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Research Trends

Latest preprints in space engineering and astrophysics.

astro-ph.GA

The influence of feedback on the baryonic content of haloes in the COLIBRE simulations

Jonathan J. Davies, Joop Schaye, Filip Huško, Ruby J. Wright, Evgenii Chaikin, Matthieu Schaller, Robert J. McGibbon, Alejandro Benítez-Llambay et al.

We present predictions for the relation between the halo gas mass fraction and halo mass, $f_{\rm gas}^{200}-M_{200}$, from the COLIBRE cosmological simulations of galaxy formation, and explore how the gas content of haloes is influenced by feedback from supernovae and active galactic nuclei (AGN) over time. The $f_{\rm gas}^{200}-M_{200}$ relation in COLIBRE is non-monotonic, with a peak at $M_{200}\sim 10^{11.5-12}$~M$_\odot$. Below this mass, feedback from supernovae efficiently expels gas fr…

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astro-ph.IMastro-ph.COcs.LG

Emulating Cosmic Structure Formation with a Lagrangian Neural Cellular Automaton

Cooper Jacobus, Beatriz Tucci, Oliver Philcox

Field-level inference of cosmological initial conditions from galaxy surveys requires a forward model that is simultaneously accurate in the non-linear regime, computationally efficient, and fully differentiable. Traditional N-body simulations are accurate but computationally prohibitive for iterative inference, while approximate solvers like Lagrangian Perturbation Theory (LPT) fail to capture the knotty halo-forming dynamics of the cosmic web at late times. We introduce the \textit{Lagrangian…

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astro-ph.IMastro-ph.HEgr-qc

Assessing the Impact of Instrumental Requirements on the Scientific Performance of the Einstein Telescope

Ulyana Dupletsa, Francesco Iacovelli, Mikhail Korobko, Valeria Sequino, Alessandro Agapito, Manuel Arca Sedda, Biswajit Banerjee, Nicolò Cibrario et al.

We investigate the relationship between instrumental requirements and the scientific performance of the Einstein Telescope (ET), a third-generation (3G) gravitational-wave (GW) observatory. Different technical design choices result in distinct noise budgets, ultimately shaping the detector's scientific capabilities. To systematically assess and compare their impact, we define a comprehensive set of performance metrics spanning compact binary coalescence (CBC) detection and parameter estimation,…

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astro-ph.GAastro-ph.COhep-ph

Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part I. Comparison to Ultra-faint Dwarf Kinematics

Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi

Ultra-faint dwarf galaxies are critical testing grounds for probing the limits of galaxy formation in the cold dark matter (CDM) paradigm. Employing a semi-analytic cosmological satellite generator that captures the expected CDM halo population, we estimate Milky Way dwarf density profiles through two methods: a kinematic approach using stellar velocity dispersions and a separate method based on dwarf stellar masses. The kinematic approach yields a larger diversity in central dark matter densiti…

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astro-ph.GA

Superdiffusion at the Galactic Centre

Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro et al.

Tracking S-star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via local Fokker-Planck equations, which predict that general relativistic precession halts angular momentum diffusion at the Schwarzschild barrier. Because inverse-square gravitational encounters generate a Holtsmark torque distribution with infinite variance, resonant relaxation operates as a space-fractional process governe…

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astro-ph.EP

An Inclined, Eccentric Planet and an Inner Debris Disk Could Reproduce AU Mic Structure

Arcelia Hermosillo Ruiz, Ruth Murray-Clay, Meredith A. MacGregor, Renata Frelikh

The debris disk orbiting the M star AU Microscopii has a series of large-scale clumps that move away from the star at high velocities above the mid-plane on the southeast side. Two more bright features lie on the northwest side of the disk, localized below the mid-plane and moving toward the star. These clumps are only observed in scattered light indicating that they affect small 0.2$μ$m-sized grains. We present a mechanism for emitting periodic dust clumps by appealing to stellar forces and an…

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astro-ph.COastro-ph.GA

Shear-kSZ: A New Estimator for the Matter-Electron Power Spectrum from kSZ Tomography and Weak Lensing

Boryana Hadzhiyska

We propose a new estimator for the ionized gas--matter power spectrum, which correlates the kinematic Sunyaev--Zel'dovich (kSZ) field with the line-of-sight velocity field and the weak-lensing convergence map. Analogously to the standard stacked kSZ estimator, this estimator factorizes into a calibratable velocity kernel multiplying the matter--electron cross-power spectrum, $P_{me}(k)$. Because the estimator accesses $P_{me}(k)$ for the full matter distribution rather than around a specific bia…

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astro-ph.GA

J-ATLAS: Javalambre Andromeda and Triangulum Legacy Astrophysical Survey

Borja Anguiano, Andres del Pino

The outskirts of nearby galaxies preserve long-lived signatures of hierarchical assembly and provide a fossil record of galaxy formation. J-ATLAS, the Javalambre Andromeda and Triangulum Legacy Astrophysical Survey, is a proposed wide-field optical photospectroscopic survey of the M31--M33 system with JST/T250 and JPCam. Using the dense J-PAS filter system, it will deliver homogeneous low-resolution optical SEDs for resolved stars, compact stellar systems, emission-line sources, and background o…

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astro-ph.IM

High-speed, low-noise, multi-megapixel CCDs for next generation X-ray observatories

Haley R. Stueber, Tanmoy Chattopadhyay, Peter Orel, Steven W. Allen, Marshall W. Bautz, Michael Cooper, Kevan Donlon, Catherine E. Grant et al.

Next generation X-ray observatories require fast, low-noise, low-power, multi-megapixel imaging spectrometers. To meet these demands, the X-ray Astronomy and Observational Cosmology (XOC) Group at Stanford, in partnership with the MIT Kavli Institute and MIT Lincoln Laboratory (MIT-LL), is developing multi-channel X-ray charge-coupled devices (CCDs) and fast readout architectures. We report the energy resolution and noise performance achieved with a full-scale (1440x1440-pixel), 16-channel, fron…

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astro-ph.HE

Braking indices as probes of r-mode spin-down in young pulsars

Shahram Abbassi, Armin Memarian, Evelyn Sophia Guest, S. R. Valluri

We present a timing-based framework for interpreting braking-index measurements in young pulsars using a four-channel spin-down model that includes particle-wind, magnetic-dipole, mass-quadrupole, and current-quadrupole torques. The observed braking index is a torque-weighted average of the channel exponents, enabling equation-of-state-independent constraints on the torque fraction of a possible r-mode-like current-quadrupole component from timing data alone. For positive, slowly varying secular…

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astro-ph.HEgr-qc

Universality of dual mass-scaled fundamental modes in two-fluid neutron stars with mirror dark matter

Hajime Sotani, Ankit Kumar

Universal relations provide a particularly useful way to extract physical information from neutron star observables in the presence of various uncertainties by reducing the dependence on uncertain model parameters and microphysical inputs. In this study, we examine the oscillation frequencies of mirror dark matter admixed neutron stars using a two-fluid description, where the outer and inner fluids give rise to two distinct fundamental frequencies. We confirm that the universal relation between…

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astro-ph.GAastro-ph.CO

Constraining the shape of dark matter haloes using only starlight II. Tests of the technique with objects of known gravitational potential

Jorge Sanchez Almeida, Angel R. Plastino, Sergio Guerra Arencibia, Nitya Kallivayalil, Jack T. Warfield

Under the collisionless cold dark matter (CDM) paradigm, galaxies with stellar masses below 10**(5-6) Msun are expected to preserve primordial cuspy dark matter (DM) profiles. Because baryonic feedback should be too weak to transform cusps into cores at these masses, such galaxies provide especially sensitive tests of DM physics. If cores are observed in these systems, they could indicate departures from CDM. To address this problem, Sanchez Almeida et al. (2025) introduced the Eddington Inversi…

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astro-ph.IMastro-ph.CO

Dish Assembly Precision for HIRAX

Jennifer Studer, Devin Crichton, Alexandre Refregier, Keshav Bechoo, H. Cynthia Chiang, Chandrachud B. V. Dash, Sindhu Gaddam, Aditya Krishna Karigiri Madhusudhan et al.

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio interferometer array that is being deployed at the South African Radio Astronomy Observatory (SARAO) Square Kilometer Array (SKA) site in South Africa. Mapping the southern sky, its aim is to observe neutral hydrogen (HI) through intensity mapping (IM) across the redshift range of 0.78-2.55. The observation of HI makes it possible to tomographically probe large cosmological volumes, enabling constraints on, for example,…

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astro-ph.SR

Constraints from parallaxes and average period spacings in the asteroseismic study of 8 DAVs

Agnès Kim, Keaton J. Bell

With space missions such as Kepler, TESS, and Gaia, we have a wealth of data on pulsating white dwarfs that can be leveraged in white dwarf asteroseismology. We address the question of the proportion of white dwarfs with thin hydrogen layers versus those with thick hydrogen layers. We also provide a mass-radius relation for carbon-oxygen core, hydrogen atmosphere white dwarfs. Such a relationship can be used in conjunction with magnitudes and distance measurements to constrain the mass and effec…

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astro-ph.IM

Characterization and on-sky testing of photonic, AWG-based astronomical spectrographs

Jeronimo Calderon-Gomez, Frantz Martinache, Nick Cvetojevic, Marc-Antoine Martinod, Vincent Foriel, Nemanja Jovanovic, Pradip Gatkine, Gregory Sercel et al.

Astrophotonics is a field that intends to meet the needs of next-generation instruments at a small footprint, low cost, and high stability, compared to bulk-optics-based alternatives. Much development effort is driven by the stringent requirements of direct detection and characterization of exoplanets. Our team works in characterizing Arrayed-Waveguide Grating (AWG) chips for photonics-based, high-resolution, near infrared spectro-interferometry. AWG spectrographs allow to test the feasibility o…

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astro-ph.SR

Evolutionary variations of superficial iron and calcium abundance in main sequence A stars

Yu. A. Fadeyev, R. M. Bayazitov

Main sequence stellar evolution models were computed together with solution of the equations of atomic diffusion for 16 elements from hydrogen to nickel. The grid of evolutionary tracks comprises the models with stellar masses ranged from 1.4 to $2.5M_\odot$ computed for initial helium and metal abundances $Y=0.28$ and $Z=0.02$, respectively. The calculations were done for the mass loss rates $10^{-15}M_\odot/\textrm{yr}\le\dot M\le 10^{-12}M_\odot/\textrm{yr}$ as well as for $\dot M=0$. The hig…

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astro-ph.COastro-ph.IM

Impact of numerical stability in Bayesian noise wave calibration on global 21-cm experiments

Saswata Dasgupta, Adarsh Kumar Dash, Dominic Anstey, Harry T. J. Bevins, Christian Kirkham, Eloy de Lera Acedo

Detecting the global 21-cm signal from the Cosmic Dawn and Epoch of Reionization requires calibration accuracy far below the level of astrophysical foregrounds. REACH models its receiver using the noise wave formalism, with five frequency-dependent low-noise amplifier parameters fitted jointly to multiple calibration sources. We identify a numerical instability in this Bayesian calibration pipeline: the condition number of the posterior covariance matrix reaches $κ(\mathbf{V}^*) \sim 10^{9}$--$1…

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astro-ph.HE

Outflow Behavior from the Transonic Advective Disks: A Hydrodynamical Simulation Study

Sanjit Denath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan

We investigate the properties of outflows from the transonic advective accretion disk using hydrodynamical numerical simulations. We consider two different disk temperatures with an order-of-magnitude difference. For the hotter disk, we adopt initial conditions for velocity, specific angular momentum, and temperature from analytical solutions. In the colder disk case, the velocity and angular momentum profiles are kept identical, while an order of magnitude reduction in the temperature. The simu…

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astro-ph.HE

Outflow Behavior from the Transonic Advective Disks: A Hydrodynamical Simulation Study

Sanjit Debnath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan

We investigate the properties of outflows from the transonic advective accretion disk using hydrodynamical numerical simulations. We consider two different disk temperatures with an order-of-magnitude difference. For the hotter disk, we adopt initial conditions for velocity, specific angular momentum, and temperature from analytical solutions. In the colder disk case, the velocity and angular momentum profiles are kept identical, while an order of magnitude reduction in the temperature. The simu…

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hep-phastro-ph.COastro-ph.HEastro-ph.IM

Revising Indirect Dark Matter Constraints with Updated Astrophysical $J$-Factor Priors

Giacomo D'Amico

Indirect searches for particle dark matter with gamma-ray experiments have produced a large number of constraints on the annihilation cross section (or decay lifetime) over a wide range of dark matter masses. These constraints depend critically on the assumed astrophysical $J$ factor and its uncertainty, which encodes the dark matter distribution in the target and represents the dominant source of systematic uncertainty. As improved observational data and dynamical modeling are expected to revis…

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astro-ph.SRastro-ph.IM

eROSITA all-sky survey - stars and optical loading

J. Robrade, K. Dennerl, M. J. Freyberg, J. H. M. M. Schmitt

eROSITA (extended ROentgen Survey with an Imaging Telescope Array) on board the Spectrum-Roentgen-Gamma (SRG) spacecraft has performed the eROSITA All-Sky Survey (eRASS) at X-ray energies. We study the brighter stars to assess the impact of optical loading in the eROSITA all-sky survey, here specifically the eRASS:3. Further we use thermal plasma models to investigate the general properties of stellar eRASS sources and compare optical loading affected stars to coronal sources. We compare data fr…

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astro-ph.HEastro-ph.GAhep-ph

Paleodetectors for neutrino signals from diverse Galactic stellar collapses

Mahiro Yamasaki, Ken'ichiro Nakazato

The detectability of neutrinos from past Galactic core collapse supernovae (SNe) is investigated in terms of nuclear recoil tracks in ancient minerals, known as paleodetectors. To account for the diversity of core-collapse outcomes, variations in neutron star (NS) masses as well as failed SNe leading to black hole (BH) formation are taken into account. The role of the nuclear equation of state (EOS) is also considered, as it determines NS radii and maximum masses. The enhancement of sensitivity…

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astro-ph.IMastro-ph.CO

Optimizing the extraction of information from redshift probability distribution functions

Rodrigo Duarte, Valerio Marra

Photometric redshifts are essential for large-scale structure analyses, yet extracting optimal point estimates and reliability measures from the probability distribution functions (PDZs) delivered by photo-$z$ pipelines remains an open challenge. We introduce turboPDZ, a machine-learning framework that optimizes both quantities directly from the PDZ. We apply the framework to PDZs from the three independent HSC-SSP PDR3 pipelines (DEmP, DNNz, Mizuki) across Wide and DUD layers. Each PDZ is compr…

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astro-ph.SRastro-ph.EPastro-ph.GAphysics.space-ph

An interstellar energetic and non-aqueous pathway to peptide formation

Alfred Thomas Hopkinson, Ann Mary Wilson, Joe Pitfield, Alejandra Traspas Muiña, Richárd Rácz, Duncan V. Mifsud, Péter Herczku, Gergő Lakatos et al.

The origin of the molecular building blocks of life is a central question in science. A few $α$-amino acids such as glycine, the simplest proteinogenic amino acid, have been detected in meteorites and comets, indicating an extraterrestrial origin for some prebiotic molecules. However, the formation of peptides, short chains of $α$-amino acids linked by peptide bonds, under astrophysical conditions has remained unresolved. Here we show that the building blocks of proteins can form in interstellar…

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astro-ph.EPastro-ph.SR

Exploring the radial velocity variations of RY Lup with VLT/ESPRESSO: Binary versus spot hypotheses

Hala Alqubelat, Claudia Di Maio, Antonio Frasca, Carlo F. Manara, Monika G. Petr-Gotzens, Enrico Ragusa, Evelyne Alecian, Louise D. Nielsen et al.

Stellar multiplicity is a possible cause for creating protoplanetary disc substructures, as tidal forces from a close-in spectroscopic companion can carve out gaps and shape disc architecture. However, in young, active systems, the radial velocity (RV) signatures are often complicated by stellar activity. We investigate RY Lup, a classical T Tauri star hosting a disc with a ~60 au cavity, where studies with Gaia astrometry and VLT/SPHERE imaging hinted at an unseen companion. Using high-resoluti…

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astro-ph.HE

Effect of Multi-Species Plasma on Fanaroff-Riley Radio Jets

Priyesh K. Tripathi, Indranil Chattopadhyay, Raj Kishor Jpshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan

The Fanaroff-Riley (FR) dichotomy observed in extragalactic radio jets has been attributed to a range of possible mechanisms, including intrinsic jet properties such as the presence of different species in the plasma. Jet material may span from a pure electron-positron pair plasma to mixed plasmas containing electrons, positrons, and protons, or even to hadronic jets made up of electrons and protons only. To investigate this aspect, we present results from three-dimensional simulations of low-po…

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astro-ph.HE

Effect of Multi-Species Plasma on Fanaroff-Riley Radio Jets

Priyesh Kumar Tripathi, Indranil Chattopadhyay, Raj Kishor Joshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan

The Fanaroff-Riley (FR) dichotomy observed in extragalactic radio jets has been attributed to a range of possible mechanisms, including intrinsic jet properties such as the presence of different species in the plasma. Jet material may span from a pure electron-positron pair plasma to mixed plasmas containing electrons, positrons, and protons, or even to hadronic jets made up of electrons and protons only. To investigate this aspect, we present results from three-dimensional simulations of low-po…

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astro-ph.SR

Energetic Particle Acceleration and Transport: Interplanetary Coronal Mass Ejections and Shocks

Olga E. Malandraki, Christina M. S. Cohen, Joe Giacalone, Leng Ying Khoo, Domenico Trotta, Laura Rodriguez-Garcia, Athanasios Kouloumvakos, Zheyi Ding et al.

Solar Energetic Particles from suprathermal (few keV) up to relativistic (few GeV) energies constitute an important contributor to the characterization of the space environment. Emitted from the Sun they are associated with solar flares and shock waves driven by Coronal Mass Ejections. This review presents important recent results of the study of Interplanetary CMEs and shocks in relation to energetic particle acceleration and transport, taking advantage of multi-point, multi-instrument observat…

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astro-ph.GAastro-ph.IMgr-qc

Effects of a disk structure on stellar motion at the Galactic Center

Arianna Foschi, Frederic H. Vincent, Thibaut Paumard, Guy Perrin

Stellar orbits are key for probing the environment of the supermassive black hole at the Galactic Center, Sagittarius A$^*$. So far, the mass around SgrA$^*$ has been assumed to be spherically distributed. However, the extended mass may instead be flattened, creating disk-like structures. We investigate the effects that a thin disk structure would have on stars at the Galactic Center, focusing on star S2 and S301 and the clockwise stellar disk. We derive analytically the acceleration exerted by…

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astro-ph.SRastro-ph.EPphysics.space-ph

The Internal Magnetic Field Structure of ICMEs in the Heliosphere

Ziwei Huang, Zhenjun Zhou, Yudong Ye, Ming Xiong, Yuming Wang, Yutian Chi, Daniel Heyner, Hans-Ulrich Auster et al.

Interplanetary coronal mass ejections (ICMEs) are major drivers of heliospheric disturbances and space-weather effects. Here we present a multi-spacecraft study of 96 magnetic clouds (MCs) distributed over a broad range of heliocentric distances, and reconstruct their internal magnetic structure with a uniform-twist Gold--Hoyle (GH) flux-rope model. From the fits, we derive the axial field strength $B_0$, the twist density (turn density) $τ$, the GH parameter $ω$, and the integrated twist number…

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