We study the recent outburst of the black hole candidate EXO 1846-031 which went into an outburst in 2019 after almost 34 years in quiescence. We use archival data from Swift/XRT, MAXI/GSC, NICER/XTI and NuSTAR/FPM satellites/instruments to study the evolution of the spectral and temporal properties of the source during the outburst. Low energy (2-10 keV) X-ray flux of the outburst shows multiple peaks making it a multipeak outburst. Evolving type-C quasi-periodic oscillations (QPOs) are observed in the NICER data in the hard, hard intermediate and soft intermediate states. We use the physical Two Component Advective Flow (TCAF) model to analyze the combined spectra of multiple satellite instruments. According to the TCAF model, the accreting matter is divided into Keplerian and sub-Keplerian parts, and the variation in the observed spectra in different spectral states arises out of the variable contributions of these two types of accreting matter in the total accretion rate. Studying the evolution of the accretion rates and other properties of the accretion flow obtained from the spectral analysis, we show how the multiple peaks in the outburst flux arises out of variable supply of accreting matter from the pile-up radius. We determine the probable mass of the black hole to be $10.4^{+0.1}_{-0.2}~M_\odot$ from the spectral analysis with the TCAF model. We also estimate viscous time scale of the source in this outburst to be $\sim 8$ days from the peak difference of the Keplerian and sub-Keplerian mass accretion rates.
A Multi-Wavelength Picture of the Surprisingly Short 2024/25 Outburst from EXO 0748-676
Durham University（杜伦大学）；McGill University（麦吉尔大学）；University of Warwick（华威大学）；New York University Abu Dhabi（阿布扎比纽约大学）；INAF, Osservatorio Astronomico di Brera（意大利国家天体物理研究所布里拉天文台）；Anton Pannekoek Institute for Astronomy, Universiteit van Amsterdam（阿姆斯特丹大学安东·潘内克天文研究所）；Yale University（耶鲁大学）
AU Microscopii in the FUV: Observations in Quiescence, During Flares, and Implications for AU Mic b and c
来自年轻恒星的高能X射线和紫外线辐射影响行星大气化学和质量损失。活跃的$\sim 22$ Myr M矮星AU Mic拥有两颗系外行星，它们围绕着它的碎片盘内部运行。因此，该系统提供了一个独特的机会，以量化恒星XUV辐射对行星大气层的影响，作为年龄和轨道分离的函数。在本文中，我们提出了超过5个小时的远紫外（FUV）的观测AU Mic采取的宇宙起源光谱仪（COS; 1070-1360埃）的哈勃太空望远镜（HST）。我们在HST/COS FUV光谱中提供了$120$发射特征的逐项说明，并量化了从$10^4-10^7$ K.我们在FUV白光曲线上探测到了13个耀斑，能量从$10^{29} - 10^{31}$尔格到2000尔格不等。这些耀斑中的大部分能量都是从色球层和日冕之间的过渡区释放出来的。在连续波长$λ< 1100$埃处，每个耀斑的通量增加100 $\times$，这可能是由热韧致辐射引起的。我们计算出AU Mic b的基线大气质量损失率为$\sim 10^8$ g s $^{-1}$，尽管在$L_\textrm{flare} \simeq 10^{33}$ erg s $^{-1}$的耀斑期间，该速率可以高达$\sim 10^{14}$ g s $^{-1}$。最后，我们建立了一个新的泛色光谱的AU Mic c和激励未来的JWST观测这些行星的传输光谱AU Mic b和c。
Probing accretion dynamics and spin evolution in the X-ray pulsar RX J0520.5-6932 during its 2024 Outburst
Inter-University Centre for Astronomy and Astrophysics (IUCAA)（大学间天文学与天体物理学中心）；Raman Research Institute（拉曼研究所）；Indian Institute of Science Education and Research (IISER) Mohali（印度科学教育与研究学院穆扎法尔纳加尔分校）；School of Physics & Astronomy, University of Southampton（南安普顿大学物理与天文学院）；Indian Institute of Astrophysics（印度天体物理研究所）；Universitá degli Studi di Cagliari, Dipartimento di Fisica（卡利亚里大学物理系）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理研究所）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）
The compact jets of the black hole X-ray binary Swift J1753.5-0127 during its 2023-2024 outburst
Université Paris Cité（巴黎西岱大学）；Université Paris-Saclay（巴黎萨克雷大学）；CEA（法国原子能和替代能源委员会）；CNRS（法国国家科学研究中心）；AIM（天体物理与分子研究所）；McGill University（麦吉尔大学）；Trottier Space Institute, McGill University（麦吉尔大学特罗蒂尔太空研究所）；New York University（纽约大学）；INAF–Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；INAF–Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Julius-Maximilians-Universität Würzburg（维尔茨堡朱利叶斯-马克西米利安大学）；Yale University（耶鲁大学）；University of Oxford（牛津大学）；University of Cape Town（开普敦大学）
