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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 22 September

Instrumentation and Methods for Astrophysics

Laboratory Evidence that Methanol-Rich Ice Mantles Lower Methyl Formate Binding Energies

Rachel E. Gross, Jeroen Terwisscha van Scheltinga, L. Ilsedore Cleeves et al. (+5 more)

Complex organic molecules are widely detected in star-forming regions and are important precursors to prebiotic species. Because these molecules are thought to form primarily within icy grain mantles, their desorption is assumed to be regulated by the sublimation of the surrounding H$_2$O ice matrix. However, observations increasingly reveal gas-phase abundances of methyl formate (MF) at temperatures well below the sublimation temperature of water ice (T ~ 100K), challenging this view. To investigate how ice composition and phase influence MF desorption, we present laboratory temperature-programmed desorption measurements of MF from four astrophysically relevant substrates: amorphous and crystalline H$_2$O and CH$_3$OH. Desorption kinetics were analyzed using pre-exponential factors derived from transition-state theory with leading-edge analysis and non-negative least-squares inversion to recover binding-energy distributions. We find that MF binds more weakly to CH$_3$OH ice than to H$_2$O-rich substrates, with representative binding energies of ~6247K for amorphous H$_2$O, ~6213K for crystalline H$_2$O, and ~5469K for amorphous CH$_3$OH. MF deposited on crystalline CH$_3$OH exhibits coverage-independent leading edges consistent with multilayer or island desorption, yielding an effective binding energy of 5333K. Enhanced surface mobility and reduced trapping efficiency on methanol ice, combined with weaker MF binding, provide a natural explanation for the early appearance of gas-phase MF observed in star-forming environments, with characteristic desorption temperatures of ~85K on CH$_3$OH and ~95-100K on H$_2$O. Together, these effects support a two-step thermal desorption pathway in which MF associated with CH$_3$OH-rich ice can be released prior to bulk H$_2$O sublimation.
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All authors Rachel E. Gross, Jeroen Terwisscha van Scheltinga, L. Ilsedore Cleeves, Catherine A. Dukes, Robin T. Garrod, Alexia Simon, Shane Sawyer, Adam Woodson

Solar and Stellar Astrophysics

Light-curve analysis of the classical nova YZ Ret: revisit with fully self-consistent nova outburst models

Izumi Hachisu and Mariko Kato

YZ Ret is a well observed nova from the first detection of an X-ray flash phase in classical novae until the end of a supersoft X-ray source phase. We have reanalyzed multiwavelength light curves of YZ Ret over the total duration of the outburst. Our fully self-consistent nova outburst model, a 1.25 $M_\odot$ white dwarf (WD) and a mass accretion rate of $1\times 10^{-9} ~M_\odot$ yr$^{-1}$ on to the WD, reasonably reproduced $V$/$g$ light curves as well as the very early X-ray flash and late supersoft X-ray light curves. This model explains the emergence epoch of the GeV gamma-ray emission because a shock naturally arises far outside the nova (WD) photosphere just after the optical maximum. In our model, before optical maximum, later ejected matter has a smaller velocity than that of earlier ejecta and therefore the ejecta expands while, after optical maximum, later ejected matter has a larger velocity than that of earlier ejecta and collision with the earlier ejecta makes a shock.
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Astrophysics of Galaxies

From starlight to dark matter: a stochastic interpolation approach to map dark matter from stellar density

Xiaowei Ou, Lina Necib, Carolina Cuesta-Lazaro et al. (+9 more)

The dark matter halo profile in galaxies holds key information about the nature of dark matter and galaxy formation. Constraining the dark matter profile of galaxies beyond the Milky Way traditionally requires expensive spectroscopic observations for kinematic information. In this paper, we explore a conditional generative model framework to map the dark matter profile of Milky Way-mass galaxies from stellar density profiles, more easily obtainable through large photometric imaging surveys. As a proof of concept, we train the model to learn a stochastic bridge between instrument systematics-free baryonic stellar distributions and underlying dark matter density maps from the DREAMS hydrodynamics simulation suite. We recover 2D dark matter density profiles with a typical accuracy of $\sim0.1$ dex ($\sim1.5$% of the truth in log scale). The stochastic sampling procedure provides uncertainty estimates of the predicted dark matter map, with typical values $\sim0.1$ dex. Out-of-domain tests with Milky Way-mass galaxies from IllustrisTNG and FIRE simulations show that, while the model can qualitatively be generalized to TNG50 galaxies from IllustrisTNG, the model is sensitive to the galaxy formation model, with $\sim0.2$-$0.4$ dex over-prediction for the inner profiles ($r\lesssim5$ kpc) of the FIRE test galaxies. Future work will explore training with additional suites of simulations and/or conditioning on additional information, such as multi-band images. Our results are a first step towards using generative models as a flexible, uncertainty-aware framework for turning forthcoming data from large imaging surveys into spatially resolved dark matter maps.
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All authors Xiaowei Ou, Lina Necib, Carolina Cuesta-Lazaro, Paul Torrey, Niusha Ahvazi, Alyson M. Brooks, Berthy T. Feng, Alex M. Garcia, Jiaxuan Li, Jonah C. Rose, Xuejian Shen, Mark Vogelsberger

Earth and Planetary Astrophysics

Revisiting planetesimal formation from mm-sized grains in pressure bumps

Tabassum S Tanvir, Jacob B Simon, Daniel Carrera et al. (+1 more)

We present evidence that the streaming instability (SI) can form planetesimals from millimeter grains inside axisymmetric pressure bumps, provided the bump is not too strongly reinforced. We conducted three-dimensional local shearing-box simulations of millimeter grains in a Gaussian pressure bump of amplitude $A = 0.6$, at a resolution of $160/H$. We varied only the Newtonian reinforcement timescale $t_{\rm reinf}$, the timescale on which the imposed bump is restored against particle back-reaction. Our reference run T1 uses $t_{\rm reinf} = 1\,\Omega^{-1}$. Particles pile up in a narrow axisymmetric band at the minimum-headwind point, cross the Roche density, and collapse through direct gravitational instability (GI). In our weakly reinforced run T100 with $t_{\rm reinf} = 100\,\Omega^{-1}$, the outcome is different. Particles drift through the bump roughly three times more slowly, and dense SI-like filaments develop across a wide radial region well before the Roche density is reached. These results are consistent with a residence-time criterion, which states that for the SI to grow, $t_{\rm cross} > t_{\rm grow}$, where $t_{\rm cross}$ is the time a particle spends inside the region where the ratio $Z/\Pi$ of the solid abundance $Z = \Sigma_p/\Sigma_g$ to the headwind parameter $\Pi = \Delta v/c_{\rm s}$ is high enough for strong clumping, and $t_{\rm grow}$ is the SI growth time. T1 violates this criterion, and T100 satisfies it. Our results suggest that the reinforcement timescale matters for millimeter grains because it helps set the crossing time, and therefore whether the SI has time to grow. We caution, however, that our reinforcement scheme is an idealised numerical construction rather than a physical bump-forming mechanism such as a planet, and a more definitive test of this picture will require simulations with a more physically motivated bump.
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All authors Tabassum S Tanvir, Jacob B Simon, Daniel Carrera, Jeonghoon Lim

Earth and Planetary Astrophysics

M Dwarf Singles and Multis Have Dissimilar Metallicities Indicating Different Origins

Aida Behmard, Sheila Sagear, Yuxi Lu et al. (+3 more)

It is unclear if host star metallicities differ between systems with one detected transiting planet ("singles") or multiple detected transiting planets ("multis") around FGK dwarfs. Here, we find strong evidence that they do for M dwarfs. We use a homogeneous sample of FGK and M dwarf chemical abundances to demonstrate that M dwarf multis are significantly more metal-poor than singles ($p$ = 0.00079), even when we only consider small (<4 $R_{\oplus}$) planets ($p$ = 0.0013). This result emerges at the late-K to M dwarf transition. We observe that M dwarf multis become more metal-poor as a function of increasing planet multiplicity. Additionally, planets in singles have significantly higher eccentricities and shorter orbital periods compared to planets in multis. We interpret these findings as evidence that M dwarf singles lead relatively active dynamical lives, and the different planetary architectures of singles and multis arise from distinct dynamics influenced by metallicity. This may not occur in FGK systems because their more massive protoplanetary disks may supply enough planet-forming material to instigate dynamics that lead to only one transiting planet, even when the host star metallicity is low. Another possibility is that multis are less compact around FGK dwarfs because they form from larger disks, which may often cause them to be observed as singles in transit data.
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All authors Aida Behmard, Sheila Sagear, Yuxi Lu, Romy Rodríguez Martínez, Adrian M. Price-Whelan, Soichiro Hattori

Astrophysics of Galaxies

The lifetimes and properties of Little Red Dots in the AMBRA simulation

Patrick LaChance, Yihao Zhou, Aklant Kumar Bhowmick et al. (+6 more)

We identify and analyze the little red dots (LRDs) in the AMBRA cosmological hydrodynamic simulation, by producing mock observations of the galaxies and active galactic nuclei (AGN) between redshifts 5 and 8. We produce these mock observations with both a standard AGN emission model, and a “gas-enshrouded” model, and find that the presence of a gas-enshrouded AGN is instrumental to the reproduction of dim LRDs (F444W magnitude $>$ 26.0). We find a steeper decrease in LRD density between $z=5$ and $z=8$ within AMBRA than seen in observations, resulting in a relative underproduction of LRDs beyond $z\sim6$ in AMBRA. With the addition of unresolved AGN variability, the decline with redshift flattens, and the LRD redshift evolution in AMBRA becomes broadly consistent with other theoretical datasets, and closer to that seen in observations. We find that the LRDs in AMBRA are pre-existing black hole–galaxy systems that are undergoing an LRD phase, selected primarily by the brightness of the AGN relative to its host. While the exact duration of these LRD phases is not possible to determine due to the unresolved nature of the AGN environment, we use the available time-series data to place limits on the lifetimes of the LRDs in AMBRA. We find that the vast majority of LRDs in AMBRA have lifetimes between $\sim3$ and $\sim 300$ Myr with LRD lifetime increasing with both black hole and host galaxy mass. The lower mass LRDs are more dependent on housing a gas-enshrouded AGN, and have shorter lifetimes ($\rm \sim30~Myr$). The higher mass LRDs are less sensitive to their AGN environment, but require more compact host galaxies, and have longer lifetimes ($\rm \sim100~Myr$).
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All authors Patrick LaChance, Yihao Zhou, Aklant Kumar Bhowmick, Rupert A.C. Croft, Tiziana Di Matteo, Laura Blecha, Fabio Pacucci, Paul Torrey, Simeon Bird

Astrophysics of Galaxies

N/O-enhanced chemical enrichment by massive stars: the interplay of optically-thick winds and rotation

Boyuan Liu, Michela Mapelli, Lumen Boco et al. (+1 more)

Recent JWST observations have revealed a sample of high-$z$ galaxies with highly enhanced N/O abundance ratios, $\log\rm (N/O)\gtrsim -1.1$. Strong optically-thick winds of rotating massive stars going through the Wolf-Rayet (WR) phase provide a viable explanation for such N/O enhancements, supported by the direct spectroscopic WR signatures discovered in a few galaxies. Such strong winds are also needed to reproduce the single WR stars in the Small Magellanic Cloud (SMC). Here, we compute the metal yields of massive ($\sim 20-100\ \rm M_\odot$), metal-poor stars using two sets of MESA single stellar evolution models with and without optically-thick winds in a dense grid of metallicities ($Z_\star\sim 0.001-0.0045$) and initial spins ($\omega\equiv\Omega/\Omega_{\rm crit}\sim 0-0.7$). Considering an initial spin distribution based on observations of O-type stars in the SMC, we find that both sets produce strong N/O enhancements up to $\rm \log(N/O)\sim 0.1$ within a few Myr after a starburst. The models with optically-thick winds undergo a rapid transition from high N/O to the `normal' state of $\rm \log(N/O)\sim -1.5$ at $t\sim 3-4$ Myr driven by C/O-rich winds, while the transition is slower and weaker without optically-thick winds. The optically-thick-wind scenario can reproduce the nebular C, N, O, and He abundance patterns of three representative high-$z$ galaxies showing direct WR signatures: RXCJ2248-ID, Sunburst Arc, and MARTA 4327, with stellar metallicities and ages similar to those inferred from SED-fitting. This can be interpreted as a coherent evolution sequence captured before ($t\lesssim 3$ Myr), during ($t\sim 3-4$ Myr), and after ($t\gtrsim 5$ Myr) the transition. In contrast, the optically-thin-wind-only scenario ejects much less C and O via winds and cannot reproduce Sunburst Arc and MARTA 4327. The yields are available at https://zenodo.org/records/22897057.
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All authors Boyuan Liu, Michela Mapelli, Lumen Boco, Xihan Ji

Astrophysics of Galaxies

The birth and fate of stellar clumps in super-early galaxies

B. Das, A. Ferrara, A. Pallottini et al. (+2 more)

(Abridged) JWST has revealed extremely compact stellar clumps in galaxies at z>6, but their formation mechanism and subsequent evolution remain uncertain. We investigate whether such systems can form in-situ through the fragmentation of an early galactic disk and how stellar feedback regulates their properties. We perform a suite of radiation-hydrodynamical simulations of an isolated galaxy ("Ninfea_blu"), with $\rm M_{vir}=1.5\times10^{10} M_\odot$, evolved for 100 Myr from z=16 to 12.5 with a maximum spatial resolution of 3.6 pc. In all cases, the gas rapidly forms a rotationally supported disk, reaches a peak star formation rate of $10-15\rm M_\odot yr^{-1}$, and fragments into dense stellar clumps. Toomre-unstable regions ($Q_{\rm gas}<1$) appear before the onset of star formation, and the first stellar structures form preferentially within these regions, supporting a Toomre-like gravitational fragmentation pathway.The clumps have stellar masses of $10^6-2\times10^8\,M_\odot$, effective radii of 7-50 pc, and surface densities of $0.2-3\times10^4\rm M_\odot pc^{-2}$, overlapping much of the parameter space occupied by observed z>6 clumps. Feedback reduces the cumulative stellar mass by 30-40%, lowers the gas mass retained within clumps by ~1 dex, and suppresses their high-mass tail without preventing their initial formation. Clumps subsequently migrate, interact, undergo tidal stripping, and disperse. The clump mass function produces a power law slope of -1.88, which aligns closely with observations. Moreover, their contributions to the stellar mass and intrinsic UV luminosity decline from 0.41 and 0.40 at 20 Myr to 0.13 and 0.10 at 100 Myr, respectively. We conclude that fragmentation of compact, gas-rich disks provides a viable origin for many of the dense stellar systems observed in the early Universe, while feedback and internal dynamics primarily regulate their growth and fate.
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All authors B. Das, A. Ferrara, A. Pallottini, E. Ntormousi, M. Kohandel

Astrophysics of Galaxies

Cavity-driven Gas Transport in Cool-Core Clusters: Implications for Multiphase Gas Cooling

Prathamesh Tamhane, Brian McNamara and Paul Nulsen

We present a study of gas uplift by cavities and its role in promoting the formation of molecular gas in cool-core galaxy clusters. Using a sample of 24 clusters, we quantify the parameter space of gas uplift, including lifting masses, velocities, radii, and cooling times, and compare the displaced hot gas to observed molecular gas masses. Almost all clusters contain sufficient low-entropy gas within the central $\sim$10 kpc to account for the observed molecular gas. The molecular gas mass scales approximately linearly with the maximum gas mass displaced by cavities. Gas with cooling times of a few $10^8$ yr can be transported to typical H$\alpha$ filament radii of 10–30 kpc at characteristic velocities of 150–400 km s$^{-1}$, whereas gas with $t_{\rm cool}\sim10^9$ yr generally requires uplift to $\gtrsim60$ kpc. The mass expected to cool over the lifetimes of the currently observed cavities is comparable to the molecular reservoir in several systems, assuming that 50% of the displaced gas mass is lifted and cools, whereas other systems contain excess molecular gas. This suggests that the molecular gas reservoirs may have accumulated over multiple AGN feedback cycles involving repeated gas uplift and cooling, or through additional processes. H$\alpha$ and infrared luminosities increase linearly with X-ray cooling luminosity, linking the multiphase emission to the cooling atmosphere. Overall, our results support a picture in which repeated AGN outbursts with gas uplift promote the condensation of low-entropy gas and help build molecular reservoirs in cool-core BCGs.
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Instrumentation and Methods for Astrophysics

The Simons Observatory: Commissioning of the Mid-Frequency Small Aperture Telescopes

Kathleen Harrington, Remington Gerras, Nicholas Galitzki et al. (+88 more)

The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO Small Aperture Telescopes (SATs) will cover six spectral bands between 30 and 280 GHz primarily to search for evidence of primordial gravitational waves in the large angular scale $B$-modes of the CMB polarization. The first two Mid-Frequency (MF) SATs, operating in the 90 and 150 GHz frequency bands, began commissioning observations in late 2023, and we present the results of those observations here. Each MF SAT operates with approximately 9,400 biased transition-edge sensors (TES) at 1 mm of precipitable water vapor (PWV), representing a typical 80% yield. Planet observations confirm the telescope optics performance, calibrate the instrument response, and measure the end-to-end optical efficiency of the SATs. The realized instrument efficiencies are within the range expected based on instrument model predictions. In nominal observing conditions, the noise equivalent temperatures from both telescopes combined are $2.4~\mathrm{\mu K_{CMB}\sqrt{s}}$ at 90 GHz and $3.2~\mathrm{\mu K_{CMB}\sqrt{s}}$ at 150 GHz, substantially outperforming the baseline instantaneous sensitivity targets for the observatory.
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All authors Kathleen Harrington, Remington Gerras, Nicholas Galitzki, Samuel Day-Weiss, Yoshinori Sueno, Thomas Alford, Michael J. Randall, Kyohei Yamada, Maximiliano Silva-Feaver, Kevin Crowley, Shunsuke Adachi, Alexandre E. Adler, Prakamya Agrawal, Simone Aiola, David Alonso, Kam Arnold, Susanna Azzoni, Andrew Bazarko, Sanah Bhimani, Simon Biquard, Bryce Bixler, Josh Borrow, Michael L. Brown, Erminia Calabrese, Yuji Chinone, Steve K. Choi, Nadia Dachlythra, Mark Devlin, Simon Dicker, Peter N. Dow, Shannon M. Duff, Jo Dunkley, Rolando Dunner, Daniel Dutcher, Hamza El Bouhargani, Josquin Errard, Allen Foster, Ken Ganga, John Groh, Yilun Guan, Jon E. Gudmundsson, Saianeesh Haridas, Masaya Hasegawa, Matthew Hasselfield, Shawn W. Henderson, Carlos Hervías-Caimapo, Adam D. Hincks, Renée Hložek, Johannes Hubmayr, Bradley R. Johnson, Yutaro Kasai, Brian Keating, Ben Keller, Theodore Kisner, Brian J. Koopman, Akito Kusaka, Adrian Lee, JB Lloyd, Anto Lonappan, Marius Lungu, Aashrita Mangu, Michael McCrackan, Jeff McMahon, Jenna Moore, Thomas W. Morris, Hironobu Nakata, Federico Nati, Laura Newburgh, David V. Nguyen, John Orlowski-Scherer, Lyman Page, Ioannis Paraskevakos, Tristan Pinsonneault-Marotte, Erik Rosenberg, Yuki Sakurai, Goureesankar Sathyanathan, Thomas P. Satterthwaite, Yudai Seino, Elle Shaw, Sara M. Simon, Suzanne T. Staggs, Junna Sugiyama, Junya Suzuki, Satoru Takakura, Osamu Tajima, Alex Thomas, Daniel B. Thomas, Tran Tsan, Eve Vavagiakis, Yuhan Wang, John Wilson

High Energy Astrophysical Phenomena

SN2025aico: An Interesting Case Of $^{56}$Ni Mixing, Ejecta Asymmetries, and Dust Formation in a Type IIb Supernova

Grace Davis, Kyle Medler, Chris Ashall et al. (+8 more)

Stripped-envelope supernovae provide a window into how massive stars lose their layers, mix radioactive material, produce dust, and explode asymmetrically. We present optical, near-infrared (NIR), and mid-infrared (MIR) observations of SN~2025aico, a Type~IIb supernova in LEDA~35384. Our spectroscopic sequence, spanning $+1$ to $+167$ d after explosion, follows its evolution from a photospheric phase exhibiting both hydrogen and helium features to prominent helium emission and, ultimately, nebular-phase ejecta. Using He I $1.083$ and $2.0581\,\mu$m transitions, we investigated the kinematics and geometry of the helium-rich material. Both transitions exhibit a three-phase, non-monotonic velocity evolution: an initial rapid decline, a subsequent increase, and an eventual plateau. We interpret this behavior as evidence for limited outward mixing of $^{56}$Ni, such that radioactive energy deposition reaches the outer helium-rich ejecta progressively as the ejecta expand, producing the non-thermal electrons responsible for helium excitation. After $\sim100$ d, both NIR He I transitions develop double-peaked emission profiles. Similar structure in the oxygen emission indicates ejecta asymmetry. Comparison with other supernovae suggests a tentative connection between this structure and explosion energy, potentially linked to the delay between core collapse and explosion. Serendipitous JWST observations at $+124.4$d reveal an infrared excess. Modeling favors warm ($\sim800$–$1500$K) carbon dust newly formed in the ejecta, together with cooler carbon or silicate dust likely associated with pre-existing circumstellar material. SN~2025aico demonstrates how continuous optical-to-MIR observations can connect progenitor evolution, explosion physics, ejecta geometry, and dust production.
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All authors Grace Davis, Kyle Medler, Chris Ashall, Willem B. Hoogendam, Cameron Pfeffer, David O. Jones, Shunsaku Horiuchi, Tyco Mera, Benjamin Shappee, Charlotte Ward, Grace Showerman

Astrophysics of Galaxies

Radio Quasars in the Cosmic Dawn: A Spectroscopic Sample from the DESI Survey

Anniek J. Gloudemans, Jinyi Yang, David M. Alexander et al. (+55 more)

We present the largest statistical spectroscopic sample of radio quasars at 4.7<z<6.7 to date. These have been selected from a dedicated Dark Energy Survey Instrument (DESI) target program and provide a robust sample to study the influence of radio jets on early quasar evolution. Using low-frequency radio data from the LOFAR Two Metre Sky Survey Data Release 3 (LoTSS-DR3) at 144 MHz, we identify 83 high-z radio quasars, 26 of which are classified as radio-loud (5-15% of 646 confirmed high-z quasars, defined as $R = F_{5\text{GHz}}/F_{4400A} >10$). With radio luminosities of $\sim10^{25-28}$ W/Hz, the radio emission in all 83 quasars is expected to be jet-dominated rather than powered by star formation. Analysis of their rest-frame ultra-violet (UV) spectra reveals broadly similar composite spectral properties and CIV velocity shifts compared to radio non-detected quasars. The radio-detected and radio-loud quasars exhibit slightly smaller Ly$\alpha$ and CIV equivalent widths on average, however, we find no significant evidence ($\sim1.3\sigma$) for a higher fraction of weak-line quasars (WLQs; ~10+/-4% versus ~4+/-1% for radio non-detected quasars). We further find that the broad absorption line (BAL) quasars are predominantly radio-quiet, and no correlation is observed between absorption index and radio-loudness, suggesting that radio emission is not produced by the BAL outflows themselves and are physically distinct phenomena. Our results demonstrate that powerful radio jets were already well-established by z~5.
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All authors Anniek J. Gloudemans, Jinyi Yang, David M. Alexander, Arjun Dey, Xiaohui Fan, Victoria A. Fawcett, Martin J. Hardcastle, Stephanie Juneau, George K. Miley, Leah K. Morabito, Adam D. Myers, Swayamtrupta Panda, Huub J. A. Röttgering, Timothy Shimwell, Daniel J. B. Smith, Feige Wang, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, P. Doel, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, C. Hahn, M. Ishak, R. Joyce, R. Kehoe, D. Kirkby, T. Kisner, A. Kremin, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, F. Prada, I. Pérez-Ràfols, A. Robertson, G. Rossi, E. Sanchez, E. F. Schlafly, D. Schlegel, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, R. Zhou, H. Zou

Earth and Planetary Astrophysics

Simulated Effects of Radioactive Elements on Magnetic Evolution and Atmospheric Mass Loss of Earth-like Planets

Nathaniel Tanglin and Juliette Becker

Thousands of exoplanets have been discovered in recent decades, yet Earth remains the only known world with life. To assess the potential habitability of other planets, we must identify the importance of various physical conditions that may contribute to sustaining life. One such factor is the presence of a planetary magnetic field. A planet's magnetic field can protect its atmosphere from photoevaporation, and its long-term strength depends on interior heat flow driven by radiogenic heating from isotopes such as 40K, 232Th, 235U, and 238U. In this work, we use the VPLanet code to simulate the coupled thermal, magnetic, and atmospheric evolution of Earth-like planets with varying radiogenic heat budgets orbiting G-, K-, and M-dwarf stars. The range of isotope abundances tested is based on observed stellar elemental distributions for planet-hosting stars in the Milky Way. We find that variations in radiogenic heating slightly extend dynamo lifetimes and reduces atmosphere and surface water loss for K- and G-dwarf systems, while its effects are more negligible for M dwarfs. Our results show that, while stellar irradiation and planetary location primarily control photoevaporation rates, radiogenic heating contributes to planetary habitability in a small subset of cases and may help refine target selection for future surveys.
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High Energy Astrophysical Phenomena

Waiting in the wings: extended emission GRBs from high latitude emission and jet expansion

Isabelle Worssam, Benjamin P. Gompertz and Hendrik J. van Eerten

The process powering extended emission (EE) Gamma Ray-Bursts (GRBs) from compact object mergers is a debated problem due to their observed prompt emission timescales of 10 to 100s, far in excess of the expected accretion timescales following a binary neutron star (BNS) merger. Here, we present an analytical thin shell structured jet model designed to alleviate this tension. We show that a changing jet structure in which early emission is produced by a high Lorentz factor narrow, structured jet and later emission comes from a wider, lower Lorentz factor tophat-like jet can successfully reproduce the EE GRB phenomenology. All emitting shells are powered by a $0.1$ $M_{\odot}$ accretion torus and launched within a time window of 2s after merger. Spatially-resolved opacity checks confirm that our emission sites remain optically thin, in part due to the spectral softness associated with EE. We present light curves from our model compared to representative EE bursts detected by Swift: GRBs 211211A, 211227A and 060614. While our light curves provide good matches to the data, our spectra do not evolve fast enough when compared to the well-measured spectral evolution observed in GRB 211211A. We discuss an update to the model incorporating inherent spectral evolution in the shells as future work. We also show a parameter exploration of the model and identify a parameter range within which standard short GRB-like light curves could be produced, showcasing the ability of the model to produce short bursts with and without EE.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Supernova Gamma-Ray Echo as an Astrophysical Near Detector for Galactic Neutrino Propagation

Garv Chauhan and Yago Porto

Core-collapse supernova neutrinos offer a unique probe of physics beyond the Standard Model over Galactic baselines. Yet even a high-statistics nearby burst may be limited by source uncertainties, especially for propagation effects that average over energy and appear only as an overall flux suppression. Inspired by near–far comparisons in terrestrial oscillation experiments, we show that next-generation MeV observations of the supernova gamma-ray echo—the delayed 511 keV signal induced by the neutrino burst in the stellar envelope—can serve as an astrophysical near detector for the emitted $\bar\nu_e$ fluence. Comparing this echo-inferred source fluence with the surviving flux measured at Earth gives a direct test of neutrino propagation between the stellar surface and the detector. For pseudo-Dirac neutrinos, this turns the fully averaged active–sterile oscillation regime from an unobservable source-normalization ambiguity into a measurable near–far deficit, with sensitivity for nearby progenitors to splittings $\delta m^2\gtrsim 10^{-18}~{\rm eV}^2(0.22~{\rm kpc}/D)(E_\star/15~{\rm MeV})$. The same near–far logic also applies to other propagation-induced modifications of the observed flux, including neutrino decay and neutrino interactions with Galactic dark matter.
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Instrumentation and Methods for Astrophysics

Interference Meets Inference: Bayesian Time-Series Modeling of Radio-Frequency Interference

Jade M. Ducharme, Andrei Li, Michael J. Wilensky et al. (+1 more)

Radio-frequency interference (RFI) remains a major challenge for modern radio astronomy experiments. In this work, we cast RFI detection as a one-dimensional time-series anomaly-detection problem and develop a probabilistic mixture-model framework for separating a smoothly varying astronomical background from anomalous contamination. The model jointly describes the clean and contaminated components and assigns each time sample a posterior probability of belonging to the RFI state, rather than relying solely on binary flags. This probabilistic formulation provides a measure of classification confidence, enables uncertainty propagation into derived downstream statistics, and offers additional information for investigating ambiguous events. We apply the framework to observations from the Murchison Widefield Array collected in 2014, producing "soft" classification labels and seasonal RFI trends. We perform a parallel analysis using the Sky-Subtracted Incoherent Noise Spectrum software pipeline (SSINS), which produces "hard" classification labels. Overall, the mixture model provides similar and in some cases superior classification results while providing a complementary probabilistic description of RFI contamination and its uncertainty.
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All authors Jade M. Ducharme, Andrei Li, Michael J. Wilensky, Adrian Liu

High Energy Astrophysical Phenomena

A Coherent Search for New Galactic Magnetars using Fermi/GBM and follow-up Swift/BAT: 7 Candidates and a Large Burst Catalog

Ariel Perera, Barak Zackay and Tejaswi Venumadhav

Galactic magnetars are a rare class of neutron stars with extreme magnetic fields, with only about 30 known sources. Their short hard X-ray and soft gamma-ray bursts provide an important channel for discovering magnetar activity. Wide-field instruments such as the Fermi Gamma-ray Burst Monitor (GBM) are well suited to detecting these bursts, but their broad localization uncertainties make it difficult to associate individual bursts with specific sources. Coded-aperture telescopes, in contrast, provide arcminute-scale localizations but have narrower fields of view. We search for previously unidentified magnetars and construct a magnetar burst catalog by combining a broad sample of short, soft triggers from our coherent GBM detection pipeline over 2013-2025 with targeted searches of archival Swift/BAT images. We develop a statistical association framework that uses BAT detections to localize GBM bursts to arcminute precision, together with a spatio-temporal clustering framework that associates poorly localized bursts with common sources. Together, these methods identify 1720 magnetar bursts, of which 1170 are confidently associated with 11 known magnetars. The remaining 550 bursts could not be assigned to specific sources. We identify seven candidate new magnetars through three complementary discovery channels. The catalog, composed of the associated bursts, extends to the lowest fluences observed by GBM. We also provide spectral and temporal analyses of the catalog. The new candidate sources provide targets for X-ray follow-up that could reveal previously unidentified Galactic magnetars. More broadly, this work demonstrates how combining instruments with complementary capabilities can maximize the scientific return of high-energy transient observations.
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Earth and Planetary Astrophysics

JWST and HST Confirm Transit Timing Variations for the Ultra-Hot Jupiter TOI-2109 b

Michael Greklek-McKeon, Julie Inglis, Nicole L. Wallack et al. (+9 more)

Ultra-hot Jupiters are a rare yet valuable subset of exoplanets that can help elucidate both the internal properties of their host stars as well as the orbital evolution of close-in planets. An extreme among extremes, TOI-2109 b is a super-Jupiter ($1.347 \pm 0.047 R_{\rm Jup}$, $5.02 \pm 0.75 M_{\rm Jup}$) with the shortest orbital period (0.67247479 $\pm$ 0.00000028 days) and the fastest predicted orbital decay rate of any known giant planet. Previous observations hinted at a quadratic long-term trend in the transit timing variations (TTVs) consistent with orbital decay, as well as short-term sinusoidal TTVs consistent with a near-resonant planetary companion that would indicate a dynamically quiescent migration pathway. Here, we combine archival ground-based, TESS, and CHEOPS photometry with new transit and eclipse data from HST and JWST to update the TTV analysis. We find very strong evidence for sinusoidal TTVs over a linear ephemeris ($\Delta$BIC of 33.6), consistent with a nearby planetary companion as suggested by J.-V. Harre et al. 2024, and rule out several non-planetary scenarios that could explain the sinusoidal TTVs. We also find strong evidence of a quadratic TTV trend ($\Delta$BIC of 6.75) consistent with an orbital decay rate of -3.46 $\pm$ 1.17 ms/yr and a stellar tidal quality factor of 2.13$^{+1.18}_{-0.61} \times10^7$, though we cannot rule out line-of-sight acceleration as the cause of the quadratic trend. If our results are confirmed, TOI-2109 b would be the only known exoplanet besides WASP-12 b with a decaying orbit and the most extreme of an ultra-rare class of close-in giant planets with nearby companions.
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All authors Michael Greklek-McKeon, Julie Inglis, Nicole L. Wallack, Shreyas Vissapragada, Ian Wong, John R. T. Allen, Yayaati Chachan, Fei Dai, Guangwei Fu, Tiffany Kataria, Thaddeus D. Komacek, Johanna K. Teske

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

The universe as a superconductor: How to search for a photon mass

Andrei Gruzinov, Anson Hook and Junwu Huang

We revisit the bounds on the photon mass when it arises from an Abelian Higgs mechanism rather than a Proca term. Because the higgs is necessarily millicharged and light, the phase of the theory (Meissner, vortex, or symmetry-restored) depends on the ambient magnetic field, so the photon mass an experiment measures depends on the environment it is performed in. We classify existing experiments by the phases in which they apply, in analogy with Type I and Type II superconductors. For Type I photon masses, magnetic fields in galaxies and the intergalactic medium can restore the symmetry everywhere, allowing a vacuum photon mass as large as $0.3 \,{\rm MeV}$. Regions of photon mass as large as $10^{-5}\, {\rm eV}$ could be present in the Universe, and measurement of frequency dependent optical depth can potentially reveal these regions. For Type II photon masses, we show that the strongest constraints mainly arise from the requirement that the galactic dynamo generates the observed magnetic fields, which we derive by generalizing magnetohydrodynamics to a nonzero photon mass. Since the terrestrial magnetic field restores the symmetry in much of the remaining parameter space, laboratory searches performed inside large magnetically shielded volumes, or in space, could probe photon masses invisible to any experiment on Earth. Measurements of distant light sources, in particular, fast radio bursts, also offer unique sensitivity to parameters invisible to lab experiments.
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Astrophysics of Galaxies

Galaxies Below the Fundamental Metallicity Relation Are Morphologically Disturbed: Merian H$\alpha$ Morphologies and DESI Metallicities

Abby Mintz, Jenny E. Greene, Shany Danieli et al. (+8 more)

Empirical results have revealed a connection between a galaxy's metallicity, mass, and star formation rate, known as the fundamental metallicity relation (FMR), in which metallicity increases with stellar mass and decreases with SFR. Physical interpretations of the FMR suggest that actively star-forming galaxies are fueled by pristine gas, likely obtained via IGM accretion or minor mergers. Here we demonstrate the value of galaxy morphology as an additional axis in the FMR. Using medium-band imaging from the Merian Survey, we construct spatially resolved maps of stellar continuum and H$\alpha$ emission for a large sample of galaxies with DESI DR1 spectra, reaching stellar masses down to $10^8$ M$_\odot$. We measure non-parametric morphological parameters from the emission maps and derive gas-phase oxygen abundances from the spectra using strong-line calibrations. We fit a series of simple linear models to explore correlations among the metallicity, stellar mass, sSFR, and morphological parameters. We find that galaxies that are more metal-poor than predicted by the FMR appear particularly disturbed. At fixed stellar mass and sSFR, metallicity is inversely correlated with the asymmetry of both the continuum and H$\alpha$ morphology. The observed trends – and the existence of particularly metal-poor, morphologically disturbed, highly star-forming galaxies – are consistent with external burst triggering. Our results indicate that a galaxy's morphology is linked to its metallicity and star formation history, providing an additional observational probe of the physical drivers of elevated star-formation in low-mass galaxies.
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All authors Abby Mintz, Jenny E. Greene, Shany Danieli, Erin Kado-Fong, Alexie Leauthaud, Jiaxuan Li, Yifei Luo, Annika H. G. Peter, Joy Bhattacharyya, Mingyu Li, Akaxia Cruz

Astrophysics of Galaxies

DIISC-VII: Linking Radial Gas Motions to Anomalously Low Metallicity Star-forming Regions in the XUV Disk of NGC 3344

Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro et al. (+4 more)

We present evidence connecting anomalously low-metallicity regions to radial gas inflows in the extended ultraviolet (XUV) disk of the galaxy NGC 3344. Anomalously low-metallicity H II regions are hypothesized to result from the accretion of metal-poor gas, but a direct link between gas flows and low metallicity gas has not been previously established. We use high-resolution H I-21cm imaging from the Very Large Array to trace neutral gas kinematics and multi-slit optical spectroscopy from the MMT to trace the gas-phase metallicity of 76 H II regions in NGC 3344. The galaxy exhibits a negative radial metallicity gradient of $-0.378$ dex $\mathrm{R}_{25}^{-1}$, with H II regions in the XUV disk showing nearly twice the metallicity scatter of those in the inner disk and several showing an anomalously low metallicity. Modeling the H I disk as tilted rings with 3DBarolo, we find gas moving radially inwards within the XUV disk at an average radial velocity of 6 $\mathrm{km\ s^{-1}}$, likely fueling star formation and diluting the metallicity, thereby producing anomalously low metallicity regions. Chemical evolution models indicate that the gas fraction, effective yield, and mass-loading factor profiles are disrupted at the onset of the XUV disk, as expected from recent gas flows. This example is the first direct detection of how radial gas flows can support stellar disk expansion and cause inside-out galaxy growth.
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All authors Alejandro J. Olvera, Sanchayeeta Borthakur, Enrico M. Di Teodoro, Kanak Saha, Mansi Padave, Hansung B. Gim, Emmanuel Momjian

Instrumentation and Methods for Astrophysics

EPIMETHEUS: Effective PSF inferred from mosaics

Pietro Benotto, Benedetta Vulcani and Vittoria Altomonte

Accurate knowledge of the point spread function (PSF) is essential for a wide range of astronomical applications, from astrometry to precision photometry. However, deriving a robust average effective PSF (ePSF) from astronomical mosaics is particularly challenging due to the superposition of exposures taken at different epochs, under different observing conditions, and with varying position angles (PAs). To address this issue, we present EPIMETHEUS, an open-source Python library designed to manage the entire ePSF construction workflow, from initial star selection to final model generation. Built with a modular architecture, EPIMETHEUS avoids black-box methodologies, ensuring full transparency and giving the user complete control over the stellar sample to use for the ePSF building to meet specific scientific requirements. The software can process multiple images or mosaics simultaneously to retrieve the ePSF, a crucial feature when individual fields lack a sufficient number of bright, unsaturated stars. Candidate stars can be automatically filtered based on orientation and light concentration, with options for manually excluding stars through a semi-automatic visual inspection. Although EPIMETHEUS is specifically optimised to handle the roto-translation complexities inherent to multi-epoch mosaics, it is versatile and can be equally applied to derive ePSFs from simpler, single-orientation images where rotational corrections are not required. Finally, to demonstrate the software's capabilities and provide an immediate resource, we release empirical ePSFs for standard HST and JWST filters across the COSMOS, UDS, Abell 2744, and GOODS-S fields.
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High Energy Astrophysical Phenomena

Compact Object Mergers and Micro-Tidal Disruption Events: A Multi-Messenger Probe of Dense Stellar Environments

Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna et al. (+1 more)

Dense stellar environments such as globular clusters and young massive clusters produce both compact-object mergers detectable in gravitational waves and tidal disruption events observable electromagnetically. We investigate compact-object mergers, tidal disruption events, and micro-tidal disruption events ($\mu$TDEs) in these environments using rapid Monte Carlo star-cluster simulations with the Rapster code, extended with a unified treatment of neutron-star (NS) and black-hole (BH) spin evolution under disk accretion across the NS-to-BH transition, as well as new dynamical channels for disruptions by single compact objects and by BH-BH binaries. Simulating $10^5$ clusters across ten model variations and two formation histories, we find a BH-BH merger-rate density peaking at $z\approx2$-$3$ at several tens ${\rm Gpc}^{-3}\,{\rm yr}^{-1}$, consistent with the local LVK rate, while the cumulative number of $\mu$TDEs exceeds that of mergers by a factor of a few. Since we include only dynamically formed binaries, $\approx90\%$ of $\mu$TDEs proceed through single compact-object-star encounters, and our rates are conservative lower limits. Prograde accretion during $\mu$TDEs spins up compact objects, providing a purely dynamical, randomly oriented pathway for producing high-spin BHs, and can drive accretion-induced collapse of NSs to BHs that populate the lower mass gap.
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All authors Konstantinos Kritos, Francesco Iacovelli, Rosalba Perna, Emanuele Berti

Astrophysics of Galaxies

Euclid Quick Data Release (Q1): Disc breaks highlight the structural evolution of galaxies through time

Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron et al. (+301 more)

Changes in the slope of the radial surface brightness profiles of disc galaxies, or disc breaks, encode valuable information about the processes driving disc formation and growth. Until now, due to the resolution and depth required, statistical studies of break types have been limited mostly to the local Universe. We aim to study the structural properties and redshift evolution of disc breaks in a large and statistically representative sample of galaxies out to redshift z=1 using the superb depth and resolution of Euclid. We develop an automatic pipeline to extract and analyse surface brightness profiles of 8748 disc galaxies selected from the Euclid Q1 dataset. The pipeline includes advanced masking, surface brightness profile extraction, integrated photometry and structural parameter measurements, and piecewise modelling to classify galaxies into Types I (pure exponential), Type II (down-bending), Type III (up-bending), and composite break (e.g., Type~II+III, Type~II+II, etc) profiles. We quantify structural parameters such as scale lengths, break radii, and surface brightness levels, and analyse their distributions and redshift dependence. Our automatic method produces reliable masks and deep surface brightness profiles, and classifies galaxy profiles with an estimated accuracy of 70%. Using a subsample of 4385 galaxies with reliable classifications, we find that the most common profiles are Types II, II+III, I, and III. We find substantial evolution in the fraction of disc breaks with time. Type II profiles dominate at low redshift (50%), while Types III and II+III profiles increase in frequency with lookback time, reaching 30% each at z~1. Our study provides the first statistically robust measurement of the evolution of disc break types over 5 Gyr. The observed trends support a scenario in which secular processes replace environmental influences as galaxies mature.
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All authors Euclid Collaboration: P. M. Sanchez-Alarcon, J. Román, S. Comeron, J. H. Knapen, M. Huertas-Company, F. Buitrago, M. Montes, A. S. Borlaff, P. M. Marcum, J. Junais, E. Duran-Camacho, M. N. Le, M. Dunn, H. Dannerbauer, B. Altieri, A. Amara, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, M. Bolzonella, E. Branchini, M. Brescia, J. Brinchmann, S. Camera, G. Cañas-Herrera, V. Capobianco, C. Carbone, J. Carretero, S. Casas, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, A. Costille, F. Courbin, H. M. Courtois, M. Cropper, A. Da Silva, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, F. Dubath, C. A. J. Duncan, X. Dupac, S. Dusini, S. Escoffier, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, F. Finelli, S. Fotopoulou, M. Frailis, E. Franceschi, M. Fumana, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. Gwyn, W. G. Hartley, S. V. H. Haugan, J. Hoar, H. Hoekstra, W. Holmes, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, B. Joachimi, E. Keihänen, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, M. Magliocchetti, G. Mainetti, D. Maino, E. Maiorano, O. Mansutti, S. Marcin, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, N. Mauri, E. Medinaceli, S. Mei, M. Melchior, Y. Mellier, M. Meneghetti, E. Merlin, G. Meylan, P. Monaco, A. Mora, M. Moresco, C. Moretti, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, C. Padilla, K. Paech, S. Paltani, F. Pasian, W. J. Percival, V. Pettorino, A. Pezzotta, S. Pires, G. Polenta, M. Poncet, L. A. Popa, C. Porciani, L. Pozzetti, F. Raison, A. Renzi, J. Rhodes, G. Riccio, I. Risso, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, D. Sapone, B. Sartoris, P. Schneider, T. Schrabback, A. Secroun, G. Seidel, S. Serrano, P. Simon, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, J. Steinwagner, P. Tallada-Crespí, A. N. Taylor, H. I. Teplitz, I. Tereno, N. Tessore, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, L. Valenziano, J. Valiviita, T. Vassallo, G. Verdoes Kleijn, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, E. Zucca, V. Allevato, M. Ballardini, E. Bozzo, C. Burigana, R. Cabanac, M. Calabrese, A. Cappi, J. A. Escartin Vigo, J. Martín-Fleitas, S. Matthew, R. B. Metcalf, A. A. Nucita, M. Pöntinen, V. Scottez, M. Sereno, M. Tenti, M. Viel, M. Wiesmann, Y. Akrami, I. T. Andika, S. Anselmi, M. Archidiacono, F. Atrio-Barandela, P. Bergamini, D. Bertacca, M. Bethermin, A. Blanchard, L. Blot, M. Bonici, M. L. Brown, S. Bruton, A. Calabro, B. Camacho Quevedo, F. Caro, C. S. Carvalho, T. Castro, F. Cogato, S. Conseil, T. Contini, A. R. Cooray, O. Cucciati, G. Desprez, A. Díaz-Sánchez, S. Di Domizio, J. M. Diego, P. Dimauro, P.-A. Duc, M. Y. Elkhashab, A. Enia, Y. Fang, A. Finoguenov, F. Fontanot, A. Franco, K. Ganga, J. García-Bellido, T. Gasparetto, V. Gautard, R. Gavazzi, E. Gaztanaga, F. Giacomini, F. Gianotti, G. Gozaliasl, M. Guidi, C. M. Gutierrez, A. Hall, C. Hernández-Monteagudo, H. Hildebrandt, J. Hjorth, J. J. E. Kajava, Y. Kang, V. Kansal, D. Karagiannis, J. Kim, C. C. Kirkpatrick, S. Kruk, L. Legrand, M. Lembo, F. Lepori, G. Leroy, G. F. Lesci, J. Lesgourgues, L. Leuzzi, T. I. Liaudat, A. Loureiro, J. Macias-Perez, E. A. Magnier, F. Mannucci, R. Maoli, C. J. A. P. Martins, L. Maurin, G. Morgante, K. Naidoo, P. Natoli, A. Navarro-Alsina, S. Nesseris, D. Paoletti, F. Passalacqua, K. Paterson, A. Pisani, D. Potter, S. Quai, M. Radovich, G. Rodighiero, S. Sacquegna, M. Sahlén, D. B. Sanders, E. Sarpa, A. Schneider, M. Schultheis, D. Sciotti, E. Sellentin, F. Shankar, L. C. Smith, J. G. Sorce, K. Tanidis, G. Testera, R. Teyssier, S. Tosi, A. Troja, M. Tucci, C. Valieri, A. Venhola, D. Vergani, G. Verza, P. Vielzeuf, N. A. Walton, D. Scott

High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Precise QCD Predictions for the Scotogenic Model at Colliders

Mohammed Boukidi, Camila Ramos and Richard Ruiz

Motivated by the anticipated data rates of the high-luminosity phase of the Large Hadron Collider, we report the first predictions up to next-to-leading order in quantum chromodynamics with parton-shower matching for the production and decay of scalars and heavy neutrinos from the Scotogenic model for neutrino masses and dark matter at $\sqrt{s}=14$ TeV and $\sqrt{s}=100$ TeV. We carry out our simulations using the FeynRules+MadGraph5\_aMC@NLO+Pythia8 pipeline. As a byproduct, we report the public release of the SM\_Scoto Universal FeynRules Object libraries for modeling the Scotogenic model in high-energy processes. We comment on prospects of observing new rare $Z$ decays at future $e^+e^-$ collider facilities as well as on the production of new particles at a multi-TeV $\mu^+\mu^-$ collider.
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Earth and Planetary Astrophysics

Revealing the Shiny Nature of Lava Worlds: Small Planet Phase Curves with TESS

Brandon Park Coy, Michael Zhang, Fei Dai et al. (+1 more)

Recent thermal emission observations suggest that `lava worlds'–Earth-sized exoplanets hot enough to melt their silicate surfaces–have atmospheres on a population-level. This evidence comes from measured dayside brightness temperatures much lower than expected for a dark, maximally hot bare rock. However, these results are degenerate between a thick atmosphere advecting heat to the planet's nightside or a high albedo reflecting incoming radiation. This degeneracy can be resolved through visible light phase curve observations, which can constrain how much light is reflected by the planet. Here, we present a population-level analysis of the visible-light TESS phase curves of $R\lesssim5\,R_{\oplus}$ exoplanets. We select the population by defining a `Reflection Spectroscopy Metric' meant to quantify the relative signal-to-noise of reflected light observations. We report new $>3\,\sigma$ detections of the TESS phase curve signals of LTT 9779 b and the lava worlds TOI-2431 b, TOI-561 b, 55 Cancri e, K2-141 b, and TOI-1444 b. We use these results and previous results from Kepler and CHEOPS to homogeneously derive geometric albedos for these planets, revealing that lava worlds generally show high albedos compared to the low geometric albedos measured for hot Jupiters at similar temperatures. These results support an emerging picture of reflective silicate clouds on these worlds cooling their daysides. The upcoming PLATO mission is expected to tightly constrain the reflected light phase curves of lava worlds.
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All authors Brandon Park Coy, Michael Zhang, Fei Dai, Qiao Xue

Solar and Stellar Astrophysics

Spectroscopic Study of the Circularly Polarised Radio Source TYC 2834-1385-1: An Active Binary

Tamara A. S. Bleeker, Alexander Hoogerbrug, Elise Koo et al. (+2 more)

Close binaries with active chromospheres have recently been shown to emit circularly polarised radio emission at low frequencies, motivating detailed studies of their orbital properties. We present high-resolution ($R=85,000$) optical spectroscopy of TYC 2834-1385-1, a previously unclassified radio source, obtained with the HERMES spectrograph on the Mercator Telescope. We identify the source as a double-lined spectroscopic binary and measure radial velocities from both metallic absorption and Ca II emission lines. We find an orbital period of $P=3.601\pm0.002$ days and nearly equal radial-velocity semi-amplitudes for the two components. The system exhibits strong Ca II H and K emission, which is consistent with a BY Dra-type binary containing two similar late-G/early-K main-sequence stars, with a preliminary classification of K0V. This represents one of the first spectroscopic confirmations of a chromospherically active binary following its identification in a low-frequency radio survey.
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All authors Tamara A. S. Bleeker, Alexander Hoogerbrug, Elise Koo, Rudy Wijnands, Joseph R. Callingham

Astrophysics of Galaxies

The First Blind Survey of Intervening NaI Absorbers: Incidence and Cosmic Evolution with DESI

Abhijeet Anand and Sowgat Muzahid

We present the first blind statistical survey of intervening NaI absorbers over the last $\simeq3$~Gyr using quasar spectra from the Dark Energy Spectroscopic Instrument Data Release~1. We identify 3636 NaI D doublets at $0.01\lesssim z_{\rm abs}\lesssim0.27$ along 214,035 quasar sightlines. We quantify the survey selection function through end-to-end injection–recovery tests and estimate the residual contamination from visual inspection. The completeness reaches 50% at a rest-equivalent width of the NaI $\lambda5891$ line, $W_{5891}\simeq0.95$ Angstrom, and the catalog-weighted purity is $\simeq77\%$. For the fiducial sample with $0.95<W_{5891}<3.5$ Angstrom, we measure the equivalent-width distribution ($f(W_r)$), absorber incidence ($dN/dX$), and cosmic NaI mass density ($\Omega_{\rm Na\,I}$). From $z\simeq0.25$ to $z\simeq0.03$, $dN/dX$ rises by a factor of $\simeq3.4$ in both rest-equivalent-width subsamples, split at the median $W_{5891}=1.41$ Angstrom, while $\Omega_{\rm Na\,I}$ increases by a similar factor. This corresponds to a smooth increase in the product of the comoving number density of NaI-absorbing hosts ($n_{\rm com}$) and the cross-section of the NaI-bearing gas ($\sigma_{\rm eff}$) with cosmic time. The similar evolution of $\Omega_{\rm Na\,I}$ and $dN/dX$ indicates little change in the mean measured NaI column density per absorber. We also find preliminary evidence that NaI absorbers are associated with foreground galaxies at relatively small projected separations and that their quasar sightlines are redder than matched controls. These results support a picture in which NaI traces dense neutral gas in and around galaxies. Dedicated galaxy surveys and CGM/ISM simulations can test the inferred incidence and cross-section, while spectral stacking can probe the associated gas and dust.
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Astrophysics of Galaxies

The BRIDGE Survey. I. Metallicities and Physical Properties of Gas Probing the Circumgalactic Medium at Cosmic Noon

Saloni Deepak, Nicolas Lehner, J. Christopher Howk et al. (+3 more)

We present BRIDGE-I, a metallicity survey of \HI-selected absorbers probing “CGM-like” gas ($16.4\leq \log N_{\rm HI}<20.3$) at Cosmic Noon ($1\leq z \leq2.2$), the epoch of peak star formation and AGN activity. Combining archival HST UV spectra with Keck/HIRES and VLT/UVES optical spectra, we estimate metallicities and physical conditions for 105 absorbers. The Cosmic Noon metallicity distribution (median $[\rm{X/H}]=-1.19$) is statistically indistinguishable from that at $z<1$ ($-1.18$) but differs significantly from $z>2.2$ ($-2.02$). This plateau is driven by the most diffuse absorbers ($16.4\leq \log N_{\rm HI}<17.2$), which reach their $z<1$ enrichment level by Cosmic Noon, whereas denser absorbers remain more metal-poor than their $z<1$ counterparts and continue to be enriched at later times. Unlike at $z>2.2$, no absorber falls below $[\rm{X/H}]=-3.5$, indicating no pristine CGM-like gas at Cosmic Noon. Absorbers in BRIDGE-I trace overdensities of $400\lesssim \delta_b\lesssim2200$, higher than at $z>2.2$. Mean $N_{\rm HI}$ differs by a factor of 400 across absorber types, but mean total hydrogen column by only 2.5, as higher $N_{\rm HI}$ is offset by a higher neutral fraction. The absorber classes thus differ in ionization state and metallicity rather than the total gas content. A metallicity floor of $[\rm{X/H}]\sim-2.0$ emerges for $\log N_{\rm HI}>19.0$ absorbers, indicating that denser, more ISM-like gas is well mixed as a population, while more diffuse gas retains a metal-poor population that is not yet fully mixed.
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All authors Saloni Deepak, Nicolas Lehner, J. Christopher Howk, John O'Meara, Celine Peroux, J. Xavier Prochaska

Astrophysics of Galaxies

Comparing phylogenetic trees of stars with spectral graph distances

Theosamuele Signor, Matias Neto, Paula Jofré et al. (+9 more)

Phylogenetic trees offer a hierarchical representation of chemical similarities among stars, from which their evolutionary histories can, in principle, be reconstructed. Simulation-based work suggests that phylogenetic trees built under different chemical evolution scenarios carry distinguishable structural imprints, but whether existing methods can detect this signal in practice is unclear. We evaluate distance measures, both classical tree-based and graph-theoretical, for comparing phylogenetic trees, seeking measures robust to observational noise that separate trees built from populations with distinct chemical enrichment histories. We construct Neighbor-Joining trees from chemical abundance vectors of solar twins and of stars associated with the Milky Way (MW) disk, Gaia-Sausage-Enceladus (GSE), and the Sagittarius dwarf spheroidal galaxy (Sgr). Two benchmark tests assess stability under input perturbations within the same evolutionary history and discriminative power between distinct stellar populations used as proxies for different evolutionary histories. Tree metrics rapidly saturate under perturbations of order the typical uncertainty ($\approx2\sigma$, or $\approx0.05$ dex per element) and fail to distinguish trees when leaf sets differ. In contrast, spectral distances vary smoothly with perturbation amplitude and provide a label-invariant method for comparing trees built from disjoint sets of stars. Among the spectral measures evaluated, the Laplacian spectral distance shows the most consistent separation across population pairs, while the normalized variant is weakest. Applied to MW, GSE, and Sgr stars, spectral measures recover a distance ordering consistent with their known chemical enrichment histories. This framework also provides a route to comparing observed enrichment histories against simulations to identify those that best reproduce the observed tree structure.
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All authors Theosamuele Signor, Matias Neto, Paula Jofré, Sara Vitali, Xia Hua, Patricia B. Tissera, Claudia Aguilera-Gómez, Payel Das, Brian Tapia-Contreras, Robert M. Yates, Luis Martí, Nayat Sánchez-Pi