通过XMM-Newton观察到的来自SgrA * 的X射线打嗝。半天内捕捉到的第二亮耀斑和三个中等耀斑
X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
摘要：
在2007年春天，我们用XMM观测到了SgrA*，总曝光量约为230 ks。我们对这次活动中探测到的新的X射线耀斑进行了定时和光谱分析。为了以一致的方式研究耀斑光谱特性的范围，我们还使用相同的分析程序和最新的校准重新处理了以前报告的快速耀斑的存档XMM数据。在光谱拟合过程中考虑了尘埃散射。我们还使用钱德拉存档的SgrA* 静止状态的观测结果进行比较。在2007年4月4日，我们在大约1/2天的时间间隔内首次观测到X射线耀斑的发生率增强，一个明亮的耀斑之后是三个幅度更适中的耀斑。前一个事件代表了有记录以来Sgr A* 第二亮的X射线耀斑。这个新的明亮耀斑与2002年10月3日观测到的非常明亮的耀斑具有相似的光变曲线形状（几乎对称），持续时间（~ 3 ks）和光谱特征。在考虑尘埃散射效应的吸收幂律模型下，新耀斑的光谱参数为：N_H=12.3（+2.1，-1.8）e ~（22）cm ~（-2），γ = 2.3+/-0.3。以下三个中等耀斑的光谱参数拟合的总和，虽然较低，但在误差条内与明亮的耀斑是兼容的。在耀斑期间发现的柱密度，对于幂律，至少比从（尘埃）目视消光到SgrA*（AV~25等）预期的值高两倍。然而，我们的拟合与钱德拉获得的SgrA* 静态光谱表明，过剩的柱密度已经存在于非燃烧阶段。到目前为止，从SgrA* 观测到的两个最明亮的X射线耀斑显示出相似的软光谱。
英文摘要：
[truncated] In Spring 2007, we observed SgrA* with XMM with a total exposure of ~230ks. We have performed timing and spectral analysis of the new X-ray flares detected during this campaign. To study the range of flare spectral properties, in a consistent manner, we have also reprocessed, using the same analysis procedure and the latest calibration, archived XMM data of previously reported rapid flares. The dust scattering was taken into account during the spectral fitting. We also used Chandra archived observations of the quiescent state of SgrA* for comparison. On April 4, 2007, we observed for the first time within a time interval of ~1/2 day, an enhanced incidence rate of X-ray flaring, with a bright flare followed by three flares of more moderate amplitude. The former event represents the second brightest X-ray flare from Sgr A* on record. This new bright flare exhibits similar light-curve shape (nearly symmetrical), duration (~3ks) and spectral characteristics to the very bright flare observed in October 3, 2002. The measured spectral parameters of the new bright flare, assuming an absorbed power law model taken into account dust scattering effect, are N_H=12.3(+2.1,-1.8)e22 cm-2 and Gamma~2.3+/-0.3 calculated at the 90% c.l. The spectral parameter fits of the sum of the three following moderate flares, while lower, are compatible within the error bars with those of the bright flares. The column density found, for a power-law, during the flares is at least two times higher than the value expected from the (dust) visual extinction toward SgrA* (AV~25 mag). However, our fitting of the SgrA* quiescent spectra obtained with Chandra shows that an excess of column density is already present during the non-flaring phase. The two brightest X-ray flares observed so far from SgrA* exhibited similar soft spectra.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
