A Study on the Hysteresis Effect and Spectral Evolution in the Mini-Outbursts of Black Hole X-Ray Binary XTE J1550-564

Frontiers in Astronomy and Space Sciences

Zi-Yi You¹  Chang Liu²  Qi-Jun Zhi²  Kang Ge²  Xiang Liu³  Ai-Jun Dong⁴ 

[1] School of Physics and Electronic Science, Guizhou Normal University, Guiyang, China;School of Physics and Electronic Science, Guizhou Normal University, Guiyang, China;Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing, Guizhou Normal University, Guiyang, China;Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, China;Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, China;School of Physics and Electronic Science, Guizhou Normal University, Guiyang, China;Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing, Guizhou Normal University, Guiyang, China;

关键词: accretion;    accretion discs;    stars: black holes;    X-ray binaries;    X-rays: individual: XTE J1550-564;   

DOI  :  10.3389/fspas.2021.651661

来源: Frontiers

【 摘 要 】

One normal outburst and three mini-outbursts have been detected by Rossi X-ray Timing Explorer satellite after 2000 in the well-known black hole X-ray binary XTE J1550-564. In this work, we explore the hysteresis effect of the four outbursts, which is a phenomenon that a similar spectral state transition occurs at different luminosity in an outburst of black hole X-ray binary. A q-like track was found in the hardness-intensity diagram of the normal outburst in 2000 but not in the three mini-outbursts that only occur in the Low/Hard state. The results demonstrate that the hysteresis effect is not apparent in the three mini-outbursts and the X-ray spectra are harder than that of the normal outburst at the same photon count rate. Furthermore, the results of the correlation analysis show that the Γ − F2−10keV correlation of mini-outburst maintain negative in the Low/Hard state with the harder spectra than that of the normal outburst at the same X-ray flux. The X-ray spectral evolution can be well-explained by the state-transition model from the Shakura–Sunyaev disk to the advection-dominated accretion flow, which implies that the three mini-outbursts of XTE J1550-564 might originate from a smaller discrete accretion event.

【 授权许可】

CC BY