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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 19 March

Earth and Planetary Astrophysics

Atmospheric Supply of Hydrogen Cyanide Is Not the Rate-limiting Step for Prebiotic Chemistry across Rocky Exoplanets

Gergely Friss, Paul I. Palmer, Marrick Braam et al. (+1 more)

Hydrogen cyanide (HCN) is crucial for the RNA World hypothesis, forming biomolecules essential for early life. Life likely emerged around 4 billion years ago during the early Archean Eon, a period on Earth with a fainter sun, frequent impacts, and a weakly reducing atmosphere. Warm little ponds (WLPs) are hypothetical protective aqueous environments that help explain the emergence and evolution of fragile prebiotic chemistry in such a hostile environment. WLPs need to undergo cycles of evaporation and rehydration, concentrating prebiotic molecules that increase the likelihood of (de-)polymerisation and forming early RNA molecules. We use a 1-D model of atmospheric chemistry to compare atmospheric HCN delivery to WLPs with exogenous sources. Using early Archean Earth as our baseline, we examine the sensitivity of atmospheric HCN delivery to the atmospheric C/O ratio, semi-major axis, assumed stellar host type, and methane budget, exploring conditions across rocky exoplanets. We find that atmospheric HCN delivery is sensitive to these parameters but its values generally exceed that of meteoritic delivery and our baseline Archean Earth. Planetary atmospheres with higher C/O ratios within the habitable zones of G stars and those closely orbiting M-dwarfs deliver the most atmospheric HCN. We find that atmospheric HCN delivery is remarkably robust, so this molecule is likely not the rate limiting step for the emergence of prebiotic chemistry on rocky exoplanets. This finding, with important caveats, potentially increases the probability of life emerging on other worlds.
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All authors Gergely Friss, Paul I. Palmer, Marrick Braam, Ken Rice

Solar and Stellar Astrophysics

A stray light analysis for SO/PHI-HRT and an updated comparison of the inferred magnetic field with SDO/HMI

Jonas Sinjan, Tino L. Riethmüller, Achim Gandorfer et al. (+6 more)

Context. The High Resolution Telescope of the Polarimetric and Helioseismic Imager on Solar Orbiter (SO/PHI-HRT) operates in an extreme observational environment, observing the Sun as close as $0.28$ au. The high thermal load and large illuminating field puts high demands on the instrument in terms of both imaging performance and false light control. Aims. To characterise the amount of stray light (false light) within SO/PHI-HRT, apply a correction, and re-compare the data products with the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory (SDO/HMI). Methods. We analyse solar limb profiles and a Mercury transit to quantify the amount of stray light and add a correction term when partially reconstructing the SO/PHI-HRT images. For the comparison with SDO/HMI we use data from the 2023 March Solar Orbiter inferior conjunction and compare the magnetic fields on a pixel-by-pixel basis. Results. Increased continuum intensity contrast in the quiet Sun, and darker intensity levels are found in strong magnetic features. Consequently, much stronger fields are inferred in these features. Comparing the stray light corrected data with that from the standard SDO/HMI data products results in a much closer agreement across all vector magnetic field components, particularly when the cadence and noise levels are identical. In most solar features, SO/PHI-HRT infers stronger fields than the SDO/HMI line-of-sight magnetograms. Compared to the vector magnetic field from SDO/HMI the two are very well aligned, with only slight differences in the strongest field regions (where $|\mathbf{B}|>1600$ G or $|\mathbf{B_{\text{LOS}}}|>1300$ G).
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All authors Jonas Sinjan, Tino L. Riethmüller, Achim Gandorfer, Alex Feller, Daniele Calchetti, Francisco J. Bailén, Johann Hirzberger, Gherardo Valori, Sami K. Solanki

Astrophysics of Galaxies

Kinematic diagnostics for non-axisymmetry in the Milky Way's nuclear stellar disc

Karl Fiteni, Xingchen Li, Mattia C. Sormani et al. (+8 more)

There is now strong evidence that the Milky Way (MW) hosts a nuclear stellar disc (NSD). However, whether the NSD is purely axisymmetric or contains a nuclear bar remains unresolved. Since approximately $50\%$ of barred galaxies with MW-like mass in the local Universe host a nuclear bar, investigating whether the MW hosts one is of interest. We conduct a systematic analysis to identify robust kinematic diagnostics capable of determining whether the MW hosts a nuclear bar. Using N-body simulations, we explore the kinematic signatures indicative of a nuclear bar. Using the phase-space coordinates longitude $(\ell)$, latitude $(b)$, proper motions ($\mu_\ell$ and $\mu_{\rm b})$ and line-of-sight velocity $(v_{\rm los})$, we test various diagnostics assuming different nuclear bar orientations. We also evaluate how sample size, dust extinction and bar amplitude influence the efficacy of the diagnostics. We identify two independent kinematic diagnostics capable of revealing a nuclear bar in the MW: (1) the vertex deviation, $l_{\rm v}$, of the ($v_{\ell}-v_{\rm los}$) velocity ellipse; and (2) The asymmetry in the $\mu_{\ell}$ vs $\ell$ distribution. While both are impacted by the sample size and extinction, the vertex deviation proves more robust, especially when combining stars from multiple observational fields. We also assess the correlation between the line-of-sight velocity and the $h_3$ Gauss-Hermite moment ("skewness") of the line-of-sight velocity but find no clear distinction between an NSD and a nuclear bar based on this metric. Our results suggest that data from the current KMOS survey may allow a marginal detection of a nuclear bar using the vertex deviation method. A companion paper provides further validation and detailed analysis of this approach. Nonetheless, future surveys will provide the high quality data necessary to fully exploit the diagnostics outlined in this study.
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All authors Karl Fiteni, Xingchen Li, Mattia C. Sormani, Victor P. Debattista, Arianna Vasini, Francisco Nogueras-Lara, Jason L. Sanders, Nathan Deg, Mathias Schultheis, Marco Donati, Zi-Xuan Feng

Astrophysics of Galaxies

The edge of the Milky Way's star-forming disc: Evidence from a 'U-shaped' stellar age profile

Karl Fiteni, Stuart Robert Anderson, Victor. P. Debattista et al. (+7 more)

We leveraged reliable age and distance estimates from LAMOST-DR3 and APOGEE-DR17+AstroNN combined with \gaia\ data to perform a detailed analysis of the stellar age distribution in the Milky Way's (MW) outer disc using giant stars. Selecting stars near the midplane ($|z|<0.3$ kpc) on near-circular orbits ($\lambda_c > 0.9$), we analysed these independent datasets that employed different age-estimation methods. Our stringent kinematic selection criteria effectively exclude halo stars, ensuring that the observed age trends reflect genuine disc properties rather than contamination from older halo populations. Our results reveal a 'U-shaped' stellar age profile, where a negative gradient in the inner disc transitions to a positive gradient in the outer disc region. We identify the minimum in the stellar age profile at $R_{\rm min}=11.28 \pm 0.58$ kpc and $R_{\rm min}=12.15\pm 0.62$ kpc for the APOGEE-DR17 and LAMOST-DR3 samples, respectively. Using N-body+SPH simulations, we demonstrate that $R_{\rm min}$ corresponds to the break radius in the stellar density profile ($R_{\rm br}$), marking the edge of the Galaxy's star-forming disc. This break arises from a sharp decline in the star formation rate, with the outer positive age gradient produced by the radial migration of stars born inside $R_{\rm br}$. The cessation of star formation in the outer disc might be due to several mechanisms, including the dynamical influence of the bar's outer Lindblad resonance, the onset of the Galactic warp, or thermally regulated star formation. Overall, our results support the picture that the MW has a Type II (down-bending) stellar disc with a break at $R_{\rm br} \approx 11.28-12.15$ kpc, where the combination of star-formation cut-off and radial migration produces the observed U-shaped age profile.
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All authors Karl Fiteni, Stuart Robert Anderson, Victor. P. Debattista, Joseph Caruana, João A. S. Amarante, Steven Gough-Kelly, Laurent Eyer, Leandro Beraldo e Silva, Tigran Khachaturyants, Virginia Cuomo

Astrophysics of Galaxies

ATT12: The Antarctic 12-m Terahertz Telescope for Studies of Dusty Galaxies. I. Instrument Sensitivity and Science Forecasts

Koki Wakasugi, Takuya Hashimoto, Nario Kuno et al. (+13 more)

We present a feasibility study of the Antarctic 12m Terahertz Telescope (ATT12), a next-generation facility to be constructed at New Dome Fuji in Antarctica, designed to open up the FIR and THz windows for extragalactic astronomy. While ATT12 will enable a wide range of Galactic and extragalactic science, this paper focuses on its potential for studies of dusty star-forming galaxies (DSFGs) across cosmic time. Using realistic atmospheric transmission models and the planned instrumental specifications of heterodyne spectrometers and wide-field multi-color continuum cameras, we assess the expected sensitivity and scientific capabilities. We show that spectroscopic observations will enable detections of [CII]158um from galaxies with log(LIR/Lsun)>12 out to z~7, while [OIII]88um will remain observable for HyLIRG-class systems up to z~10. Line ratios including [OIII]52/88um, [NII]122/205um, and [OIII]/[NIII] will provide unique diagnostics of electron density and O/N abundance at z~4-8. Wide-field continuum surveys with the continuum cameras (KIDS-1/2; 300-850 GHz) will reach confusion-limited depths of ~1-2 mJy over ~10,000 deg$^2$, detecting of order $10^{6}$-$10^{7}$ DSFGs with log(LIR/Lsun)>12 at z<5 and $\lesssim10^{3}$–$10^{4}$ HyLIRGs up to z~7 or higher. Higher-frequency cameras (KIDS-3/4; >850 GHz) are designed for targeted follow-up observations and to extend coverage toward the THz regime. Taken together, ATT12 will provide the first statistically representative samples of DSFGs across cosmic time and, through synergy with ALMA, JWST, and the proposed FIR Probe PRIMA, will establish a multi-wavelength framework in which ATT12 discovers large samples through wide-area surveys, ALMA provides high-resolution follow-up of gas and ISM structure, JWST probes stellar populations and metallicity in the rest-frame optical/NIR, and PRIMA delivers ultra-sensitive FIR spectroscopy.
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All authors Koki Wakasugi, Takuya Hashimoto, Nario Kuno, Yu Nagai, Naomasa Nakai, Ken Mawatari, Masumichi Seta, Shun Ishii, Shunsuke Honda, Mana Ito, Hiroshi Matsuo, Makoto Nagai, Yuri Nishimura, Dragan Salak, Kazuo Sorai, Hidenobu Yajima

Earth and Planetary Astrophysics

Dust, gas activity and morphology of comet 12P/Pons-Brooks at heliocentric distances beyond 1.1 au

Marek Husárik, Gulchehra Kokhirova, Valerii Kleshchonok et al. (+6 more)

Comet 12P/Pons-Brooks is a periodic comet with an orbital period of approximately 71 years. Because of the period duration, aphelion of 35.3 au, and highly inclined orbit (74.2 deg), it is classified as a Halley-type comet. In this work, we present the results of the analysis of photometric and spectral observations of comet 12P/Pons-Brooks while it was at a heliocentric distance beyond 1.1 au, before perihelion passage. Quasisynchronous observations were carried out from July 2023 to March 2024 using 0.61-m and 1.3-m telescopes at the Skalnaté Pleso Observatory, 1-m telescope Zeiss-1000 Sanglokh International Astronomical Observatory, and 0.7-m telescope AZT8 at the observation station of Taras Shevchenko National University of Kyiv. Photometric observations were conducted using B, V, and R filters of the Johnson-Cousins and Bessel photometric systems. We completed our data collection with broadband photometric and spectral observations on the 2-m HCT telescope at the Indian Astronomical Observatory. During this period, the dust coma morphology and photometric data measured in the R filter, such as the apparent, absolute magnitudes and dust activity level, indicate several repeated outbursts in brightness and dust activity occurred around July 22, September 25, October 17-23, and a significant outburst was recorded on November 1-7. We detected strong gas emission features in the cometary spectrum belonging to CN, C2, and C3 molecules. Furthermore, gas production rates of these molecules were estimated using Haser's model. A comparison of dust activity level and CN gas production rate shows that dust activity increased significantly as the comet approached the Sun, while gas activity exhibited more moderate changes.
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All authors Marek Husárik, Gulchehra Kokhirova, Valerii Kleshchonok, K. Aravind, Firuza Rakhmatullaeva, Margarita Safonova, Oleksandra Ivanova, Olena Shubina, Arsenii Kasianchuk

Solar and Stellar Astrophysics

Lithium in Wide Binaries: Effective Temperature Governs Depletion while Rotation Plays a Minor Role

Cheng-Cheng Xie, Hai-Jun Tian, Jian-Rong Shi et al. (+1 more)

Using a sample of 116 wide binary systems as coeval and chemically homogeneous stellar pairs, we investigate the factors governing lithium depletion in main-sequence stars. We recover the well-established morphology of the lithium–effective temperature ($T_{\mathrm{eff}}$) relation, including the Li dip (6200–6600\,K), the Li plateau (6000–6200\,K), and a linear trend for cooler stars ($T_{\mathrm{eff}}$ $<$ 6000\,K), where lithium abundance increases by $\sim$0.15\,dex per 100\,K. We demonstrate that the apparent correlation between projected rotational velocity ($v\sin i$) and lithium abundance is secondary to the underlying $T_{\mathrm{eff}}$ dependence; $v\sin i$ is not an independent driver of lithium depletion in our sample. Notably, we identify an anomalous system within the Li dip where the primary star exhibits a $\sim$1.4\,dex lithium excess compared to its secondary companion at nearly identical $T_{\mathrm{eff}}$. We discuss two plausible origins for this anomaly: external enrichment via planetesimal accretion or planetary engulfment, and binary interactions with an unresolved tertiary companion. Our results confirm $T_{\mathrm{eff}}$ as the dominant parameter controlling lithium depletion, while highlighting that additional, non-standard processes can occasionally produce significant lithium enrichment.
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All authors Cheng-Cheng Xie, Hai-Jun Tian, Jian-Rong Shi, Ze-Ming Zhou

Earth and Planetary Astrophysics

Wind accretion onto planets orbiting an evolving Solar-like star and their detectability

P. Padilla-López, R. F. Maldonado, J. A. Toalá et al. (+2 more)

As stars evolve, they undergo significant changes in their physical properties, which can have a profound impact on the planets orbiting them. In particular, the mass lost through stellar wind may be partially accreted by orbiting planets. We present the results of 18 simulations of one-planet systems with planetary masses of 0.5, 1, 2.5, 5, 10, and 13~$\mathrm{M}_\mathrm{J}$, each at initial orbital distances of 5, 10, and 20~AU, orbiting a 2~M$_\odot$ star through its red giant branch and thermally pulsating asymptotic giant branch phases. Our results show that planets with smaller orbits and higher masses accrete more stellar wind material than their wider-orbit and lower-mass counterparts, although the total mass accreted across all simulations remains small compared to their initial planetary mass. Even for the most massive planet, 13 $\mathrm{M}_\mathrm{J}$ at 5 AU, the total mass accreted was $\sim0.56$% of the planet's initial mass; nevertheless, we find that the accretion luminosities of the simulated planets, with the exception of one planet, exceed their expected equilibrium luminosities, suggesting that such emission could be potentially detected. This result is key for the detection of planets around AGB stars, which have no confirmed detections as of yet. We also estimated the accretion and luminosities of two detected two-planet systems over a few orbits, obtaining results consistent with the one-planet simulated systems. Additional tests without wind accretion and with stellar wind drag force showed that, while both have a negligible effect on the orbital evolution, wind accretion remains relevant for the planetary luminosity.
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All authors P. Padilla-López, R. F. Maldonado, J. A. Toalá, E. Tejeda, J. B. Rodríquez-González

Astrophysics of Galaxies

Emission-line Variable Active Galactic Nuclei at Cosmic Noon from HETDEX

Chenxu Liu, Fanchuan Kong, Erin Mentuch Cooper et al. (+11 more)

We present the first statistical census of emission-line variable active galactic nuclei (EVA) at cosmic noon by combining untargeted and deep HETDEX spectroscopy with multi-epoch spectra from SDSS, DESI, and LAMOST. Anchoring all candidates to a HETDEX spectroscopic epoch and requiring AGN classification in either the HETDEX or the external epoch(s), we identify a homogeneous sample of 100 EVA at z~1.5, including 98 newly identified. Emission-line variability is selected primarily through statistically significant line-flux changes, supplemented by extensive visual inspections using contemporaneous photometric light curves. The resulting incidence fraction is $f_{\rm EVA} \approx 0.9\%$. The rest-frame intervals between spectroscopic epochs span $\sim$1–10 yr, with brightening and dimming events exhibiting statistically indistinguishable characteristic timescales ($\Delta T\sim2.2$ and $\sim2.6$ yr, respectively). A key result is the characterization of the Baldwin effect in the time domain: while many EVA follow the ensemble Baldwin effect (eBeff) between two epochs, a substantial fraction exhibit apparent anti-eBeff responses. Time-resolved spectroscopy of an individual source reveals that the intrinsic EW–luminosity relation is non-stationary, with the line-to-continuum responsivity systematically evolving from stronger to weaker across successive variability cycles; sparse two-epoch sampling of this evolving intrinsic Baldwin evolution (iBeff) naturally produces both eBeff-like and anti-eBeff behaviors. Finally, EVA show no strong preference for extreme Eddington ratios but exhibit a mild tendency toward lower $\lambda_{\rm Edd}$ values relative to matched control samples, driven primarily by sources observed in their dim states. Together, these results establish a coherent framework for interpreting emission-line variability in AGN at the peak epoch of cosmic black hole growth.
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All authors Chenxu Liu, Fanchuan Kong, Erin Mentuch Cooper, Dustin Davis, Wei-Jian Guo, Donald P. Schneider, Liang Xu, Karl Gebhardt, Gary J. Hill, Wolfram Kollatschny, Mirko Krumpe, Shiro Mukae, M. C. Powell, Daniel J. Farrow

Instrumentation and Methods for Astrophysics

One-week optical observations of pulsed emission from the Crab pulsar with IMONY on the 3.8 m Seimei telescope

Kazuaki Hashiyama, Takeshi Nakamori, Anju Sato et al. (+13 more)

We report our optical observations of the Crab pulsar using the Imager of MPPC-based Optical photoN counter from Yamagata (IMONY), a high-time-resolution photon-counting imager with 100 ns timing resolution, mounted on the 3.8 m Seimei telescope in Japan (f/D~6). The detector format was upgraded from a $4\times4$ to an $8\times8$ GAPD array with larger pixels ($100$ to $200~{\mu m}$), resulting in a 14".5 field of view on the Seimei telescope. We conducted nightly optical observations for one week, including two nights of simultaneous optical and radio observations with the 64 m Usuda radio telescope. Thanks to the large diameter of the Seimei telescope and the high time resolution of IMONY, we successfully detected optical Single Pulses (SPs) emitted in each rotation. Moreover, we found an optical peak timing drift of $30\pm7.9~\mathrm{\mu s}$ over three days, with a significance of $3.9{\sigma}$. The corresponding emission region size is 9.1 km, which is equivalent to 0.006 times the light cylinder radius of the Crab pulsar. We ruled out the possibility of a pulsar glitch and suggested that the optical pulsed emission region of the Crab pulsar may fluctuate due to the spatial drift and variations in the magnetospheric caustics.
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All authors Kazuaki Hashiyama, Takeshi Nakamori, Anju Sato, Mana Hasebe, Miu Maeshiro, Rin Sato, Tomohiro Sato, Masaru Kino, Kazuhiro Takefuji, Toshio Terasawa, Koji S. Kawabata, Tatsuya Nakaoka, Dai Takei, Masayoshi Shoji, Shota Kisaka, Kazuki Ueno

Astrophysics of Galaxies

UGC 2369S: a Kpc Scale Triple Merger Candidate Identified in a Nearby Luminous Infrared Galaxy

Yuanze Ding, Michael J. Koss, Fiona A. Harrison et al. (+12 more)

We present high spatial resolution ($\lesssim$1.0”), multi-wavelength observations of UGC 2369S, a nearby luminous infrared galaxy showing three distinct cores separated on kpc scales in near-infrared (NIR) imaging with significant X-ray emission. Utilizing optical/NIR adaptive optics (AO), radio, \chandra X-ray, as well as archival HST imaging, we perform a comprehensive study of AGN activity, obscuration, and host properties. As one of the clearest cases of a triple-nucleus merger at $\simeq$3 kpc separations, UGC 2369S is the first to be studied with high-resolution observations at multiple wavelength. We find that the northern core, having possibly the most massive black hole in the system ($\rm M_{BH}\simeq10^{8}\,M_{\odot}$) is consistent with a heavily obscured AGN. However, its high dust extinction ($\rm A_v>5$), hydrogen column density ($N_\mathrm{H}\gtrsim 10^{25}\,\rm cm^{-2}$) and non-detection of optical coronal lines and coronal X-ray emission leave the identification inconclusive. The other two cores show no evidence for black-hole activity and instead exhibit signatures of tidal disruption. From stellar mass surface density and stellar velocity dispersion maps, we infer that the strongly varying gravitational potential in this three-body system may have cannibalized the stellar bulge of the southwestern core, leaving a metal enriched remnant. An ongoing survey focusing on similar triple systems could help us understand how they evolve and help benchmark numerical simulations, providing insight into gravitational wave predictions and the formation of the most massive black holes.
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All authors Yuanze Ding, Michael J. Koss, Fiona A. Harrison, Charles C. Steidel, Connor Auge, Jared Gillette, Erica Hammerstein, Ruancun Li, Macon Magno, Ignacio del Moral-Castro, Alessandro Peca, Claudio Ricci, Yiqing Song, Ezequiel Treister, Zhuyun Zhuang

Astrophysics of Galaxies

SDSS-IV MaNGA: Distinct Structural Growth and Star Formation in Low and High Surface Brightness Disks

Mengting Shen, Jun Yin, Hassen M. Yesuf et al. (+7 more)

We analyze a clean sample of 1,118 late-type, face-on galaxies without AGN contamination from the MaNGA survey. Their photometric structures are quantified via two-component (bulge+disk) decompositions on deep $g$-band images from the DESI Legacy Survey. Using a disk central surface brightness of $\mu_{\rm 0,d,cor}$(g) = 22 $\pm$ 0.3 mag arcsec$^{-2}$ (corrected for inclination and cosmic dimming) as the classification threshold, we identify 159 low surface brightness (LSB) galaxies, 388 LSB candidates, and 571 high surface brightness (HSB) galaxies. LSB galaxies are predominantly low-mass ($M_\ast < 3 \times 10^{10}$ M$_\odot$), exhibiting 29% larger effective radii, 15% lower star formation rates (SFRs), and 12% reduced gas-phase metallicities than HSB counterparts at comparable masses. These differences cause systematic offsets from standard scaling relations. Despite comparable gas content, LSB galaxies host older stellar populations, longer gas depletion times, and less efficient star formation. Spatially resolved analyses further reveal that LSB galaxies display centrally suppressed $\Sigma_{\rm SFR}$, flatter SFR gradients, and rising specific SFR profiles toward their outskirts. Together with steeper negative metallicity gradients, these trends suggest ongoing gas accretion fueling outer-disk star formation. Consistently, the outer regions of LSB galaxies exhibit stronger H$\delta_A$ absorption and lower D$_n$4000 indices, indicating fading A-star populations. Moreover, LSB galaxies show lower $\Sigma_{\ast}$ across all $R/R_e$ and more centrally depleted stellar mass profiles on an absolute radial scale, compared with HSB and large-size star-forming galaxies. Collectively, LSB galaxies represent a distinct population with slow evolution, inefficient star formation, and continued susceptibility to late-time gas accretion and peripheral star formation.
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All authors Mengting Shen, Jun Yin, Hassen M. Yesuf, Lei Hao, Jiafeng Lu, Lin Lin, Chong Ge, Junfeng Wang, Shiyin Shen, Yu Rong

High Energy Astrophysical Phenomena

A systematic search for physical associations between fast radio bursts and astrophysical transients

Hao-Hao Chen, Wen-Tao Xu, Xin-Yu Liang et al. (+2 more)

The physical origin of fast radio bursts (FRBs) remains an unsolved mystery in astrophysics, with the magnetar central engine model as the leading framework. Systematically searching for physical associations between FRBs and the energetic astrophysical transients (ATs) that form magnetars provides a critical test of this scenario, and key clues to FRB progenitors. We perform a systematic search for FRB-AT associations using a sample of 3765 unique FRBs, combining the second CHIME/FRB catalog with 124 additional localized FRBs with measured redshifts. We develop a 3D Bayesian inference framework that jointly incorporates angular separation, positional uncertainty, and redshift constraints to quantify the association probability of candidate pairs. Through spatial cross-matching, we identify 14 FRB-optical transient and 15 FRB-gamma-ray burst (GRB) candidate pairs. Our framework recovers the previously reported high-significance association between FRB 20180916B and AT 2020hur, with an association probability of 0.9998. For the proposed candidate FRB 20190309A and short GRB 060502B, our analysis yields an association probability of 0.83, which is insufficient to claim statistically significant association. No new statistically significant FRB-AT associations are found for all remaining candidates. Our work demonstrates that small angular separation alone is insufficient to confirm FRB-AT associations, and high-precision FRB localization is essential for definitive identification.
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All authors Hao-Hao Chen, Wen-Tao Xu, Xin-Yu Liang, Ming-Xuan Lu, Can-Min Deng

Earth and Planetary Astrophysics

The influence of hypothetical exomoons on planetary thermal phase curves

Xinyi Song, Jun Yang and Yueyun Ouyang

More than 200 moons exist in our Solar System, yet no exomoon has been confirmed to date. While the innermost two planets of the Solar System lack natural satellites and most studies favour the existence of exomoons around long-period planets, some theoretical studies that take tidal dissipation, orbital decay, and migration processes into account suggest that exomoons may survive around short-period exoplanets. We investigated the impact of exomoons on planetary thermal phase curves and assessed their detectability within a theoretical framework. We simulated the thermal phase curves of exomoon-exoplanet systems, including mutual transits and occultations, and explored their dependence on planetary orbital periods across a wide range of systems. Close-in airless exomoons maintain large day-night temperature contrasts, amplifying the thermal phase-curve signal of the system. When the exomoon transits or is occulted by the exoplanet, the transit depth varies with the planetary phase, and the occultation depth varies with the exomoon's phase. The maximum occultation depth can reach $\sim$ 20 ppm for long-period systems. For short-period planets, the signal can reach up to $\sim$100 ppm, although such configurations may not be dynamically stable over long timescales. If exomoons are not accounted for, the planetary temperature distribution retrieved from observed thermal phase curves may overestimate the planetary day-night temperature contrast and underestimate the planetary horizontal heat transport. In principle, the periodic exomoon-exoplanet mutual occultation signal could be extracted using methods such as box-fitting least squares, providing a framework for future observational studies and instrument planning.
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Instrumentation and Methods for Astrophysics

cosmo-numba: B-modes and COSEBIs computations accelerated by Numba

Axel Guinot and Rachel Mandelbaum

Weak gravitational lensing is a widely used probe in cosmological analysis. It allows astrophysists to understand the content and evolution of the Universe. We are entering an era where we are not limited by the data volume but by systematic uncertainties. It is in this context that we present here a simple python-based software package to help in the computation of E-/B-mode decomposition, which can be use for systematic checks or science analysis. As we demonstrate, our implementation has both the high precision and speed required to perform this kind of analysis while avoiding a scenario wherein either numerical precision or computational time is a significant limiting factor.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

QCD and electroweak phase transitions with hidden scale invariance: implications for primordial black holes, quark-lepton nuggets and gravitational waves

Joshua Cesca and Archil Kobakhidze

We study the cosmological implications of the minimal non-linear realisation of scale invariance within the Standard Model (SM). This framework provides a technically natural explanation for the hierarchy between the Planck scale and the electroweak scale and introduces only a light, feebly coupled dilaton field beyond the SM particles. Although the model is almost indistinguishable from the minimal SM at low energies, its cosmological consequences differ dramatically. In particular, the electroweak Higgs field remains trapped in the symmetric phase until the Universe cools to very low temperatures, $T_c^{(\chi)}\sim 28$ MeV, where the first-order QCD chiral symmetry-breaking phase transition triggers the electroweak phase transition. This scenario offers intriguing possibilities for the production of primordial black holes, low-frequency gravitational waves, and multi-quark and lepton nuggets, which we explore in some detail using simplified approximations.
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Earth and Planetary Astrophysics

A Warm Massive Pair of Planets around TOI-1232 Revealed with Transit-timing Variations and Doppler Spectroscopy

Deyan P. Mihaylov, Jan Eberhardt, Trifon Trifonov et al. (+32 more)

TOI-1232 is a G-dwarf star with a mass of $1.06_{-0.06}^{+0.07} M_\odot$, a radius of $1.07\pm 0.05 R_\odot$, and slightly higher metallicity than solar of Fe/H = $0.18 \pm 0.05$. The star hosts a transiting warm Jovian-mass planet, TOI-1232 b, with an orbital period of $P_{b} = 14.256_{-0.001}^{+0.001}$ days, identified with data from multiple sectors of the $\textit{TESS}$ space telescope. The $\textit{TESS}$ light curve of TOI-1232 is complex, as it is contaminated by a background eclipsing binary with a period of $1.37$ days. The TOI-1232 b was firmly confirmed by ground-based transit follow-up campaigns from Las Cumbres, Hazelwood, Brierfield, and ASTEP observatories.Additionally, the $\textit{TESS}$ transits of TOI-1232 b exhibit strong transit timing variations (TTVs) with a super-period of $235.5 \pm 0.7$ days and a semi-amplitude of 27 minutes. Radial velocity (RV) follow-up with the FEROS spectrograph confirms the planetary nature of the transiting candidate, while a self-consistent $N$-body analysis of RVs and TTVs pinpoints the presence of a second outer Saturn-mass companion, TOI-1232 c with a period of $P_{c} = 30.356_{-0.012}^{+0.010}$ days. The TOI-1232 warm-giant system is particularly important due to the evidence of two massive planets that reside near the 2:1 commensurability but are not locked in a mean motion resonance (MMR). Thanks to $\textit{TESS}$, we have revealed a handful of these rare systems. Hence, TOI-1232 is an important addition to understanding the formation and dynamical evolution of such compact, massive, warm giant planets.
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All authors Deyan P. Mihaylov, Jan Eberhardt, Trifon Trifonov, Rafael Brahm, Thomas Henning, Andrés Jordán, Denitza Stoeva, Matías I. Jones, Lorena Acuña-Aguirre, Stefan Stefanov, M. Tala Pinto, Melissa J. Hobson, Nestor Espinoza, Felipe I. Rojas, Martin Schlecker, Vladimir Bozhilov, Tristan Guillot, Amaury H. M. J. Triaud, Jack J. Lissauer, Judith Korth, Hannu Parviainen, Laura Kreidberg, Philippe Bendjoya, Olga Suarez, Carl Ziegler, Pamela Rowden, Alexander Rudat, Veselin Kostov, Joshua N. Winn, Jon M. Jenkins, Karen A. Collins, Cristilyn N. Watkins, Don J. Radford, Chris Stockdale, Tianjun Gan

Cosmology and Nongalactic Astrophysics

A Non-parametric Method for the Inference of Halo Occupation Distributions

Jacob Kennedy, Eric Gawiser, Kartheik G. Iyer et al. (+1 more)

The galaxy-halo connection traces processes by which galaxies form and evolve. The halo occupation distribution (HOD) describes the relationship between galaxies and their host dark matter haloes. Measurements of the galaxy two-point correlation function (2PCF) allow us to extract information about the HODs of observed galaxy samples. Several parametric HOD models have been proposed in the literature, but the choice of parameterization restricts the space of possible HODs. To resolve this issue, we introduce a non-parametric HOD fitting method in which we train an emulator to learn the mappings among the galaxy 2PCF, physical properties used to select galaxy samples, and the HOD, all obtained from simulated past lightcones constructed with the Santa Cruz semi-analytic models. Implementing this emulator within a likelihood analysis framework, we derive constraints on the HOD of a galaxy sample when provided with a measurement of its 2PCF. Using the emulator to accelerate likelihood evaluations, we test the non-parametric HOD approach on a set of 2PCFs for mock galaxy samples drawn from the TNG100-1 simulation and selected above threshold values of stellar mass and star formation rate. Our framework is able to recover TNG100-1 HODs within 0.2 dex. We use the TNG100-1 mocks to tune the reported uncertainties to estimate those expected in the analysis of observations. Comparing to parametric HOD modeling routines applied to the same mock galaxy samples, our approach consistently infers the HOD with comparable or greater precision and accuracy.
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All authors Jacob Kennedy, Eric Gawiser, Kartheik G. Iyer, L.Y. Aaron Yung

Cosmology and Nongalactic Astrophysics

Lensing in the Blue III: Weak Lensing Shape Catalogs of 30 Merging Galaxy Clusters

Sayan Saha, Jacqueline E. McCleary, Spencer W. Everett et al. (+39 more)

We present the weak gravitational lensing dataset from the Super-pressure Balloon-Borne Imaging Telescope (SuperBIT), which imaged 30 galaxy clusters during its 45 night flight in April to May 2023. SuperBIT is a first-of-its-kind balloon-borne imaging telescope that achieved near diffraction-limited observations in near-space conditions above 98% of the Earth's atmosphere. We use the metacalibration algorithm to obtain calibrated galaxy shapes for our target clusters and several calibration fields, enabling unbiased reconstruction of the weak-lensing signal. We employ several diagnostics throughout the pipeline, including assessments of point-spread function (PSF) modeling residuals and their impact on weak-lensing measurements, as well as tests for correlations between galaxy shapes and measured galaxy and PSF properties. To assess the multiplicative shear bias of the pipeline, we analyze a parallel set of simulated images that incorporate the real observing conditions from the flight, including measured SuperBIT PSFs, observed sky backgrounds, and detector noise, yielding a bias of $(1.54 \pm 6.00)$ per cent.
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All authors Sayan Saha, Jacqueline E. McCleary, Spencer W. Everett, Maya Amit, Georgios N. Vassilakis, Emaad Paracha, Leo W.H. Fung, Steven J. Benton, William C. Jones, Gavin Leroy, Eric M. Huff, Richard Massey, Thuy Vy T. Luu, Ajay S. Gill, Mohamed M. Shaaban, Philippe Voyer, Adam Field, Anthony M. Brown, Giulia Cerini, Paul Clark, Matthew Craigie, Christopher J. Damaren, Tim Eifler, David Harvey, Eric Habjan, John W. Hartley, Bradley Holder, Mathilde Jauzac, David Lagattuta, Jason S.-Y. Leung, Lun Li, Johanna M. Nagy, C. Barth Netterfield, Susan F. Redmond, Jason D. Rhodes, Andrew Robertson, L. Javier Romualdez, Jurgen Schmoll, Ellen Sirks, Sut Ieng Tam, André Z. Vitorelli, Alfredo Zenteno

Wednesday 18 March

Solar and Stellar Astrophysics

The Effective Velocity of Transferred Mass: How Momentum Prescriptions Determine Binary Orbital Evolution

Jerry Li

In binary stellar evolution, the orbital response to mass transfer depends on how angular momentum is redistributed. We introduce a one-parameter family of prescriptions characterized by $\eta$, the fractional weight of the donor velocity in the effective velocity of the transferred mass: $v_{\rm trans} = \eta \, v_1 + (1-\eta) \, v_2$. We derive a closed-form expression for the angular momentum change per transfer event, $\Delta L/L = \delta m \, [(1-\eta)/M_2 - \eta/M_1]$. The two endpoint prescriptions ($\eta = 1$ and $\eta = 0$) produce angular momentum changes of opposite sign, yielding qualitatively different orbital evolution at every mass ratio. Conservative mass transfer ($\Delta L = 0$) corresponds uniquely to $\eta = M_1/M_{\rm tot}$, i.e. $v_{\rm trans} = v_{\rm COM}$. For constant $\eta$, we derive the general closed-form solution $a_f/a_0 = [(1-f)^{2(1-\eta)}(1+f q_0)^{2\eta}]^{-1}$.
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High Energy Astrophysical Phenomena

Degeneracy in Accretion Disk Spectra from Naked Singularities and Kerr Black Holes: Application to the AGN MCG-06-30-15

Vishva Patel, Sayantan Bhattacharya, Sudip Bhattacharyya et al. (+1 more)

Theoretical studies suggest that gravitational collapse can form either a black hole or a visible (naked) singularity. Identifying observational signatures that distinguish these two types of collapsed objects is a holy grail of physics. Here, we examine whether relativistic accretion disk spectra can provide such a test. We construct an additive table model for a thin accretion disk in the Joshi-Malafarina-Narayan (JMN-1) naked singularity geometry matched to a Schwarzschild exterior and fit it to NuSTAR X-ray data from the AGN MCG-06-30-15. Our results are compared with standard Kerr and Schwarzschild black hole models. We also include the relativistic reflection spectral component relxill. Despite their different underlying geometries, the spinning (Kerr) black hole and the non-spinning JMN-1 naked singularity provide similar spectral fits, which are significantly better fits than the Schwarzschild black hole. This degeneracy between the naked singularity and the Kerr black hole could lead to incorrect spin measurements of collapsed objects using disk spectra. The degeneracy could be broken with an independent spin measurement, which could also help identify a naked singularity. Our results could also have a role in different spin distributions of collapsed objects measured from gravitational-wave sources and X-ray binaries.
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All authors Vishva Patel, Sayantan Bhattacharya, Sudip Bhattacharyya, Pankaj S. Joshi

Astrophysics of Galaxies

Learning to See Sharper: A Physics-Informed Artificial Intelligence Framework for Super-Resolving Galaxy Spectra

Aryana Haghjoo, Shoubaneh Hemmati, Bahram Mobasher et al. (+5 more)

The information recoverable from galaxy spectra depends fundamentally on spectral resolution, yet assembling large samples at high resolution remains observationally expensive. We present a deep-learning framework for spectral super-resolution that enhances low-resolution galaxy spectra by a factor of $\sim$10 in resolving power ($R\sim100$ to $R\sim1000$). The model is trained on 2,858 paired JWST/NIRSpec observations from the JADES program, where low-resolution prism spectra are matched with medium-resolution grating spectra (G140M, G235M, G395M) combined into a unified reference covering $1.0-5.3\mu\mathrm{m}$. Our three-stage architecture performs an initial super-resolution, infers the redshift from the coarse reconstruction, and then applies a physics-informed residual refinement that uses attention across emission-line tokens to learn inter-line relationships and predict parametric line profiles, alongside a convolutional branch for continuum corrections. Evaluated on a 20% held-out sample, the model achieves noise-limited residuals over most of the spectral range and improves the signal-to-noise ratio of key diagnostic lines including [OII], H$\beta$, [OIII], and H$\alpha$. The super-resolved spectra separate features that are entirely unresolved at prism resolution, such as the [OIII] $\lambda\lambda4959,5007$ doublet and H$\beta$, in exchange for a modest retrieval of line fluxes. As a proof of concept using JWST data, this approach is readily extensible to the low-resolution grism spectroscopy that will be delivered by Euclid and the Roman Space Telescope, potentially enabling population-level diagnostics across millions of galaxy spectra that would otherwise be inaccessible at low-resolution.
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All authors Aryana Haghjoo, Shoubaneh Hemmati, Bahram Mobasher, Nima Chartab, Tim Eifler, Emily Ramey, Hooshang Nayyeri, Zahra Sattari

Earth and Planetary Astrophysics

Turbulence destroys thermal lobes around Mars-sized planetary embryos

R. O. Chametla, A. Moranchel-Basurto and F. J. Sánchez-Salcedo

The release of heat by a planetary embryo modifies the local density perturbations, forming thermal lobes in its vicinity, and thereby altering the torque exerted by the disk on the embryo. In laminar disks, these thermal torques can dominate the disk-embryo interaction, rendering the classical Lindblad and corotation torques largely subdominant. The aim of this work is to investigate how turbulence driven by the MRI instability affects the thermal lobes formed around a planetary embryo, and to analyze the resulting torque acting on the embryo. We evaluate the thermal torques exerted on a planetary embryo of mass $M_p=0.33M_{Mars}$ and on a planetary core with mass $M_{p}=1M_{\oplus}$, each embedded in a turbulent gaseous protoplanetary disk, by means of high-resolution 3D magnetohydrodynamics simulations that include thermal diffusion and an initially toroidal magnetic field. The magnetic field strength is characterized by the $\beta$-plasma parameter with $\beta\in\{50,1000\}$. We consider two values for the luminosity of the planetary embryo: $L=0$ (cold thermal lobes) and $L=L_c$ (hot thermal lobes), where $L_c$ represents the critical luminosity. We find that, even in the presence of a weak magnetic field and irrespective of the luminosity, for both planetary masses, the development of turbulence in the disk (which takes between 1.5 to 3 orbital periods) completely disrupts the thermal lobes. As a result, the torque acting on both the planetary embryo and the Earth-mass core displays a strongly oscillatory behavior. This suggests that planets with masses in the range $0.03M_{\oplus}\lesssim M_{p}\lesssim 1M_{\oplus}$ experience stochastic migration, as expected in turbulent disks. Thermal torques become inefficient in turbulent regions of protoplanetary disks, such as outside the dead zone, in both the inner and outer disk regions where the magnetorotational instability operates.
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Earth and Planetary Astrophysics

BOWIE-ALIGN: Exploring degeneracies in the muted transmission spectrum of the aligned hot Jupiter NGTS-2b with NIRSpec/G395H

Charlotte Fairman, Hannah R. Wakeford, Alastair B. Claringbold et al. (+15 more)

We present the first atmospheric observation and characterisation of the aligned, 1468 K hot Jupiter, NGTS-2b, with one JWST NIRSpec/G395H transit. These observations complete the GO 3838 observing campaign of the BOWIE-ALIGN program, which aims to investigate the link between hot Jupiter atmospheric composition and formation history through the atmospheric analysis of planets orbiting F stars that are aligned and misaligned with the host stellar spin axis. The 2.84-5.18 micron spectrum shows weak absorption features attributed to H$_2$O and CO$_2$ absorption, which our free chemistry retrievals fit with posteriors that converge on high mean molecular weight solutions attained through significant H$_2$O mixing ratios. By comparing our results to interior modelling, we show that some of these solutions exceed the 43.5x solar upper limit we obtained from our interior structure models. Such solutions are likely due to cloud-metallicity degeneracies and insufficient wavelength coverage to resolve them. We show that, in the case of our observations, the likelihood distribution of H$_2$O abundances is flat and uninformative, such that our retrievals are biased by the prior. Additionally, our statistically favoured atmospheric solution contains absorption from SO. The chemical abundances retrieved with this model are likely not astrophysically feasible and we demonstrate that the presence of SO is driven by only two data points. Our equilibrium chemistry retrievals hint at a subsolar C/O ratio and supersolar metallicity; however, we find wide posterior distributions that extend to solar values.
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All authors Charlotte Fairman, Hannah R. Wakeford, Alastair B. Claringbold, James Kirk, Eva-Maria Ahrer, Daniel Thorngren, Shang-Min Tsai, R. A. Booth, Anna B. T. Penzlin, Lili Alderson, Duncan A. Christie, M. López-Morales, N. J. Mayne, Annabella Meech, James E. Owen, Vatsal Panwar, Daniel Valentine, Peter J. Wheatley. Maria Zamyatina

Astrophysics of Galaxies

Contrasting evolutionary pathways of fast- and slow-rotating galaxies in the green valley

Shuang Zhou, Angela Iovino, Marcella Longhetti et al. (+2 more)

We investigate the evolutionary pathways of green valley (GV) galaxies drawn from the SDSS-IV/MaNGA survey. The GV sample is divided into fast- and slow-rotating galaxies based on stellar spin, and their stellar and gas-phase metallicities are compared. Fast-rotating galaxies exhibit systematically higher metallicities than slow-rotating galaxies in both gas and stars. However, the gas-phase difference is significant only at low stellar masses, while the stellar metallicity offset persists across the full mass range. Using a simple yet physically motivated chemical evolution model, optimised to jointly fit gas-phase metallicities and integrated stellar spectra, we reconstruct the star formation and chemical enrichment histories of individual galaxies and constrain gas inflow and outflow parameters. At low stellar masses, fast- and slow-rotating galaxies show similar gas-infall and star formation timescales, but the the slower population experienced stronger outflows which reduce their chemical content in both gas and stars. At high masses, the combination of reduced pristine gas inflow and more efficient gas removal in slow-rotating galaxies produce gas-phase metallicities comparable to fast-rotating galaxies but systematically lower stellar metallicities. These differences suggest distinct evolutionary pathways for GV galaxies. Slow-rotating galaxies likely experienced more mergers, usually associated with strong gas removal processes, leading to their systematically lower metallicities. At low masses, stronger supernova-driven outflows reduce their chemical content while leaving star-formation timescales similar to fast-rotating galaxies. At high masses, merger-triggered AGN feedback may rapidly deplete and suppress gas infall, producing the shorter star-formation timescales seen in slow-rotating galaxies. Alternative environmental and assembly-driven scenarios are also discussed.
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All authors Shuang Zhou, Angela Iovino, Marcella Longhetti, Francesco La Barbera, Luca Costantin

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Holographic Quantum Foam: Theoretical Underpinnings and Observational Evidence

Eric Steinbring and Y. Jack Ng

Spacetime is foamy due to quantum fluctuations. Various gedanken experiments show that distances fluctuate by amounts consistent with the holographic principle, hence the name "holographic quantum foam" (HQF). One important prediction of HQF is that necessarily there exists a dark sector in the universe. The resulting cosmology is found (at least qualitatively) to be consistent with observations. Interestingly the quanta of the dark sector are found not to obey the familiar (fermionic or bosonic) statistics, but the exotic statistics known as infinite statistics (or quantum Boltzmann statistics). The most important challenge now is to check if HQF is consistent with experiments/observations. One way is to look for observational evidence of blurred distant point-sources due to physics at the Planck scale. For over two decades it has been debated whether those tiny inherent uncertainties in time and path-length can accumulate in transiting electromagnetic wavefronts from quasars and Gamma-Ray Bursts (GRBs). But a recent event is special: GRB221009A was extremely bright and energetic. That allowed follow-up across the whole spectrum from the optical/near-infrared through to X-rays, and including the highest-ever-recorded energy gamma-rays; all consistent with blurring by HQF. Those data, and a calculation of the HQF-widened point-spread function (PSF) for real telescopes viewing a GRB are presented.
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Astrophysics of Galaxies

The Galactic distribution of planetary nebulae with different types of dust

Diego Hernández-Juárez, Mónica Rodríguez and Miriam Peña

We identify different dust features in our compilation of infrared spectra for 267 planetary nebulae (PNe) from the Spitzer, ISO, and IRAS telescopes. We classify 209 objects according to their dust type: mixed dust (MD), oxygen-rich dust (ORD), carbon-rich dust (CRD), PNe with only polycyclic aromatic hydrocarbons (PAHs) in their spectra (oPAH), and featureless (F) PNe. We study statistically the distributions of surface brightness and diameter of PNe with different types of dust as well as their distributions in the Galaxy.We find that both MD and ORD PNe are closer to the Galactic centre than CRD and oPAH PNe, and that the Galactic distributions of each pair of groups are statistically compatible, suggesting that they have similar progenitors. Since oPAH PNe have, on average, larger diameters and lower surface brightness than CRD PNe, we suggest that oPAH PNe are evolved CRD PNe. On the other hand, F PNe have the lowest surface brightness and the largest diameters, suggesting they could contain evolved PNe from any initial type of dust. Among the PNe with silicates, we find that only a few ORD PNe have just amorphous silicates in their spectra, and their distributions of Galactocentric distances and Galactic heights suggest that they had low-mass progenitors. MD PNe with both amorphous and crystalline silicates have the largest surface brightness and the smallest diameters and might be the earliest stages of PNe with the most massive and metal-rich progenitors.
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Instrumentation and Methods for Astrophysics

ALABI: Active Learning for Accelerated Bayesian Inference

Jessica Birky and Rory K. Barnes

We present Active Learning for Accelerated Bayesian Inference (alabi): an open-source Python package for performing Bayesian inference with computationally expensive models. Given a forward model and observational data to construct a likelihood and priors, alabi\ uses a Gaussian Process (GP) surrogate model trained to predict posterior probability as a function of input parameters, and employs active learning to iteratively improve GP predictive performance in high-likelihood regions where the GP is most uncertain. alabi\ provides a uniform interface for using Markov chain Monte Carlo (MCMC) with different packages, including the affine-invariant sampler emcee, and nested samplers dynesty, multinest, and ultranest. This approach facilitates accurate estimation of the desired posterior distribution, while reducing the number of computationally expensive model evaluations required by factors of thousands. We demonstrate the performance of alabi\ on a variety of test cases, including where inference is challenging due to complex posterior structure or high dimensionality. We show that alabi\ offers a substantial improvement for likelihood functions with evaluation times $\gtrsim 1$\,s, speeding up MCMC computations by a factor of $10-1000\times$ when tested on problems with up to 64 dimensions.
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Astrophysics of Galaxies

Known changing-look AGN located within Rubin Deep Drilling Fields

Mariangella Camus and Swayamtrupta Panda

Changing-look active galactic nuclei (CL-AGN) exhibit spectroscopic and photometric changes on timescales of months to years, making them powerful laboratories for studying accretion variability onto supermassive black holes. Motivated by the growing relevance of large spectro-photometric time-domain surveys, especially the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), we compiled a master catalog of known CL-AGN from the literature and evaluated its spatial overlap with the Rubin survey footprint. Using a geometric cross-match based on sky coordinates, we identify 79 sources located in high-cadence regions of the main survey footprint (Wide-Fast-Deep, or WFD), including 5 particularly favorable targets lying within the Deep Drilling Fields (DDFs) of COSMOS and XMM-LSS. These sources represent especially promising candidates for future variability studies in the Rubin era. This Research Note presents a first proof of concept for connecting known CL-AGN with Rubin observing fields, while the full catalog and a more comprehensive analysis will be presented in a forthcoming paper.
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Earth and Planetary Astrophysics

Gamma Ray Bursts Effects on Extinction and Survivability in the Galaxy

Matan Sade, Aviv Tsarfati and Ofek Birnholtz

High-energy astrophysical events, particularly Gamma Ray Bursts (GRBs), have been proposed as significant contributors to mass extinction events on Earth-like planets in most of the galaxy, internal to our radius in it. This paper examines the extent to which GRBs may reset the evolutionary progress of complex life through repeated extinction-level disruptions. While resilient extremophiles may survive even the most intense GRBs, more complex surface-dwelling organisms are vulnerable to indirect atmospheric effects, primarily UV exposure following ozone depletion. By identifying evolutionary milestones and estimating how frequently GRBs would need to occur to prevent recovery between such milestones, this work proposes that GRBs could act as evolutionary filters, limiting the emergence of advanced life, but only much closer to the galactic center. We consider the implications for searches of various biosignatures versus technosignatures.
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