ASASSN-18ey: The Rise of a New Black Hole X-Ray Binary
ASASSN-18ey: The Rise of a New Black Hole X-Ray Binary
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DOI：
10.3847/2041-8213/aae88a
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
M. Tucker;B. Shappee;T. Holoien;K. Auchettl;K. Auchettl;J. Strader;K. Stanek;C. Kochanek;
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文献类型：
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作者：
M. Tucker;B. Shappee;T. Holoien;K. Auchettl;K. Auchettl;J. Strader;K. Stanek;C. Kochanek;
我们介绍了ASASSN-18ey(MAXI J1820+070)的发现，这是一颗新的黑洞低质量X射线双星(LMXB)，它是由全天自动探测超新星(ASAS-SN)发现的。在ASAS-SN发现ASASSN-18ey为光学瞬变后一周，它被MAXI/GCS检测为X射线瞬变。在这里，我们分析了ASAS-SN和小行星地面撞击末次警报系统爆发前的光学光曲线，找到了爆发前几年内在变异性的证据。虽然没有像在其他几个系统中看到的那样导致暴发的长期上升，但光学暴发的开始时间比X射线早7.20±0.97d。我们分析了ASASSN-18ey从极大值前到极大值后100天的光谱演化。ASASSN-18EY的光谱表现出宽的、不对称的双峰H-α发射。波文混合星(λ≈4650？)在后极大值光谱中显示出高度可变的双峰轮廓，很可能是由低质量X射线双星的典型吸积盘对伴星的照射引起的。ASASSN-18ey的光学和X射线发光度与黑洞低质量X射线双星在爆发和静止时都是一致的。
We present the discovery of ASASSN-18ey (MAXI J1820+070), a new black hole low-mass X-ray binary (LMXB) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). A week after ASAS-SN discovered ASASSN-18ey as an optical transient, it was detected as an X-ray transient by MAXI/GCS. Here, we analyze ASAS-SN and Asteroid Terrestrial-impact Last Alert System pre-outburst optical light curves, finding evidence of intrinsic variability for several years prior to the outburst. While there was no long-term rise leading to the outburst, as has been seen in several other systems, the start of the outburst in the optical preceded that in the X-rays by 7.20 ± 0.97 days. We analyze the spectroscopic evolution of ASASSN-18ey from pre-maximum to >100 days post-maximum. The spectra of ASASSN-18ey exhibit broad, asymmetric, double-peaked Hα emission. The Bowen blend (λ ≈ 4650 Å) in the post-maximum spectra shows highly variable double-peaked profiles, likely arising from irradiation of the companion by the accretion disk, typical of low-mass X-ray binaries. The optical and X-ray luminosities of ASASSN-18ey are consistent with black hole low-mass X-ray binaries, both in outburst and quiescence.