Peer Revenue Publish or profit

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 24 February

Astrophysics of Galaxies

ALMA Central Molecular Zone Exploration Survey (ACES)-IV. Data of the two intermediate-width spectral windows

Xing Lu, Daniel L. Walker, Adam Ginsburg et al. (+61 more)

We release the intermediate-width spectral window data from the ALMA Central Molecular Zone Exploration Survey (ACES) Large Program, which covers SiO(2-1), SO(2_2-1_1), H13CO+(1-0), H13CN(1-0), HN13C(1-0), and HC15N (1-0), among other molecular line transitions, with an angular resolution of ~2 arcsec and a velocity resolution of 1.7 km s-1 . The full cubes of the two spectral windows as well as the key data products will be available to the community. We also present the integrated brightness, peak brightness, centroid velocity, and Galactic longitude-velocity maps of the six lines. We briefly discuss morphological correlations between the continuum and the molecular line emission, and brightness ratios between pairs of isotopologue or isotopomer lines. We highlight features and trends in the data that will be followed up in upcoming ACES science papers.
Read the full abstract

All authors Xing Lu, Daniel L. Walker, Adam Ginsburg, Ashley T. Barnes, Pei-Ying Hsieh, Alvaro Sanchez-Monge, Savannah R. Gramze, Nazar Budaiev, Marc W. Pound, Jaime E. Pineda, Alyssa Bulatek, Claire Cook, Jonathan D. Henshaw, Katharina Immer, Namitha Issac, Desmond Jeff, Fu-Heng Liang, Steven N. Longmore, Elisabeth A. C. Mills, Sergio Martin, Xing Pan, Qizhou Zhang, John Bally, Cara Battersby, Laura Colzi, Paul T. P. Ho, Izaskun Jimenez-Serra, J. M. Diederik Kruijssen, Maya A. Petkova, Mattia C. Sormani, Robin G. Tress, Jennifer Wallace, J. Armijos-Abendano, Lucia Armillotta, N. Bijas, Rojita Buddhacharya, Laura A. Busch, Natalie O. Butterfield, Melanie Chevance, Ana Karla Diaz-Rodriguez, Christoph Federrath, Ruben Fedriani, Pablo Garcia, Qi-Lao Gu, H Perry Hatchfield, Rebecca J. Houghton, Yue Hu, Janik Karoly, Ralf S. Klessen, Mark R. Krumholz, Xunchuan Liu, Farideh Mazoochi, Francisco Nogueras-Lara, Dylan Pare, Denise Riquelme-Vasquez, Victor M. Rivilla, Miriam G. Santa-Maria, Anika Schmiedeke, Yoshiaki Sofue, Volker Tolls, Q. Daniel Wang, Gwenllian M. Williams, Fengwei Xu, Suinan Zhang

2602.20445 · 24 Feb · Accepted to MNRAS. High-resolution figures will be available in the journal paper. Website is https://sites.google.com/view/aces-cmz/home and data release is linked from there. Pipeline code is at https://github.com/ACES-CMZ/reduction_ACES/releases/tag/2026-02-18

Abstract PDF $GALAC ×1

Astrophysics of Galaxies

Chandra X-ray Observations of Quasars with Velocity-Offset Broad Lines: Assessing the Binary Supermassive Black Hole Hypothesis

Peter Breiding, Michael Eracleous, Tamara Bogdanović et al. (+2 more)

During the final stages of a galaxy merger, dynamical friction acting on the supermassive black holes (SMBHs) in the post-merger remnant can lead to the formation of a gravitationally bound binary SMBH. In the event that at least one of these SMBHs is actively accreting, the system can appear phenomenologically as an active galactic nucleus (AGN) with a broad line region (BLR) kinematically offset from the host galaxy rest frame. Such velocity offsets have been interpreted as signatures of binary SMBHs, recoiling SMBHs, or BLR gas dynamics within a single-SMBH system. We present deep Chandra X-ray observations of five nearby (0.1 < z < 0.2) Sloan Digital Sky Survey quasars whose broad emission lines are Doppler-shifted relative to their host galaxies' systemic velocities, along with archival Chandra observations of 11 additional sources from the same sample. Using our Chandra data, we constrain SMBH masses with multiple independent techniques. We find systematic, method-dependent differences among black hole mass estimates, with masses inferred from the fundamental plane of black hole activity generally lower and single-epoch virial masses typically higher than those obtained using other methods. We also compare the X-ray photon indices and optical-to-X-ray spectral indices of our quasars to the broader quasar population. While we find no strong differences in optical-to-X-ray spectral indices, we do find systematically harder X-ray photon indices than typically observed in comparable quasars. These results constrain competing physical models but do not provide conclusive evidence for or against a binary SMBH origin of the velocity-offset BLRs.
Read the full abstract

All authors Peter Breiding, Michael Eracleous, Tamara Bogdanović, Sarah Burke-Spolaor, T. Joseph W. Lazio

Cosmology and Nongalactic Astrophysics

IR-Safe and IR-Resummed Bispectra Before and After Reconstruction in Unified Lagrangian Perturbation Theory

Naonori Sugiyama

We develop a unified analytic framework for modeling the real-space dark matter bispectrum, including both auto and cross bispectra constructed from pre- and post-reconstruction density fields, based on Unified Lagrangian Perturbation Theory (ULPT). ULPT reorganizes the standard Lagrangian approach by separating the Jacobian deviation, which generates the nonlinear source bispectrum, from the displacement-mapping effect that determines how long-wavelength bulk flows distort observed configurations. Within this structure, we derive general one-loop ULPT expressions for the bispectrum and analyze their infrared (IR) behavior, demonstrating exact, nonperturbative IR cancellation and the natural emergence of an IR-resummed description of baryon acoustic oscillation (BAO) damping. In particular, ULPT enables a detailed and fully analytic treatment of the wiggle-wiggle contribution to the IR-resummed bispectrum, whose structure has remained comparatively unexplored in previous approaches. We further construct IR-resummed models for the cross bispectra of all pre- and post-reconstruction combinations. For configurations in which the displacement fields differ, ULPT captures not only the overall exponential damping but also the more intricate BAO-scale modulation characteristic of mixed pre/post bispectra. Our results clarify the physical origin of nonlinear BAO suppression and provide a compact theoretical framework in which the full ULPT bispectrum, once implemented numerically through displacement-mapping convolution integrals, will automatically encode all nonlinear BAO and IR effects. The framework developed here therefore offers a unified and IR-safe foundation for interpreting next-generation bispectrum measurements.
Read the full abstract

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

Thermodynamic Gravity with Non-Extensive Horizon Entropy and Topological Calibration

Marco Figliolia, Petr Jizba and Gaetano Lambiase

We revisit Jacobson's thermodynamic derivation of gravity for generalized, non-extensive horizon entropies and develop a consistent framework in which modified gravitational dynamics emerge from horizon thermodynamics. By interpreting $S(A)$ as a coarse-grained entropy entering the thermodynamic constitutive relation, we show that only its local slope at a reference area $A_*$ contributes to macroscopic dynamics within a local Rindler-wedge construction. In this setting, the Clausius relation is reformulated as a stationarity condition for a Massieu functional at fixed Unruh temperature, allowing the entropy slope $s_0=(dS/dA)|_{A_*}$ to be identified as the parameter controlling the effective gravitational coupling. For entropy linear in area, Einstein's equations are recovered with $G_{\mathrm{eff}}=1/(4s_0)$. As a separate consistency check, we demonstrate that a scalar-response extension of the horizon entropy density, supplemented by internal entropy production, correctly reproduces the field equations of $f(R)$ gravity. Motivated by group-entropic arguments and generalized thermodynamics, we adopt a power-law entropy $S(A)=\eta(A/4G)^{\delta}$ and study its implications across scales. To remove the ambiguity in the coarse-graining scale, we introduce a Topological Calibration Principle linking the reference area to intrinsic geometric data through the Gauss-Bonnet theorem. For compact cross-sections admitted by the chosen theory or boundary conditions, this yields a topology-dependent effective coupling governed by the Euler characteristic. Consistency requirements constrain deviations from extensivity and generate scale-dependent modifications with potentially observable cosmological signatures. The resulting framework provides a systematic setting for testing non-extensive horizon thermodynamics and its phenomenological implications.
Read the full abstract

Monday 23 February

Astrophysics of Galaxies

Highly Efficient Selection of High-Redshift Emission-Line Galaxies for future DESI-like surveys with Deep Multi-band Imaging

Yoquelbin Salcedo Hernandez, Jeffrey A. Newman, Brett. H. Andrews et al. (+53 more)

Emission-line galaxies (ELGs) are an important tracer of baryon acoustic oscillations (BAO) and large-scale structure (LSS) at $z > 1$. In this work, we investigate the feasibility of using deep wide-area multi-band imaging (e.g., from the Rubin Observatory) to efficiently select high redshift ELGs. Using Hyper Supreme-Cam $grizy$ photometry and COSMOS2020 many-band photometric redshifts, we designed simple color cuts guided by a probabilistic random forest classifier to select galaxies at $z = 1.1$–$1.6$. We then empirically tested and refined these color cuts using two samples of galaxies with deep spectroscopy and broad color coverage obtained with the Dark Energy Spectroscopic Instrument (DESI). Compared to DESI ELGs at $z = 1.1$–$1.6$, we achieve a higher redshift measurement success rate (89% versus 69%), a much higher correct redshift range success rate (84% versus 34%), and a far higher net surface density yield (1372 $\mathrm{deg^{-2}}$ versus 660 $\mathrm{deg^{-2}}$). Combining our sample with current DESI ELGs would increase the net ELG number density by a factor of $\sim3$, moving it out of the shot-noise limited regime and reducing the uncertainties on the BAO scale parameter at $z = 1.1$–$1.6$ by a factor of $\sim 2$.
Read the full abstract

All authors Yoquelbin Salcedo Hernandez, Jeffrey A. Newman, Brett. H. Andrews, Biprateep Dey, Rongpu. Zhou, Noah Sailer, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, R. Canning, F. J. Castander, E. Chaussidon, T. Claybaugh, A. Cuceu, A. de la Macorra, Arjun Dey, P. Doel, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, H. K. Herrera-Alcantar, R. Joyce, S. Juneau, R. Kehoe, D. Kirkby, T. Kisner, A. Kremin, O. Lahav, C. Lamman, M. Landriau, M. E. Levi, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, A. Raichoor, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, C. Yèche, H. Zou

Solar and Stellar Astrophysics

Stellar flare study of nearby young moving group members with TESS Data

Andrew Tran and Inseok Song

We analyze TESS data to explore stellar flares and rotational characteristics in members of Nearby Young Moving Groups (NYMGs). Our study focuses on 417 members of NYMGs aged 10-150 Myr. Using detrended light curves from the TESS Science Office Quick-Look Pipeline, coupled with our own additional detrending scheme for fast rotators, we systematically detect and characterize 6,288 stellar flares from 27,416 flare candidates. We analyzed light curves from Cycles 1-4 of the TESS mission, finding that for each NYMG member analyzed, at least one stellar flare was present. Flare candidates are initially detected using the AltaiPony flare package, followed by a recovery flare amplitudes, durations, and local continuum background levels. We examine the relationship between flare energy, age, and mass, finding a reduced flaring rate for late-type stars with age for high energy flares, as well as 5.5 times more flares detected in the 10-minute cadence TESS data compared to 30-minute cadence data. Additionally, flare events with extreme energies (E >= 10^{34} erg) on M-dwarf and solar-type stars, providing implications for further exploration into exoplanet habitability.
Read the full abstract

Astrophysics of Galaxies

Constraining the Sub-Galactic Relationship Between Star Formation and the Hot Interstellar Medium in NGC 4254

Erik B. Monson, Bret D. Lehmer, Amirnezam Amiri et al. (+17 more)

We investigate the relationship between star formation and X-ray emission from the hot interstellar medium (ISM) on $\sim$kpc scales in NGC 4254 (M99) by combining spatially resolved star formation histories (SFHs) and Bayesian X-ray spectral fitting. We measure sub-galactic star formation rates (SFR) by modeling spectrophotometric UV-IR data with flexible SFHs, and we produce point-source-subtracted maps of the diffuse X-ray emission using Chandra data. We extract and fit the spectra of 5 regions selected by their SFR density $\Sigma_{\rm SFR}$, deriving hot gas luminosities and plasma temperatures. We examine the sub-galactic $kT-\Sigma_{\rm SFR}$ and $L^{\rm gas}_X-\Sigma_{\rm SFR}$ scaling relations in NGC 4254, and compare to predictions from simple models of the feedback into the ISM from core collapse supernovae (CCSNe). The hot gas emission from NGC 4254 is consistent with thermalization of $\approx 40-50\%$ of the energy from CCSNe in the ISM, and mass-loading of the CCSNe ejecta which decreases as $\Sigma_{\rm SFR}^{-1/3}$. Our optimized model implies a temperature and X-ray production efficiency that scale as $kT = (0.72^{+0.26}_{-0.18}~{\rm keV}) \Sigma_{\rm SFR}^{0.34\pm0.10}$ and $\eta = (0.03^{+0.02}_{-0.01}) \Sigma_{\rm SFR}^{0.34\pm0.18}$, respectively, for $\Sigma_{\rm SFR} = 0.01-0.13~{\rm M_{\odot}~yr^{-1}~kpc^{-2}}$. We also compare the properties of the hot ISM to other ISM phases using data from the PHANGS program. The diffuse X-ray emission of a given region is on average 200 times fainter than the H$\alpha$ emission, and we see evidence that the hot ISM is over-pressurized compared to the large-scale dynamical equilibrium pressure of the galaxy, consistent with expansion of the hot ISM into the ambient medium.
Read the full abstract

All authors Erik B. Monson, Bret D. Lehmer, Amirnezam Amiri, Karina Barboza, Ashley Barnes, Antara R. Basu-Zych, Daniel A. Dale, Sanskriti Das, Simthembile Dlamini, Simon C. O. Glover, Kathryn Kreckel, Laura A. Lopez, Sebastian Lopez, Smita Mathur, Hsi-An Pan, Jennifer A. Rodriguez, Karin M. Sandstrom, Sumit K. Sarbadhicary, Jiayi Sun, Thomas G. Williams

Astrophysics of Galaxies

Spatially-resolved interstellar dust properties in the face-on spiral galaxy M 99 as observed by NIKA2

L. Pantoni, F. Galliano, S. C. Madden et al. (+62 more)

Large dust grains in thermal equilibrium dominate the far-infrared and contribute to the millimetre continuum of star-forming galaxies, but constraining their properties is difficult due to free-free and synchrotron contamination. We study spatial variations in the dust spectral index, mass, and grain properties in the nearby face-on spiral galaxy M 99. We use new 1.15 and 2 mm continuum observations from NIKA2 on the IRAM 30 m telescope (IMEGIN Guaranteed Time Large Programme) combined with multiwavelength data from UV to radio. The infrared-to-radio SED is decomposed into dust, free-free, and synchrotron components using the hierarchical Bayesian code HerBIE. Dust is modelled via a modified blackbody (MBB) with variable millimetre spectral index beta and the THEMIS dust model with fixed beta. We perform spatially-resolved analysis at scales ~1.75 kpc (~25”), covering the centre, spiral arms, and inter-arm regions. MBB fits reveal beta variations from ~1.6-1.7 in diffuse regions to ~2.3-2.5 in dense star-forming areas, likely due to grain coagulation and changes in silicate-to-carbonaceous ratios. Dust masses from variable beta are up to ~4x higher than fixed-beta models, which systematically bias dust-to-stellar and dust-to-gas ratios. The small grain fraction rises from ~10% in the centre to ~15% in the diffuse disc, anti-correlated with the interstellar radiation field; gas-phase metallicity plays a minor role within 8 kpc. Synchrotron spectral index ranges from ~0.6-0.7 in star-forming regions to ~1.2 in the diffuse medium, consistent with cosmic-ray electron ageing.
Read the full abstract

All authors L. Pantoni, F. Galliano, S. C. Madden, R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel, M. Baes, A. Beelen, A. Benoît, S. Berta, L. Bing, O. Bourrion, M. Calvo, V. Casasola, A. Catalano, I-D. Chang, I. De Looze, M. De Petris, F.-X. Désert, S. Doyle, E. F. C. Driessen, G. Ejlali, A. Gomez, J. Goupy, A. P. Jones, C. Hanser, A. Hughes, S. Katsioli, F. Kéruzoré, E. W. Koch, C. Kramer, B. Ladjelate, G. Lagache, S. Leclercq, J.-F. Lestrade, J. F. Macías-Pérez, A. Maury, P. Mauskopf, F. Mayet, A. Monfardini, A. Moyer-Anin, M. Muñoz-Echeverría, A. Nersesian, D. Paradis, L. Perotto, G. Pisano, N. Ponthieu, V. Revéret, A. J. Rigby, A. Ritacco, C. Romero, H. Roussel, F. Ruppin, K. Schuster, A. Sievers, M. W. L. Smith, F. S. Tabatabaei, J. Tedros, C. Tucker, N. Ysard, E. M. Xilouris, R. Zylka

Astrophysics of Galaxies

Glance: A Comprehensive Framework for Galactic Archaeology

Iris Breda, Glenn van de Ven, Sabine Thater et al. (+8 more)

A central topic in extragalactic astronomy is understanding the formation and evolutionary histories of galaxies. These systems often comprise multiple structural components with distinct physical and dynamical properties, making it challenging to disentangle their individual contributions. Aiming at investigating the true structure of the inner stellar disk, we have developed a comprehensive pipeline for the chronochemical and dynamical analysis of galaxies (Glance: Galactic archaeoLogy via chronochemicAl & dyNamiCal modElling). The presented pipeline employs several state-of-the-art techniques by integrating them into a single, automated pipeline, enabling streamlined analysis of integral-field spectroscopy data, by allowing users to easily and directly extract valuable information on stellar populations, kinematics, dynamics, and gas properties. It automates multiple analysis techniques, including stellar population synthesis (Fado, Starlight, post-processing with RemoveYoung, kinematic extraction (pPXF, Bayes-LOSVD), and dynamical modelling (Dynamite). It handles tasks such as Galactic extinction correction, de-redshifting, Voronoi binning, and nebular continuum correction, while offering extensive customization options. Parallel processing significantly reduces computational time. When applied to MUSE data sampling the central region of NGC 1566, this methodology reveals that its stellar disk significantly deviates from the conventional exponential model, challenging the assumption of universality in disk morphology. In summary, this work presents a powerful, publicly available pipeline for conducting galactic archaeology, designed to advance our understanding of the formation and evolution of galaxies.
Read the full abstract

All authors Iris Breda, Glenn van de Ven, Sabine Thater, Federica Mauro, Stergios Amarantidis, J. Falcón-Barroso, Prashin Jethwa, Anja Feldmeier-Krause, Masato Onodera, Gerhard Hensler, Gauri Sharma

Earth and Planetary Astrophysics

A Census Before Rubin of Asteroid Families in the Main Belt

David Nesvorny

A collisional family is a collection of >km-size asteroid fragments produced by a large scale collision between asteroids. Here we cataloged 335 notable collisional families in the main asteroid belt. When possible, we estimated each family's formation age, mean visible albedo, taxonomic type, and parent body size. We found that older families (t_age>10 Myr) produced by impacts on small parent bodies (diameter D<5 km) are rarely identified because small members of these families have drifted over time by the Yarkovsky effect and blended with the background. The young families (t_age<10 Myr) typically have small parent bodies (D<10 km) as large asteroids do not disrupt often enough. The full catalog, including membership files for 335 individual asteroid families, is available for download (https://www.boulder.swri.edu/~davidn/Proper25).
Read the full abstract

Astrophysics of Galaxies

First Observation of CO$_2$ Emission and foreground absorption Toward the Galactic Center with JWST

J. Qiu, A. Ciurlo, M. R. Morris et al. (+11 more)

CO$_2$ is an important, stable, and abundant molecule in the Universe, but it is very difficult to detect because it has no observable pure rotational transitions. The unique sensitivity and resolution of the James Webb Space Telescope (JWST) provide a fresh way to investigate it. CO$_2$ is typically found in the solid phase (ice) on grain mantles in dense molecular clouds, but is less commonly detected in the gas phase (compared to common molecules such as CO and H$_2$O) and has mostly been found in protostellar and proto-planetary environments. Here, we report and characterize the first observations of gas-phase CO$_2$ absorption toward two IR-bright regions of the Galactic Center, thanks to the high sensitivity of JWST. Using an LTE model we find a CO$_2$ gas excitation temperature between 20 and 50~K, a column density around 2$\times$10$^{15}$~cm$^{-2}$ and a radial velocity consistent with 0. We also report: 1) simultaneous detections of C$_2$H$_2$ and HCN absorption bands (near 13.7 and 14.0 $\mu$m, respectively), with column densitiy ratios of 1:3 and 3:2 with respect to gas-phase CO$_2$, and 2) CO$_2$ ice absorption with a ice-to-gas ratio of 90, consistent with previous findings. We conclude that the absorbing medium is likely in the foreground, most likely from one or more somewhat clumpy cloud(s), located between 0.15 and 4~kpc away from Earth. Additionally, we detected point-like CO$_2$ emission likely associated with a Galactic Center star (IRS~11SW), which is also spatially coincident with a previously reported X-ray source, raising the possibility that the system is a symbiotic binary.
Read the full abstract

All authors J. Qiu, A. Ciurlo, M. R. Morris, P. Vermot, J. L. Bourlot, D. Rouan, A. Togi, T. Do, A. M. Ghez, E. Bron, F. L. Petit, Y. Clénet, E. A.C. Mills, J. R. Lu

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

Complex Inflaton Potentials with Nonminimal Coupling: Robust Inflation and Geometric Reheating

S. D. Campos

We investigate an inflationary scenario driven by a complex scalar field nonminimally coupled to gravity and subject to a non-symmetric complex potential. The real part of the potential controls the cosmological background and realizes a plateau-type inflation compatible with $\alpha$-attractor $\mathrm{T}$-models, while the imaginary part acts as an effective non-Hermitian deformation encoding dissipative effects. Working in the Jordan frame and imposing ghost-free conditions on the effective Planck mass, we derive the background equations and define a complex equation-of-state parameter whose real part governs the expansion and whose imaginary part quantifies departures from conservative dynamics. Numerical integration shows that the duration of inflation is primarily controlled by the nonminimal coupling $\zeta$, whereas the complex asymmetry parameter $\Delta\varepsilon$ has a negligible impact on the real background: the real energy density and pressure vary by less than $10^{-5}$ as $\Delta\varepsilon$ is scanned over its allowed range. Mapping the two-field dynamics to an effective single-field description in the Einstein frame, we obtain a spectral index $n_s\simeq 0.968-0.971$ and a tensor-to-scalar ratio $r<10^{-3}$, fully consistent with Planck 2018 bounds. We introduce a relevance parameter and show that non-Hermitian effects remain strongly suppressed during slow roll but grow to $\mathcal{O}(1)$ near the end of inflation, triggering an efficient reheating phase without additional fields or ad hoc friction terms. In this sense, the imaginary sector behaves as an effective $\mathcal{PT}$-symmetric channel for energy transfer, providing a geometrical mechanism for inflation and its exit within a non-Hermitian scalar-tensor framework.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Cosmological Constraints on Neutrino Masses in Quintessential Inflation

Jamerson Rodrigues, Gabriel Rodrigues, Felipe B. M. dos Santos et al. (+2 more)

Quintessential inflation provides a unified description of the early and late accelerated phases of the Universe, linking the inflationary epoch to the present-day dark energy-dominated era through a single scalar degree of freedom. In this work, we explore the implications of this unification for cosmological constraints on the sum of neutrino masses. Focusing on the $\alpha$-attractor scenario, we implement the model in a modified version of the Boltzmann solver CLASS to compute the relevant cosmological observables and perform a Bayesian parameter estimation analysis using data from the cosmic microwave background (CMB), baryon acoustic oscillations (BAOs), and Type Ia supernovae. The model naturally breaks the degeneracy between the dark energy equation of state and the total neutrino mass, yielding tight upper bounds of $\sum m_\nu< 0.067$ eV for flat spatial geometry and $\sum m_\nu< 0.116$ eV when curvature is included. We also provide forecasts for future probes, showing that the Simons Observatory, LiteBIRD, and Euclid configurations may reduce the uncertainty on $\sum m_\nu$ by $\approx 9\%$, while the precision on the quintessential parameter $\alpha_{QI}$ is improved by $\approx 72\%$. These results highlight the importance of consistently accounting for neutrino mass when assessing the viability of extensions to the standard cosmological model.
Read the full abstract

All authors Jamerson Rodrigues, Gabriel Rodrigues, Felipe B. M. dos Santos, Simony Santos da Costa, Jailson Alcaniz

Earth and Planetary Astrophysics

Time-variable Scattered Light in Herbig Disks Observed with Subaru/SCExAO

Camryn Mullin, Miles Lucas, Ruobing Dong et al. (+12 more)

Using the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument, we present near-infrared K-band polarimetric imaging of nine Herbig stars selected from a volume-limited sample within 200 pc. We detect the disks around MWC 480, HD 163296, and HD 143006 for the first time with SCExAO, and compare these observations with previous VLT/SPHERE datasets to identify surface-brightness variability. In MWC 480, we resolve two azimuthal brightness dips near the disk minor axis and find evidence that one of them shifted between 2021 and 2022. In HD 163296, we identify an apparent linear azimuthal motion of a localized peak in polarized intensity along the outer ring over a 15-month baseline. The rapid motion of these features relative to the local Keplerian velocity suggests that the observed variability is driven by changing illumination rather than physical material motion. Due to uncertainties in the underlying scattering background, however, we cannot determine the precise physical origin of the variability. No significant disk variability is detected in HD 143006 over a 10-month baseline. We also report the first detection of a protoplanetary disk using the fast-PDI mode on SCExAO, illustrating both the promise and current limitations of this observing mode. Finally, we report non-detections toward HD 144432, HD 56895, PDS 76, HIP 80425, HD 148352, and HIP 81474. All non-detections with Meeus classifications belong to Group II systems and are likely self-shadowed. For these six systems, we measure the system-integrated polarization fraction and angle of linear polarization, providing quantitative constraints on their unresolved circumstellar environments.
Read the full abstract

All authors Camryn Mullin, Miles Lucas, Ruobing Dong, Jun Hashimoto, Haochang Jiang, Doug Johnstone, Kellen Lawson, Sean Brittain, Olivier Guyon, Tomoyuki Kudo, Julien Lozi, Joan Nojita, He Sun, Motohide Tamura, Kevin Wagner

Astrophysics of Galaxies

An automated activity classification tool for optical galaxy spectra

C. Daoutis, A. Zezas, E. Kyritsis et al. (+2 more)

Reliable, versatile galaxy activity diagnostics are essential for understanding galaxy evolution. Traditional methods frequently necessitate extensive preprocessing, such as starlight subtraction and emission line deblending (e.g., H{\alpha} and [N II]), which can introduce substantial biases and uncertainties due to their model-dependent nature. In this work we developed an automated, diagnostic tool capable of distinguishing between star-forming (SF), active galactic nuclei (AGN), low-ionization nuclear emission-line regions (LINERs), composite, and passive galaxies. We developed a diagnostic tool based on a support vector machine trained on data from optical emission-line ratios and color selection criteria. From literature studies and exploring combinations of discriminatory feature schemes, we found that the equivalent widths of H{\beta}, [O III]{\lambda}5007, and H{\alpha}+[N II]{\lambda}6548,84 as key diagnostic features. Additionally, galaxies classified as AGN can be distinguished into broad- and narrow-line AGN by measuring the full quarter at the half-maximum of H{\alpha} and [N II] complex. We have developed a diagnostic tool that encompasses all activities of galaxies while achieving high performance scores across all of them. Our diagnostic achieves overall accuracy of 83% and recall of 79% for SF, 94% for AGN, 85% for LINER, 77% for composite, and 96% for passive galaxies. Our diagnostic tool significantly improves upon existing diagnostics as it eliminates the need for preprocessing (i.e., starlight subtraction or flux calibration) and spectral line fitting, includes all activity classes under one scheme, and distinguishes the two main AGN types. In addition, omitting starlight subtraction does not significantly reduce performance. Furthermore, Its narrow wavelength requirement enables use across a wide redshift range, making it ideal for high-z studies.
Read the full abstract

All authors C. Daoutis, A. Zezas, E. Kyritsis, K. Kouroumpatzakis, P. Bonfini

Astrophysics of Galaxies

ALMA Central Molecular Zone Exploration Survey (ACES) I: Overview

Steven N. Longmore, John Bally, Ashley T. Barnes et al. (+95 more)

The mass flows and energy cycles within the inner regions of galaxies exert a powerful influence on the evolution of the galaxy population. The centre of the Milky Way is the only galactic nucleus for which it is possible to resolve the physical mechanisms that drive these cycles, namely star formation and feedback, while also tracing global (>100 pc) processes which determine where and when star formation and feedback occur. We present an overview of ACES, the 'Atacama Large Millimeter/submillimeter Array (ALMA) CMZ Exploration Survey', a ~1.5" angular resolution, 0.2-3 km/s spectral resolution ALMA Band 3 (85-102 GHz), survey of the 'Central Molecular Zone' (CMZ) – the inner-100 pc of the Galaxy (l = 359.4 deg to 0.8 deg). ACES spectral setup is tuned to observe optimal tracers of the physical, chemical, and kinematic conditions in over 70 spectral features (e.g. HCO+, HNCO, SiO, H40alpha, complex molecules) of the gas in the CMZ, to derive the properties of all potentially star-forming Galactic Centre gas, from global scales (100 pc) to dense ~0.05 pc structures that are expected to host individual star-forming cores, down to sub-sonic (<0.4 km/s) velocity resolution. In this overview paper, we provide the scientific justification for the ACES survey, explain the choice of observational setup, and describe the data legacy products. Finally, we show some of the initial ACES data which highlight the power of ACES' combination of high angular resolution, unprecedented spatial dynamic range, sensitivity, spectral resolution and spectral bandwidth as an illustration of how ACES aims to understand how global processes set the location, intensity, and timescales for star formation and feedback in the CMZ.
Read the full abstract

All authors Steven N. Longmore, John Bally, Ashley T. Barnes, Cara Battersby, Laura Colzi, Adam Ginsburg, Jonathan D. Henshaw, Paul T. P. Ho, Izaskun Jiménez-Serra, J. M. Diederik Kruijssen, Elisabeth A.C. Mills, Maya A. Petkova, Mattia C. Sormani, Robin G. Tress, Daniel L. Walker, Jennifer Wallace, Emad Alkhuja, Lucia Armillotta, Nazar Budaiev, Rojita Buddhacharya, Alyssa Bulatek, Michael Burton, Natalie O. Butterfield, Laura A. Busch, Paola Caselli, Mélanie Chevance, Claire Cook, Samuel Crowe, Ana Karla Díaz-Rodríguez, Enrico DiTeodoro, Simon R. Dicker, Katarzyna M. Dutkowska, Adam Fairley, Christoph Federrath, Rubén Fedriani, Zi-Xuan Feng, Karl Fiteni, Gary Fuller, Pablo García, Javier Goicoechea, Philipp Girichidis, Simon C. O. Glover, Mark Gorski, Savannah R. Gramze, Qi-Lao Gu, H. Perry Hatchfield, Christian Henkel, Rebecca J. Houghton, Pei-Ying Hsieh, Yue Hu, Katharina Immer, Desmond Jeff, Janik Karoly, Jens Kauffmann, Ralf S. Klessen, Mark R. Krumholz, Alex Lazarian, Emily M. Levesque, Fu-Heng Liang, Dani Lipman, Xunchuan Liu, Xing Lu, Qiu-yi Luo, Alessandro Lupi, Laura McCafferty, S. Martín, Farideh Mazoochi, Mark R. Morris, Marie Nonhebel, Francisco Nogueras-Lara, Tomoharu Oka, Juergen Ott, Marco Padovani, Xing Pan, Jaime E. Pineda, Thushara G.S. Pillai, Marc W. Pound, Miguel Requena Torres, Denise Riquelme-Vásquez, Víctor M. Rivilla, Galaxy Salo, Álvaro Sánchez-Monge, Miriam G. Santa-Maria, Rainer Schoedel, Anika Schmiedeke, Matthias Schultheis, Howard A. Smith, Yoshiaki Sofue, Leonardo Testi, Grant R. Tremblay, Arianna Vasini, Gijs Vermariën, Alexey Vikhlinin, Serena Viti, Q. Daniel Wang, Fengwei Xu, Suinan Zhang, Qizhou Zhang

Astrophysics of Galaxies

Quasars behind the disk of M31 galaxy

P. Nedialkov, B.F. Williams, V.D. Ivanov et al. (+6 more)

We aim to increase the limited number of quasars behind M31, necessary for probing the chemical content of the gas and for proper motion reference, with reliable and homogeneous redshift measurements from emission lines. We carried out spectroscopic follow up of 32 quasar candidates. We confirm 23 quasars: two are new discoveries (J004029.727+403705.68 and J004215.489+412031.52) and the rest were reported elsewhere, but with somewhat deficient analysis; 16 spectra are published for the first time. We report new homogeneous redshifts for 34 quasars (from 40 spectra, adding 17 from archives) and summarize all available information about bona-fide quasars with reliable redshift, bringing their number to 124 within the mu_B=26 mag/arcsec^2 isophote. We carried out a comparison of redshifts from different sources and excluded some objects with redshifts derived from low-resolution spectra. We derive the reddening for them from the color excess with respect to dereddened counterparts with similar redshifts in the field. Comparisons of our reddenings with M31 reddening maps found no significant correlations. Most QSOs behind M31 show low reddening and do not probe high-extinctions underlining the need to identify fainter quasars behind nearby galaxies, especially behind higher extinction regions – probably due to a bias towards following up brighter and less extinct candidates. Finally, the redshifts derived from low-resolution spectra must be treated with caution, because they can contain significant errors.
Read the full abstract

All authors P. Nedialkov, B.F. Williams, V.D. Ivanov, A. Valcheva, Y. Solovyeva, A. Vinokurov, E. Malygin, D. Oparin, O. Sholukhova

Solar and Stellar Astrophysics

Inspectorch: Efficient rare event exploration in solar observations

C. J. Díaz Baso, I. J. Soler Poquet, C. Kuckein et al. (+2 more)

The Sun is observed in unprecedented detail, enabling studies of its activity on very small spatiotemporal scales. However, the large volume of data collected by our telescopes cannot be fully analyzed with conventional methods. Popular machine learning methods identify general trends from observations, but tend to overlook unusual events due to their low frequency of occurrence. We study the applicability of unsupervised probabilistic methods to efficiently identify rare events in multidimensional solar observations and optimize our computational resources to the study of these extreme phenomena. We introduce Inspectorch, an open-source framework that utilizes flow-based models: flexible density estimators capable of learning the multidimensional distribution of solar observations. Once optimized, it assigns a probability to each sample, allowing us to identify unusual events. We apply this approach by applying it to observations from the Hinode Spectro-Polarimeter, the Interface Region Imaging Spectrograph, the Microlensed Hyperspectral Imager at Swedish 1-m Solar Telescope, the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Extreme Ultraviolet Imager on board Solar Orbiter. We find that the algorithm assigns consistently lower probabilities to spectra that exhibit unusual features. For example, it identifies profiles with very strong Doppler shifts, uncommon broadening, and temporal dynamics associated with small-scale reconnection events, among others. As a result, Inspectorch demonstrates that density estimation using flow-based models offers a powerful approach to identifying rare events in large solar datasets. The resulting probabilistic anomaly scores allow computational resources to be focused on the most informative and physically relevant events. We make our Python package publicly available at https://github.com/cdiazbas/inspectorch.
Read the full abstract

All authors C. J. Díaz Baso, I. J. Soler Poquet, C. Kuckein, M. van Noort, N. Poirier

Astrophysics of Galaxies

BASS LV. Connecting X-ray variability with AGN physical properties and a new path to Cosmological distances

Matilde Signorini, Federica Ricci, Alessia Tortosa et al. (+18 more)

X-ray variability is a well-established characteristic of active galactic nuclei (AGN), known to correlate inversely with both the supermassive black hole mass and luminosity, although the degree of each remains a topic of debate. The potential of X-ray variability as a proxy for MBH or for intrinsic LX has led to proposals to use AGN as standard candles to test cosmological models. However, the large intrinsic dispersion in these relations has limited their practical applications. In this work, we investigate the dependence of X-ray variability on AGN physical properties using a sample of 134 Seyfert 1 galaxies from the BAT AGN Spectroscopic Survey (BASS), which is the largest sample to date, more than three times larger than those used in previous studies. Contrary to earlier findings, we observe that X-ray variability correlates with luminosity just as strongly as with MBH. Furthermore, we still do not find evidence for the expected anti-correlation between variability and Eddington ratio, even when using refined bolometric luminosities from SED fitting to compute the Eddington ratio. From a cosmological perspective, the increased sample size reduces the scatter in the log(L)-log(exvar) relation to ~0.63 dex - a significant improvement over previous results, but still too large to serve as competitive standard candles, when compared to SNIa (uncertainties on distances of ~5-10%) or the L(X)-L(UV) relation in quasars (uncertainties of 10-12%). We tested including the width of broad emission lines as additional parameters, but found that this does not significantly lower the observed dispersion, contrary to previous studies on smaller samples. Finally, we discuss how future X-ray missions such as AXIS and NewAthena will improve this scenario by enabling precise variability measurements for thousands of AGN up to redshift z~3, thereby enabling it as a new cosmological probe.
Read the full abstract

All authors Matilde Signorini, Federica Ricci, Alessia Tortosa, Stefano Bianchi, Fabio La Franca, Franz E. Bauer, Fiona A. Harrison, Kohei Ichikawa, Arghajit Jana, Michael J. Koss, Tingting Liu, Kyuseok Oh, Alessandro Peca, Meredith Powell, Claudio Ricci, David B. Sanders, Roberto Serafinelli, Daniel Stern, Benny Trakhtenbrot, Ezequiel Treister, Megan Urry

Solar and Stellar Astrophysics

Evidence for Sympathetic Flaring in TESS Data

Veronica Pratt, Jason R. Reeves, David V. Martin et al. (+3 more)

Most flares on the Sun occur at random, but there is a small percentage of "sympathetic flaring" – the triggering of one flare by another. Previously there had been no widespread confirmation of sympathetic flares on other stars. In this work, we developed a new flare detection algorithm that is sensitive to closely-separated and overlapping stellar flares. We applied it to TESS data and discovered ~ 220,000 flares on ~ 16,000 stars, the majority of which are M-dwarfs. The wait time distribution between flares demonstrates an excess of closely-separated flares, relative to expectations from a Poisson process. We attribute this to sympathetic flares, occurring at a rate of between 4% and 9%, which matches the rate seen on the Sun. Our result is the first statistically robust detection of sympathetic flares on other stars, demonstrating a commonality between the Sun and low-mass stars.
Read the full abstract

All authors Veronica Pratt, Jason R. Reeves, David V. Martin, Andy B. Zhang, Andrew Korkus, S. Edelman

Instrumentation and Methods for Astrophysics

Compute System Organization for High Frequency High Order Wavefront Sensing and Control

Barry Lyu, Vaibhavi Manjarekar and Nathaniel Bleier

Maintaining long-term wavefront stability is critical for the Habitable Worlds Observatory (HWO), which targets contrasts approaching $10^{-10}$ and therefore requires continuous dark-zone maintenance using high-order wavefront sensing and control (HOWFSC). Prior work has advanced HOWFSC algorithms and profiled candidate implementations on radiation-hardened processors, highlighting a substantial gap between the computational demands of LUVOIR-scale HOWFSC and the capabilities of current onboard spacecraft hardware. In this paper, we argue that this gap can be closed by offloading the HOWFSC pipeline to a dedicated co-flying compute satellite at Sun-Earth L2. This approach enables the use of modern, radiation-tolerant high-performance processors without increasing risk to the primary observatory. We show that such an architecture can increase the end-to-end control cadence from the sub-hertz regime typical of radiation-hardened onboard processing or ground-in-the-loop operation to tens and even hundreds of hertz. We evaluate commercial hardware platforms in terms of performance and feasibility, and we propose custom architectures that enable higher control frequencies with significant power consumption reductions. Finally, we outline system-level considerations for co-flying compute, including reliability, satellite integration, and inter-satellite communication constraints.
Read the full abstract

Earth and Planetary Astrophysics

Planet formation at the inner edge of the dead zone I. the interplay between accretion outbursts and dust growth

Alexandros Ziampras, Tilman Birnstiel, Nicolas Kaufmann et al. (+2 more)

The inner edge of the dead zone in protoplanetary disks has been shown to periodically go unstable, leading to accretion outbursts and annular substructure within the dead zone. While dust opacities play a key role in this process, the thermal and dynamical effects of dust drift and growth have not been fully explored. We investigate the evolution of accretion outbursts in the inner disk and their impact on the formation of dust-rich substructure with a fully dynamic dust model. In doing so, we aim to highlight the importance and limitations of dust growth in forming planets in this region. We carry out radiation hydrodynamics simulations of a protoplanetary disk including prescriptions for the structure of the inner edge of the dead zone, viscous and irradiation heating, radiative cooling, dust-gas dynamics, and dust evolution. We find that accretion outbursts at the inner disk edge can lead to the formation of multiple dust rings that extend deep inside the dead zone (~1 au) and diffuse on viscous timescales (~10 kyr for alpha=1e-4). The rings contain dust masses of up to ~1.6 Earth masses, possibly kickstarting planet formation. Dynamic modeling of dust fragmentation enhances the total opacity during the burst, yielding more intense outbursts that penetrate deeper into the dead zone. Our results highlight the thermal and dynamical importance of treating dust dynamics self-consistently in models of accretion outbursts. Additional modeling is needed to characterize the inevitable nonaxisymmetric structures arising from accretion outbursts and their observational prospects.
Read the full abstract

All authors Alexandros Ziampras, Tilman Birnstiel, Nicolas Kaufmann, Michael Cecil, Thomas Pfeil

Instrumentation and Methods for Astrophysics

Neural Bayesian updates to populations with growing gravitational-wave catalogs

Noah E. Wolfe, Matthew Mould, John Veitch et al. (+1 more)

As gravitational-wave catalogs grow, they will become increasingly computationally expensive to analyze in their entirety, especially when inferring astrophysical source populations with high-dimensional, flexible models. Bayesian statistics offers a natural remedy, letting us update our knowledge of physical models as new data arrive, without re-analyzing existing data. However, doing so requires the posterior probability density of model parameters for previous observations, which is typically intractable. Here, we use variational neural posterior estimation to rapidly update the inferred population of binary black holes as data are observed in gravitational-wave detectors. We apply this approach to real and simulated catalogs analyzed with both low- and high-dimensional population models, testing the reliability of three update cadences: with new catalogs of sources, month by month during an observing run, and as each new signal arrives. We investigate the success and failure modes of neural sequential updates, finding that the robustness of updating is sensitive to the information contained in each update and that updating is most effective when performed with larger segments of data. We outline one additional scientific application enabled by Bayesian updating: identification of events that are individually informative about the population. Neural Bayesian updates to astrophysical population models also provide efficient likelihood representations for joint analyses with other data, e.g., standard-siren cosmology, and similar methods can be used to perform Bayesian stochastic background searches.
Read the full abstract

All authors Noah E. Wolfe, Matthew Mould, John Veitch, Salvatore Vitale

Astrophysics of Galaxies

ALMA Central molecular zone Exploration Survey (ACES) III: Molecular line data reduction and HNCO and HCO$^{+}$ data

Daniel L. Walker, Adam Ginsburg, Ashley T. Barnes et al. (+64 more)

The ALMA Central molecular zone Exploration Survey (ACES) large program has observed the inner ~ 200 pc of the Milky Way at 3 mm (Band 3) using ALMA's 12m, 7m, and Total Power arrays. With an angular resolution of ~ 2", ACES provides a contiguous, multi-scale view of the Central Molecular Zone (CMZ) via the dust continuum and a suite of molecular lines. We present an overview of the molecular line data processing for ACES and describe the first data release. We showcase the HNCO (4-3) and HCO$^{+}$ (1-0) data, which were targeted at high spectral resolution (0.2 km s$^{-1}$) to trace the kinematics of the molecular gas in the CMZ. The HNCO and HCO$^{+}$ maps are compared with previous single-dish CMZ surveys and discrete ALMA observations of CMZ clouds to demonstrate the quality of the data. We highlight the ubiquity of parsec-scale, linear absorption features traced by HCO$^{+}$. Their origin is unknown, and ACES provides the first opportunity to study these enigmatic features throughout the CMZ. We release the HNCO and HCO$^{+}$ cubes for all 45 ACES fields, along with the full cube mosaics which combine all fields into a contiguous mosaic of the CMZ. We additionally provide advanced products of these full mosaics, including integrated and peak intensity, noise, and position-velocity maps. These products provide substantial legacy value for the community, offering an unparalleled view of the physical and kinematic structure of the dense gas in the CMZ.
Read the full abstract

All authors Daniel L. Walker, Adam Ginsburg, Ashley T. Barnes, Xing Lu, Pei-Ying Hsieh, Álvaro Sánchez-Monge, Savannah R. Gramze, Nazar Budaiev, Marc W. Pound, Jaime E. Pineda, Alyssa Bulatek, Claire Cook, Jonathan D. Henshaw, Katharina Immer, Namitha Issac, Desmond Jeff, Fu-Heng Liang, Steven N. Longmore, Elisabeth A.C. Mills, Sergio Martín, Xing Pan, Thushara G.S. Pillai, Qizhou Zhang, John Bally, Cara Battersby, Laura Colzi, Paul T. P. Ho, Izaskun Jiménez-Serra, J. M. Diederik Kruijssen, Maya A. Petkova, Mattia C. Sormani, Robin G. Tress, Jennifer Wallace, J. Armijos-Abendaño, Lucia Armillotta, N. Bijas, Rojita Buddhacharya, Laura A. Busch, Natalie O. Butterfield, Mélanie Chevance, Samuel Crowe, Ana Karla Díaz-Rodríguez, Katarzyna M. Dutkowska, Christoph Federrath, Rubén Fedriani, Pablo García, Simon C. O. Glover, Qi-Lao Gu, H Perry Hatchfield, Rebecca J. Houghton, Yue Hu, Janik Karoly, Ralf S. Klessen, Mark R. Krumholz, Farideh Mazoochi, Francisco Nogueras-Lara, Dylan Paré, Denise Riquelme-Vásquez, Víctor M. Rivilla, Miriam G. Santa-Maria, Anika Schmiedeke, Yoshiaki Sofue, Volker Tolls, Q. Daniel Wang, Gwenllian M. Williams, Fengwei Xu, Suinan Zhang

Astrophysics of Galaxies

Willman 1 Revisited: The Kinematics, Chemistry, and Orbital Properties of a Potentially-Disrupting Dwarf Galaxy

Camille Chiu, Marla Geha, William Cerny et al. (+4 more)

The ultra-faint Milky Way satellite Willman 1 (W1; $M_V = -2.6$; $r_{\rm half} \sim27$ pc) was the first stellar over-density found via resolved stars in the Sloan Digital Sky Survey, yet its classification as either a dwarf galaxy or star cluster remains ambiguous. Using new Keck/DEIMOS spectroscopy, HST/ACS photometry, and orbital modeling, we re-examine the nature of W1. From our updated sample of 56 member stars, we find that past analyses included four binaries and seven nonmembers, identified here using Gaia proper motions and updated velocities. We continue to find a velocity dispersion consistent with previous analyses, measuring $\sigma_v = 4.7^{+1.5}_{-1.3}$ km s$^{-1}$ from 49 stars out to $3~r_{\rm half}$. If W1 is in equilibrium, this suggests a dynamical mass of $5.9^{+3.7}_{-3.4} \times 10^5~M_{\odot}$ and a mass-to-light ratio of $(M/L)_V = 660 \pm 590$. Based on Ca II triplet measurements, we estimate an iron abundance of [Fe/H] $= -2.45^{+0.12}_{-0.13}$ and a metallicity dispersion of $\sigma_{\rm [Fe/H]} = 0.30^{+0.15}_{-0.11}$ dex. We confirm that W1 does not exhibit mass segregation inside $\sim1~r_{\rm half}$. Our best-fit orbital model predicts that W1 is at apocenter, implying that W1 has been closer to the Milky Way in the recent past, reaching a pericentric distance $\lesssim 25$ kpc from the Galactic center $\sim0.3$ Gyr ago. Given its internal kinematics, metallicity spread, and lack of mass segregation, we conclude that W1 is a galaxy. However, given its orbit and structural properties, which suggest that W1 might be tidally disrupted, and the difficulty of identifying a pure member sample, we caution that the measured internal velocity dispersion may not accurately reflect the dynamical mass of this system.
Read the full abstract

All authors Camille Chiu, Marla Geha, William Cerny, Nitya Kallivayalil, Hannah Richstein, Christopher T. Garling, Beth Willman

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Pseudo-Newtonian potential for accretion disks in a modified gravity spacetime around the black hole and underlying properties

Sriraj Chandra and Banibrata Mukhopadhyay

We construct a pseudo-Newtonian potential (PNP) corresponding to a rotating black hole solution in a modified gravity (MGR) framework using a metric-based prescription. The motivation is to enable realistic accretion disk studies in MGR, where full relativistic MHD simulations remain computationally prohibitive. Effective potentials and the underlying Newtonian-like forces are derived for both massive and massless particles in the equatorial plane, relevant for disk dynamics. The reliability of the PNP is tested by comparing key orbital properties – marginally stable, marginally bound, photon orbits and energies at marginally stable orbit radii – with exact MGR predictions. The PNP reproduces the marginally stable and photon orbits exactly, while marginally bound orbits and specific energies deviate by less than about 7-10%. The influence of the MGR parameter on particle dynamics and effective potentials is analyzed, revealing non-trivial departures from simple Newtonian intuition. The study demonstrates that the proposed PNP accurately captures essential spatial properties of MGR spacetime and provides an efficient, physically consistent tool for investigating accretion phenomena and strong-gravity astrophysics beyond general relativity.
Read the full abstract

Astrophysics of Galaxies

ALMA Central molecular zone Exploration Survey (ACES) VI: ALMA Large Program Reveals a Highly Filamentary Central Molecular Zone

Cara Battersby, Miriam G. Santa-Maria, Dani Lipman et al. (+44 more)

The Central Molecular Zone (CMZ) of the Milky Way is the way station that primarily controls how much gas flows from the disk of the Galaxy towards the central nucleus. While this region is well documented to have extreme gas properties that clearly distinguish it from the rest of the Galaxy, the properties of the bulk molecular gas at high angular resolution are relatively unexplored. Band 3 data from the ALMA (Atacama Large Millimeter/Submillimeter Array) large program ACES (ALMA CMZ Exploration Survey) reveal the highly filamentary nature of CMZ molecular gas at high resolution (3" or 0.1pc) across the entire CMZ. Visual inspection of these data suggests that there are at least two general classes of elongated structures, which we identify as: i) large-scale (10 pc) filamentary structures (LFs) and ii) a ubiquitous population of small-scale (about 1 pc) filamentary structures (SFs). We present detailed morphological and kinematic properties towards three structures in each category, as well as their association with magnetic fields and the correlation of HNCO 4(0,4)-3(0,3) with other molecular species. Our investigation reveals that these structures are largely coherent in position-position-velocity space. The alignment with the magnetic field structure is mixed, with some parallel, some perpendicular, and some intermediate alignments. We find that LFs likely trace pieces of contiguous CMZ orbital structures and are a manifestation of global CMZ dynamics. The second class, SFs, are pervasive and may be the result of complicated turbulence and shearing dynamics in the CMZ gas flows, as seen in numerical simulations.
Read the full abstract

All authors Cara Battersby, Miriam G. Santa-Maria, Dani Lipman, Dylan M. Paré, Rachel R. Lee, Pablo García, Izaskun Jiménez-Serra, Xing Pan, Daniel L. Walker, Jack Sullivan, Danya Alboslani, H Perry Hatchfield, Yue Hu, Alex Lazarian, Jennifer Wallace, Qizhou Zhang, Xing Lu, Elisabeth A.C. Mills, Adam Ginsburg, Ashley T. Barnes, Pei-Ying Hsieh, Jonathan D. Henshaw, Steven N. Longmore, John Bally, Laura Colzi, Paul T. P. Ho, Maya A. Petkova, Mattia C. Sormani, N. Bijas, Alyssa Bulatek, Natalie O. Butterfield, Christoph Federrath, Simon C. O. Glover, Mark D. Gorski, Savannah R. Gramze, Christian Henkel, Janik Karoly, Ralf S. Klessen, Sergio Martín, Francisco Nogueras-Lara, Jaime E. Pineda, Denise Riquelme-Vásquez, Víctor M. Rivilla, Álvaro Sánchez-Monge, Anika Schmiedeke, Yoshiaki Sofue, Volker Tolls

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Tests of general relativity in pseudo-Newtonian approach

Naman Goyal, Banibrata Mukhopadhyay and Ashish Kumar Meena

We investigate the extent to which pseudo-Newtonian gravitational potentials can reproduce classic tests of general relativity without resorting to full general relativistic formalisms. This is useful for the researchers seeking intuitive insight into relativistic gravity. Focusing on the perihelion precession of Mercury, gravitational redshift, and gravitational light bending, we derive analytical expressions for orbital precession and demonstrate that, with suitable physically acceptable parameters, pseudo-Newtonian approaches can accurately reproduce the observed perihelion advance and gravitational redshift. However, we confirm that no single potential consistently captures all relativistic effects. In particular, while certain parameters yield agreement with general relativity for planetary motion and redshift, they fail to reproduce gravitational lensing over a broad range of impact parameters. Our results highlight both the usefulness and limitations of pseudo-Newtonian methods in modeling gravitational phenomena. Although the pseudo-Newtonian approach cannot serve as universal substitutes for general relativity, especially in strong-field regimes, it provides valuable semi-analytical insight and pedagogical simplicity. Our results indicate the usefulness of the pseudo-Newtonian approach to uncover more complicated phenomena involved with strong field gravity in possibly modification to general relativity.
Read the full abstract

Astrophysics of Galaxies

The First Systematic Survey of Stellar Halos in High-Inclination Galaxies Reveals Unusually Quiescent Merger Histories of Nearby Galaxies

Bojun Tao, Hong-Xin Zhang, Wenting Wang et al. (+8 more)

Stellar halos are the only major stellar component of disk galaxies that lack systematic observational characterization, yet they encode critical information about galaxy merger histories. We present the first systematic census of stellar halos in a large, flux-limited sample of 169 high-inclination central galaxies with stellar masses 7.3 <= log Mstar/Msun <= 11.0 and redshift z < 0.1, using HSC-SSP Deep optical images. Stellar halos are detected in 93 galaxies, primarily through their low isophotal ellipticities in the outskirts, improving upon conventional methods of stellar halo identification. The halo detection rate reaches ~ 50% at log Mstar/Msun > 9.9 and >= 70% for Milky Way (MW)-mass galaxies. We derive halo surface brightness profiles, colors, and masses, finding that stellar halos generally follow power-law radial profiles. Higher-mass galaxies, on average, exhibit smaller power-law indices and larger halo mass fractions, indicating more extended halos and more active merger histories. A significant stellar halo color-mass correlation, driven mainly by the mass-metallicity relation, suggests dominance by a few massive accretion events. MW-mass galaxies have a median stellar halo fraction of 10% +/- 5%. Among nearby galaxies with halo measurements within 25 Mpc, two thirds (including the MW) lie below the mean stellar halo fraction-galaxy mass relation. Overall, the nearby galaxies show a median halo deficit of ~ 0.3 dex, implying unusually quiescent merger histories. We show that this deficit follows a broader trend in which typical halo fractions increase with heliocentric distance, tracking the gradual rise in matter density toward the cosmic average by z <= 0.07.
Read the full abstract

All authors Bojun Tao, Hong-Xin Zhang, Wenting Wang, Enci Wang, Guangwen Chen, Huiyuan Wang, Lijun Chen, Qian-Hui Chen, Song Huang, Xu Kong, Yu Rong

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

INFLAVON: CMB as cosmic tracer of Flavor physics

Mu-Chun Chen, Anish Ghoshal, V. Knapp-Perez et al. (+3 more)

We unify one of the most widely studied frameworks to explain the hierarchical structure of the flavor sector in the Standard Model, the Froggatt-Nielsen mechanism, with cosmic inflation. We propose that the complex scalar field, the so-called flavon, which breaks the Froggatt-Nielsen $U(1)$ symmetry and generates the Yukawa couplings of the Standard Model, to also drive inflation, which we dub as Inflavon. After inflation ends, the decay of the inflavon reheats the Universe, establishing a novel link between early Universe cosmology and flavor physics. As concrete examples, we present realizations where the inflavon potential is described by an $\alpha$-attractor potential. We then compute the resulting CMB observables, specifically the spectral index ($n_s$), the tensor-to-scalar ratio ($r$), and the amplitude of scalar perturbations ($A_s$) as functions of the underlying Froggatt-Nielsen model parameters. We identify the parameter space in Froggatt-Nielsen models involving the scale of Flavor symmetry breaking $\Lambda_{\rm FN}$ and FN charges which is ruled out by Planck and ACT data, as well as the region that could be probed by next-generation CMB experiments like CMB-S4, SO and LiteBIRD. We also discuss inflavon as dark matter and its isocurvature constraints.
Read the full abstract

All authors Mu-Chun Chen, Anish Ghoshal, V. Knapp-Perez, Xueqi Li, Xiang-Gan Liu, Cameron Moffett-Smith