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Arxiv_Daily_Notice/2026-05-08-Arxiv-Daily-Paper.md

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+# Showing new listings for Friday, 8 May 2026
+Auto update Star Formation & Molecular Cloud papers at about 2:30am UTC (10:30am Beijing time) every weekday.
+
+
+阅读 `Usage.md`了解如何使用此repo实现个性化的Arxiv论文推送
+
+See `Usage.md` for instructions on how to personalize the repo. 
+
+
+Keyword list: ['star formation', 'star-forming', 'molecular cloud', 'interstellar medium', 'cloud', 'clump', 'core', 'filament', 'atomic gas', 'N-PDF']
+
+
+Excluded: ['galaxies', 'galaxy cluster', ' AGN ', 'standard candle', 'X-ray binar', 'solar corona']
+
+
+### Today: 9papers 
+#### On the Origin of Mass Ejection in Failed Supernovae
+ - **Authors:** Daniel A. Paradiso, Sarah Vallejo, Eric R. Coughlin
+ - **Subjects:** Subjects:
+High Energy Astrophysical Phenomena (astro-ph.HE)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05289
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05289
+
+ - **Abstract**
+ Some high-mass stars likely end their lives in underluminous implosions that leave behind a black hole, known as failed supernovae (FSNe). However, neutrinos radiated during proto-neutron star formation generate a weak (Mach $\gtrsim 1$) shockwave in the outer layers of the star, which produces a unique transient as it breaks out of the dying star and signals its imminent disappearance. It was recently shown that there are two self-similar solutions that describe the propagation of this weak shockwave, and these solutions simultaneously contain outward-moving ejecta and fallback accretion onto the black hole. Here we show that the larger Mach number solutions are unstable, such that the Mach number of the shock grows with time $t$ and deviates from the self-similar prediction as $\propto t^{\alpha}$, with $\alpha \lesssim 0.1$, whereas the smaller Mach number solutions are stable. We also show that, above a critical mass loss that is readily achievable in core-collapse supernovae, the shock asymptotically strengthens and approaches the strong limit. Our results imply that it is the mass lost to neutrinos \textit{relative} to the mass enclosed by the shockwave, as well as the stellar density gradient where the shock forms, that primarily dictate its strength and the amount of material it ejects. These criteria explain why red supergiants, which have relative mass losses well in excess of the critical value at the time of shock formation, more readily eject material and create more luminous explosions compared to more compact progenitors.
+#### The Impact of Radiation Environment on the Evolution and Fragmentation of Protostellar Discs
+ - **Authors:** Matt T. Cusack, Paul C. Clark, Ken Rice, Simon C. O. Glover, Ralf S. Klessen, Anthony P. Whitworth, Felix D. Priestley, Ana Duarte-Cabral
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05377
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05377
+
+ - **Abstract**
+ We present high-resolution zoom-in simulations of molecular clouds exposed to an interstellar radiation field and cosmic ray ionisation rate up to 1000 times stronger than that of the solar neighbourhood. We detail the evolution of the accretion discs that form around the first protostar in each simulation, for a total of 7 discs, for up to 100 kyr. The use of a zoom-in procedure allows for the au-scale discs to be well resolved (with resolution < 0.25 au) whilst retaining the structure of the wider parsec-scale molecular cloud. We find that discs exposed to a stronger radiation field tend to be more massive, hotter and denser. Similarly, their host stars grow to become more massive as a result of accreting more rapidly from their surroundings. All the discs show evidence of recurrent instability during the simulations, but only some of them fragment. We investigate whether stability metrics, such as the Toomre $Q$, $\alpha$ viscosity, and $\beta$ cooling parameter, can predict fragmentation by calculating them just before the discs fragment. We find that the metrics are generally unable to do so, as the discs appear stable even up to a few hundred years before fragmenting. In solar-like environments fragments are typically of planetary mass and often migrate to the centre of the disc, whereas fragments in a high-radiation environment are massive ($\rm > 0.1 \, M_\odot$) and fully disrupt/accrete from the progenitor disc. We conclude that the evolution and properties of circumstellar discs depend on both their radiation and physical environment.
+#### How do the LIGO-Virgo-KAGRA's Heavy Black Holes Form? No evidence for core-collapse Intermediate-mass black holes in GWTC-4
+ - **Authors:** Fan-Xiao-Yu Xia, Yuan-Zhu Wang, Ying Qin
+ - **Subjects:** Subjects:
+High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05563
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05563
+
+ - **Abstract**
+ We investigate the population properties of binary black holes (BBHs) from the LIGO-Virgo-KAGRA collaboration, focusing especially on those in the high-mass range, using the newly released GWTC-4 catalog. For the first time, we search for a subpopulation of low-spin intermediate-mass black holes (IMBHs) that would indicate formation via stellar core collapse. With the currently available catalog, we find no evidence for such a subpopulation, and set a 90\% upper limit on the merger rate of collapse-formed IMBHs at $0.077~\mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$. The mass distribution of low-spin (stellar-origin) black holes truncates at $65^{+23}_{-22}\,M_\odot$, consistent with the lower edge of the pair-instability mass gap (PIMG), although we cannot directly determine its upper boundary from current data. Informed by stellar evolution theory, we estimate the upper edge of the PIMG to be $150\pm24\,M_\odot$. We find that the observed IMBHs belong to a high-spin subpopulation, consistent with formation through successive hierarchical mergers.
+#### Helium emission from Balmer-dominated shocks in Type Ia supernova remnants provides constraints to their progenitor systems
+ - **Authors:** Priyam Das, Ivo Rolf Seitenzahl, Parviz Ghavamian, Ashley Jade Ruiter, J. Martin Laming, Simon J. Murphy, Cillian O'Donnel
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Atomic Physics (physics.atom-ph)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05661
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05661
+
+ - **Abstract**
+ Balmer-dominated shocks in Type Ia supernova remnants offer powerful probes into collisionless shock physics and hints towards supernova progenitor environments. Prior studies focused on the hydrogen Balmer lines, which manifest as a superposition of broad and narrow emission lines. Using integral-field spectroscopy with MUSE, we discovered broad and narrow helium emission lines from Balmer-dominated filaments of three Type Ia supernovae remnants in the Large Magellanic Cloud: SNR 0509-67.5, SNR 0519-69.0 and N103B. We detect broad and narrow He~\textsc{i} 5876~Å~,7065~Å emission in SNR 0519 and N103B and He \textsc{ii} 8236~Å in SNR 0519. In SNR 0509 we detect narrow He~\textsc{i} 5015~Å, 6678~Å, 7065~Å and 7281~Å, with only 7065~Å~ exhibiting a broad component. The detection of narrow He\,\textsc{ii} challenges existing shock models, where such emission is not expected, and may indicate either incomplete ion-ion equilibration behind the shock or an origin in shock precursors. For SNR 0509 and N103B, the neutral He/H line ratios indicate enhanced helium abundances, whereas SNR 0519 is consistent with the primordial He/H value. We therefore propose helium emission in Balmer-dominated shocks as a new diagnostic of shock physics and Type Ia supernova circumstellar environments. Although our modeling is primarily a proof of concept, it demonstrates the possibility to infer the total He-to-H abundance ratio, with dominant uncertainties arising from the assumed initial ionization fractions. Despite the uncertainties, we demonstrate that narrow helium lines can serve as effective probes of circumstellar conditions and progenitor evolution when analysed alongside reliable constraints on the preshock neutral H/He abundance ratio.
+#### Detection of an Extended Ly$α$ Halo around a $\textit{z}=6.64$ Broad Absorption Line Quasar with the Keck Cosmic Web Imager
+ - **Authors:** Raymond P. Remigio, Aaron J. Barth, Feige Wang, Jinyi Yang, Joseph F. Hennawi, Ryan J. Cooke, Eduardo Banados, Xiaohui Fan, Emanuele Paolo Farina
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05673
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05673
+
+ - **Abstract**
+ We present the first results from a program searching for extended Ly$\alpha$ halos around high redshift ($ z \gtrsim 6.5$) quasars using the red channel of the Keck Cosmic Web Imager (KCWI). Our observations reveal a Ly$\alpha$ halo extending to $\simeq11$ pkpc around the $z=6.64$ broad absorption line quasar J0910$-$0414. The Ly$\alpha$ velocity field displays a rotation-like gradient, and the gas velocity dispersion is consistent with gravitationally dominated motion ($\sigma_{\mathrm{Ly\alpha}}<300$ km s$^{-1}$). Comparison with the $[\mathrm{C\;II}]$ kinematics of the host galaxy core from ALMA observations shows that the Ly$\alpha$-emitting gas extends over a much larger region, shows distinct kinematics, and has a smaller velocity dispersion ($\sigma_{\mathrm{Ly\alpha}} \simeq 0.6\sigma_{\mathrm{[C\;II]}}$). The Ly$\alpha$ spectral region of the quasar is largely obscured by a deep $\mathrm{N\;V}$ absorption trough, and as a result, roughly $55\%$ of the total Ly$\alpha$ flux is from the extended halo. These observations demonstrate the potential of KCWI for probing the cool gas reservoir that fuels the growth of quasars and their hosts in the epoch of reionization.
+#### IY Lyr: A Thick-Disk first-overtone RR Lyrae Star with a Possible Neutron Star Companion
+ - **Authors:** Linjia Li, Shengbang Qian, Ildar Asfandiyarov, Azizbek Matekov, Liying Zhu, Boonrucksar Soonthornthum, Evelina Gaynullina, Alina Khalikova, Jiajia He, Fangbin Meng, Huiting Zhang, Jiangjiao Wang, Xiangdong Shi
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05708
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05708
+
+ - **Abstract**
+ IY Lyr, historically misclassified as an eclipsing binary, is now established as a first-overtone RR Lyrae star (RRc star). Using multi-band photometry (ASAS-SN, ZTF, TESS, and our BVRI data), LAMOST spectroscopy, and Gaia astrometry, we investigate its pulsation, binarity, and Galactic population. From O-C analysis, we detect a long-term period decrease and a light-travel time effect with an orbital period of 3.94 years, eccentricity of 0.46, and a mass function of 0.65 M$_{\odot}$. The companion is independently confirmed by radial velocity residuals and Gaia proper motions. Combined constraints yield an orbital inclination of 94.8$^{\circ}$ and a companion mass of 1.37 M$_{\odot}$. Chemical abundances ([Fe/H] $\simeq$ -1.0, [$\alpha$/Fe] $\simeq$ +0.27, Xiang et al. 2019) and dynamics ($L_{\rm z}$ $\simeq$ 1250 kpc km s$^{-1}$, $Z_{\rm max}$ $\simeq$ 1.31 kpc) identify IY Lyr as an old, high-$\alpha$, thick-disk star. The companion mass lies at the peak of the neutron star mass distribution, and the system's age excludes a main-sequence star; we conclude the companion is most likely a typical neutron star, although a massive white dwarf near the Chandrasekhar limit cannot be ruled out. IY Lyr is among the few RRc binaries with a compact companion verified by multiple methods, and it has important implications for thick-disk binary evolution and neutron star formation.
+#### ATOMIUM: Inner circumstellar envelopes of oxygen-rich AGB stars as revealed by highly excited SiO lines
+ - **Authors:** B. Pimpanuwat, S. Etoka, M. D. Gray, A. M. S. Richards, A. Baudry, F. Herpin, T. Danilovich, L. Decin, M. O. Lewis, I. El Mellah, C. A. Gottlieb, Y. Mori, H. S. P. Müller, R. Sahai, K. T. Wong, J. A. Yates, A. Zijlstra
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05760
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05760
+
+ - **Abstract**
+ Silicon monoxide (SiO) traces the physical conditions and dynamics in the circumstellar envelopes (CSEs) of AGB stars. We present high-resolution ALMA Band 6 observations of highly excited SiO emission in 14 oxygen-rich AGB stars. We cover transitions from v = 0 to v = 8, including first detections of 28SiO v = 3, 4, 8, J = 6-5, 29SiO v = 6, J = 6-5, and 30SiO v = 4, 5, J = 6-5, some of which are masers. The v = 8 transition is the highest v-state observed in an AGB star yet. Masers in v = 0 are detected clearly in V PsA and IRC+10011 and tentatively in T Mic. R Hya exhibits the richest SiO spectrum. SiO J = 6-5 absorption is seen in R Aql, R Hya, S Pav, and T Mic, with features indicative of both infalls and outflows, and tentative detection of 28SiO v = 8, J = 6-5 absorption is found towards S Pav and R Aql. Highly excited SiO emission is often distributed in arcs or clumps with velocity gradients; components in R Hya and U Her align with predicted shock fronts. Detection rates show no significant difference between low and high mass-loss rate stars, although line overlap may affect some intensities. Maser detections appear uncorrelated with pulsation period or phase. The radius enclosing 90 per cent of compact SiO emission shows a tentative correlation with mass-loss rate. These results highlight the role of mass loss and CSE geometry in shaping high-excitation SiO emission.
+#### Modeling of Coronal Mass Ejection Originated from a Sheared Arcade of Realistic Active-Region Scale and Its Propagation in the Heliosphere: Methodology
+ - **Authors:** Chaowei Jiang, Xueshang Feng, Liping Yang, Huichao Li, Jinhan Guo, Pingbing Zuo, Yi Wang
+ - **Subjects:** Subjects:
+Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.05883
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.05883
+
+ - **Abstract**
+ Simulating coronal mass ejections (CMEs) from their origin in active regions (ARs) to their propagation to Earth remains challenging, particularly when aiming to resolve AR scales and employ realistic magnetic field strengths without compromising computational efficiency. Here we present a methodology for end-to-end CME modeling that addresses these challenges. Three nested magnetohydrodynamic simulations are coupled to jointly cover the heliosphere from solar surface to beyond $1.5$ au. A block-structured adaptive mesh refinement scheme is employed to achieve $\sim 700$ km resolution in the low corona, allowing AR scales to be resolved while maintaining the total grid count below $10^8$ across the entire computational domain. A semi-relativistic Boris correction combined with a relativistic mass-density factor is used to handle magnetic field strengths up to $10^3$ G without prohibitively small time steps. Using this model, we simulate the emergence of a bipolar AR into the corona, the initiation of a CME by shearing of the AR core field and the subsequent evolution. Our simulation captures its pre-eruption energy buildup, triggering by magnetic reconnection, rapid acceleration, and propagation to 1 au and beyond. The simulated CME exhibits a three-part structure in synthetic coronagraph images and a torus-shaped flux rope in the heliosphere, with synthetic in-situ observations showing shock formation, density compression, and a prolonged southward $B_z$ component at 1 au. The entire simulation requires about one day on a moderately sized cluster (e.g., $600$ processors), while the simulated CME takes three days to arrive at $1$ au, offering a lead time of two days if used for forecasting.
+#### Phase-Space Crystallization in Galactic Globular Clusters: A Gaia-Based Metric and Implications for Technosignature Searches
+ - **Authors:** Bo-Lun Huang, Zhen-Zhao Tao, Tong-Jie Zhang
+ - **Subjects:** Subjects:
+Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
+ - **Arxiv link:** https://arxiv.org/abs/2605.06072
+
+ - **Pdf link:** https://arxiv.org/pdf/2605.06072
+
+ - **Abstract**
+ We develop a model-independent framework to quantify phase-space "crystallization", the degree of ordered radial and kinematic substructure, in 79 Galactic globular clusters using the Gaia EDR3-based membership catalogue of E. Vasiliev & H. Baumgardt (2021a). We construct a scalar crystallization index, C_index, by combining a radial inhomogeneity metric (z_rad) and a local, cluster-centric tangential-velocity metric (z_vel) standardized against empirical nulls. The population distribution is strongly non-Gaussian: most clusters are consistent with smooth, equilibrium expectations, while a small high-C tail (C_index >= 2) identifies dynamically complex systems, including NGC 5139 (\omega Cen) and NGC 104 (47 Tuc). Correlation and fixed-N tests show that sample size affects detectability, but does not by itself explain all high-rank objects. Through synthetic injection tests in dynamically "quiet" control clusters, we demonstrate sensitivity to ultra-cold, shell-confined kinematic components, ruling out single-shell structures comprising more than a few to ~ 10-20% of core stars in the best-sampled control clusters. We find no evidence, within the sensitivity of the adopted diagnostics, for phase-space structures that require explanations beyond known dynamical processes. However, C_index provides a useful tool for ranking clusters by dynamical extremeness, serving both as a diagnostic for internal complexity and as a quantitative metric for prioritizing follow-up dynamical or technosignature-oriented observations.
+
+
+by olozhika (Xing Yuchen). 
+
+
+2026-05-08