Tootfinder

White dwarf-neutron star binaries: a plausible pathway for long-duration gamma-ray bursts from compact object mergers?
A. A. Chrimes, N. Gaspari, A. J. Levan, M. M. Briel, J. J. Eldridge, B. P. Gompertz, G. Nelemans, A. E. Nugent, J. C. Rastinejad, W. G. J. van Zeist
https://arxiv.org/abs/2508.10984

White dwarf-neutron star binaries: a plausible pathway for long-duration gamma-ray bursts from compact object mergers?
Two long-duration gamma-ray bursts were recently discovered with kilonovae, the signature of r-process element production in a compact binary merger, rather than supernovae. This has forced a re-evaluation of the long-established dichotomy between short bursts (< 2s, arising from compact binary mergers) and long bursts (> 2s, a class of massive star core-collapse event). We aim to determine whether white dwarf-neutron star (WDNS) and white dwarf-black hole (WDBH) mergers are plausible explanati…

Probing the Schwarzschild black hole immersed in a dark matter halo through astrophysical tests
Tursunali Xamidov, Sanjar Shaymatov, Qiang Wu, Tao Zhu
https://arxiv.org/abs/2507.13147

Probing the Schwarzschild black hole immersed in a dark matter halo through astrophysical tests
We investigate a recently derived Schwarzschild-like black hole (BH) immersed in a Dehnen-type $(α,β,γ)=(1,4,5/2)$ dark matter (DM) halo. We obtain constraints on the two model parameters, i.e., the halo core radius $r_s$ and the DM density parameter $ρ_s$ in both the weak and the strong field regimes. In the weak field, we model test particle geodesics and match the predicted perihelion shift to Mercury (Solar System) and the orbit of the S2 star data, obtaining upper limits on $r_s$ and $…

Improving cosmological reach of a gravitational wave observatory using Deep Loop Shaping
Jonas Buchli, Brendan Tracey, Tomislav Andric, Christopher Wipf, Yu Him Justin Chiu, Matthias Lochbrunner, Craig Donner, Rana X. Adhikari, Jan Harms, Iain Barr, Roland Hafner, Andrea Huber, Abbas Abdolmaleki, Charlie Beattie, Joseph Betzwieser, Serkan Cabi, Jonas Degrave, Yuzhu Dong, Leslie Fritz, Anchal Gupta, Oliver Groth, Sandy Huang, Tamara Norman, Hannah Openshaw, Jameson Rollins, Greg Thornto…

Improving cosmological reach of a gravitational wave observatory using Deep Loop Shaping
Improved low-frequency sensitivity of gravitational wave observatories would unlock study of intermediate-mass black hole mergers, binary black hole eccentricity, and provide early warnings for multi-messenger observations of binary neutron star mergers. Today's mirror stabilization control injects harmful noise, constituting a major obstacle to sensitivity improvements. We eliminated this noise through Deep Loop Shaping, a reinforcement learning method using frequency domain rewards. We proved…

Assembling GW231123 in star clusters through the combination of stellar binary evolution and hierarchical mergers
Lavinia Paiella, Cristiano Ugolini, Mario Spera, Marica Branchesi, Manuel Arca Sedda
https://arxiv.org/abs/2509.10609

Assembling GW231123 in star clusters through the combination of stellar binary evolution and hierarchical mergers
GW231123 is the most massive binary black hole (BBH) merger detected to date by the LIGO-Virgo-KAGRA collaboration. With at least one black hole (BH) in the upper-mass gap and both BHs exhibiting high spins ($χ_{1,2} \gtrsim 0.8$), this event challenges standard isolated binary evolution models. A compelling alternative is a dynamical origin in star clusters, where stellar binaries and hierarchical mergers may both contribute to the formation of similar BBHs. In this work, we investigate the f…

Star-Black Hole Interactions in Young Star Clusters
Sara Rastello, Giuliano Iorio, Mark Gieles, Long Wang
https://arxiv.org/abs/2509.12318 https://arxiv.or…

Star-Black Hole Interactions in Young Star Clusters
Close encounters between stars and black holes can trigger micro-tidal disruption events (micro-TDEs) in dense young star clusters (YSCs). Using direct N-body simulations with PETAR, we found that most micro-TDEs arise from few-body multiple encounters. The inferred rate is approximately 350-450 Gpc$^{-3}$ yr$^{-1}$. Micro-TDEs could be detected both by upcoming surveys such as LSST, expected to observe roughly 10-100 events per year, and by their gravitational-wave (GW) signals peaking in the …

Observable thin accretion disk around a self-dual black hole in loop quantum gravity
Tursunali Xamidov, Javokhir Sharipov, Sanjar Shaymatov
https://arxiv.org/abs/2509.10953 http…

Observable thin accretion disk around a self-dual black hole in loop quantum gravity
In this paper, we study a self-dual black hole (BH) in Loop Quantum Gravity (LQG), analyzing both timelike and null geodesics. Using observational data from Mercury's perihelion shift and the orbit of the S2 star around Sagittarius A$^{\star}$ (Sgr A$^{\star}$), we derive constraints on the polymeric function $P$. We further investigate photon trajectories near the self-dual BH under various scenarios to explore their observational relevance. Finally, we examine the properties of accretion disk…

Evidence for an Instability-induced Binary Merger in the Double-peaked, Helium-rich Type IIn #Supernova 2023zkd: https://iopscience.iop.org/article/10.3847/1538-4357/adea38 -> AI Helps Astronomers Discover a New Type of Supernova: https://www.cfa.harvard.edu/news/ai-helps-astronomers-discover-new-type-supernova - astronomers have discovered what may be a massive star exploding while trying to swallow a black hole, offering an explanation for one of the strangest supernovae ever seen.

Complex spectral variability and hints of a luminous companion in the Be star black hole binary candidate ALS 8814
Kareem El-Badry, Matthias Fabry, Hugues Sana, Tomer Shenar, Rhys Seeburger
https://arxiv.org/abs/2509.01545

Complex spectral variability and hints of a luminous companion in the Be star + black hole binary candidate ALS 8814
The emission-line binary ALS 8814 was recently proposed as a Be star + black hole (BH) binary based on large-amplitude radial velocity (RV) variations of a Be star and non-detection of spectroscopic features from a luminous companion. We reanalyze low- and medium-resolution LAMOST spectra of ALS 8814 and show that the system's spectroscopic variability is considerably more complex than previously recognized. Inspection of the system's trailed spectra reveals the presence of a second set of abso…

Impact of black hole spin on low-mass black hole-neutron star mergers
Rahime Matur, Ian Hawke, Nils Andersson
https://arxiv.org/abs/2508.06341 https://arxi…

Impact of black hole spin on low-mass black hole-neutron star mergers
The recent detection of GW230529 suggests that black hole-neutron star mergers may involve low-mass black holes, potentially producing detectable electromagnetic counterparts. Motivated by this, we perform eleven fully general-relativistic hydrodynamic simulations with and without neutrino treatment, targeting the inferred chirp mass of GW230529. We systematically vary the black hole spin from $a_{\mathrm{BH}} = 0.0$ to $0.8$ in steps of $0.1$, making this the most comprehensive study of spin e…

Formation of Cosmic Noon Protogalaxies via Quasar-Induced Fragmentation of a Cosmic Filament
Marko Mi\'ci\'c, Themiya Nanayakkara, Xinyu Dai, Jeremy Bailin, Miljan Kol\v{c}i\'c
https://arxiv.org/abs/2509.10670

Formation of Cosmic Noon Protogalaxies via Quasar-Induced Fragmentation of a Cosmic Filament
When black hole jets encounter ambient medium, they can compress the gas, trigger star formation, and create stellar clusters containing tens of thousands of stars. Here, we report a remarkable discovery of such a phenomenon that happened just 2.2 billion years after the Big Bang, during the Cosmic Noon era. Quasar SDSSJ141924.44+532315.5, powered by a one-billion-solar-mass black hole, is seen blasting a powerful jet that interacts with a hypermassive gas reservoir, creating a fascinating, clu…

So @… blew my mind about how are smart TVs are spying on us with Automatic Content Recognition and other advertising profile scripts. Yikes! Thanks for the heads up!
https://youtu.b…

Challenging a binary neutron star merger interpretation of GW230529
Ivan Markin, Anna Puecher, Mattia Bulla, Tim Dietrich
https://arxiv.org/abs/2508.08750 https://

Challenging a binary neutron star merger interpretation of GW230529
GW230529_181500 represented the first gravitational-wave detection with one of the component objects' mass inferred to lie in the previously hypothesized mass gap between the heaviest neutron stars and the lightest observed black holes. Given the expected maximum mass values for neutron stars, this object was identified as a black hole, and, with the secondary component being a neutron star, the detection was classified as a neutron star-black hole merger. However, due to the low signal-to-nois…

MESA-QUEST: Modeling Quasi-Stars in MESA
Claire B. Campbell, Andrew D. Santarelli, Matthew E. Caplan
https://arxiv.org/abs/2507.12651 https://

MESA-QUEST: Modeling Quasi-Stars in MESA
Supermassive black hole formation remains an unsolved problem. Quasi-stars have been suggested as a viable heavy-seeding mechanism. In this work, we implement methods for modeling quasi-stars previously used with the Cambridge STARS code into the 1D stellar evolution code MESA. The computational capabilities of MESA allow for more detailed simulations of quasi-star evolution due to its modularity and the ease of implementing of new physical processes and controls. Our implementation, the MESA Q…

Vacuum polarization in the horizonless Bardeen metric
Andr\'es Boasso, Francisco D. Mazzitelli
https://arxiv.org/abs/2508.06465 https://arxiv.org/pdf/2…

Vacuum polarization in the horizonless Bardeen metric
We compute the renormalized stress-energy tensor for a massless quantum scalar field in the background of the horizonless Bardeen spacetime. Within the weak-field approximation, we show that the vacuum fluctuations differ significantly between conformally and non-conformally coupled fields, both in magnitude and in their behavior at short and intermediate distances. At large distances, we recover the universal asymptotic behavior previously observed in black hole and Newtonian star backgrounds.…

From Capture to Collapse: Revisiting Black Hole formation by Fermionic Asymmetric Dark Matter in Neutron Stars
Sandra Robles, Drona Vatsyayan, Giorgio Busoni
https://arxiv.org/abs/2507.22881

From Capture to Collapse: Revisiting Black Hole formation by Fermionic Asymmetric Dark Matter in Neutron Stars
Fermionic asymmetric dark matter (ADM) can be captured in neutron stars (NSs) via scatterings with the star constituents. The absence of dark matter annihilation due to its asymmetric nature leads to ADM accumulation in the NS core, potentially reaching densities sufficient to exceed the Chandrasekhar limit and trigger its gravitational collapse into a black hole (BH), eventually consuming the NS from within. Therefore, the existence and observation of old neutron stars provides a means to cons…

Black hole accretion, star formation, and chemical evolution with PRIMA/FIRESS spectroscopy: toward the cosmic noon and beyond
Juan Antonio Fern\'andez-Ontiveros, Luigi Spinoglio, Tohru Nagao
https://arxiv.org/abs/2509.06954

Black hole accretion, star formation, and chemical evolution with PRIMA/FIRESS spectroscopy: toward the cosmic noon and beyond
The PRobe far-Infrared Mission for Astrophysics (PRIMA) will deliver the first comprehensive view of the obscured side of star formation and black hole accretion that dominates galaxy growth at cosmic noon. Around 90% of UV/optical photons from young stars and Active Galactic Nuclei (AGN) are absorbed by dust and reradiated in the mid- to far-infrared, where key diagnostic lines trace accretion, star formation, and the physical and chemical conditions of galaxies. PRIMA will conduct blind spect…

Mass Distribution of Binary Black Hole Mergers from Young and Old Dense Star Clusters
Claire S. Ye (CITA), Maya Fishbach, Kyle Kremer, Marta Reina-Campos
https://arxiv.org/abs/2507.07183

Mass Distribution of Binary Black Hole Mergers from Young and Old Dense Star Clusters
Dense star clusters are thought to contribute significantly to the merger rates of stellar-mass binary black holes (BBHs) detected by the LIGO-Virgo-KAGRA collaboration. We combine $N$-body dynamic models of realistic dense star clusters with cluster formation histories to estimate the merger rate distribution as a function of primary mass for merging BBHs formed in these environments. It has been argued that dense star clusters -- most notably old globular clusters -- predominantly produce BBH…

Double Compact Binary Merger Rate Density in Open Star Clusters: Black Holes, Neutron Stars, and White Dwarfs
Savannah Cary, Michiko Fujii, Long Wang, Ataru Tanikawa
https://arxiv.org/abs/2506.22673

Double Compact Binary Merger Rate Density in Open Star Clusters: Black Holes, Neutron Stars, and White Dwarfs
Studying compact-object binary mergers in star clusters is crucial for understanding stellar evolution and dynamical interactions in galaxies. Open clusters in particular are more abundant over cosmic time than globular clusters, however, previous research on low-mass clusters with $\lesssim 10^3~\textrm{M}_{\odot}$ has focused on binary black holes (BBHs) or black hole-neutron star (BH-NS) binaries. Binary mergers of other compact objects, such as white dwarfs (WDs), are also crucial as progen…

Short GRB 090510: a magnetized neutron star binary merger leading to a black hole
J. A. Rueda, R. Ruffini, Yu Wang
https://arxiv.org/abs/2509.08172 https://

Short GRB 090510: a magnetized neutron star binary merger leading to a black hole
We model the short gamma-ray bursts (GRB) 090510 as the product of a magnetized neutron star (NS) binary merger. Accounting for the NS critical mass constraint given by the mass of PSR J0952--0607, we infer that GRB 090510 was a highly-magnetized NS-NS merger that left as remnant a Kerr black hole (BH) of $2.4 M_\odot$ with a low-mass accretion disk. The gamma-ray precursor is powered by the magnetic energy released during the merger of the NSs. The prompt emission originates at the transparenc…

Fueling, Evolution, and Diversity of AGN in Dwarf Galaxies: Insights from Star Formation and Black Hole Scaling Relations
G. Mountrichas, M. Siudek, F. J. Carrera
https://arxiv.org/abs/2509.03590

Fueling, Evolution, and Diversity of AGN in Dwarf Galaxies: Insights from Star Formation and Black Hole Scaling Relations
We investigate the star formation activity and black hole scaling relations in a sample of 1451 AGN hosted by dwarf galaxies at redshift 0.5 to 0.9, drawn from the VIPERS survey. The sample comprises Seyferts and LINERs identified through emission-line diagnostics, as well as IR-selected AGN based on WISE colors. Using the parameter SFRnorm, defined as the ratio of the SFR of a galaxy hosting an AGN to the median SFR of star-forming galaxies of similar stellar mass and redshift, we compare AGN …

A case study of GW190425 for classifying binary neutron star versus binary black hole mergers and constraining asymmetric dark matter with gravitational wave detectors
Sanika Khadkikar, Divya Singh
https://arxiv.org/abs/2507.07895

A case study of GW190425 for classifying binary neutron star versus binary black hole mergers and constraining asymmetric dark matter with gravitational wave detectors
The LIGO Scientific, Virgo, and KAGRA collaboration has identified two binary neutron star merger candidates, GW170817 and GW190425, along with several binary black hole candidates. While GW170817 was confirmed as a BNS merger through its electromagnetic counterparts, GW190425 lacked such observations, leaving its classification uncertain. We examine the possibility that GW190425 originated from black holes that merged after dark matter accretion caused their progenitor neutron stars to implode…

Enhanced Star Formation and Black Hole Accretion Rates in Galaxy Mergers in IllustrisTNG50
Aimee L. Schechter, Shy Genel, Bryan Terrazas, Julia M. Comerford, Abigail Hartley, Rachel S. Somerville, Rebecca Nevin, Joseph Simon, Erica Nelson
https://arxiv.org/abs/2507.01092

Enhanced Star Formation and Black Hole Accretion Rates in Galaxy Mergers in IllustrisTNG50
Many theoretical and observational studies have suggested that galaxy mergers may trigger enhanced star formation or active galactic nuclei (AGN) activity. We present an analysis of merging and nonmerging galaxies from $0.2 \leq z \leq 3$ in the IllustrisTNG50 simulation. These galaxies encompass a range of masses ($M_\star > 10^{8}M_\odot$), multiple merger stages, and mass ratios ($\geq1:10$). We examine the effect that galaxy mergers have on star formation and black hole accretion rates in t…

Constraining the Cosmological Constant from Stellar Orbits Around Sgr A* Using Physics-Informed Neural Networks
Shinsei Eyama, Youhei Masada
https://arxiv.org/abs/2508.19719 htt…

Constraining the Cosmological Constant from Stellar Orbits Around Sgr A* Using Physics-Informed Neural Networks
We present a novel analytical framework employing Physics-Informed Neural Networks (PINNs) to constrain the cosmological constant $Λ$ through the analysis of stellar orbits around the supermassive black hole (SMBH) Sgr A* at the Galactic center. Focusing on the well-observed S2 star, we use an inverse PINN (iPINN) architecture to infer orbital elements and estimate the total precession angle from astrometric data. By isolating the contribution from $Λ$, which is defined as the difference betw…

Early Warning From Eccentric Compact Binaries: Template Initialization And Sub-dominant Mode Effects
Priyanka Sinha, R. Prasad, Mukesh Kumar Singh, Prayush Kumar, Akash Maurya, Kaushik Paul
https://arxiv.org/abs/2507.07021

Early Warning From Eccentric Compact Binaries: Template Initialization And Sub-dominant Mode Effects
Early warning of gravitational waves (GWs) is essential for multi-messenger observations of binary neutron star and black hole-neutron star merger events. In this study, we investigate early warning prospects from eccentric compact binaries, whose mergers are expected to comprise a significant fraction of detected GW events in the future. Eccentric binaries exhibit oscillatory frequency evolution, causing GW frequencies to recur multiple times through their coalescence. Consequently, generating…

Prominence: A discriminator of gravitational wave signals
Jo\~ao Gon\c{c}alves, Danny Marfatia, Ant\'onio P. Morais
https://arxiv.org/abs/2509.04384 https://

Prominence: A discriminator of gravitational wave signals
The concept of prominence is familiar to signal engineers, topographers and mountaineers. We introduce Prominence $\mathcal P$ as a discriminator of gravitational wave (GW) signals. We treat black hole and neutron star binaries as astrophysical background sources, and show how $\mathcal P$ can be used to distinguish between GW spectra produced by first-order phase transitions, domain walls and cosmic strings, and combinations thereof. Prominence can also be used to discriminate between these an…

Beyond Hierarchical Mergers: Accretion-Driven Origins of Massive, Highly Spinning Black Holes in Dense Star Clusters
Fulya K{\i}ro\u{g}lu, Kyle Kremer, Frederic A. Rasio
https://arxiv.org/abs/2509.05415

Beyond Hierarchical Mergers: Accretion-Driven Origins of Massive, Highly Spinning Black Holes in Dense Star Clusters
GW231123, the most massive binary black hole (BBH) merger detected by LIGO/Virgo/KAGRA, highlights the need to understand the origins of massive, high-spin stellar black holes (BHs). Dense star clusters provide natural environments for forming such systems, beyond the limits of standard massive star evolution to core collapse. While repeated BBH mergers can grow BHs through dynamical interactions (the so-called "hierarchical merger" channel), most star clusters with masses $\lesssim 10^6\,M_\od…

Testing modified gravity with the eccentric neutron star--black hole merger GW200105
Soumen Roy, Justin Janquart
https://arxiv.org/abs/2507.21315 https://a…

Testing modified gravity with the eccentric neutron star--black hole merger GW200105
Direct detections of gravitational waves offer a unique opportunity to test gravity in the highly dynamical and strong field regime. Current tests are typically performed assuming signals from quasi-circular binaries. However, the complex waveform morphology induced by orbital eccentricity can enhance our ability to probe gravity with greater precision. A recent analysis of the neutron star-black hole event GW200105 identified strong evidence for orbital eccentricity. We extend an eccentric-pre…

Analogue simulation of quantum gravity black hole models in a dc-SQUID array
Marco D. Maceda, Carlos Sab\'in
https://arxiv.org/abs/2507.14150 https://

Analogue simulation of quantum gravity black hole models in a dc-SQUID array
We propose an analog quantum simulation for studying the collapse and bounce of a star from infinity. In this spacetime, which encompasses both a black hole and a white hole, we place a massless scalar field that propagates at the speed of light, which is modified by the curvature. We simulate this system using an SQUID array, in which we can alter the propagation of light using an external magnetic field. We consider both infalling and outfalling radiation, giving rise to two different scenari…

Cosmic Threads: Interlinking the Stellar Initial Mass Function from Star-Birth to Galaxies
Tereza Jerabkova, Donatella Romano, Pavel Kroupa, Philippe Andr\'e, Martyna Chru\'sli\'nska, Fabio Fontanot, Andrew Hopkins, Vikrant Jadhav, Natalia Lah\'en, Yueh-Ning Lee, Alessio Mucciarelli, Stefania Salvadori, Long Wang, Zhiqiang Yan, Morten Andersen, Anna Durrant, Fabien Louvet, Mariya Lyubenova, Francesca Matteucci, Piyush Sharda, Glenn van de Ven, Alexandre Vazdekis

Cosmic Threads: Interlinking the Stellar Initial Mass Function from Star-Birth to Galaxies
The stellar initial mass function (sIMF) describes the distribution of stellar masses formed in a single star formation event in a molecular cloud clump. It is fundamental to astrophysics and cosmology, shaping our understanding of unresolved stellar populations, galactic chemical enrichment and habitable zones, and black hole growth. This White Paper reviews studies on the core mass function, stellar multiplicity, and dynamical processes affecting sIMF determinations, as well as the link betwe…

Gaia's promise to detect compact-object binaries: where we stand with the third data release
Chirag Chawla, Sourav Chatterjee, Katelyn Breivik
https://arxiv.org/abs/2508.21805

Gaia's promise to detect compact-object binaries: where we stand with the third data release
With its third data release (DR3), Gaia begins unveiling dormant candidate compact object (CO) binaries with luminous companion (LC) as predicted by several past theoretical studies. To date, 3 black hole (BH), 21 neutron star (NS), and ~3200 white dwarf (WD) candidates have been identified with LCs in detached orbits using astrometry. We adopt an observationally motivated sampling scheme for the star formation history of the Milky Way, and initial zero-age main-sequence binary properties, inco…

The Impact of Natal Kicks on Black Hole Binaries
Alejandro Vigna-G\'omez
https://arxiv.org/abs/2507.07573 https://arxiv.org/pdf/2…

The Impact of Natal Kicks on Black Hole Binaries
In massive binary-star systems, supernova explosions can significantly alter the orbit during the formation of compact objects. Some compact objects are predicted to form via direct collapse, a scenario with negligible mass loss and no baryonic ejecta emitted. In this scenario, most of the energy is released via neutrinos, and any resulting natal kick arises from asymmetries in their emission. Here I investigate stellar collapse leading to binary black hole (BH) formation, with a focus on how t…

From a collapsing radiating star to an evaporating black hole: A smooth transition from classical to quantum entropy
Sarbari Guha, Shamima Khan, Rituparno Goswami
https://arxiv.org/abs/2507.16485

From a collapsing radiating star to an evaporating black hole: A smooth transition from classical to quantum entropy
We present a robust mechanism where the geometrical free-gravitational entropy of an isolated astrophysical radiating star undergoing continual gravitational collapse, as measured by an external observer, makes a smooth transition to the Bekenstein-Hawking entropy at the onset of the horizon formation and in the late times of black hole evaporation. It is interesting to note that both in the classical regime and the semi classical evaporating black hole regime, the matter is radiated via the Va…

Detectability of compact intermediate-mass black hole binaries as low-frequency gravitational wave sources: the influence of dynamical friction of dark matter
Wen-Qing Jia, Wen-Cong Chen
https://arxiv.org/abs/2508.03582

Detectability of compact intermediate-mass black hole binaries as low-frequency gravitational wave sources: the influence of dynamical friction of dark matter
The black hole (BH) spin could significantly change the density of dark matter (DM) in its vicinity, creating a mini-spike of the density of DM. The dynamical friction (DF) between DM and the companion star of a BH can provide an efficient loss of angular momentum, driving the BH-main sequence (MS) star binary to evolve toward a compact orbit system. We investigate the influence of the DF of DM on the detectability of intermediate-mass black hole (IMBH)-MS binaries as low-frequency gravitationa…

Mergers Fall Short: Non-merger Channels Required for Galactic Heavy Element Production
Muhammed Saleem, Hsin-Yu Chen, Daniel M. Siegel, Philippe Landry, Jocelyn S. Read, Kaile Wang
https://arxiv.org/abs/2508.06020

Mergers Fall Short: Non-merger Channels Required for Galactic Heavy Element Production
Since the discovery of the binary neutron star merger GW170817 and its associated kilonova, neutron star mergers have been established as a key production channel for $r$-process elements in the Universe. However, observations of $r$-process abundances as inferred from stellar spectra of Milky Way disk stars, together with chemical evolution modeling, suggest that additional channels are needed to fully account for the $r$-process element enrichment in the Milky Way. Neutron star-black hole mer…

Black hole spectroscopy of collapsing and merging neutron stars
Oliver Steppohn, Sebastian H. V\"olkel, Tim Dietrich
https://arxiv.org/abs/2508.15534 https://

Black hole spectroscopy of collapsing and merging neutron stars
Black hole spectroscopy is an important pillar when studying gravitational waves from black holes and enables tests of general relativity. Most of the gravitational-wave signals observed over the last decade originate from binary black hole systems. Binary neutron star or black hole-neutron star systems are rarer but of particular interest for the next-generation ground-based gravitational-wave detectors. These events offer the exciting possibility of studying matter effects on the ringdown of …

Further evidence for natal kick segregation by spectral type in high-mass X-ray binaries
Pornisara Nuchvanichakul, Poshak Gandhi, Christian Knigge, Yue Zhao, Puji Irawati, Suwicha Wanawichian, Cordelia Dashwood Brown
https://arxiv.org/abs/2509.10221

Further evidence for natal kick segregation by spectral type in high-mass X-ray binaries
High-mass X-ray binaries (HMXBs) are systems in which a neutron star or black hole accretes material from a massive companion. HMXBs are expected to have experienced a supernova in their evolution. The impulsive kick associated with this event should affect the space velocity of the system in a way that depends on the nature and state of the progenitor binary. Here, we test whether the different evolutionary histories of HMXBs have left a detectable imprint on their peculiar velocities ($V_{\rm…

Using gravitational wave dark sirens to choose between host galaxy weighting models
Zhuotao Li, Rachel Gray, Ik Siong Heng
https://arxiv.org/abs/2508.15574 https://

Using gravitational wave dark sirens to choose between host galaxy weighting models
Binary black hole (BBH) mergers,, an important source of gravitational-waves(GWs), are assumed to be hosted in galaxies. The probability of a galaxy to host a BBH is related to its properties, for example stellar mass and star formation rate. These properties can be estimated from observables, such as the luminosity in certain observation bands. We refer to this description of host galaxy properties as host galaxy weighting models. However, the host galaxy weighting model for BBHs has yet to be…

Horizonless star based on regular black hole with finite radius and its observational signatures
M. F. Fauzi, B. N. Jayawiguna, H. S. Ramadhan, A. Sulaksono
https://arxiv.org/abs/2508.18072

Horizonless star based on regular black hole with finite radius and its observational signatures
The horizonless configuration of regular black holes has recently attracted attention as a model for ultracompact stars. In this paper, we propose a new class of regular black hole models sourced by a de Sitter vacuum with a finite radius. We focus on studying its horizonless configuration, which is modified into an anisotropic gravastar by proposing an ansatz of equation of states. We confirm that an anisotropic gravastar approaching horizon formation must violate the dominant energy condition…

Understanding the Evolution of Black Hole Accretion and Dust out to z=4 with a Deep Imaging Extragalactic Survey with PRIMA
Andreas L. Faisst, Chian-Chou Chen, Laure Ciesla, Carlotta Gruppioni
https://arxiv.org/abs/2509.01674

Understanding the Evolution of Black Hole Accretion and Dust out to z=4 with a Deep Imaging Extragalactic Survey with PRIMA
The cosmic evolution of obscured star formation, dust properties and production mechanisms, and the prevalence of dust-obscured AGN out to high redshifts are currently some of the hot topics in astrophysics. While much progress has been made in the early days with Spitzer and Herschel, these facilities have not reached the necessary depths to observe the mid-IR light of high-redshift (z > 3) galaxies. Recently, the James Webb Space Telescope (JWST) has filled in the blue side of the rest-frame …

A Black Hole is Born: 3D GRMHD Simulation of Black Hole Formation from Core-Collapse
Goni Halevi, Swapnil Shankar, Philipp M\"osta, Roland Haas, Erik Schnetter
https://arxiv.org/abs/2506.20837

A Black Hole is Born: 3D GRMHD Simulation of Black Hole Formation from Core-Collapse
We present the first three-dimensional, fully general-relativistic magnetohydrodynamic (3D GRMHD) simulation of a black hole (BH) formed from the collapsed core of a massive star. The ability to self-consistently capture the birth of a compact remnant in 3D is crucial for modeling natal BH properties (including masses, spins, and kicks), which are of particular interest in the era of gravitational wave astronomy. However, such simulations have remained elusive due to extreme computational chall…

Supermassive black hole growth from stellar binary encounters
Aubrey Jones, Benjamin C. Bromley
https://arxiv.org/abs/2509.02316 https://arxiv.org/pdf/2509…

Supermassive black hole growth from stellar binary encounters
The growth of supermassive black holes (SMBHs) remains a central problem in astrophysics, with current observations providing only limited constraints on the underlying mechanisms. One possible growth channel is stellar accretion via the Hill's mechanism, wherein a SMBH tidally breaks up a passing binary star, capturing and eventually accreting a member of the binary. We adopt a model to predict capture rates from parameters that include the central number density of stars, the stellar velocity…

Remnant properties of binary neutron star mergers undergoing prompt collapse
Arnab Dhani, Alessandro Camilletti, David Radice, Rahul Kashyap, Bangalore Sathyaprakash, Domenico Logoteta, Albino Perego
https://arxiv.org/abs/2507.19431

Remnant properties of binary neutron star mergers undergoing prompt collapse
We study the properties of remnants formed in prompt-collapse binary neutron star mergers. We consider non-spinning binaries over a range of total masses and mass ratios across a set of 22 equations of state, totaling 107 numerical relativity simulations. We report the final mass and spin of the systems (including the accretion disk and ejecta) to be constrained in a narrow range, regardless of the binary configuration and matter effects. This sets them apart from binary black-hole merger remna…

Probing the peak of star formation with the stochastic background of binary black hole mergers
Nico Bers, Sylvia Biscoveanu
https://arxiv.org/abs/2506.21868

Probing the peak of star formation with the stochastic background of binary black hole mergers
Although the LIGO-Virgo-KAGRA collaboration detects many individually resolvable gravitational-wave events from binary black hole mergers, those that are too weak to be identified individually contribute to a stochastic gravitational-wave background. Unlike the standard cross-correlation search for excess correlated power, a Bayesian search method that models the background as a superposition of an unknown number of mergers enables simultaneous inference of the properties of high-redshift binar…

Where are Gaia's small black holes?
M. Fishbach, K. Breivik, R. Willcox, L. A. C van Son
https://arxiv.org/abs/2508.08986 https://arxiv.org/pdf/2508.08…

Where are Gaia's small black holes?
Gaia has recently revealed a population of over 20 compact objects in wide astrometric binaries, while LIGO-Virgo-KAGRA (LVK) have observed around 100 compact object binaries as gravitational-wave (GW) mergers. Despite belonging to different systems, the compact objects discovered by both Gaia and the LVK follow a multimodal mass distribution, with a global maximum at neutron star (NS) masses ($\sim 1$-$2\,M_\odot$) and a secondary local maximum at black hole (BH) masses $\sim10\,M_\odot$. Howe…

Polarimetric Diversity in Tidal Disruption Events: Comparative Study of Low-Polarised sources with AT2020mot
A. Floris, I. Liodakis, K. I. I. Koljonen, E. Lindfors, B. Ag\`is-Gonzalez, A. Paggi, D. Blinov, K. Nilsson, I. Agudo, P. Charalampopoulos, M. A. D\`iaz Teodori, J. Escudero Pedrosa, J. Otero-Santos, V. Piirola, M. Newsome, S. Van Velzen
https://

Polarimetric Diversity in Tidal Disruption Events: Comparative Study of Low-Polarised sources with AT2020mot
Tidal disruption events (TDEs) occur when a star is disrupted by the tidal forces of a supermassive black hole (SMBH), producing bright multi-wavelength flares. Among these events, AT2020mot has so far exhibited the highest recorded optical polarisation, with tidal shocks proposed as the primary source of its polarised emission. We present a comprehensive analysis of 13 TDEs with available polarimetric observations, aiming to determine whether the unusually high polarisation of AT2020mot stems …

When Stars Mimic Monsters: Luminous Blue Variables in SBS 0335-052 E
Zixuan Peng, Crystal L. Martin, Jiamu Huang, Nikolaus Z. Prusinski, Chenliang Huang, Zhuyun Zhuang, Yuan Li, Tin Long Sunny Wong, Jiayang Yang, Joseph F. Hennawi
https://arxiv.org/abs/2508.03912

When Stars Mimic Monsters: Luminous Blue Variables in SBS 0335-052 E
Recent studies have claimed the detection of an active massive black hole (BH) in the low-metallicity blue compact dwarf galaxy SBS 0335-052 E based on near-infrared (NIR) time variability and broad H$α$ wings. This interpretation remains questionable given the observed broad wings in forbidden [O III] emission. Based on spectroscopic properties derived from our KCWI/KCRM integral-field observation of super star clusters 1 and 2 (SSCs 1$\&$2), we propose instead that these BH signatures origin…

Nine tidal disruption event candidates in eROSITA-DE DR1 discovered through supersoft X-ray selection
R. A. J. Eyles-Ferris, R. L. C. Starling, P. T. O'Brien, K. L. Page, P. A. Evans
https://arxiv.org/abs/2508.08389

Nine tidal disruption event candidates in eROSITA-DE DR1 discovered through supersoft X-ray selection
Tidal disruption events are rare and diverse transients that occur when a star is torn apart by a supermassive black hole and accreted, which can result in a supersoft X-ray thermal transient. Here, we present nine tidal disruption event (TDE) candidates identified in eROSITA-DE Data Release 1 through a novel search for such supersoft sources. We select candidates by comparing the catalogued count rates in several combinations of bands and evaluate the nature of selected sources to produce our …

Leveraging NRTidalv3 to develop gravitational waveform models with higher-order modes for binary neutron star systems
Adrian Abac, Felip Ramis Vidal, Marta Colleoni, Anna Puecher, Alejandra Gonzalez, Tim Dietrich
https://arxiv.org/abs/2507.15426

Leveraging NRTidalv3 to develop gravitational waveform models with higher-order modes for binary neutron star systems
Accurate and reliable gravitational waveform models are crucial in determining the properties of compact binary mergers. In particular, next-generation gravitational-wave detectors will require more accurate waveforms to avoid biases in the analysis. In this work, we extend the recent NRTidalv3 model to account for higher-mode corrections in the tidal phase contributions for binary neutron star systems. The higher-mode, multipolar NRTidalv3 model is then attached to several binary-black-hole ba…

Reprocessing of X-rays emission in Ultra-Luminous X-ray sources
Manish Kumar, Rahul Sharma, Biswajit Paul
https://arxiv.org/abs/2509.09133 https://arxiv.or…

Reprocessing of X-rays emission in Ultra-Luminous X-ray sources
With the discovery of pulsations in some of the ultra-luminous X-ray sources (ULXs), it is quite clear that most of the ULXs harbor either a neutron star or a stellar mass black hole as a compact object accreting at super-Eddington rates. In spite of having such a high accretion rate, the reprocessed emission in the ULX sources is quite meagre compared to that observed in Galactic X-ray binaries, except for some absorption lines in the winds. In this work, we investigate the extent of reprocess…

Pregalactic globular cluster formation
Jeremy Mould, Jarrod Hurley
https://arxiv.org/abs/2509.02165 https://arxiv.org/pdf/2509.02165

Pregalactic globular cluster formation
The QCD phase transition in the early universe may provide primordial black hole nuclei for globular clusters. We consider the accretion and star formation that follow, once 1000 solar mass nuclei have formed. When such a nucleus has formed, it remains. Whether these are common in the oldest globular clusters is one decidedly challenging question for the model, which is, as yet, unanswered; another is a possible contribution to the cosmic gravitational radiation background.

Identifying potential binary neutron star merger events from the Fermi GBM Gamma-Ray Burst Catalog
I. F. Giudice, L. Izzo, R. Martone, M. T. Botticella, E. Cappellaro, R. De Rosa, M. Della Valle
https://arxiv.org/abs/2507.18258

Identifying potential binary neutron star merger events from the Fermi GBM Gamma-Ray Burst Catalog
Short gamma-ray bursts are expected to be associated with compact object mergers, such as binary neutron star or neutron star-black hole systems, and are key high-energy multimessenger events. The detection of GRB 170817A, coinciding with the gravitational wave signal GW170817 from a BNS merger, confirmed the link between sGRBs and compact object mergers. Similarly, GRB 150101B displayed remarkable similarities to GRB 170817A, further supporting its association with compact binary mergers. The …

GWTC-4.0: Population Properties of Merging Compact Binaries
The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration
https://arxiv.org/abs/2508.18083

GWTC-4.0: Population Properties of Merging Compact Binaries
We detail the population properties of merging compact objects using 158 mergers from the cumulative Gravitational-Wave Transient Catalog 4.0, which includes three types of binary mergers: binary neutron star, neutron star--black hole binary, and binary black hole mergers. We resolve multiple over- and under-densities in the black hole mass distribution: features persist at primary masses of $10\,M_\odot$ and $35\,M_\odot$ with a possible third feature at $\sim 20\,M_\odot$. These are departure…

Impact of a granular mass distribution on the orbit of S2 in the Galactic center
Matteo Sadun Bordoni, Roberto Capuzzo Dolcetta, Aleksey Generozov, Guillaume Bourdarot, Antonia Drescher, Frank Eisenhauer, Reinhard Genzel, Stefan Gillessen, Simran Joharle, Felix Mang, Thomas Ott, Diogo C. Ribeiro, Sebastiano D. von Fellenberg
https://

Impact of a granular mass distribution on the orbit of S2 in the Galactic center
The orbit of the S2 star around Sagittarius A* provides a unique opportunity to test general relativity and study dynamical processes near a supermassive black hole. Observations have shown that the orbit of S2 is consistent with a Schwarzschild orbit at a 10$σ$ confidence level, constraining the amount of extended mass within its orbit to less than 1200 M$_\odot$, under the assumption of a smooth, spherically symmetric mass distribution. In this work we investigate the effects on the S2 orbit…

Radio Continuum Studies of Ultra-Compact and Short Orbital Period X-Ray Binaries
Kristen C. Dage, Teresa Panurach, Kwangmin Oh, Malu Sudha, Montserrat Armas Padilla, Arash Bahramian, Edward M. Cackett, Timothy J. Galvin, Craig O. Heinke, Renee Ludlam, Angiraben D. Mahida, Richard M. Plotkin, Thomas D. Russell, Susmita Sett, Payaswini Saikia, Aaran W. Shaw, Alexandra J. Tetarenko

Radio Continuum Studies of Ultra-Compact and Short Orbital Period X-Ray Binaries
We present the radio continuum counterparts to the enigmatic ultra-compact X-ray binaries (UCXBs); a black hole or neutron star accreting from a hydrogen-deficient white dwarf donor star, with short orbital periods ($<$ 80 minutes). For the sample of UCXBs hosted by globular clusters (GCs), we search for whether certain GC properties are more likely to enhance UCXB formation. We determine that GCs which host UCXBs are drawn from a distinct population in terms of cluster concentration, core radi…

Can "premature collapse" form black holes in the upper and lower mass gaps?
Thomas W. Baumgarte, Stuart L. Shapiro
https://arxiv.org/abs/2509.04574 https://

Can "premature collapse" form black holes in the upper and lower mass gaps?
Observations of gravitational waves from binary black hole mergers, including the recent signals GW231123 and GW230529, have revealed multiple progenitor black holes in the so-called upper and lower mass gaps, respectively. It is generally assumed that massive stars cannot form black holes in the upper mass gap because pair instabilities in the late stage of stellar evolution disrupt the stars, whereas the lower mass gap refers to the gap between the maximum allowed neutron star mass and the sm…

Hyperonic degrees of freedom in binary neutron star mergers
Laura Tolos, Hristijan Kochankovski, Angels Ramos, Georgios Lioutas, Sebastian Blacker, Andreas Bauswein
https://arxiv.org/abs/2507.18213

Hyperonic degrees of freedom in binary neutron star mergers
We analyze the influence of hyperons in binary neutron star mergers considering several different equations of state that include hyperons. By running a large set of simulations, we study the impact of the thermally produced hyperons on the gravitational-wave spectral features, the temperature evolution of the remnant, the mass ejecta and the threshold mass for prompt collapse to a black hole. Models with hyperons tend to stand out in the relation between the dominant postmerger gravitational-w…

Optical Strong Line Ratios Cannot Distinguish Between Stellar Populations and Accreting Black Holes at High Ionization Parameters and Low Metallicities
Nikko J. Cleri, Grace M. Olivier, Bren E. Backhaus, Joel Leja, Casey Papovich, Jonathan R. Trump, Pablo Arrabal Haro, Veronique Buat, Denis Burgarella, Emilie Burnham, Antonello Calabro, Jonathan H. Cohn, Justin W. Cole, Kelcey Davis, Mark Dickinson, Steven L. Finkelstein, Ray Garner III, Michaela Hirschmann, Weida Hu, Taylor A. Hutchis…

Optical Strong Line Ratios Cannot Distinguish Between Stellar Populations and Accreting Black Holes at High Ionization Parameters and Low Metallicities
High-redshift observations from JWST indicate that optical strong line ratios do not carry the same constraining power as they do at low redshifts. Critically, this prevents a separation between stellar- and black hole-driven ionizing radiation, thereby obscuring both active galactic nuclei demographics and star formation rates. To investigate this, we compute a large suite of photoionization models from Cloudy powered by stellar populations and accreting black holes over a large grid of ages, …

Resolving Black Hole Family Issues Among the Massive Ancestors of Very High-Spin Gravitational-Wave Events Like GW231123
Jakob Stegmann, Aleksandra Olejak, Selma E. de Mink
https://arxiv.org/abs/2507.15967

Resolving Black Hole Family Issues Among the Massive Ancestors of Very High-Spin Gravitational-Wave Events Like GW231123
The latest detection of GW231123, a binary black hole (BH) merger with exceptionally large masses and high spins for the incoming components, has been suggested as a smoking gun for hierarchical formation. In this scenario, a first generation of BHs resulting from collapsing stars form in a dense environment. Here they can assemble dynamically and undergo subsequent mergers. We discuss three challenges for the formation of a GW231123-like event inside a star cluster: 1) The high masses of the i…

Predicting the Properties of the Fallback Rate from Tidal Disruption Events: Investigating the Maximum Gravity Model
Julia Fancher, Ananya Bandopadhyay, Eric R. Coughlin, C. J. Nixon
https://arxiv.org/abs/2507.16912

Predicting the Properties of the Fallback Rate from Tidal Disruption Events: Investigating the Maximum Gravity Model
A star destroyed by the tidal field of a supermassive black hole (SMBH) in a tidal disruption event (TDE) gives rise to a luminous flare. TDEs are being detected at an ever-increasing rate, motivating the need for accurate models of their lightcurves. The ``maximum gravity'' (MG) model posits that a star is completely destroyed when the tidal field of the SMBH exceeds the maximum self-gravitational field within the star, $g_{\rm max}$, and predicts the peak fallback rate $\dot{M}_{\rm peak}$ an…

Magellan Spectroscopy of AGNs in Low-mass Galaxies: Scaling Relations and a Triple-Peaked AGN
Megan R. Sturm, Amy E. Reines, Jenny Greene, Sheyda Salehirad
https://arxiv.org/abs/2507.18703

Magellan Spectroscopy of AGNs in Low-mass Galaxies: Scaling Relations and a Triple-Peaked AGN
In this work, we aim to further populate the low-mass regime of black hole (BH) scaling relations to better understand the formation and growth mechanisms of central supermassive BHs. We target six galaxies that have been previously identified as hosting active galactic nuclei (AGN) based on optical spectroscopy from the Galaxy and Mass Assembly (GAMA) survey or the Sloan Digital Sky Survey (SDSS) with stellar masses reported to be M$_\star < 5 \times 10^9$ M$_\odot$. Using follow-up optical sp…

Eccentricity distribution of extreme mass ratio inspirals
Davide Mancieri, Luca Broggi, Morgan Vinciguerra, Alberto Sesana, Matteo Bonetti
https://arxiv.org/abs/2509.02394 https…

Eccentricity distribution of extreme mass ratio inspirals
We present realistic eccentricity distributions for extreme mass ratio inspirals (EMRIs) forming via the two-body relaxation channel in nuclear star clusters, tracking their evolution up to the final plunge onto the central Schwarzschild massive black hole (MBH). We find that EMRIs can retain significant eccentricities at plunge, with a distribution peaking at $e_\mathrm{pl} \approx0.2$, and a considerable fraction reaching much higher values. In particular, up to $20\%$ of the forming EMRIs fe…

Double tidal disruption events in the changing-look AGN Mrk1018
Zhang XueGuang (GXU)
https://arxiv.org/abs/2507.14428 https://arxiv.o…

Double tidal disruption events in the changing-look AGN Mrk1018
Tidal disruption events (TDEs) as excellent beacons to black hole (BH) accreting systems have been studied for more than five decades with a single star tidally disrupted by a central massive BH. However, if considering two stars passing through a central BH and being tidally disrupted in a short period, so-called double TDEs could be expected and lead to unique variability features very different from features from standard TDEs. Here, we report such oversimplified double TDEs in the known cha…

Collapsar Disk Outflows III: Detectable Neutrino and Gravitational Wave Signatures
Rodrigo Fern\'andez, Silas Janke, Coleman Dean, Irene Tamborra
https://arxiv.org/abs/2507.17836

Collapsar Disk Outflows III: Detectable Neutrino and Gravitational Wave Signatures
We investigate the neutrino and gravitational wave (GW) signals from accretion disks formed during the failed collapse of a rotating massive star (a collapsar). Following black hole formation, a neutrino-cooled, shocked accretion disk forms, which displays non-spherical oscillations for a period of seconds before becoming advective and exploding the star. We compute the neutrino and GW signals (matter quadrupole) from collapsar disks using global axisymmetric, viscous hydrodynamic simulations. …

X-ray polarization of reflected thermal emission
J. Podgorn\'y, M. Dov\v{c}iak, R. Goosmann, F. Marin, L. Marra, G. Matt, A. R\'o\.za\'nska, R. Taverna
https://arxiv.org/abs/2507.23687

X-ray polarization of reflected thermal emission
X-ray thermal emission is inherent in neutron-star and black-hole X-ray binary systems. Within these systems, it may reflect from optically thick matter, which will create characteristic observable X-ray spectro-polarimetric features. We compute rest-frame reflection spectra and the corresponding energy-dependent linear polarization degree and angle for (un)polarized single-temperature black-body spectra impinging on a partially ionized constant-density optically thick slab. We use a combinatio…

Quasi-Periodic Eruptions as a Probe of Accretion Disk in Tidal Disruption Events
Tomoya Suzuguchi, Tatsuya Matsumoto
https://arxiv.org/abs/2509.01663 https://

Quasi-Periodic Eruptions as a Probe of Accretion Disk in Tidal Disruption Events
Quasi-periodic eruptions (QPEs) are X-ray transients characterized by nearly regular recurring flares from galactic nuclei. Recent observations have confirmed that some QPEs occur in galactic centers that experienced a tidal disruption event (TDE) a few years earlier. This may be reasonably explained if QPEs are produced when a star orbiting a supermassive black hole passes through an accretion disk formed by the TDE. Based on this scenario, we investigate the expected QPE signatures in the ear…

Evidence for enhanced mass transfer in the disc preceding the transition to the soft state in MAXI J1820 070
Pengcheng Yang, Guobao Zhang, David M. Russell, Mariano M\'endez, M. Cristina Baglio, Diego Altamirano, Yijung Yang, Payaswini Saikia, Kevin Alabarta
https://arxiv.org/abs/2507.00532

Evidence for enhanced mass transfer in the disc preceding the transition to the soft state in MAXI J1820+070
We investigate the 2018-2019 main outburst and the subsequent mini-outbursts of the black hole low-mass X-ray binary MAXI J1820+070 using optical/ultraviolet data from the Las Cumbres Observatory (LCO), the American Association of Variable Star Observers (AAVSO), and $\textit{Swift}$/UVOT, as well as X-ray data from $\textit{Insight}$-HXMT and $\textit{Swift}$/XRT. Given the high-cadence observations, we identify a broad dip-like feature in both the optical and X-ray light curves preceding the …

Elemental Abundances in X-ray Binary Outflows
Noa Keshet, Ehud Behar, Jon M. Miller
https://arxiv.org/abs/2506.19440 https://arxiv.or…

Elemental Abundances in X-ray Binary Outflows
Line resolved X-ray spectra of outflows from X-ray binaries are interesting since they provide quantifiable measures of the accreted material on to the compact object (black hole or neutron star), which can not be observed directly in the accretion disk. One such measurement that has been largely overlooked is that of the elemental abundances, which potentially provide insights into the origin of the ejected material. Using the Chandra/HETG grating spectrometer we measure and present elemental …