2^+$ or 4 keV He$^+$, and in-situ compositional and chemical bond analysis as a function of fluence was performed using an XPS microprobe. Neither MgS nor CaS expressed detectable damage-induced segregation and instead reached metal-to-sulfur ratios close to bulk with irradiation. Based on this finding, structural information, and literature analyses, we infer that an S-S anionic spacing exceeding $\sim$3.2 Å inhibits radiation-induced sulfur depletion and promotes stoichiometric sputtering. We therefore predict no cation (metal) surface segregation in Hermean sulfides and no reduction in suprathermal sulfur emission caused by metal cladding formation in TiS, CrS, and Ca-Mg sulfides. This radiation-hardness for Mercury-relevant sulfides is novel and unexpected, and should facilitate detection in Mercury's exosphere by the BepiColombo mission.

We present an analysis of $\sim$235 ks of Chandra observations obtained over $\sim$19 years of the nearby dwarf starburst galaxy IC 10 in order to study the X-ray variability and X-ray luminosity function (XLF) of its X-ray binary (XRB) population. We identify 23 likely XRBs within the 2MASS $K_S$ isophotal radius and find the distributions of their dynamic ranges and duty cycles are consistent with a young, high-mass XRB population dominated by supergiant (sg)-fed systems, consistent with previous work. In general, we find that brighter HMXBs (those with $L_X\gtrsim$several$\times10^{36}$ erg s$^{-1}$) have higher duty cycles (i.e., are more persistent X-ray sources) than fainter objects, and the dynamic ranges of the sgHMXBs in the lower metallicity environment of IC 10 are higher than what is observed for comparable systems in the Milky Way. After filtering out foreground stars on the basis of Gaia parallaxes we construct, for the first time, the XLF of IC 10. We then use the XLF to model the star formation history of the galaxy, finding that a very recent (3-8 Myr) burst of star formation with rate of $\sim$0.5 $M_{\odot}$ yr$^{-1}$ is needed to adequately explain the observed bright-end ($L_X\sim10^{37}$ erg s$^{-1}$) of the HMXB XLF.

Observations of energy-dependent photon time delays from distant flaring sources provide significant constraints on Lorentz Invariance Violation (LIV). Such effects originate from modified vacuum dispersion relations, causing differences in propagation times for photons emitted simultaneously from gamma-ray bursts, active galactic nuclei, or pulsars. These modifications are often parametrized within a general framework by an effective quantum gravity energy scale $E_{QG,n}$. While such general constraints are well established in the LIV literature, their translation into specific coefficients of alternative theoretical frameworks, such as the Standard-Model Extension (SME), is rarely carried out. In particular, existing bounds on the quadratic case ($n=2$) of $E_{QG,n}$ can be systematically converted into constraints on the non-birefringent, CPT-conserving SME coefficients $c^{(6)}_{(I)jm}$. This work provides a concise overview of the relevant SME formalism and introduces a transparent conversion method from $E_{QG,2}$ to SME parameters. We review the most stringent time-of-flight-based bounds on $E_{QG,n}$ and standardize them by accounting for systematics, applying missing prefactors, and transforming results into two-sided Gaussian uncertainties where needed. We then use these standardized constraints, along with additional bounds from the literature, to improve bounds on the individual SME coefficients of the photon sector by about an order of magnitude. A consistent methodology is developed to perform this conversion from the general LIV framework to the SME formalism.

We present high angular resolution observations of the third known interstellar interloper, 3I/ATLAS, from the Hubble Space Telescope. The object is clearly active at 3.8 au pre-perihelion, showing dust emitted from the hot Sun-facing side of the nucleus and a weak, radiation pressure swept tail away from the Sun. We apply a simple model to estimate the mass loss rate in dust as dM/dt = 6 a kg/s, where a is the mean particle size in microns. With 1 < a < 100, we infer dM/dt = 6 to 60 kg/s. A fit to the surface brightness distribution of the inner coma limits the effective radius of the nucleus to be r < 2.8 km, assuming red geometric albedo 0.04. Conversely, the nucleus cannot be smaller than 0.16 km in radius if its coma is supplied by sublimation of carbon monoxide, and must be larger if a less volatile molecule drives the mass loss.

Faraday rotation measure synthesis is a well-known approach originated in Burn (1966) and later developed by Sokoloff et al. (1998) and Brentjens \& de Bruyn (2005) for studying magnetic fields. This work presents a complementary approach--the polarization frequency analysis (PFA)--allowing the properties of the turbulent magnetic field, which are difficult for Burn's original approach. Based on synthetic polarization observation of MHD turbulence simulation data, we study the influence of the coupling effect between density and magnetic field on synchrotron polarization dispersion. By applying the PFA to different simulated interstellar turbulence environments, we find that the PFA technique can reveal the scaling slope of the turbulent magnetic field in the case of a weak coupling effect and can also reflect the scaling slope of the rotation measure in the case of a strong coupling effect. Since avoiding the influence of Faraday depolarization, the PFA technique is a promising way to uncover turbulence properties using observational data from the Low-Frequency Array for Radio Astronomy and the Square Kilometer Array.

A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Lyman-alpha absorbers (DLAs) in the early universe. We conducted a survey aimed at discovering DLAs along sight lines to high-z quasars in order to measure element abundances at z>4. Here we report our first results from this survey for 10 DLAs with redshifts of ~4.2-5.0. We determine abundances of C, O, Si, S, and Fe, and thereby the metallicities and dust depletions. We find that DLA metallicities at z>4.5 show a wide diversity spanning ~3 orders of magnitude. The metallicities of DLAs at 3.7<z<5.3 show a larger dispersion compared to that at lower redshifts. Combining our sample with the literature, we find a relatively smooth evolution of metallicity with redshift out to z~5.3, with a tentative (~2 sigma) indication of a slight rise in metallicity at 4.5<z<5.3. The relative abundances exhibit C enhancement for both metal-poor and metal-enriched DLAs. In addition, alpha-element enhancement is evident in some DLAs, including a DLA at z=4.7 with a super-solar metallicity. Comparing [C/O] and [Si/O] with model predictions, 4 DLAs in our survey seem consistent with a non-zero Pop III contribution (3 with >=30% Pop-III contribution). Combining our sample and the literature, we find the dust depletion strength and dust-to-metal ratios to correlate positively with the total (gas+solid phase) metallicity, confirming the presence of metal-rich, dusty DLAs even at ~1 billion years after the Big Bang.

The formation and evolution of haze layers in planetary atmospheres play a critical role in shaping their chemical composition, radiative balance, and optical properties. In the outer solar system, the atmospheres of Titan and the giant planets exhibit a wide range of compositional and seasonal variability, creating environments favorable for the production of complex organic molecules under low-temperature conditions. Among them, Uranus -- the smallest of the ice giants -- has, since Voyager 2, emerged as a compelling target for future exploration due to unanswered questions regarding the composition and structure of its atmosphere, as well as its ring system and diverse icy moon population (which includes four possible ocean worlds). Titan, as the only moon to harbor a dense atmosphere, presents some of the most complex and unique organics found in the solar system. Central to the production of these organics are chemical processes driven by low-energy photons and electrons (<50 eV), which initiate reaction pathways leading to the formation of organic species and gas phase precursors to high-molecular-weight compounds, including aerosols. These aerosols, in turn, remain susceptible to further processing by low-energy UV radiation as they are transported from the upper atmosphere to the lower stratosphere and troposphere where condensation occurs. In this review, I aim to summarize the current understanding of low-energy (<50 eV) photon- and electron-induced chemistry, drawing on decades of insights from studies of Titan, with the objective of evaluating the relevance and extent of these processes on Uranus in anticipation of future observational and in situ exploration.

We analyzed the archival ALMA data of the nuclear region of M87 and evaluate the molecular gas content from the CO(2--1) absorption line. We found an enigmatic variability in the absorption line depth between two epochs separated by only two months. We reexamined the dataset used in the analysis and found that the bandpass calibration source within the same dataset also revealed a similar absorption line structure. Furthermore, we observed a rise in the system noise temperature spectrum. We concluded that the absorption line structure identified in a previous study, and attributed to CO(2--1), does not originate from M87 but instead results from telluric contamination, and that we still have only the upper limit on the molecular gas around the nucleus of M87.

Stellar age determination for large samples of stars opens new avenues for a broad range of astronomical sciences. While precise stellar ages for evolved stars have been derived from large ground- and space-based stellar surveys, reliable age determination for cool main-sequence dwarf stars remains a challenge. In this work, we set out to estimate the age of dwarf stars from the LAMOST spectra with a data-driven approach. We build a training set by using wide binaries that the primary component has reliable isochrone age estimate thus gives the age of the secondary. This training set is further supplemented with field stars and cluster stars whose ages are known. We then train a data-driven model for inferring age from their spectra with the XGBoost algorithm. Given a spectral signal-to-noise ratio greater than 50, the age estimation precise to 10% to 25% for K-type stars, as younger stars have larger relative errors. Validations suggest that the underlying information used for our age estimation is largely attributed to the LAMOST spectral features of chemical abundances. It means our result is a manifestation of stellar chemical clock effectively acted on LAMOST spectra ($R\simeq1800$). Applying our model to the LAMOST DR10 yields a massive age catalog for $\sim4$ million dwarf stars. Statistical properties, such as the age distribution, age-abundance and age-stellar activity relations of the sample stars are discussed. The catalog is publicly accessible and can be helpful for extensive sciences from detection and characterization of Earth-like planets to Galactic archaeology.

Intergalactic wandering stars (IWSs) within 10 Mpc remain a poorly explored area of astronomy. Such stars, if they exist, are supposed to be wandering objects as they are not bounded by the gravitational potential of any galaxy. We set out to conduct dedicated studies for unraveling such a wandering stellar population. As the first paper of the series, in the present work we model the distance distribution and luminosity function of IWSs formed via the Hills mechanism of the Galactic central massive black hole (GCMBH). We implement a numerical simulation to generate IWSs taking the ejection history of the GCMBH and the stellar evolution process into consideration, and present their luminosity function in the distance range of 200kpc - 10Mpc. Our results suggest that a few hundred thousand IWSs have been generated by the GCMBH via the Hills mechanism in the past 14 billion years. These IWSs have an apparent magnitude peaking at 30 to 35 mag in SDSS $r-$band, which are hard to detect. However, a few thousand of them at the bright end are detectable by upcoming wide-field deep surveys, such as China Space Station Telescope (CSST) and Vera Rubin Observatory (LSST). The forthcoming discovery of such a wandering stellar population will open a door for precise understanding of the matter constitution of the nearby intergalactic space and the dynamical history of galaxies in the local universe.

We modify the probabilistic formalism developed by Elvis (2014) to estimate the number of lunar craters that contain ore-bearing asteroid remnants. When we consider craters at or above a threshold diameter of 1 km, we estimate an upper limit of ${\sim}6,500$ craters with asteroid remnants containing significant amounts of platinum group metals and an upper limit of ${\sim}3,400$ craters with asteroid remnants that contain significant amounts of water in the form of hydrated minerals. For a more conservative threshold of 5 km, we estimate $\lesssim400$ craters with asteroid remnants that contain significant amounts of platinum group metals. These values are one to two orders of magnitude larger than the number of ore-bearing near-Earth asteroids estimated by Elvis (2014), implying that it may be more advantageous, and hence more profitable, to mine asteroids that have impacted the Moon rather than the ones that are in orbit.

Active Galactic Nucleus jets have long be thought to exhibit a conical jet shape, but recently, several jets were found to have a transition from parabolic to conical structure. As more sources are investigated, this collimation profile appears to represent a common paradigm. Previous works suggest that the Bondi radius may serve as an indicator of the transition location, although discrepancies have been observed in some sources. To explore this further, we selected CTA 102 for which existing literature presents mixed evidence regarding the presence of a jet geometry break. We investigated the jet width profile of CTA 102 to study the possible transition changes in the jet, thereby improving the understanding of connection between Bondi radius and jet transition. We used multi-frequency VLBA images of CTA 102 at 2, 5, and 8 (single epoch), and 15, 22 and 43 GHz (stacked). The jet width profile was modeled with a single power law $W_{jet}\propto r^{\epsilon}$ yielding a power-law index of $\epsilon=0.69\pm0.02$, indicative of a quasi-parabolic geometry with no clear transition to a conical regime. The absence of discernible structural break around the Bondi radius implies that the physical conditions associated with the radius alone are insufficient to explain the jet collimation behaviour. On the other hand, we observe oscillatory features in the jet width profile, suggesting the influence of additional physical processes beyond gravitational confinement. These findings contribute to a more nuanced understanding of jet collimation in AGN and highlight the complexity of jet-environment interactions.

To understand the underlying mechanisms for high lithium abundances among core He-burning or red clump (RC) giants, we analyzed a sample of 5227 RC giants of mass M $\leq$ 2~M$_{\odot}$ using spectra and asteroseismic data. We found 120 RC giants ($\sim$2~$\%$) with a lower limit of A(Li) = 0.7~dex, a factor of 40 more than their predecessors close to the RGB tip. Of the 120 RC giants, we could measure actual rotations for 16 RC giants using stellar spots from the Kepler light curve analysis. We found that most of the high rotation RC giants are also very high Li-rich RC giants, and the rotation seems to decline rapidly with Li abundance depletion, suggesting that both the high rotation and high Li abundance are transient phenomena and associated with a single source. Further, we found a significantly high occurrence of 15~$\%$ and 12~$\%$ of Li-rich RC giants among extremely low-mass RC giants and RC giants with anomalous [C/N] ratios, respectively. The extremely low mass, fast rotation and anomalous [C/N] values of RC giants are attributed to their past binary interaction/merger history. The results pose a question of whether the binary interaction/merger is a prerequisite along with the He-flash for Li-enhancement among RC giants.

In recent years, a significant number of observatories and universities have been planning to construct optical and infrared telescopes at the Lenghu site in Qinghai Province due to the site's excellent seeing and clear night sky fraction. Although astronomical performances of the Lenghu site have been reported in detail by numerous papers, there were few reports showing statistics of temperature and wind characteristics in the traditional way required for the design of steel structures of large astronomical telescopes and enclosures, as well as the ventilation and air conditioning systems of these enclosures. This paper aims to present such new statistical data on temperature and wind conditions at the site, which could be helpful to inform and aid in such design decisions at the Lenghu site

Our aim is to investigate the protostellar jets inside the young stellar object (YSO) cluster G105.42+9.88 (alias LkH$\alpha$ 234). This is one of the least luminous targets of the Protostellar Outflows at the EarliesT Stages (POETS) survey, which has been recently carried out to study young outflow emission on scales of 10-100 au. The combination of multi-epoch water maser very long baseline interferometry (VLBI) observations with sensitive Jansky Very Large Array (JVLA) continuum and Large Binocular Telescope (LBT) H$_2$ 2.12 $\mu$m observations, allows us to study the protostellar outflows from the intermediate-mass binary system VLA 3A and 3B, separated by ~0.22", and from VLA 2, an intermediate-mass YSO placed ~1" to northwest of VLA 3. Toward VLA 2, the 2001 and 2011 Very Long Baseline Array (VLBA) observations consistently show that the water masers are tracing a jet. The analysis of the 3D flow velocities proves that the jet is magneto-centrifugally launched in a magnetohydrodynamic (MHD) disk wind (DW). We infer launch radii in the range 10-50 au for the streamlines traced by the water masers. The global VLBI 2023 water maser observations indicate that the jet propagation can be hindered by a very dense clump placed northeast of VLA 2 and that is consistent with the large-scale LBT H$_2$ emission, tracing only the southwest lobe of the VLA 2 jet. Instead, the parallel jets emitted by the nearby YSOs VLA 3A and 3B can be reliably tracked with the H$_2$ emission at scales of a few 10" to both the southwest and the northeast. In particular, northeast of VLA 3 the direction of these two jets crosses a linear chain of spaced H$_2$ knots, which is a clear signature of an episodic jet. The variable ejection from VLA 3B, witnessed by the water masers at scales of ~10 au, could be the origin of the episodic jet observed at larger scales.

The pulsation of white dwarfs provides crucial information on stellar parameters for understanding the atmosphere and interior structure of these stars. In this study, we present a comprehensive statistical analysis of known ZZ Ceti stars from historical literature. Our dataset includes stellar parameters and oscillation properties from 339 samples, with 194 of them having undergone asteroseismological analysis. We investigated the empirical instability strip of ZZ Ceti stars and confirmed the linear relationship between temperature and weighted mean pulsation periods (WMP). We found that the WMP distribution is well-described with two groups of stars with peak values at $\sim254$ s and $\sim719$ s. Using seismic mass and trigonometrical radii derived from GAIA DR3 parallaxes, we tested the mass-radius relationship of white dwarfs through observational and seismic analysis of ZZ Cetis. They are generally larger than the theoretical values, with the discrepancy reaching up to $\sim15\%$ for massive stars with a mass estimated by seismology.

The Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures (QUARKS) survey observed 139 infrared-bright (IR-bright) massive protoclusters at 1.3 mm wavelength with ALMA. This study investigates clump-to-core fragmentation and searches for candidate high-mass starless cores within IR-bright clumps using combined ALMA 12-m (C-2) and Atacama Compact Array (ACA) 7-m data, providing $\sim$ 1 arcsec ($\sim\rm0.02~pc$ at 3.7 kpc) resolution and $\sim\rm0.6\,mJy\,beam^{-1}$ continuum sensitivity ($\sim 0.3~M_{\odot}$ at 30 K). We identified 1562 compact cores from 1.3 mm continuum emission using getsf. Observed linear core separations ($\lambda_{\rm obs}$) are significantly less than the thermal Jeans length ($\lambda_{\rm J}$), with the $\lambda_{\rm obs}/\lambda_{\rm J}$ ratios peaking at $\sim0.2$. This indicates that thermal Jeans fragmentation has taken place within the IR-bright protocluster clumps studied here. The observed low ratio of $\lambda_{\rm obs}/\lambda_{\rm J}\ll 1$ could be the result of evolving core separation or hierarchical fragmentation. Based on associated signatures of star formation (e.g., outflows and ionized gas), we classified cores into three categories: 127 starless, 971 warm, and 464 evolved cores. Two starless cores have mass exceeding 16$\,M_{\odot}$, and represent high-mass candidates. The scarcity of such candidates suggests that competitive accretion-type models could be more applicable than turbulent core accretion-type models in high-mass star formation within these IR-bright protocluster clumps.

Giant impacts were common in the early evolution of the Solar System, and it is possible that Venus also experienced an impact. A giant impact on Venus could have affected its rotation rate and possibly its thermal evolution. In this work, we explore a range of possible impacts using smoothed particle hydrodynamics (SPH). We consider the final major collision, assuming that differentiation already occurred and that Venus consists of an iron core (30% of Venus' mass) and a forsterite mantle (70% of Venus' mass). We use differentiated impactors with masses ranging from 0.01 to 0.1 Earth masses, impact velocities between 10 and 15 km/s, various impact geometries (head-on and oblique), different primordial thermal profiles, and a range of pre-impact rotation rates of Venus. We analyse the post-impact rotation periods and debris disc masses to identify scenarios that can reproduce Venus' present-day characteristics. Our findings show that a wide range of impact scenarios are consistent with Venus' current rotation. These include head-on collisions on a non-rotating Venus and oblique, hit-and-run impacts by Mars-sized bodies on a rotating Venus. Importantly, collisions that match Venus' present-day rotation rate typically produce minimal debris discs residing within Venus' synchronous orbit. This suggests that the material would likely reaccrete onto the planet, preventing the formation of long-lasting satellites - consistent with Venus' lack of a moon. We conclude that a giant impact can be consistent with both Venus' unusual rotation and lack of a moon, potentially setting the stage for its subsequent thermal evolution.

Observing large scale structure in redshift space gives rise to the well known redshift space distortions whereby a spherical distribution of galaxies is distorted into an ellipsoid along the line of sight of the observer. This effect is important on linear scales and so can be thought of as a Newtonian correction to the density perturbation even though their physical origin is in the Doppler effect. On larger scales subtler aspects of the Doppler and gravitational redshift effects give rise to further distortions in redshift space. These further contort objects beyond an ellipsoidal compression, into shapes with broken line-of-sight symmetry such as an egg- or bean-like shapes. In this paper, we aim to qualitatively picture how large over-dense regions, including clusters or superclusters, and under-dense regions, such as voids, undergoing infall or outflow respectively, become distorted in redshift space when higher-order relativistic effects are taken into account. This will contribute when analysing structure in real space such as stacking voids which are no longer radially symmetric when these effects are included.

In order to compress and more easily interpret Lyman-$\alpha$ forest (Ly$\alpha$F) datasets, summary statistics, e.g. the power spectrum, are commonly used. However, such summaries unavoidably lose some information, weakening the constraining power on parameters of interest. Recently, machine learning (ML)-based summary approaches have been proposed as an alternative to human-defined statistical measures. This raises a question: can ML-based summaries contain the full information captured by traditional statistics, and vice versa? In this study, we apply three human-defined techniques and one ML-based approach to summarize mock Ly$\alpha$F data from hydrodynamical simulations and infer two thermal parameters of the intergalactic medium, assuming a power-law temperature-density relation. We introduce a metric for measuring the improvement in the figure of merit when combining two summaries. Consequently, we demonstrate that the ML-based summary approach not only contains almost all of the information from the human-defined statistics, but also that it provides significantly stronger constraints by a ratio of better than 1:3 in terms of the posterior volume on the temperature-density relation parameters.

We study the interplay between mass-loss and dynamical friction (DF) on the orbital decay of the Fornax dwarf spheroidal galaxy in the potential of the Milky Way (MW). Using a simplified single particle approach combined with a mass-loss rate extrapolated by $N-$body simulations we find that the the effect of a time-dependent mass partially compensates DF, and typically produces a much less evident decay of the pergalactic distance, thus confirming that $N-$body simulations in smooth MW potentials without DF can be taken as a good model of the dynamics of dwarf satellite galaxies.

Galaxy image translation is an important application in galaxy physics and cosmology. With deep learning-based generative models, image translation has been performed for image generation, data quality enhancement, information extraction, and generalized for other tasks such as deblending and anomaly detection. However, most endeavors on image translation primarily focus on the pixel-level and morphology-level statistics of galaxy images. There is a lack of discussion on the preservation of complex high-order galaxy physical information, which would be more challenging but crucial for studies that rely on high-fidelity image translation. Therefore, we investigated the effectiveness of generative models in preserving high-order physical information (represented by spectroscopic redshift) along with pixel-level and morphology-level information. We tested four representative models, i.e. a Swin Transformer, an SRGAN, a capsule network, and a diffusion model, using the SDSS and CFHTLS galaxy images. We found that these models show different levels of incapabilities in retaining redshift information, even if the global structures of galaxies and morphology-level statistics can be roughly reproduced. In particular, the cross-band peak fluxes of galaxies were found to contain meaningful redshift information, whereas they are subject to noticeable uncertainties in the translation of images, which may substantially be due to the nature of many-to-many mapping. Nonetheless, imperfect translated images may still contain a considerable amount of information and thus hold promise for downstream applications for which high image fidelity is not strongly required. Our work can facilitate further research on how complex physical information is manifested on galaxy images, and it provides implications on the development of image translation models for scientific use.

The majority of Galactic globular star clusters (GCs) have been reported to contain at least two populations of stars (we use P1 for the primordial and P2 for the chemically-enriched population). Recent observational studies found that dynamically-old GCs have P1 and P2 spatially mixed due to relaxation processes. However, in dynamically-young GCs, where P2 is expected to be more centrally concentrated from birth, the spatial distributions of P1 and P2 are sometimes very different from system to system. This suggests that more complex dynamical processes specific to certain GCs might have shaped those distributions. We aim to investigate the discrepancies between the spatial concentration of P1 and P2 stars in dynamically-young GCs. Our focus is to evaluate whether massive binary stars (e.g. BHs) can cause the expansion of the P2 stars through binary-single interactions in the core, and whether they can mix or even radially invert the P1 and P2 distributions. We use a set of theoretical and empirical arguments to evaluate the effectiveness of binary-single star scattering. We then construct a set of direct N-body models with massive primordial binaries to verify our estimates further and gain more insights into the dynamical processes in GCs. We find that binary-single star scatterings can push the central P2 stars outwards within a few relaxation times. While we do not produce radial inversion of P1 and P2 for any initial conditions we tested, this mechanism systematically produces clusters where P1 and P2 look fully mixed even in projection. The mixing is enhanced 1) in denser GCs, 2) in GCs containing more binary stars, and 3) when the mass ratio between the binary components and the cluster members is higher. Binary-single star interactions seem able to explain the observable properties of some dynamically-young GCs (e.g. NGC4590 or NGC5904) where P1 and P2 are fully radially mixed.

In the last few years Intensity Interferometry (II) has made significant strides in achieving high-precision resolution of stellar objects at optical wavelengths. Despite these advancements, phase retrieval remains a major challenge due to the nature of photon correlation. This paper explores the application of a conditional Generative Adversarial Network (cGAN) to tackle the problem of image reconstruction in Intensity Interferometry. This approach successfully reconstructs the shape, size, and brightness distribution of a fast-rotating star from sparsely sampled, spatial power spectrum of the source, corresponding to II with four telescopes. Although this particular example could also be addressed using parameter fitting, the results suggest that with larger arrays much more complicated systems could be reconstructed by applying machine-learning techniques to II.

We present the first first X-ray polarization measurements of a white dwarf, the intermediate polar EX Hya. We measured significant polarization only in the 2 -- 3 keV energy band with a polarization degree of 8 percent at a $3\sigma$ significance. No significant polarization was detected above 3 keV, which we attribute to the higher energy bands having lower signal-to-noise. We found that the scattering surface detected by the IXPE is nearly perpendicular to the optical scattering plane, showing that the X-ray scattering surface is the WD and close to the base of the accretion column. Finally, we show how the polarization can be used to estimate the height of the accretion shock above the white dwarf's surface.

X-ray and EUV solar flare emission cause increases in the Earth's dayside ionospheric electron density. While the response of the lower ionosphere to X-rays is well studied, the delay between EUV flare emission and the response of the ionospheric F-region has not been investigated. Here, we calculate the delays between incident He II 304 Angstrom emission, and the TEC response for 10 powerful solar flares, all of which exhibit delays under 1 minute. We assess these delays in relation to multiple solar and geophysical factors, and find a strong negative correlation (-0.85) between delay and He II flux change and a moderate negative correlation (-0.55) with rate of increase in He II flux. Additionally, flare magnitude and the X-ray-to-He II flux ratio at peak He II emission show strong negative correlations (-0.80 and -0.75, respectively). We also identify longer delays for flares occurring closer to the summer solstice. These results may have applications in upper-ionospheric recombination rate calculations, atmospheric modelling, and other solar-terrestrial studies. We highlight the importance of incident EUV and X-ray flux parameters on the response time of the ionospheric electron content, and these findings may also have implications for mitigating disruptions in communication and navigation systems.

This letter presents hybrid and fully kinetic particle-in-cell simulations of fast-mode compressible turbulence. Turbulence damping at magnetohydrodynamic (MHD) scales closely follows linear transit-time damping theory. Despite strong phase steepening, turbulence sustains robust cross-scale energy cascading. These findings resolve the long-standing question about the validity of classical wave theories in strongly nonlinear regimes and overturn the common presumption that wave steepening disrupts compressible turbulence cascade, thereby providing a more complete picture of MHD turbulence.

Polycyclic aromatic hydrocarbons (PAHs) and carbonaceous dust have been observed in clumpy circumstellar environments, yet their formation and evolutionary pathways in such environments remain elusive. We aim to characterize the PAH emission in a clumpy planetary nebula to decipher their formation and evolution pathways. We obtained JWST Near-Infrared Spectrograph (NIRSpec) and Mid-Infrared Instrument (MIRI) integral field unit spectroscopic observations of two individual knots in the Ring Nebula (NGC 6720), a clumpy planetary nebula, and determine the PAH spectral characteristics. We detect the 3.3 and 11.2 um PAH emission bands in both knots but do not detect PAH emission in the 6-9 um range. We supplement our data with Spitzer Infrared Spectrograph (IRS) Short-Low 1 (SL1) and SL2 data, containing 11.2, weak 6.2, and weak 7.7 um PAH emission bands. The JWST data confirm the unusual profile of the 11.2 um band, which is very broad and redshifted with respect to typical 11.2 um PAH profiles. We estimate the PAH population to be largely neutral. The relative integrated surface brightness of the 3.3 and 11.2 um bands indicates the presence of small-sized PAHs, consisting of 35 +/- 6 carbon atoms. We find that the PAH emission is concentrated outside of the clumps, in the inter-clump medium, and confirm the existence of enhanced PAH emission in a narrow 'PAH ring' centred on the central star. This morphology suggests that PAHs formed during the Ring Nebula's asymptotic giant branch phase, in the central star's dust-driven wind.

A sample of high-frequency peaker (HFP) candidates was formed from the AT20G catalog radio sources with spectral indices of the optically thick emission region $\alpha_{below}$ exceeding +0.5. A study of the spectral properties of the sources in the sample, which included 269 radio sources, was performed. The spectra of the sources were constructed and the spectral indices below $\alpha_{below}$ and above the peak $\alpha_{above}$, the peak frequency $\nu_{obs}$, the flux density at the peak frequency $S_{peak}$, and the peak half-width in the radio spectrum were determined. Analysis of the spectra showed that the sample is fairly homogeneous and consists of HFPs with $\nu_{obs}>5$ GHz. Most sources (67%) do not have data at frequencies below 0.8 GHz. 187 sources have ultra-inverted spectra ($\alpha_{below}>$+0.7), which is 3.2% of all sources in the AT20G catalog and 70% of radio sources in our sample. Optical identification of radio sources in the sample showed that 70% of the hosts are quasars. The sample consists of compact objects with radio luminosity at 20 GHz in the range of $10^{23}$-$10^{30}$ W/Hz, angular sizes of emitting regions of radio sources are 0.002-0.25 mas, projected linear sizes are from 0.2 to 30 pc. The dependence of the peak frequencies of radio sources on their angular sizes is in good agreement with that previously discovered for CSS and GPS sources.

We perform a suite of numerical simulations of tidal disruption events, using smoothed particle hydrodynamics, for a close binary system consisting of two low-mass white dwarfs, and an intermediate mass non-spinning black hole. The binary components are considered to be detached and on the same plane with the black hole. Our results quantify how the outcomes of these events depend crucially on the positional configuration of the binary components at the orbital pericenter, and we also show how distinctive behaviour for non-identical mass binaries arise, as compared to identical ones. We highlight these differences on observables such as mass fallback rates, kick velocities and gravitational waves, and also compute clump formation time within the stellar debris. In our setup, prograde binary motion, where the angular momentum of the binary is in the same direction as that of the center of mass motion around the black hole, is qualitatively similar to multiple events of single star tidal disruptions. However, we argue that interactions between stellar debris in the corresponding retrograde scenarios result in different and distinct outcomes. Our results should serve as indicative benchmarks in the observational aspects of tidal interactions between close white dwarf binaries and intermediate mass black holes.

Orbital maneuver planning is a critical aspect of mission design, aimed at minimizing propellant consumption, which is directly correlated with the total velocity change ($\Delta V$). While analytical solutions like the Hohmann and Bi-elliptic transfers offer optimal strategies for specific cases, they lack the flexibility for more general optimization problems. This paper presents a computational framework that couples a Genetic Algorithm (GA) with the Poliastro orbital mechanics library to autonomously discover fuel-optimal, three-impulse transfer trajectories between coplanar circular orbits. We validate this framework across two distinct scenarios: a low-energy transfer from Low Earth Orbit (LEO) to a Geostationary Orbit (GEO), and a high-energy transfer to a distant orbit with a radius 20 times that of LEO. Our results demonstrate the framework's remarkable adaptability. For the LEO-to-GEO transfer, the GA precisely converges to the classical Hohmann transfer, achieving an identical $\Delta V$ of 3853.96 m/s and validating the method's accuracy. Conversely, for the high-energy transfer, the GA identifies a superior Bi-elliptic trajectory that yields a significant $\Delta V$ saving of 213.47 m/s compared to the Hohmann transfer. This fuel efficiency, however, necessitates a trade-off, extending the mission duration from approximately 1 day to over 140 years. This work demonstrates an accessible and powerful toolchain for the rapid prototyping of optimal trajectories, showcasing how combining evolutionary algorithms with open-source libraries provides a robust method for solving complex astrodynamics problems and quantifying their critical design trade-offs.

We perform a detailed observational analysis of several galactic X-ray binaries, focusing on the interplay between black hole spin, jet power, and radiative efficiency within the context of Blandford-Znajek-powered jets. Using updated measurements from continuum fitting and Fe-line methods, we constrain the spin parameter a and the deviation parameter $\beta$ for five key black hole systems: H1743-322, XTE J1550-564, GRS 1124-683, GRO J1655-40, and GRS 1915+105. For each system, we compare the allowed parameter spaces derived independently from observed radiative efficiencies and emitted jet powers under different assumptions for the jet Lorentz factor $\Gamma=2,5$. By overlapping these observational constraints with theoretical expectations for regular black holes, we assess the viability of various spin-deviation combinations in explaining the observed phenomena. Our results reveal significant restrictions on the allowed values of $\beta$, with typical upper bounds around 0.38 - 0.4, except for rapidly spinning sources where the constraint becomes notably tighter. We further present a modified method for generating rotating solutions from static regular black hole spacetimes and provide a robust theoretical framework for relating jet power to black hole angular frequency in curved geometries. We also find that the theoretical jet power is modified by regularization factor for regular black holes. These findings place stringent observational bounds on deviations from the Kerr geometry and provide important insight into the astrophysical mechanisms powering accreting stellar-mass black holes.

The knowledge of the X-ray properties of the hot gas halos of early-type galaxies has significantly advanced in the past years, for large and homogeneously investigated samples. We compare these results with the X-ray properties of an exploratory set of gas evolution models in realistic early-type galaxies, produced with our high-resolution 2D hydrodynamical code MACER that includes AGN feedback and accretion from a circumgalactic medium. The model X-ray emission and absorption are integrated along the line of sight, to obtain maps of the surface brightness Sigma_X and temperature Tx. The X-ray diagnostics considered are the luminosity and average temperature for the whole galaxy (Lx and <Tx>) and within 5 optical effective radii (Lx5 and <Tx5>), and the circularized profiles Sigma_X(R) and Tx(R). The values for Lx, Lx5, <Tx>, and <Tx5> compare very well with those observed. The Sigma_X(R) and Tx(R) also present qualitative similarities with those of the representative galaxy NGC5129, and of ETGs with the most commonly observed shape for Tx(R): Sigma_X(R) matches the observed profile over many optical effective radii Re, and Tx(R) reproduces the characteristic bump that peaks at R=(1 - 3)Re. Inside the peak position, Tx(R) declines towards the center, but the explored models are systematically hotter by ~30%; possible explanations for this discrepancy are discussed. Interestingly, Sigma_X(R) and Tx(R) as large as observed outside of R~Re are reproduced only with significant accretion from a circumgalactic medium, highlighting its importance.

At certain radii protoplanetary discs may sustain a form of oscillatory convection (`convective overstability'; COS) due to localised adverse entropy gradients. The resulting hydrodynamical activity can produce coherent structures, such as zonal flows and vortices, that may concentrate solid material and aid their further coagulation. In this paper we extend previous axisymmetric runs by performing local three-dimensional simulations of the COS, using the code SNOOPY. As parameters are varied, we characterise how the various axisymmetric COS saturated states are transformed in 3D, while also tracking their interrelationship with the subcritical baroclinic instability. In particular, at low Reynolds number (Re) our 3D simulations exhibit similar weakly nonlinear and wave turbulent states to our earlier axisymmetic runs. At higher Re, but low Peclet number (Pe), we obtain bursty cycles involving the creation of zonal flows, the subsequent development of planar vortices, and their destruction by elliptical instability. For larger Pe, however, zonal flows can persist, alongside weaker more elongated vortices. These results further reveal the diversity of the COS's behaviour, and show that solid accumulation via COS-induced vortices may not be straightforward.

We present a systematic statistical analysis of an informal astrophysical phenomenon known as Renzo's rule (or Sancisi's law), which states that "for any feature in a galaxy's luminosity profile, there is a corresponding feature in the rotation curve, and vice versa." This is often posed as a challenge for the standard LCDM model while supporting alternative theories such as MOND. Indeed, we identify clear features in the dwarf spiral NGC 1560 -- a prime example for Renzo's rule -- and find correlation statistics which support Renzo's rule with a slight preference for MOND over LCDM halo fits. However, a broader analysis on galaxies in the SPARC database reveals an excess of features in rotation curves that lack clear baryonic counterparts, with correlation statistics deviating up to $3\sigma$ on average from that predicted by both MOND and LCDM haloes, challenging the validity of Renzo's rule. Thus we do not find clear evidence for Renzo's rule in present galaxy data overall. We additionally perform mock tests, which show that a definitive test of Renzo's rule is primarily limited by the lack of clearly resolved baryonic features in current galaxy data.

The meteoritical community widely assumes that the probability of finding two meteorites from different falls laying in close proximity is negligible. However, recent studies have suggested that spatiotemporal coincidences may be critical when associating a meteorite with a witnessed fall. In this work, we estimate the number of accumulated meteorites--those resulting from past falls--that are present in landing regions of new falls, while accounting for the effects of terrestrial weathering. We present a simple, fast-computing model to estimate such probability, validated with a Monte Carlo approach based on dark flight computations from real meteorite-dropping fireball data. Considering meteorite masses higher than 10 g, our results indicate that in regions with minimal weathering, like Antarctica, the probability of encountering a previous meteorite within a new fall strewn field may be as high as 75%. In environments with higher weathering rates, like countryside or urban regions, this probability decreases to <1%. When considering the 30 g Lake Frome 006 meteorite coincidence case, the probability of recovering a non-related meteorite with an age of 3.2 kyr from a 0.7 km^2 search area is 6.9%. In the case of the 1 kg Ischgl meteorite, the probability of coincidence with another fresh meteorite of similar mass is 0.06% assuming a large strewn field of 210 km^2. Applied to the Almahata Sitta case, our model predicts a 11.3% of coincidence with a previous meteorite fall. Our results strongly suggest that isotopic dating is essential before associating any meteorite with a witnessed fall.

The black hole (BH) spin could significantly change the density of dark matter (DM) in its vicinity, creating a mini-spike of the density of DM. The dynamical friction (DF) between DM and the companion star of a BH can provide an efficient loss of angular momentum, driving the BH-main sequence (MS) star binary to evolve toward a compact orbit system. We investigate the influence of the DF of DM on the detectability of intermediate-mass black hole (IMBH)-MS binaries as low-frequency gravitational wave (GW) sources. Taking into account the DF of DM, we employ the detailed binary evolution code MESA to model the evolution of a large number of IMBH-MS binaries. Our simulation shows that the DF of DM can drive those IMBH-MS binaries to evolve toward low-frequency GW sources for a low donor-star mass, a high spike index, or a short initial orbital period. When the spike index $\gamma=1.60$, those IMBH-MS binaries with donor-star masses of $1.0-3.4~ M_{\odot}$ and initial orbital periods of $0.65-16.82~ \rm days$ could potentially evolve into visible LISA sources within a distance of $10~\rm kpc$. The DF of DM can enlarge the initial parameter space and prolong the bifurcation periods. In the low-frequency GW source stage, the X-ray luminosities of those IMBH X-ray binaries are $\sim 10^{35}-10^{36}~\rm erg\,s^{-1}$, hence they are ideal multimessenger objects.

Using advanced processing techniques, we analyze high-cadence, high-resolution extreme ultraviolet images and show that, throughout the solar cycle, mid-latitude coronal holes (CHs) are made up of ubiquitous and space-filling funnel-shaped structures (or cells) anchored to unipolar magnetic flux concentrations in network lanes. We demonstrate that the coronal cells, previously documented in the magnetically closed regions, as well as coronal plumes, inside CHs, are a particular manifestation of ubiquitous cells. The cell properties depend on the magnetic field intensity at their footpoint and connectivity in the corona, either closing in opposite polarity regions (CF-cells) or extending to form open-field (OF-cells). The OF-cells reach size scales on the order of super-granules and are characterized by dark lanes delimiting ray-like features both showing, at different levels, persistent jet-like ejections. The cells' lifetime mirrors that of magnetic flux concentrations revealed by magnetograms, slowly emerging and then disappearing in a matter of a few hours to a few days in a one-to-one correspondence. When a cell forms along the CH boundary, it can alter the CH boundary by shrinking or expanding the CH by an approximately supergranular cell unit. Therefore, coronal cells can contribute to the dynamics of CH boundary. We contextualize these observations in a "coronal cell" theory potentially able to provide an explanation for fine scale coronal structures and jetting activity in polar coronal holes.

We propose a new model for the origin of Fast Radio Bursts (FRBs), attributing these phenomena to sudden discharges of accumulated electric charge in the accretion disk of compact objects such as black holes. Our framework demonstrates how Compton scattering within the disk plasma generates charge separation, creating a capacitor-like system stabilized by the equilibrium between radiation pressure and electrostatic forces. We detail the discharge process through destabilizing mechanisms in this capacitor, resulting in radiative emission. We compare our model's prediction on radiation signatures with observational data, using FRB2018725A as an example to obtain key quantitative relationships. Additionally, we estimate the total charge buildup via Compton scattering for a stellar-mass black hole, constrained by the best-fit between our model and observations, and determine the corresponding electron density in the accretion disk for this mechanism to operate.

We perform two-dimensional global magnetohydrodynamic (MHD) simulations including the full nonideal MHD effects (Ohmic diffusion, Hall effect, and ambipolar diffusion) and approximate radiation transport to understand the dynamics and thermal structure of the inner protoplanetary disks (PPDs). We have developed a simple radiative transfer model for PPDs that reasonably treats stellar non-thermal (XUV), stellar thermal (optical/infrared), and re-emitted radiations, reproducing the temperature structures from Monte Carlo radiative transfer. Our simulations show fast one-sided surface accretion ($\sim 10\%$ of Keplerian velocity) and asymmetric disk winds when the vertical magnetic field is aligned with the disk angular momentum. The asymmetry is due to the failure of the wind on the side with the accretion layer. On the accreting surface, clumps are repeatedly generated and accrete, driven by radiative feedback. For the anti-aligned fields, surface accretion becomes more moderate and time-variable, while the winds remain largely symmetric. For the thermal structure, accretion heating does not affect the disk temperature in any of our runs. This is because (1) the accretion energy dissipates via Joule heating at 2--3 gas scale heights, where low optical depth enables efficient radiative cooling, and (2) the winds remove $\gtrsim 10\%$ of the accretion energy. In contrast, the winds enhance radiative heating by elevating the irradiation front. These results highlight the importance of coupling between gas dynamics and radiation transport in PPDs, and provide observable magnetic activities such as fast episodic accretion, wind asymmetry, and molecular survival in XUV-irradiated winds.

We present an analysis of the globular cluster (GC) population in the galaxy cluster RXJ 2129.7+0005 (z = 0.234) based on JWST NIRCam imaging in three filters: F115W, F150W, and F200W. We use this material to provide a detailed look at the color-magnitude distribution of the GCs and their spatial distribution around the central giant galaxy. We identified 3,160 GC candidates brighter than F150W=29.5, and assessed photometric completeness through artificial star tests. We determined that the GCs follow a radial power-law distribution with an index of $1.58 \pm 0.04$, with the redder GCs exhibiting a slightly greater central concentration. Their spatial distribution is also highly elliptical, closely following the shape of the BCG halo light.

Binary black holes (BBHs) forming in the accretion disks of active galactic nuclei (AGNs) represent a promising channel for gravitational-wave production. BBHs are typically expected to originate at migration traps, i.e. radial locations where the Type I migration of embedded stellar-mass black holes (BHs) transitions from outwards to inwards. In this work, we test this assumption by explicitly simulating the radial migration of BH pairs in AGN disks under different torque prescriptions, including thermal effects and the switch to Type II migration. We quantify where and when binaries form as a function of supermassive BH (SMBH) mass, disk viscosity, and migrating BH mass. We find that while the majority of pair-up events occur near migration traps, a substantial fraction takes place elsewhere in the disk, particularly for high-viscosity disks ($\alpha=0.1-0.4$) and SMBHs with mass above a threshold of $10^{7.5}$ solar masses, where differential migration is most efficient. The inclusion of thermal torques favors pair-up in outer locations of the disk and facilitates rapid pair-up. We also investigate hierarchical BBH formation, showing that higher-generation pair-ups are more tightly clustered around trap locations. Our results provide realistic prescriptions for BBH pair-up locations and timescales, highlighting the limitations of assuming fixed BBH formation sites.

In the 7 Ms Chandra Deep Field-South catalog, only one source, XID 912, was highly significantly detected in X-rays but had no formally reported counterparts in the UV, optical, infrared, or radio bands. We identified its potential JWST and VLT VIMOS counterparts and measured the corresponding aperture photometry to construct its spectral energy distribution (SED). We fitted this SED using CIGALE. The results indicate that the source is most likely an off-nuclear ultraluminous X-ray source, rather than a background active galactic nucleus.

In most nearby galaxies, photometry of the integrated light of their globular clusters (GCs) has been obtained in only two filters, yielding just a single color index. However, NGC 4874, the brightest central galaxy in the Coma cluster, now has Hubble Space Telescope (HST) photometry available in ten filters, giving us a special opportunity to test SED fitting procedures on GCs in distant galaxies. We fitted 29 of the brightest GCs with a library of SEDs from E-MILES and calculated the best-fit metallicity and mass of each cluster. Using the fitted masses and luminosities derived from the reddest magnitudes, in the flat portion of the GC spectrum, we also calculated inferred mass-to-light ratios for our sample GCs; these were in the range (M/L) $\simeq 2 - 4$, slightly larger than the average values for Milky Way GCs but within the conventional range.

NASA's Lucy spacecraft is en route to conduct the first close encounter with Jupiter's Trojans. While most scheduled flybys lie in the $L_4$ cloud, the only $L_5$ target is the Patroclus-Menoetius binary. Since each flyby offers unique insights into target and population properties unattainable from Earth, we examine the feasibility of including an additional, yet unknown, $L_5$ target while minimizing the impact on Lucy's primary mission. We use the background $L_5$ Trojans brighter than the completeness limit to model their absolute magnitude, spatial, and orbital distributions. A semi-analytical approach estimates the number of Trojans accessible to Lucy for a given $\Delta v$ budget in both pre- and post-Patroclus scenarios. Our results indicate that, while it is unlikely that any suitable Trojan lies on Lucy's nominal path, a moderate $\Delta v$ investment ($35-50\,\mathrm{m/s}$) could enable a sub-kilometer ($500-700\,\mathrm{m}$) flyby prior to the Patroclus encounter. Post-Patroclus, the likelihood of a similar flyby is $\sim60\%$ for $\Delta v\sim$ 50 m/s. Simulations with synthetic Trojans reveal that potential targets cluster near the node opposite to the encounter window, producing an optimal search period in late 2026 for both scenarios. Surveying the densest $10\%$ of this region would require under 5 nights with Subaru/HSC or under 2 nights with Rubin, using shift-and-stack techniques. A successful sub-kilometric flyby would expand Lucy's Trojan target size range and provide new constraints on collisional evolution and the long-standing asymmetry in the $L_4/L_5$ clouds. This nodal-clustering strategy could guide target searches in future Lucy extensions or other planetary flyby missions.

The rate of long-duration gamma-ray bursts (GRBs) from isolated Pop III stars is not well known, as it depends on our poor understanding of their initial mass function (IMF), rotation rates, stellar evolution, and mass loss. A sub-population of massive ($M_{\rm ZAMS}\gtrsim20M_\odot$) Pop III stars is expected to suffer core-collapse and launch a relativistic jet that would power a GRB. In the collapsar scenario, a key requirement is that the pre-supernova star imparts sufficient angular momentum to the remnant black hole to form an accretion disc and launch a relativistic jet, which demands rapid initial rotation of the progenitor star and suppression of line-driven mass loss during its chemically homogeneous evolution. Here we explore a grid of stellar evolution models of Pop III stars with masses $20\leq M_{\rm ZAMS}/M_\odot \leq 100$, which are initially rotating with surface angular velocities $0.6\leq \Omega_0/\Omega_{\rm crit}\leq 0.9$, where centrifugally-driven mass loss ensues for $\Omega>\Omega_{\rm crit}$. Realistic accretion and jet propagation models are used to derive the initial black hole masses and spins, and jet breakout times for these stars. The GRB production efficiency is obtained over a phase space comprising progenitor initial mass, rotation, and wind efficiency. For modest wind efficiency of $\eta_{\rm wind}=0.45-0.35$, the Pop III GRB production efficiency is $\eta_{\rm GRB}\sim10^{-5}-3\times10^{-4}\,M_\odot^{-1}$, respectively, for a top-heavy IMF. This yields an observable all-sky equivalent rate of $\sim2-40\,{\rm yr}^{-1}$ by \textit{Swift}, with 75\% of the GRBs located at $z\lesssim8$. If the actual observed rate is much lower, then this would imply $\eta_{\rm wind}>0.45$, which leads to significant loss of mass and angular momentum that renders isolated Pop III stars incapable of producing GRBs and favours a binary scenario instead.

In the frame of conformal Killing gravity cosmology, we performed a Bayesian analysis on two different datasets of Baryonic Acoustic oscillations (DESI and SDSS DR16) and on two datasets of SNeIa (Pantheon+ and Union3). The results for H0 and Omega_M in a spatially flat FRW background are consistent with the Lambda-CDM scenario. We obtain a non-negligible negative value for the novel density of dark sector, Omega_D, and its relevance in the evolution of the cosmological observables thus finding quantitatively what its contribution is on real data to match the standard scenario. The results confirm the dynamical character of dark energy. We also calculate the deceleration parameter q0 and the present time dark energy equation of state parameter w0: the latter belongs to the quintessence regime. The evaluation of the first acoustic peak of CMB places it extraordinarily near to the best value provided by the Planck collaboration. In this scenario, we can conclude that late time and early time data can be successfully matched under the same standard.

You have a satellite spacecraft or asteroid that moves under the gravitational influence of a massive central body and follows a Keplerian orbit around it ellipse parabola or hyperbola Given measurements of two positions in its orbit what is the family of possible orbital paths that connects them I use the conic section orbits semilatus rectum directly related to orbital angular momentum to parameterise these orbits The solutions have applications to orbit determination ballistic missiles interplanetary interception and targeted reentry I also show how they can be applied to solve the Lambert problem of finding the unique transfer orbit that connects two points in a specified time interval These results are accessible to advanced undergraduate students in physics or aerospace engineering. Supplementary materials are provided online

In the cosmological Robertson-Walker geometry required of the cosmological principle both the Weyl tensor $C^{\mu\lambda\nu\kappa}$ and the Bach tensor $W^{\mu\nu}=[2\nabla_{\kappa}\nabla_{\lambda}-R_{\lambda\kappa}]C^{\mu\lambda\nu\kappa}$ vanish. In general, in perturbations around the cosmological background neither of the fluctuating $\delta C^{\mu\lambda\nu\kappa}$ or $\delta W^{\mu\nu}$ would vanish. However, it is possible for $\delta W^{\mu\nu}$ to vanish even as $\delta C^{\mu\lambda\nu\kappa}$ does not. In this paper we construct an explicit model in which this is the case. The model consists of a tensor gravitational wave fluctuating around a background with a constant negative 3-curvature. The model is exactly solvable and consists purely of geometric quantities with no matter fields at all (i.e., $G^{\mu\nu}=0$, $\delta G^{\mu\nu}=0$, $W^{\mu\nu}=0$, $\delta W^{\mu\nu}=0$, where $G^{\mu\nu}$ is the Einstein tensor). The model can thus be created out of nothing, with creating a universe from nothing thus being an alternative principle to the cosmological principle. The fluctuating gravitational wave contributes to the temperature anisotropy in the cosmic microwave background in a calculable manner, for which we provide a simple analytic way of treating spatial modes that is based on the use of a spatial mode addition theorem. In addition, we provide a treatment of the anisotropy that is based on properties of bandwidth limited functions.

The particle origin of dark matter (DM) remains elusive despite decades of direct, indirect, and collider searches. Several groups have reported a $\gamma$-ray excess toward the Galactic Centre, commonly referred to as the Galactic Centre Excess (GCE). Its spectrum is consistent with annihilation of weakly interacting massive particles (WIMPs) of mass $\mathcal{O}(10-100)$ GeV and a thermal-relic cross section. Although many concrete WIMP models reproduce the GCE spectrum, most are now excluded by direct detection experiments that are approaching the neutrino floor. We investigate a class of anomaly-free extensions of the Standard Model featuring gauged differences of lepton number, $U(1)_{L_i-L_j}$, and gauged baryon minus lepton number, $U(1)_{B-L}$. We show that these models can reproduce the GCE while remaining compatible with the observed relic abundance. We then impose collider and direct detection constraints, accounting for both tree-level and loop-induced kinetic mixing. The $L_\mu-L_e$ model gives the best fit to the GCE: a DM mass of $m_\chi\sim 40-50$ GeV remains consistent with the muon and electron magnetic moment anomalies, $(g-2)_{\mu,e}$, as well as current collider and direct detection limits, for mediator masses in the range $m_{A'}\sim 70-86$ GeV and a DM-mediator coupling of $(1-5)\times10^{-2}$. By contrast, the $L_e-L_\tau$ and $L_\mu-L_\tau$ models yield poorer fits; satisfying both the relic density and experimental bounds forces the DM mass to lie very close to resonance (i.e., approximately half the mediator mass). Finally, while the $B-L$ model also matches the GCE well, its parameter space is almost entirely ruled out by strong direct detection limits, except for the narrow resonance region where $m_\chi$ should be equal to $m_{A'}/2$ requiring a fine-tuning at the few-percent level.

QCD corrections to fermionic Minimal Dark Matter annihilations increase its annihilation cross section (by 2% for a weak doublet, 1.3% for a triplet, 0.5% for a quintuplet) and thereby the the Dark Matter mass required to achieve the observed cosmological relic abundance via thermal freeze-out.

We study tidal Love numbers of static black holes in four-dimensional quadratic theory of gravity, extending the result of GR. We use worldline effective field theory (WEFT) methods to compute metric perturbations from one-point functions, treating the higher-derivative terms perturbatively. We show that insertions of scalar fields on the worldline induce non-zero tidal tails, and the corresponding Love number displays no RG running. The same conclusion holds for the insertions of tensor fields. Furthermore, for scalar dipole perturbations, we derive a Yukawa-deformed Frobenius solution and match the asymptotic behavior to fix the UV charge, finding agreement with EFT predictions of Wilson coefficients. Our work demonstrates that quadratic higher-curvature corrections induce non-zero but scale-independent tidal responses, offering a robust EFT framework to test deviations from GR in gravitational wave observations.

First-order phase transitions in the early Universe are a well-motivated source of gravitational waves (GWs). In this Letter, we identify a previously overlooked GW production mechanism: gravitational transition radiation, arising from graviton emission by particles whose mass changes as they pass through expanding bubble walls. Unlike conventional sources such as bubble collisions or sound waves, this mechanism operates at the microscopic scale set by the Lorentz-contracted wall thickness, leading to GW emission at significantly higher frequencies. The resulting spectrum features a distinctive shape with a peak frequency redshifting to $f_{\rm peak}\sim \gamma_w T_0\sim \gamma_w\times 10^{10}\,{\rm Hz}$ where $\gamma_w$ is the Lorentz boost factor of the wall velocity and $T_0$ is the current temperature of the Universe. This mechanism is generic and is expected to operate similarly for domain walls and other relativistic interfaces.

A flux of ultra-high-energy (UHE) neutrinos is generally expected to be produced by astrophysical sources at cosmological distances and to reach Earth. In this paper, we investigate the impact of neutrino scattering with dark matter (DM) particles in both the intergalactic medium and the Milky Way on the total flux, energy spectrum, and arrival directions of UHE neutrinos. We emphasize the complementarity of neutrino detectors at different latitudes to probe the anisotropy in the flux at Earth due to the attenuation of the neutrino flux in the Milky Way dark matter halo. We also discuss that, with mild astrophysical assumptions, limits on the DM-$\nu$ scattering cross section can be placed even if the neutrino sources are unknown. Finally, we explore all this phenomenology with the recent UHE neutrino event KM3230213A, and place the corresponding limits in the DM-$\nu$ scattering cross-section.

The KAGRA Collaboration has investigated a ten-year upgrade strategy for the KAGRA gravitational wave detector, considering a total of 14 upgrade options that vary in mirror mass, quantum noise reduction techniques, and the quality of cryogenic suspensions. We evaluated the scientific potential of these configurations with a focus on key targets such as parameter estimation of compact binary coalescences, binary neutron star post-merger signals, and continuous gravitational waves. Rather than aiming to improve all science cases uniformly, we prioritized those most sensitive to the detector configuration. Technical feasibility was assessed based on required hardware developments, associated R\&D efforts, cost, and risk. Our study finds that a high-frequency upgrade plan that enhances sensitivity over a broad frequency range above ~200 Hz offers the best balance between scientific return and technical feasibility. Such an upgrade would enable sky localization of binary neutron star mergers at 100 Mpc to better than 0.5 deg$^2$ in a LIGO-Virgo-KAGRA network, and improve the measurement precision of tidal deformability parameter by approximately 10% at median, compared to a network without KAGRA.

This Technical Design Report presents AION-10, a 10-meter atom interferometer to be located at Oxford University using ultracold strontium atoms to make precision measurements of fundamental physics. AION-10 serves as both a prototype for future larger-scale experiments and a versatile scientific instrument capable of conducting its own diverse physics programme. The design features a 10-meter vertical tower housing two atom interferometer sources in an ultra-high vacuum environment. Key engineering challenges include achieving nanometer-level vibrational stability and precise magnetic field control. Solutions include active vibration isolation, specialized magnetic shielding, and a modular assembly approach using professional lifting equipment. Detailed analysis confirms the design meets all performance requirements, with critical optical components remaining within our specifications 97% of the time under realistic operating conditions. Vacuum and vibration measurements in the host building validate that the instrument will achieve the precision needed for quantum sensing applications. This work establishes the technical foundation for scaling atom interferometry to longer baselines while creating a cutting-edge facility for precision measurements that could advance our understanding of fundamental physics.

This paper investigates gravitational lensing in the strong deflection limit, focusing particularly on higher-order images produced near compact objects such as black holes and their observable impact through the visibility function. Employing a robust parametrization framework proposed by Rezzolla and Zhidenko, the study systematically explores deviations from the Schwarzschild metric. A detailed theoretical analysis of interferometric observables is provided, highlighting how higher-order images imprint distinctive, measurable patterns in the visibility function, notably characterized by a staircase-like structure. By parametrically varying metric coefficients, the analysis reveals clear dependencies between spacetime deviations and key observational signatures, specifically the step heights and periodicities in the interferometric visibility. The results enhance the theoretical groundwork for interpreting data from advanced interferometric observations, potentially enabling precise tests of general relativity and the discrimination among alternative gravitational theories.

Computational scientific discovery increasingly relies on algorithms to process complex data and identify meaningful patterns - yet faces persistent challenges in gravitational-wave signal identification. While existing algorithmic approaches like matched filtering (MF) and deep neural networks (DNNs) have achieved partial success, their limitations directly stem from fundamental limitations: MF's excessive computational demands arise from its reliance on predefined theoretical waveform templates, while DNNs' black-box architectures obscure decision logic and introduce hidden biases. We propose Evolutionary Monte Carlo Tree Search (Evo-MCTS), a framework that addresses these limitations through systematic algorithm space exploration guided by domain-aware physical constraints. Our approach combines tree-structured search with evolutionary optimization and large language model heuristics to create interpretable algorithmic solutions. Our Evo-MCTS framework demonstrates substantial improvements, achieving a 20.2\% improvement over state-of-the-art gravitational wave detection algorithms on the MLGWSC-1 benchmark dataset. High-performing algorithm variants consistently exceed thresholds. The framework generates human-interpretable algorithmic pathways that reveal distinct performance patterns. Beyond performance improvements, our framework discovers novel algorithmic combinations, thereby establishing a transferable methodology for automated algorithmic discovery across computational science domains.