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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 22 April

Instrumentation and Methods for Astrophysics

Photometric Super-Resolution for Improving Galaxy Morphological Measurements using Conditional Generative Adversarial Networks

Samuel Kahn, Ryan Hausen, Hubert Bretonnière et al. (+2 more)

The measurement of galaxy morphological parameters from astronomical images features in a wide range of modern analyses, including galaxy evolution and cosmological weak lensing studies. The precision and accuracy of morphological parameter estimation can be influenced by several key factors. The effective seeing of the image, summarized by the point spread function (PSF), limits how galaxy features or light profiles are resolved. The pixel scale of the detector also influences the resolution and the amount of statistical information available for a given object. The depth of the observations determines the signal-to-noise ratio of the image. Improving each of these factors is very costly, either in terms of detector upgrades, observatory design, or observing time. Here, we develop a conditional generative adversarial network, called Neo, trained to transform existing ground-based images into sharper, finer-scale images comparable to space-based image quality. We demonstrate that Neo improves the accuracy of measured morphological parameters by factors of $2$-$10$ when trained to translate Subaru Hyper Suprime-Camera (HSC) images to approximate Hubble Space Telescope (HST) data. Neo is designed for applicability to ongoing, large-scale surveys such as the Legacy Survey of Space and Time (LSST) conducted by Vera C. Rubin Observatory in combination with space telescopes such as HST, James Webb Space Telescope, and Nancy Grace Roman Space Telescope. These results suggest that Neo could be used to improve both cosmological and galaxy evolution analyses based on massive, ground-based survey datasets like LSST. The model code is open source and available at https://purl.archive.org/neo/code.
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All authors Samuel Kahn, Ryan Hausen, Hubert Bretonnière, Nicole Drakos, Brant Robertson

Instrumentation and Methods for Astrophysics

Science from the In Situ Exploration of the Proxima Centauri System

T. Marshall Eubanks, Jean Schneider, Bruce Bills et al. (+11 more)

In the future interstellar exploration at near-relativistic speeds will be possible using beamed energy laser propulsion. With this, spacecraft as small as gm mass picospacecraft become candidates for the exploration of deep space, with a trade space of velocity and mission duration versus mass. Here, we examine the potential science return from interstellar expeditions with Coracle laser-sail picospacecraft swarms and show how even with fast flybys at near relativistic velocities, a picospacecraft swarm could deliver gigapixel resolution of the target exoplanets. Our mission target is the planet Proxima b in the habitable zone (HZ) of the red dwarf Proxima Centauri, the tertiary (and nearest) component of the nearest star system, {\alpha} Centauri. We explore science returns from such an expedition, both en route to Proxima and at the Proxima system, and conclude that initial small spacecraft expeditions would provide a substantial science return, including the ability to detect surface biology or a technological civilization, should either or both be established on the target planet.
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All authors T. Marshall Eubanks, Jean Schneider, Bruce Bills, W. Paul Blase, Andreas M. Hein, Pierre Kervella, Adam Hibberd, Robert G. Kennedy III, Manasvi Lingam, Philip Lubin, Philip D. Mauskopf, Thomas J. Mozdzen, Richard M. Scott, Slava G. Turyshev

High Energy Astrophysical Phenomena

Fast-Cooling Synchrotron in Decaying Magnetic Fields: Implications for the GRB Spectral Distribution

Jia-Ming Chen, Ke-Rui Zhu, Zhao-Yang Peng et al. (+5 more)

The prompt-emission spectra of gamma-ray bursts (GRBs) are commonly described by the empirical Band function. The typical low-energy spectral index is $\sim -1$, which poses a challenge to standard synchrotron radiation models. We systematically investigate a fast-cooling synchrotron model with a decaying magnetic field and test, within an observation-consistent pipeline, whether it reproduces the Band-fit parameter distributions in the GBM catalog, in a statistical sense. We solve the electron continuity equation with synchrotron, adiabatic, and synchrotron self-Compton cooling to obtain the time-dependent electron distribution and synthetic spectra; we then forward-fold through the GBM response matrices and recover $(\alpha, \beta, E_p)$ with Band fits. We find that magnetic-field decay can harden the recovered $\alpha$ relative to the fast-cooling limit in part of parameter space, but the effect is not robust and is sensitive to the location of $E_p$ within the finite band and to spectral curvature; varying key physical scales reshapes the recovered $\alpha$ distribution, indicating that catalog $\alpha$ often represents an effective in-band slope rather than the asymptotic index. SSC cooling provides modest additional hardening and, in our setups, does not stabilize $\alpha$ near the observed peak. Using Monte Carlo samples designed to mimic the observations, the model yields $\alpha$ mostly between $-1.5$ and $-0.8$, but remains centered around $\alpha \approx -1.5$. Overall, while decaying-field fast-cooling synchrotron can partially alleviate overly soft spectra expected from standard fast-cooling synchrotron emission, it still falls short of reproducing the GBM $\alpha$ distribution at the population level, implying that additional physical processes are required.
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All authors Jia-Ming Chen, Ke-Rui Zhu, Zhao-Yang Peng, Yong-Gang Zheng, Yun-Lu Gong, Shan Chang, Shi-Ting Tian, Li Zhang

High Energy Astrophysical Phenomena

Detections of nearly bias-free core shifts with 5-30 $\mu$as precisions at 8-43 GHz in BL Lacertae

Niu Liu, Jun Yang, Xiaopeng Cheng et al. (+7 more)

When a radio jet is partially optically thick in the launching region, its apparent compact core may display frequency-dependent positional shifts. High-precision astrometric measurements of core shifts enable astronomers to pinpoint the jet's origin and place tight constraints on the magnetic field. BL Lacertae, the archetypal BL Lac object, hosts a highly variable and well-collimated jet. To independently constrain its innermost core shifts, we conducted very long baseline interferometric (VLBI) observations at 8.4, 12.4, 15.2, 23.6, and 43.2 GHz. By exploiting a nearby (13.3 arcmin) steep-spectrum calibrator (NVSS J220340+420839) through inverse phase-referencing VLBI astrometry, we detect nearly unbiased two-dimensional core shift measurements with state-of-the-art precisions of 5-30 $\mu$as, which are significant at $>3\sigma$ confidence. The core shift between 8.4 and 43.2 GHz reaches 250 $\mu$as. The apparent core shifts scale with frequency as $\nu^{-1/k_r}$, implying the existence of an optically thick region in the upstream of jet. The derived core-shift index, $k_r\!=\!1.18^{+0.59}_{-0.34}$, is consistent, within uncertainties, with the canonical $k_r\!=\!1$ expected under energy equipartition between the jet particle and magnetic field energy densities, while allowing for modest deviations given that BL Lacertae was captured in a flaring state.
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All authors Niu Liu, Jun Yang, Xiaopeng Cheng, Ai-Ling Zeng, Wen Chen, Xiao-Long Yang, Xiaoyu Hong, Xia-Xuan Zhang, Jia-Cheng Liu, Zi Zhu

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

Photon and neutrino fluxes from spheroidal dwarf galaxies in a decaying DM model

A. Carrillo-Monteverde, L. López-Lozano and F. San Juan-Villegas

In this work, we investigate a decaying dark matter scenario and its associated indirect detection signatures. The model consists of a scalar singlet with a lifetime exceeding the age of the Universe. Stability is ensured by a $Z_2$ symmetry imposed on the Lagrangian, allowing decay through a non-minimal gravitational coupling. The decay of dark matter produces Standard Model particles, which subsequently yield products such as gamma rays, neutrinos, and charged particles. We computed the gamma-ray and neutrino fluxes generated by this candidate in the Milky Way and in 14 dwarf spheroidal galaxies, as well as the corresponding expected number of events in selected experiments, using dedicated numerical tools. Results are presented for three benchmark masses and three coupling values consistent with cosmological constraints, showing that the predicted signals can be observable in specific regions of parameter space.
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Astrophysics of Galaxies

Cold molecular gas distribution and kinematics in the low-metallicity dusty starburst of Mrk 996 resolved with ALMA

R. Slater, R. Amorín, J.A. Fernández-Ontiveros et al. (+10 more)

Detecting cold molecular gas in metal-poor starbursts remains a major challenge. Low carbon and oxygen abundances hinder CO formation, while low dust content reduces shielding against UV photodissociation. Consequently, CO, the main tracer of molecular gas, becomes faint or undetectable. We study the spatial distribution and kinematics of cold molecular gas in Mrk 996, a nearby low-mass Wolf-Rayet galaxy hosting a dense, low-metallicity (about 1/5 solar) and nitrogen-enriched nuclear starburst with complex ionized gas kinematics. Using ALMA observations of CO(1-0) and CO(2-1), we map the morphology and kinematics of the molecular gas and compare them with optical and UV data, tracing the ionized gas and young stellar populations. We detect compact CO clouds within 800 pc of the starburst, spatially offset from the nuclear super star cluster (SSC) and the most highly ionized regions. The CO lines are narrow and supersonic, exhibiting velocity gradients with a mild global blueshift, indicating dynamically perturbed gas without evidence for fast outflows, in contrast with the highly ionized phase. The global CO(2-1)/CO(1-0) ratio is low (R21 ~ 0.3), consistent with subthermal excitation. The millimeter continuum peaks at the SSC, while CO emission is displaced toward obscured regions, suggesting it traces dense shielded clumps. ALMA recovers about half of the single-dish flux, indicating the presence of extended, low-surface-brightness molecular gas. Using a metallicity-dependent CO-to-H2 conversion factor, we infer a molecular gas mass of a few 10^7 solar masses. The molecular gas is only weakly coupled to the stellar feedback that dominates the ionized phase. Our results support a multiphase scenario in which dense molecular clumps survive in shielded regions, while CO is photodissociated in their envelopes, leaving a significant CO-dark H2 component (Abridged).
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All authors R. Slater, R. Amorín, J.A. Fernández-Ontiveros, F.J. Sáez-Ruiz, M. S. Oey, B. L. James, M. Mingozzi, M. Llerena, M.G. del Valle-Espinosa, K. Harrington, N. Kumari, R. Sánchez-Janssen, J.M. Vílchez

High Energy Astrophysical Phenomena

SN 2007it on the RISE – a radio detection of an interacting supernova 18 years post-explosion

F. Acero, R. Z. E. Alsaberi, M. Arias et al. (+17 more)

We report the first detection of radio emission from the Type II supernova SN 2007it, located at a distance of 12.2 Mpc in NGC 5530. The observations were obtained with the Australian Telescope Compact Array (ATCA) more than 18 yr after the explosion as part of the Rebrightening in Interacting Supernova Emission (RISE) program, which monitors nearby core-collapse supernovae for late-time interaction with dense circumstellar material. SN 2007it was detected on 2026 April 8 (08:00-12:00 UTC) at 5.5 GHz with a flux density of $3.30 \pm 0.13$ mJy and at 9.0 GHz with $3.54 \pm 0.24$ mJy. Its non-detection in publicly available 0.88 GHz ASKAP data from 2026 January 11 suggests either rapidly rising emission or significant internal absorption at lower frequencies. We assess the prospects for detection at other wavelengths and encourage coordinated follow-up observations across the radio, optical, X-ray, and $\gamma$-ray band
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All authors F. Acero, R. Z. E. Alsaberi, M. Arias, J. Borowska-Naguszewska, R. Brose, C. Burger-Scheidlin, P. G. Edwards, Q. Feng, M. D. Filipovic, T. Laskar, S. Lazarevic, J. Mackey, A. Nucara, K. Rose, S. Ryder, F. Schüssler, A. Simongini, Z. J. Smeaton, I. Sushch, S. Zhu

Tuesday 21 April

Instrumentation and Methods for Astrophysics · Cross-listed from physics.pop-ph

From Anomaly to Candidate Technosignature: The Threshold Problem of the Loeb Scale

Konrad Szocik and Abraham Loeb

Recent work on the Loeb Scale has provided astronomy a structured framework for assessing anomalous interstellar objects, including a quantitative mapping of a classification ranking, its evolution with the addition of data, and a broader observational strategy for firming its verdict. What remains unclear is the epistemic and methodological meaning of the threshold built into that framework. Here we argue that the central philosophical issue is no longer whether astronomy can define such a threshold, but how a threshold already in place should regulate scientific inquiry under uncertainty. We suggest that candidate technosignature status, such as Level 4 on the Loeb Scale, should be understood as an intermediate epistemic status: stronger than permissive openness, weaker than confirmation, yet sufficient to justify methodological escalation. The argument proceeds in three steps. First, it reconstructs the recent philosophical debate through the work of Lomas, Lane, and Cowie. Second, it turns to historical cases discussed by Kaplan (2026) to show that important discoveries are often delayed not only by weak evidence, but also by paradigms, prestige, and institutional filtering. Third, it interprets candidate status as a form of structured scientific commitment under uncertainty, one that justifies intensified observation, broader hypothesis management, and more deliberate allocation of attention and resources without licensing belief in artificial origin. The paper concludes by arguing that AI should not be the arbitrator in deducing an extraterrestrial origin, but can support the detection, comparison, and prioritization of anomalies once a candidate status has been formally recognized.
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Cosmology and Nongalactic Astrophysics

Purely quadratic non-Gaussianity from tachyonic instability: Primordial black holes and scalar-induced gravitational waves

He-Xu Zhang and Mei Huang

We investigate primordial black hole (PBH) formation in a cosmological scenario where curvature perturbations follow purely quadratic non-Gaussianity, $\zeta = A(\phi^2-langle\phi^2\rangle)$, arising from tachyonic instability in multicomponent inflationary models. Within an extended Press-Schechter framework based on the compaction function, we derive the probability distribution of the linear compaction function and its asymptotic exponential tail, demonstrating that the PBH abundance is exponentially sensitive not only to the amplitude of perturbations but also to the correlation coefficient $\rho$ between the smoothed field and its radial gradient. We further find that, in this tachyonic amplification scenario, the spectral width of the curvature power spectrum plays a decisive role in avoiding PBH overproduction: broad spectra yield mildly negative $\rho$ and fail to suppress PBH formation, while sufficiently narrow spectra drive $\rho \to -1$, resulting in exponential suppression while maintaining a sizable gravitational-wave signal. Thermal inflation serves as a benchmark for asteroid-mass PBH dark matter and high-frequency scalar-induced gravitational waves potentially detectable by future space-based interferometers, but its typically broad spectra make it challenging to reconcile pulsar timing array observations with PBH constraints.
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Astrophysics of Galaxies

Unraveling Chemical Enrichment in Extreme Emission-Line Galaxies: A Multi-Element Bayesian View of Bursty Star Formation and Galaxy Evolution in DESI

Razieh Emami, James A. A. Trussler, Tiger Yu-Yang Hsiao et al. (+11 more)

Extreme emission-line galaxies (EELGs) probe chemical enrichment in low-mass, bursty systems where star formation, feedback, and gas accretion are poorly constrained. Using DESI DR1, we select 23 nearby EELGs with detections of 19 ionic species (S/N $\geq$ 4), stellar masses $ M_* \geq 10^7 M_{\odot}$, and extreme H$\alpha$ and [O III] 5007 equivalent widths (EW $\geq$ 500 Angstrom). We infer non-parametric star-formation histories and fit a Bayesian single-zone chemical-evolution model to O, N, Ne, S, and Ar, allowing time-dependent star-formation efficiency, outflow mass loading, and evolving inflow metallicity. We find short depletion timescales and large mass-loading factors, indicating rapid gas cycling in a burst-driven, non-equilibrium regime, with depletion times below Kennicutt-Schmidt expectations. Star-formation efficiency and outflows are well constrained, while inflow metallicity is weaker due to degeneracies with metal production. Abundance ratios isolate physical drivers: star-formation efficiency sets evolutionary tracks, outflows regulate metal retention and X/O normalization, and inflow metallicity sets baseline enrichment. N/O strongly constrains burst timing and gas flows, Ne/O remains nearly invariant, and S/O and Ar/O show intermediate sensitivity. These results demonstrate that multi-element abundances provide a direct probe of baryon-cycle processes in extreme low-mass starbursts.
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All authors Razieh Emami, James A. A. Trussler, Tiger Yu-Yang Hsiao, Kaley Brauer, Lars Hernquist, Randall Smith, Douglas Finkbeiner, Fengwu Sun, Rebecca Davies, James F. Steiner, Mark Vogelsberger, Tobias Looser, Grant Tremblay, Letizia Bugiani

Earth and Planetary Astrophysics

Feeling the Pressure: Effects of Formation Pressure on the Physical Properties of Titan Haze Analogs

Adis Husić, Xinting Yu, Ryan C. Blase et al. (+3 more)

The Cassini-Huygens mission detected large negative ions in Titan's ionosphere at pressures as low as $10^{-6}$ torr. These ions ultimately polymerize to form Titan's complex organic haze particles, which are observed throughout the atmosphere and potentially on the surface. Laboratory analogs of these hazes, known as tholins, have been used to study Titan's aerosols; however, most are produced at much higher pressures. The influence of formation pressures on key physical properties – such as particle size, density, surface energy, and mechanical strength – remains poorly constrained. These properties govern the haze's aggregation efficiency, radiative behavior, and surface-atmosphere interactions, shaping Titan's climate and surface. To investigate the effects of formation pressure, we generate tholins using a newly developed cold plasma discharge system. A 95% nitrogen and 5% methane gas mixture is exposed to plasma at two pressures, 1 torr and 0.125 torr. For both samples, we measure the production rate, particle size, morphology, density, surface free energy, Young's modulus, and nanoindentation hardness. While particle size, morphology, surface energy, and Young's modulus are similar across both pressures, tholins produced at lower pressure exhibited a threefold lower production rate, but a higher density and nanoindentation hardness. These variations likely reflect pressure-dependent changes in chemical structure, porosity, and mechanical strength. Because Titan's hazes form at much lower pressures than investigated here, actual haze particles are potentially even denser and mechanically stronger than our analogs, with implications for aerosol aggregation, aeolian and fluvial transport, and surface modification on Titan.
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All authors Adis Husić, Xinting Yu, Ryan C. Blase, Edward L. Patrick, Eric Austin, Alan G. Whittington

Astrophysics of Galaxies

MAUVE-MUSE: Ionization and Kinematic Signatures of Environmental Effects on Virgo Cluster Disks

Toby Brown, Luca Cortese, Barbara Catinella et al. (+18 more)

We present early science results from the MAUVE (Multiphase Astrophysics to Unveil the Virgo Environment) program which targets 40 Virgo Cluster galaxies to investigate the effect of environment on the interstellar medium (ISM) at ~100 pc scales. From 12 galaxies in the MAUVE-MUSE early sample, we find systematically elevated line ratios compared to PHANGS-MUSE field disks, with higher medians of [N II]/H$\alpha$ (0.75 vs. 0.50), [S II]/H$\alpha$ (0.57 vs. 0.49), and [O III]/H$\beta$ (1.04 vs. 0.68). Spatially resolved BPT diagrams show 74% of MAUVE-MUSE spaxels ionized by sources other than H II regions, versus 61% in the field, and we find these ionization differences to be closely coupled to broadened kinematics. 44% of MAUVE-MUSE spaxels exceed H$\alpha$ $\sigma_{LOS} = 40$ km/s (vs. 26% in the field), driven mainly by non-star-forming gas with $\sigma_{LOS}$ between 40 and 80 km/s, consistent with enhanced contribution of diffuse ionized gas (DIG). A subdominant tail of 5% of spaxels at $\sigma_{LOS} > 100$ km/s, largely absent in PHANGS-MUSE (1%), points to shocks or turbulent mixing layers from intracluster interactions. Our results show that environmental quenching primarily suppresses star formation, unveiling DIG as the dominant ionized component in cluster disks. The elevated line ratios and broadened kinematics observed in the MAUVE sample reflect the physical state of the ISM in the absence of vigorous star formation, rather than widespread direct environmental excitation. The observed shock-like emission provides an additional, secondary contribution likely driven by active interactions with the intracluster medium.
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All authors Toby Brown, Luca Cortese, Barbara Catinella, A. Fraser-McKelvie, Adam B. Watts, Amirnezam Amiri, Alessandro Boselli, Woorak Choi, Aeree Chung, Timothy A. Davis, Eric Emsellem, Pavel Jáchym, María J. Jiménez-Donaire, Tutku Kolcu, Bumhyun Lee, Andrei Ristea, Jesse van de Sande, Kristine Spekkens, Sabine Thater, Christine D. Wilson, Nikki Zabel

High Energy Astrophysical Phenomena

Circumbinary Discs as the Origin of Circumstellar Material around Interacting H-poor Supernovae and Fast Blue Optical Transients

Ryotaro Chiba, Semih Tuna, Brian D. Metzger et al. (+1 more)

Around 10 % of hydrogen-poor supernovae explode inside compact ($\sim 10^{15}$ cm), massive ($\sim 0.1 \ \mathrm{M_\odot}$) circumstellar material (CSM), signalling an episode of enhanced pre-explosion mass loss whose mechanism remains unclear. The extreme members of this population are considered to constitute some of the Fast Blue Optical Transients (FBOTs), which exhibit rapid rise times of $\sim$ few days and high peak luminosity $\sim 10^{44} \ \mathrm{erg}$. Recent binary evolution calculations show that the expansion of helium stars during their latest evolutionary stages can trigger a rapid but stable mass-transfer episode that can form a dense circumbinary disc (CBD) that may explain the observed dense CSM. However, a detailed, quantitative analysis of this process and the resulting CBD properties such as its mass, radius and density profile has not yet been undertaken. We present a set of models that solve the viscous evolution of such a CBD under time-dependent mass injection. We find that although the injected mass is initially sub-Keplerian, a lower “accretion eigenvalue” $\chi$ prevents more mass from falling back onto the central binary. For our fiducial set of models, the CBD immediately prior to the explosion reaches a mass of $0.07-0.20 \ \mathrm{M}_\odot$, a half-mass radius of $640 - 4000 \ \mathrm{R}_\odot$, and an aspect ratio of $\theta = H/R \sim 0.1$. We also show that the interaction between SN ejecta and the CBD can power some of the fastest-evolving interacting Type Ibc SNe that can be classified as FBOTs, such as SN 2018gep or SN 2019jc. Despite uncertainties in the model parameters, our results demonstrate that CBD formation triggered by rapid, stable mass transfer is a viable mechanism to explain the dense circumstellar environments observed around rapid, hydrogen-poor interacting SNe. (abridged)
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All authors Ryotaro Chiba, Semih Tuna, Brian D. Metzger, Takashi J. Moriya

Solar and Stellar Astrophysics

The First Infrared Portrait of A Solar-Like Host Star with Debris Disk: Pioneering High-Resolution H- and K-Band Spectroscopy of HD115617 with Comparative Optical Spectrum Analysis

Sena Aleyna Şentürk, Timur Şahin and Cenk Kayhan

We present the first high-resolution near-infrared spectroscopic analysis of the solar analog HD115617 (61 Virginis), complemented by optical spectroscopy, asteroseismology, and spectral energy distribution modeling. Using ESPRESSO and IGRINS spectra with a newly calibrated NIR line list, we derived atmospheric parameters that revealed notable differences between spectral regions: the optical analysis yielded Teff = 5500 +- 140 K, log g = 4.40 +- 0.16, and solar metallicity, whereas the NIR yielded Teff = 5750 +- 140 K. We tested this 250 K discrepancy using the independent line depth ratio (LDR) method for both spectra. When applied to the optical lines, LDR confirmed the cooler scale (5553 +- 73 K); for the NIR lines, it provided an intermediate temperature (5636 +- 15 K). Asteroseismic scaling with TESS data yielded a radius of 0.98 +- 0.09 R_sun, consistent with SED fitting and confirming the star's main-sequence solar-like status. However, the age estimates diverged between methods, with optical and NIR analyses yielding ages of 10.97 and 8.04 Gyr, respectively. Critically, a condensation temperature analysis revealed no significant trend, confirming the star's bulk solar-like composition and showing no chemical signature of planetary formation processes. Kinematic diagnostics place HD115617 in the thin Galactic disk, with a birth radius of approximately 5.7-8.0 kpc. Although the spectral differences may be linked to the star's multi-planet system or debris disk, our analysis highlights the critical challenge of distinguishing such effects from methodological systematics in multi-wavelength studies. Consequently, we propose a systematic, homogeneous optical-NIR survey of solar-type stars to resolve this ambiguity, which could ultimately inform novel indirect methods for characterizing stellar environments.
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Astrophysics of Galaxies

The apparent Large Magellanic Cloud star cluster age gap

Jonathan H. Klos and Andrés E. Piatti

In the Large Magellanic Cloud (LMC), there have been very few clusters observed with ages between 4 and 11 Gyr. This phenomenon is sometimes referred to as the `LMC age gap'. We constructed a model of the cluster age distribution aimed at reproducing this scenario. We linked the star formation history to the cluster initial mass function via a power-law relation between maximum initial cluster mass and global star formation rate. Using a constant cluster-forming efficiency of 5%, we obtained the cluster formation history. Applying a model of cluster mass loss calibrated using N-body simulations and an observational completeness limit, we computed the observable fraction of initially formed clusters. We were then able to model the cluster age distribution. For a maximum initial cluster mass below $10^5$M$_\odot$ at a star formation rate of 1 M$_\odot$pc$^{-2}$Gyr$^{-1}$, our model reproduced the observed lack of clusters with ages between 4 and 11 Gyr. However, our model required a maximum initial mass at 1 M$_\odot$pc$^{-2}$Gyr$^{-1}$ of at least $2\cdot 10^5$M$_\odot$ in order to reproduce the population of ancient globular clusters. A linear change between maximum initial cluster mass relations from 8 to 12 Gyr reproduced the age gap to a satisfactory extent. In our model, the age gap is a consequence of the star-forming history and current observational limits. The age gap corresponds to a period characterised by a lower star formation rate, whereby no clusters with an initial mass above approximately 2 to 5$\cdot 10^5$M$_\odot$ were formed. In the present day, these clusters have become so faint that only few of them have been detected. The pattern of both young-and-bright and old-and-massive clusters being more easily detectable than clusters of intermediate ages might reflect a more general phenomenon and not necessarily one specific to the LMC.
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High Energy Astrophysical Phenomena

Pulsational mass loss from supermassive stars creates the compact shells of Little Red Dots

Devesh Nandal, Igor Chilingarian, Chris Nagele et al. (+3 more)

Little Red Dots (LRDs) have emerged as one of the central puzzles of the JWST era. Their spectra increasingly require dense gas close to the source, yet the physical origin of that cocoon-like structure remains unclear. We examine whether late pulsational mass loss from supermassive stars (SMS)leads to dense gas cocoons. We analyze five accreting GENEC models at different metallicities with characteristic masses of order $10^5\,M_\odot$, following them through post-accretion evolution with radial pulsation calculations and general relativistic (GR) stability diagnostics. Mass loss during the final stages of evolution occurs not as a steady wind, but through discrete strange-mode ejection episodes. In the $Z=10^{-2}\,Z_\odot$ model, which provides the clearest LRD analogue, four late episodes last $41$–$282$ yr and eject $10$–$348\,M_\odot$ each, for a total loss of $(4.8-10)\times10^2\,M_\odot$; the final episode alone contributes $\simeq 73\%$ of that budget. Since the last episode dominates the mass-loss, it is the only event sufficiently massive enough to leave behind a compact, optically thick shell extending out to 0.4 pc that reproduces the LRD dense gas cocoon. The final ejecta are H/He dominated but chemically distinctive, with a robust nitrogen-rich composition, $\log(\mathrm{N/O})\simeq0.13$ and $\log(\mathrm{C/O})\simeq-0.23$. The SMS reaches GR instability at an age of $\sim 1$ Myr and collapses in $\sim10^4$ s, retaining $\sim 99\%$ all of its mass. Across the full metallicity range from Pop III to $10^{-2}\,Z_\odot$, this shell-ejection channel persists. Pulsational mass-loss from SMSs therefore provides a physically motivated origin for the compact cocoon-like structure implied by LRDs, while remaining the natural progenitors of the massive black hole seeds invoked in direct collapse scenario.
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All authors Devesh Nandal, Igor Chilingarian, Chris Nagele, John Chisholm, Franz E. Bauer, Abraham Loeb

Solar and Stellar Astrophysics

The FUor Mass Distribution Matches the Solar Neighborhood IMF: Evidence for a Universal Eruptive Phase

Adolfo S. Carvalho and Lynne A. Hillenbrand

Eruptive accretion events are expected to play an important role in the mass buildup stage of individual star formation. FU Ori objects (FUors) experience the most extreme eruptive outbursts, which raise the accretion rate of the disk from $10^{-9}-10^{-8} \ M_\odot \ \mathrm{yr}^{-1}$ to $10^{-5}-10^{-4} \ M_\odot \ \mathrm{yr}^{-1}$ and last for decades. During an outburst, the disk is approximately 100 times brighter than the star, making direct study of the central star impossible. However, the disk is expected to be in Keplerian rotation around the star, enabling indirect constraints on properties of the central source via observations of the disk. Using $1-2.4 \ \mu$m high resolution spectra of several tens of FUors, we demonstrate the expected Keplerian rotation in their inner disks. We then adopt a Keplerian rotational broadening profile to model the line profiles of spectral lines, and focussing on the H-band region, we infer the mass distribution of FUors. We finally show that this mass distribution is consistent with inferred Solar neighborhood initial mass functions, suggesting all young stars undergo a period of FUor outbursts in their pre main-sequence evolution.
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Solar and Stellar Astrophysics

The curved jet in the young star FN Tau

M.A. Burlak, A.V. Dodin, A.V. Zharova et al. (+5 more)

In the vicinity of the young star FN Tau, we have detected a microjet and four Herbig-Haro objects, whose positions and kinematics indicate the presence of a bipolar collimated outflow from the star - HH 1267. The stellar jet does not propagate rectilinearly, and we discuss the possibility that the curved shape of the jet, whose axis is inclined to the line of sight at an angle $<20^\circ$, results from the precession of the inner regions of the FN Tau protoplanetary disk. Approximately 60 years ago, the star underwent outbursts with an amplitude of $\Delta m_{\rm pg} \sim 2^{\rm m}$ lasting several months, which we associate with the onset of the microjet.
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All authors M.A. Burlak, A.V. Dodin, A.V. Zharova, N.P. Ikonnikova, V.A. Kiryukhina, S.A. Lamzin, D.A. Lashin, B.S. Safonov

Astrophysics of Galaxies

Prevailing thermally-pulsing-asymptotic-giant branch stars in the near-infrared rest-frame spectra of distant quiescent galaxies: towards robust galaxy ages and masses

Shiying Lu, Emanuele Daddi, Claudia Maraston et al. (+12 more)

We recently reported the discovery of prominent features from the thermally pulsing asymptotic-giant-branch (TP-AGB) phase in the rest-frame near-infrared of a massive quiescent galaxy (QG) at z~1 observed with the JWST, which provides strong constraints on population synthesis (SPS) models. Here we extend this analysis to 27 JWST/NIRSpec PRISM spectra of QGs at z>1 from GO-5019 and CEERS, with signal-to-noise ratios of ~100 (15/27) and ~50 (12/27), respectively. Each spectrum is modeled with three SPS models: the latest Maraston (M13) models with a sizable TP-AGB phase, and widely-used Bruzual & Charlot 2003 (BC03) and Conroy & Gunn 2009 (C09) models, both with weaker TP-AGB contributions. M13 generally provides the best overall fit and the most consistency between the optical and the NIR. Only M13 yields consistent ages from separate fits to the optical, the NIR and the full wavelength ranges. Compared to BC03 and C09, M13 yields systematically younger mass-weighted ages (by <500 Myr) hence lower stellar masses (by <0.2 dex). All models favor super-solar (Z/Z_sun>1.5) metallicities. Signal-to-noise-weighted stacked spectra reveal that TP-AGB-related features are strongest in galaxies with mass-weighted ages of t=0.4-1.8 Gyr, consistent with the predicted peak TP-AGB contribution in M13. Further sample subdivisions show that these features are most pronounced in high-mass, dusty, and metal-rich systems. These results support a significant contribution from TP-AGB stars to the NIR spectra of high-redshift, intermediate-age galaxies and pave the way towards improved spectral population synthesis modeling and robust stellar ages and masses.
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All authors Shiying Lu, Emanuele Daddi, Claudia Maraston, Alvio Renzini, Daniel Thomas, Mark Dickinson, Pablo Arrabal Haro, Luis Gabriel Dahmer-Hahn, Raphael Gobat, Mauro Giavalisco, Ray A. Lucas, Fabio Pacucci, L. Y. Aaron Yung, Michaela Hirschmann, Benne Holwerda

Astrophysics of Galaxies

Resolving the Dust Budget Crisis at $z \sim 8$ with Optically Thick, High-Density Molecular Clumps: MACS0416_Y1

Ryusei R. Kano, Tsutomu T. Takeuchi, Erina R. Kawamoto et al. (+3 more)

Dust plays a crucial role in galaxy evolution by shaping the spectral energy distribution (SED) and star formation history. However, standard models often underestimate the infrared luminosity of high-redshift galaxies ($z \sim 8$), leading to the so-called dust budget crisis. In this work, we modify the theoretical framework by focusing on compact star-forming clumps in the interstellar medium. Motivated by the observed compactness of high-z galaxies, we treat the cold neutral medium density as a free parameter. Our analysis reveals that the ISM must reach extreme densities ($n_{\text{H,CNM}} \sim 7.5 \times 10^3 \, \mathrm{cm}^{-3}$). This enhances UV photon trapping, accelerates dust processing in dense gas, and reduces dust destruction by supernova shocks. Our model successfully reproduces the observed UV-to-FIR SED of MACS0416_Y1 ($z = 8.312$). A grain-size-resolved treatment further shows that the warm IR emission is dominated by intermediate-size grains ($a = 0.01$ - $0.1\,\mu$m), which contribute about 89% of the luminosity near the SED peak and in the ALMA Band~9 continuum. These grains are nearly in thermal equilibrium at characteristic temperatures of $\sim 70$ K, while the largest grains remain cooler and the smallest grains exhibit a high-temperature tail with low probability. We conclude that extreme ISM densities can alleviate the dust budget crisis by promoting efficient UV photon trapping and rapid dust evolution, thereby increasing dust mass and producing a multi-temperature grain population.
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All authors Ryusei R. Kano, Tsutomu T. Takeuchi, Erina R. Kawamoto, Ryosuke S. Asano, Masato Hagimoto, Yoichi Tamura

Cosmology and Nongalactic Astrophysics

Measuring neutrino mass and asymmetry through galaxy pairwise peculiar velocity

Wangzheng Zhang, Ming-chung Chu and Shihong Liao

Cosmic neutrinos are among the most abundant fermions in the Universe, yet the values of their masses and chemical potentials remain uncertain. In this Letter, we present the first constraints on the total neutrino mass $M_\nu$ and the neutrino asymmetry parameter $\eta^2$ derived from the mean galaxy pairwise peculiar velocity in the quasi-linear and nonlinear regimes. We develop a simulation-based analysis pipeline that connects neutrino properties to predictions of galaxy pairwise velocity, and apply it to galaxy data from the Cosmicflows-4 grouped catalog. Our analysis is performed within two independent cosmological frameworks, based on cosmological parameters derived from Cosmic microwave background (CMB) and local distance ladder measurements, respectively. By performing fits to the galaxy pairwise velocity, we obtain consistent constraints from both frameworks. Quoting posterior means with 68% CL, we find $M_\nu = 0.24^{+0.34}_{-0.18}\ \mathrm{eV}$ and $\eta^2 = 2.14^{+0.30}_{-0.32}$ in the CMB framework, and $M_\nu = 0.37^{+0.34}_{-0.26}\ \mathrm{eV}$ and $\eta^2 = 2.4^{+2.1}_{-1.6}$ in the local framework. In particular, we find a 7$\sigma$ measurement of a non-zero neutrino asymmetry in the CMB framework. These neutrino parameters are consistent with those, in our previous work, obtained from the Planck CMB temperature power spectrum. These results demonstrate that galaxy pairwise velocities provide an independent and sensitive probe of neutrino properties, opening a new avenue for testing neutrino physics with large-scale structure observations.
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Solar and Stellar Astrophysics

Neural Simulation-based Inference with Hierarchical Priors for Detached Eclipsing Binaries

Jacqueline Blaum Hough and Joshua S. Bloom

Detached eclipsing binaries (DEBs) enable direct inference of stellar and orbital properties across diverse stellar populations. However, inference typically requires computationally intensive forward modeling and radial velocity (RV) measurements, limiting homogeneous analyses to relatively small samples. The growing number of photometrically identified DEBs from modern time-domain surveys motivates scalable methods for extracting physical parameters without RVs. We present multimodal amortized neural posterior estimation for DEB inference that combines survey-realistic light curves, broadband SEDs, and Gaia parallaxes within a physically motivated hierarchical prior framework. The generative model enforces broad stellar evolution consistency through MIST isochrones and geometric eclipse prior constraints while incorporating empirically derived survey cadence patterns and flux-dependent noise models to produce realistic training data. A conditional normalizing flow, informed by modality-specific encoders, approximates the full 16-dimensional posterior distribution. Across nearly 5000 held-out simulations, the amortized posterior recovers parameters accurately and yields statistically calibrated uncertainties, verified through simulation-based calibration and empirical coverage tests. Parameters tied directly to eclipse geometry and flux scale are tightly constrained, while quantities intrinsically degenerate in broadband photometry (e.g., age and metallicity) exhibit broader posteriors consistent with expectations. Generating the training set requires computational effort similar to a traditional MCMC analysis of only a single system, and posterior inference for new systems is effectively instantaneous. This framework enables scalable, statistically calibrated inference for large DEB samples, providing a pathway toward population-level analysis in the era of large time-domain surveys.
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Earth and Planetary Astrophysics

Stability of Multiplanet Systems Through Hot Jupiter Destruction

Donald Liveoak, Tim Hallatt and Sarah Millholland

Recent observational and theoretical work suggests that the sub-Jovian desert (periods ${\lesssim}3$ days, masses ${\sim}10{-}100 \ M_{\oplus}$) hosts the remains of destroyed hot Jupiters (“desert dwellers"). In this work, we explore how differing hot Jupiter destruction mechanisms – Roche lobe overflow (RLO) vs. tidal disruption during high eccentricity migration (HEM) – may be discerned observationally based on the presence of companion planets to desert dwellers. We show that gas giant destruction via RLO clears out the desert of any companions inside orbital periods ${\lesssim}$4 days; desert dwellers should sit alone in the desert if they form through this mechanism. Numerically mapping the instability threshold in planet mass and orbital distance, we find that the majority of observed companions to desert dwellers are safely in the stability region. RLO therefore does not preclude the existence of nearby companions beyond the desert, in contrast to gas giant tidal disruption during HEM. Further characterization of desert dweller systems may therefore elucidate the fates of hot Jupiters.
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Earth and Planetary Astrophysics

A giant solution to the disk mass budget problem of planet formation

Sofia Savvidou

Understanding how dust evolves in protoplanetary disks is crucial to constraining the initial conditions of planet formation. The apparent "mass budget problem", which stems from the comparison of the observed disk masses to the ones inferred for exoplanets, remains debated, as it is unclear whether the discrepancy arises from limitations in interpreting disk observations, from evolutionary processes that rapidly deplete dust, or from incorrect assumptions about the initial disk mass distribution. This work is build on the analysis presented in Savvidou and Bitsch (2025) by separating the cumulative distribution functions of dust masses at different evolutionary stages into different populations according to the initial disk masses and embryo injection times. The best match to observations comes from disks with intermediate initial disk masses around 4-7% solar mass. The largest discrepancy between the total dust mass in the models and the estimated through an "optically thin" approximation comes from the models that have the most favorable conditions for giant planet formation and thus contain a large fraction of giants and subsequently trapped "optically thick" dust mass because of the pressure bumps they generate. However, the final dust masses remain higher compared to the estimates from the observed evolved disks. Example cases in this work including planetesimal formation show that the pressure bumps that giant planets form can be prime locations for planetesimal formation and the conversion to planetesimals significantly decreases the dust mass, as expected. However, (giant) planet formation is not influenced showing that the mass in evolved protoplanetary disks can be estimated to be quite low but it can be a natural consequence of planetesimal and planet formation along with depletion due to radial drift.
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High Energy Astrophysical Phenomena

Search for Anisotropic Pair Halos Associated with Blazar Jets

Ao Zhang, Wenlei Chen and Manel Errando

The origin of intergalactic magnetic fields (IGMFs) remains one of the key open questions in cosmology. Gamma-ray pair halos produced by electromagnetic cascades from TeV-emitting blazars provide a powerful indirect probe of these fields. In this work, we present a novel search for pair halos that explicitly exploits their expected anisotropic morphology, aligning with the projected orientation of blazar jets on the sky. Using a Monte Carlo framework to model the spatial distribution of cascade emission, we identify an optimal sample of 21 high-synchrotron-peaked BL Lac objects with well-constrained jet position angles from radio interferometry. By rotating and stacking Fermi-LAT observations of these sources along their jet directions, we enhance sensitivity to anisotropic extended emission that would be diluted in traditional orientation-agnostic analyses. Applying a likelihood analysis to the combined dataset, we find evidence for a non-zero IGMF, excluding the null hypothesis at $3.8\sigma$ level and obtaining a best-fit field strength of $B_0 = 2.8 \times 10^{-16}\,\mathrm{G}$, with a $99\%$ confidence interval of $0.9 \times 10^{-16}\,\mathrm{G} < B_0 < 8.9 \times 10^{-16}\,\mathrm{G}$. Our result is consistent with previous constraints from spectral, spatial, and temporal studies, while demonstrating that incorporating anisotropic information provides a significant gain in sensitivity. This approach opens a new avenue for probing intergalactic magnetism and highlights the potential of future high-angular-resolution gamma-ray observations to directly image pair halos and map magnetic fields in cosmic voids.
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High Energy Astrophysical Phenomena

Radio detection of supernova remnant G310.7-5.4 with $\gamma$-ray counterpart: Abeona SNR

Christopher Burger-Scheidlin, Brianna D. Ball, Sanja Lazarević et al. (+10 more)

G310.7-5.4 is a supernova remnant (SNR) candidate identified as a faint shell in the second epoch Molonglo Galactic Plane Survey (MGPS-2), but this has not been followed up with multi-wavelength observations until now. It is an example of an SNR at high Galactic latitude showing spatially coinciding $\gamma$-ray emission. Here, we make the first detailed investigation of the radio emission from the G310.7-5.4 region, aiming to characterise the radio structure, polarisation measurements and the coinciding GeV emission. We used recent radio continuum observations at 943.5 MHz from the EMU and the POSSUM surveys with ASKAP, as well as 16.5 years of Fermi-LAT observations. We furthermore considered the multiwavelength context of the object by investigating observations previously conducted with other instruments, such as infrared and X-ray surveys. We confirm the SNR candidate as a new supernova remnant, dubbed Abeona. We detect the presence of a faint, extended, bilateral radio shell of the size of around 30' diameter and ASKAP radio flux density of $1.5^{+1.5}_{-0.1}$ Jy with no obvious infrared counterparts. With a radio surface brightness of about $2.4^{+2.4}_{-0.1}\times10^{-22}$ W m$^{-2}$ Hz$^{-1}$ sr$^{-1}$, this SNR is one of the faintest radio SNRs known. The northern part of the shell shows linearly polarised radio emission, characteristic of synchrotron emission in SNRs. The physical size of the SNR is estimated to be around $42^{+42}_{-21}$ pc, which would give a distance of around $4.9^{+4.9}_{-2.5}$ kpc. Furthermore, the spatially coincident $\gamma$-ray source 4FGL J1413.9-6705 shows an energy flux of $1.26\pm0.35\times 10^{-6}$ MeV cm$^{-2}$ s$^{-1}$ with a significance of 5.7 $\sigma$ between 100 MeV and 100 GeV. The SNR is also put in context with known high-latitude SNRs with $\gamma$-ray counterparts and compared with their observational properties.
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All authors Christopher Burger-Scheidlin, Brianna D. Ball, Sanja Lazarević, Roland Kothes, Robert Brose, Jonathan Mackey, Miroslav D. Filipović, Zachary J. Smeaton, Andrew M. Hopkins, Denis Leahy, Mehrnoosh Tahani, Jennifer L. West, Tayyaba Zafar

Astrophysics of Galaxies

HI 21-cm absorption in low- and high-excitation radio-loud AGNs at $z<0.5$ from MALS

P. P. Deka, N. Gupta, J-.K. Krogager et al. (+5 more)

We present results from a search of cold neutral gas associated with radio-loud active galactic nuclei (AGNs) at $z < 0.5$ using HI 21-cm absorption measurements from the MeerKAT Absorption Line Survey (MALS). Cross-matching the MALS 1006 MHz and SDSS DR18 catalogs yields 1908 radio sources at $z < 0.5$. Of these, 613 are classified as AGNs using BPT diagnostics and radio luminosity criteria. We further classify 426 AGNs into 327 low-excitation radio galaxies (LERGs) and 99 high-excitation radio galaxies (HERGs). We observe a significant ($>3\sigma$) difference in $k$-corrected $g-r$ color, consistent with LERGs residing in older galaxies with quenched star formation. We searched a radio-bright subsample of 79 LERGs and 20 HERGs ($S_{\mathrm{1.4\,GHz}} > 4$ mJy) for associated HI 21-cm absorption. This spans six decades in radio luminosity ($\log L_{\mathrm{1.4\,GHz}}$ (WHz$^{-1}$) $\sim 21.1-27.0$), probing an order of magnitude fainter than previous targeted HI surveys. We report five new detections (4 LERGs, 1 HERG) at $0.29 < z < 0.47$. The overall detection rate of $3^{+3}_{-2}$% (at a $3\sigma$ threshold of 10.0 kms$^{-1}$) is consistent with sensitivity-matched low-$z$ ($<0.2$) samples, suggesting no significant redshift evolution out to $z \sim 0.5$ or dependence on radio luminosity. Evaluating velocity offset, asymmetry, and width reveals three systems with entirely redshifted absorption and two with predominantly blueshifted absorption. HI profiles in LERGs show diverse asymmetries and velocity offsets exceeding 350 kms$^{-1}$, indicating disturbed cold-gas kinematics likely driven by lobe expansion or jet activity.
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All authors P. P. Deka, N. Gupta, J-.K. Krogager, S. A. Balashev, H.-W. Chen, F. Combes, H.-R. Klöckner, P. Noterdaeme

High Energy Astrophysical Phenomena

Quasi-Periodic Microstructures in Pulsar Emission: Automated Detection and Archival Survey

Amarnath and Yogesh Maan

The study of quasi-period microstructures in pulsars offers valuable insights into the underlying emission mechanism. However, identifying these features through manual inspection of the intensity time series, often containing thousands to millions of pulses, is both laborious and time-consuming. To address this challenge, we have developed a Python-based software, Quasi-periodic MIcrostructure Search Tool (QMIST), to automate the search for quasi-periodic microstructures in radio pulsar time-series data. We provide a detailed description of the algorithms used in QMIST, demonstrate its efficacy using data on pulsars known to exhibit microstructures, and discuss potential future improvements. Using QMIST, we have performed a multi-epoch survey of quasi-periodic microstructures in a sample of 27 pulsars, using observations from the Giant Metrewave Radio Telescope and the Green Bank Telescope, as well as the archival data from the Parkes telescope. In addition to recovering previously reported microstructures from several pulsars, we report, for the first time, detection of quasi-periodic microstructures in three pulsars, B1451-68, B1706-16 and B1845-19. We also estimate the typical period of microstructures in another pulsar, B0540+23, that was known to exhibit microstructures earlier but the periodicity was unknown. Using the periodicity measurements from our survey, and earlier such measurements from the literature, we confirm the near linear relationship between the microstructure periodicity and the rotation period of pulsars, and discuss our results in the context of the emission mechanism of microstructures.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Ultra-High-Energy Tau Neutrinos as Probes of Lorentz Invariance

Vedran Brdar and Samiur R. Mir

Neutrino telescopes have detected astrophysical neutrinos with energies up to ${O}(100)$ PeV. Several current and proposed experiments aim to observe neutrinos at even higher energies, with the goal of detecting cosmogenic neutrinos. This increase in neutrino energy makes tests of Lorentz invariance violation (LIV) particularly appealing, since the effects of higher-dimension LIV operators on neutrino propagation grow rapidly with energy. In this work, we investigate the potential of the upcoming experiments GRAND and POEMMA to probe LIV in the neutrino sector through the detection of ultra-high-energy tau neutrinos. We generate the cosmogenic neutrino flux using SimProp and interface it with a calculation of neutrino flavor transition probabilities in the presence of LIV effects. Deviations from standard flavor transition probabilities manifest as changes in the expected tau neutrino event rates at GRAND and POEMMA. We first consider the case with a single nonzero LIV operator of various dimensions, and find that the projected sensitivities exceed existing limits from lower-energy probes by orders of magnitude. We then explore scenarios with multiple nonzero LIV parameters and show that their interplay can significantly modify the sensitivities compared to the single-parameter case. Overall, we find that upcoming observations of ultra-high-energy tau neutrinos will place some of the most stringent constraints on LIV.
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Astrophysics of Galaxies

The fragmentation properties of massive star-forming regions in 30Dor-10 at 2000 au resolution

A. Traficante, M. J. Jimenez-Donaire, R. Indebetouw et al. (+9 more)

The fragmentation properties of parsec-scales clumps play a fundamental role in shaping the dense gas condensations known as cores, the immediate progenitor of stars. The distribution of core masses, the so-called core mass function, is the precursor of the stellar initial mass function, which governs the distribution of stellar masses and, consequently, the evolution of galaxies. The stellar initial mass function is often described by a typical Salpeter-like slope, although deviations toward more top-heavy distributions have been reported in extreme environments, raising questions about its universality and about the physical connection between the two mass functions. To date, there are no observational constraints on the core mass function and its link to the initial mass function beyond the Milky Way. Here we present a study of the fragmentation properties and the measurement of the core mass function in an external galaxy, focusing on the 30Dor-10 region in the Large Magellanic Cloud, using high resolution observations that probe spatial scales down to 2000 au. Robust statistical analysis demonstrates that the core mass function is consistent with a Salpeter-like slope and suggests that variations in the stellar mass distribution arise from evolutionary processes rather than from initial fragmentation.
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All authors A. Traficante, M. J. Jimenez-Donaire, R. Indebetouw, T. Wong, A. Nucara, R. Klessen, P. Hennebelle, U. Lebreuilly, C. Mininni, S. Molinari, E. Sabbi, J. Soler