GRB 180418A: A Possibly Short Gamma-Ray Burst with a Wide-angle Outflow in a Faint Host Galaxy
GRB 180418A: A Possibly Short Gamma-Ray Burst with a Wide-angle Outflow in a Faint Host Galaxy
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DOI：
10.3847/1538-4357/abee85
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发表时间：
2020-12
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通讯作者：
A. R. Escorial;W. Fong;P. Veres;T. Laskar;A. Lien;K. Paterson;Maura Lally;P. Blanchard;A. Nugent;N. Tanvir;D. Cornish;Edo Berger;Eric Burns;Brad Cenko;B. Cobb;A. Cucchiara;A. Goldstein;R. Margutti;B. Metzger;Peter Milne;A. Levan;M. Nicholl;N. Smith
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作者：
A. R. Escorial;W. Fong;P. Veres;T. Laskar;A. Lien;K. Paterson;Maura Lally;P. Blanchard;A. Nugent;N. Tanvir;D. Cornish;Edo Berger;Eric Burns;Brad Cenko;B. Cobb;A. Cucchiara;A. Goldstein;R. Margutti;B. Metzger;Peter Milne;A. Levan;M. Nicholl;N. Smith
我们给出了由Swift/BAT和Fermi/GBM发现的GRB 180418A余辉和宿主星系的X射线和多波段光学观测。我们对GBM和BAT数据进行了重新分析，分别得出了T90≈2.5 6和1.90 S的瞬发持续时间。模拟了FERMI/GBM星表中的1405次暴(2008年-2014年)，我们得到了≈为60%的GRB180418A是短硬暴的概率。根据SWIFT/XRT和钱德拉观测的结果，X射线余辉在爆发后38.5d被探测到≈，并呈现单次幂规律下降，FX∝t−为0.98.后期的双子座观测揭示了一个微弱的r≈25.69Mag的宿主星系，其角偏移为≈0。16.在可能的红移范围内，我们发现伽马射线暴180418A的X射线余辉光度介于短伽马射线暴和长伽马射线暴之间，在所有有同期数据的时期，伽马射线暴180418A位于离E≈更近的地方，峰值-Eγ，短伽马射线暴的等关联。用标准同步辐射模型对多波长余辉进行了模拟，得到了爆发爆炸特性，得到了θj≳9°~14°的喷流张开角。如果伽玛暴180418A是一个由中子星合并而来的短伽玛暴，那么它拥有最明亮、寿命最长的余辉之一，以及一个极其昏暗的宿主星系。相反，如果该事件是一个起源于大质量恒星坍塌的长伽玛暴，它的余辉亮度是最低的之一，并且就硬度-T 90和E-γ、峰值-Eγ、iso平面而言，它位于一个特殊的空间。
We present X-ray and multiband optical observations of the afterglow and host galaxy of GRB 180418A, discovered by Swift/BAT and Fermi/GBM. We present a reanalysis of the GBM and BAT data deriving durations of the prompt emission of T 90 ≈ 2.56 and 1.90 s, respectively. Modeling the Fermi/GBM catalog of 1405 bursts (2008–2014) in the hardness–T 90 plane, we obtain a probability of ≈60% that GRB 180418A is a short-hard burst. From a combination of Swift/XRT and Chandra observations, the X-ray afterglow is detected to ≈38.5 days after the burst and exhibits a single power-law decline with F X ∝ t −0.98. Late-time Gemini observations reveal a faint r ≈ 25.69 mag host galaxy at an angular offset of ≈0.″16. At the likely redshift range of z ≈ 1–2.25, we find that the X-ray afterglow luminosity of GRB 180418A is intermediate between short and long gamma-ray bursts (GRBs) at all epochs during which there are contemporaneous data and that GRB 180418A lies closer to the E γ,peak–E γ,iso correlation for short GRBs. Modeling the multiwavelength afterglow with the standard synchrotron model, we derive the burst explosion properties and find a jet opening angle of θ j ≳ 9°–14°. If GRB 180418A is a short GRB that originated from a neutron star merger, it has one of the brightest and longest-lived afterglows along with an extremely faint host galaxy. If, instead, the event is a long GRB that originated from a massive star collapse, it has among the lowest-luminosity afterglows and lies in a peculiar space in terms of the hardness–T 90 and E γ,peak–E γ,iso planes.