标题： X射线能谱形状在变化型赛弗特星系SDSSJ155258+273728中的变化 显示英文标题

标题： X-ray spectral shape variations in changing-look Seyfert galaxy SDSSJ155258+273728

摘要： 我们分析了“变化外观”塞弗特星系\sdssj 15 在$z\simeq0.086$的X射线、光学和中红外数据。在十年期间（2009 - 2018），其宽H$\alpha$线强度增加了$\sim$4倍。同时，2014年由\chandra 观测到的X射线辐射比2010年由{\it 般若}观测到的亮度高五倍，相应的V波段、中红外W1波段亮度分别增加了$\sim$0.18, 0.32星等。此外，X射线中的吸收是中等且稳定的，即 ${\rm N_{H}}\sim 10^{21} {\rm cm^{-2}}$，但2014年\chandra 亮态的X射线谱变得更硬（即光子指数$\Gamma = 1.52^{+0.06}_{-0.06}$），比2010年\suzaku 低态的X射线谱更硬（$\Gamma=2.03^{+0.22}_{-0.21}$）。 当爱丁顿比率低于百分之几时，\sdssj 15吸积盘的内部区域可能是一个热吸积流。 我们从文献中整理了“改变外观”活动星系核的X射线数据，并发现它们通常遵循活动星系核中已建立的“V”形相关性，即在临界转折光度以上，X射线谱随着光度增加而变软，而在该光度以下，趋势相反，表现为“越亮越硬”。 这直接证明了CL-AGNs不仅在光学光谱类型上有显著变化，而且在X射线光谱形状上也有显著变化。 CL-AGNs和黑洞X射线双星在X射线光谱演化方面的相似性表明，观测到的CL-AGNs现象可能与吸积物理中的状态转换有关。 显示英文摘要

摘要： We analyze the X-ray, optical, and mid-infrared data of a "changing-look" Seyfert galaxy \sdssj15 at $z\simeq0.086$. Over a period of one decade (2009 - 2018), its broad H$\alpha$ line intensity increased by a factor of $\sim$4. Meanwhile, the X-ray emission in 2014 as observed by \chandra\ was about five times brighter than that in 2010 by {\it Suzaku}, and the corresponding emissions in V-band, mid-infrared W1 band brighten by $\sim$ 0.18, 0.32 mag, respectively. Moreover, the absorption in X-rays is moderate and stable, i.e. ${\rm N_{H}}\sim 10^{21} {\rm cm^{-2}}$, but the X-ray spectrum becomes harder in the 2014 \chandra\ bright state (i.e. photon index $\Gamma = 1.52^{+0.06}_{-0.06}$) than that of the 2010 \suzaku\ low state ($\Gamma=2.03^{+0.22}_{-0.21}$). With an Eddington ratio being lower than a few percent, the inner region of the accretion disk in \sdssj15\ is likely a hot accretion flow. We then compile from literature the X-ray data of "changing-look" AGNs, and find that they generally follow the well-established "V"-shaped correlation in AGNs, that is, above a critical turn-over luminosity the X-ray spectra soften with the increasing luminosity, and below that luminosity the trend is reversed in a way of "harder when brighter". This presents a direct evidence that CL-AGNs have distinctive changes in not only the optical spectral type, but also the X-ray spectral shape. The similarity in the X-ray spectral evolution between CL-AGNs and black hole X-ray binaries indicates that the observed CL-AGNs phenomena may relate to the state transition in accretion physics.