The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow
The tidal disruption event AT2017eqx: spectroscopic evolution from hydrogen rich to poor suggests an atmosphere and outflow
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DOI：
10.1093/mnras/stz1837
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发表时间：
2019-04
影响因子：
4.8
通讯作者：
M. Nicholl;M. Nicholl;P. Blanchard;E. Berger;S. Gomez;R. Margutti;K. Alexander;J. Guillochon;J. Leja;R. Chornock;B. Snios;K. Auchettl;K. Auchettl;A. Bruce;P. Challis;D. D’Orazio;M. Drout;M. Drout;T. Eftekhari;R. Foley;O. Graur;O. Graur;O. Graur;C. Kilpatrick;A. Lawrence;A. Piro;C. Rojas-Bravo;N. Ross;P. Short;S. Smartt;K. Smith;B. Stalder
中科院分区：
文献类型：
--
作者：
M. Nicholl;M. Nicholl;P. Blanchard;E. Berger;S. Gomez;R. Margutti;K. Alexander;J. Guillochon;J. Leja;R. Chornock;B. Snios;K. Auchettl;K. Auchettl;A. Bruce;P. Challis;D. D’Orazio;M. Drout;M. Drout;T. Eftekhari;R. Foley;O. Graur;O. Graur;O. Graur;C. Kilpatrick;A. Lawrence;A. Piro;C. Rojas-Bravo;N. Ross;P. Short;S. Smartt;K. Smith;B. Stalder
本文介绍并分析了由泛星和地球物理研究所发现的一个新的潮汐扰动事件--AT2017eqx，红移z=0.1089。瞬变的位置与其所在星系核的位置一致；光谱显示持续的黑体温度T≳20000K，有广泛的H I和He II发射；它的峰值出现在黑体光度L≈1044erg S−1。这些谱线最初以零速度为中心，但到100d，H I线消失，而He II蓝移了≳5000 km S−1。早期和晚期的形态都在其他TDEs中看到过，但它们之间的完全跃迁是前所未有的。这种演变可以通过将正在缓慢收缩的延展大气和极地方向的风在后期变得可见来解释。我们的观测证实，缺乏氢的TDE光谱并不意味着有一颗剥离的恒星，而所提出的模型表明，TDEs中的大部分多样性可能是由于观察者的视角所致。对光曲线的模拟表明，AT2017eqx是由一颗太阳质量的恒星被∼106.3 M⊙的黑洞完全分裂而产生的。宿主是另一个巴尔默强吸收星系，尽管比大多数TDE宿主更微弱，中心集中度也更低。射电极限排除了相对论喷流，而500d的X射线极限在这个阶段是TDE最深的。
We present and analyse a new tidal disruption event (TDE), AT2017eqx at redshift z = 0.1089, discovered by Pan-STARRS and ATLAS. The position of the transient is consistent with the nucleus of its host galaxy; the spectrum shows a persistent blackbody temperature T ≳ 20 000 K with broad H i and He ii emission; and it peaks at a blackbody luminosity of L ≈ 1044 erg s−1. The lines are initially centred at zero velocity, but by 100 d, the H i lines disappear while the He ii develops a blueshift of ≳ 5000 km s−1. Both the early- and late-time morphologies have been seen in other TDEs, but the complete transition between them is unprecedented. The evolution can be explained by combining an extended atmosphere, undergoing slow contraction, with a wind in the polar direction becoming visible at late times. Our observations confirm that a lack of hydrogen a TDE spectrum does not indicate a stripped star, while the proposed model implies that much of the diversity in TDEs may be due to the observer viewing angle. Modelling the light curve suggests AT2017eqx resulted from the complete disruption of a solar-mass star by a black hole of ∼106.3 M⊙. The host is another Balmer-strong absorption galaxy, though fainter and less centrally concentrated than most TDE hosts. Radio limits rule out a relativistic jet, while X-ray limits at 500 d are among the deepest for a TDE at this phase.