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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 5 February

High Energy Astrophysical Phenomena

Searching for dark matter signals with high energy astrophysical neutrinos in IceCube

Khushboo Dixit, Gopolang Mohlabeng and Soebur Razzaque

High-energy neutrinos provide a potentially powerful and distinctive probe for dark matter (DM) - neutrino interactions, particularly in environments with enhanced DM densities, such as the DM spikes predicted to form around supermassive black holes (SMBHs) at the center of active galactic nuclei (AGN). Recent results by the IceCube Neutrino Observatory, which reported four significant AGNs, namely TXS 0506+056, NGC 1068, PKS 1424+240, and NGC 4151 as candidate neutrino sources, provide a valuable opportunity to search for signatures of these interactions. In this study, we use IceCube data to derive the most stringent constraints to date on both the energy-dependent and energy-independent DM-neutrino scattering cross-sections. We perform a statistical analysis using data from individual sources as well as a combined (stacked) analysis of all four sources. Our strongest limits arise from the stacking analysis, yielding an upper bound of $\sigma_{0} \lesssim 8\times 10^{-39}$ cm$^2$ for an energy-independent cross-section and $\sigma_{0} \lesssim 10^{-39}$ cm$^2$ for a linearly energy-dependent cross-section, both at 90$\%$ confidence level, particularly in scenarios involving the adiabatic growth of black holes.
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Astrophysics of Galaxies

Modelling the photometric and morphological evolution of disc galaxies in the cluster environment

A. Marasco, B.M. Poggianti, B. Vulcani et al. (+3 more)

Observations indicate that the disc population in galaxy clusters has undergone rapid evolution, transitioning from a dominance of blue spirals to red S0s over the past $\sim7$ Gyr. We build a simplified cluster evolutionary model in the $\Lambda$CDM framework to constrain the characteristic timescales of this transformation. In our model, field spirals joining the cluster are subject to ram-pressure stripping (RPS), which removes their gas reservoir leading to the quenching of their star formation on a timescale $t_{\rm s}$, and to an (initially) unspecified mechanism that transforms them into S0s on a timescale $t_{\rm m}$. We assume that $t_{\rm s}$ and $t_{\rm m}$ are independent and both power-law functions of $M_\star/M_{\rm cl}$, the galaxy-to-cluster mass ratio. We constrain our model using the observed distribution of spirals and S0s in a color-mass plane from the OmegaWINGS and EDisCS cluster surveys at $z\simeq0.055$ and $z\simeq0.7$. Our best-fit model reproduces the data remarkably well and predicts evolutionary trends for the main morphological fractions in agreement with previous studies. We find typical $t_{\rm s}$ between $0.1$ and $1$ Gyr, compatible with previous estimates. A surprisingly strong anti-correlation between $t_{\rm s}$ and $M_\star/M_{\rm cl}$ is required in order to suppress the formation of red, low-mass spirals at low redshift, which we interpret as driven by orbit anisotropy. Conversely, $t_{\rm m}$ depends very weakly on $M_\star/M_{\rm cl}$ and has typical values of a few Gyr. The inferred morphological evolution is compatible with that resulting from the ageing of the stellar populations in galaxies abruptly quenched by ram pressure stripping: we confirm spectrophotometric ageing as a key channel for the spiral-to-S0 transition in galaxy clusters, with secular evolution playing a secondary role.
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All authors A. Marasco, B.M. Poggianti, B. Vulcani, A. Moretti, M. Gullieuszik, J. Fritz

Astrophysics of Galaxies

The Host Galaxies of Active Galactic Nuclei with Direct Black Hole Mass Measurements

Vardha N. Bennert, Nico Winkel, Tommaso Treu et al. (+13 more)

Reverberation mapping (RM) determines the mass of black holes (BH) in active galactic nuclei (AGNs) by resolving the BH gravitational sphere of influence in the time domain. Recent RM campaigns yielded direct BH masses through dynamical modeling for a sample of 32 objects, spanning a wide range of AGN luminosities and BH masses. In addition, accurate BH masses have been determined by spatially resolving the broad-line region with GRAVITY for a handful of AGNs. Here, we present a detailed analysis of Hubble Space Telescope images using surface-brightness profile fitting with state-of-the-art programs. We derive AGN luminosity and host-galaxy properties, such as radii and luminosities for spheroid, disk, and bar (if present). The spheroid effective radii were used to measure stellar velocity dispersion from integral-field spectroscopy. Since the BH masses of our sample do not depend on any assumption of the virial factor needed in single-epoch spectroscopic mass estimates, we can show that the resulting scaling relations between the mass of the supermassive BHs and their host galaxies match those of quiescent galaxies, naturally extending to lower masses in these (predominantly) spiral galaxies. We find that the inner AGN orientation, as traced by the broad-line region inclination angle, is uncorrelated with the host-galaxy disk. Our sample has the most direct and accurate MBH measurements of any AGN sample and provides a fundamental local benchmark for studies of the evolution of massive black holes and their host galaxies across cosmic time.
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All authors Vardha N. Bennert, Nico Winkel, Tommaso Treu, Xuheng Ding, Vivian U, Raymond P. Remigio, Aaron J. Barth, Matthew A. Malkan, Lizvette Villafaña, Samantha Allen, Ellie Johnson, Sebastian Contreras, Minjin Kim, Simon Birrer, Knud Jahnke, Shaoping Zheng

Cosmology and Nongalactic Astrophysics

Consistency of standard cosmologies using Bayesian model comparison and tension quantification

Lukas Tobias Hergt, Sophie Henrot-Versillé, Matthieu Tristram et al. (+1 more)

We present a unified Bayesian assessment of model comparison and data-set consistency for LCDM (cold dark matter plus a cosmological constant) and minimal extensions (neutrino mass, spatial curvature, constant or evolving dark energy) using cosmic microwave background (CMB), baryon acoustic oscillation (BAO), and type Ia supernova (SN) data. The major results are summarized in the first three figures. We quantify model preference with Bayesian evidence and assess consistency with complementary evidence- and likelihood-based diagnostics applied uniformly across data-set combinations. For the models considered, updated Planck processing systematically improves internal CMB consistency (low-$\ell$ versus high-$\ell$, and primary CMB versus CMB lensing). The preference for a closed geometry and an associated “curvature tension” with BAO and/or CMB lensing are largely confined to earlier Planck likelihood implementations and weaken substantially when using updated CMB processing and more recent BAO measurements. Apparent evidence for evolving dark energy in CMB+BAO+SN combinations depends sensitively on the specific pairing of CMB and SN likelihoods: plausible alternatives shift inferred tensions by more than $1\,\sigma$ and can completely reverse the preferred model. Allowing a free neutrino mass tends to absorb residual shifts without introducing new inconsistencies, and we do not find robust evidence for a standalone $\tau$-driven discrepancy once the full likelihood context is accounted for. We conclude that claims of a required update of our standard cosmological model from LCDM to $w_0w_a$CDM are premature.
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All authors Lukas Tobias Hergt, Sophie Henrot-Versillé, Matthieu Tristram, Douglas Scott

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

Scalar Tsunamis from Black Hole Formation

Arturo de Giorgi, Yeray Garcia del Castillo and Joerg Jaeckel

Stars and other macroscopic objects may be surrounded by potentially large field configurations of very light scalars coupled to ordinary matter. If the star ends in a black hole, e.g. via a supernova or a neutron star merger, the source vanishes, and the field is released. In this paper, we improve on previous estimates for the field configurations arriving at large distances by including the effects of general relativity and an improved modelling of the initial field configurations. The total amount of energy released is typically of the same order of magnitude as suggested by simple flat space estimates. The spectrum receives noticeable corrections.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Dark Matter Heating of Compact Stars Beyond Capture: A Relativistic Framework for Energy Deposition by Particle Beams

Jaime Hoefken Zink, Shihwen Hor and Maura E. Ramirez-Quezada

Compact astrophysical objects, such as neutron stars and white dwarfs, can act as detectors of energetic particle fluxes originating from astrophysical accelerators. While most existing capture and heating calculations assume isotropic very low energetic incident fluxes from the halo dark matter, many realistic sources produce highly directional beams or jets, for which gravitational focusing, trajectory multiplicity, and local energy deposition must be treated consistently. In this work, we develop a general relativistic formalism to compute the local density, capture probability, and energy deposition of particles arriving as directed beams onto compact objects. The framework is based on the mapping of an asymptotic particle flux to local densities through geodesic congruences, allowing for gravitational focusing, multi-stream regions, and optical depth effects to be incorporated in a unified way. The formalism applies to arbitrary particle species and interaction models, and separates capture from through-going energy deposition in a frame-consistent manner. As an explicit application, we consider relativistic particle beams generated in astrophysical jets and evaluate their interaction with two compact objects samples: a white dwarf and a neutron star. In particular, we illustrate the framework using boosted dark matter produced in a list of 324 blazars as a representative case study, computing the resulting fluxes and the associated heating in the selected stars. Additional regimes such as the interaction roof and geometric limit are discussed, highlighting the conditions under which compact objects can efficiently convert incident beam energy into observable heating.
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Instrumentation and Methods for Astrophysics

Correlation Calibration: A Hybrid Calibration Technique for Radio Interferometric Arrays

Robert Pascua, Jonathan Sievers and Adrian Liu

Calibrating out per-antenna signal chain effects is an essential step in analyzing radio interferometric data. For drift-scanning arrays, robustly calibrating the data is especially challenging due to the lack of the ability to track a calibration source. Consequently, calibration strategies for drift-scanning arrays are limited by our knowledge of the radio sky at large, as well as the direction-dependent instrument response. In the context of 21 cm cosmology, where small calibration errors can conspire to overwhelm the cosmological signal, it is therefore crucially important to develop calibration strategies that are capable of accurately calibrating the data in the presence of sky or instrument modeling errors. In this paper we present CorrCal, a covariance-based calibration strategy for redundant radio interferometric arrays. CorrCal is a hybrid calibration strategy that leverages the strengths of traditional sky-based calibration and redundant calibration in a computationally efficient framework that is fairly insensitive to modeling errors. We find that the calibration errors from CorrCal are unbiased and far below typical thermal noise thresholds across a wide range of modeling error scenarios. We show that CorrCal is computationally efficient: our implementation is capable of evaluating the likelihood and its gradient in less than a second for 1,000-element class arrays using just a single laptop core. Given CorrCal's computational efficiency and robustness to modeling errors, we anticipate that it will serve as a useful tool in the analysis of radio interferometric data from current and next-generation experiments targeting the cosmological 21 cm signal.
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Cosmology and Nongalactic Astrophysics

Exploring Cosmological Tensions with Hubble Parameter Tomography via Linear Cosmography

Brett Bochner and Aiden Jin

Given the persistence of various tensions in the "Cosmic Concordance" – such as the "Hubble Tension", and possible departures from LambdaCDM time evolution – seen from combinations of complementary data sets (e.g., Cosmic Microwave Background, Baryon Acoustic Oscillations, Type Ia Supernovae), it remains an ongoing possibility for these to have a real cosmological origin. If one assumes such deviations to be real, a model-independent formalism (cosmography) is useful for locating the source of the problem with concordance cosmology. The extraordinarily good fit of LambdaCDM to CMB data shows that it was a successful model of the universe at high redshift. Yet at lower redshift – when the dark energy density becomes significant, and its precise physical nature becomes important – the universe may have gone off the track of simple LambdaCDM. Here we use linear cosmography fits to binned Supernova data to reconstruct the detailed temporal history of the Hubble parameter, probing for interesting time-dependent behaviors of the expansion rate during and after the onset of cosmic acceleration. Using combined Type Ia supernovae from the Dark Energy Survey 5-Year data release and the Union2.1 compilation, we find intriguing hints of oscillations in the Hubble parameter during the acceleration era. While these hints are of limited statistical significance, and not robust under different redshift binnings, we present this work as a proof-of-concept demonstration of this method for reconstructing the Hubble parameter evolution, which may be useful for the voluminous Supernova data sets anticipated to become available during the next few years.
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Cosmology and Nongalactic Astrophysics

ACT DR6+Planck impact on inflation with non-zero vacuum expectation value and the post-inflationary behavior

F. B. M. dos Santos, J. G. Rodrigues, G. Rodrigues et al. (+2 more)

The impact of the most recent cosmic microwave background (CMB) data from the Atacama Cosmology Telescope (ACT) is studied for a model of cosmic inflation which predicts a non-zero vacuum expectation value (VEV) $M$ for a large-field regime. Since lower values of $M$ are compatible with the higher spectral index $n_s$ provided by the ACT+Planck joint analysis, we establish new limits on this parameter while also considering further CMB data from the latest BICEP/Keck Array release for CMB polarization modes. We find $\log_{10}M/M_{Pl}=-2.5^{+1.1}_{-1.3}$ at 68% confidence level, compatible with $M/M_{Pl}\simeq 0.003$, which is interesting for post-inflationary processes, such as preheating. We conduct a lattice simulation for the inflaton field for the first few e-folds, as the model is compatible with the production of relics such as oscillons, which are possible candidates as sources of gravitational waves and primordial black holes. We find that the model indeed produces localized, quasi-spherical structures compatible with oscillons, which might lead to signatures detectable by future experiments. However, in agreement with recent works, we find that although the abundance of gravitational waves that could be generated in this regime has an amplitude well within the sensitivities of these detectors, the frequency range is on the GHz limit, away from the expected frequencies. Finally, we estimate the impact of a coupling of the type $y\phi\chi^2$ to the inflaton, in the realization of perturbative reheating, directly impacting the predictions of the model, as lower values of $M$ are consistent with both the entire allowed temperature range, and the limits imposed by BICEP/Keck Array+Planck+ACT.
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All authors F. B. M. dos Santos, J. G. Rodrigues, G. Rodrigues, C. Siqueira, J. S. Alcaniz

Astrophysics of Galaxies

Water absorption confirms cool atmospheres in two little red dots

Bingjie Wang, Joel Leja, Ivo Labbe et al. (+35 more)

Little red dots (LRDs) are an abundant population of compact high-redshift sources with red rest-frame optical continua, discovered by the James Webb Space Telescope (JWST). Their red colors and power sources have been attributed either to dust reddening of standard hot accretion disks or to intrinsically cool thermal emission from dense hydrogen envelopes, in both cases surrounding accreting supermassive black holes. These scenarios predict order-of-magnitude differences in emission temperature but have lacked decisive temperature diagnostics. Here we report a prominent absorption feature at rest-frame $\sim 1.4 \, \mu\mathrm{m}$ in two out of four LRDs at $z \sim 2$ with high signal-to-noise JWST spectra, among the coolest from a large LRD sample. The feature matches the shape and wavelength of the water absorption band seen in cool stars. Atmosphere models require $T \lesssim 3000\, \mathrm{K}$ to reproduce it, confirming unambiguously the presence of a cool, dense gas component contributing $20-30\%$ to the emergent continuum. A composite model reproduces both the absorption and the rest-frame optical-to-infrared continuum shape and suggests a temperature range ($\sim2000\, \mathrm{K} - 4000 \, \mathrm{K}$) rather than a single blackbody predicted by some gas envelope models. Molecular absorption demonstrates that the red continua of some LRDs are intrinsic rather than dust-reddened, implying order-of-magnitude lower bolometric luminosities and black-hole masses, and providing a new diagnostic of the emitting gas.
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All authors Bingjie Wang, Joel Leja, Ivo Labbe, Jenny E. Greene, Hanpu Liu, Anna de Graaff, Raphael E. Hviding, Jorryt Matthee, Eliot Quataert, Rachel Bezanson, Leindert A. Boogaard, Gabriel Brammer, Adam J. Burgasser, Yi-Xian Chen, Nikko J. Cleri, Sam E. Cutler, Pratika Dayal, Lukas J. Furtak, Seiji Fujimoto, Karl Glazebrook, Andy D. Goulding, Jakob M. Helton, Michaela Hirschmann, Yan-Fei Jiang, Vasily Kokorev, Yilun Ma, Tim B. Miller, Rohan P. Naidu, Pascal Oesch, Richard Pan, Casey Papovich, Sedona H. Price, Hans-Walter Rix, David J. Setton, Wendy Q. Sun, John R. Weaver, Katherine E. Whitaker, Adi Zitrin

Cosmology and Nongalactic Astrophysics

Testing cosmic anisotropy with cluster scaling relations

Tariq Yasin, Richard Stiskalek, Harry Desmond et al. (+2 more)

We test claims of large-scale anisotropy in the local expansion rate using cluster scaling relations as distance indicators. Using a Bayesian forward model, we jointly fit the X-ray luminosity–temperature (LT) and thermal Sunyaev-Zel'dovich–temperature (YT) relations, marginalising over the latent cluster distances and modelling selection effects as well as peculiar velocities. The latter are modelled using reconstructions of the local peculiar velocity field where we self-consistently account for possible anisotropic redshift–distance relations via an approximate scheme. This treatment proves crucial to the inferred anisotropy and breaks the degeneracy between anisotropy in scaling relation normalisations and underlying cosmological anisotropy. We apply our method to 312 clusters at $z \lesssim 0.2$, testing dipolar, quadrupolar and general (pixelised) anisotropy models. Bayesian model selection finds no more than weak evidence for any anisotropic model. For dipole models, we obtain upper limits of $\delta H_0 / H_0 < 3.2\%$ and bulk flow magnitude $< 1300\,\mathrm{km\,s^{-1}}$. Our results contrast with previous claims of statistically significant anisotropy from the same data, which we attribute to our principled forward modelling of both redshifts and scaling relation observables through latent distances and our treatment of the impact of anisotropic redshift–distance relations when modelling the local peculiar velocity field. Our work highlights the importance of accurately modelling peculiar velocities when testing isotropy with distance indicators, and motivates the further development of reconstructions that self-consistently treat large-scale deviations from the Hubble flow.
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All authors Tariq Yasin, Richard Stiskalek, Harry Desmond, Sebastian von Hausegger, Pedro G. Ferreira

Instrumentation and Methods for Astrophysics

Direction-dependent calibration with image-domain gridding

Sebastiaan van der Tol, Sarod Yatawatta, Bram Veenboer et al. (+1 more)

Wide-field images made by radio interferometers are invariably affected by direction-dependent systematic effects such as the ionosphere or the beam pattern. Calibration along a set of discrete directions in the sky is the default technique to estimate and correct these systematic errors. However, additional processing such as smoothing and mosaicing are required to reconcile the step wise variation of the estimated systematic errors at the edges of the discrete directions (facets). We overcome the discrete nature of direction-dependent calibration by using image-domain gridding as the model for the calibration. Instead of discrete directions in the sky, calibration is performed using a basis that represents a set of sub-grids in the Fourier space. This automatically removes the need for extra operations to recover the wide-field systematics error model without any discontinuity. We provide results based on LOFAR data where we compare the traditional facet-based (discrete directional gains) calibration with the proposed approach. The comparison shows improved image quality, mainly because of the physical plausibility of the proposed approach as opposed to using a piecewise constant model for direction-dependent systematic errors.
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All authors Sebastiaan van der Tol, Sarod Yatawatta, Bram Veenboer, David Rafferty

High Energy Astrophysical Phenomena

Time lags and their association with the Boundary Layer structure in a Z source GX 349+2

Abhishek M.V.R., Sriram K and Gouse SD

Studying the cross-correlation function between the soft and hard X-ray emission in Neutron Star Low Mass X-ray Binaries provides crucial insight into the structure and dynamics of the innermost accretion regions. In this work, we investigate the CCF of the Z-source GX 349+2 using an XMM-Newton observation. We noted that asymmetric CCFs with lags of a few hundred secondsbetween soft and hard band LCs in the horizontal branch, whereas CCFs remained symmetric in normal and flaring branches. We also performed a CCF study during the flux transition duration and observed lags of the order of a few tens to hundreds of seconds. Monte Carlo simulations were performed to assess the robustness of these CCFs, confirming their significance at a 95% confidence level. Spectral analysis during the flux transitions further suggests that the inner accretion disk extends close to the last stable orbit. We propose that the observed hard lags arise from the readjustment of the boundary layer/coronal region located near the inner edge of the accretion disk. From the measured lags, we estimate the characteristic size of the boundary layer. We show that the observed lags could also be associated with the depletion timescale of the boundary layer with low viscosity.
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Cosmology and Nongalactic Astrophysics

Does Cosmology require Hermiticity in Quantum Mechanics?

Oem Trivedi and Alfredo Gurrola

We explore the consequences of allowing non-Hermitian structures in quantum cosmology by extending the Wheeler DeWitt framework beyond strictly Hermitian dynamics. Using a controlled semiclassical reduction, we show how anti Hermitian contributions propagate into both early universe primordial fluctuations and late-time structure growth as effective damping or gain terms. Confronting this framework with inflationary observables, growth of structure and the observed near flatness of the universe, we derive strong infrared constraints that suppress non Hermiticity across cosmic history. We demonstrate that these bounds are mutually consistent between early and late-time probes and can be partially relaxed in theories beyond General Relativity. Our results establish cosmology as a novel arena for testing foundational aspects of quantum mechanics and suggest that Hermiticity may emerge dynamically along the semiclassical branch describing our universe.
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Cosmology and Nongalactic Astrophysics

Cosmography with gravitational waves I: Taylor expansion in the low-redshift regime

Jonathan Morais, Rodrigo Gonçalves and Jailson Alcaniz

We evaluate the capability of current and next-generation gravitational-wave detectors, including Advanced LIGO, the Einstein Telescope, and DECIGO, to probe cosmographic parameters using electromagnetically bright standard sirens. Adopting a third-order Taylor expansion, we examine the constraints primarily as a function of the number of detections and, in a complementary analysis, across correlated SNR–redshift regimes. Advanced LIGO can provide a distance-ladder-independent measurement of $H_0$ at the percent level. As the catalogue size increases, the Einstein Telescope reaches subpercent precision on $H_0$ and measures $q_0$ at the tens-of-percent level. DECIGO extends this sensitivity to $j_0$, achieving precision at the few-tens-of-percent level.
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High Energy Astrophysical Phenomena

Improved Heavy Dark Matter Annihilation Search from Dwarf Galaxies with HAWC

A. Albert, R. Alfaro, C. Alvarez et al. (+103 more)

Understanding dark matter's elusive nature is crucial for the framework of particle physics and expanding the Standard Model. This analysis utilizes the High Altitude Water Cherenkov (HAWC) gamma ray Observatory to indirectly search for dark matter (DM) by studying gamma ray emission from dwarf spheroidal galaxies (dSphs). Selected for their high ratio of dark matter to baryonic matter, dSphs are useful for this type of search owing to the low background emission. In comparison to previous HAWC studies, we significantly improve our sensitivity to DM from dSphs due to improvements to our event reconstruction and reduced hadronic contamination. We expanded the number of dSphs studied, DM annihilation channels into the Standard Model (SM), and the amount of data collected on each previously studied dSph. We searched for DM signals in each dSph using the latest version of the algorithms used to reconstruct data from the primary detector of the HAWC instrument. We report that we do not detect evidence of DM from dSphs, so we place upper limits for the velocity-weighted DM annihilation cross-section ($\langle\sigma v \rangle$) on the order of $10^{-23}~\text{cm}^3\text{s}^{-1}$ for a DM mass range of $1-10^4$ TeV.
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All authors A. Albert, R. Alfaro, C. Alvarez, A. Andrés, E. Anita-Rangel, M. Araya, J.C. Arteaga-Velázquez, D. Avila Rojas, H.A. Ayala Solares, R. Babu, P. Bangale, E. Belmont-Moreno, A. Bernal, K.S. Caballero-Mora, T. Capistrán, A. Carramiñana, F. Carreón, S. Casanova, A.L. Colmenero-Cesar, U. Cotti, J. Cotzomi, S. Coutiño de León, E. De la Fuente, C. de León, P. Desiati, N. Di Lalla, R. Diaz Hernandez, M.A. DuVernois, J.C. Díaz-Vélez, K. Engel, T. Ergin, C. Espinoza, N. Fraija, S. Fraija, A. Galván-Gámez, J.A. García-González, F. Garfias, N. Ghosh, A. Gonzalez Muñoz, M.M. González, J.A. González, J.A. Goodman, J. Gyeong, J.P. Harding, S. Hernández-Cadena, I. Herzog, D. Huang, F. Hueyotl-Zahuantitla, P. Hüntemeyer, A. Iriarte, S. Kaufmann, D. Kieda, K. Leavitt, W.H. Lee, J. Lee, H. León Vargas, J.T. Linnemann, A.L. Longinotti, G. Luis-Raya, C. Lundy, K. Malone, O. Martinez, J. Martínez-Castro, H. Martínez-Huerta, J.A. Matthews, P. Miranda-Romagnoli, P.E. Mirón-Enriquez, J.A. Morales-Soto, E. Moreno, M. Mostafá, M. Najafi, A. Nayerhoda, L. Nellen, M.U. Nisa, R. Noriega-Papaqui, N. Omodei, E. Ponce, Y. Pérez Araujo, E.G. Pérez-Pérez, C.D. Rho, A. Rodriguez Parra, D. Rosa-González, M. Roth, H. Salazar, D. Salazar-Gallegos, A. Sandoval, M. Schneider, J. Serna-Franco, M. Shin, A.J. Smith, Y. Son, R.W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, F. Ureña-Mena, E. Varela, L. Villaseñor, X. Wang, Z. Wang, I.J. Watson, H. Wu, S. Yu, X. Zhang, H. Zhou

Astrophysics of Galaxies

Tracing AGN Feedback Power with Cool/Warm Outflow Densities: Predictions and Observational Implications

Ivan Almeida, Tiago Costa, Chris M. Harrison et al. (+1 more)

Winds launched at the scale of the accretion disc or dusty torus in Active Galactic Nuclei (AGN) are thought to drive energy-conserving outflows that shape galaxy evolution. The key signature of such outflows, the presence of a hot ($T \gtrsim 10^9 \, \rm K$), shocked wind component, is hard to detect directly. Observations of AGN outflows typically probe a separate outflow phase: cool/warm gas with $T \lesssim 10^5 \, \rm K$. Here, we show that the density of cool outflowing gas scales with AGN luminosity, serving as an indirect diagnostic of the elusive hot, shocked wind. We use hydrodynamic simulations with the moving-mesh code AREPO to target the interaction between a small-scale AGN wind of speed $\approx 10^4 \, \rm km \, s^{-1}$ and galactic discs containing an idealised, clumpy interstellar medium (ISM). Through a new refinement scheme targeting rapidly-cooling, fast-moving gas, our simulations reach a resolution of $\lesssim 0.1 \, \rm pc$ in the cool, outflowing phase. We extract an ensemble of cool clouds from the AGN-driven outflows produced in our simulations, finding that their densities increase systematically with AGN wind power and AGN luminosity. Moreover, the mass distribution and internal properties of these cloudlets appear to be insensitive to the initial properties of the ISM, and shaped mainly by the dynamics of radiative, turbulent mixing layers. The increase in cool outflow density with kinetic wind power and AGN luminosity has profound implications for observational estimates of outflow rates and their scaling with AGN luminosity. Depending on the available outflow and density tracers, observationally-derived outflow rates may be overestimated by orders of magnitude.
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All authors Ivan Almeida, Tiago Costa, Chris M. Harrison, Samuel R. Ward

High Energy Astrophysical Phenomena

Long-term timing of the relativistic binary PSR J1906+0746

L. Vleeschower, B.W. Stappers, M. J. Keith et al. (+9 more)

We conducted a timing analysis of over 18 years of data on the young ($\tau_{\rm c} = 112$ kyr, $P = 114$\,ms) relativistic binary PSR~J1906+0746, using six radio telescopes: Arecibo, FAST, Green Bank, Lovell, MeerKAT, and Nançay. This pulsar is known to orbit a compact high-mass companion with a period of 3.98\,hrs in a mildly eccentric orbit ($e = 0.085$). By combining all data and maintaining a coherent timing solution over the full span, we obtained a more precise measurement of the advance of periastron, $\dot{\omega} = 7.5841(2)$\,$\deg$\,yr$^{-1}$, the Einstein delay, $\gamma = 4.59(2) \times 10^{-4}$\,s, and the secular change in orbital period, $\dot{P}_{\rm b} = -5.65(2) \times 10^{-13}$\,s\,s$^{-1}$. Assuming the validity of general relativity, we obtain a total mass of 2.6133(1)\,$M_{\odot}$ and component masses of 1.316(5) $M_{\odot}$ for the pulsar and 1.297(5) $M_{\odot}$ for the companion, consistent with a double neutron star system. However, when fitting for the secular change in the projected semi-major axis we obtain $\dot{x} = -1.8(6) \times 10^{-13}$\,s\,s$^{-1}$, the component masses are shifted by $\sim 3.5\sigma$, which is expected from the correlation of $\dot{x}$ and $\gamma$. The $\dot{x}$ has a similar magnitude to that observed in PSR~J1141$-$6545, which is due to spin-orbit coupling; if confirmed, it would indicate that, as in the latter system, the companion of the PSR~J1906+0746 system is a massive fast-rotating white dwarf formed before the pulsar. Additionally, we report and characterize a large glitch near MJD 56664, with a fractional frequency increase comparable to those observed in the Vela pulsar.
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All authors L. Vleeschower, B.W. Stappers, M. J. Keith, G. Desvignes, P. C. C. Freire, M. Kramer, J. van Leeuwen, L. Levin, A. G. Lyne, I. H. Stairs, V. Venkatraman Krishnan, Y. Y. Wang

Astrophysics of Galaxies

The JWST EXCELS survey: The ages and abundances of $3<z<5$ massive quiescent galaxies show that downsizing was already in place by $z\simeq4$

Ho-Hin Leung, Adam C. Carnall, Elizabeth Taylor et al. (+21 more)

We present deep, medium-resolution $\lambda=1-5\,\mu$m JWST/NIRSpec spectroscopy for 14 quiescent galaxies at $3<z<5$ with $\log_{10}(M_*/\mathrm{M_\odot}){\,>\,}10$, obtained as part of the EXCELS survey. We perform a complete re-reduction of these data, including a custom optimal-extraction approach to combat the spectral "wiggles" that result from undersampling of the NIRSpec spatial PSF. We constrain the star-formation histories and stellar metallicities of these objects via full-spectral fitting, finding a clear stellar age vs stellar mass correlation, in which more massive galaxies assembled their stellar mass at earlier times. This confirms spectroscopically that the archaeological "downsizing" trend was already in place by $z\simeq4$. The slope of our measured relation ($\simeq2$ Gyr per dex in stellar mass) is consistent with literature results at $0 < z < 3$. We do not observe objects with $\log_{10}(M_*/\mathrm{M_\odot})\lesssim10.5$ and ages of more than a few hundred Myr at this epoch, suggesting that recently reported examples of higher-redshift quiescent galaxies at these masses are likely to soon rejuvenate. We measure relatively high stellar metallicities for the majority of our sample, consistent with similar objects at $0 < z < 3$. Finally, we explore evidence for $\alpha$-enhancement in six older and more luminous galaxies within our sample, finding considerable disagreements in the chemical abundances measured using different stellar population models, different fitted rest-frame wavelength ranges, star-formation history models and fitting codes. We therefore conclude that inferring detailed stellar chemical abundances for the earliest quiescent galaxies remains challenging, and higher signal-to-noise spectra are required (SNR per resolution element $>100$ for $R\simeq1000$).
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All authors Ho-Hin Leung, Adam C. Carnall, Elizabeth Taylor, Struan D. Stevenson, Aliza G. Beverage, Fergus Cullen, James S. Dunlop, Derek J. McLeod, Ross J. McLure, Ryan Begley, Omar Almaini, Stella Antonogiannaki, Karla Z. Arellano-Córdova, Laia Barrufet, Cecilia Bondestam, Callum T. Donnan, Isaac J. B. Holst, Feng-Yuan F. Liu, Kate Rowlands, Ryan L. Sanders, Dirk Scholte, Maya Skarbinski, Thomas M. Stanton, Vivienne Wild

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

deci-Hz Gravitational Wave Observations on the Moon and Beyond

Emanuele Berti, Marica Branchesi, Alessandra Buonanno et al. (+21 more)

This document summarizes talks and discussions from the workshop "deci-Hz Gravitational Wave Observations on the Moon and Beyond" that took place at Johns Hopkins University between September 1 and September 3, 2025. The workshop focused on experimental proposals to observe gravitational waves in the deci-Hz band, including lunar detectors, laser interferometers in space, and atom interferometry; gravitational wave sources in the deci-Hz frequency band; and the multi-messenger and multi-band astronomy that would be enabled by these observations.
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All authors Emanuele Berti, Marica Branchesi, Alessandra Buonanno, Alessandra Corsi, Daniel J. D'Orazio, Jan Harms, Jason M. Hogan, Francesco Iacovelli, Karan Jani, Marc Kamionkowski, Kentaro Komori, Konstantinos Kritos, Andrea Maselli, M. Coleman Miller, Chiara M. F. Mingarelli, Volker Quetschke, B. S. Sathyaprakash, David H. Shoemaker, Joseph Silk, Jacob P. Slutsky, James Ira Thorpe, James Trippe, Daniele Vetrugno, Stefano Vitale

Cosmology and Nongalactic Astrophysics

Early growth of massive black holes in dynamical dark energy models with negative cosmological constant

N. Menci, M. Castellano, P. Mukherjee et al. (+4 more)

Recent results from combined cosmological probes indicate that the Dark Energy component of the Universe could be dynamical. The simplest explanation envisages the presence of a quintessence field rolling into a potential, where the Dark Energy energy density parameter $\Omega_{DE}=\Omega_{\Lambda}+\Omega_{x}$ results from the contribution of the ground state energy $\Omega_{\Lambda}$ and the scalar field energy $\Omega_{x}$. Provided that $\Omega_{DE}\approx 0.7$, negative values of $\Omega_{\Lambda}$ can be consistent with current measurements from cosmological probes, and could help in explaining the large abundance of bright galaxies observed by JWST at $z> 10$, largely exceeding the pre-JWST expectations in a $\Lambda CDM$ Universe. Here we explore to what extent such a scenario can account also for the early presence of massive Black Holes (BHs) with masses $M_{BH}\gtrsim 10^7\,M_{\odot}$ observed at $z\gtrsim 8$, and for the large over-abundance of AGN with respect to pre-JWST expectations. Our aim is not to provide a detailed description of BH growth, but rather to compute the maximal BH growth that can occur in cosmological models with negative $\Omega_{\Lambda}$ under the simple assumption of Eddington-limited accretion onto initial light Black Hole seeds with mass $M_{seed}\sim 10^2\,M_{\odot}$ originated from PopIII stars. To this aim we develop a simple analytic framework to connect the growth of dark matter halos to the maximal growth of BHs within the above assumptions. We show such models can account for present observations assuming values of $\Omega_{\Lambda}\approx -1$, simultaneously boosting both galaxy and AGN number counts without invoking any additional physics. This would allow us to trace the observed excess of bright and massive galaxies and the early formation of massive Black Holes and the abundance of AGN to the same cosmological origin.
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All authors N. Menci, M. Castellano, P. Mukherjee, D. Roberts, P. Santini, A.A. Sen, F. Shankar

Earth and Planetary Astrophysics

The Effects of Non-ideal Mixing in Planetary Magma Oceans and Atmospheres

Aaron Werlen, Edward D. Young, Hilke E. Schlichting et al. (+2 more)

Sub-Neptunes with hydrogen-rich envelopes are expected to sustain long-lived magma oceans that continuously exchange volatiles with their overlying atmospheres. Capturing these interactions is key to understanding the chemical evolution and present-day diversity of sub-Neptunes, super-Earths, and terrestrial planets, particularly in light of new JWST observations and upcoming missions. Recent advances in both geochemistry and astrophysics now allow the integration of experimental constraints and thermodynamic models across melt, metal, and gas phases. Here we extend a global chemical equilibrium model to include non-ideal behavior in all three phases. Our framework combines fugacity corrections for gas species with activity coefficients for silicate and metal species, enabling a fully coupled description of volatile partitioning. We show that for planetary embryos (0.5 M$_\oplus$ at 2350 K), non-ideality introduces only modest corrections to atmosphere-magma ocean interface (AMOI) pressures, volatile inventories, and interior compositions. In contrast, for sub-Neptunes with higher temperatures ($\approx$ 3000 K) and pressures, non-ideal effects are more pronounced, though still modest in absolute terms$-$typically within 20% and at most a factor of two. Including activity and fugacity coefficients simultaneously increases the AMOI pressure, enhances water retention in the mantle and the envelope. Our results demonstrate that non-ideality must be treated globally: applying corrections to only one phase leads to incomplete or even misleading trends. These findings highlight the importance of self-consistent global thermodynamic treatments for interpreting atmospheric spectra and interior structures of sub-Neptunes and super-Earths.
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All authors Aaron Werlen, Edward D. Young, Hilke E. Schlichting, Caroline Dorn, Anat Shahar

Cosmology and Nongalactic Astrophysics

Predicting galaxy bias using machine learning

Catalina Riveros-Jara, Antonio D. Montero-Dorta, Natália V. N. Rodrigues et al. (+6 more)

Understanding how galaxies trace the underlying matter density field is essential for characterizing the influence of the large-scale structure on galaxy formation, being therefore a key ingredient in observational cosmology. This connection, commonly described through the galaxy bias, $b$, can be studied effectively using machine learning (ML) techniques, which offer strong predictive capabilities and can capture non-linear relationships. We aim to incorporate the linear bias parameter assigned to individual galaxies into a ML framework, quantify its dependence on various halo and environmental properties, and evaluate whether different algorithms can accurately predict this parameter and reproduce the scatter in several bias relations. We use data from the IllustrisTNG300 simulation, including the distance to different cosmic-web structures computed with DisPerSE. These data are complemented with an object-by-object estimator of the large-scale linear bias ($b_i$), providing the individual contribution of each galaxy to the bias of the entire population. Our ML framework uses three models to predict $b_i$: a Random Forest Regressor, a Neural Network and a probabilistic method (Normalizing Flows). We recover the full hierarchy of galaxy bias dependencies, showing that the most informative features are the overdensities, particularly $\delta_8$, followed by the distances to cosmic-web structures and selected internal halo properties, most notably $z_{1/2}$. We also demonstrate that Normalizing Flows clearly outperform deterministic methods in predicting galaxy bias, including its joint distributions with galaxy properties, owing to their ability to capture the intrinsic variance associated with the stochastic nature of the matter-halo-galaxy connection. Our ML framework provides a foundation for future efforts to measure individual bias with upcoming spectroscopic surveys.
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All authors Catalina Riveros-Jara, Antonio D. Montero-Dorta, Natália V. N. Rodrigues, Pía Amigo, Natalí S. M. de Santi, Andrés Balaguera-Antolínez, Raul Abramo, Neill Guzmán, M. Celeste Artale

Cosmology and Nongalactic Astrophysics

Microlensing constraints on Primordial Black Hole abundance with Subaru Hyper Suprime-Cam observations of Andromeda

Sunao Sugiyama, Masahiro Takada, Naoki Yasuda et al. (+1 more)

We present updated microlensing analysis results based on high-cadence ($\sim$2~min) Subaru Hyper Suprime-Cam (HSC) observations of the Andromeda Galaxy (M31) in 2014, 2017, and 2020, yielding a total of 39.3 hours of data. We use a point-lens finite-source model for the microlensing light curve model and employ multi-stage selection procedures to identify microlensing candidates. From more than 25,000 variable candidates detected across all nights, we identify 12 microlensing candidates with light-curve timescales shorter than 5~hours, and among them, 4 secure candidates with high-significance detections. We estimate detection efficiencies using light-curve-level simulations that account for observational conditions and finite-source effects. Using a hierarchical Bayesian framework that combines the light-curve fitting information for each candidate with the Poisson statistics of the number of candidates, we derive constraints on parameters that characterize the abundance and mass scale of primordial black hole (PBH) dark matter. First, we derive upper limits on the PBH abundance under the null hypothesis that all events are assumed to be false detections. Next, employing the PBH hypothesis in which all (or only secure) candidates are assumed to be due to PBH microlensing, we derive the allowed region of the PBH parameters; the inferred mass scale is $M_{\rm PBH}\sim10^{-7}$–$10^{-6}M_\odot$, and the PBH abundance to the total dark matter is $f_{\rm PBH}\sim 10^{-1}$. Our results demonstrate that HSC-M31 monitoring remains a uniquely powerful probe of PBHs, and highlight the need for further studies for example, using Rubin Observatory LSST observations of the Large Magellanic Cloud.
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All authors Sunao Sugiyama, Masahiro Takada, Naoki Yasuda, Nozomu Tominaga

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

Mesoscopic chemical potentials across the (hyper)nuclear landscape

Jacquelyn Noronha-Hostler

Finite nuclei constrain the dense-matter equation of state (EOS), yet they are self-bound quantum droplets far from the thermodynamic limit. Motivated by an analogy to quantum dots, we show that the nuclear chart nevertheless defines a mesoscopic regime in which mesoscopic chemical-potential analogs $\{\mu_B,\mu_Q,\mu_S\}$ can be extracted directly from nuclear and hypernuclear binding energies after consistent Coulomb subtraction. These are discrete finite-difference response functions – local slopes of the strong-interaction energy landscape – not equilibrium grand-canonical chemical potentials. The nuclear chart itself supplies an "ensemble of nearby droplets": finite differences across neighboring nuclei suppress shell- and pairing-scale oscillations while retaining the smooth bulk trend, producing robust slopes without a macroscopic limit. Thus, the data provide empirical local derivatives that any strangeness-enabled EOS must reproduce near saturation. Mapping the measured (hyper)nuclear landscape at $T\simeq 0$, we find smooth, numerically stable responses, including a large, negative strangeness chemical-potential analog, and we identify specific hypernuclear measurements that can directly test and sharpen these EOS constraints.
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Solar and Stellar Astrophysics

Photometric variability of nitrogen-rich Wolf-Rayet stars in Magellanic Clouds with OGLE

Jana Marković, Guadalupe Sáez-Cano, Yaël Nazé et al. (+3 more)

We present a comprehensive analysis of the photometric variability of (presumably single) nitrogen-rich Wolf-Rayet (WN) stars in the Magellanic Clouds, using long-term observations from the OGLE survey. Our sample comprises 47 stars with no nearby Gaia counterparts. We characterize both overall and short-term variabilities, examining data dispersion and identifying periodicities. To validate our findings, we also compare the OGLE light curves with data from the MACHO and TESS missions. Variability is ubiquitous in our WR sample: about one third of stars display high variability, or four fifths if we include cases with moderate variations. The observed changes are found to be periodic in 11 cases, with timescales of 2-56 d. Such periodic variations originate in corotating wind structures, binary effects, or pulsations, thereby increasing the number of systems known to show these phenomena. Surprisingly, nine targets display (quasi-periodic) outbursts, making such changes a new type of WR variability. The variability shows a transient character, in about 30$\%$ of the sample, with changing amplitudes for periodic signals or for outbursts (they even sometimes completely disappear from view). Finally, we identified six long-period variables, four of which have been confirmed by at least two independent surveys.
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All authors Jana Marković, Guadalupe Sáez-Cano, Yaël Nazé, María del Mar Rubio-Díez, Igor Soszyński, Andrzej Udalski

Instrumentation and Methods for Astrophysics

Bayesian imaging inverse problem with scattering transform

Sébastien Pierre, Erwan Allys, Pablo Richard et al. (+2 more)

Bayesian imaging inverse problems in astrophysics and cosmology remain challenging, particularly in low-data regimes, due to complex forward operators and the frequent lack of well-motivated priors for non-Gaussian signals. In this paper, we introduce a Bayesian approach that addresses these difficulties by relying on a low-dimensional representation of physical fields built from Scattering Transform statistics. This representation enables inference to be performed in a compact model space, where we recover a posterior distribution over signal models that are consistent with the observed data. We propose an iterative adaptive algorithm to efficiently approximate this posterior distribution. We apply our method to a large-scale structure column density field from the Quijote simulations, using a realistic instrumental forward operator. We demonstrate both accurate statistical inference and deterministic signal reconstruction from a single contaminated image, without relying on any external prior distribution for the field of interest. These results demonstrate that Scattering Transform statistics provide an effective representation for solving complex imaging inverse problems in challenging low-data regimes. Our approach opens the way to new applications for non-Gaussian astrophysical and cosmological signals for which little or no prior modeling is available.
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All authors Sébastien Pierre, Erwan Allys, Pablo Richard, Roman Soletskyi, Alexandros Tsouros

Astrophysics of Galaxies

MIGHTEE/COSMOS-3D: The discovery of three spectroscopically confirmed radio-selected star-forming galaxies at z=4.9-5.6

R. G. Varadaraj, A. Saxena, S. Fakiolas et al. (+10 more)

Radio observations offer a dust-independent probe of star formation and active galactic nucleus (AGN) activity, but sufficiently deep data are required to access the crossover luminosity between these processes at high redshift ($z>4.5$). We present three spectroscopically confirmed high-redshift radio sources (HzRSs) detected at 1.3 GHz at $z=4.9$-$5.6$, with radio luminosities spanning $L_{\rm 1.3 \, GHz}\approx2$-$5\times10^{24} \, \rm W \, Hz^{-1}$. These sources were first identified as high-redshift candidates through spectral energy distribution (SED) fitting of archival Hubble, JWST NIRCam+MIRI, and ground-based photometry, and then spectroscopically confirmed via the $\rm H\,\alpha$ emission line using wide-field slitless spectroscopy from JWST COSMOS-3D. The star formation rates (SFRs) measured from SED fitting, the $\rm H\,\alpha$ flux, and the 1.3 GHz luminosity, span $\sim100$-$1800\, M_{\odot} \, \rm yr^{-1}$, demonstrating broad agreement between these SFR tracers. We find that these three sources lie either on or $0.5$-1.0 dex above the star-forming main sequence at $z=4$-6 and have undergone a recent burst of star formation. The sources have extended rest-UV/optical morphologies with no evidence for a dominant point source component, indicating that an AGN is unlikely to dominate their rest-UV and optical emission. Two of the sources have complex, multi-component rest-frame UV/optical morphologies, suggesting that their starbursts may be triggered by merging activity. These HzRSs open up a new window towards probing radio emission powered by star formation alone at $z> 4.5$, representing a remarkable opportunity to begin tracing star formation, independent of dust, in the early Universe.
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All authors R. G. Varadaraj, A. Saxena, S. Fakiolas, I. H. Whittam, M. J. Jarvis, R. A. Meyer, C. L. Hale, K. Kakiichi, M. Li, J. B. Champagne, B. Jin, Z. J. Li, M. Shuntov

Instrumentation and Methods for Astrophysics

Momentum-conserving self-gravity in the Phantom. Parallel dual tree traversal for the fast multipole method

Yann Bernard, Timothée David-Cléris, Daniel J. Price et al. (+1 more)

Tree codes that approximate groups of distant particles with multipole expansions accelerate gravitational force calculations. While momentum-conserving fast multipole methods exist, parallelisation is non-trivial inside a modern SPH framework. We aim for a parallel momentum and angular momentum-conserving Cartesian multipole method for the computation of the gravitational force in smoothed particle hydrodynamics (SPH) with adaptive gravitational force softening in Phantom. We modified Dehnen's original dual tree traversal algorithm to fit the parallel architecture of Phantom by replicating the node-node interaction on the ancestors of each leaf node in the tree. While this notionally duplicates work, it greatly simplifies the parallelisation of the algorithm. We then recover the $\mathcal{O}(N)$ scaling of the algorithm by use of caches. We also adapt the tree opening criterion for adaptive softening lengths, such that all interactions within the softening kernel are handled pairwise (as in SPH) rather than with multipole expansions, also allowing the gravity calculation to be performed alongside the SPH force evaluation. We demonstrate that the new code conserves linear and angular momentum to machine precision while giving similar force accuracy and better computational performance to the previous (non-symmetric) self-gravity solver in Phantom. Our new fast multipole method is now the default for computing self-gravity in the public code.
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All authors Yann Bernard, Timothée David-Cléris, Daniel J. Price, Mike Y. M. Lau

High Energy Astrophysical Phenomena

Relativistic Dynamics and Bondi-Hoyle-Lyttleton Accretion onto Rotating Embedded Black Hole Models

Asifa Ashraf, Orhan Donmez, Abdelmalek Bouzenada et al. (+4 more)

In this paper, we examine the motion of test particles and relativistic accretion mechanisms within the spacetime of a rotating and embedded BH. In this case, the geometric properties of the metric and their dynamical consequences for particle trajectories are systematically studied, with a specific focus on circular orbits together with their existence criteria and stability constraints. Also, the effective potential and the corresponding effective force are constructed to quantify the influence of rotation and embedding parameters on the attractive and repulsive sectors of the gravitational interaction. Closed-form expressions for orbital frequencies as measured by a distant observer are derived, enabling a quantitative analysis of relativistic precession phenomena, including periastron advance and Lense-Thirring precession. Furthermore, we conduct general-relativistic hydrodynamic simulations of BHL accretion onto rotating embedded BHs. In addition, within the framework of the BHL accretion mechanism, the numerical solution of the GRH equations shows that the embedding parameter \alpha systematically modifies the morphology of the shock cone formed around embedded BHs compared to the Kerr model. In particular, a wider opening angle of the cone is produced, the compression of matter in the post-shock region is weakened, and the dynamical variability of the flow is enhanced. The time-dependent mass accretion rate exhibits increasing oscillation amplitudes and long-term variations with increasing \alpha, while these amplitudes are found to be suppressed by the frame-dragging effect associated with the BH spin parameter. At the same time, increasing values of $\alpha$ lead to a strengthening of the QPO frequencies formed around embedded BHs in the LFQPO regime, enhancing their observability and increasing the likelihood of detecting commensurate frequency ratios such as 3:2.
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All authors Asifa Ashraf, Orhan Donmez, Abdelmalek Bouzenada, Chengxun Yuan, Aylin Caliskan, Gulzoda Rakhimova, Ahmadjon Abdujabbarov