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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 29 October

High Energy Astrophysical Phenomena

Spherically Symmetric Quantum-Corrected Black Holes with String Clouds: A Multi-Observable Analysis

Faizuddin Ahmed, Ahmad Al-Badaw, Orhan Donmez et al. (+4 more)

We present an investigation of quantum-corrected black hole spacetimes coupled with clouds of strings, examining two distinct theoretical models that incorporate quantum gravitational effects through different implementations of correction terms. Our study explores the geodesic structure, focusing on photon sphere properties, black hole shadows, and innermost stable circular orbits of test particles around these exotic geometries. The analysis reveals fundamental modifications to particle trajectories that distinguish quantum-corrected solutions from their classical counterparts, with observable implications for high-energy astrophysics. We investigate quasi-periodic oscillations arising from test particle motion, deriving frequency relationships that could serve as observational probes of quantum gravity effects in accreting black hole systems. Through rigorous gravitational lensing analysis using the Gauss-Bonnet theorem, we calculate weak-field deflection angles and identify distinctive signatures that enable discrimination between the two quantum correction models. The gravitational lensing study reveals opposite dependencies on quantum parameters between the models, providing unambiguous observational discriminants. Additionally, we analyze the thermodynamic properties including temperature, entropy, and heat capacity modifications, exploring topological characteristics and phase transition behavior in these quantum-corrected systems. The investigation reveals that the two models exhibit contrasting behaviors across multiple observational channels, from gravitational lensing deflection angles to quasi-periodic oscillation frequencies, providing remarkable discriminants for testing quantum gravity theories.
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All authors Faizuddin Ahmed, Ahmad Al-Badaw, Orhan Donmez, Izzet Sakalli, Saeed Noori Gashti, Behnam Pourhassan, Fatih Dogan

High Energy Astrophysical Phenomena

Radiation-dominated polar emitting region of an accreting X-ray pulsar – I. Polarization- and spectrum-dependent structure, and the emergent continuum

M. I. Gornostaev

The radiation-dominated polar emitting region of an accreting X-ray pulsar is simulated numerically in the framework of a three-dimensional (geometrically two-dimensional) model. The radiative transfer within the emitting region and the structure of the latter are calculated with the use of the self-consistent algorithm developed earlier. The magnetic scattering cross sections dependent on the photon energy and polarization have been incorporated. Second-order bulk Comptonization over entire emitting region, induced Compton scattering, the switching of the polarization modes, free-free processes, the cyclotron emission because of electron-proton collisions, and a realistic shape of the accretion channel have been taken into account. The case of a dipole magnetic field is considered. It is shown that the induced Compton effect can play a notable role in establishing the electron temperature in the post-shock zone. Within the model shock wave, a higher electron temperature is achieved than in the post-shock zone by means of the bulk-heating mechanism. The photons gaining the energy in the shock wave and above it due to bulk motion effects and the thermal Doppler effect are responsible for the formation of high-energy regions in the emergent continuum of the polarization modes.
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Astrophysics of Galaxies

RIOJA. Young Starburst and Ionized Gas Outflows in a $z = 7.212$ Galaxy Uncovered by JWST NIRCam and NIRSpec Observations

Yi W. Ren, Akio K. Inoue, Javier Álvarez-Márquez et al. (+21 more)

We present analysis of JWST NIRCam and NIRSpec observations of the galaxy SXDF-NB1006-2 at $z = 7.212$, as part of the Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA) project. We derive the physical properties by conducting spectral energy distribution (SED) fitting, revealing that our target is a young (age $\sim2$ Myr) starburst galaxy with intense radiation field. We detect multiple nebular emission lines from NIRSpec IFS data. We identify a robust broad component of [O III]$\lambda5008$ emission, indicating the presence of ionized gas outflows. The derived gas depletion time of a few hundred Myr implies that our target could be one of the progenitors of massive quiescent galaxies at $z\sim4-5$ identified by recent JWST observations. The spatial distribution of optical and far-infrared (FIR) [O III] emission lines differs in morphology, likely resulting from different critical densities and inhomogeneous density distributions within the galaxy. Potential old stellar populations may be necessary to account for the derived metallicity of $\sim0.2\,\rm{Z}_\odot$, and their presence can be confirmed by future MIRI observations. Including our target, star-forming galaxies at $z>6$ detected by ALMA are generally very young but more massive and brighter in UV than galaxies identified by only JWST. The ALMA-detected galaxies may also have a steeper mass-metallicity relation. These findings suggest that the ALMA-detected galaxies may have experienced more efficient mass assembly processes in their evolutionary pathways.
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All authors Yi W. Ren, Akio K. Inoue, Javier Álvarez-Márquez, Takuya Hashimoto, Luis Colina, Yuma Sugahara, Luca Costantin, Ken Mawatari, Yoshinobu Fudamoto, Santiago Arribas, Alejandro Crespo Gómez, Daniel Ceverino, Yurina Nakazato, Masato Hagimoto, Mitsutaka Usui, Rui Marques-Chaves, Hiroshi Matsuo, Takeshi Hashigaya, Wataru Osone, Carmen Blanco-Prieto, Yoichi Tamura, Naoki Yoshida, Tom J. L. C. Bakx, Miguel Pereira-Santaella

Instrumentation and Methods for Astrophysics · Cross-listed from nucl-ex

End-to-End Data Analysis Methods for the CUORE Experiment

D. Q. Adams, C. Alduino, K. Alfonso et al. (+117 more)

The Cryogenic Underground Observatory for Rare Events (CUORE) experiment set the most stringent limit on the neutrinoless double-beta ($0\nu\beta\beta$) decay half-life of $^{130}$Te with 2 ton yr TeO$_2$ analyzed exposure. In addition to $0\nu\beta\beta$ decay, the CUORE detector – a ton-scale array of nearly 1000 cryogenic calorimeters operating at $\sim$10 mK – is capable of searching for other rare decays and interactions over a broad energy range. For our searches, we leverage the available information of each calorimeter by performing its optimization, data acquisition, and analysis independently. We describe the analysis tools and methods developed for CUORE and their application to build high-quality datasets for numerous physics searches. In particular, we describe in detail our evaluation of the energy-dependent detector response and signal efficiency used in the most recent search for $0\nu\beta\beta$ decay.
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All authors D. Q. Adams, C. Alduino, K. Alfonso, A. Armatol, F. T. Avignone III, O. Azzolini, G. Bari, F. Bellini, G.Benato, M. Beretta, M. Biassoni, A. Branca, C. Brofferio, C. Bucci, J. Camilleri, A. Caminata, A. Campani, J. Cao, C. Capelli, S.Capelli, L. Cappelli, L. Cardani, P. Carniti, N. Casali, E. Celi, D. Chiesa, M. Clemenza, S. Copello, O. Cremonesi, R. J.Creswick, A. D'Addabbo, I. Dafinei, S. Dell'Oro, S. Di Domizio, S. Di Lorenzo, T. Dixon, D. Q. Fang, M. Faverzani, E. Ferri, F.Ferroni, E. Fiorini, M. A. Franceschi, S. J. Freedman, S.H. Fu, B. K. Fujikawa, S. Ghislandi, A. Giachero, M. Girola, L. Gironi, A.Giuliani, P. Gorla, C. Gotti, P. V. Guillaumon, T. D. Gutierrez, K. Han, E. V. Hansen, K. M. Heeger, D. L. Helis, H. Z. Huang, M. T.Hurst, G. Keppel, Yu. G. Kolomensky, R. Kowalski, R. Liu, L. Ma, Y. G. Ma, L. Marini, R. H. Maruyama, D. Mayer, Y. Mei, M. N.Moore, T. Napolitano, M. Nastasi, C. Nones, E. B. Norman, A. Nucciotti, I. Nutini, T. O'Donnell, M. Olmi, B. T. Oregui, S.Pagan, C. E. Pagliarone, L. Pagnanini, M. Pallavicini, L. Pattavina, M. Pavan, G. Pessina, V. Pettinacci, C. Pira, S. Pirro, E. G.Pottebaum, S. Pozzi, E. Previtali, A. Puiu, S. Quitadamo, A. Ressa, C. Rosenfeld, B. Schmidt, R. Serino, A. Shaikina, V.Sharma, V. Singh, M. Sisti, D. Speller, P. T. Surukuchi, L. Taffarello, C. Tomei, A. Torres, J. A. Torres, K. J. Vetter, M. Vignati, S.L. Wagaarachchi, B. Welliver, J. Wilson, K. Wilson, L. A. Winslow, F. Xie, T. Zhu, S. Zimmermann, S. Zucchelli

Cosmology and Nongalactic Astrophysics

Cosmological Constraints from Dark Energy Survey Year 1 Cluster Lensing and Abundances with Simulation-based Forward-Modeling

Andrés N. Salcedo, Eduardo Rozo, Hao-Yi Wu et al. (+7 more)

We present a simulation-based forward-modeling framework for cosmological inference from optical galaxy-cluster samples, and apply it to the abundance and weak-lensing signals of DES-Y1 redMaPPer clusters. The model embeds cosmology-dependent optical selection using a counts-in-cylinders approach, while also accounting for cluster miscentering and baryonic feedback in lensing. Applied to DES-Y1, and assuming a flat $\Lambda$CDM cosmology, we obtain $\Omega_m=0.254^{+0.026}_{-0.020}$ and $\sigma_8=0.826^{+0.030}_{-0.034}$, consistent with a broad suite of low-redshift structure measurements, including recent full-shape analyses, the DES/KiDS/HSC 3$\times$2 results, and most cluster-abundance studies. Our results are also consistent with Planck, with the difference being significant at $2.58\sigma$. These results establish simulation-based forward-modeling of cluster abundances as a promising new tool for precision cosmology with Stage~IV survey data.
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All authors Andrés N. Salcedo, Eduardo Rozo, Hao-Yi Wu, David H. Weinberg, Pranav Chiploonkar, Chun-Hao To, Shulei Cao, Eli S. Rykoff, Nicole Marcelina Gountanis, Conghao Zhou

Cosmology and Nongalactic Astrophysics

A Light-Cone Approach to Higher-Order Cosmological Observables

Pierre Béchaz, Giuseppe Fanizza, Giovanni Marozzi et al. (+1 more)

We develop a second-order cosmological perturbation theory on a background geometry expressed in terms of light-cone coordinates, extending the first-order analyses available in the literature. In particular, we investigate the gauge transformations of second-order perturbative quantities on the light-cone and establish their connection with standard perturbation theory. Through a consistent matching procedure, we identify the second-order gauge fixing that corresponds to the non-linear Geodesic Light-Cone gauge within standard perturbation theory, known as the Observational Synchronous Gauge. We then emphasize its conceptual similarities and differences wrt the standard Synchronous Gauge. Finally, within this new perturbative framework, and adopting a fully gauge-invariant approach, we compute the luminosity distance-redshift relation up to second order with anisotropic stress as seen by a free-falling observer. Remarkably, we show how divergences at the observer position can be eliminated in a completely model independent way. These results validate our perturbative framework and establish it as a novel formalism for evaluating cosmological observables at second order.
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All authors Pierre Béchaz, Giuseppe Fanizza, Giovanni Marozzi, Matheus R. Medeiros Silva

Earth and Planetary Astrophysics

Engulfment of a hot Jupiter as a possible origin of the rapid spin and internal spin misalignment of the planet-hosting red giant Kepler-56

Takato Tokuno

A recent asteroseismic analysis suggests that Kepler-56 – a planet-hosting red giant – exhibits a unique spin structure: (1) the spin axes of the core and envelope are misaligned; and (2) the envelope rotates approximately an order of magnitude faster than typical red giants. In this paper, we investigate a feasible scenario to reproduce this spin structure by estimating the amount of the angular momentum (AM) supply from the planets through the simplified calculation of the time evolution of AM. As a result, unless the tidal efficiency is extremely high, we show that the tidal interactions between the known close-in planets (Kepler-56 b and c) are insufficient to supply the AM required to accelerate Kepler-56 from the spin rate observed in typical red giants. We also show that the engulfment of a hot Jupiter can be expected to provide sufficient AM supply for the acceleration ant that the mass and orbit of the engulfed hot Jupiter are constrained by a mass of 0.5-2 Jupiter masses and an orbital period of 1-6 days. On the other hand, if Kepler 56 was already rapidly spinning before entering the RG stage and requires no acceleration, the obliquity damping by the known close-in planets can reproduce the spin structure of Kepler-56. Even in such cases, planetary engulfment during the MS stage might be involved in achieving rapid spin before the tidal alignment. These discussions demonstrate the importance of Kepler-56 as a candidate for planetary engulfment that may leave traces of its spin structure.
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High Energy Astrophysical Phenomena

Identification of Large-Scale (>100 kpc) Radio Jets in Narrow-Line Seyfert 1 Galaxies

S. Umayal, Vaidehi S. Paliya, D. J. Saikia et al. (+3 more)

Powerful, large-scale relativistic jets are usually associated with massive, old elliptical galaxies. This paradigm has recently been challenged by the identification of narrow-line Seyfert 1 (NLSy1) galaxies, thought to be young active galactic nuclei with low-mass black holes, harboring relativistic jets. Among them, sources hosting $>$100 kpc radio jets are extremely rare. Here, we report the discovery of large-scale, double-lobed radio structures in 33 NLSy1s with the projected linear size of at least 100 kpc from a recently published catalog of 22656 NLSy1 galaxies. These 33 include 29 confirmed double-lobed sources and 4 candidates whose radio structure requires further study. We suggest that their low black hole masses are unlikely to be due to their small angles of inclination to the line of sight. These enigmatic sources were identified by examining the radio observations taken with the Faint Images of the Radio Sky at Twenty centimeters, Very Large Array Sky Survey, Low Frequency Array, and Rapid ASKAP Continuum Survey. Among them, the NLSy1 source J1318+2626 ($z=0.62$) is found to host a radio jet with the projected linear size of 4.3 Mpc, making it the only NLSy1 galaxy hosting a Mpc-scale radio jet known as of today. We conclude that future observations of NLSy1 sources with the next generation of sensitive telescopes may reveal a much larger population harboring large-scale jets, thus providing crucial clues on their origin, propagation, and interaction with the ambient environment.
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All authors S. Umayal, Vaidehi S. Paliya, D. J. Saikia, C. S. Stalin, S. Muneer, Maheswar Gopinathan

Cosmology and Nongalactic Astrophysics

Morphology of Inflationary Gravitational Wave Spectra imprinted by a Sequence of Post-Inflationary Epochs $via$ ${\rm GWInSpect}$

Swagat S. Mishra and Athul K. Soman

The expansion history of the Universe prior to Big Bang Nucleosynthesis (BBN) remains largely unconstrained. The high-energy post-inflationary era may involve multiple distinct epochs, each characterized by a different equation of state (EoS). A key prediction of inflation is the generation of tensor perturbations that later manifest as a stochastic background of primordial gravitational waves (GWs). The large-scale amplitude and small-scale spectral tilt ($n_{\rm GW}$) of these GWs encode the inflationary energy scale and the subsequent expansion history, respectively. A soft post-inflationary EoS ($w<1/3$) yields red-tilted GW spectra ($n_{\rm GW}<0$), while a stiff EoS ($w>1/3$) results in a blue-tilt ($n_{\rm GW}>0$). In our previous work [arXiv:2407.07956], we developed an analytical framework for computing the GW spectral energy density, $\Omega_{\rm GW}(f)$, for multiple post-inflationary transitions ($w_1 \to w_2 \to \cdots \to w_n \to 1/3$), focusing on the parameter space relevant for future GW observations. In this paper, we extend that framework to systematically investigate the $morphological~diversity$ of inflationary GW spectra generated by multi-epoch post-inflationary histories. Remaining model agnostic, we demonstrate that a wide variety of spectral shapes, ranging from convex and concave monotonic profiles to multi-peaked non-monotonic spectra, can naturally emerge depending on the sequence and duration of these epochs. We also introduce GWInSpect, a publicly available Python package that computes $\Omega_{\rm GW}(f)$ for arbitrary sequences of EoS transitions, providing a practical tool to study the pre-BBN expansion history of the Universe.
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Solar and Stellar Astrophysics

Observing Orbital Decay in the Ultracompact Hot Subdwarf Binary System ZTFJ213056.71+442046.5

Paul Teckenburg, Thomas Kupfer, Alex J. Brown et al. (+7 more)

Ultracompact Galactic binary systems (UCBs) emit low-frequency gravitational waves (GWs). The emission of GWs is causing these systems to lose angular momentum, which is detectable by observing an orbital period decay. ZTFJ213056.71+442046.5 (ZTFJ2130) is an UCB with a period of 39.3401(1) minutes consisting of a Roche lobe-filling hot subdwarf and a white dwarf companion. We attempt to measure the orbital decay rate $\dot{P}$ caused by GW emission of ZTFJ2130 and predict the expected GW signal for LISA. High-speed photometry was conducted using the FLI Kepler KL4040FI CMOS camera, mounted to the 1.2-meter Oskar Lühning telescope at the Hamburg Observatory as well as the Hamamatsu ORCA-Quest 2 qCMOS camera at the 1.23-meter telescope at CAHA in Spain. ZTFJ2130 was observed on six nights between August 2024 and September 2025. The obtained lightcurves combined with previous high-cadence observations were used to conduct an O-C timing analysis. Additionally, we employed the LISA data analysis tool ldasoft to model the expected GW data. We measure a period change of $(-1.97\pm0.05)\times10^{-12}\,\mathrm{ss^{-1}}$. Assuming only GW emission, this result was used to calculate a chirp mass of $(0.408\pm0.006)\,\mathrm{M_{\odot}}$. From ldasoft we predict that LISA will be able to measure the chirp mass with an uncertainty of 5%. We measure $\dot{P}$ with an uncertainty of only 2% and show that modern (q)CMOS detectors are well suited to provide precise timing measurements, enabling the measurement of the orbital decay of UCBs with high precision with modest size telescopes. The derived orbital decay is fully consistent with predictions from spectral and lightcurve modeling. We show that future observations with LISA can potentially provide a deviation from only gravitational wave effects, e.g. due to accretion, if the effect is sufficiently large.
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All authors Paul Teckenburg, Thomas Kupfer, Alex J. Brown, Martin M. Roth, Fatma Ben Daya, Jörg Knoche, Stella Vješnica, Paško Roje, Mike Kretlow, Stefan Cikota

Astrophysics of Galaxies

Extreme equivalent width-selected low-mass starbursts at $z=4-9$: insights into their role in cosmic reionization

M. Llerena, L. Pentericci, R. Amorín et al. (+22 more)

We investigate the properties of extreme emission line galaxies (EELGs) at $z=4-9$ and their role in reionization. Compact, low-mass galaxies with intense optical emission lines are linked to elevated specific star formation rates (sSFRs) and recent bursts of star formation. Feedback in these systems may enable the leakage of ionizing radiation into the intergalactic medium. Using JWST/NIRSpec spectroscopy from the CAPERS, CEERS, and RUBIES surveys, we compile 160 NIRCam-selected EELGs in the EGS field. These galaxies show extreme rest-frame equivalent widths (EWs), with a median EW([O III]+H${\beta}$)=1616Å and EW(H${\alpha}$)=763Å. They are low-mass (median log(M$_{\star}$/M$_{\odot}$)=8.26) with high sSFRs (median 43 Gyr$^{-1}$), above the $z\sim6$ main sequence. UV slopes are diverse, with a mean $\beta=-2.0$, and only 7% have extremely blue continua ($\beta<-2.6$). Emission-line diagnostics suggest stellar populations as the primary ionizing source, although an AGN fraction of 14% is cannot be entirely ruled out. These galaxies are efficient ionizing photon producers, with mean log($\xi_{\rm ion}$ [Hz erg$^{-1}$])=25.37, exceeding typical values at similar redshifts. Escape fractions, however, are heterogeneous: 16% of EELGs at $z<7$ show escape fractions $>$5% for both Ly${\alpha}$ and LyC photons, while 82% lack detectable Ly${\alpha}$ emission. The median inferred LyC escape fraction is modest (5%) but enhanced in compact super-Eddington systems with sSFR >25 Gyr$^{-1}$. These results indicate that EELGs contribute approximately 16-40% of the total ionizing emissivity required to sustain hydrogen reionization. EELGs are extremely compact, with a median effective radius of 0.49 kpc, and exhibit a recent star-formation burst. Our analysis indicates that sSFR and star-formation rate surface density are the primary drivers of their extreme emission line strengths.
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All authors M. Llerena, L. Pentericci, R. Amorín, A. Ferrara, M. Dickinson, F. Arevalo-Gonzalez, A. Calabrò, L. Napolitano, S. Mascia, P. Arrabal Haro, R. Begley, N. J. Cleri, K. Davis, W. Hu, J. S. Kartaltepe, A. M. Koekemoer, R. A. Lucas, E. McGrath, D. J. McLeod, C. Papovich, T. M. Stanton, A. J. Taylor, R. Tripodi, X. Wang, L. Y. A. Yung

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

Cross-correlating Astrometric and Timing Residuals to Constrain Stochastic Gravitational-Wave Backgrounds

Elias Fink, Carlo Contaldi and Giorgio Mentasti

We investigate the cross-correlation between astrometric and timing-residual observables for distant sources, such as pulsars and galaxies, and equivalent observables for nearby solar system bodies. Using the unified spin-weighted formalism introduced in [1], we derive the angular correlation functions-generalised Hellings-Downs curves-that describe the response of these mixed observables to a stochastic, unpolarised gravitational-wave background (SGWB). We compute the expected signal-to-noise ratio (SNR) and sensitivity for such measurements, focusing on cross-correlations between pulsar timing array (PTA) redshift signals and astrometric or distortion (shimmering) effects induced in solar system objects such as asteroids. Although the current astrometric precision of asteroid tracking does not yet provide competitive constraints relative to PTA-only surveys, the method offers a complementary probe with enhanced sensitivity at higher frequencies. Future wide-field surveys capable of sub-milliarcsecond precision could make this approach a viable tool for detecting or constraining the SGWB. A key advantage of the technique is its reduced susceptibility to correlated systematics across different measurement domains, providing an independent cross-check of PTA detections and a potential observational bridge between PTA and LISA frequency bands.
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Astrophysics of Galaxies

The mass-metallicity relation of bulges

Ignacio Muñoz-Escobar, Patricia B. Tissera, Jenny Gonzalez-Jara et al. (+4 more)

Context. Bulges, located at the central regions of galaxies, are complex structures, expected to be shaped by the physical processes involved in the assembly history of their host galaxy, such as gravitational collapse, mergers, interactions, and bars. As a consequence a variety of bulges with distinct morphology and chemistry could be produced. Aim. We aim at exploring the existence of a stellar mass-metallicity relation of bulges, MZ*R, and analyze the possible imprint of characteristics features by accretion and migration of stars, which could store information on their assembly histories. Methods. We use 44 central galaxies from the CIELO cosmological simulations. Their stellar masses are within the range of [10^7.6, 10^10.6] Msun. We decomposed the galaxy into bulge and disk using the circularity and binding energies. We track the stellar populations in bulges back in time to their birth location, classifying them as bulge-born in-situ, and disk-born stars and accreted. Results. We find that most of the stars in our bulges are formed in-situ, but 33% of our bulges show a non-negligible contribution of stellar accretion from satellites, which could add to about 35% of the population. The accreted material is generally contribute by two or three satellites at most. In some bulges, we also find up to a 32% of stars that migrated from the disk due to secular evolution, with a median of 10%. Regardless of the formation histories, we found a clear MZ*R for bulges, which is more enriched by about 0.4 dex than the corresponding relation of the disk components, and about 0.15 dex more enriched than the galaxy MZ*R. We find evidence that the dispersion in the bulge MZ*R is influenced by both stellar accretion from satellites and migration from the disk, such that, at a fixed bulge mass, bulges with higher fraction of accreted and migrated stars tend to be less metal-rich (abridged).
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All authors Ignacio Muñoz-Escobar, Patricia B. Tissera, Jenny Gonzalez-Jara, Emanuel Sillero, Valentina P. Miranda, Susana Pedrosa, Lucas Bignone

Solar and Stellar Astrophysics

Mode Composition Shapes Magnetic Anisotropy in Solar Wind Turbulence

Siqi Zhao, Huirong Yan, Terry Z. Liu et al. (+1 more)

Turbulence is a ubiquitous process that transfers energy across many spatial and temporal scales, thereby influencing particle transport and heating. Recent progress has improved our understanding of the anisotropy of turbulence with respect to the mean magnetic field; however, its exact form and implications for magnetic topology and energy transfer remain unclear. In this study, we investigate the nature of magnetic anisotropy in compressible magnetohydrodynamic (MHD) turbulence within low-$\beta$ solar wind using measurements from the Cluster spacecraft. By decomposing small-amplitude fluctuations into Alfvén and compressible modes, we reveal that magnetic anisotropy is largely mode dependent: Alfvenic fluctuations are broadly distributed in propagation angle, whereas compressible fluctuations are concentrated near the quasi-parallel (slab) direction, a feature closely linked to collisionless damping of compressible modes. For $\beta\rightarrow0$, compressible modes become dominant within the slab component at smaller scales. These findings advance our understanding of magnetic anisotropy in solar wind turbulence and offer a new perspective on the three-dimensional turbulence cascade, with broad implications for particle transport, acceleration, and magnetic reconnection.
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All authors Siqi Zhao, Huirong Yan, Terry Z. Liu, Chuanpeng Hou

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

Extra dip in ultrahigh energy neutrino spectrum from generalized uncertainty principle

J. Barranco and Emiliano Durán

We revisited the scenario of a resonant enhancement in the oscillation probability due to an interaction potential between neutrinos and dark matter with the novelty of the inclusion of the generalized uncertainty principle. It is shown that a new resonant conversion appears at higher energies. This effect could be tested with future neutrino data as new dips in the ultrahigh energy neutrino flux.
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Earth and Planetary Astrophysics

Tidal dissipation and spin-orbit alignment due to the precessional instability in convection zones in rotating giant planets and stars

Nils B. de Vries, Adrian J. Barker and Rainer Hollerbach

Tidal dissipation in star-planet systems occurs through various mechanisms, including the precessional instability. This is an instability of laminar flows (“Poincaré flows") forced by axial precession of a rotating, oblate, spin-orbit misaligned fluid planet or star, which excites inertial waves in convective regions if the dimensionless precession rate (“Poincaré number" $\mathrm{Po}$) is sufficiently large. We constrain the contribution of the precessional instability to tidal dissipation and heat transport, using Cartesian hydrodynamical simulations in a small patch of a planet, and study its interaction with turbulent convection, modelled as rotating Rayleigh-Bénard convection. The precessional instability without convection results in laminar flow at low values and turbulent flow at sufficiently high values of $\mathrm{Po}$. The associated tidal dissipation rate scales as $\mathrm{Po}^2$ and $\mathrm{Po}^3$ in each regime, respectively. With convection, the Poincaré number at which turbulent flow is achieved shifts to lower values for stronger convective driving. Convective motions also act on large-scale tidal flows like an effective viscosity, resulting in continuous tidal dissipation (scaling as $\mathrm{Po}^2$), which obfuscates or suppresses tidal dissipation due to precessional instability. The effective viscosities obtained agree with scaling laws previously derived using (rotating) mixing-length theory. By evaluating our scaling laws using interior models of Hot Jupiters, we find that the precessional instability is significantly more efficient than the effective viscosity of convection. The former drives alignment in 1 Gyr for a Jupiter-like planet orbiting within 23 days. Linearly excited inertial waves can be even more effective for wider orbits, aligning spins for orbits within 53-142 days.
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Cosmology and Nongalactic Astrophysics

Constraining baryonic feedback and cosmology from DES Y3 and Planck PR4 6$\times$2pt data. I. $\Lambda$CDM models

Jiachuan Xu, Tim Eifler, Elisabeth Krause et al. (+3 more)

We combine weak lensing, galaxy clustering, cosmic microwave background (CMB) lensing, and their cross-correlations (so-called 6$\times$2pt) to constrain cosmology and baryonic feedback scenarios using data from the Dark Energy Survey (DES) Y3 Maglim catalog and the Planck satellite PR4 data release. We include all data points in the DES Y3 cosmic shear two-point correlation function (2PCF) down to 2.$^\prime$5 and model baryonic feedback processes via principal components (PCs) that are constructed from the ANTILLES simulations. We find a tight correlation between the amplitude of the first PC $Q_1$ and mean normalized baryon mass fraction $\bar{Y_\mathrm{b}}=\bar{f}_\mathrm{b}/(\Omega_\mathrm{b}/\Omega_\mathrm{m})$ from the ANTILLES simulations and employ an independent $\bar{Y_\mathrm{b}}$ measurement from Akino et al. (2022) as a prior of $Q_1$. We train a neural network $6\times2$pt emulator to boost the analysis speed by $\mathcal{O}(10^3)$, which enables us to run an impressive number of simulated analyses to validate our analysis against various systematics. For our 6$\times$2pt analysis, we find $S_8=0.8073\pm0.0094$ when including a $Q_1$ prior from $\bar{Y_\mathrm{b}}$ observations. This level of cosmological constraining power allows us to put tight constraints on the strength of baryonic feedback. We find $Q_1=0.025^{+0.024}_{-0.029}$ for our 6$\times$2pt analysis and $Q_1=0.043\pm{0.016}$ when combining with external information from Planck, ACT, DESI. All these results indicate weak feedback, e.g., the tensions to Illustris ($Q_1=0.095$) and OWLS AGN T8.7 ($Q_1=0.137$) are 2.9$\sigma$-3.3$\sigma$ and 4.7$\sigma$-5.9$\sigma$, respectively.
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All authors Jiachuan Xu, Tim Eifler, Elisabeth Krause, Vivian Miranda, Jaime Salcido, Ian McCarthy

High Energy Astrophysical Phenomena

BlazEr1: The eROSITA Blazar Catalog. Blazars and Blazar Candidates in the First eROSITA Survey

S. Haemmerich, A. Gokus, F. McBride et al. (+28 more)

Aims. eROSITA, on board the Spectrum Roentgen Gamma (SRG) spacecraft, performed its first X-ray all-sky survey (eRASS1) between December 2019 and June 2020. It detected about 930000 sources, providing us with an unprecedented opportunity for a detailed blazar census. We present the properties of blazars and blazar candidates in eRASS1 and the compilation of the eROSITA blazar catalog. Methods. We compiled a list of blazar and blazar candidates from the literature and matched it with the eRASS1 catalog, constructing the Blazars in eRASS1 (BlazEr1) catalog. For sources with more than 50 counts, we obtained their X-ray spectral properties. We compiled multiwavelength data from the radio to the gamma-ray regimes for all sources, including multiwavelength spectral indices and redshifts. The full catalog is available online. Results. We present the BlazEr1 catalog, containing 5865 sources, of which 2106 are associated with confirmed blazars. For 2966 sources, eROSITA provides the first X-ray data. The contamination from non-blazar sources of the entire sample is less than 11%. Most candidates exhibit properties typical for blazars. We present the properties of the entire X-ray detected blazar population, including the distributions of X-ray luminosities and photon indices, multiwavelength properties, and the blazar log N-log S distribution. Our catalog provides follow up targets, such as potential MeV and TeV blazars. Conclusions. The BlazEr1 catalog provides a compilation of X-ray detected blazars and blazar candidates. The catalog serves as a starting point for exploiting further eROSITA surveys using the same methodology, enabling us to study the X-ray variability and a large number of spectral energy distributions of blazars in the future.
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All authors S. Haemmerich, A. Gokus, F. McBride, P. Weber, L. Marcotulli, A. Zainab, W. Collmar, M. Salvato, J. Wolf, T. Sbarrato, S. Belladitta, J. Buchner, S. Saeedi, L. Dauner, M. Lorenz, O. Koenig, C. Kirsch, K. Berger, S. Bahic, D. Tubin-Arenas, M. Krumpe, D. Homan, A. Markowitz, P. Benke, F. Roesch, P. Rajasekar Kavitha, H. Tambe, M. Kadler, E. Ros, R. Ojha, J. Wilms

High Energy Astrophysical Phenomena

Population of Binary Black Holes Inferred from One Hundred and Fifty Gravitational Wave Signals

Vaibhav Tiwari

The LIGO-Virgo-KAGRA collaborations have reported gravitational wave signals from more than 150 binary black holes in the fourth catalog (GWTC-4). Here, we investigate the population properties of these binary black holes using the mixture-model framework Vamana. We present one-dimensional distributions of masses and spins, explore their correlations, and examine their evolution with redshift. These features may reflect astrophysical processes associated with binary black hole formation channels, although most remain poorly constrained. A notable feature is a peak near $10M_\odot$ in the primary mass and $8M_\odot$ in the chirp mass. Additionally, the primary and secondary masses correlate uniquely, producing pronounced peaks in the chirp mass around $14M_\odot$ and $27M_\odot$. The three peaks are roughly separated by a factor of two. A simple explanation for such well-placed peaks is a hierarchical merger scenario, in which the first peak arises from mergers of black holes of stellar origin, and higher-mass peaks arise from repeated mergers of black holes from lower-mass peaks. Although most binaries do not exhibit the high spins and characteristic mass ratios expected from hierarchical mergers, those that do are associated with the peaks observed in the chirp mass distribution.
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Astrophysics of Galaxies

Place of the Radcliffe Wave in the Local System

Vadim V. Bobylev, Nazar R. Ikhsanov and Anisa T. Bajkova

A review of publications devoted to the study of the characteristics of the Radcliffe wave has been given. The advent of mass measurements of radial velocities of stars has recently led to a number of interesting results obtained from the analysis of spatial velocities of stars and open star clusters. An important place in the study has been given to issues related to the clarification of the direct or indirect influence of magnetic fields on the process of formation of the Radcliffe wave. The hypothesis of Parker instability of the galactic magnetic field as one of the reasons for the formation of wave-type inhomogeneities in the galactic disk has been discussed.
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Earth and Planetary Astrophysics

Engulfment of Eccentric Planets by Giant Stars: Hydrodynamics and Light Curves

Mengqi Yang, Dong Lai, Fuyuan Wu et al. (+1 more)

Recent observations suggest that planetary engulfment by a giant star may produce radiation that resembles subluminous red novae. We present three-dimensional hydrodynamical simulations of the interaction between an eccentric $5 \,M_J$ giant planet and its $1\,M_\odot$ red-giant host star. The planet's pericenter is initially $60\%$ of the stellar radius and is fully engulfed after tens of orbits. Once inside the stellar envelope, the planet generates pressure disturbances that steepen into shocks, ejecting material from the envelope. We use post-processing to calculate the light curves produced by planetary engulfment. We find that the hot stellar ejecta enhances the stellar luminosity by several orders of magnitude. A prolonged hydrogen recombination plateau appears when the ejecta cools to about $10^4\,\rm{K}$. The late-time rapid dimming of the light curve follows dust formation, which obscures the radiation. For planets with lower eccentricity, the orbital decay proceeds more slowly, although the observable properties remain similar.
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All authors Mengqi Yang, Dong Lai, Fuyuan Wu, Jie Zhang

Astrophysics of Galaxies

Filamentary accretion flows in high-mass star-forming clouds

J.-E. Schneider, H. Beuther, C. Gieser et al. (+11 more)

We quantify the gas flows from a scale of up to several parsecs down to the sub-parsec scale along filamentary structures in the three high-mass star-forming regions G75.78, IRAS21078+5211 and NGC7538 with data obtained from the IRAM 30 m telescope. The analysis is carried out using the surface density derived from 1.2 mm continuum emission and velocity differences estimated from HCO$^+$ and H$^{13}$CO$^+$ molecular line data.
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All authors J.-E. Schneider, H. Beuther, C. Gieser, S. Jiao, M.R.A. Wells, R. Klessen, S. Feng, P. Klaassen, M. T. Beltran, R. Cesaroni, S. Leurini, J.S. Urquhart, A. Palau, R. Pudritz

High Energy Astrophysical Phenomena · Cross-listed from physics.plasm-ph

Global Non-Axisymmetric Hall Instabilities in a Rotating Plasma

Alexandre Sainterme and Fatima Ebrahimi

Non-axisymmetric, flow-driven instabilities in the incompressible Hall-MHD model are studied in a differentially rotating cylindrical plasma. It is found that in the Hall-MHD regime, both whistler waves and ion-cyclotron waves can extract energy from the flow shear, resulting in two distinct branches of global instability. The non-axisymmetric whistler modes grow significantly faster than non-axisymmetric, ideal MHD modes. A discussion of the global whistler instability mechanism is presented in the large-ion-skin-depth, `electron-MHD' limit. When the magnetic field is azimuthal, a subset of the whistler modes having zero axial wave number are uncovered to be destabilized by the `co-rotation amplifier' mechanism. It is observed that the effect of the Hall term on the non-axisymmetric modes can be appreciable when $d_i$ is on the order of a few % of the width of the cylindrical annulus. Distinct global modes emerge in the strong Hall-MHD regime at significantly stronger magnetic fields than those required for unstable global MHD modes, as the Hall effect weakens the stabilizing `field-line bending' by decoupling ion motion from the magnetic field. These global non-axisymmetric modes may play an important role in weakly ionized accretion disks.
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High Energy Astrophysical Phenomena

Analytical approaches for rapid prediction of gravitational waveforms for relativistic binary systems

Aleksandra V. Mishakina and Sergei I. Blinnikov

We present a fast method for obtaining fully analytical approximations for gravitational waveforms produced by merging of neutron stars and/or black holes for the earliest stages of the merger process. The obtained analytical formula is compared with numerical calculations, its accuracy and limits of applicability are evaluated. Our results may be useful not only for the earliest evalution of properties of the nature of binary system in gravitational-wave detectors but also will give early alerts for gamma-ray, optical and neutrino observatories.
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Solar and Stellar Astrophysics

Solar photospheric velocities measured in space: a comparison between SO/PHI-HRT and SDO/HMI

D. Calchetti, K. Albert, F.J. Bailén et al. (+15 more)

The Polarimetric and Helioseismic Imager (SO/PHI) onboard Solar Orbiter is a spectropolarimeter scanning the Fe I line at 617.3 nm, providing data of the solar photosphere. The same line is sampled by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) and many other on-ground instruments. In this paper, we aim at assessing the consistency between line-of-sight (LoS) velocity measurements from the two instruments. Reliable measurements of up and down flows from SO/PHI are crucial and unique when Solar Orbiter is facing the far side of the Sun. Also, a combination of measurements from two vantage points to study horizontal flows must rely on consistent observations. For this purpose, we compare the LoS velocity measured by SO/PHI's High Resolution Telescope (SO/PHI-HRT) and SDO/HMI on 29 March 2023, when Solar Orbiter was crossing the Sun-Earth line at a distance of 0.39 au from the Sun. Because such co-alignments are rare, this configuration offered an almost unique opportunity to directly compare data products from both telescopes. The data are aligned and remapped to allow a pixel-by-pixel comparison of the whole time series of 4 hours length. Temporal and spatial variations are considered for a direct combination of the measurements. The LoS velocity distributions are evaluated and a clear linear relation is found between the two instruments with a slope of 0.96 and a correlation of 92%. We find that the signals form at similar heights, with a separation of 7$\pm$14 km, which is larger than previous estimates. A close-up look at the penumbra of a sunspot and its Evershed flow is presented. We conclude that the signals inferred by SO/PHI-HRT and SDO/HMI show very good agreement and high correlation when instrumental effects and large-scale velocities on the Sun are properly accounted for.
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All authors D. Calchetti, K. Albert, F.J. Bailén, J. Blanco Rodríguez, J.S. Castellanos Durán, A. Feller, A. Gandorfer, J. Hirzberger, J. Sinjan, X. Li, T. Oba, D. Orozco Súarez, T.L. Riethmüller, J. Schou, S.K. Solanki, H. Strecker, A. Ulyanov, G. Valori

Solar and Stellar Astrophysics

The R-Process Alliance: Exploring the cosmic scatter among ten r-process sites with stellar abundances

Mila Racca, Terese T. Hansen, Ian U. Roederer et al. (+11 more)

The astrophysical origin of the rapid neutron-capture process (r-process), which produces about half of the elements heavier than iron, remains uncertain. The oldest, most metal-poor stars preserve the chemical signatures of early nucleosynthesis events and can reveal the nature of the r-process sites. We present a homogeneous chemical abundance analysis of ten r-process-enhanced, metal-poor stars that show strong enrichment in r-process elements with minimal contamination from other nucleosynthetic sources. Using high-resolution, high signal-to-noise spectra, we examined over 1400 absorption lines per star through equivalent width measurements and spectral synthesis under one-dimensional LTE assumptions with the MOOG radiative transfer code. Abundances for 54 chemical species were derived, including 29 neutron-capture elements spanning the full r-process pattern. We quantified the cosmic scatter of elemental ratios relative to Zr (light) and Eu (heavy) and found remarkably small dispersions for the rare-earth and third-peak elements, {\sigma}[La/Eu] = 0.08 dex and {\sigma}[Os/Eu] = 0.11 dex, while the light-to-heavy ratio shows slightly larger variation, {\sigma}[Zr/Eu] = 0.18 dex. A kinematic study indicates that the stars likely originated from ten distinct progenitor systems, allowing us to probe the intrinsic variation between independent r-process events. These results imply that the main r-process operates under highly uniform conditions across diverse astrophysical sites.
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All authors Mila Racca, Terese T. Hansen, Ian U. Roederer, Vinicius M. Placco, Anna Frebel, Timothy C. Beers, Rana Ezzeddine, Erika M.Holmbeck, Charli M. Sakari, Stephanie Monty, Øivind Harket, Joshua D. Simon, Chris Sneden, Ian B. Thompson

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

Matter Sourced Bubble Nucleation in the Asymmetron Scalar-Tensor Theory

Usama Syed Aqeel, Clare Burrage, Oliver Gould et al. (+1 more)

We investigate how matter density distributions affect thin-wall bubble formation in the asymmetron mechanism, a scalar-tensor theory with a universal coupling to matter and explicit symmetry-breaking, and analyse the stability of its metastable state. We show that the screening mechanism of the asymmetron inside dense objects induces a surface tension associated with the boundary of the screening object, leading to a richer class of bubble solutions than the standard Coleman-Callan bulk nucleation. These boundary surface tensions are used to modify the Nambu-Goto action for instantons, allowing for the computation of the corresponding Euclidean action for bubbles nucleating on flat planes, as well as on concave and convex cylindrical surfaces. We find that the smallest Euclidean action occurs for bubbles nucleating along the edge of a concave spherical surface. Comparing this edge nucleation channel with the bulk one, we determine the maximum curvature radius for which concave edge nucleation is preferred. Since the maximum radius of curvature is exponentially suppressed by the action of a bulk bubble, we find that within the regime of the instanton approximation, edge nucleation is always preferred. This is largely due to the weak couplings of the asymmetron. We apply these findings to determine the maximum curvature radius of a cosmic void and discuss how our results affect the seeding of $N$-body simulations of asymmetron domains, showing that domain wall nucleation preferentially occurs at the edges of cosmological voids. We also demonstrate that the presence of a homogeneous gas around the dense substrates reduces the maximum curvature radius, enabling bulk bubbles to form preferentially as the asymmetron undergoes a density-driven phase transition.
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All authors Usama Syed Aqeel, Clare Burrage, Oliver Gould, Paul M. Saffin

Cosmology and Nongalactic Astrophysics

Constraints on Cosmic Birefringence from SPIDER, Planck, and ACT observations

Lu Yin, Shuhang Xiong, Joby Kochappan et al. (+2 more)

The Early Dark Energy (EDE) model has been proposed as a candidate mechanism to generate cosmic birefringence through a Chern-Simons coupling between a dynamical scalar field and the cosmic microwave background (CMB) photon. Such birefringence induces a nonzero cross-correlation between the CMB $E$- and $B$-modes, providing a direct observational signature of parity violation. Recent measurements of the $EB$ and $TB$ power spectra, however, cannot yet unambiguously separate instrumental miscalibration ($\alpha$) from a true cosmic-rotation angle ($\beta$). For this reason, we perform a model-independent analysis in terms of the total effective rotation angle $\alpha+\beta$. We analyze the latest $EB$ and $TB$ measurements from the SPIDER, Planck, and ACT experiments and derive constraints on the Chern-Simons coupling constant $gM_{Pl}$ and on the polarization rotation angle $\alpha+\beta$. We find that the coupling $gM_{Pl}$ is not compatible with the SPIDER data, while it provides reasonable fits to the Planck and ACT measurements. The fits for $\alpha+\beta$ prefer a value larger than zero: when combined, Planck+ACT yield a detection significance of approximately 7$\sigma$. We also find that ACT data alone do not provide sufficiently tight constraints on either $gM_{Pl}$ or $\alpha+\beta$, whereas the combination Planck+ACT improves the statistical consistency of ACT's high-$\ell$ results and leads to a better PTE for those measurements.
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All authors Lu Yin, Shuhang Xiong, Joby Kochappan, Bum-Hoon Lee, Tuhin Ghosh

Astrophysics of Galaxies

A constant pressure model for the warm absorber in Mrk 509

Krzysztof Hryniewicz, Agata Różańska, Tek Prasad Adhikari et al. (+3 more)

We present the analysis of 900 ks high-resolution RGS XMM-Newton observations of the nearby Seyfert galaxy Mrk 509 with the use of a self-consistent warm absorber (WA) model. We perform a physically motivated approach to the modeling of WA as a stratified medium in constant total pressure (CTP) regime. Powerful outflows are fundamental ingredients of any active galactic nuclei (AGN) structure. They may significantly affect the cosmological environment of their host galaxy. High-resolution X-ray data are best suited for outflow's studies, and the observed absorption lines on heavy elements are evidence of the physical properties of an absorbing gas. Our models allow us to fit continuum shapes bounded together with the line profiles, which gives additional constraints on the gas structure of WA in this source. In this work, we benchmark and test the CTP model on the soft X-ray spectrum of Mrk 509. A grid of synthetic absorbed spectra was computed with the photoionization code Titan assuming that the system was under CTP. As an illuminating spectral energy distribution (SED), we used the most actual multiwavelength observations available for Mrk 509. We apply these models to the high-resolution spectrum of the WA in the Mrk 509, taking into account cold/warm/hot Galactic absorption on the way to the observer. CTP gas with $\log \xi_{0} \sim 1.9$, defined on the cloud surface, fits the data well. A higher ionization component is needed for Ne X absorption. The best-fit model is optically thin with $\log N_{\rm H }= 20.456 \pm 0.016$. The lines are non-saturated, and the CTP spectral fit aligns with previous analyses of Mrk 509 with a constant density WA. The model constrains the gas density, placing the WA cloud at 0.02 pc, consistent with the inner broad line region and the thickening region of the accretion disk.
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All authors Krzysztof Hryniewicz, Agata Różańska, Tek Prasad Adhikari, Matteo Guainazzi, Biswaraj Palit, Rafał Wojaczyński

Solar and Stellar Astrophysics

Coronal electron density: Insights from radio and in situ observations, and EUHFORIA modeling

Ketaki Deshpande, Jasmina Magdalenic, Immanuel Christopher Jebaraj et al. (+4 more)

The distribution of the coronal electron density at different distances from the Sun strongly influences the physical processes in the solar corona and is therefore a very important topic in solar physics. Most methods, including radio observations, used for estimating coronal electron density were not fully validated due to the absence of in situ observations closer to the Sun. Consequently, space weather forecasting models that simulate coronal density lacked proper validation. Newly available PSP in situ observations at distances close to the Sun provide an opportunity to study plasma properties near the Sun and to compare observational and modeling results. This work studies type III bursts, estimates their propagation path, and validates coronal electron density obtained from radio, in situ observations, and modeling with EUHFORIA. Type III bursts observed during the second PSP perihelion are analyzed using radio triangulation and modeling. We determine 3D positions of radio sources and use EUHFORIA to estimate electron densities at various locations. The electron densities derived from radio observations and EUHFORIA modeling are inter-validated with in situ PSP measurements. We studied 11 type III bursts during the second PSP perihelion, with radio triangulation showing propagation paths southward from the solar ecliptic plane. Radio source sizes ranged from 0.5 to 40 deg (0.5 to 25 Rs) with no clear frequency dependence, indicating that scattering of radio waves was not very significant. Comparison of electron densities from radio triangulation, PSP data, and EUHFORIA modeling showed a large range of values, influenced by different propagation paths and model limitations. Despite these variations, EUHFORIA identified high-density regions along type III burst paths.
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All authors Ketaki Deshpande, Jasmina Magdalenic, Immanuel Christopher Jebaraj, Senthamizh Pavai Valliappan, Antonio Niemela, Luciano Rodriguez, Vratislav Krupar