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首页> 外文期刊>The Astrophysical journal >THE LOW-MASS X-RAY BINARY AND GLOBULAR CLUSTER CONNECTION IN VIRGO CLUSTER EARLY-TYPE GALAXIES: OPTICAL PROPERTIES
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THE LOW-MASS X-RAY BINARY AND GLOBULAR CLUSTER CONNECTION IN VIRGO CLUSTER EARLY-TYPE GALAXIES: OPTICAL PROPERTIES

机译：处女座早期星系中的低质量X射线二元和球状团簇连接：光学性质

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LMXBs form efficiently in GCs. By combining Chandra and HST ACS observations of 11 massive early-type galaxies in the Virgo Cluster, we use the most accurate identification of LMXBs and GCs to date to explore the optical properties of 270 GCs with LMXBs and 6488 GCs without detectable X-ray emission. More massive, redder, and more compact GCs are more likely to contain LMXBs. Unlike Galactic GCs, a large number of GCs with LMXBs have half-mass relaxation times >2.5 Gyr; GCs need not survive for more than five relaxation timescales to produce LMXBs. By fitting the dependence of the expected number of LMXBs per GC, λ_t, on the GC mass M, color (g — z), and half-mass radius r_(h, cor), we find that λ_t ∝ M~(1.24±0.08)x 10~(0.9_(-0.1)~(+0.2))~((g-z))r_(h,cor)~(-2.2±0.2). This rules out that the number of LMXBs per GC is linearly proportional to GC mass (99.89% confidence limit) and leads us to predict that most GCs with high X-ray luminosities contain a single LMXB. The detailed dependence of λ_t on GC properties appears mainly due to a dependence on the encounter rate Γ_h and the metallicity Z, λ_t ∝ Γ_h~(0.82±0.05)Z~(0.39±0.07). Our analysis provides strong evidence that dynamical formation and metallicity play the primary roles in determining the presence of an LMXB in extragalactic GCs. The shallower than linear encounter rate dependence requires an explanation by theories of dynamical binary formation. A metallicity-dependent variation in the number of neutron stars and black holes per unit GC mass, effects from irradiation-induced winds, or suppression of magnetic braking in metal-poor stars may all be consistent with our abundance dependence; all three scenarios require further development.
机译：LMXB在GC中有效形成。通过结合处女座星团中11个早期大型星系的Chandra和HST ACS观测，我们使用迄今为止最准确的LMXB和GC识别来探索270个带有LMXB和6488 GC且没有可检测到X射线发射的GC的光学特性。 。更大，更红，更紧凑的GC更有可能包含LMXB。与银河GC不同，大量带有LMXB的GC的半质量弛豫时间> 2.5 Gyr。 GC生产LMXB的时间不必超过五个弛豫时间范围。通过拟合每个GC的预期LMXB数λ_t对GC质量M，颜色（g — z）和半质量半径r_（h，cor）的依赖性，我们发现λ_t∝ M〜（1.24± 0.08）x 10〜（0.9 _（-0.1）〜（+0.2））〜（（gz））r_（h，cor）〜（-2.2±0.2）。这排除了每个GC中LMXB的数量与GC质量成线性比例（置信限为99.89％），并使我们预测大多数具有高X射线发光度的GC都包含一个LMXB。 λ_t对GC性质的详细依赖性主要是由于对相遇率Γ_h和金属性Z的依赖性所致，λ_t∝Γ_h〜（0.82±0.05）Z〜（0.39±0.07）。我们的分析提供了有力的证据，表明动力学形成和金属性在决定河外GC中LMXB的存在中起主要作用。比线性相遇率依赖关系浅的问题需要通过动态二进制形成理论进行解释。每单位GC质量中子星和黑洞的数量与金属性有关的变化，辐射诱导的风的影响或对金属贫乏的恒星中电磁制动的抑制都可能与我们对丰度的依赖相一致；这三种情况都需要进一步开发。

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