DYNAMICAL AND EVOLUTIONARY CONSTRAINTS ON THE NATURE AND ORIGIN OF HYPERVELOCITY STARS
DYNAMICAL AND EVOLUTIONARY CONSTRAINTS ON THE NATURE AND ORIGIN OF HYPERVELOCITY STARS
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DOI：
10.1088/0004-637x/690/1/795
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发表时间：
2007-12
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影响因子：
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通讯作者：
H. Perets
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作者：
H. Perets
近年来，在银河系晕中观测到了几颗超高速星。这样的恒星被认为是通过银河系中心（GC）的大质量黑洞（MBH）附近的动力学相互作用而喷出的。三种情况下，他们的弹射建议：由MBH的二进制中断，由吸入的中等质量黑洞（IMBH）和散射恒星黑洞（SBH）靠近MBH。这些场景涉及GC中不同的恒星种群。在这里，我们使用的GC恒星人口的动态和进化的参数，以获得强有力的约束HVS的性质和起源的观测。我们表明，IMBH内旋的情况下，需要太多的）主序星B存在接近MBH（<0.01秒差距）的时间内旋，目前的观测显示这样的恒星。SBH的散射也需要在GC中观察到太多的B星，但可能只占目前观察到的HVS的一小部分。二进制中断的情况仍然与目前的观察一致。此外，它表明，最近建议的签名HVS起源，如超高速双星和缓慢旋转的HVS比建议的要弱得多，需要太大的统计。此外，我们表明，由于接近MBH的条件下，大多数二进制星星系统预计不会在这个地区生存很长时间。因此，独特的恒星人口，需要长期演变的双星预计不会被弹出的HVS在SBHS散射机制（这也可能与最近观察到的不对称的速度分布的HVS）。
In recent years, several hypervelocity stars (HVSs) have been observed in the halo of our Galaxy. Such stars are thought to be ejected through dynamical interactions near the massive black hole (MBH) in the Galactic center (GC). Three scenarios have been suggested for their ejection: binary disruption by an MBH, scattering by inspiraling intermediate mass black hole (IMBH) and scattering by stellar black holes (SBHs) close to MBH. These scenarios involve different stellar populations in the GC. Here we use observations of the GC stellar population together with dynamical and evolutionary arguments to obtain strong constraints on the nature and origin of HVSs. We show that the IMBH inspiral scenario requires too many ) main-sequence B stars to exist close to the MBH (<0.01 pc) at the time of inspiral, where current observations show such stars. Scattering by SBHs also require too many B stars to be observed in the GC, but may contribute a small fraction of the currently observed HVSs. The binary disruption scenario is still consistent with current observations. In addition, it is shown that recently suggested signatures for HVSs origin such as hypervelocity binaries and slow rotating HVSs are much weaker than suggested and require too large statistics. In addition, we show that due to the conditions close to the MBH most binary star systems are not expected to survive for long in this region. Consequently, unique stellar populations that require long evolution in binaries are not expected to be ejected as HVSs in the SBHs scattering mechanisms (this may also be related to the recently observed asymmetry in the velocity distribution of HVSs).