奇异吸积态的微类星体——M81 ULS1

The strange accretion state in the microquasar M81 ULS1

微类星体拥有与类星体相似的相对论喷流现象,如果喷流的物质为重子,则在光谱中表现为红移和蓝移的发射线。经典的理论和以往的观测表明,对于辐射出超软X射线的天体,相对论喷流是无法产生的。文章作者在M81旋涡星系超软极亮X射线源(M81 ULS1)的光谱中,发现了蓝移的宽Hα发射线,其速度约为0.17倍的光速,这是相对论喷流的有力证据,也证认了M81 ULS1是一个微类星体。然而,它的相对论喷流不可能起源于白矮星,这与M81 ULS1的超软X射线光谱相矛盾。作者还发现超软极亮X射线源中的相对论喷流,可以被最新的处于超爱丁顿吸积的黑洞模型所解释。

Microquasars share the same phenomenon of the relativistic jets to their cousins of quasars, showing redshifted and blueshifted emission lines in their spectra, if the jets are dominated by baryonic matter. Such relativistic jets are not expected from sources with supersoft X-ray spectra, based on previous observations and classical theory. We report the discovery of blueshifted broad Hαemission lines, with the projected velocities ~17 percent of the speed of light, in optical spectra of an ultraluminous supersoft X-ray source（ULS） in the nearby galaxy M81（M81 ULS-1）,which is the strong evidence of jets with relativistic speeds. The relativistic jets are not expected to be launched from white dwarfs, which is hard to reconcile with its constant soft X-rays, but the relativistic jets in a ULS may possibly be explained by a long speculated super- critically accreting black hole.