论文标题
sgr a*的通量分布
The Flux Distribution of Sgr A*
论文作者
论文摘要
银河中心黑洞Sagittarius A*是一个可变的NIR源，表现出明亮的通量偏移，称为耀斑。通量分布的低流量密度周转率低于当前单孔望远镜的灵敏度。我们使用VLTI的重力仪器的前所未有的分辨率。我们的光曲线未引起人们的注意，克服了先前的光度研究的混淆极限。我们使用标准统计方法分析光曲线并获得通量分布。我们发现SGRA*的通量分布以（1.1 \ pm0.3）mjy的中间通量密度转移。我们测量通量分布的百分位数，并使用它们来限制NIR K波段SED。此外，我们发现磁通分布本质上是直接右转到对数空间中较高通量密度的。几乎没有观察到低于0.1MJY的通量密度。因此，单个PowerLaw或对数正态分布不足以描述其完整的观测通量分布。但是，如果人们考虑到高通量密度下的幂律部分，则对数正态分布可以描述观察到的通量分布的下端。我们确认了SGR〜A*的RMS-FLUX关系，并发现我们观察中所有通量密度是线性的。我们得出的结论是，sgr〜a*具有两种状态：大部分发射是在具有明确定义的中位通量密度的对数正态过程中产生的，并且这种静止的发射是由零星的耀斑补充的，从而产生了观察到的磁通量分布的电源范围。
The Galactic Center black hole Sagittarius A* is a variable NIR source that exhibits bright flux excursions called flares. The low-flux density turnover of the flux distribution is below the sensitivity of current single-aperture telescopes. We use the unprecedented resolution of the GRAVITY instrument at the VLTI. Our light curves are unconfused, overcoming the confusion limit of previous photometric studies. We analyze the light curves using standard statistical methods and obtain the flux distribution. We find that the flux distribution of SgrA* turns over at a median flux density of (1.1\pm0.3)mJy. We measure the percentiles of the flux distribution and use them to constrain the NIR K-band SED. Furthermore, we find that the flux distribution is intrinsically right-skewed to higher flux density in log space. Flux densities below 0.1mJy are hardly ever observed. In consequence, a single powerlaw or lognormal distribution does not suffice to describe the observed flux distribution in its entirety. However, if one takes into account a power law component at high flux densities, a lognormal distribution can describe the lower end of the observed flux distribution. We confirm the RMS-flux relation for Sgr~A* and find it to be linear for all flux densities in our observation. We conclude that Sgr~A* has two states: the bulk of the emission is generated in a lognormal process with a well-defined median flux density and this quiescent emission is supplemented by sporadic flares that create the observed power law extension of the flux distribution.
