Primordial black holes capture by stars and induced collapse to low-mass stellar black holes
Primordial black holes capture by stars and induced collapse to low-mass stellar black holes
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原始黑洞被恒星捕获并导致塌缩成低质量恒星黑洞
DOI：
10.1093/mnras/stac2647
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发表时间：
2022
期刊：
影响因子：
64.8
通讯作者：
P. Gil
中科院分区：
文献类型：
--
作者：
M. Oncins;Jordi Miralda;Jordi L. Guti'errez;P. Gil
小行星质量窗口中的原始黑洞可能构成所有的暗物质，当它们以足够低的速度穿过恒星时，它们可以被恒星捕获。在星星形成过程中被放置在一个束缚轨道上之后，如果轨道碰巧是高度偏心的，它们可以反复穿过星星，通过动力摩擦减速，并最终进入恒星核心。这些捕获率是最高的高暗物质密度和低速度色散的晕，当第一颗恒星在红移？20块我们计算这个捕获率为0的低金属丰度恒星。3到1 M（cid：12），并发现在第一个矮星系中形成的这些恒星中有很大一部分会捕获一个原始黑洞，然后通过吸积增长到一个质量可能接近总星星质量的质量。我们表明，原始黑洞的捕获率不依赖于他们的质量在这个小行星的质量窗口，不应该受到太多的外部潮汐扰动。这些低质量恒星黑洞今天可以在银河系中的低金属量，旧的双星系统中发现，其中包含幸存的低质量主序星星星或白色矮星，或者通过与另一个紧凑物体合并时发出的引力波。在标准的恒星演化理论中，没有任何机制可以形成低于克拉塞卡质量的黑洞，因此探测低质量黑洞将从根本上影响我们对恒星演化、暗物质和早期宇宙的理解。
Primordial black holes in the asteroid-mass window, which might constitute all the dark matter, can be captured by stars when they traverse them at low enough velocity. After being placed on a bound orbit during star formation, they can repeatedly cross the star if the orbit happens to be highly eccentric, slow down by dynamical friction and end up in the stellar core. The rate of these captures is highest in halos of high dark matter density and low velocity dispersion, when the first stars form at redshift ? ∼ 20. We compute this capture rate for low-metallicity stars of 0 . 3 to 1 M (cid:12) , and find that a high fraction of these stars formed in the first dwarf galaxies would capture a primordial black hole, which would then grow by accretion up to a mass that may be close to the total star mass. We show the capture rate of primordial black holes does not depend on their mass over this asteroid-mass window, and should not be much affected by external tidal perturbations. These low-mass stellar black holes could be discovered today in low-metallicity, old binary systems in the Milky Way containing a surviving low-mass main-sequence star or a white dwarf, or via gravitational waves emitted in a merger with another compact object. No mechanisms in standard stellar evolution theory are known to form black holes below the Chandrasekhar mass, so detecting a low-mass black hole would fundamentally impact our understanding of stellar evolution, dark matter and the early Universe.