OPTICAL THERMONUCLEAR TRANSIENTS FROM TIDAL COMPRESSION OF WHITE DWARFS AS TRACERS OF THE LOW END OF THE MASSIVE BLACK HOLE MASS FUNCTION
OPTICAL THERMONUCLEAR TRANSIENTS FROM TIDAL COMPRESSION OF WHITE DWARFS AS TRACERS OF THE LOW END OF THE MASSIVE BLACK HOLE MASS FUNCTION
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DOI：
10.3847/0004-637x/819/1/3
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
M. MacLeod;J. Guillochon;E. Ramirez-Ruiz;D. Kasen;S. Rosswog
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文献类型：
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作者：
M. MacLeod;J. Guillochon;E. Ramirez-Ruiz;D. Kasen;S. Rosswog
在本文中，我们用中等质量（≈103-105 M⊙）的大质量黑洞（MBHs）模拟了白矮星（WD）恒星潮汐扰动的可观测特征。当WD通过MBH的潮汐场足够深时，这些特征包括在最大压缩期间燃烧产生的热核瞬变。我们结合了一个流体动力学模拟，其中包括0.6 M⊙C/O WD中断的核燃烧与蒙特卡罗辐射传输计算，以综合具有代表性的瞬态特性。瞬态辐射出现在光学波段，其光曲线和光谱让人想起I型超新星。这些特性与观测角度密切相关，关键的光谱特征是≈10,000 km s−1多普勒频移，这是由于未绑定的抛射物的轨道运动造成的。He WDs的破坏可能会产生大量的中等质量元素，为富钙瞬态的产生提供了可能的机制。伴随而来的多波长瞬变是由吸积推动的，并产生于新生的吸积盘和相对论性喷流。如果中等质量黑洞存在，其数量密度与超大质量黑洞相似，那么无论是高能宽视场监测器还是即将到来的光学调查，每年都应该能探测到数十到数百次的WD潮汐中断。因此，目前探测它们的最佳策略可能是对持续时间异常长的高能瞬态进行深度光学跟踪。因此，当前和即将进行的调查对这些瞬态的检测率或未检测率可以用来对MBH质量函数向中等质量的外推施加有意义的约束。
In this paper, we model the observable signatures of tidal disruptions of white dwarf (WD) stars using massive black holes (MBHs) of moderate mass, ≈103–105 M⊙. When the WD passes deep enough within the MBH’s tidal field, these signatures include thermonuclear transients from burning during maximum compression. We combine a hydrodynamic simulation that includes nuclear burning of the disruption of a 0.6 M⊙ C/O WD with a Monte Carlo radiative transfer calculation to synthesize the properties of a representative transient. The transient’s emission emerges in the optical, with light curves and spectra reminiscent of Type I supernovae. The properties are strongly viewing angle dependent, and key spectral signatures are ≈10,000 km s−1 doppler shifts, due to the orbital motion of the unbound ejecta. Disruptions of He WDs likely produce large quantities of intermediate-mass elements, offering a possible production mechanism for Ca-rich transients. Accompanying multi-wavelength transients are fueled by accretion and arise from the nascent accretion disk and relativistic jet. If MBHs of moderate mass exist with number densities similar to those of supermassive BHs, both high-energy wide-field monitors and upcoming optical surveys should detect tens to hundreds of WD tidal disruptions per year. The current best strategy for their detection may therefore be deep optical follow-up of high-energy transients of unusually long duration. The detection rate or the nondetection of these transients by current and upcoming surveys can thus be used to place meaningful constraints on the extrapolation of the MBH mass function to moderate masses.