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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 20 January

Astrophysics of Galaxies

The Distance to NGC 4258 from Individual Maser Component Tracking

Daniella van der Boom and Doron Kushnir

We present a reanalysis of the water maser system in NGC 4258 to reassess its geometric distance, commonly reported as approximately 7.6 Mpc with percent-level accuracy, a key anchor in extragalactic distance ladder calibrations and recent determinations of the Hubble constant. We introduce a method that relies exclusively on tracking individual maser components, rather than assuming a single averaged trajectory as in previous works, thereby avoiding arbitrary data averaging that can bias interpretations of the disk's geometry and dynamics. This approach requires spatially resolved individual maser components; consequently, the majority of observational epochs were excluded, as they lack sufficient spatial resolution to localize the maser position. We track individual maser components across multiple epochs and introduce an efficient marginalization method over nuisance parameters (angular radius and azimuth of each maser), reducing the number of free parameters from hundreds to 14. Our analysis reveals that the current observational cadence is insufficient to reliably track the individual masers, which our method relies on, given their intrinsic variability. Across a range of maser selections and model configurations, inferred distances span approximately between 6.7 to 8.1 Mpc, demonstrating significant sensitivity to how our method selects individual masers. Even visually and statistically robust fits can differ by several standard deviations, reflecting ambiguity in component identification across sparsely sampled epochs. We evaluate the impact of observational cadence on tracking fidelity and distance precision, and show that high-cadence monitoring is needed for our method to track individual masers and produce a robust anchor for cosmology.
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Earth and Planetary Astrophysics

Decameter-sized Earth Impactors – II: A Bayesian Inference Approach to Meteoroid Ablation Modeling

Ian Chow and Peter G. Brown

Small asteroids and large meteoroids frequently impact the Earth, though their physical and material properties remain poorly understood. When observed as fireballs in Earth's atmosphere, these properties can be inferred from their ablation and fragmentation behavior. The 2022 release of previously classified United States Government (USG) satellite sensor data has provided hundreds of new fireball light curves, allowing for more detailed analysis. Here we present a new Bayesian inference method based on dynamic nested sampling that can robustly estimate these objects' physical parameters from their observed light curves, starting from relatively uninformative, flat priors. We validate our method against seven USG sensor-observed fireballs with independent ground-based observations and demonstrate that our results are consistent with previous estimates. We then apply our technique to $13$ decameter-size Earth impactors to conduct the most detailed population-level study of their structure and material strength to date. We identify three structurally distinct groups within the decameter impactors. The first group are primarily structurally homogeneous, weak objects which catastrophically disrupt below $\sim1.5$ MPa. The second group are heterogeneous objects which progressively fragment starting from $\sim1$ MPa typically up to $\sim3-8$ MPa. The third group are strong aggregates which remain mostly intact until $9-10$ MPa. Our results also suggest that decameter-size asteroids fragment in two distinct phases: an initial phase at $\sim0.04-0.09$ MPa and a second at $\sim1-4$ MPa. While decimeter- to meter-size objects typically lose most of their mass in the initial phase, larger decameter-size objects instead lose most of their mass in the second phase.
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Astrophysics of Galaxies

Hunting the first Cosmic Giants: formation and detectability of Direct Collapse Black Holes around high-redshift quasars

Alessandro Trinca, Alessandro Lupi, Zoltán Haiman et al. (+4 more)

The rapid emergence of supermassive black holes (SMBHs) in the early Universe poses a challenge to current models of black hole growth. One promising formation pathway is the direct collapse black hole (DCBH) scenario, in which gas in pristine, low-metallicity halos forms supermassive (or quasi-) stars leading to massive black holes seeds under specific environmental conditions. In this work, we investigate the potential host environments of DCBHs by coupling a semi-analytic model tracing BH formation and galaxy co-evolution with high-resolution N-body dark matter merger trees. This allows us to trace the population of DCBHs formed during the hierarchical assembly of a $\sim 10^{12} ~\rm M_\odot$ dark matter halo hosting a bright $10^9 ~\rm M_\odot$ quasar at redshift $z \approx 7$. We find that, when accounting for local fluctuations in the UV radiation field within this early cosmic structure, massive BH seeds can form via direct collapse as early as $z \approx 22$. Even under more stringent conditions for heavy seed formation, tens of DCBHs are predicted to emerge within the simulated overdensity down to $z \sim 14$, at which point metal enrichment of the intergalactic medium inhibits further episodes of direct collapse. A significant fraction of the massive black hole population formed at $z > 14$ is expected to survive in satellite galaxies that do not merge with the central halo down to $z \approx 7$. We show that the existence of such a population of ungrown heavy BH seeds can be probed through deep JWST observations targeting regions surrounding bright high-redshift quasars, and we discuss tailored observational strategies to detect and identify these elusive systems.
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All authors Alessandro Trinca, Alessandro Lupi, Zoltán Haiman, Marta Volonteri, Rosa Valiante, Raffaella Schneider, Roberto Decarli

High Energy Astrophysical Phenomena

Mach $>3$ shocks at the tips of both eROSITA bubbles

Uri Keshet and Arka Ghosh

eROSITA substantiated earlier indications that Loop-I is the northern part of an extended bipolar Galactic-bubble structure, but the southern bubble was not established in nonthermal emission and the shock strength was not robustly measured in either bubble. After using eROSITA data to map the bubble edges, we analyzed edge-adjacent radio and $\gamma$-ray data to remove foregrounds, test if the southern bubble can be detected in nonthermal emission, and measure the corresponding high-latitude spectra of both bubbles. Data were stacked parallel to the eROSITA bubble edges traced by an edge detector, in the same method used previously to pick up weak signals in the smaller, nested Fermi bubbles; the detected brightness jumps were then used to measure the spectrum. We detect ($>5\sigma$) both bubble tips in both radio and $\gamma$-rays, and find a radio spectrum corresponding to high, Mach $3$-$5$ shocks. The southern bubble is fainter, by $\sim$an order of magnitude in radio, its edge propagating into a medium roughly half as dense. The results indicate that these eROSITA bubbles are older, evolved counterparts of the Fermi bubbles, arising from an earlier collimated high-energy outburst from the Galactic center.
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Astrophysics of Galaxies

The Little Red Dots Are Direct Collapse Black Holes

Fabio Pacucci, Andrea Ferrara and Dale D. Kocevski

The discovery by JWST of a substantial population of compact "Little Red Dots" (LRDs) presents a major puzzle: their observed spectra defy standard astrophysical interpretations. Here, we show that LRD spectra are naturally reproduced by emission from an accreting Direct Collapse Black Hole (DCBH). Using radiation-hydrodynamic simulations, we follow the growth of the DCBH seed via a dense, compressionally heated, collisionally ionized accretion flow. The model self-consistently reproduces the screen responsible for the observed Balmer absorption, while allowing UV/optical emission to partially escape, along with reprocessed infrared radiation. Crucially, this structure is not a blackbody and requires no stellar contribution: the UV continuum originates entirely from reprocessed DCBH radiation, attenuated only by a small amount of dust with an extinction curve consistent with high-redshift galaxies. This single framework simultaneously explains the key observational puzzles of LRDs: (a) weak X-ray emission, (b) metal and high-ionization lines alongside absent star-formation features, (c) overmassive black holes, (d) compact morphology, (e) abundance and redshift evolution – linking them directly to pristine atomic-cooling halos, (f) long-lived ($>100$ Myr), slowly variable phases driven by radiation pressure. Our findings indicate that JWST is witnessing the widespread formation of heavy black hole seeds in the early Universe.
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Earth and Planetary Astrophysics

Most Hot Jupiters Were Cool Giant Planets for More Than 1 Gyr

Stephen P. Schmidt and Kevin C. Schlaufman

The origin of hot Jupiters is the oldest problem in exoplanet astrophysics. Hot Jupiters formed in situ or via disk migration should be in place just a few Myr after the formation of their host stars. On the other hand, hot Jupiters formed via eccentricity excitation and tidal damping as a result of planet–planet scattering or Kozai-Lidov oscillations may take 1 Gyr or more to arrive at their observed locations. We propose that the relative ages of hot Jupiters inside, near, and outside the bias-corrected peak of the observed hot Jupiter period distribution can be used to distinguish between these possibilities. Though the lack of precise and accurate age inferences for isolated hot Jupiter host stars makes this test difficult to implement, comparisons between the Galactic velocity dispersions of the hot Jupiter subpopulations enable this investigation. To transform relative age offsets into absolute age offsets, we calibrate the monotonically increasing solar neighborhood age–velocity dispersion relation using an all-sky sample of subgiants with precise ages and a metallicity distribution matched to that of hot Jupiter hosts. We find that the inside-peak and near-peak subpopulations are older than the outside-peak subpopulation, with the inside-peak subpopulation slightly older than the near-peak subpopulation. We conclude that at least 40% but not more than 70% of the hot Jupiter population must have formed via a late-time, peak-populating process like high-eccentricity migration that typically occurs more than 1.5 Gyr after system formation.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Gravitational Waves and Primordial Black Holes produced by Dark Meta Stable Vacuum Decay

Haipeng An, Tingyu Li and Chen Yang

Inspired by string theory and cosmological constant problem, it is plausible that the Universe's vacuum structure is characterized by a landscape of metastable vacua. The existence of dark matter and dark energy further suggests that the dark sector may inhabit its own "dark landscape". If the dark vacuum is metastable, bubbles of lower-energy phases can nucleate at an approximately constant rate. Because the Hubble expansion rate is monotonically non-increasing with cosmic time, such nucleation can eventually lead to percolation and completion of a dark-sector phase transition. In this work, we investigate the phenomenological consequences of this transition, focusing on the resulting stochastic gravitational-wave background and the potential formation of primordial black holes. We find that the gravitational wave spectrum peaks at $k_{\mathrm{peak}}=3.1 H_{\mathrm{PT}}$, with an amplitude $\Omega_{\mathrm{GW}}^{\mathrm{peak}}\simeq1.5 \Omega_\gamma(\Delta\rho/\rho_{\mathrm{tot}})^2$. Furthermore, the formation of primordial black holes is suppressed due to $\Delta N_{\mathrm{eff}}$ constraint.
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Solar and Stellar Astrophysics

Chemical evolution of close massive binaries – tidally-enhanced or tidally-suppressed mixing?

Luca Sciarini, Sophie Rosu, Sylvia Ekström et al. (+3 more)

One of the largest source of uncertainties in the predictions of stellar models comes from the internal transport mechanisms. In close massive binaries, previous theoretical studies suggest that tides systematically boost chemical mixing. However, observations do not reveal any clear period-nitrogen enrichment trend, challenging these predictions. In addition, comprehensive examinations of the interplay between tidal interactions, angular momentum and chemicals transport have so far been scarce. We investigate the interplay between tidal interactions and rotational mixing, and the impact of the angular moment transport (AMT) assumptions. We examine whether tidal interactions enhance or suppress chemical mixing by computing grids of genec binary models with various AMT treatments. In order to independently assess the role of tidal interactions, we systematically compute model variations of single stars with identical initial conditions. Our investigations reveal that tides can either enhance or suppress mixing relative to single-star models, and that the outcome is highly sensitive to the AMT assumptions. We identify a key contrast between the two types of computed models: in close systems subject to tides, magnetic models predict that the mixing efficiency is mostly determined by the orbital configuration, whereas in hydrodynamic models it also depends on the assumed initial velocity. As a result, hydro models may display non-monotonic period-enrichment trends, or even period-enrichment correlations. These results highlight the importance of the AMT assumptions in modeling binaries with tidal interactions. The sensitivity of the predictions of hydro models to initial conditions extends the size of the period-enrichment parameter space they cover, allowing them to accommodate for peculiar observed systems, i.e., with mild enrichment at short periods, or high enrichment at longer periods.
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All authors Luca Sciarini, Sophie Rosu, Sylvia Ekström, Maxime Marchand, Patrick Eggenberger, Georges Meynet

Cosmology and Nongalactic Astrophysics

The era of precision cosmology with voids

Sofia Contarini, Giovanni Verza and Alice Pisani

Cosmic voids, the large underdense regions of our Universe, have emerged over the past decade as powerful cosmological laboratories: their simple dynamics, sensitivity to local gravitational effects and cosmic expansion, and ability to span large volumes, make them uniquely suited to test fundamental physics. Fueled by advances in theory, simulations, and observations, void science has matured into a precision tool for constraining the parameters of the standard cosmological model and its possible extensions. In this review, we provide a comprehensive description of the statistical tools developed to characterize voids, the theoretical models that link them to cosmological parameters, and the methodologies used to extract information from survey data. We highlight the growing synergy between void-based observables and other cosmological probes, and showcase the increasingly stringent constraints derived from voids measured from current survey data and expected from future missions. With the advent of the next generation of galaxy surveys, voids are poised to play a central role in the future of cosmology, turning what was once regarded as emptiness into one of the most promising frontiers of fundamental science.
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Cosmology and Nongalactic Astrophysics

Semi-analytical approach to Ly$\alpha$ multiple-scattering in 21-cm signal simulations

Jordan Flitter, Julian B. Muñoz and Andrei Mesinger

A crucial physical quantity in determining the 21-cm signal during cosmic dawn is the inhomogeneous background of Ly$\alpha$ photons originating from the first galaxies. As these photons travel through the intergalactic medium, their scattering cross-section is often approximated as a delta function at resonance due to computational cost. That is, photons with emitted wavelengths between Ly$\alpha$ and Ly$\beta$ are assumed to travel in straight lines until they redshift into the Ly$\alpha$ resonance. However, due to the damping wing in the Ly$\alpha$ cross-section, this approximation fails as the frequency of the photon approaches the resonant frequency, resulting in multiple scatterings events that could be separated by non-negligible distances. Some previous works studied this effect of Ly$\alpha$ multiple scattering by running computationally heavy radiative-transfer simulations. However, robustly interpreting the cosmic 21cm signal requires exploring a large parameter space of astrophysical uncertainties, motivating more computationally-efficient approaches. Here we incorporate Ly$\alpha$ multiple scatterings in the public, semi-numerical simulation 21cmFAST. We employ Monte Carlo simulations to study the trajectories of Ly$\alpha$ photons on different scales. We find that the distance distributions of Ly$\alpha$ photons with respect to the absorption point can be modeled as analytical functions that are governed by a single parameter. Upon implementing the distance distributions in 21cmFAST, we find that the multiple scattering effect is important (about 50% difference in the 21-cm power spectrum) only at high redshifts before the spin temperature is fully coupled to the kinetic temperature. Furthermore, we find that Ly$\alpha$ multiple scattering does not enhance Ly$\alpha$ heating, and that the combined effect is negligible, especially under realistic X-ray heating scenarios.
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Instrumentation and Methods for Astrophysics

One Attempt at Building an Inclusive & Accessible Hybrid Astronomy Conference: FRB 2025

Alice P. Curtin, Reshma Anna-Thomas, Amanda M. Cook et al. (+6 more)

The rapid expansion of the Fast Radio Burst (FRB) field has been accompanied by a simultaneous growth of FRB conferences. While these meetings are essential for interacting with other researchers and establishing collaborations, many remain only accessible to those with substantial travel funding, flexible schedules, or geographical proximity. This introduces barriers that predominantly affect early career researchers (ECRs) and people from under-resourced regions, limiting the growth, diversity, and sustainability of the community. To address these issues, the FRB 2025 conference, held in Montréal in July 2025 with over 200 participants, was designed to prioritize inclusivity and accessibility alongside scientific excellence. In this work, we describe how we implemented these goals, including: organizing committees spearheaded by ECRs, a fully hybrid format including YouTube livestreams, low registration fees, a pedagogical day at the beginning of the conference, local vegetarian catering, and the implementation of flash-talks instead of posters. From a post-conference survey of participants, we were able to assess the effectiveness of our initiatives. Notably, we received very positive feedback from the online participants, which amounted to roughly half of the attendees, especially regarding the livestreams and talk recordings. The pedagogical day was also greatly appreciated. The low registration fees naturally led to challenges, in particular with the audio-visual management, and although areas for improvement were noted, such as poster sessions and support for attendees requiring visas, the conference was generally viewed as a success. Our experience demonstrates that highly accessible, hybrid conferences are possible within modest budgets ($\$20$k CAD), and we outline recommendations for future conferences, both in the FRB field and in other domains.
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All authors Alice P. Curtin, Reshma Anna-Thomas, Amanda M. Cook, Carolina Cruz-Vinaccia, Jason Hessels, Robert Main, Inés Pastor Marazuela, Lauren Rhodes, Vishwangi Shah

Instrumentation and Methods for Astrophysics

Sample-efficient non-Gaussian noise reduction in gravitational wave data via learnable wavelets

Arush Pimpalkar, Digvijay Wadekar, Mark Ho-Yeuk Cheung et al. (+1 more)

We introduce $\texttt{WaveletNet}$, a wavelet-based neural network architecture to identify and reduce non-Gaussian noise in gravitational wave data. Traditionally, convolutional neural networks (CNNs) have been widely used as a flexible machine learning method to mitigate non-Gaussian noise. However, training CNNs requires many data samples, especially when the input data segments are long. Glitches that mimic high-mass black hole signals are empirically known to have a wavelet-like structure. We exploit this property in $\texttt{WaveletNet}$ by using simple neural networks to learn the best family of wavelets to model glitches in the LIGO-Virgo-KAGRA O3 data. Due to its simplicity, our framework is significantly more sample-efficient than CNNs. As a use case, we build upon the $\texttt{TIER}$ method and show how $\texttt{WaveletNet}$ can improve the performance of any search pipeline. We take potential GW candidates from the pipeline, and then downweight the candidates having noisy strain regions in their vicinity. We use our framework in a modular way: we provide an output score which can be added to the pipeline's existing detection statistic score for the candidates. We test our method using candidates from the $\texttt{IAS-HM}$ search pipeline and show that it improves the search sensitive volume by up to 15% for high-mass, asymmetric binaries.
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All authors Arush Pimpalkar, Digvijay Wadekar, Mark Ho-Yeuk Cheung, Emanuele Berti

High Energy Astrophysical Phenomena

A self-consistent explanation of the MeV line in GRB 221009A unveils a dense circum-stellar medium

O. S. Salafia, A. Celotti, E. Sobacchi et al. (+6 more)

GRB~221009A has been the brightest gamma-ray burst (GRB) observed to date, and its afterglow has been characterized with unprecedented detail at TeV energies by LHAASO. Quite puzzlingly, it is also the most energetic GRB known. Among the riddles posed by this mysterious source, however, the sheer energetics are hardly the most intriguing: an unprecedented emission line at around 10 MeV has been uncovered by a detailed spectral analysis of Fermi/GBM data immediately following the brightest peak in the GRB prompt emission and the peak of the TeV afterglow. The temporal evolution of the line properties can be explained as high-latitude emission from a geometrically thin, relativistically expanding shell where annihilation of a large number of electron-positron pairs took place. We show that this interpretation yields stringent constraints on the properties of such shell, that point to a process that happens at radii typical of external shocks. We then demonstrate that the shell could have been the blastwave associated with the GRB precursor, with the line arising after pair loading of such blastwave as it was illuminated by the bright and hard radiation of the GRB. The scenario, which also explains the abrupt initial rise of the LHAASO afterglow, requires the progenitor of the GRB to have been surrounded by a circum-stellar medium (CSM) extending out to a few 10^15 cm, with a density 10^8-10^9 cm-3 reminiscent of those found in Type IIn supernovae. The consequences of such a CSM on the dynamics and emission of the external shock are yet to be fully explored. If future, more detailed work will confirm the compatibility of the GRB 221009A afterglow with our scenario, this will provide a precious clue to the nature of the progenitor of this peculiar GRB, which could also be present in other bursts that feature a long quiescence followed by a bright emission episode with a hard spectrum.
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All authors O. S. Salafia, A. Celotti, E. Sobacchi, L. Nava, G. Oganesyan, G. Ghirlanda, S. Boula, M. E. Ravasio, G. Ghisellini

Earth and Planetary Astrophysics

Using observations of escaping H/He to constrain the atmospheric composition of sub-Neptunes

James G. Rogers, James E. Owen, Ethan Schreyer et al. (+1 more)

The internal composition of sub-Neptunes remains a prominent unresolved question in exoplanetary science. We present a technique to place constraints on envelope mean molecular weight that utilises observations of escaping hydrogen or helium exospheres. This method is based on a simple timescale argument, which states that sub-Neptunes require a sufficiently large hydrogen or helium reservoir to explain on-going escape at their observed rates. This then naturally leads to an upper limit on atmospheric mean molecular weight. We formalise this argument within a Bayesian inference model and apply it to the archetypal sub-Neptunes GJ-436 b, TOI-776 b and TOI-776 c, which have all been observed to be losing significant hydrogen content as well as relatively featureless transit spectra when observed with JWST. Combining constraints from atmospheric escape and transit spectroscopy in the case of TOI-776 c allows us to tentatively rule out the high mean molecular weight scenario, pointing towards a low mean molecular weight atmosphere with high-altitude aerosols muting spectral features in the infra-red. Finally, we reframe our analysis to the hycean candidate K2-18 b, which has also been shown to host a tentative escaping hydrogen exosphere. If such a detection is robust, we infer a hydrogen-rich envelope mass fraction of $\log_{10} f_\text{env} = -1.67\pm0.78$, which is inconsistent with the hycean scenario at the $\sim 4\sigma$ level. This latter result requires further observational follow-up to confirm.
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All authors James G. Rogers, James E. Owen, Ethan Schreyer, James Kirk

Astrophysics of Galaxies

A Quenched and Relatively Isolated Dwarf Galaxy in the Local Volume

Tehreem N. Hai, Kristen B. W. McQuinn, Yao-Yuan Mao et al. (+7 more)

An increasing number of discoveries of isolated and quenched dwarf galaxies are challenging the idea that the present-day local environment of low-mass systems is the main determinant of their quenching. We present new Hubble Space Telescope (HST) data of one such system, the dwarf galaxy Canes Venatici C (CVn C). CVn C is a low-mass (3.4(+4.2-2.6)*10^6 M_sun) galaxy with a Tip of the Red Giant Branch distance of 8.43(+0.47-0.32) Mpc determined from the resolved stars in the HST imaging, which we also use to derive CVn C's structural parameters. CVn C's distance places CVn C in the Local Volume and in an isolated environment with the most tidally influential L* galaxy > 5Rvir away. Additional constraints from the HST color-magnitude diagram, archival Far-Ultraviolet (FUV), and neutral hydrogen (HI) data show that CVn C is quenched, with no evidence of star formation in the last 100 Myr and no detectable gas (MHI < 1.5*10^6 M_sun). Circumstantial evidence suggests that CVn C may have quenched via past interactions with the L* galaxy NGC 4631 (L_K = 10^10.4 L_sun), and was possibly sent on an extreme backsplash orbit by the tidal dissolution of a subhalo group. However, other quenching mechanisms-such as stripping via the cosmic web-cannot be ruled out. CVn C adds to the growing number of quenched dwarf galaxies in under-dense environments, a population that will be critical to defining the mass and environment regimes in which different quenching mechanisms operate.
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All authors Tehreem N. Hai, Kristen B. W. McQuinn, Yao-Yuan Mao, Roger E. Cohen, David Shih, Erik Tollerud, Joseph A. Breneman, Andrew E. Dolphin, Max J. B. Newman, Adam Smercina

Instrumentation and Methods for Astrophysics

Opportunities in AI/ML for the Rubin LSST Dark Energy Science Collaboration

LSST Dark Energy Science Collaboration, Eric Aubourg, Camille Avestruz et al. (+63 more)

The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will produce unprecedented volumes of heterogeneous astronomical data (images, catalogs, and alerts) that challenge traditional analysis pipelines. The LSST Dark Energy Science Collaboration (DESC) aims to derive robust constraints on dark energy and dark matter from these data, requiring methods that are statistically powerful, scalable, and operationally reliable. Artificial intelligence and machine learning (AI/ML) are already embedded across DESC science workflows, from photometric redshifts and transient classification to weak lensing inference and cosmological simulations. Yet their utility for precision cosmology hinges on trustworthy uncertainty quantification, robustness to covariate shift and model misspecification, and reproducible integration within scientific pipelines. This white paper surveys the current landscape of AI/ML across DESC's primary cosmological probes and cross-cutting analyses, revealing that the same core methodologies and fundamental challenges recur across disparate science cases. Since progress on these cross-cutting challenges would benefit multiple probes simultaneously, we identify key methodological research priorities, including Bayesian inference at scale, physics-informed methods, validation frameworks, and active learning for discovery. With an eye on emerging techniques, we also explore the potential of the latest foundation model methodologies and LLM-driven agentic AI systems to reshape DESC workflows, provided their deployment is coupled with rigorous evaluation and governance. Finally, we discuss critical software, computing, data infrastructure, and human capital requirements for the successful deployment of these new methodologies, and consider associated risks and opportunities for broader coordination with external actors.
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All authors LSST Dark Energy Science Collaboration, Eric Aubourg, Camille Avestruz, Matthew R. Becker, Biswajit Biswas, Rahul Biswas, Boris Bolliet, Adam S. Bolton, Clecio R. Bom, Raphaël Bonnet-Guerrini, Alexandre Boucaud, Jean-Eric Campagne, Chihway Chang, Aleksandra Ćiprijanović, Johann Cohen-Tanugi, Michael W. Coughlin, John Franklin Crenshaw, Juan C. Cuevas-Tello, Juan de Vicente, Seth W. Digel, Steven Dillmann, Mariano Javier de León Dominguez Romero, Alex Drlica-Wagner, Sydney Erickson, Alexander T. Gagliano, Christos Georgiou, Aritra Ghosh, Matthew Grayling, Kirill A. Grishin, Alan Heavens, Lindsay R. House, Mustapha Ishak, Wassim Kabalan, Arun Kannawadi, François Lanusse, C. Danielle Leonard, Pierre-François Léget, Michelle Lochner, Yao-Yuan Mao, Peter Melchior, Grant Merz, Martin Millon, Anais Möller, Gautham Narayan, Yuuki Omori, Hiranya Peiris, Laurence Perreault-Levasseur, Andrés A. Plazas Malagón, Nesar Ramachandra, Benjamin Remy, Cécile Roucelle, Jaime Ruiz-Zapatero, Stefan Schuldt, Ignacio Sevilla-Noarbe, Ved G. Shah, Tjitske Starkenburg, Stephen Thorp, Laura Toribio San Cipriano, Tilman Tröster, Roberto Trotta, Padma Venkatraman, Amanda Wasserman, Tim White, Justine Zeghal, Tianqing Zhang, Yuanyuan Zhang

Cosmology and Nongalactic Astrophysics

Decoupling of large-scale, adiabatic inflationary perturbations from enhanced small-scale modes at one-loop

Laura Iacconi, David Mulryne and David Seery

We reconsider back-reaction from large amplitude, short-scale perturbations onto a long wavelength adiabatic mode. In a loop expansion of the long-mode power spectrum, this back-reaction appears first at 1-loop. Due to the separation between the long and short scales, the separate universe method provides a simple and efficient framework for this computation. In this paper, building on our earlier work, we employ a $\delta N$ formula for the long mode, which captures the effect of short scales. We show that back-reaction at 1-loop is due to either (i) non-linearity of the $\delta N$ formula, or (ii) 1-loop corrections to the initial conditions. We argue that contributions of type (ii) cannot themselves be described within the separate universe framework, but their properties can be constrained using soft theorems and a ”multi-point propagator” expansion. When applied to a band of enhanced short-scale perturbations that crossed the horizon during inflation, our result shows that the loop correction decouples from their detailed properties. Furthermore, the back-reaction we obtain is scale-invariant. Its magnitude is model-dependent, but is degenerate with effects from modes that were still sub-horizon at the end of inflation. In this scenario (but not necessarily in all scenarios), we conclude that the effect is not observable.
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Cosmology and Nongalactic Astrophysics

Revisiting the Matter Creation Process: Observational Constraints on Gravitationally Induced Dark Energy and the Hubble Tension

Tiziano Schiavone, Mariaveronica De Angelis, Luis A. Escamilla et al. (+2 more)

The Hubble tension and the unknown origin of dark energy motivate the exploration of alternative mechanisms for late-time cosmic acceleration. We investigate gravitationally induced particle creation (PC) as a non-equilibrium process that can effectively mimic dynamical dark energy. Within the thermodynamic framework of open systems, we adopt an agnostic approach to the extra created component, leaving its equation-of-state parameter $w_E$ free. We consider four phenomenological parametrisations of the PC rate, allowing deviations from the standard cosmological model ($\Lambda$CDM) only at late times ($0<z<3$). The PC models are constrained using a joint analysis of cosmic chronometers, Type Ia supernovae, local $H_0$ measurements, baryon acoustic oscillations, and cosmic microwave background data. The constraints on $w_E$ are consistent with dark energy, while particle creation of pressureless matter is disfavoured. All PC scenarios provide fits comparable to $\Lambda$CDM, with one showing effective dynamical dark-energy behaviour. When early- and late-time datasets are analysed separately, the PC models reduce the Hubble tension to $\simeq 2.4\,\sigma$–$3\,\sigma$, compared to $4.3\,\sigma$ in $\Lambda$CDM. Gravitationally induced dark energy thus offers a consistent late-time extension of $\Lambda$CDM and a viable theoretical framework for dynamical dark energy.
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All authors Tiziano Schiavone, Mariaveronica De Angelis, Luis A. Escamilla, Giovanni Montani, Eleonora Di Valentino

Astrophysics of Galaxies

Probing AGN duty cycle and cluster-driven morphology in a giant episodic radio galaxy

Shobha Kumari, Sabyasachi Pal, Surajit Paul et al. (+1 more)

The evolution of radio jet morphology and its energetics is significantly influenced by the environment in which the host galaxy resides. As giant radio galaxies (GRGs) often extend to the scale of entire galaxy clusters ($\sim$Mpc) and beyond, they are a suitable class of objects for studying jet–intracluster medium interactions. This paper presents a multiwavelength study of a GRG, J1007+3540, using the LOFAR Two-metre Sky Survey second data release (LoTSS DR2) at 144 MHz and the upgraded Giant Metrewave Radio Telescope (uGMRT) at 400 MHz. The source has a projected linear extension of 1.45 Mpc and is hosted by MaxBCG J151.77665+35.67813, within the WHL 100706.4+354041 cluster. At both frequencies, the source exhibits clear signatures of recurrent jet activity, a one-sided, extended, tail-like diffuse structure with a morphological break in the tail. The estimated radiative ages of the inner lobes and outer north lobe are $\sim$140 Myr and $\sim$240 Myr, respectively. In addition to the radio analysis, we performed optical–to–infrared spectral energy distribution modelling. The host galaxy is an evolved elliptical system with a stellar mass of $\log_{10}(M_\star/M_\odot) = 11.0$ and an old stellar population age of $\sim$12 Gyr. The high infrared-derived star formation rate ($\sim106~M_\odot$~yr$^{-1}$) of the source implies significant dust-obscured star formation, potentially linked to merger-driven gas inflows. J1007+3540 presents a rare combination of a restarted jet, a detached tail-like structure, and unusual spectral flattening beyond the tail break, which is very rare to report together in a GRG. This rare and remarkable system offers a unique laboratory for probing the interplay between active galactic nucleus activity, star formation, and environmental effects in cluster-surrounded GRGs.
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All authors Shobha Kumari, Sabyasachi Pal, Surajit Paul, Marek Jamrozy

Solar and Stellar Astrophysics

The [Fe XIII] Infrared 10747 Angstrom and 10798 Angstrom Lines in Novae

D. P. K. Banerjee, C. E. Woodward, A. Evans et al. (+3 more)

The forbidden lines of [Fe XIII] at 10,747 Angstrom and 10,798 Angsrtom are among the most prominent lines in the near-infrared spectrum of the solar corona. They have been used routinely, both outside and during eclipses, as sensitive probes of the electron density and polarization in the solar corona. Many novae pass through a coronal phase, wherein the highly ionized nova ejecta have physical conditions that are remarkably similar to those of the solar corona. Many of the coronal emission lines that are seen are common to the spectra of both the Sun and novae. Yet, it appears that no robust detection of the [Fe XIII] lines has been made in a nova. Here we report the detection of these two infrared [Fe XIII]lines in the spectrum of the recurrent nova V3890 Sgr, taken 23.43 and 31.35 days after its August 2019 outburst. From their line strengths, we derive values of 10^10 per cubic cm and 10^[8.5-9] per cubic cm for the electron density on the two. The decrease in density between epochs can be explained if the density decreased with a power law n ~ r**alpha with a alpha inferred to be -3. The average temperature of the coronal gas is estimated to be T = (2.51\pm0.06) x 10^6~K. We find that recurrent novae with giant secondaries, including T CrB whose eruption is imminent, are the most suitable sources for further detections of the [Fe XIII] lines. epochs.
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All authors D. P. K. Banerjee, C. E. Woodward, A. Evans, T. R. Geballe, V. Joshi, S. Starrfield

Earth and Planetary Astrophysics

The PAIRS project: a global formation model for planets in binaries. II. Gravitational perturbation effects from secondary stars

Arianna Nigioni, Julia Venturini, Emeline Bolmont et al. (+3 more)

Roughly half of Sun-like stars have at least one stellar companion, whereas it is widely assumed that most known exoplanets orbit single stars, largely due to observational biases. However, astrometric surveys, direct imaging, and speckle interferometry are steadily increasing the number of confirmed exoplanets in binaries. A stellar companion introduces additional effects, such as circumstellar disk truncation and gravitational perturbations, which can strongly impact planet formation. While global planet formation models, for example the Bern model, have been broadly applied to single stars, modeling S-type binaries requires key modifications to capture these effects. This study extends the Bern model by incorporating the gravitational influence of a stellar companion into its N-body integrator, allowing us to quantify how this perturbation affects planetary formation and final system architecture across a range of binary configurations. By comparing binary and single-star systems under identical initial conditions, we can assess the specific impact of binary-induced dynamics. We ran three sets of simulations: (i) a grid of in situ single-embryo cases to quantify gravitational effects; (ii) formation simulations with and without migration to compare outcomes with single-star analogs; and (iii) multi-embryo runs to evaluate impacts on multi-planetary systems. Planets forming beyond half the host star's Hill radius are much more likely to become unbound especially in systems with high binary eccentricity. Even within stable zones, growth is suppressed by both reduced material availability and increased eccentricity from stellar perturbations. Both disk truncation and stellar perturbations must be included to model planet formation in S-type binaries accurately. Neglecting either one will end up misrepresenting planetary growth and survival.
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All authors Arianna Nigioni, Julia Venturini, Emeline Bolmont, Diego Turrini, Yann Alibert, Alexandre Emsenhuber

Earth and Planetary Astrophysics

The PAIRS project: a global formation model for planets in binaries. I. Effect of disc truncation on the growth of S-type planets

Julia Venturini, Arianna Nigioni, Maria Paula Ronco et al. (+2 more)

Binary stars are as common as single stars. The number of detected planets orbiting binaries is rapidly increasing thanks to the synergy between transit surveys, Gaia and high-resolution direct imaging campaigns. However, global planet formation models around binary stars are still underdeveloped, which limits the theoretical understanding of planets orbiting binary star systems. Hereby we introduce the PAIRS project, which aims at building a global planet formation model for planets in binaries, and to produce planet populations synthesis to statistically compare theory and observations. In this first paper, we present the adaptation of the circumstellar disc to simulate the formation of S-type planets. The presence of a secondary star tidally truncates and heats the outer part of the circumprimary disc (and vice-versa for the circumsecondary disc), limiting the material to form planets. We implement and quantify this effect for a range of binary parameters by adapting the Bern Model of planet formation in its pebble-based form and for in-situ planet growth. We find that the disc truncation has a strong impact on reducing the pebble supply for core growth, steadily suppressing planet formation for binary separations below 160 au, when considering all the formed planets more massive than Mars. We find as well that S-type planets tend to form close to the central star with respect to the binary separation and disc truncation radius. Our newly developed model will be the basis of future S-type planet population synthesis studies.
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All authors Julia Venturini, Arianna Nigioni, Maria Paula Ronco, Natacha Jungo, Alexandre Emsenhuber

Solar and Stellar Astrophysics

Dynamical mass of a solar-like oscillator at the main-sequence turnoff from Gaia astrometry & ground-based spectroscopy

P. G. Beck, T. Masseron, K. Pavlovski et al. (+11 more)

Asteroseismology is widely used for precise determining of masses of solar-like oscillating stars by performing individual-frequency modeling or applying homological scaling relations. However, these methods lack dynamical validation on the main sequence due to the absence of eclipsing double-lined binary system (SB2) as benchmark objects. By providing the orbital inclination, astrometric binary systems from ESA Gaia DR3 offer an abundant alternative for eclipsing systems. We present KIC693187 as the first SB2, hosting a solar-like oscillating post-main-sequence star with dynamical masses. By combining Gaia astrometry with spectroscopic obtained with the Las Cumbres Observatory network (LCO), we find $M_1^\mathrm{dyn}$=0.99$\pm$0.05$M_\odot$ and $M_2^\mathrm{dyn}$=0.89$\pm$0.04$M_\odot$ for the primary and secondary, respectively. Asteroseismic parameters were extracted from photometry of the NASA \Kepler satellite. The mass from individual frequency modeling is $M_1^\mathrm{IF}$=0.92$\pm$0.01$M_\odot$. Taking into account the systematic uncertainty of 0.04$M_\odot$ for best fit models from individual frequency fitting, we find an agreement within 1.2$\sigma$. From scaling relations we obtain a mass range of 0.93 to 0.98$M_\odot$ by using the observed large frequency separations (\dnu) in the scaling relations for the primary. By using standard corrections for departures from the asymptotic regime of \dnu, we obtained a mass range of 0.83 to 1.03$M_\odot$. The upper ends of both ranges agree well with the dynamical mass of the primary. This approach provides the first empirical validation for main-sequence solar-like oscillators and opens a new window for validating asteroseismology. Through a dedicatded program targeting astrometric SB2 binary systems, ESA's PLATO space mission will provide will enlarge the benchmark sample substantially.
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All authors P. G. Beck, T. Masseron, K. Pavlovski, D. Godoy-Rivera, S. Mathur, D. H. Grossmann, A. Hamy, D. B. Palakkatharappil, E. Panetier, R. A. García, J. Merc, Y. Lu, I. Amestoy, H. J. Deeg

High Energy Astrophysical Phenomena · Cross-listed from nucl-th

Influence of Finite-Nuclei Constraints on High-Density Transitions and Neutron Star Properties

Anagh Venneti, Sarmistha Banik and Bijay K Agrawal

We construct posterior distributions of the equation of state (EoS) for matter beyond the inner crust of neutron stars by incorporating finite nuclei (FN) constraints within relativistic mean field models. These constraints are implemented in three complementary ways: (i) through theoretical bounds on the EoS, (ii) implicitly via nuclear matter parameters, and (iii) explicitly by enforcing consistency with experimental binding energies and charge radii of selected nuclei. The resulting low-density nucleonic EoSs are subsequently matched to a model-agnostic speed-of-sound parametrization, constrained by astrophysical observations, including NICER mass-radius measurements, tidal deformability limits from GW170817, and lower bounds on the maximum neutron-star mass inferred from radio pulsar observations. We find that the admissible range of the transition density is strongly sensitive to the choice of the low-density EoS. In particular, the inclusion of explicit FN constraints significantly reduces the allowed parameter space of the nucleonic EoS at low densities, narrowing the transition-density range by nearly a factor of two. Consequently, neutron-star properties inferred from EoSs with explicit FN constraints differ substantially, with especially pronounced effects for low-mass neutron stars and their correlations with nuclear matter parameters. A quantitative comparison, using metrics based on Mahalanobis distance, shows consistency of the explicit constraints with PSRs J0740+6620, J0030+0451, and J0437-4715, but suggest a possible tension with PSR J0614-3329. These findings underscore the critical importance of a consistent treatment of finite-nuclei properties for reliably inferring the behavior of high-density matter and the presence of possible phase transitions from astrophysical observations.
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Earth and Planetary Astrophysics

Pre-computed aerosol extinction, scattering and asymmetry grids for scalable atmospheric retrievals

Maël M. Voyer and Quentin Changeat

The unprecedented wavelength coverage and sensitivity of the James Webb Space Telescope (JWST) permits to measure the absorption features of a wide range of condensate species from Silicates to Titan tholins. Atmospheric retrievals are uniquely suited to analyse these datasets and characterize the aerosols present in exoplanet atmospheres. However, including the optical properties of condensed particles within retrieval frameworks remains computationally expensive, limiting our ability to fully exploit JWST observations. In this work, we improve the computational efficiency and scaling behavior of aerosol models in atmospheric retrievals, enabling in-depth studies including multiple condensate species within practical time scales. Rather than computing the aerosol Mie coefficients for each sampled model, we pre-compute extinction efficiency (Qext), scattering efficiency (Qscat) and asymmetry parameter (g) grids for seven condensate species relevant in exoplanet atmospheres (Mg2SiO4 amorph sol - gel, MgSiO3 amorph glass, MgSiO3 amorph sol - gel, SiO2 alpha, SiO2 amorph, SiO and Titan tholins). The pre-computed Qext grids significantly reduce computation time between 1.4 and 17 times with negligible differences on the retrieved parameters. They also scale effortlessly with the number of aerosol species while maintaining the accuracy of cloud models. Thereby enabling more complex retrievals as well as broader population studies without increasing the overall error budget. The Qext, Qscat and g grids are freely available on Zenodo as well as a public TauREx plugin -TauREx-PCQ- that utilize them.
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High Energy Astrophysical Phenomena

A multi-wavelength study of the 2025 low state of the intermediate polar BG CMi

A. W. Shaw, K. Mukai, C. O. Heinke et al. (+18 more)

We present multi-wavelength observations of the first recorded low state of the intermediate polar BG CMi. Optical monitoring of the source by members of the American Association of Variable Star Observers reveals a decrease of ~0.5 mag that lasted ~50 d in early 2025. During the low state the optical timing properties imply that BG CMi underwent a change in the accretion mode, as power at the spin frequency $\omega$ dramatically dropped. An XMM-Newton observation revealed a substantial decrease in intrinsic absorption and a slight increase in intrinsic X-ray luminosity, compared to archival Suzaku data. Timing analysis of the X-ray light curves shows that power shifted from the orbital frequency $\Omega$ (prominent in Suzaku data) to $2\Omega$ in the low state XMM-Newton data, along with the strengthening of certain orbital sidebands. We suggest that BG CMi transitioned to disk-overflow accretion, where the white dwarf accreted matter via both a disk and a stream, the latter becoming more dominant during the low state due to a decrease in the mass and size of the disk.
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All authors A. W. Shaw, K. Mukai, C. O. Heinke, C. G. Nixon, D. A. H. Buckley, P. A. Dubovský, F.-J. Hambsch, J. Hilburn, K. Petrík, R. M. Plotkin, S. B. Potter, N. Rawat, T. Shahbaz, S. Dufoer, S. Dvorak, D. Messier, G. Myers, P. Nelson, R. Sabo, J. Ulowetz, T. Vanmunster

High Energy Astrophysical Phenomena

Minutes-long soft X-ray prompt emission from a compact object merger

An Li, Chen-Wei Wang, Niccolò Passaleva et al. (+75 more)

Compact object mergers are multi-messenger sources and known progenitors of some gamma-ray bursts, bright flashes of high-energy radiation powered by a central engine, either an accreting black hole or a neutron star. Our understanding of these events has so far been shaped primarily by observations in the gamma-ray band, leaving their prompt phase poorly constrained at lower energies. A long-lasting ($\approx$100 s) engine-driven X-ray emission was discussed to explain rapidly fading X-ray afterglows following several ($\approx$30%) bursts of short ($\lesssim$2 s) duration. However, this prompt X-ray component was not directly observed and past candidates were not confirmed. Here we report the discovery of EP250704a containing a minutes-long ($\sim$560 s) flash of soft (0.5–4 keV) X-rays immediately following the short ($\sim$0.4 s) GRB 250704B. The variability and spectral shape of this emission are inconsistent with the canonical picture of a hard, accretion-powered spike followed by a standard external-shock afterglow. Instead, the long-soft bump points to a distinct phase of prompt emission in X-rays, which would not have been detected without the soft X-ray coverage of Einstein Probe. The detection of a prompt soft X-ray counterpart in an otherwise ordinary short GRB shows that long-lasting X-ray emission is likely a common feature of merger-driven bursts and a promising electromagnetic counterpart to gravitational wave sources.
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All authors An Li, Chen-Wei Wang, Niccolò Passaleva, Jie An, Bin-Bin Zhang, Eleonora Troja, Yi-Han Iris Yin, Yuan Liu, Shao-Lin Xiong, Li-Ping Xin, Yi-Xuan Shao, Jun Yang, Hui Sun, Dong Xu, Yu-Han Yang, Roberto Ricci, He Gao, Sarah Antier, Rosa L. Becerra, Jia-Xin Cao, Alberto Javier Castro-Tirado, Xin-Lei Chen, Ye-Hao Cheng, Yong Chen, Hua-Qing Cheng, Valerio D'Elia, Massimiliano De Pasquale, Yong-Wei Dong, Eslam Elhosseiny, Rob A. J. Eyles-Ferris, Maria Gritsevich, Xu-Hui Han, Dieter Hartmann, You-Dong Hu, Jing-Wei Hu, Shu-Mei Jia, Nino Kochiashvili, Wei-Hua Lei, Andrew J. Levan, Cheng-Kui Li, Dong-Yue Li, Hua-Li Li, Xiao-Bo Li, Zhi-Xing Ling, He-Yang Liu, Hou-Jun Lv, Daniele B. Malesani, Brendan O'Connor, Hai-Wu Pan, Shashi Bhushan Pandey, Ignacio Perez-Garcia, Daniëlle L. A. Pieterse, Marion Pillas, Yu-Lei Qiu, Andrea Saccardi, Rubén Sánchez-Ramírez, Wen-Jun Tan, Manasanun Tanasan, Nial R. Tanvir, Susanna D. Vergani, Jing Wang, Xiao-Feng Wang, Qin-Yu Wu, Shu-Xu Yi, Tillayev Yusufjon, Chen Zhang, Wen-Da Zhang, Yi-Jia Zhang, Guo-Ying Zhao, Chao Zheng, Shi-Jie Zheng, Chang Zhou, Ping Zhou, Bertrand Cordier, Jian-Yan Wei, Weimin Yuan, Shuang-Nan Zhang, Bing Zhang

High Energy Astrophysical Phenomena

Accretion flow around Kerr metric in the infra-red limit of asymptotically safe gravity

Orhan Donmez, Sushant G. Ghosh, M. Yousaf et al. (+2 more)

We investigate accretion disk dynamics and the formation of quasi-periodic oscillations (QPOs) in the infrared limit around Kerr-like black holes in asymptotically safe gravity. Relativistic hydrodynamic solutions of Bondi-Hoyle-Lyttleton (BHL) accretion reveal that quantum corrections significantly modify the structure of the shock cone formed around the black hole. The black hole spin controls the azimuthal asymmetry of the shock cone through frame-dragging effects, whereas the quantum correction parameter effectively reduces the strength of gravitational focusing by modifying the metric coefficients in the strong-field region, resulting in a wider shock opening angle, weaker post-shock compression, and reduced density concentration within the cone. Time-dependent mass accretion rates reveal oscillation modes trapped within the shock cone. The power spectral density (PSD) investigations suggest that these modes naturally generate low-frequency QPOs, whose amplitudes, coherence, and harmonic structure depend on both the spin and the quantum correction parameter. The PSD analyses performed at different radial locations reveal that identical QPO frequencies are obtained in all cases. The numerically detected frequencies result from the excitation of global oscillation modes trapped within the post-shock region. The resulting global modes are found to consist of fundamental frequencies, their associated harmonic overtones, and near-commensurate frequency ratios such as 2:1 and 3:2. Coherent oscillations are enhanced and near-commensurate frequency ratios are produced when moderate rotation and moderate quantum corrections are coupled. Large quantum correction parameters, on the other hand, wash out unique spectral peaks and suppress oscillation amplitudes.
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All authors Orhan Donmez, Sushant G. Ghosh, M. Yousaf, G. Mustafa, Farruh Atamurotov

High Energy Astrophysical Phenomena

The JEM-EUSO Collaboration: Contributions to the 39th International Cosmic Ray Conference (ICRC2025)

M. Abdullahi, M. Abrate, J.H. Adams Jr. et al. (+164 more)

This is a collection of papers presented by the JEM-EUSO Collaboration at the 39th International Cosmic Ray Conference (ICRC 2025) (Geneva, Switzerland, July 14–24, 2025).
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All authors M. Abdullahi, M. Abrate, J.H. Adams Jr., D. Allard, P. Alldredge, R. Aloisio, R. Ammendola, A. Anastasio, L. Anchordoqui, V. Andreoli, A. Anzalone, E. Arnone, D. Badoni, P. von Ballmoos, B. Baret, D. Barghini, M. Battisti, R. Bellotti, A.A. Belov, M. Bertaina, M. Betts, P. Biermann, F. Bisconti, S. Blin-Bondil, M. Boezio, A.N. Bowaire, I. Buckland, L. Burmistrov, J. Burton-Heibges, F. Cafagna, D. Campana, F. Capel, J. Caraca, R. Caruso, M. Casolino, C. Cassardo, A. Castellina, K. Černý, L. Conti, A.G. Coretti, R. Cremonini, A. Creusot, A. Cummings, S. Davarpanah, C. De Santis, C. de la Taille, A. Di Giovanni, A. Di Salvo, T. Ebisuzaki, J. Eser, F. Fenu, S. Ferrarese, G. Filippatos, W.W. Finch, C. Fornaro, C. Fuglesang, P. Galvez Molina, S. Garbolino, D. Garg, D. Gardiol, G.K. Garipov, A. Golzio, C. Guépin, A. Haungs, T. Heibges, F. Isgrò, R. Iuppa, E.G. Judd, F. Kajino, L. Kupari, S.-W. Kim, P.A. Klimov, I. Kreykenbohm, J.F. Krizmanic, J. Lesrel, F. Liberatori, H.P. Lima, E. M'sihid, D. Mandát, M. Manfrin, A. Marcelli, L. Marcelli, W. Marszał, G. Masciantonio, V.Masone, J.N. Matthews, E. Mayotte, A. Meli, M. Mese, S.S. Meyer, M. Mignone, M. Miller, H. Miyamoto, T. Montaruli, J. Moses, R. Munini, C. Nathan, A. Neronov, R. Nicolaidis, T. Nonaka, M. Mongelli, A. Novikov, F. Nozzoli, T. Ogawa, S. Ogio, H. Ohmori, A.V. Olinto, Y. Onel, G. Osteria, B. Panico, E. Parizot, G. Passeggio, T. Paul, M. Pech, K. Penalo Castillo, F. Perfetto, L. Perrone, C. Petta, P. Picozza, L.W. Piotrowski, Z. Plebaniak, G. Prévôt, M. Przybylak, H. Qureshi, E. Reali, M.H. Reno, F. Reynaud, E. Ricci, M. Ricci, A. Rivetti, G. Saccà, R.E. Saraev, H. Sagawa, O. Saprykin, F. Sarazin, R.E. Saraev, P. Schovánek, V. Scotti, S.A. Sharakin, V. Scherini, H. Schieler, K. Shinozaki, F. Schröder, A. Sotgiu, R. Sparvoli, B. Stillwell, J. Szabelski, M. Takeda, Y. Takizawa, S.B. Thomas, R.A. Torres Saavedra, R. Triggiani, D.A. Trofimov, M. Unger, T.M. Venters, M. Venugopal, C. Vigorito, M. Vrábel, S. Wada, D. Washington, A. Weindl, L. Wiencke, J. Wilms, S. Wissel, I.V. Yashin, M.Yu. Zotov, P. Zuccon

Earth and Planetary Astrophysics

RV$\times$TESS I: Modeling Asteroseismic Signals with Simultaneous Photometry and RVs

Jiaxin Tang, Sharon X. Wang, Yaguang Li et al. (+22 more)

Detecting small planets via the radial velocity method remains challenged by signals induced by stellar variability, versus the effects of the planet(s). Here, we explore using Gaussian Process (GP) regression with Transiting Exoplanet Survey Satellite (TESS) photometry in modeling radial velocities (RVs) to help to mitigate stellar jitter from oscillations and granulation for exoplanet detection. We applied GP regression to simultaneous TESS photometric and RV data of HD 5562, a G-type subgiant ($M_\star=1.09M_{\odot}$, $R_\star=1.88R_{\odot}$) with a V magnitude of 7.17, using photometry to inform the priors for RV fitting. The RV data is obtained by the Magellan Planet Finder Spectrograph (PFS). The photometry-informed GP regression reduced the RV scatter of HD~5562 from 2.03 to 0.51 m/s. We performed injection and recovery tests to evaluate the potential of GPs for discovering small exoplanets around evolved stars, which demonstrate that the GP provides comparable noise reduction to the binning method. We also found that the necessity of photometric data depends on the quality of the RV dataset. For long baseline and high-cadence RV observations, GP regression can effectively mitigate stellar jitter without photometric data. However, for intermittent RV observations, incorporating photometric data improves GP fitting and enhances detection capabilities.
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All authors Jiaxin Tang, Sharon X. Wang, Yaguang Li, Timothy R. Bedding, Guang-Yao Xiao, Fabo Feng, Jie Yu, Zun Wang, Jennifer A. Burt, R. Paul Butler, Brad Carter, Jeffrey D. Crane, Matías R. Díaz, Samuel K. Grunblatt, Daniel Huber, Hugh R.A. Jones, Stephen R. Kane, Jacob K. Luhn, Stephen A. Shectman, Johanna Teske, Rob Wittenmyer, Jason T. Wright, Jeremy Bailey, Simon J. O'Toole, Chris G. Tinney