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Physics Astrophysics

astro-ph Watch Astrophysics

Saturday 22 November

Cosmology and Nongalactic Astrophysics

Cosmic Shear constraints from HSC Year 3 with clustering calibration of the tomographic redshift distributions from DESI

J. Choppin de Janvry, B. Dai, S. Gontcho A Gontcho et al. (+2 more)

We reanalyze cosmological constraints from Hyper Suprime-Cam (HSC) Y3 shear-shear correlation function using new calibration of the tomographic redshift distribution via the clustering redshifts method with DESI spectroscopy presented in Choppin de Janvry et al. (2025a). We present both importance sampling of the original MCMC chains by HSC, applying the weights of our newly calibrated $\Delta z$ priors, as well as full MCMC analysis with new photometric redshift distributions, finding consistent results between the two. We obtain the growth of structure parameter $S_8\equiv\sigma_8\sqrt{\Omega_m/0.3}=0.804^{0.019}_{-0.018}$, compared to previous HSC Y3 result of $S_8=0.769^{+0.031}_{-0.034}$, which is a 1.8 reduction of error due to the improved clustering redshift calibrations, with the central value shifting considerably higher towards Planck cosmology. With the new photometric redshift calibration, HSC Y3 has comparable constraining power to the recent KIDS Legacy and DES Y6 results.
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All authors J. Choppin de Janvry, B. Dai, S. Gontcho A Gontcho, U. Seljak, T. Zhang

Cosmology and Nongalactic Astrophysics

Full calibration of the tomographic redshift distribution from the HSC PDR3 Shape Catalog with DESI

J. Choppin de Janvry, S. Gontcho A Gontcho, U. Seljak et al. (+53 more)

The calibration of tomographic redshift distributions is essential for cosmological analysis of weak lensing data. In this work, we calibrate all four tomographic bins of the Hyper Suprime Camera (HSC) weak lensing catalog with the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 and 2 using the clustering redshifts technique. We include z > 1.2 redshift sources such as emission line galaxies (ELG) and quasars (QSO) sources in our calibration, which were not available in the previous HSC calibration (Rau et al. 2022), allowing a complete calibration of all the redshift bins. We find the first tomographic bin exhibits a small shift towards low redshifts. The second bin is in good agreement with the photometric calibration, while third and fourth bin exhibit a shift towards higher redshifts. However, these shifts are considerably smaller than the shifts obtained in the HSC Year 3 cosmic shear analyses. We evaluate the impact of galaxy bias and magnification effects from all the samples on the measurements, finding them to be small, and we propose corrections to reduce them further. Specifically, we relax the assumption of linear bias and only assume no redshift evolution of the cross-correlation coefficient, allowing us to leverage smaller clustering scales. We model the redshift distributions with splines and compare our results to previous analyses as well as to other parameterizations found in literature. For the two high-redshift tomographic bins, we find the shifts to higher redshifts with respect to the measurements performed in Rau+2022 to be $\Delta z_3=-0.043^{+0.022}_{-0.020}$ and $\Delta z_4=-0.050^{+0.012}_{-0.012}$.
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All authors J. Choppin de Janvry, S. Gontcho A Gontcho, U. Seljak, A. Baleato Lizancos, E. Chaussidon, W. d'Assignies, J. DeRose, S. Heydenreich, E. Paillas, D. Valcin, T. Zhang, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, F.J. Castander, T. Claybaugh, A. Cuceu, A. de la Macorra, P. Doel, S. Ferraro, A. Font-Ribera, J.E. Forero-Romero, E. Gaztañaga, G. Gutierrez, H.K. Herrera-Alcantar, K. Honscheid, M. Ishak, R. Joyce, S. Juneau, R. Kehoe, D. Kirkby, T. Kisner, A. Kremin, O. Lahav, C. Lamman, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, S. Nadathur, N. Palanque-Delabrouille, W.J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, J. Silber, D. Sprayberry, G. Tarlé, B.A. Weaver, R. Zhou

High Energy Astrophysical Phenomena

Verifying the failing supernova constraint on dark photons with two-dimensional hydrodynamic simulations

Kanji Mori, Tomoya Takiwaki and Kazunori Kohri

Recent studies on the dark photon (DP) production in collapsing stars argue that the cooling effect induced by DPs can hinder supernova explosions and lead to a “failing supernova" constraint on the photon-DP mixing parameter $\epsilon$. In order to verify the idea, we perform two-dimensional neutrino-radiation hydrodynamic simulations coupled with the DP production with the masses of 0.3 and 0.45\,MeV. We find that the shock revival does not happen until the end of the simulations when $\epsilon\gtrsim3\times10^{-9}$. The photon-DP mixing parameter above this value can be excluded by the failing supernova argument. Interestingly, our constraint roughly coincides with the one reported by the previous studies which adopted the post-processing framework. This result motivates one to investigate a wider parameter range of DPs with self-consistent simulations and evaluate uncertainties in the constraint.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Hawking-radiation-ignited autocatalytic formation of primordial black holes

Alexander Yakimenko

We propose and analyze an autocatalytic mechanism in which bursts of Hawking radiation from evaporating micro-primordial black holes (PBHs) trigger the collapse of near-critical plasma overdensities. In a primordial plasma seeded with such patches, this feedback self organizes into a traveling ignition front that successively forms new PBHs and then self-quenches as the Universe expands. A minimal reaction-diffusion model yields conservative criteria for ignition and freeze-out and predicts a stochastic gravitational-wave background with a sharp causal low-frequency edge set by the freeze-out correlation length and largely insensitive to Planck-scale PBH endpoint microphysics. The resulting sub-Hz-to-audio band and amplitudes satisfy cosmological energy-injection bounds, providing a clean, testable target for forthcoming gravitational-wave observatories.
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Solar and Stellar Astrophysics

B[e]-star CI Cam: a high-resolution spectrum atlas in the range of 395$\div$780 nm

Valentina G. Klochkova, Anatoly S. Miroshnichenko, Victoria N. Komarova et al. (+1 more)

The atlas of the spectrum of the B[e] star CI Cam obtained with the 6-meter BTA telescope in combination with the NES spectrograph in the wavelength interval of 395$\div$780 nm with a resolution of $\lambda/\Delta\lambda\ge60\,000$ is presented. The atlas contains about 400 spectral features and illustrates the diversity of spectral features of the unique star, forming in a complex circumstellar environment. The spectrum is dominated by forceful single-peaked HI, HeI emissions and numerous double-peaked permitted and forbidden emissions of ions of chemical elements starting from the CNO triad up to metals (Mg, Al, Ti, V, Cr, Fe) with practically “rectangular” profiles. The FeII and [FeII] emissions predominate in the spectrum. However, several other double-peaked forbidden ion emissions were also detected: [VII], [Cr II], [Ni II]. The atlas is presented graphically, with a separate figure corresponding to each echelle order. A list of identified lines, including a number of known interstellar features is presented in table form. CI Cam supergiant status has been confirmed.
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All authors Valentina G. Klochkova, Anatoly S. Miroshnichenko, Victoria N. Komarova, Nonna S. Tavolzhanskaya

Astrophysics of Galaxies

ACES: The Magnetic Field in Large Filaments in the Galactic Center

Dylan M. Paré, Zi-Xuan Feng, Yue Hu et al. (+33 more)

The Galactic Center (GC) is an extreme region of the Milky Way that is host to a complex set of thermal and non-thermal structures. In particular, the GC contains high-density gas and dust that is collectively referred to as the Central Molecular Zone (CMZ). In this work, we study a subset of HNCO filaments identified in band 3 ALMA observations of the GC obtained by the ALMA CMZ Exploration Survey (ACES) that are comparable to high density filaments identified in the Galactic Disk. We compare the orientation of the magnetic field derived from 214 um SOFIA and 850 um JCMT observations with the filament orientation to determine which mechanisms dominate the formation of these filaments. We observe a large range of magnetic orientations in our observed filaments indicating the complex environments the filaments are located in. We also compare the observational results to synthetic data sets created using an MHD model of the GC. Our analysis reveals that the dominant mechanisms local to the HNCO filaments vary throughout the GC with some filaments being dominated by supersonic turbulence and others by subsonic turbulence. The comparison to synthetic observations indicates that the observed filaments are in magnetically dominated environments that could be supporting these filaments against collapse. Our results on the CMZ filaments are also compared to results obtained on similar filaments located in the Galactic Disk, and we find that the filaments studied here are possible CMZ analogs to the dense filamentary "bones" observed previously in the Galactic Disk.
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All authors Dylan M. Paré, Zi-Xuan Feng, Yue Hu, Maya A. Petkova, Jack Sullivan, Robin G. Tress, Cara Battersby, Janik Karoly, Alex Lazarian, Dani Lipman, Xing Pan, Marco Donati, Mattia C. Sormani, John Bally, Ashley T. Barnes, Natalie O. Butterfield, Laura Colzi, Christoph Federrath, Pablo Garcia, Adam Ginsburg, Savannah R. Gramze, Anika Schmiedeke, Christian Henkel, Jonathan D. Henshaw, Paul T. Ho, Pei-Ying Hsieh, Izaskun Jimenez-Serra, Ralf S. Klessen, J. M. Diederik Kruijssen, Steven N. Longmore, Xing Lu, Elisabeth A.C. Mills, Álvaro Sánchez-Monge, Daniel L. Walker, Jennifer Wallace, Qizhou Zhang

Astrophysics of Galaxies · Cross-listed from gr-qc

Constraining linear form of $f(\mathcal{R,G,T})$ gravity from astrophysical observations of the Pulsar U1724

G.G.L. Nashed

In this work we examine the internal structure of compact stars within an extended gravitational framework described by the function $f(\mathcal{R},\mathcal{G},\mathcal{T})$. Throughout this work, the quantity $\mathcal{R}$ refers to the curvature scalar formed from the Ricci tensor. The term $\mathcal{G}$ denotes the Gauss–Bonnet curvature invariant, while $\mathcal{T}$ corresponds to the trace obtained by contracting the matter energy-momentum tensor. Our analysis is directed toward massive radio pulsars with masses above $1.8\,M_{\odot}$, which provide an exceptional testing ground for gravity under conditions inaccessible to laboratory experiments. Adopting the linear form $f(\mathcal{R},\mathcal{G},\mathcal{T})=\mathcal{R}+\alpha\,\mathcal{G}+\beta\,\mathcal{T}$ where $\alpha$ and $\beta$ are parameters of suitable dimensionality,\footnote{$\alpha$ has dimensions of $[L^{2}]$ and $\beta$ carries units of $[N^{-1}]$.} we obtain an exact analytic solution for static anisotropic stellar matter in hydrostatic equilibrium. This solution allows all physical quantities to be expressed in terms of the dimensionless parameters $ \alpha_{1}=\alpha/R^{2},\qquad \beta_{1}=\beta/\kappa^{2}$ together with the compactness $C=2GM/(Rc^{2})$. We constraint the two parameters $\alpha$ and $\beta$ by matching the model with the mass and radius of pulsar U1724 requires restricting these parameters to $\alpha_{1}=\pm0.023$ and $\beta_{1}=\pm0.001$, where $\kappa^{2}=8\pi G/c^{4}$ is the standard Einstein coupling. The resulting stellar configuration satisfies the causal bound on the radial sound speed, $c_{s}^{2}<c^{2}/3$, distinguishing it from the corresponding behaviour in general relativity.
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Solar and Stellar Astrophysics

Outbursts in ultra-compact AM CVn binaries

Gavin Ramsay

AM CVn binaries are the most compact of accreting binaries having orbital periods in the range ~5-70 min. They consist of a white dwarf accreting hydrogen deficient material from a degenerate or semi-degenerate star and are predicted to be amongst the verification sources for future gravitational wave observatories such as LISA. Using the recent catalogue of Green et al (2025) I focus attention on the orbital period range in which outbursts are seen from AM CVn's. I examine in more detail the outburst properties of KL Dra which has an outburst every few months and has many sectors of TESS data as an open resource. Using observational data on the outbursting systems in general, I compare the outburst recurrence time, duration and amplitude as a function of orbital period with the predictions of the disc instability model. The recurrence time is well described, although there is some evidence that the amount of material in the disc at the end of the quiescence phase is less than earlier model assumptions. The distribution of the outburst duration appears to be dependent on the cadence of the observations and how it is defined. Similarly the amplitude distribution is dependent on cadence and the filter, which causes an apparent spread in distribution. Both of these features need to be systematically studied using consistent benchmarks. AM CVn binaries remain an excellent sources to test models which aim to predict the properties of disc accreting systems.
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Cosmology and Nongalactic Astrophysics

A stringent constraint on the fractional change of proton g-factor

Renzhi Su, Stephen J. Curran, Jeremy Darling et al. (+5 more)

We report a constraint on the cosmological variation of the proton g-factor, $g_p$. By comparing the measured redshifts between \mbox{H\,i} 21 cm and OH 18 cm lines observed with the newly commissioned Five-hundred-meter Aperture Spherical radio Telescope (FAST) toward PKS 1413+135 at $z$ = 0.24671, we obtain $\Delta g_{p}/g_{p} = (-4.3\pm2.5)\times10^{-5}$, which is more than two orders of magnitude more sensitive than previous constraints. In addition, we obtain sensitive constraints of $\Delta (\mu\alpha^{2})/(\mu\alpha^{2}) = (2.0\pm1.2)\times10^{-5}$ and $\Delta (\mu\alpha^{2}g_{p}^{0.64})/(\mu\alpha^{2}g_{p}^{0.64}) = (-4.7\pm1.9)\times10^{-6}$.
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All authors Renzhi Su, Stephen J. Curran, Jeremy Darling, Minfeng Gu, J. N. H. S. Aditya, Ningyu Tang, Di Li, Zheng Zheng

High Energy Astrophysical Phenomena

Revisiting $\gamma$-Ray Orbital Modulation in the Redback Millisecond Pulsar PSR J2039-5617

Mengqing Zhang, Shengbin Pei, Shan Chang et al. (+1 more)

PSR J2039-5617 is a redback millisecond pulsar binary system consisting of a compact star with a mass of 1.1-1.6 $M_\odot$ and a low-mass companion of 0.15-0.22 $M_\odot$. For this binary, we performed a timing analysis using 16 years of data from the Fermi Large Area Telescope, covering the period from 2008 August to 2024 October. Our analysis detected an orbital modulation with a period of 0.2279781 days at a significance level of $\sim4\sigma$, which is in good agreement with previous findings. However, unlike previous reports, we identified a transition in the orbital modulation around 2021 August, after which the orbital signal disappeared. We speculate that the system may be undergoing a transition from a rotation-powered to an accretion-powered state at this epoch. Additionally, we conducted the phase-resolved and spectral analyses, and in the phase-resolved results, we observed an anti-correlation between its $\gamma$-ray and X-ray emissions, which consistent with the predictions of high-energy radiation models for such systems. We provide some predictive discussions based on the results of $\gamma$-ray data analysis, and future Fermi-LAT observations will determine whether these predictions hold true.
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All authors Mengqing Zhang, Shengbin Pei, Shan Chang, Pengfei Zhang

Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

Wave Front Sensing demodulated at the difference frequency between two phase-modulation sidebands in a compound interferometer configuration for a gravitational-wave detector

Chiaki Hirose, Kenta Tanaka, Osamu Miyakawa et al. (+1 more)

Precise alignment sensing and control are essential for maintaining the stability of laser interferometric gravitational-wave detectors. Conventional Wave Front Sensing technique (WFS), which relies on the beat between the carrier and phase-modulated (PM) sidebands, is dominated by arm-axis signals when the carrier resonates in the full interferometer. This dominance limits the detection of other optical axes, such as the Power Recycling Cavity (PRC) and incident beam axes. To address this problem, we propose a novel sensing technique, "Phase-Modulated-sideband $\times$ Phase-Modulated-sideband Wave Front Sensing" (PMPMWFS), which demodulates the beat signal at the difference frequency between two anti-resonant PM sidebands. We derived the theoretical response of PMPMWFS and experimentally demonstrated it using the Power-Recycled X-arm (PRXARM) configuration of KAGRA. The results show that PMPMWFS effectively decouples angular fluctuation signals of the PRC and incident beam from those of the arm cavity and provides orthogonal signal components for the end mirror of the arm cavity. Furthermore, feedback control using PMPMWFS achieved stable interferometer locking for over one hour. These results demonstrate that PMPMWFS offers an effective sensing method for decoupling multiple alignment degrees of freedom in future gravitational-wave detectors.
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All authors Chiaki Hirose, Kenta Tanaka, Osamu Miyakawa, Takafumi Ushiba

Solar and Stellar Astrophysics

A New FU Orionis Accretion Outburst in the W5 HII Region

Lynne A. Hillenbrand, Matthew J. Graham, Mansi M. Kasliwal et al. (+9 more)

We announce a recently detected outburst that is currently only a few months old, and probably of FU Orionis type. The progenitor to the outburst was an emission-line, flat-spectrum SED young stellar object located in the W5 region, though somewhat outside the main star formation action. We present optical, near-infrared, and mid-infrared lightcurves that illustrate the quiescent state of [KAG2008] 13656 and its subsequent$\Delta r \approx -4$ mag and $\Delta J\approx -3$ mag outburst over $\sim$75 days in late-2025. Follow-up optical and near-infrared spectroscopy confirms the expected features from an FU Ori disk and outflow.
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All authors Lynne A. Hillenbrand, Matthew J. Graham, Mansi M. Kasliwal, Josiah Purdum, Jesper Sollerman, Adolfo S. Carvalho, Michael A. Kuhn, Roger Smith, Michael C.B. Ashley, Nicholas Earley, Russ R. Laher, Tracy X. Chen

Earth and Planetary Astrophysics

Resonant structures in exozodiacal clouds created by exo-Earths in the habitable zone of late-type stars

Seung-Yoo Lee, Masateru Ishiguro, Hangbin Jo et al. (+1 more)

Earth-like exoplanets can create resonant structures in exozodiacal dust through mean motion resonances (MMRs). These structures not only suggest the presence of such planets, but also act as potential noise sources in future mid-infrared (MIR) nulling interferometry observations. We aim to investigate how resonant structures in exozodiacal dust vary across stellar spectral types (F4–M4), and to evaluate how stellar wind drag affects their morphology and brightness in mature planetary systems. We conducted numerical simulations of dust dynamics, extending earlier studies by including spectral type variation in stellar wind drag in addition to Poynting-Robertson (PR) drag. Our models represented systems of a few Gyr hosting an Earth-like exoplanet in the habitable zone (HZ). We produced spatially resolved maps of optical depth and thermal emission for different stellar spectral types. Our simulations showed that resonant ring structures were formed for all stellar spectral types considered. In particular, we found that stellar wind drag played a critical role in shaping dust dynamics around old M-type stars, where it could dominate over PR drag by a factor of approximately 44. This reduced the contrast of resonant rings relative to the background disk, compared to cases without spectral type variation in stellar wind. Across different spectral types, the optical depth contrast of the resonant ring increased for lower-mass stars, assuming a fixed background level. Asymmetric thermal emission distributions were derived across all spectral types, which peaked for K-type stars. Our findings highlight the importance of incorporating both resonant dynamics and stellar wind effects when modeling exozodiacal dust around stars of different spectral types.
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All authors Seung-Yoo Lee, Masateru Ishiguro, Hangbin Jo, Sung-Chul Yoon

Cosmology and Nongalactic Astrophysics

Prospects for measuring the Doppler magnification dipole with LSST and DESI

Isabelle Ye, Philip Bull, Caroline Guandalin et al. (+2 more)

We forecast the detectability of the Doppler magnification dipole with a joint analysis of galaxy spectroscopic redshifts and size measurements. The Doppler magnification arises from an apparent size variation caused by galaxies' peculiar velocities when mapping them from redshift space to real space. This phenomenon is the dominant contribution to the convergence at low redshifts ($\lesssim$ 0.5). A practical observational strategy is to cross-correlate a galaxy number count tracer, e.g. from the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey, with the convergence field reconstructed from galaxy size measurements obtained by the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). To assess the achievable precision of galaxy size measurements, we simulate LSST Y1-quality galaxy images with Galsim and measure them with the Galight profile fitting package. Our investigations, based on galaxy populations from LSST's synthetic galaxy catalogue cosmoDC2, show that the variance due to intrinsic galaxy size variation dominates over size measurement errors as expected, but may be lower than previous studies have suggested. Under our analysis assumptions, the Doppler magnification dipole would be detectable with a signal-to-noise ratio $\geq 10$ in multiple redshift bins between $0.1 \leq z \leq 0.5$ with DESI spectroscopic redshifts and LSST imaging.
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All authors Isabelle Ye, Philip Bull, Caroline Guandalin, Chris Clarkson, Ainulnabilah Nasirudin

Friday 21 November

Instrumentation and Methods for Astrophysics

Measuring Cometary Nuclei Behind Bright Comae: PSF Delta Decomposition with Bicubic Resampling and an Application to Interstellar Comet 3I/ATLAS C/2025 N1

Toni Scarmato

Measuring cometary nuclei is notoriously difficult because they are usually unresolved and embedded within bright comae, which hampers direct size measurements even with space telescopes. We present a practical, instrumental method that, stabilises the inner core through bicubic resampling, performs forward point-spread function PSF+convolution, and separates the unresolved nucleus from the inner-coma profile via an explicit Dirac Delta function added to a Rho^-1 surface brightness law. The method yields the nucleus flux by fitting an azimuthal averaged profile with two amplitudes only PSF core and convolved coma, with transparent residual diagnostics. As a case study, we apply the workflow to the interstellar comet 3I/ATLAS alias C/2025 N1, incorporating Hubble Space Telescope constraints on the nucleus size. We find that radius solutions consistent with 0.16 <= Rn <= 2.8 km for Pv = 0.04 are naturally recovered, in line with the most recent HST upper limits. The approach is well-suited for survey pipelines Rubin LSST and targeted follow up.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

$\mathbb Z_2$-Stable Dark Matter via Broken $\text{SU}(5)$ Gauge Bosons

E. J. Thompson

I construct and analyze a dark matter sector that is neutral under the unbroken Standard Model gauge group and couples only to the broken $\text{SU}(5)$ gauge directions, the leptoquark vectors $X,Y$. An exact $\mathbb Z_2$ renders the dark matter stable. I give a gauge-covariant definition of projectors onto the unbroken Standard Model and broken ($X,Y$) subspaces, demonstrate that the covariant derivative of dark matter selects only $X,Y$, and integrate out $X,Y$ at tree level to obtain the leading effective operators. I also derive the loop-induced $\chi^2\,G^a_{\mu\nu}G^{a\mu\nu}$ coupling to gluons, prove color neutrality, and show consistency with cold dark matter phenomenology. Cosmological production proceeds via UV freeze-in or even more suppressed channels in.
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Earth and Planetary Astrophysics

Synchronisation of a tidal binary by inward orbital migration. The case of Pluto and Charon

Michael Efroimsky, Michaela Walterova, Yeva Gevorgyan et al. (+3 more)

It is usually taken for granted that mutual synchronisation of a tidal two-body system is attained through tidal recession, assuming the reduced Hill sphere is not reached. However, synchronisation can be achieved also via tidal approach, provided the Roche limit is not crossed. For each of the two scenarios, we derive the condition under which the evolving synchronicity radius catches up with the tidally evolving orbit. We consider the two scenarios for the Pluto-Charon system and examine the impact-origin hypothesis of Charon's formation against capture. Based on geophysical evidence, we propose that capture appears more likely. Motivated by this conclusion, we investigate the capture scenario, wherein the orbital evolution of Charon starts at a larger distance than present and undergoes tidal descent, both analytically and numerically. We also consider the possibility that Pluto's initial prograde spin underwent a reversal by a tidally approaching retrograde Charon. Depending on the initial conditions, we observe temporary locking of Charon into higher spin-orbit resonances (3:2 to 7:2) during the first 0.5 Myr of the system's evolution. Owing to a greater initial separation between the partners, the power dissipated in each of them turns out to be much lower than in the case of tidal recession of bodies of the same internal structure. The greater initial separation also results in lower tidal stress, which may explain the absence of tidally generated fracture patterns.
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All authors Michael Efroimsky, Michaela Walterova, Yeva Gevorgyan, Amirhossein Bagheri, Valeri V. Makarov, Amir Khan

Solar and Stellar Astrophysics

TIC 322208686: An Eclipsing System with $\gamma$ Doradus Pulsations and a Third Component on a Wider Orbit

Jae Woo Lee, Kyeongsoo Hong, Min-Ji Jeong et al. (+3 more)

TIC 322208686 is known to be a detached binary that exhibits two types of variability: pulsation and eclipse. We present the physical properties of the target star using the short-cadence TESS data from sectors 24, 57, and 58, and our echelle spectra that show the presence of a tertiary companion. The spectral analysis led to the triple-lined radial velocities and the atmospheric parameters of the eclipsing components. Joint modeling of these observations reveals that the eclipsing pair contains two F-type stars with masses $1.564\pm0.012$ $M_\odot$ and $1.483\pm0.012$ $M_\odot$, radii $1.588\pm0.011$ $R_\odot$ and $1.500\pm0.012$ $R_\odot$, effective temperatures $7028\pm100$ K and $7020\pm110$ K, and luminosities $5.51\pm0.32$ $L_\odot$ and $4.90\pm0.32$ $L_\odot$. The light contributions of the three stars obtained from this modeling match well with those calculated from the observed spectra. The binary star parameters are in satisfactory agreement with evolutionary model predictions for age $t$ = 0.4 Gyr and metallicity $Z$ = 0.03. We extracted 11 significant frequencies from the TESS light residuals with the binary effects removed. Of these, five signals between 0.65 day$^{-1}$ and 1.89 day$^{-1}$ can be considered as $\gamma$ Dor pulsations originating mainly from the primary component, while the other frequencies are likely instrumental artifacts or combination terms. These results suggest that TIC 322208686 is a hierarchical triple, containing a pulsating eclipsing pair and a tertiary companion.
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All authors Jae Woo Lee, Kyeongsoo Hong, Min-Ji Jeong, Jang-Ho Park, Pakakaew Rittipruk, Hye-Young Kim

Astrophysics of Galaxies

An Overabundance of Radio-AGN in the SPT2349-56 Protocluster: Preheating the Intra-Cluster Medium

Scott C. Chapman, Roger P. Deane, Dazhi Zhou et al. (+22 more)

Following the detection of a radio-loud Active Galactic Nucleus (AGN) in the z=4.3 protocluster SPT2349-56, we have obtained additional observations with MeerKAT in S-band (2.4 GHz) with the aim of further characterizing radio emission from amongst the ~30 submillimeter (submm) galaxies (SMGs) identified in the structure. We newly identify three of the protocluster SMGs individually at 2.4GHz as having a radio-excess, two of which are now known to be X-ray luminous AGN. Two additional members are also detected with radio emission consistent with their star formation rate (SFR). Archival MeerKAT UHF (816 MHz) observations further constrain luminosities and radio spectral indices of these five galaxies. The Australia Telescope Compact Array (ATCA) is used to detect and resolve the central two sources at 5.5 and 9.0 GHz finding elongated, jet-like morphologies. The excess radio luminosities range from L1.4,rest = (1-20)x10^25 W/Hz, ~10-100x higher than expected from the SFRs, assuming the usual far-infrared-radio correlation. Of the known cluster members, only the SMG `N1' shows signs of AGN in any other diagnostics, namely a large and compact excess in CO(11-10) line emission. We compare these results to field samples of radio sources and SMGs. The overdensity of radio-loud AGN in the compact core region of the cluster may be providing significant heating to the recently discovered nascent intra-cluster medium (ICM) in SPT2349-56.
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All authors Scott C. Chapman, Roger P. Deane, Dazhi Zhou, Manuel Aravena, William Rasakanya, Melanie Archipley, James Burgoyne, Jared Cathey, Anthony H. Gonzalez, Ryley Hill, Chayce Hughes, Monica Natalia Isla Llave, Matt Malkan, Kedar A. Phadke, Vismaya Pillai, Ana Posses, Bonnie Slocombe, Manuel Solimano, Justin Spilker, Nikolaus Sulzenauer, Fabio Vito, Joaquin D. Vieira, David Vizgan, George Wang, Axel Weiss

High Energy Astrophysical Phenomena

Broadband X-ray observations of the periodic optical source ZTF J185139.81+171430.3 and its identification as a massive intermediate polar

Ren Deng, Kaya Mori, Eric Miao et al. (+5 more)

We present X-ray observations of the periodic optical source ZTF J185139.81+171430.3 (hereafter ZTF J1851) by the XMM, NICER and NuSTAR telescopes. The source was initially speculated to be a white dwarf (WD) pulsar system due to its short period ($P\sim12$ min) and highly-modulated optical lightcurves. Our observations revealed a variable X-ray counterpart extending up to 40 keV with an X-ray luminosity of $L_X \sim 3\times10^{33}$ erg s$^{-1}$ (0.3–40 keV). Utilizing timing data from XMM and NICER, we detected a periodic signal at $P_{\rm spin}=12.2640(7)\pm0.0583$ min with $>6\sigma$ significance. The pulsed profile displays $\sim 25\%$ and $\sim10\%$ modulation in the 0.3–2 and 2–10 keV bands, respectively. Broadband X-ray spectra are best characterized by an absorbed optically-thin thermal plasma model with $kT \approx 25$ keV and a Fe K-$\alpha$ fluorescent line at 6.4 keV. The bright and hard X-ray emission rules out the possibility of a WD pulsar or ultra-compact X-ray binary. The high plasma temperature and Fe emission lines suggest that ZTF J1851 is an intermediate polar spinning at 12.264 min. We employed an X-ray spectral model composed of the accretion column emission and X-ray reflection to fit the broadband X-ray spectra. Assuming spin equilibrium between the WD and the inner accretion disk, we derived a WD mass range of $M_{\rm WD}=(1.07\rm{-}1.32)M_{\odot}$ exceeding the mean WD mass of IPs ($\langle M_{\rm WD} \rangle = 0.8 M_\odot)$. Our findings illustrate that follow-up broadband X-ray observations could provide unique diagnostics to elucidate the nature of periodic optical sources anticipated to be detected in the upcoming Rubin all-sky optical surveys.
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All authors Ren Deng, Kaya Mori, Eric Miao, Gabriel Bridges, Charles J. Hailey, David A. H. Buckley, Gavin Ramsay, Dan Jarvis

Instrumentation and Methods for Astrophysics

The Northern High Time Resolution Universe pulsar survey: II. Single-pulse search set-up and simulations

L.J.M. Houben, H. Falcke, L.G. Spitler et al. (+5 more)

The High Time Resolution Universe (HTRU) survey is an all-sky survey looking for pulsars and other radio transients. A new single-pulse (SP) search pipeline is presented, tailored to the northern part of the HTRU survey collected with the 100m Effelsberg Radio Telescope. In a selection of this data, synthetic SPs are injected with frequency-time structures resembling those of the detected Fast Radio Burst (FRB) population and processed by the pipeline to characterize its performance. Therefore, several new software toolkits have been developed (FRBfaker and RFIbye) to enable the injection of SPs with complex frequency-time structures and cope with the Radio Frequency Interference (RFI) in the survey's data. The operation of these toolkits is described alongside the overall functionality of the SP pipeline. Qualification of the pipeline confirmed that it is ready to process all the HTRU-North data. Additionally, the survey's sensitivity to SPs, the impact of RFI thereon, the performance of the deep-learning classifier FETCH, and some insights that may be used to improve the pipeline's performance in the future are determined. Within the small data sample analysed, 21 known pulsars and a RRAT are detected. In addition, eight faint SP trains that might originate from yet undiscovered neutron stars and 141 isolated SP candidates were discovered.
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All authors L.J.M. Houben, H. Falcke, L.G. Spitler, E.D. Barr, M. Berezina, D.J. Champion, R. Karuppusamy, M. Kramer

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

The $\mu$-deformed Einstein field equations with $\mu$-dependent effective cosmological constant

O.P. Mykhailiv, Yu.A. Mishchenko and A.M. Gavrilik

In this paper, we derive the $\mu$-deformed Einstein field equations from the generalized thermodynamic functions of the $\mu$-deformed analog of Bose gas model, applying the (adapted) Verlinde's approach. The basic role of deformation parameter is shown: it provides the possibility to vary the value of the cosmological constant. Due to this, we suggest an interesting treatment of the cosmological constant (CC) problem within the framework of $\mu$-deformation. Namely, viewing the derived $\mu$-deformed CC as an effective one and varying the parameter $\mu$ appropriately, we gain the possibility to drastically reduce the CC, so as to get for it the realistic value. The relation to dark matter is of importance.
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High Energy Astrophysical Phenomena · Cross-listed from physics.ins-det

WavePID: Studies of DOM-level waveform timing for track vs. cascade discrimination in IceCube at 5-100 GeV

Steven Young Eulig

The IceCube Neutrino Observatory is a cubic-kilometer Cherenkov detector embedded in the Antarctic ice at the South Pole. Its densely instrumented sub-array and dedicated low-energy analyses provide sensitivity to neutrinos in the 5-100 GeV range, enabling precision studies of neutrino oscillations and searches for new physics. This work focuses specifically on this low-energy regime, where sparse hit patterns limit the performance of topology-based reconstruction and classification methods. We introduce Waveform-based Particle Identification (WavePID), a statistically rigorous and interpretable likelihood-ratio discriminator for track-cascade separation, built from Monte Carlo templates in timing-aware, physics-motivated observables and validated through dedicated simulations. Applied to both Monte Carlo and 11.1 years of IceCube data, WavePID suggests improved cascade purity by about 5 percentage points at a fixed 20% down-selection rate relative to the current leading cascade selection, while maintaining Data-MC agreement within detector systematics. The approach is compact and robust to sparse observations, demonstrating the value of waveform-level timing for low-energy reconstruction.
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Solar and Stellar Astrophysics

Outflow Interaction in Cep-E: Numerical Simulation and Observational Manifestation

A. Rodríguez-González, P. R. Rivera-Ortiz, Z. Meliani et al. (+3 more)

There is clear observational evidence that the main Class 0/I stages of the star formation process are associated with powerful collimated outflows (jets), which sometimes propagate up to distances as large as $10^{4-5}$ au scales in molecular clouds. Additionally, intermediate high-mass and low-mass protostars have often been observed to form in crowded clusters, where the typical separation distance between any two cluster members is of the same order or smaller than the scale of the outflow length. Therefore, there must be an interaction between the molecular outflows of different protostars within the protostellar association. A good example of this is the case of Cepheus E-mm, which is a protostellar outflow extending over a few dozen au. At its core is a binary system consisting of two protostars, Cep E-A and Cep E-B, separated by about 1000 au. Both protostars eject molecular jets at velocities of ~100 km/s. The interaction between these molecular outflows provides an opportunity to study the effects of jet collisions in a clustered star-forming environment, as they may leave detectable imprints on the morphology of the main envelope of the system. Our work aims to study the effects of the collision of molecular jets associated with the components of the binary system Cep-A and Cep-E, analyzing the disruption or reduction of molecular emission in the main envelope of the system, which the molecular outflow { launched} by Cep-A presumably pushes. If we characterize the collision in this system, we can provide insights into the expected morphology and molecular emissions in collisions of molecular outflows { associated to star forming process.
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All authors A. Rodríguez-González, P. R. Rivera-Ortiz, Z. Meliani, E. Alquicira-Peláez, A. Durán, Luis A. Zapata

High Energy Astrophysical Phenomena

The Optical Evolution of the Tycho Supernova Remnant over Three Decades

P. Frank Winkler, Joseph Putko and William P. Blair

We report a series of images of the Tycho supernova remnant at eight epochs extending over thirty years: 1986-2016. In addition to our H{\alpha} images, we have obtained matched continuum images which we subtract to reveal faint emission, including a far more extensive network of optical knots and filaments than reported previously. The deepest images also show an extremely faint, fairly diffuse arc of emission surrounding much of the circumference of Tycho to the southeast and south, coinciding with the rim of the radio/X-ray shell. We have measured proper motions for 46 filaments, including many fainter ones near the Tycho outer rim. Our measurements are generally consistent with previous ones by Kamper and vandenBergh (1978), but ours have far greater precision. Most optical filaments at the shell rim have expansion indices reasonably consistent with the Sedov value (0.40), while the interior filaments have somewhat smaller values, as expected. From the combination of proper motions of filaments at the shell rim and shock velocity at the same positions, one should be able to calculate the distance to Tycho by simple geometry. Determination of the shock velocity from broad Balmer-line profiles is subject to model uncertainties, but the availability of dozens of such filaments with a range of conditions offers the possibility to substantially improve the distance determination for Tycho.
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Astrophysics of Galaxies

JADES: Low Surface Brightness Galaxies at 0.4 < z < 0.8 in GOODS-S

Tristen Shields, Marcia Rieke, Kevin Hainline et al. (+11 more)

Low surface brightness galaxies (LSBs) are an important class of galaxies that allow us to broaden our understanding of galaxy formation and test various cosmological models. We present a survey of low surface brightness galaxies at $0.4 < z_{\rm phot} < 0.8$ in the GOODS-S field using JADES data. We model LSB surface brightness profiles, identifying those with $\bar{\mu}_{\rm eff} > 24$ mag arcsec$^{-2}$ in the F200W JWST/NIRCam filter. We study the spatial distribution, number density, Sérsic profile parameters, and rest-frame colours of these LSBs. We compare the photometrically-derived star formation histories, mass-weighted ages, and dust attenuations of these galaxies with a high surface brightness (HSB) sample at similar redshift and a lower redshift ($z_{\rm phot} < 0.4$) LSB sample, all of which have stellar masses $\lesssim 10^8 M_{\odot}$. We find that all samples have low star formation (SFR$_{100} \lesssim 0.01$ $M_{\odot}$ yr$^{-1}$). The higher redshift LSBs and HSBs have similar star formation histories which show that the LSBs and HSBs possibly come from the same progenitors at $z \gtrsim 2$, though the histories are not well constrained for the LSB samples. The LSBs appear to have minimal dust, with most of our LSB samples showing $A_V < 1$ mag. JWST has pushed our understanding of LSBs beyond the local Universe.
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All authors Tristen Shields, Marcia Rieke, Kevin Hainline, Jakob M. Helton, Andrew J. Bunker, Courtney Carreira, Emma Curtis-Lake, Daniel J. Eisenstein, Benjamin D. Johnson, Pierluigi Rinaldi, Brant Robertson, Christina C. Williams, Christopher N.A. Willmer, Yang Sun

Cosmology and Nongalactic Astrophysics

Neural posterior estimation of the line-of-sight and subhalo populations in galaxy-scale strong lensing systems

Birendra Dhanasingham, Francis-Yan Cyr-Racine and Daniel Gilman

Strong gravitational lensing is a powerful probe for studying the fundamental properties of dark matter on sub-galactic scales. Detailed analyses of galaxy-scale lenses have revealed localized gravitational perturbations beyond the smooth mass distribution of the main lens galaxy, largely attributed to dark matter subhalos and intervening line-of-sight halos. Recent studies suggest that, in contrast to subhalos, line-of-sight halos imprint distinct anisotropic features on the two-point correlation function of the effective lensing deflection field. These anisotropies are particularly sensitive to the collisional nature of dark matter, offering a potential means to test alternatives to the cold dark matter paradigm. In this study, we explore whether a neural density estimator can directly identify such anisotropic signatures from galaxy-galaxy strong lens images. We model the multipoles of the two-point function using a power-law parameterization and train a neural density estimator to predict the corresponding posterior distribution of lensing parameters, alongside parameter distributions for dark matter substructure. Our results show that recovering the dark matter substructure mass functions and mass-concentration parameters remains challenging, owing to difficulties in generating uniform training data set while using physically motivated priors. We also unveil an important degeneracy between the line-of-sight halo mass-function amplitude and the subhalo mass-function normalization. Furthermore, the network exhibits limited accuracy in predicting the two-point function multipole parameters, suggesting that both the training data and the adopted power-law fitting function may inadequately represent the true underlying structure of the anisotropic signal.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.RO

Vision-Guided Optic Flow Navigation for Small Lunar Missions

Sean Cowan, Pietro Fanti, Leon B. S. Williams et al. (+4 more)

Private lunar missions are faced with the challenge of robust autonomous navigation while operating under stringent constraints on mass, power, and computational resources. This work proposes a motion-field inversion framework that uses optical flow and rangefinder-based depth estimation as a lightweight CPU-based solution for egomotion estimation during lunar descent. We extend classical optical flow formulations by integrating them with depth modeling strategies tailored to the geometry for lunar/planetary approach, descent, and landing, specifically, planar and spherical terrain approximations parameterized by a laser rangefinder. Motion field inversion is performed through a least-squares framework, using sparse optical flow features extracted via the pyramidal Lucas-Kanade algorithm. We verify our approach using synthetically generated lunar images over the challenging terrain of the lunar south pole, using CPU budgets compatible with small lunar landers. The results demonstrate accurate velocity estimation from approach to landing, with sub-10% error for complex terrain and on the order of 1% for more typical terrain, as well as performances suitable for real-time applications. This framework shows promise for enabling robust, lightweight on-board navigation for small lunar missions.
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All authors Sean Cowan, Pietro Fanti, Leon B. S. Williams, Chit Hong Yam, Kaneyasu Asakuma, Yuichiro Nada, Dario Izzo

Earth and Planetary Astrophysics

Evidence of 1:1 slope between rocky Super-Earths and their host stars

Mykhaylo Plotnykov, Diana Valencia, Alejandra Ross et al. (+2 more)

The relationship between the composition of rocky exoplanets and their host stars is fundamental to understanding planetary formation and evolution. However, previous studies have been limited by inconsistent datasets, observational biases and methodological differences. This study investigates the compositional relationship between rocky exoplanets and their host stars, utilizing a self-consistent and homogeneous dataset of 21 exoplanets and their 20 host stars. By applying sophisticated interior structure modeling and comprehensive chemical analysis, we identify a potential 1:1 best-fit line between the iron-mass fraction of planets and their host stars equivalent with a slope of $m = 0.94^{+1.02}_{-1.07}$ and intercept of $c = -0.02^{+0.31}_{-0.29}$. This results are consistent at the 1$\sigma$ level with other homogeneous studies, but not with heterogeneous samples that suggest much steeper best-fit lines. Although, our results remain tentative due to sample size and data uncertainties, the updated dataset significantly reduces the number of super-Mercuries from four to one, but it remains that several high-density planets are beyond what a primordial origin would suggest. The planets in our sample have a wider range of compositions compared to stellar equivalent values, that could indicate formation pathways away from primordial or be the result of random scattering owing to current mass-radius uncertainties as we recover the observed outliers in mock population analysis $\sim15\%$ of the time. To truly determine whether the origin is primordial with a 1:1 true relation, we find that sample of at least 150 planets is needed and that stars that are iron enrich or depleted are high value targets.
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All authors Mykhaylo Plotnykov, Diana Valencia, Alejandra Ross, Henrique Reggiani, Kevin C. Schlaufman

Astrophysics of Galaxies

PROJECT-J: the shocking H2 outflow from HH46

Maria Gabriela Navarro, Brunella Nisini, Teresa Giannini et al. (+14 more)

We analyze the H2 emission observed in the HH46 Class I system as part of PROJECT-J (Protostellar Jets Cradle Tested with JWST), to investigate the origin and excitation of the warm molecular outflow. We used NIRSpec and MIRI spectral maps (1.6-27.9 microns) to trace the structure and physical conditions of the outflow. By fitting the H2 rotational diagrams with a multi-temperature gas model, we derived key physical parameters including temperature, extinction, column densities, and the ortho-to-para ratio. This information is combined with a detailed kinematical analysis and comparison with irradiated shock models. We find no evidence of H2 temperature or velocity stratification from the axis to the edge of the outflow, as would be expected in MHD disk-wind models and as observed in other outflows. Instead, the observations suggest that the H2 emission arises from shock interactions between jet bow shocks and/or wide-angle winds with the ambient medium and cavity walls. NIRSpec emission and velocity maps reveal expanding molecular shells, likely driven by the less luminous source in the binary system. We infer an accretion rate of less than 10^-9 solar masses per year for the secondary source, approximately one order of magnitude lower than that of the primary. The H2 emission is consistent with excitation by low-velocity (approximately 10 km/s) J-type shocks, irradiated by an external UV field that may originate from strong dissociative shocks driven by the atomic jet. Future JWST observations will further constrain the evolution of the expanding shell and the mechanisms driving the outflow.
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All authors Maria Gabriela Navarro, Brunella Nisini, Teresa Giannini, Patrick J. Kavanagh, Alessio Caratti o Garatti, Simone Antoniucci, Hector G. Arce, Francesca Bacciotti, Sylvie Cabrit, Deirdre Coffey, Catherine Dougados, JJochen Eislöffel, Patrick Hartigan, Alberto Noriega-Crespo, Linda Podio, Ewine F. van Dishoeck, Emma T. Whelan