High Energy Astrophysical Phenomena
Spectrum and anisotropies of Galactic cosmic rays: a laboratory for magnetic fields
Philipp Mertsch
Much has been learned about
Galactic cosmic rays in the past decade: On the observational side, the spectra of
cosmic ray
nuclei have been directly measured with high precision, resolving chemical composition up to TV
rigidities. At even higher
rigidities, direct detection is making contact with indirect observations from air shower arrays. A number of breaks have been found in the
nuclear spectrum, which was previously thought to be a pure power law up to the knee. Data from air shower arrays also show interesting features in the arrival directions of
cosmic-ray
nuclei. On the theoretical side, more sophisticated models are able to explain the various spectral breaks either with transitions between different classes of sources or with changes in the transport regime. Yet, it has become clear that our ignorance of the structure of the
Galactic magnetic fields, both on large and small scales, is limiting precision predictions. Turning this problem into an opportunity though, we can use
Galactic cosmic rays as a laboratory for the study of
Galactic magnetic fields. In this review talk, delivered at the 39th International
Cosmic Ray Conference (ICRC2025), I have summarised what is known about the spectrum and anisotropies of
Galactic cosmic rays, what is not known yet and what can be learnt in the future.
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Astrophysics of Galaxies
The critical role of clumping in line-driven disc winds
Amin Mosallanezhad, Christian Knigge, Nicolas Scepi et al. (+4 more)
Radiation pressure on spectral lines is a promising mechanism for powering disc winds from accreting white
dwarfs (AWDs) and active
galactic nuclei (AGN). However, in radiation-hydrodynamic simulations, overionization reduces line opacity and quenches the line force, which suppresses
outflows. Here, we show that small-scale clumping can resolve this problem. Adopting the microclumping approximation, our new simulations demonstrate that even modest volume filling factors ($f_V \sim 0.1-0.01$) can dramatically increase the wind mass-loss rate by lowering its ionization state – raising $\dot{M}_{\rm wind}$ and yielding $\dot{M}_{\rm wind}/\dot{M}_{\rm acc}\!\gtrsim\!10^{-4}$ for such modest filling factors. Clumpy wind models produce the UV resonance lines that are absent from smooth wind models. They can also reprocess a significant fraction of the disc luminosity and thus dramatically modify the broad-band optical/UV SED. Given that theory and observations indicate that disc winds are intrinsically inhomogeneous, clumping offers a physically motivated solution. Together, these results provide the first robust, self-consistent demonstration that clumping can reconcile line-driven wind theory with observations across AWDs and AGNs.
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All authors Amin Mosallanezhad, Christian Knigge, Nicolas Scepi, Knox S. Long, James H. Matthews, Stuart A. Sim, Austen Wallis
Earth and Planetary Astrophysics · Cross-listed from math.AP
Geophysical intensity problems: the axisymmetric case
Ralf Kaiser
Considering the earth or any other celestial body the main sources of the gravitational as well as of the
magnetic field lie inside the body. Above the surface both fields are in good approximation harmonic vector fields determined by their values at the body's surface or any other surface enclosing the body. The intensity problem seeks to determine harmonic vector fields vanishing at infinity and with prescribed intensity of the field at the surface. This problem constitutes a nonlinear boundary value problem, whose general solvability is not yet established. In this paper axisymmetric harmonic fields ${\bf H}$ outside the unit sphere $S^2$ are studied and, given an axisymmetric Hölder continuous intensity function $I\neq 0$ on $S^2$, the existence of infinitely many solutions of the intensity problem is proved. These solutions can more precisely be characterized as follows: fix a number $\de \in \nat\setminus \{1 \}$ and a meridional plane $M$ through the
symmetry axis $S\!A$, and in $M$ a unit circle $S^1$ (symmetric with respect to $S\!A$) and, furthermore, $2\, N$, $N \in \nat_0$, points $z_n \in M$ (symmetric with respect to $S\!A$, avoiding $S\!A$, and outside $S^1$), then the existence of an (up to a sign) unique harmonic field ${\bf H}$ is established that vanishes at (the axisymmetric circles piercing $M$ at) $z_n$ and nowhere else, that has intensity $I$ at $S^2$ and (exact) decay order $\de$ at infinity. The proof is based on the solution of a nonlinear
elliptic equation with discontinuous coefficients, which are, moreover, singular at the
symmetry axis. Its combination with fixed boundary conditions was the basis of a recent treatment of the “geomagnetic direction problem” \cite{KR22}. Here we have instead natural boundary conditions, which provide less information, and which require, therefore, in part new solution techniques and sharper estimates.
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Cosmology and Nongalactic Astrophysics
Inflationary relics from an Ultra-Slow-Roll plateau
Albert Escrivà, Jaume Garriga and Shi Pi
We investigate the formation of
primordial black holes (PBHs) in inflationary scenarios featuring an ultra-slow-roll (USR) plateau with a sharp transition to slow roll. We focus on two coexisting production channels: PBHs originating from relic
vacuum bubbles where the inflaton got trapped on the plateau, and PBHs arising from standard adiabatic density perturbations. From detailed numerical simulations we find that the bubbles are generically surrounded by type-II
curvature fluctuations. Special
attention is given to the distribution of initial conditions, including the relevant mean profiles and shape dispersion around them. For the adiabatic channel, we extend the logarithmic template formula $\zeta[\zeta_G]$, which maps the Gaussian
curvature perturbation to the fully non-Gaussian one while incorporating mode
evolution, and we compare this with numerical results obtained using the $\delta N$ formalism. While the template departs from numerical results near its logarithmic divergence, it still provides accurate threshold values for PBH formation in the parameter range relevant to our analysis. Finally, we compute the PBH mass functions for both channels. We find that the adiabatic channel dominates over the bubble-induced channel by a factor $\sim \mathcal{O}(10-10^{2})$, and that both contributions are largely dominated by the mean profiles.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Thermodynamics vs Teleodynamics: A Cosmological Divide?
Oem Trivedi and Venkat Venkatasubramanian
We show that stationary black holes and the evolving universe belong to fundamentally different thermodynamic regimes: black holes obey ordinary Bekenstein Hawking thermodynamics, whereas cosmology necessarily follows
memory-bearing teleodynamics. We show that teleodynamics is not valid for black holes, but is unavoidable in an expanding cosmology. This provides a dynamical, semi-classical realization of the thermodynamic split
conjecture and identifies
memory accumulation as the natural source of deviations from the area law in cosmology. Our results suggest that
quantum gravity should not seek to extrapolate black hole thermodynamics to the universe, but instead must incorporate horizon
memory as a fundamental microscopic ingredient and consider cosmological constructions consistent with that.
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High Energy Astrophysical Phenomena
Internal superfluid response and torque evolution in the giant glitch of PSR J1718-3718
Peng Liu, Zhonghao Tu, Jianping Yuan et al. (+1 more)
We investigate the post-glitch rotational
evolution of
pulsars by analyzing the 2007
giant glitch of PSR J1718$-$3718 using a
vortex creep model that incorporates both inward and outward nonlinear
vortex motion, along with a time-varying external torque. A comprehensive fitting framework is developed, constrained by prior knowledge of moment of inertia participation from previous glitch studies. We apply a Markov Chain Monte Carlo approach to quantify uncertainties and parameter correlations. The model reproduces the observed timing data and yields physically consistent values for moment of inertia fractions and creep timescales. Our results indicate that inward creep and a long-term change in external torque dominate the observed increase in
spin-down rate, pointing to structural changes within the
star-likely triggered by a crustquake that initiated both
vortex motion and a change in the moment of inertia. We estimate that the glitch involved approximately $2.4 \times 10^{12}$ inward-moving
vortices and $\sim 142$ crustal plates with a typical size of $\sim 0.03$ km. This study demonstrates that detailed post-glitch modeling of sparse timing data can simultaneously constrain internal superfluid dynamics and external torque
evolution, providing a quantitative framework to probe the structural properties of
neutron star interiors.
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All authors Peng Liu, Zhonghao Tu, Jianping Yuan, Ang Li
High Energy Astrophysical Phenomena
Intertwined birth and death: a Herbig-Haro outflow resolves the distance to Vela Junior
Janette Suherli, Ivo R. Seitenzahl, Samar Safi-Harb et al. (+8 more)
The distance to the Vela Junior
supernova remnant (RX J0852.0-4622 or G266.2-1.2) has long remained uncertain, limiting our understanding of its physical properties. Using VLT/MUSE integral field spectroscopy, we uncover chemical and kinematic connections between the nebula surrounding its Central Compact Object (CXOU J085201.4-461753) and the nearby Herbig-Haro
outflow of Ve 7-27 (Wray 16-30), indicating a shared nitrogen-rich, Fe-peak-enhanced environment. This link ties
stellar birth and death, with the young
star Ve 7-27 embedded in material expelled by Vela Junior's massive progenitor, and the remnant's blast wave is expanding through the same medium. Adopting the
Gaia-based distance to Ve 7-27, we revise Vela Junior's distance to $1.41\pm0.14$ kpc. At this distance, the remnant's physical radius is $23.3\pm2.3$ pc, and X-ray proper motions of the northwestern rim correspond to shock speeds of $(2.8\pm0.7)\times10^3$ to $(5.6\pm1.5)\times10^3$ km s$^{-1}$. These imply an age of $\sim$1.6-3.3 kyr and a very low ambient density, indicating that Vela Junior is expanding within a highly rarefied wind-blown cavity carved by a massive progenitor – consistent with the non-detection of strong thermal X-ray emission. This distance update also resolves long-standing inconsistencies, with major implications for its energy budget, particle acceleration efficiency, and compact object
evolution.
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All authors Janette Suherli, Ivo R. Seitenzahl, Samar Safi-Harb, Frédéric P. A. Vogt, Wynn C. G. Ho, Parviz Ghavamian, Chuan-Jui Li, Ashley J. Ruiter, Roland M. Crocker, Arpita Roy, Ralph Sutherland
High Energy Astrophysical Phenomena
MALLORN: Many Artificial LSST Lightcurves based on Observations of Real Nuclear transients
Dylan Magill, Matt Nicholl, Vysakh Anilkumar et al. (+10 more)
The Vera C. Rubin Observatory's 10-Year Legacy Survey of Space and Time (LSST) is expected to produce a hundredfold increase in the number of transients we observe. However, there are insufficient spectroscopic resources to follow up on all of the wealth of targets that LSST will provide. As such it is necessary to be able to prioritise objects for followup observations or inclusion in sample studies based purely on their LSST photometry. We are particularly keen to identify
tidal disruption events (TDEs) with LSST. TDEs are immensely useful for determining black hole parameters and probing our understanding of
accretion physics. To assist in these efforts, we present the Many Artificial LSST Lightcurves based on the Observations of Real
Nuclear transients (MALLORN) data set and the corresponding classifier challenge for identifying TDEs. MALLORN comprises 10178 simulated LSST light curves, constructed from real Zwicky Transient Facility (ZTF) observations of 64 TDEs, 727
nuclear supernovae and 1407 AGN with spectroscopic labels using Gaussian process fitting, empirically-motivated spectral energy distributions from SNCosmo and the baseline from the Rubin Survey Simulator. Our novel approach can be easily adapted to simulate transients for any photometric survey using observations from another, requiring only the limiting magnitudes and an estimate of the cadence of observations. The MALLORN Astronomical Classification Challenge, launched on Kaggle on 15/10/2025, will allow competitors to test their photometric classifiers on simulated LSST data to find TDEs and improve upon their capabilities prior to the start of LSST.
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All authors Dylan Magill, Matt Nicholl, Vysakh Anilkumar, Sjoert van Velzen, Xinyue Sheng, Thai Son Mai, Hung Viet Tran, Ngoc Phu Doan, Thomas Moore, Shubham Srivastav, David R. Young, Charlotte R. Angus, Joshua Weston
Earth and Planetary Astrophysics
Oxygen Isotope Constraints on the Importance of Photochemical Processing in Protoplanetary Disks
Fred J. Ciesla, Eric Van Clepper, Jennifer Bergner et al. (+1 more)
Observations have revealed evidence of photochemical processing in protoplanetary disks. This processing occurs in the
photon dominated layer, the optically thin regions of the disk high above the disk midplane. It remains unclear, however, how much this photochemical processing impacts the compositions of the
planets and their building blocks within the disk. Here we use the oxygen isotopic compositions of
Solar System solids, which has been attributed to photochemistry in the
solar nebula, to quantitatively evaluate whether this processing could have produced the conditions needed to provide the diversity of compositions seen in the
Solar System. We do this by modeling the chemical
evolution while fine
dust grows into the building blocks of the
planets. We find that the oxygen isotopic
evolution cannot be attributed to processing in the
solar nebula and must instead be inherited from the parent molecular cloud. Further, our results indicate that the observed photochemical processing in protoplanetary disks does not significantly impact the compositions of
planets that form within.
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All authors Fred J. Ciesla, Eric Van Clepper, Jennifer Bergner, Edwin Bergin
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Constraints on Genesis Cosmology from the Smeared Null Energy Condition
Dong-Hui Yu, Mian Zhu and Yong Cai
The violation of the null energy condition (NEC) is essential for constructing nonsingular cosmological scenarios, such as Genesis cosmology, which avoids the initial singularity by initiating
cosmic evolution from an asymptotically Minkowski state. To address theoretical concerns regarding the accumulation of negative energy, the smeared null energy condition (SNEC) has been proposed as a
quantum-motivated, semi-local bound on NEC violation. In this work, we examine the implications of the SNEC
conjecture for Genesis models, typically constructed within generalized Galileon theories. Our results demonstrate that SNEC imposes nontrivial restrictions on the viability of Genesis models, highlighting the SNEC
conjecture as a powerful tool for constraining nonsingular cosmological scenarios.
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Astrophysics of Galaxies
Long-term Mid-infrared Color Variations of Narrow-Line Seyfert 1 Galaxies
Jiahua Wu, Huifang Xie, Liming Dou et al. (+6 more)
We present a systematic investigation of long-term mid-infrared (MIR) color variability in 1,718 Narrow-Line Seyfert 1
galaxies (NLSy1s) using 14-year WISE/NEOWISE monitoring data. Through Pearson correlation analysis between photometric magnitude and color, we identify: (1) a
radio-quiet NLSy1 (RQ-NLSy1) population comprising 230 bluer-when-brighter (BWB) sources, 131 redder-when-brighter (RWB) sources, and 1,323 objects showing weak or statistically insignificant color variations; and (2) a
radio-loud NLSy1 (RL-NLSy1) population containing 5 BWBs, 2 RWBs, and 27 sources with weak/no color variations. Our analysis reveals that the BWB tendency strengthens significantly in
galaxies with redder mean MIR colors $\rm \left<W1-W2\right>$ and lower starlight contamination. Furthermore, this color-change pattern demonstrates that the most bolometric luminous sources exhibit the most pronounced BWB behavior. While similar trends exist for black hole mass and Eddington ratio, bolometric luminosity appears to be the primary physical driver. Potential origins of these variations (e.g., host
galaxy contribution,
accretion disk variability, and
dust reprocessing) are discussed. We conclude that temperature-dependent
dust reprocessing dominates the observed BWB, RWB, and no/weak variation patterns. This interpretation may also apply to similar MIR color variations observed in other extragalactic MIR transients, such as
tidal disruption events, ambiguous
nuclear transients, and changing-look AGNs. In addition, we find no significant difference in long-term MIR color variations between RL-NLSy1s and RQ-NLSy1s, however, RL-NLSy1s show significantly greater dispersion in intrinsic variability amplitude compared to RQ-NLSy1s due to jet-induced complexity, where non-thermal synchrotron emission from relativistic jets obscures thermal
dust signatures.
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All authors Jiahua Wu, Huifang Xie, Liming Dou, Yanli Ai, Tinggui Wang, Xinwen Shu, Ning Jiang, Luis C. Ho, Junhui Fan
Instrumentation and Methods for Astrophysics · Cross-listed from physics.optics
Adaptive Optics-Enhanced Michelson Interferometer for Spectroscopy of Narrow-Band Light Sources
Jesneil Lauren Lewis and Ayan Banerjee
Adaptive optics enables the deployment of interferometer-based spectroscopy without the need for moving parts necessary for scanning the interferometer arms. Here, we employ a Michelson Interferometer in conjunction with a Spatial Light Modulator (SLM) for determining the spectral profile of a narrow-band light source. Interestingly, we observe that the fringes across the interferometer output beam are inherently shifted in wavelength even when a constant phase profile is provided to the SLM. We calibrate the spectral shifts as a function of fringe spatial location by measuring the incident light spectrum at various points across the fringe pattern, and observe that the spectral peak traces out a `teardrop' shape, whose width is dependent on the spectral bandwidth of the source, the relative tilt and path difference between the two arms of the interferometer, and the divergence of the beam. Next, we demonstrate that this inherent spectral variation of the fringes can be used to perform fast single-snapshot spectroscopy of narrow-band light sources, while a time-varied phase profile provided to the SLM leads to multi-step spectroscopy with lower noise, higher resolution, and better contrast. Our findings establish that the Michelson Interferometer can be used to perform spectroscopy of any source within a certain spectral range from simple images of the fringe pattern, so as to facilitate exciting applications towards hyperspectral imaging.
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Solar and Stellar Astrophysics
Local mixing length theory with compositional effects:\ First application to asymptotic giant branch evolution
M.M. Ocampo, M.M. Miller Bertolami, A.H. Córsico et al. (+1 more)
During the
evolution of
stars on the asymptotic
giant branch (AGB), thermal pulses lead to the formation of strongly stratified layers in the outer regions of the CO core, which might lead to inversions in the chemical gradient. Such inversions would produce instabilities beyond the ones predicted by the Schwarzschild criterion and the standard use of mixing length theory (MLT). We used a set of MLT equations that consider the impact of the background chemical gradients. This extension of MLT is referred to in this work as MLT$\sharp$, to make a distinction between both prescriptions. We applied MLT$\sharp$ in tandem with the more general Ledoux instability criterion. We computed the
evolution in the AGB phase and compared the chemical profiles resulting from MLT, MLT$\sharp$ and the double diffusive GNA theory. We continued the
evolution through a post-AGB thermal pulse and performed a pulsational analysis of the resultant GW Vir models to asses $g$-mode pulsation periods. Finally, we tested our results with pulsation properties of known GW Vir
stars derived from recent observations. We find that the much simpler MLT$\sharp$ set of equations closely reproduces the results from the GNA theory. As such, MLT$\sharp$ offers a simple way to include chemically driven convection in
stellar evolution computations.
Stellar evolution simulations show that Rayleigh-Taylor and thermohaline instabilities can play an important role during the TP-AGB. We obtained significantly different chemical profiles using a standard MLT approach compared to those resulting from our MLT$\sharp$ and GNA computations. Our adiabatic pulsational analysis shows that these differences in the chemical stratification leave clear mode-trapping signatures in the pulsation spectrum of the GW Vir models.
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All authors M.M. Ocampo, M.M. Miller Bertolami, A.H. Córsico, L.G. Althaus
High Energy Astrophysical Phenomena
Probing TeV Afterglow Emission of GRB~221009A with Gaussian Structured jet in Wind-driven medium
T. Mondal, S. Chakraborty, L. Resmi et al. (+1 more)
Recent detections of very high energy (VHE; GeV-TeV)
photons from gamma-ray burst (GRB) afterglows, most notably the extreme event GRB 221009A, require refined models that include realistic jet structures and complex circumburst environments. The jet's angular structure is crucial for shaping afterglow emission. Our recent work demonstrates that Gaussian jets, with their smooth angular decline, naturally produce early bright peaks for on-axis observers and delayed, softer, dimmer peaks at higher inclinations. The gradual decline suppresses excessive lateral expansion, unlike the sharp edge in top-hat jets, making Gaussian jets a compelling alternative to both top-hat and other structured-jet models. Here we implement a Gaussian structured-jet model to explain TeV afterglows from adiabatic forward shocks propagating in a wind-driven medium. We show that the TeV peak time and flux depend sensitively on jet geometry, kinetic energy, wind density, and on microphysical parameter ratios that scale the SSC component. We identify the afterglow parameter space that is favourable for detecting sub-TeV
photons with the Cherenkov
Telescope Array (CTA), finding that only about ten per cent of simulated TeV events exceed CTA sensitivity in a wind medium. These detections arise from near core-aligned views, with high kinetic energy and wind density, moderate initial Lorentz factor and downstream
magnetic field, and a relatively large fraction of energy in nonthermal electrons. Applying this model to GRB 221009A, we perform multi-band fits including wind-modified dynamics, Klein-Nishina effects, and EBL attenuation, and find that a mildly off-axis geometry reproduces the observed X-ray and GeV-TeV light curves.
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All authors T. Mondal, S. Chakraborty, L. Resmi, D. Bose
Astrophysics of Galaxies
The MALATANG survey: star formation, dense gas, and AGN feedback in NGC 1068
Shuting Lin, Siyi Feng, Zhi-Yu Zhang et al. (+14 more)
We aim to investigate the interplay between dense molecular gas,
star formation, and active
galactic nucleus (AGN) feedback in the luminous infrared
galaxy (LIRG) NGC 1068 at sub-kiloparsec scales. We present the HCN (4-3) and HCO$^+$ (4-3) maps of NGC 1068, obtained with JCMT as part of the Mapping the dense molecular gas in the strongest
star-forming
galaxies (MALATANG) project, and perform spatially resolved analyses of their correlations with infrared luminosity and soft X-ray emission. Spatially resolved relations between the luminosities of infrared
dust emission and dense molecular gas tracers ($L_{\rm IR}-L'_{\rm dense}$) are found to be nearly linear, without clear evidence of excess contributions from AGN activity. The spatially resolved X-ray emission ($L^{\rm gas}_{0.5-2\,\mathrm{keV}}$) displays a radially-dependent twofold correlation with the
star formation rate (SFR), suggesting distinct gas-heating mechanisms between the
galaxy center and the outer regions. A super-linear scaling is obtained in
galactic center regions with SFR surface density ($\Sigma_{\rm SFR}$) $>$ 8.2 $\times$ 10$^{-6}$ $M_\odot$ yr$^{-1}$ kpc$^{-2}$: log($L^{\rm gas}_{0.5-2\,\mathrm{keV}}$/erg s$^{-1}$) = 2.2 log(SFR/$M_\odot$ yr$^{-1}$) + 39.1. We further found a statistically significant super-linear correlation ($\beta = 1.34$ $\pm$ 0.86) between $L^{\rm gas}_{0.5-2\,\mathrm{keV}}$/SFR and HCN(4-3)/CO(1-0) intensity ratio, whereas no such trend is seen for HCO$^+$(4-3)/CO(1-0) or CO(3-2)/CO(1-0). These findings indicate that AGN feedback does not dominate
star formation regulation on sub-kiloparsec scales, and that the excitation of dense gas traced by HCN (4-3) may be more directly influenced by high-energy feedback processes compared to HCO$^+$ (4-3) and CO (3-2).
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All authors Shuting Lin, Siyi Feng, Zhi-Yu Zhang, Chunyi Zhang, Qing-Hua Tan, Junzhi Wang, Yu Gao, Xue-Jian Jiang, Yang Gao, Xiao-Long Wang, Junfeng Wang, Jian-Fa Wang, Satoki Matsushita, Aeree Chung, Kotaro Kohno, Tosaki Tomoka, Thomas R. Greve
Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc
Detecting relativistic black hole collisions near a massive black hole
Yirong Fang, Changfu Shi and Jianwei Mei
Relativistic black hole collisions are one of the most dramatic astrophysical events that can be imagined. They could provide the ideal condition for searching for possible new physics beyond general relativity. However, such events are presumably rare and difficult to occur under normal conditions. Black holes in a triple system can be accelerated to the relativistic limit and may harbor the chance for a relativistic collision. In this paper, we study the relativistic black hole collisions in a massive black hole background and the capabilities of several current and future gravitational wave detectors in detecting such signals.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Chaotic Imprints in Gravitational Waves from Extreme-Mass-Ratio-Inspirals Embedded in Dark Matter Halo
Surajit Das, Surojit Dalui, Bum-Hoon Lee et al. (+1 more)
We investigate imprints of chaos in gravitational waves from extreme-mass-ratio inspirals configuration, where a
stellar massive object, confined in an external potential as a harmonic oscillators, orbits a supermassive Schwarzschild-like black hole embedded in a Dehnen-type dark matter
halo. In our previous work (Das S, et al., Extreme-mass-ratio inspirals embedded in dark matter
halo: Existence of homoclinic orbit and horizon-induced chaos, Sci. China-Phys. Mech. Astron. 69, 290413 (2026)), we demonstrated the system's transition from non-chaotic to chaotic dynamics by analyzing Poincaré sections, orbital
evolution, and Lyapunov exponents across different energies and dark matter
halo parameters. In this work, we compute the gravitational waveforms of the small celestial object along different chaotic and non-chaotic orbits by implementing the numerical kludge scheme. We further perform spectral analysis of the gravitational waveforms from such orbits. In particular, we show that when the system is in a chaotic state, the gravitational wave signals are characterized by broader frequency spectra with finite widths, irregular waveform modulations with comparatively large strain excursions for the chaotic trajectories considered here, together with modified energy-emission characteristics, distinctly differentiating them from the signals generated during the system's non-chaotic state. Furthermore, we discuss the potential detectability of these orbits for upcoming observatories like
Laser Interferometer Space
Antenna (LISA), TianQin, and Taiji, emphasizing the significant potential for detecting chaotic imprints in gravitational waves to substantially enhance our understanding of chaotic dynamics in black hole physics and the dark matter environments of
galactic nuclei.
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All authors Surajit Das, Surojit Dalui, Bum-Hoon Lee, Yi-Fu Cai
Instrumentation and Methods for Astrophysics
aim-resolve: Automatic Identification and Modeling for Bayesian Radio Interferometric Imaging
Richard Fuchs, Jakob Knollmüller, Jakob Roth et al. (+4 more)
Modern
radio interferometers deliver large volumes of data containing high-sensitivity sky maps over wide fields-of-view. These large area observations can contain various and superposed structures such as point sources, extended objects, and large-scale diffuse emission. To fully realize the potential of these observations, it is crucial to build appropriate sky emission models which separate and reconstruct the underlying astrophysical components. We introduce aim-resolve, an automatic and iterative method that combines the
Bayesian imaging
algorithm resolve with deep learning and clustering
algorithms in order to jointly solve the reconstruction and source extraction problem. The method identifies and models different astrophysical components in
radio observations while providing uncertainty quantification of the results. By using different model descriptions for point sources, extended objects, and diffuse background emission, the method efficiently separates the individual components and improves the overall reconstruction. We demonstrate the effectiveness of this method on synthetic image data containing multiple different sources. We further show the application of aim-resolve to an L-band (856 - 1712 MHz) MeerKAT observation of the
radio galaxy ESO 137-006 and other
radio galaxies in that environment. We observe a reasonable object identification for both applications, yielding a clean separation of the individual components and precise reconstructions of point sources and extended objects along with detailed uncertainty quantification. In particular, the method enables the creation of catalogs containing source positions and brightnesses and the corresponding uncertainties. The full decoupling of sky emission model and instrument response makes the method applicable to a wide variety of instruments or wavelength bands.
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All authors Richard Fuchs, Jakob Knollmüller, Jakob Roth, Vincent Eberle, Philipp Frank, Torsten A. Enßlin, Lukas Heinrich
Solar and Stellar Astrophysics
Long-term X-ray variability of the multiple-planet host L 98-59: Hints of an activity cycle
I. Pillitteri, S. Bellotti, S. Benatti et al. (+7 more)
High-energy irradiation in X-rays and UV (XUV) can transform the planetary atmospheres through photoevaporation and photochemistry. This is more crucial for M
stars, whose habitable zones for Earth-like
planets are located within a few percent of an AU. Transiting
exoplanets around M
dwarfs offer the opportunity to study their characteristics and habitability conditions. L 98-59 is an M3
dwarf hosting six Earth-like
planets, with two of them in the habitable zone of the
star. X-ray observations made in 2020 and 2021 detected significant
flares above a quiescent luminosity of 4-10 x 10^26 erg/s. We present the results from two short XMM-Newton observations of L 98-59, which are part of a monitoring survey to detect long-term X-ray variability and activity cycles. In October 2024 the X-ray quiescent luminosity of the
star was about 5.9 x 10^25 erg/s, and it was about 6.3 x 10^26 erg/s in February 2025. We speculate that in late 2024 the
star had a minimum of activity; in 2021 the
star was near a maximum of an activity cycle, and in 2025 it was at the middle of the cycle. We suggest a coarse estimate of the period of about 2 years and a peak-to-peak amplitude of about 10, which is the highest among the
stars with a known X-ray cycle other than the Sun. We also infer that even the outer
planet in the habitable zone, L 98-59f, is exposed to an X-ray dose between 100 and 1600 times the X-ray irradiation of the Earth in the XMM band.
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All authors I. Pillitteri, S. Bellotti, S. Benatti, S. Boro Saikia, A. García Muñoz, K. G. Kislyakova, A. Maggio, G. Micela, K. Vida, A. A. Vidotto
Instrumentation and Methods for Astrophysics
Spaceflight KID Readout Electronics for PRIMA
Thomas Essinger-Hileman, C. Matt Bradford, Patrick Brown et al. (+23 more)
We present the design and testing of a prototype multiplexing kinetic inductance detector (KID) readout electronics for the PRobe far-Infrared Mission for Astrophysics (PRIMA) space mission. PRIMA is a Probe-class astrophysics mission concept that will answer fundamental questions about the formation of planetary systems, the co-
evolution of
stars and supermassive black holes in
galaxies, and the rise of heavy elements and
dust over
cosmic time. The readout electronics for PRIMA must be compatible with operation at Earth-Sun L2 and capable of multiplexing more than 1000 detectors over 2.5 GHz bandwidth while consuming around 30 W per readout chain. The electronics must also be capable of switching between the two instruments, which have different readout bands: the hyperspectral imager (PRIMAger, 2.6-4.9 GHz) and the spectrometer (FIRESS, 0.4-2.4 GHz). The PRIMA readout electronics use high-heritage SpaceCube digital electronics with a build-to-print SpaceCube Mini v3.0 board using a radiation-tolerant Kintex KU060 field programmable gate array (FPGA) and a custom high-speed digitizer board, along with RF electronics that provide filtering and power conditioning. We present the driving requirements for the system, as well as the hardware, firmware, software, and system-level design that meets those requirements.
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All authors Thomas Essinger-Hileman, C. Matt Bradford, Patrick Brown, Sean Bryan, Jesse Coldsmith, Jennifer Corekin, Sumit Dahal, Thomas Devlin, Marc Foote, Draisy Friedman, Alessandro Geist, Jason Glenn, Christopher Green, Tracee Jamison-Hooks, Kevin Horgan, Jared Lucey, Philip Mauskopf, Lynn Miles, Sanetra Bailey Newman, Gerard Quilligan, Cody Roberson, Adrian Sinclair, Salman Sheikh, Eric Weeks, Christopher Wilson, Travis Wise
High Energy Astrophysical Phenomena
Unveiling gravitational waves from core-collapse supernovae with MUSE
Alessandro Veutro, Irene Di Palma, Marco Drago et al. (+4 more)
The core collapse of a massive
star at the end of its life can give rise to one of the most powerful phenomena in the Universe. Because of violent mass motions that take place during the explosion, core-collapse
supernovae have been considered a potential source of detectable gravitational waveforms for decades. However, their intrinsic stochasticity makes ineffective the use of modelled techniques such as matched filtering, forcing us to develop model independent technique to unveil their nature. In this work we present MUSE pipeline, which is based on a classification procedure of the time-frequency images using a Convolutional Neural Network. The network is trained on phenomenological waveforms that are built to mimic the main common features observed in numerical simulation. The method is finally tested on a representative 3D simulation catalog in the context of Einstein
Telescope, a third generation GW
telescope. Among the three detector geometries considered here, the 2L with a relative inclination of $45^\circ$ is the one achieving the best results, thus being able to detect a Kuroda2016-like waveform with an efficiency above $90\%$ at 50 kpc.
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All authors Alessandro Veutro, Irene Di Palma, Marco Drago, Pablo Cerdá-Durán, Robin van der Laag, Melissa López, Fulvio Ricci
Astrophysics of Galaxies
287,872 Supermassive Black Holes Masses: Deep Learning Approaching Reverberation Mapping Accuracy
Yuhao Lu, HengJian SiTu, Jie Li et al. (+4 more)
We present a population-scale catalogue of 287,872 supermassive black hole masses with high accuracy. Using a deep encoder-decoder network trained on optical spectra with reverberation-mapping (RM) based labels of 849
quasars and applied to all SDSS
quasars up to $z=4$, our method achieves a root-mean-square error of $0.058$\,dex, a relative uncertainty of $\approx 14\%$, and coefficient of determination $R^{2}\approx0.91$ with respect to RM-based masses, far surpassing traditional single-line virial
estimators. Notably, the high accuracy is maintained for both low ($<10^{7.5}\,M_\odot$) and high ($>10^{9}\,M_\odot$) mass
quasars, where empirical relations are unreliable.
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All authors Yuhao Lu, HengJian SiTu, Jie Li, Yixuan Li, Yang Liu, Wenbin Lin, Yu Wang
Solar and Stellar Astrophysics
Formation of the Dormant Black Holes with Luminous Companions from Binary or Triple Systems
Zhuowen Li, Xizhen Lu, Guoliang Lü et al. (+6 more)
Recently, a class of dormant black hole binaries with luminous companions (dBH-LC) has been observed, such as $Gaia$ BH1, BH2, and BH3. Unlike previously discovered X-ray BH binaries, this type of dBH-LC has relatively long orbital periods (typically more than several tens to a few hundred days) and shows very weak X-ray emission. Therefore, studying the formation and
evolution of the whole dBH-LC population is also a very interesting problem. Our aim is to study the contribution of massive
stars to the dBH-LC population under different evolutionary models (isolated binary
evolution (IBE) and hierarchical triple
evolution), and different formation channels (such as mass transfer, common envelope
evolution). Using the Massive Objects in Binary
Stellar Evolution (MOBSE) code, the Triple
Stellar Evolution (TSE) code, and the latest initial multiple-
star distributions, we model the populations of massive
stars. Finally, we calculate the orbital properties, mass distributions, and birthrates of the BH-LC populations formed under these different conditions. In the Milky Way, we calculate that the birthrate of dBH-LC formed through IBE is about 4.35$\times$$10^{-5}$ ${\rm yr}^{-1}$, while the birthrate through triple
evolution is about 1.47$\times$$10^{-3}$ ${\rm yr}^{-1}$. This means that the birthrate from triple
evolution is one to two orders of magnitude higher than that from IBE. We find that in triple
evolution, the main formation channel of dBH-LC is post-merger binaries formed from inner binary mergers triggered by von Zeipel$-$Lidov$-$Kozai oscillations.
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All authors Zhuowen Li, Xizhen Lu, Guoliang Lü, Chunhua Zhu, Helei Liu, Li Lei, Sufen Guo, Xiaolong He, Nurzada Beissen
Astrophysics of Galaxies
ALMA-QUARKS: Few-Thousand-Year Hatching out of "Egg": The Supersonic Breakout of a Hypercompact H II Region from Its Parental Hot Core
Siju Zhang, Guido Garay, Fengwei Xu et al. (+19 more)
The kinematic
evolution of hypercompact H II (HC H II) regions around young high-mass
stars remains poorly understood due to complex interactions with parental environs. We present ALMA
QUARKS/ATOMS 1.3 mm/3 mm observations (the highest resolution $\sim0.01$ pc) of a deeply embedded HC H II region (diameter $\sim0.015$ pc, electron density $\sim2\times10^{5}$ cm$^{-3}$) exhibiting a striking $\gtrsim20$ km s$^{-1}$ global
redshift seen in optically thin H30$\alpha$/H40$\alpha$ recombination lines relative to its parental hot molecular core within a hub-filament system. The 1.3 mm continuum data reveal a distinct 0.1-pc arc and a perpendicular 0.04-pc tail. We propose that this morphology arises from a dynamic champagne flow: the slow expansion of HC H II region into a pre-existing filament forms the arc and associated low-velocity (few km s$^{-1}$) SiO shocks. Meanwhile, in the opposite direction ionized gas escapes along a steep density gradient traced by the tail and high-velocity (20 km s$^{-1}$) SiO emission. We reject the bow shock scenario in which ionized gas co-moves with a runaway high-mass
star because shocked gas in the arc aligns with the hub velocity, contradicting the bow shock prediction. Non-LTE radiative transfer modeling further rules out infall of ionized gas as the velocity shift origin. We conclude that this exceptional HC H II region is undergoing a few-thousand-year transition phase of "hatching out of the egg": the ionized gas of HC H II region has just broken out of its parental hot core and now is flowing outward supersonically. This work highlights how anisotropic density distributions induce supersonically anisotropic ionized flows that govern HC H II region
evolution.
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All authors Siju Zhang, Guido Garay, Fengwei Xu, Luis F. Rodríguez, Neal J. Evans II, Annie Zavagno, Paul F. Goldsmith, Dongting Yang, Xunchuan Liu, Aiyuan Yang, Tie Liu, Amelia M. Stutz, Hong-Li Liu, Wenyu Jiao, Anandmayee Tej, Lei Zhu, Kee-Tae Kim, Pablo García, Thomas Peters, Thomas Möller, Shanghuo Li, Leonardo Bronfman
Solar and Stellar Astrophysics
On the magnetic field evolution of interplanetary coronal mass ejections from 0.07 to 5.4 au
Christian Möstl, Emma E. Davies, Eva Weiler et al. (+8 more)
A central question for understanding interplanetary coronal mass ejection (ICME) physics and improving space weather
forecasting is how ICMEs evolve in interplanetary space. We have updated one of the most comprehensive in situ ICME catalogs to date, which now includes 1976 events from 11 space missions covering over 34 years, from December 1990 to August 2025. We have combined existing catalogs including
magnetic obstacles and identified and added boundaries of an additional 807 (40.8%) events ourselves. With this catalog, we demonstrate the most extensive analysis to date of total ICME
magnetic field values as a function of heliocentric distance. Parker
Solar Probe has observed 6 ICMEs at $< 0.23$ au (until April 2025), and
Solar Orbiter and BepiColombo have added more events near 0.3 au, bridging the major observational gap towards the
solar corona. Our main result is that a single power law can describe the
evolution of the mean total
magnetic field (exponent value of $k=-1.57$) and maximum field ($k=-1.53$) for ICMEs with
magnetic obstacles (MOs), from 0.07 to 5.4 au. Extending the power law to the
solar photosphere reveals a strong inconsistency with
magnetic field magnitudes observed in the quiet Sun and active regions by 2 and 4 orders of magnitude, respectively. We introduce a multipole-type power law with two exponents, $k_1=-1.57$, and $k_2=-6$, relating the ICME
magnetic field magnitude to an average
solar active region field strength. These results present important observational constraints for the
evolution of ICMEs from the Sun to the heliosphere.
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All authors Christian Möstl, Emma E. Davies, Eva Weiler, Ute V. Amerstorfer, Andreas J. Weiss, Hannah T. Rüdisser, Martin A. Reiss, Satabdwa Majumdar, Timothy S. Horbury, Stuart D. Bale, Daniel Heyner
Earth and Planetary Astrophysics
The ejection velocities of interstellar objects signpost their progenitor system architectures
Leah Albrow, Michele T. Bannister, John C. Forbes et al. (+1 more)
Interstellar objects (ISOs) ejected from planetary systems carry kinematic signatures of their formation environments. The properties of these velocity distributions govern the ISOs' propagation and dynamical
evolution in the
Galactic potential. We investigate how planetary system architecture influences ISO production during post-gas-disc dynamical instabilities using N-body simulations. We explore the ISO production outcomes of 2461 randomly generated systems spanning total system masses of 300-800 Earth masses and multiplicities of 3-7
planets. By integrating
planets embedded in a disc of test particles for 10 Myr, we find that evolving systems can be broadly divided into two distinct classes based on their initial architectures. Catastrophic systems are characterized by high multiplicities and orbitally compact configurations, or by high-mass
planets in systems with large mass asymmetries. These systems eject a large fraction of their planetesimals (median 59 percent) and, depending on the ejection pathway, produce high-speed ISOs (median 2.9 km/s). In contrast, quiet systems have lower masses and multiplicities and do not undergo significant orbital rearrangement, yet still eject a median of 28 percent of planetesimals at lower velocities (median 1.6 km/s). This dichotomy points to distinct ejection pathways, involving either violent global instabilities or more gradual, diffusive processes. Overall, we find that ISO ejection velocities are typically low, on the order of a few km/s. Although ISOs subsequently experience dynamical heating as they orbit the
Galaxy, their velocity distributions retain signatures of their progenitor systems' architectures and histories, underscoring the potential use of ISOs in
Galactic archaeology.
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All authors Leah Albrow, Michele T. Bannister, John C. Forbes, David Nesvorný
Astrophysics of Galaxies
A Chandra view of SPT-CL J0217-5014: a massive galaxy cluster at a cosmic intersection at z=0.53
Dan Hu, Shida Fan, Zhongsheng Yuan et al. (+7 more)
Galaxy clusters trace the densest regions of the
cosmic web and are crucial laboratories for studying the thermodynamic and chemical
evolution of the intracluster medium (ICM). We present a Chandra study of the massive
galaxy cluster SPT-CL J0217-5014 ($z \sim 0.53$; $M_{\rm 500} \sim 3 \times 10^{14}~\rm M_{\odot}$), previously reported as a Swift serendipitous clusters with the highest Fe abundance ($\sim 1.3\pm 0.4$ $\rm Z_{\odot}$ within $\sim 1'.7$) and a potentially disturbed morphology. The X-ray morphology reveals a disturbed ICM with a surface brightness edge at $\sim 0'.26$ ($\sim 100$ kpc) to the west and a tail-like feature extending towards the east. The best-fit metal abundance within 1'.5 ($\sim 0.7\rm R_{500}$) is $0.61_{-0.23}^{+0.26}~\rm Z_{\odot}$. The derived central electron number density,
entropy, and cooling time classify this system as a non-cool-core cluster, suggesting that merger activity has likely disrupted the possible pre-existing cool core. At larger radii ($\sim 1' - 2'$), we detect excess X-ray emission to the south, spatially aligned with a filamentary distribution of red
galaxies, indicating ongoing
accretion along an intracluster filament. Based on the DESI DR9 cross-matched optical clusters and photometric
redshifts, we identify three nearby, lower-mass clusters that likely trace the large-scale structures, suggesting that SPT-CL~J0217-5014 is the primary node of a dynamically active environment where past mergers and anisotropic
accretion along
cosmic filaments have shaped the present-day ICM.
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All authors Dan Hu, Shida Fan, Zhongsheng Yuan, Junjie Mao, Norbert Werner, Yuanyuan Su, François Mernier, Yuanyuan Zhao, Liyi Gu, Haiguang Xu
Solar and Stellar Astrophysics
FAUST XXIX. OCS line emission: a new method for measuring the luminosity of embedded protostars in binary systems
Guillaume Saury, Vittorio Bariosco, Cecilia Ceccarelli et al. (+19 more)
The luminosity of embedded protostars is commonly measured via observations of the
dust continuum spectral energy distribution from millimetre to infrared wavelengths. However, this method cannot be applied to embedded protostars in binary or multiple systems, where their components are usually unresolved over this extended wavelength range. We propose a new method, based on the idea that a molecule formed (mainly) on the grain surfaces only emits lines in the region where it thermally sublimates from the grain mantles, heated by the
photons emitted by the embedded source. In this respect, carbonyl sulfide (OCS) is an optimal molecule, because of its low binding energy and rotational lines in the millimetre. We apply the method to the protobinary system NGC1333 IRAS4A, using ALMA high-spatial resolution ($\sim$50 au) observations of the OCS(19-18) line as part of the ALMA Large Program FAUST. We also present new
quantum mechanics calculations of the OCS binding energy distribution, essential for the application of the method. We found that the two binary components, A1 and A2, have a comparable luminosity within the error bars, 7.5$\pm$2.5 and 7$\pm$1 L$_\odot$, respectively. We discuss the reliability of the estimated luminosities and the potential of this new method for measuring the luminosity of embedded protostars in binary and multiple systems.
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All authors Guillaume Saury, Vittorio Bariosco, Cecilia Ceccarelli, Ana López-Sepulcre, Layal Chahine, Marta De Simone, Albert Rimola, Piero Ugliengo, Claire J. Chandler, Nami Sakai, Claudio Codella, Eleonora Bianchi, Lise Boitard–Crépeau, Mathilde Bouvier, Romane Le Gal, Laurent Loinard, Yoko Oya, Linda Podio, Giovanni Sabatini, Charlotte Vastel, Ziwei E. Zhang, Satoshi Yamamoto
Instrumentation and Methods for Astrophysics
Progress towards a microchannel plate detector with AlGaN photocathode and cross-strip anode for ultraviolet astronomy
S. Diebold, J. Barnstedt, L. Conti et al. (+9 more)
Microchannel plates (MCPs) were the driving detector technology for ultraviolet (UV) astronomy over many years, and still today MCP-based detectors are the baseline for several planned UV instruments. The development of advanced MCP detectors is ongoing and pursues the major goals of maximizing sensitivity, resolution, and lifetime, while at the same time decreasing weight, volume, and power consumption. Development efforts for an MCP-based detector system for the UV are running at IAAT at the University of Tübingen. In this publication, we present our latest results towards coating aluminum gallium nitride (AlGaN) photocathodes directly on MCPs, to improve
quantum detection efficiency in the far- and extreme-UV. Furthermore, we report on the implementation of a non-iterative centroiding
algorithm for our coplanar cross-strip anode directly in an FPGA.
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All authors S. Diebold, J. Barnstedt, L. Conti, H.R. Elsener, L. Hanke, M. Höltzli, C. Kalkuhl, D. Rau, D. Schaadt, T. Schanz, B. Stelzer, K. Werner
Astrophysics of Galaxies
Velocity dispersion functions of pressure-supported galaxies in EAGLE simulations with varying active galactic nucleus feedback
Jungwon Choi and Jubee Sohn
We investigate the
stellar velocity dispersion functions (VDFs) of pressure-supported
galaxies in the EAGLE cosmological simulations. The central
stellar velocity dispersion is one of the fundamental dynamical tracers of the total mass of
galaxy subhalos, alongside luminosity and
stellar mass. Because it reflects the gravitational potential, the
stellar velocity dispersion is expected to be relatively insensitive to feedback from Active
Galactic Nuclei (AGN), a critical process that regulates the connection between other
galaxy observables and subhalo mass. To examine the impact of AGN feedback, we analyze the VDFs from five EAGLE simulation runs, each adopting a different AGN feedback model: one "standard", two "enhanced", one "reduced", and one with no AGN feedback. We compute the
stellar velocity dispersions of pressure-supported
galaxies using member
stellar particles, mimicking fiber spectroscopy. The VDFs from the standard and enhanced AGN feedback models show little difference. However, contrary to our initial expectation that the VDF shape would be largely insensitive to AGN feedback, the simulations with reduced and no AGN feedback show a significant excess of high velocity dispersion
galaxies ($\sigma_{*}$ > 200 km s$^{-1}$) and a deficit of low dispersion
galaxies (100 < $\sigma_{*}$ (km s$^{-1}$) < 200), compared to those with standard or enhanced AGN feedback. The presence of high velocity dispersion
galaxies in the no-AGN model arises from enhanced central
star formation, due to the absence of AGN-driven gas heating or expulsion. Our results demonstrate that the shape of the theoretical VDF is sensitive to the strength of AGN feedback. These predictions offer a theoretical
benchmark for future observational studies of the
galaxy velocity dispersion function using large-scale spectroscopic surveys.
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