High Energy Astrophysical Phenomena
Radio Study of Vela X Cocoon
Yihan Liu, Yu Zhang, C.-Y. Ng et al. (+3 more)
The
evolution of
pulsar Wind Nebulae (PWNe) influences how high energy particles in the vicinity are generated and transport. The Vela PWN (only $\sim300$\,pc away), provides a rather rare case between young and well-evolved systems. We therefore performed new 6 and 16\,cm high-resolution observations of the Vela X Cocoon region with the Australia
Telescope Compact Array (ATCA). The observations reveal a complex region with a $\sim0.5^\circ$ major curved filament extending to far south from the
pulsar, as well as other intersecting filaments and wisps. Our spectral analysis hints its connection with the PWN. Our results also found strongly linearly polarized emission, ordered and tangential $B$-field to the filaments. We find the rotation measure (RM) and polarization fraction (PF) along the filament are anti-correlated with the total intensity. We develop a simple 3D model of a spiral filament to explain these, while the PF distribution requires external interpretations such as interaction with the reverse shock. Comparison with archival data suggests that large scale features like the major filament are generally stable and large motions near the X-ray filament, all these confirm the distinction between
radio and X-ray features.
Read the full abstract ▾
All authors Yihan Liu, Yu Zhang, C.-Y. Ng, Zijian Qiu, Sujie Lin, Lili Yang
Solar and Stellar Astrophysics
Photometric Modulations on Intermediate Timescales in the Symbiotic Binaries
Melis Yard{\i}mc{\i}, Samet Ok and Belinda Kalomeni
We present a multi-band study of three symbiotic binaries using combined ground- and space-based monitoring that spans up to 14 years. These
datasets enable a systematic investigation of variability on intermediate timescales (tens of days) and the detection of shorter-period signals. All systems display coherent photometric modulations that are distinct from the orbital cycles. In AX Per, a dominant 75-day signal and its 37-day harmonic are identified, which we interpret as pulsations of the cool
giant. CI Cyg exhibits a stable modulation between 70 and 74 days, which likely arises from a combination of pulsation and circumstellar or disk-related variability. For Z And, we confirm a persistent modulation between 55 and 60 days, consistent with semiregular pulsations of the cool component. Additionally, space-based data reveal further short-period variability, including coherent signals at 26.7 and 66.6 minutes in Z And and CI Cyg, respectively, and a quasi-periodic modulation near 0.95 days in AX Per. These detections suggest the presence of rapid activity driven by
accretion or rotation, superposed on the intermediate timescale behavior. Our results show that the observed variability in these symbiotic binaries reflects the combined effects of cool
giant pulsation, circumstellar or disk activity, and possible rotation of the hot component. The multi-timescale behavior revealed here offers new constraints on mass transfer and activity cycles in interacting binaries.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Systematic errors in spectral measurements with the Tenerife Microwave Spectrometer
A. M. Arriero-Lopez, J. A. Rubiño-Martín, F. Cuttaia et al. (+2 more)
We present an analytical instrument model of the TMS radiometer, a pseudo-correlation system designed for absolute sky-temperature measurements through a continuous comparison between sky and reference-load signals. The goal of this work is to quantify and understand the impact of instrumental non-idealities that are intrinsic to absolute radiometric measurements. We used a combination of the Jones-
matrix formalism, to describe non-ideal signal mixing effects in the different instrument components, and the Friis formalism, to account for noise-temperature contributions which introduce specific offset terms. The model includes all components from the cryostat entrance window onwards and allows us to propagate realistic losses, return losses, and noise figures through the system. We find that non-ideal mixing effects, such as intensity-to-polarization and sky-to-load leakage, are expected to appear at the percent level, but they could be in principle calibrated out. The total TMS intensity response exhibits a frequency-dependent offset with a band-averaged level of 6.9 K, dominated by the cryostat window, and with smaller contributions from the infrared filter and orthomode transducers. Under the required TMS thermal stability of 1 mK over one hour, the resulting variation in the output signal can reach up to 91.3 mK, which sets the fundamental limit on the absolute sky-temperature accuracy. In contrast, relative spectral measurements across the 10-20 GHz band are stable at the few-microkelvin level, consistent with the instrument target sensitivity of ~ 10 Jy/sr. This work provides a detailed and quantitative assessment of the systematic effects affecting absolute radiometric measurements and establishes a robust framework for the calibration and performance optimization of the TMS instrument.
Read the full abstract ▾
All authors A. M. Arriero-Lopez, J. A. Rubiño-Martín, F. Cuttaia, L. Terenzi, R. Hoyland
Solar and Stellar Astrophysics
Core-envelope coupling of gravito-inertial waves in pre-main-sequence solar-type stars
Sylvain N. Breton, Camilla Pezzotti, Stéphane Mathis et al. (+5 more)
After the recent detection of
solar equatorial Rossby waves, a renewed interest has been brought to the study of gravito-inertial waves propagating in the convective envelope of
solar-type
stars. In particular, the ability that some of these envelope gravito-inertial modes have to couple with the ones trapped in the radiative interior might open new windows to probe the deep-layer dynamics of
solar-type
stars. The possibility for such a coupling to occur is particularly favoured in pre-main sequence (PMS)
solar-type
stars. Indeed, due to the contraction of the protostellar object, they are able to reach large rotation frequencies before
nuclear reactions are ignited and
magnetic braking becomes the driving mechanism for their rotational
evolution. In this work, we therefore study the coupling between the envelope inertial waves and the radiative interior g modes in PMS
stars, focusing on the case of prograde dipolar modes. We consider the case of 0.5 Msun and 1 Msun PMS models, each with three different scenarios of rotational
evolution. We show that, for
stars that have formed with a sufficient amount of angular momentum, this coupling can occur in frequency ranges that are accessible to space-borne photometry, creating inertial dips in the period spacing pattern. With an asymptotic analysis we characterise the shape of these inertial dips to show that they depend on rotation and on the stiffness of the convective-radiative interface.
Read the full abstract ▾
All authors Sylvain N. Breton, Camilla Pezzotti, Stéphane Mathis, Lisa Bugnet, Maria Pia Di Mauro, Johannes Joergensen, Konstanze Zwintz, Antonino F. Lanza
Cosmology and Nongalactic Astrophysics
Halo Occupation Distribution estimation performance for LSST data
P. Cataldi, V. Cristiani, F. Rodriguez et al. (+4 more)
Upcoming imaging surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), will enable high signal-to-noise measurements of
galaxy clustering. The
halo occupation distribution (HOD) is a widely used framework to describe the connection between
galaxies and dark matter
haloes, playing a key role in evaluating models of
galaxy formation and constraining cosmological parameters. Consequently, developing robust methods for estimating this statistic is crucial to fully exploit data from current and future
galaxy surveys. The main goal of this project is to extend a background subtraction method to estimate the HOD with more photometry-based information in preparation for the clustering analysis of the upcoming LSST data and to enable the study of the HOD with significantly improved statistical power. We evaluate the performance of the method using a mock
galaxy redshift survey constructed from the cosmoDC2 catalogue. We implement an extension of the background subtraction technique to utilize information from photometric
galaxy surveys. To identify the centres of
galaxy groups, we implement an iterative centroiding approach (Central
Galaxy Finder). We evaluate the impact of each step in our pipeline, including group size estimation from luminosity and purity, and completeness on group identification, along with the influence of observational systematics such as the use of photometric
redshifts and
halo mass uncertainties. We demonstrate the validity of the proposed method using a mock
galaxy catalogue, recovering the HOD from cosmoDC2 over the absolute magnitude range $M_r = -20.0$ to $-17.0$ and
halo masses up to $10^{15}\, \mathrm{M_\odot}$. We present key performance metrics to quantify the precision and reliability of the group finder and the resulting HOD measurements.
Read the full abstract ▾
All authors P. Cataldi, V. Cristiani, F. Rodriguez, A. Taverna, M.C. Artale, B. Levine, the LSST Dark Energy Science Collaboration
Cosmology and Nongalactic Astrophysics
Cancellation of loop corrections to soft scalar power spectrum
Yohei Ema, Muzi Hong, Ryusuke Jinno et al. (+1 more)
We prove the absence of scale-invariant one-loop corrections to the superhorizon
curvature perturbations from small-scale (potentially enhanced) scalar perturbations in a general inflationary setup, including the transient ultra-slow-roll scenario. We demonstrate this by analyzing the
symmetry structure of an in-in effective field theory for the soft
curvature perturbations, and by explicitly performing one-loop calculations, integrating out hard modes in the soft limit of external momenta. The dilatation
symmetry, respected by a counter term necessary for the tadpole cancellation, guarantees the cancellation of scale-invariant corrections.
Read the full abstract ▾
All authors Yohei Ema, Muzi Hong, Ryusuke Jinno, Kyohei Mukaida
Astrophysics of Galaxies
Large scale mapping of [CI] and the [CI]-to-CO transition in $\rho$ Ophiuchus molecular cloud
Jifeng Xia, Ningyu Tang, Thomas G. Bisbas et al. (+10 more)
Atomic carbon ([CI]) is a key species in the carbon chemistry of the interstellar medium (ISM). Using the Submillimeter Wave Astronomy Satellite (SWAS), we conducted a [CI]($^3$P$_1$–$^3$P$_0$) 492 GHz survey covering approximately 4 deg$^2$ of the L1688 and L1689 regions in the $\rho$ Oph molecular cloud, achieving a spatial resolution of 4.25$\hbox{$^{\prime}$}$. The derived [CI] column densities, N([CI]), range from 4.85 $\times$ 10$^{14}$ cm$^{-2}$ to 6.29 $\times$ 10$^{17}$ cm$^{-2}$, corresponding to an abundance ratio N([CI])/N($H_2$) of 2.24$\times$ 10$^{-7}$ to 2.39$\times$ 10$^{-4}$, with a median value of 1.8$\times$ 10$^{-5}$. Combining observations with photodissociation region (PDR) modeling, we find that [CI] abundance varies less than CO in regions with UV intensity G$_0$ $> 16$ and N(H$_2$) $<$ 4.6 $\times$ 10$^{21}$ cm$^{-2}$, suggesting [CI] is a more reliable tracer of molecular hydrogen in low-density, high-radiation environments where the [CI]-to-CO transition occurs. Utilizing [CI] as direct H$_2$ tracer, the CO-dark gas fraction is estimated to be 0.43 , meaning that 43% of the total cloud mass will be missed by conventional calculation based on CO observations but can be calibrated by [CI] emission. The [CI] line widths are systematically broader than those of $^{13}$CO, possibly due to contributions from atomic carbon. These findings provide key insights into
Galactic [CI] emission and the carbon cycle
evolution in the interstellar medium. Future high-sensitivity [CI] ($^3$P$_1$–$^3$P$_0$) surveys with the Chinese Survey Space
Telescope (CSST) will significantly advance our understanding of the carbon cycle
evolution.
Read the full abstract ▾
All authors Jifeng Xia, Ningyu Tang, Thomas G. Bisbas, Chen Wang, Gan Luo, Sihan Jiao, Xin Lv, Xuejian Jiang, Donghui Quan, Jinzeng Li, Paul F. Goldsmith, Gary A. Fuller, Di Li
Cosmology and Nongalactic Astrophysics
Current and future constraints on the expansion history of the GREA model
Irene Graziotti, Chiara De Leo and Matteo Martinelli
In this work, we investigate the General Relativistic Entropic Acceleration (GREA) framework, in which late-time acceleration emerges from
entropy production associated with the cosmological horizon, and compare its performance with the standard $\Lambda$CDM description of the Universe. We first confront GREA with current background observations, including
baryon acoustic oscillations, type Ia
supernovae, compressed CMB information, and
cosmic chronometers, with particular emphasis on the
geometric horizon parameter $\sqrt{-k}\eta_0$. We then introduce a phenomenological extension of the theory by allowing for an additional dark energy component, $\Omega_{de}$, enabling the recovery of a $\Lambda$CDM-like expansion history as a limiting case. We perform a
Bayesian parameter inference and model comparison analysis using both current data and mock
datasets representative of future surveys, including SKAO, LSST, and ET. While current data statistically prefer $\Lambda$CDM when compressed CMB information is included, GREA remains competitive for low-
redshift combinations. Forecasts indicate that gravitational wave standard sirens are expected to enhance the ability to discriminate between entropic-driven and dark-energy-driven expansion scenarios, and to identify the underlying cosmological model favored by the data.
Read the full abstract ▾
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Hadronic description of nuclear matter and neutron star properties
Yao Ma, Yong-Liang Ma and Jia-Ying Xiong
The composition of the
neutron star is one of the most fundamental and long-standing problems in
nuclear- and astro-physics. The known properties of
nuclear matter, together with the astronomical observations, impose the stringent and interconnected constraints on the theoretical descriptions. In this work, by using the most general
quantum hadrodynamics model including $\sigma, \omega, \rho$ and $a_0$ in addition to nucleons, and performing a
Bayesian joint analysis of experimental
nuclear matter data, the heavy-ion flow pressure, and astrophysical observations including the mass-radius inferences of PSR J0740+6620, PSR J0437$-$4715, PSR J0614$-$3329 and HESS J1731$-$347 and the
tidal posterior of GW170817, we point out that the
nuclear matter made of only
hadrons can provide a unified description of
nuclear matter properties and astrophysical observations.In addition, we find that the speed of sound in the GQHD develops a non-monotonic, peak-like structure which is absent in the Walecka-type models TM1, NL3 and FSU-$\delta6.7$. This soft-to-stiff transition, accompanied by a pronounced softening of the
symmetry energy, results in small size intermediate mass
neutron stars, $R_{1.4}\simeq (11.1-11.4)$~km, together with the maximum mass $(2.2-2.3)M_\odot$, and, to our knowledge, has not been found before in the Walecka-type relativistic mean-field models. What we find here indicate that the sequential measurement of
neutron star mass and radius by the next generation facilities, especially that of the intermediate mass
neutron stars, is crucial for distinguishing the pure nucleonic
stars from the hybrid ones.
Read the full abstract ▾
Astrophysics of Galaxies
A New Identification Method and Sample of Counter-Rotating Disk Galaxies in SDSS-IV MaNGA DR17
Maxwell Piper and Alison Crocker
Counter-Rotating Disk (CRD)
galaxies have two co-spatial
stellar disks rotating in opposite directions, and provide a rare opportunity to study external gas
accretion and dynamical assembly processes. In the 16th data release of the Mapping Nearby
Galaxies at Apache Point Observatory (MaNGA) survey, only 64 CRDs were visually identified. Using this as a training sample, we developed an automated pre-selection method that reduces the number of
galaxies requiring visual inspection by removing systems unlikely to host counter-rotation. Applying this method to MaNGA Data Release 17, we identified 126 confirmed CRDs and an additional 143 candidate
galaxies, more than doubling the MaNGA CRD sample. With this extended sample, we analyzed their Baldwin, Phillips, and Terlevich (BPT) emission-line diagrams and compared them with a matched control sample of early-type
galaxies (ETG). We found no statistically significant difference in photoionization sources between CRDs and the ETG control sample, indicating emission-line diagnostics cannot solely be used to identify counter-rotating disks, nor do they correspond to a distinct present-day photoionization signature. Our method facilitates efficient discovery of CRDs in large spectroscopic surveys, enabling stronger statistical studies of their formation and
evolution.
Read the full abstract ▾
Astrophysics of Galaxies
B-fields And dust in interstelLar fiLAments using Dust POLarization (BALLAD-POL): VI. Grain alignment mechanisms in the massive quiescent filament G16.96+0.27 using dust polarization observations from JCMT/POL-2
Saikhom Pravash, Thiem Hoang, Archana Soam et al. (+5 more)
Dust polarization induced by aligned non-spherical grains acts as an important tool to trace the
magnetic field (B-field) morphologies and strengths in molecular clouds and constrain grain properties and their
alignment mechanisms. The widely accepted grain
alignment theory is the
alignment induced by RAdiative Torques (RATs). In this work, we investigate grain
alignment mechanisms in a massive, quiescent and filamentary Infrared Dark Cloud G16.96+0.27 using thermal
dust polarization observation with JCMT/POL-2 at 850 $\mu$m. We observe the so-called phenomenon of polarization hole attributed to the decrease in polarization fraction in denser regions of higher total intensity and gas density. Our study finds that B-field tangling effect is minimal to cause the polarization hole, and the dominant factor is the reduction in grain
alignment efficiency in denser regions, consistent with RAT mechanism. To test RAT theory, we calculate various quantities describing grain
alignment, including minimum size of aligned grains,
magnetic and
magnetic relaxation parameter, and show that RAT mechanism can explain observational data. Our study also reveals evidence for magnetically-enhanced RAT (M-RAT) mechanism required to explain the observed high polarization fractions of above 10 % in the outer regions of the filament. Finally, we perform detailed modeling of thermal
dust polarization using $\mathrm{DustPOL\_py}$ based on M-RAT theory and find that the modeling could successfully reproduce the observational data when maximum grain size is around 0.45 $\mu$m accompanied by an increase in grain axial ratio, along with the consideration of variations in the
magnetic field's inclination angle with the line of sight.
Read the full abstract ▾
All authors Saikhom Pravash, Thiem Hoang, Archana Soam, Qi-Lao Gu, Tie Liu, Pham Ngoc Diep, Le Ngoc Tram, Nguyen Bich Ngoc
Solar and Stellar Astrophysics
A data-driven estimate of the protosolar helium mass fraction
G. Buldgen, M. Kunitomo, A. Noels et al. (+3 more)
The protosolar helium mass-fraction is a key ingredient of
solar, planetary models and enrichment laws. However, the assumed values often rely on simplified descriptions of the transport of chemicals in
solar models. They are also based on the inferred helium mass fraction in the
solar convective envelope, which is itself sensitive to uncertainties in the
solar equation of state. We update the reference protosolar helium abundance by including the effects of macroscopic mixing at the base of the convective zone and more recent determinations of the helium mass fraction in the convective envelope. We combine results from our inversions to spectroscopic abundances, as well as literature values to provide a robust interval of the current helium mass fraction in the convective zone. We combine this measurement to models including light element depletion to provide an udpated protosolar helium abundance. We show that macroscopic mixing at the base of the envelope is key to infer protosolar helium. We find a revised interval of
primordial helium mass fraction of 0.27575 +- 0.00315 slightly lower than previous estimates when combining our latest estimate of surface helium mass fraction and spectroscopic abundances. We find that the effects of macroscopic mixing are partially compensated by an increase in the inferred
solar helium mass fraction in recent studies. We also derive more precise estimates based on various reference works in the litterature. Using the usual surface helium mass fraction, the
primordial helium mass fraction drops to 0.2669 +- 0.00415 due to the inclusion of macroscopic mixing. The dominant source of uncertainty is found the surface helium abundance inferred from helioseismic constraints and more specifically, the impact on the equation of state of the
solar material on this inference result.
Read the full abstract ▾
All authors G. Buldgen, M. Kunitomo, A. Noels, T. Guillot, R. Scuflaire, N. Grevesse
Astrophysics of Galaxies
A z$\sim$1 galactic-scale outflow transversally mapped to $\sim$50 kpc through gravitational-arc tomography
J. A. Hernández-Guajardo, L. F. Barrientos, S. López et al. (+12 more)
We report spatially resolved measurements of cool gas traced by Mg II and Fe II absorption in the circumgalactic medium (CGM) of a
star-forming
galaxy at $z\sim1$ (G1). The fortuitous
alignment of a background gravitational arc at z$\sim$2.4 provides seven closely spaced ($\sim$6 kpc) transverse sightlines along the minor axis of G1, probing its CGM out to $\sim$50 kpc. This geometry allows us to detect a
galactic-scale
outflow simultaneously in down-the-barrel and transverse directions, where blue-shifted Mg II absorption is detected along both types of sightlines, revealing a large-scale, collimated wind. We measure blue-shifted line-of-sight velocities of $v_{\mathrm{los}}$ $\sim$ 62 - 239 km s$^{-1}$ and line-of-sight velocity dispersions $\sigma_{\mathrm{los}}$ $\sim$ 53 - 133 km s$^{-1}$, suggesting a structure dominated by bulk motion. De-projection of $v_{\mathrm{los}}$ along the minor axis indicates that the
outflow material barely approaches the escape velocity and is likely to be gravitationally bound to G1. We constrain an
outflow opening angle $\theta_c\sim$ 18$^\circ$ - 25$^\circ$, and a mass
outflow rate of $ \dot{M}_{\mathrm{out}}$ $\gtrsim$ 0.06 $M_\odot$ yr$^{-1}$, corresponding to a mass loading factor $\eta$ $\gtrsim$ 0.004, estimated within $\sim$10 - 50 kpc ($\sim$ 0.05 - 0.3 $R_\text{vir}$) of the
galaxy centre. Our measurements, combined with previous arc
tomography data along the major axis, indicate that normalizing impact parameters by
galaxy B-band luminosity substantially reduces scatter in the established anti-correlation between Mg II equivalent width and impact parameter, while also diminishing possible excess of Mg II equivalent width towards the minor axis.
Read the full abstract ▾
All authors J. A. Hernández-Guajardo, L. F. Barrientos, S. López, E. J. Johnston, C. Ledoux, N. Tejos, A. Afruni, M. Solimano, E. Jullo, H. Cortés-Muñoz, P. Noterdaeme, J. González-López, A. Ormazábal, F. Muñoz-Olivares, T. A. M. Berg
High Energy Astrophysical Phenomena
Estimating the peak energy of Swift gamma-ray bursts using supervised machine learning
Wan-Peng Sun, Si-Yuan Zhu, Da-Ling Ma et al. (+1 more)
Gamma-ray bursts (GRBs) are among the most energetic explosive phenomena in the Universe, and their peak energy ($E_{\rm p}$) is a key physical quantity for understanding the
prompt emission mechanism. However, due to the limited energy coverage of the Swift satellite, a large fraction of Swift GRBs lack reliable peak energy measurements. Therefore, developing an accurate and efficient method for estimating $E_{\rm p}$ is of great importance. In this work, we propose a method based on the SuperLearner framework that integrates multiple supervised machine learning
algorithms to estimate the $E_{\rm p}$ of Swift/BAT GRBs. We used the Swift/BAT observational data from December 2004 to September 2022 as training features, and adopted the peak energies of 516 GRBs jointly detected by Swift and either
Fermi/GBM or Konus-Wind as training labels. After training and testing multiple supervised models, the final SuperLearner ensemble yields a more robust and reliable predictive model. In 100 iterations of five-fold cross-validation, the estimated $E'_{\rm p}$ values show a tight correlation with the observed $E_{\rm p}$, with an average Pearson correlation coefficient of $r = 0.72$. Compared with previous
Bayesian estimates, our model provides estimations that are likely closer to the true values. Based on the trained model, we further estimated the peak energies of 650 Swift GRBs, significantly increasing the number of GRBs with estimated peak energies and providing new statistical support for constraining GRB emission mechanisms and energy origins.
Read the full abstract ▾
All authors Wan-Peng Sun, Si-Yuan Zhu, Da-Ling Ma, Fu-Wen Zhang
Solar and Stellar Astrophysics
Observational insights into Sr I 4607 Å\ scattering polarization with DKIST/ViSP
Franziska Zeuner, Ernest Alsina Ballester, Luca Belluzzi et al. (+4 more)
Scattering polarization signals in the Sr I 4607 Å\ spectral line are among the strongest originating from the
solar photosphere, offering a powerful diagnostic of tangled
magnetic fields in the 3–300 G range via the Hanle effect. However, measuring them with sub-arcsec resolution remains a significant challenge. We analyze spatially resolved quiet-Sun observations of these signals performed with the Visible Spectropolarimeter (ViSP) at the Daniel K. Inouye
Solar Telescope (DKIST) and identify its current observational limits. We present high-resolution, high-precision spectropolarimetric observations in a spectral window including the Sr I 4607 Å\ line at various limb distances. We apply consistent instrumental corrections across all spectral lines, enabling the adjacent lines to serve as reliable references. At a limb distance of $\mu = 0.74$, the signal-to-noise ratio is low but sufficient in the total linear polarization map to directly reveal sub-arcsec structures in the Sr I line for the first time, which can be attributed to scattering polarization. Disk-center measurements are still dominated by noise related to the current limitations of the observational setup. By combining high spatio-temporal and spectral resolution with exceptional polarimetric precision, DKIST enables measurements of
solar photospheric scattering polarization at fine scales. However, current signal-to-noise limitations still hinder direct detection of disk-center scattering polarization and must be addressed before further progress can be made.
Read the full abstract ▾
All authors Franziska Zeuner, Ernest Alsina Ballester, Luca Belluzzi, Roberto Casini, David M. Harrington, Tanausú del Pino Alemán, Javier Trujillo Bueno
Astrophysics of Galaxies
Triaxial Schwarzschild Models of Brightest Cluster Galaxies with Long-Slit LBT Data
Stefano de Nicola, Roberto P. Saglia, Jens Thomas et al. (+3 more)
We present new long-slit
stellar kinematics for a sample of 21 Brightest Cluster
Galaxies (BCGs) and triaxial Schwarzschild models for 16 of these objects using our orbit modelling code SMART. The new kinematics obtained with the Large Binocular
Telescope (LBT) is complemented with high-resolution photometry from HST or new AO-assisted ground-based observations also obtained at LBT and combined with wide-field imaging from the Wendelstein Observatory. These data enable robust modeling from the innermost regions - where the Supermassive Black Hole dominates the potential - to larger radii, where
stars and dark matter (DM) are the primary mass contributors. As already discussed in a companion paper, we discovered 8 Ultramassive Black Holes (UMBHs, with mass $> 10^{10}$ M$_\odot$) in this BCG sample, more than doubling the number of
galaxies with dynamically detected UMBHs. We show that the DM
halos display a wide variety of geometries. Purely kinematical results include low central velocity dispersion with increasing profiles towards the outskirts, and the discovery of one Kinematically Decoupled Core.
Read the full abstract ▾
All authors Stefano de Nicola, Roberto P. Saglia, Jens Thomas, Jan Snigula, Matthias Kluge, Ralf Bender
Earth and Planetary Astrophysics
A universal brown dwarf desert formed between planets and stars
Kaiming Cui, Guang-Yao Xiao, Fabo Feng et al. (+10 more)
Giant planets and brown
dwarfs play a crucial role in
star and
planet formation, as they are situated at the boundary between
planets and
stars with uncertain formation mechanisms. Previous observational searches for the formation boundary were hampered by the lack of large unified samples of wide-orbit
giant planets and substellar companions. A combined analysis of radial velocity and astrometry mitigates this problem and has significantly enlarged the sample. Here we present a rigorous statistical analysis of the sample of 55
giant planets, brown
dwarfs and low-mass
stellar companions orbiting FGK
stars. We quantitatively analyze the occurrence rates of brown
dwarfs and identify a distinct brown
dwarf desert at approximately $30\,M_\mathrm{J}$, with no evidence of disappearance up to 20 au. Unlike previous studies that predicted a declining
planet occurrence rate beyond the water-ice line, we identify a new population of
giant planets and low-mass brown
dwarfs in this region. The
metallicity and eccentricity trends in our sample suggest that these are the consequences of two different formation scenarios. Our combined population synthesis model successfully accounts for the observed brown
dwarf desert, supporting the dual formation hypothesis.
Read the full abstract ▾
All authors Kaiming Cui, Guang-Yao Xiao, Fabo Feng, Beibei Liu, Sergei Nayakshin, Cassandra Hall, Kangrou Guo, Dong Lai, Masahiro Ogihara, Yicheng Rui, Alan P. Boss, R. Paul Butler, Yifan Xuan
Earth and Planetary Astrophysics
Quantification of Tides in Giant Planets from Observations
Valéry Lainey, Marco Zannoni, Vincent Robert et al. (+1 more)
Quantifying
tidal effects on
giant planets has recently made significant advances, thanks in particular to the Cassini space probe. During its thirteen-year orbit around Saturn, numerous measurements from different instruments made it possible to characterize fundamental parameters such as Saturnś Love number $k_2$ and quality factor $Q$ at different frequencies. In this article, we summarize the various measurements and methods that have allowed to arrive at such a result, as well as the extrapolations that can be deduced for other systems. More generally, the state of the art concerning the four
giant planets of the
Solar System is presented, as well as the case of
exoplanets.
Read the full abstract ▾
All authors Valéry Lainey, Marco Zannoni, Vincent Robert, Tristan Guillot
Cosmology and Nongalactic Astrophysics
Testing the isothermal Jeans model for self-interacting dark matter halos in the collapse phase
Shubo Li, Moritz S. Fischer, Zixiang Jia et al. (+3 more)
We
benchmark the semi-analytical isothermal Jeans model against a high-resolution isolated N-body simulation that follows a self-interacting dark matter (SIDM)
halo into deep core collapse. The model accurately reproduces the density
evolution through much of the collapse phase, although it does not capture the sharp rise in central velocity dispersion during collapse. When applied to strong gravitational
lensing observables, such as the projected mass and logarithmic density slope of SIDM
halos, the Jeans model tracks the simulated
evolution more closely than the parametric approach in the deep collapse regime. Our results demonstrate that the isothermal Jeans model provides a reliable and computationally efficient description of SIDM
halo evolution.
Read the full abstract ▾
All authors Shubo Li, Moritz S. Fischer, Zixiang Jia, Fangzhou Jiang, Ran Li, Hai-Bo Yu
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
ImpCresst – A versatile simulation tool focusing on solid-state detectors at keV energies
G. Angloher, S. Banik, A. Bento et al. (+57 more)
We present ImpCresst, a Geant4-based Monte Carlo tool to simulate backgrounds from natural and cosmogenic radionuclides, and calibration signals in solid-state detectors and their response to it. It is tuned for a fast-evolving and heterogeneous detector environment with a focus on physics at the keV range. This tool was originally developed and validated by the CRESST collaboration; however, its flexibility and configurability make it suitable for other experiments with similar requirements. Key features of ImpCresst include the dynamic geometry implementation directly from CAD files, ROOT-based data persistency of the whole event
topology and automatic metadata annotation for data provenance, and interfaces to various particle generators, particularly for radiogenic and cosmogenic radionuclides. It includes also a newly developed particle generator for radioactive bulk and surface contaminations which is completely independent of any user defined confinement volumes. The auxiliary tool CresstDS applies detector-specific energy and time resolution based on a user-provided data set of empirical parameterization. We discuss also how to manage an ImpCresst based workflow in an HPC environment based on Apptainer and nextflow.
Read the full abstract ▾
All authors G. Angloher, S. Banik, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Burmeister, L. Canonica, F. Casadei, E. Cipelli, S. Di Lorenzo, J. Dohm, F. Dominsky, A. Erb, E. Fascione, F. von Feilitzsch, S. Fichtinger, D. Fuchs, A. Fuss, V.M. Ghete, P. Gorla, P.V. Guillaumon, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva, H. Kluck, H. Kraus, B. von Krosigk, A. Langenkämper, M. Mancuso, B. Mauri, V. Mokina, C. Moore, P. Murali, M. Olmi, T. Ortmann, C. Pagliarone, L. Pattavina, F. Petricca, W. Potzel, P. Povinec, F. Pröbst, F. Pucci, F. Reindl, J. Rothe, K. Schäffner, J. Schieck, S. Schönert, C. Schwertner, M. Stahlberg, L. Stodolsky, C. Strandhagen, R. Strauss, F. Toschi, I. Usherov, D. Valdenaire, M. Zanirato, V. Zema
Earth and Planetary Astrophysics
KMT-2025-BLG-1314 and KMT-2025-BLG-1392: two microlensing planetary/brown-dwarf candidates analyzed with differentiable code
Haibin Ren, Weicheng Zang, Wei Zhu et al. (+20 more)
Analysis of binary-lens microlensing events typically requires intensive computation because of the
multimodal and complex posterior distributions. With the recent development of the JAX-based differentiable binary-
lensing modeling package microlux, we present an analysis of two microlensing events with
planet/brown-
dwarf candidates, KMT-2025-BLG-1314 and KMT-2025-BLG-1392. Both events exhibit the "Close/Wide" degeneracy, and KMT-2025-BLG-1314 suffers from the "
Planet/Binary" degeneracy and a recently recognized "Point/Finite" degeneracy among the planetary solutions. For KMT-2025-BLG-1314, the binary mass ratio is $\log q \sim -3.5$ for the planetary solutions and $\log q > -1.5$ for the binary solutions, while for KMT-2025-BLG-1392, we find $\log q \sim -1.3$. We show that for the analysis of KMT-2025-BLG-1314,
Hamiltonian Monte Carlo (HMC), enabled by microlux, provides robust parameter inference and outperforms traditional Markov chain Monte Carlo (MCMC) methods in the presence of bimodal posteriors.
Read the full abstract ▾
All authors Haibin Ren, Weicheng Zang, Wei Zhu, Yoon-Hyun Ryu, Yuchen Tang, Jiyuan Zhang, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Yossi Shvartzvald, Hongjing Yang, Jennifer C. Yee, Dong-Jin Kim, Chung-Uk Lee, Byeong-Gon Park, Yunyi Tang, Dan Maoz, Shude Mao, Qiyue Qian
Astrophysics of Galaxies
The Galaxy Stellar Mass-SFR-Size Relation in EAGLE, TNG100, and Observations
Jiani Chu, Dandan Xu, Enci Wang et al. (+1 more)
Stellar mass, size, and
star formation rate (SFR) are fundamental properties that encode the structural and evolutionary states of
galaxies. Observations reveal a mass-SFR-size relation whereby
galaxies become more compact both above and below the ridge of the
star-forming main sequence (SFMS), linking
galaxy structure to
star formation activity. We investigate this relation by comparing
galaxies from two cosmological hydrodynamical simulations, EAGLE and TNG100, with observational samples from SDSS and CANDELS over three
redshift intervals (0 < z < 0.2, 0.5 < z < 1.5, and 1.5 < z < 2.5). Both simulations reproduce the observed trend that
galaxy sizes decrease with increasing offset away from the SFMS. This trend, however, weakens and is not detected in the observational sample at 1.5 < z < 2.5, likely due to increased measurement uncertainties. In contrast, the trend persists in both simulations up to z = 2.5. Across all
redshifts, EAGLE predicts a stronger size dependence on SFMS offset than observed, whereas TNG100 exhibits a weaker dependence. We discuss how this mass-SFR-size relation can be understood in terms of different time variability in
star formation rate across the SFMS.
Read the full abstract ▾
All authors Jiani Chu, Dandan Xu, Enci Wang, Stijn Wuyts
Solar and Stellar Astrophysics
Planet-forming disks and their environment across regions and time from the full NIR census
Antonio Garufi, Christian Ginski, Myriam Benisty et al. (+5 more)
The
evolution of
planet-forming disks and the processes of
planet formation influence each other, and both of them are possibly impacted by the local environment. Extensive high-resolution imagery of disks across space and time is the best tool for determining their
evolution. We compiled a comprehensive list of disk-bearing young
stars with near-IR high-contrast images available. The sample sums up to 268 sources, including 51 targets with no prior publications, which makes this study the largest of its kind and the most extensive release of IR disk images to date. Our census reveals very diverse disk and ambient morphologies. Disks in Lupus are bright, in Chamaeleon are faint, in Corona Australis and Taurus are frequently surrounded by ambient emission. Disks experience an abrupt increase in IR brightness between 2 Myr and 5 Myr. The earliest IR disk cavities around single
stars arise after 2-3 Myr explaining why are young disks faint in the near-IR, and determining which disks can live longer. Well-known, high-longevity disks (>8 Myr) are always bright. Ambient material is detected in more than 20% of young sources but the fraction drops with time. We find a clear correspondence for the presence of ambient material with the
stellar variability, near-IR excess, and mass
accretion rate as well as, in turn, with spirals and shadows in disks. Half of the disks with ambient material show spirals while none of them show rings. We therefore propose that the spirals and the disk warps responsible for shadows are generally induced by late infall from the medium, and that this also affects the
stellar accretion. The emerging picture proves the fundamental role of the environment for the disk
evolution and
planet formation.
Read the full abstract ▾
All authors Antonio Garufi, Christian Ginski, Myriam Benisty, Miguel Vioque, Andrew Winter, Jane Huang, Carlo Felice Manara, Carsten Dominik
Astrophysics of Galaxies
A Unified Explanation for JWST Little Red Dots and High-Redshift Low-Mass Disk-like Galaxies: Prolate Galaxies Viewed End-on vs Side-on
Yingjie Peng
Recent JWST surveys have revealed two puzzling high-
redshift phenomena: (1) an unexpectedly large abundance of flattened, disk-like
galaxies at z > 3, and (2) a rare population of compact, extremely red sources at z ~ 4-9 ("Little Red Dots," LRDs) that often show V-shaped SEDs and very broad Balmer lines. These findings lack a consensus interpretation and have motivated models ranging from dusty starbursts to obscured AGN and more exotic scenarios. We propose that both phenomena are linked by a simple
geometric consequence of a third clue: mounting evidence from structural modeling and axis-ratio statistics indicates that many low-mass
galaxies at z > 3 are intrinsically prolate (cigar-like), not oblate rotation-supported disks. In this picture, a substantial fraction of the flattened, disk-like morphologies reported at z > 3 arise from side-on and intermediate-angle projections of prolate systems, while the rare near end-on views appear extremely compact and high-surface-brightness, and are preferentially reddened by the maximal line-of-sight column, naturally matching key elements of LRD selection. The expected fraction of near end-on systems, $P_{\text{end}} = 1 - \cos(\theta_{\text{max}})$, is ~1-3% for $\theta_{\text{max}}$ ~ 10{\deg}-15{\deg}, consistent with LRD demographics in wide JWST fields. This orientation-based framework does not exclude AGN or starburst activity; rather, it explains LRD rarity as an orientation effect and provides a natural route to the large columns of gas/
dust and scattering depths inferred in recent dense-gas and electron-scattering interpretations of LRD spectra, without fine-tuned new physics. The model makes falsifiable predictions to validate or rule out this
geometric interpretation.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
$\mathcal{H}$-EFTCAMB: A Cobaya-Integrated, Python-Wrapped Extension of EFTCAMB for Covariant Horndeski Gravity
Gen Ye, Shijie Lin, Jiaming Pan et al. (+6 more)
We present $\mathcal{H}\mathtt{-EFTCAMB}$, the official successor to $\mathtt{EFTCAMB}$. The original $\mathtt{EFTCAMB}$ is designed as a consistent and numerically stable implementation of the effective field theory (EFT) of dark energy in the Einstein-Boltzmann code $\mathtt{CAMB}$. On top of this, $\mathcal{H}\mathtt{-EFTCAMB}$ introduces a new Horndeski module that supports computing cosmology for an arbitrary input covariant Horndeski Lagragian. $\mathcal{H}\mathtt{-EFTCAMB}$ supports both mapping the Horndeski theory to an EFT lagrangian to solve in the EFT framework as well as directly solving for the scalar field equations of motion derived from the covariant Lagrangian. The latter approach also works for the cases when the Horndeski field experiences turn-overs, e.g. oscillation, where the EFT approach breaks down. The Horndeski module has been validated by comparing internally with existing models in the original $\mathtt{EFTCAMB}$ and externally with $\mathtt{hi\_class}$. $\mathcal{H}\mathtt{-EFTCAMB}$ features a flexible Python wrapper that is seamlessly integrated into the widely utilized cosmological sampler $\mathtt{Cobaya}$. \heft~is publicly available and serves as a comprehensive tool for testing
gravity against the precision data from current and next-generation surveys.
Read the full abstract ▾
All authors Gen Ye, Shijie Lin, Jiaming Pan, Dani de Boe, Stan Verhoeve, Marco Raveri, Bin Hu, Noemi Frusciante, Alessandra Silvestri
High Energy Astrophysical Phenomena
Episode-wise spectro-polarimetry of GRB 220107A: Testing the hypothesis of evolving radiation mechanisms
Rahul Gupta, Rushikesh Sonawane, Shabnam Iyyani et al. (+17 more)
We investigate the spectro-polarimetric properties of the long-duration GRB~220107A, which exhibited two distinct emission episodes separated by a 40 s quiescent gap, to test whether such multi-episode bursts show evidence for
evolution in their underlying radiation mechanisms. We analyzed
prompt emission data from AstroSat/CZTI,
Fermi/GBM, and Konus-Wind, performing spectro-polarimetric analysis for each emission episode. The time-integrated polarization analysis shows no significant detection (PF$ < 38 \%$, $2\sigma$). Time-resolved analysis reveals clear spectral
evolution between the two episodes, with episode 1 exhibiting a hard low-energy
photon index and episode 2 showing substantial spectral softening ($\alpha \sim -0.72$). Regarding polarization: Episode 1 shows a low polarization upper limit (< 52%), consistent with expectations for photospheric emission dominated by quasi-thermal Comptonization in a
baryon-rich
outflow. Episode 2 also shows overall low polarization (PF$ < 55 \%$, $2\sigma$), though sliding-window analysis yields a marginally elevated signal (PF$= 70 \pm 30\%$, BF = 2.8) between T0+76 to T0+88 s. The robust spectral softening between episodes could arise from sub-photospheric dissipation, optically thin synchrotron radiation in small-scale
magnetic fields, or if the tentative polarization enhancement proves intrinsic, it would favor synchrotron emission in large-scale ordered
magnetic fields. The spectral
evolution of GRB 220107A, combined with our polarimetric constraints, demonstrates the diagnostic potential of time-resolved spectro-polarimetry for constraining GRB
prompt emission physics. We present GRB 220107A as a test case illustrating how future higher sensitivity observations could discriminate between competing emission models for multi-episode bursts. Our results emphasize both the promise and current limitations of
prompt phase polarimetry.
Read the full abstract ▾
All authors Rahul Gupta, Rushikesh Sonawane, Shabnam Iyyani, D. Frederiks, Judith Racusin, Tanmoy Chattopadhayay, A. J. Castro-Tirado, A. F. Valeev, Soumya Gupta, Mayuresh Tembhurnikar, A. Ridnaia, D. Svinkin, S. B. Pandey, Dipankar Bhattacharya, Vidushi Sharma, Varun Bhalerao, G. C. Dewangan, Santosh Vadawale, R. Sánchez-Ramírez, Anastasia Tsvetkova
Instrumentation and Methods for Astrophysics
SPACE-Timers – A Stack-Based Hierarchical Timing System for C++
Geray S. Karademir and Klaus Dolag
SPACE-Timers are a lightweight hierarchical profiling framework for C++ designed for modern high-performance computing (HPC) applications. It uses a stack-based timing model to capture deeply nested execution patterns with minimal overhead, representing runtime behaviour as a tree of timing nodes with precise attribution. The framework provides structured reports with recursive aggregation, detection of unaccounted time, and compact visual summaries of runtime distribution, supporting both quick inspection and detailed analysis. It also includes checkpointing and error detection mechanisms. SPACE-Timers supports multiple profiling backends, including NVTX, ITT, ROCtx, and Omnitrace, and integrates with the MERIC runtime system to enable energy-aware optimisation. Its successful use in OpenGadget3 demonstrates its effectiveness for large-scale scientific applications.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Superfluid Vortex Lines-Magnetic Flux Tubes Interaction and Braking Indices of Pulsars
Erbil Gügercinoğlu
Braking of
pulsars, or the law of their
spin deceleration, is a manifestation of the combination of various processes occurring in the magnetospheres of
neutron stars and their internal structural dynamics. The interaction of superfluid
neutron vortex lines with superconducting
magnetic flux tubes in the
neutron star core plays a significant role in rotational
evolution and
magnetic field
evolution through
spin glitches and
magnetic flux expulsion. In this study, the effect of this interaction on the temporal variation of the braking index of
pulsars is investigated. The variation of the deviation from the $n=3$ value predicted by the generally accepted
magnetic dipole formula with respect to physical parameters such as the
magnetic field and the age of the
neutron star has been elaborated, and applications have been made to
pulsars with reliably measured braking indices.
Read the full abstract ▾
Earth and Planetary Astrophysics
Modelling the long-term impacts of artificial warming on the Martian water cycle and surface ice distribution
Ashwin S. Braude, Edwin S. Kite, Mark I. Richardson et al. (+2 more)
Recent papers by Ansari et al. (2024, Science Advances 10, eadn4650) and Richardson et al. (2025, arXiv eprint 2504.01455) have suggested that global warming of the Martian surface ('terraforming') by 35 K to sustain local habitats above the melting point of water could be achieved through the injection of engineered aerosols into the Martian atmosphere. Using the MarsWRF 3D Global
Climate Model, we investigate how artificial warming of Mars through engineered aerosol release would affect the planetary water cycle and the distribution of the major surface ice reservoirs. Within our model framework, every 20 K of global warming induces a tenfold increase in atmospheric water vapour content due to sublimation of H2O ice from the North Polar Cap. This increases the potency of cloud radiative feedbacks which induces nighttime warming (~5-10 K) at low latitudes, but daytime cooling (up to 40 K) in the winter midlatitudes. Water is transferred from the edge of the North Polar Cap to the South Polar Cap and there is minor destabilisation of shallow northern midlatitude subsurface ice. As a result, seasonal sublimation of H2O ice from the South Pole has an increased impact on the global water cycle. These changes persist on Mars at least decades after loading of the atmosphere with engineered aerosols ceases. Our model is limited by the gaps in our knowledge of present-day Martian weather and
climate, and of the microphysics and radiative properties of candidate warming
agents. Much more data is therefore needed before warming Mars could become feasible.
Read the full abstract ▾
All authors Ashwin S. Braude, Edwin S. Kite, Mark I. Richardson, Alexandre Kling, Michael A. Mischna
Earth and Planetary Astrophysics
The Intrinsic Multiplicity Distribution of Exoplanets Revealed from the Radial Velocity Method. II. Constraints on Giant Planet Multiplicity from Different Surveys
Jiayin Li and Wei Zhu
Compared to the commonly used
planet occurrence rates, the multiplicity distribution of
planets can be more useful in constraining the formation and
evolution pathways of planetary systems. This work follows an earlier work of Zhu (2022) and derive the intrinsic multiplicity distribution of
giant planets (with masses above Saturn mass) from two independent radial velocity (RV) surveys. In particular, we find that $(7.8\pm1.4\%, 2.3\pm1.2\%, 0.5^{+0.8}_{-0.3}\%)$ of Sun-like
stars in the HARPS sample have $(1, 2, 3)$
giant planets within 10\,au, whereas $(7.3\pm2.8\%, 7.2\pm2.3\%, <1.3\%, 1.0^{+1.0}_{-0.6}\%)$ of Sun-like
stars in the California Legacy Survey (CLS) have $(1, 2, 3, 4)$
giant planets within 10\,au. Here we have further cleaned the CLS sample and removed
planet detections that were not discovered in the survey mode. The total fraction of Sun-like
stars with at least one
giant planet within 10\,au from the two samples are $10.6\pm1.2\%$ and $15.8\pm2.1\%$, respectively, and the difference may be accounted for by their different
metallicity distributions. We briefly discuss the theoretical implications of our results. In particular, the inferred
giant planet multiplicity distribution is inconsistent with most of the proposed theoretical models involving
planet–
planet scatterings, which predict too many multi-
giant systems.
Read the full abstract ▾