A mildly relativistic outflow from the energetic, fast-rising blue optical transient CSS161010 in a dwarf galaxy
D. L. Coppejans, R. Margutti, G. Terreran, A. J. Nayana, E. R. Coughlin, T. Laskar, K. D. Alexander, M. Bietenholz, D. Caprioli, P. Chandra, M. Drout, D. Freder… 展开作者
D. L. Coppejans, R. Margutti, G. Terreran, A. J. Nayana, E. R. Coughlin, T. Laskar, K. D. Alexander, M. Bietenholz, D. Caprioli, P. Chandra, M. Drout, D. Frederiks, C. Frohmaier, K. Hurley, C. S. Kochanek, M. MacLeod, A. Meisner, P. E. Nugent, A. Ridnaia, D. J. Sand, D. Svinkin, C. Ward, S. Yang, A. Baldeschi, I. V. Chilingarian, Y. Dong, C. Esquivia, W. Fong, C. Guidorzi, P. Lundqvist, D. Milisavljevic, K. Paterson, D. E. Reichart, B. Shappee, M. C. Stroh, S. Valenti, A. Zauderer, B. Zhang
We present X-ray and radio observations of the Fast Blue Optical Transient (FBOT) CRTS-CSS161010 J045834-081803 (CSS161010 hereafter) at t=69-531 days. CSS161010 shows luminous X-ray ($L_x\sim5\times 10^{39}\,\rm{erg\,s^{-1}}$) and radio ($L_ν\sim10^{29}\,\rm{erg\,s^{-1}Hz^{-1}}$) emission. The radio emission peaked at ~100 days post transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blastwave. CSS161010 launched a mildly relativistic outflow with velocity $Γβc\ge0.55c$ at ~100 days. This is faster than the non-relativistic AT2018cow ($Γβc\sim0.1c$) and closer to ZTF18abvkwla ($Γβc\ge0.3c$ at 63 days). The inferred initial kinetic energy of CSS161010 ($E_k\gtrsim10^{51}$ erg) is comparable to that of long Gamma Ray Bursts (GRBs), but the ejecta mass that is coupled to the mildly relativistic outflow is significantly larger ($\sim0.01-0.1\,\rm{M_{\odot}}$). This is consistent with the lack of observed gamma-rays. The luminous X-rays were produced by a different emission component to the synchrotron radio emission. CSS161010 is located at ~150 Mpc in a dwarf galaxy with stellar mass $M_{*}\sim10^{7}\,\rm{M_{\odot}}$ and specific star formation rate $sSFR\sim 0.3\,\rm{Gyr^{-1}}$. This mass is among the lowest inferred for host-galaxies of explosive transients from massive stars. Our observations of CSS161010 are consistent with an engine-driven aspherical explosion from a rare evolutionary path of a H-rich stellar progenitor, but we cannot rule out a stellar tidal disruption event on a centrally-located intermediate mass black hole. Regardless of the physical mechanism, CSS161010 establishes the existence of a new class of rare (rate $<0.4\%$ of the local core-collapse supernova rate) H-rich transients that can launch mildly relativistic outflows.
HST unveils a compact mildly relativistic Broad Line Region in the candidate true type 2 NGC 3147
NGC 3147被认为是真正的第2型活动星系核的最佳例子：一个无遮蔽的活动星系核，基于未被吸收的致密X射线连续谱，缺乏宽线区（BLR）。然而，NGC 3147非常低的光度意味着一个紧凑的BLR，它产生非常宽的线条，很难在占主导地位的背景星系中检测到。窄缝（0.1“x0.1”）的HST光谱允许我们排除大部分的宿主星系的光，并揭示了一个H $α$线与一个非常广泛的基础（FWZI $\sim27\,000$ km s $^{-1}$）。线剖面显示了一个陡峭的蓝翼和一个扩展的红翼，这与一个温和的相对论性薄吸积盘线剖面的特征相匹配。它确实很好地拟合了一个在$i\sim23^\circ$上的薄盘上的近似面，其内半径为$77\pm15$ r $_g$，这与根据$R_{\rm BLR} \sim L^{1/2}$关系对$62^{+18}_{-14}$ r $_g$的预测相匹配。这一结果对真正的2型活动星系核的存在提出了质疑。此外，薄盘，它在$L/L_{\rm Edd}\sim10^{-4}$系统中延伸到100 r $_g$以下的检测，与当前在极低吸积速率下的吸积流配置的观点相矛盾。
AT2021yky: A Fast-Rising Optical Transient with Evolving Broad Hydrogen Emission Consistent with an Ambiguous Nuclear Transient
The Ohio State University（俄亥俄州立大学）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Institute for Astronomy, University of Hawai‘i at Manoa（夏威夷大学马诺阿分校天体物理研究所）；University of Michigan（密歇根大学）；The University of Melbourne（墨尔本大学）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；University of Cambridge（剑桥大学）；Space Telescope Science Institute（太空望远镜科学研究所）
Light-curve Modelling for The Initial Rising Phase of Rapidly-evolving Transients Powered by Continuous Outflow
风驱动模式是一个新的框架，模拟观测特性的瞬变动力来自一个中央系统的连续流出。虽然它已被应用于快蓝光学瞬变（FBOTs），但由于稳态假设，其适用性仅限于峰后行为;非稳态物理，例如，扩大外流，是重要的模拟初始上升阶段。在本文中，我们建立了一个时间相关的风驱动模式，它可以考虑到扩大流出和流出率的时间演变。我们将该模型应用于一个样本的观察良好的FBOTs。FBOT需要高流出速率（$\sim 30$ M $_{\odot}$ yr $^{-1}$）和快速度（$\sim 0.2-0.3c$），典型的喷出物质量和能量预算分别为$\sim 0.2$ M $_{\odot}$和$\sim 10^{52}$ erg。能量外流支持了这样一种观点，即FBOT的中心引擎可能与相对论物体有关，例如，一个黑洞光球的初始温度是$10^{5-6}$ K，这表明FBOTs将显示类似于超新星激波爆发的紫外线或X射线闪光。我们讨论了未来的前景调查和后续观测的FBOTs在紫外波段。FBOT在紫外波段比在光学波段更亮，并且时间尺度比光学波长长一点。我们认为，具有宽视场的紫外望远镜可以在发现FBOTs和表征其性质方面发挥关键作用。
Radio Emission from Fast Blue Optical Transients Powered by Trans-relativistic Shocks in Confined Circumstellar Material
Central China Normal University（华中师范大学）；Institute of Astrophysics, Central China Normal University（华中师范大学天体物理研究所）；Laboratory for Compact Object Astrophysics and Astronomical Technology, Central China Normal University（华中师范大学致密天体天文学与技术实验室）；Education Research and Application Center, National Astronomical Data Center（国家天文台教育研究与应用中心）
Evidence for Late-stage Eruptive Mass-loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient
Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope. I. Correlations between Flux, Color, and Polarization
Indication of the Less-ionized Clumpy Ultra-Fast Outflows in Seyfert Galaxies
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency（宇宙科学研究所，日本宇宙航空研究开发机构）；Department of Astronomy, Graduate School of Science, The University of Tokyo（东京大学理学研究科天文学专攻）；Mercari；Science education research unit, University of Teacher Education Fukuoka（福冈教育大学科学教育研究单位）
