Microlensing by Stellar Black Holes around Sagittarius A*
Microlensing by Stellar Black Holes around Sagittarius A*
复制标题
人马座 A* 周围恒星黑洞的微透镜效应
DOI：
10.1086/323986
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
J. Miralda
中科院分区：
文献类型：
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作者：
J. Chanamé;A. Gould;J. Miralda
我们表明，在任何给定的时间，银河系中心黑洞Sgr A* 预计是微透镜Nlens ~ 1.7凸星，如果较暗的图像的可探测性阈值是Kthr = 21，和Nlens ~ 8源，如果Kthr = 23。然后，透镜图像提供了一种独特的方法来检测预测聚集在Sgr A* 周围的恒星质量黑洞。如果黑洞靠近微透镜图像经过，它将引起短暂（数周）的微透镜事件。我们表明，恒星质量黑洞的质量和投影速度都可以从这样的事件明确测量，只要观察到焦散交叉或天体测量位移。对于Kthr = 23和中等放大倍率的Sgr A*，微透镜事件率从一个集群的20000黑洞半径为0.7 pc的只有0.06年-1;然而，如果高度放大图像的星星被发现，由恒星黑洞的事件率将高得多。此外，由Sgr A* 透镜化的Nlens光源提供了一个独特的探测银河系中心后面沿着2Nlens视线的消光。
We show that at any given time, the Galactocentric black hole Sgr A* is expected to be microlensing Nlens ~ 1.7 bulge stars if the threshold of detectability of the fainter image is Kthr = 21, and Nlens ~ 8 sources if Kthr = 23. The lensed images then provide a unique way to detect stellar-mass black holes predicted to cluster around Sgr A*. If a black hole passes close to a microlensed image, it will give rise to a short (weeks long) microlensing event. We show that the mass and projected velocity of the stellar-mass black hole can both be measured unambiguously from such an event, provided that either a caustic crossing is observed or the astrometric displacement is measured. For Kthr = 23 and moderate magnifications by Sgr A*, the microlensing event rate from a cluster of 20000 black holes within a radius of 0.7 pc is only 0.06 yr- 1; however, if highly magnified images of a star were found, the rate of events by the stellar black holes would be much higher. In addition, the Nlens sources lensed by Sgr A* provide a unique probe of extinction behind the Galactic center along 2Nlens lines of sight.