arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0803.3516astro-phgr-qc
收藏

IC10 ~ X-1/NGC300 ~ X-1:BH-BH二进制的直接祖先

IC10~X-1/NGC300~X-1: the very immediate progenitors of BH-BH binaries

Tomasz Bulik, Krzysztof Belczynski, Andrea Prestwich

摘要:

我们研究了两个河外X射线双星:IC 10 X-1和NGC 300 X-1的未来演化。它们都由一个高质量BH($\sim 20-30 \msun$)和一个大质量WR伴星($\gtrsim 20 \msun$)吸积而成,并且都位于低金属丰度星系中。我们分析了系统的当前状态,并证明了这两个系统将非常迅速地($\lesssim 0.3$ Myr)形成紧密的BH-BH二进制短的合并时间($\sim 3$ Gyr)和大啁啾质量($\sim 15 \msun$)。BH-BH系统的形成似乎是不可避免的,因为{ \em(i)} WR伴星正好在它们的洛希瓣内,并且它们不膨胀,所以预计没有洛希瓣溢出,{ \em(ii)}即使强烈的WR风质量损失也不会去除足够的质量来阻止第二个BH的形成,{ \em(ii)}即使BH接收到大的出生反冲,这些系统紧密相连,几乎不可能被破坏。由于在2 Mpc内存在两个这样的直接BH-BH祖先系统,并且由于当前的引力波仪器LIGO/VIRGO(初始阶段)可以检测到$\sim 200$ Mpc的这种大规模BH-BH合并,因此经验估计的这种吸气的检测率为$R=3.36^{+8.29}_{-2.92}$,置信水平为99%。如果在目前的LIGO/VIRGO数据中没有检测到($s6$运行的未发布年份),那么这两个巨大的BH系统的存在构成了一个有趣的挑战。要么是引力辐射搜索对大质量的吸气不敏感,要么是对恒星演化物理学有一些根本的误解,直接导致了BH-BH双星的形成。

英文摘要:

We investigate the future evolution of two extragalactic X-ray binaries: IC10 X-1 and NGC300 X-1. Each of them consists of a high mass BH ($\sim 20-30 \msun$) accreting from a massive WR star companion ($\gtrsim 20 \msun$), and both are located in low metallicity galaxies. We analyze the current state of the systems and demonstrate that both systems will very quickly ($\lesssim 0.3$ Myr) form close BH-BH binaries with the short coalescence time ($\sim 3$ Gyr) and large chirp mass ($\sim 15 \msun$). The formation of BH-BH system seems unavoidable, as {\em (i)} WR companions are well within their Roche lobes and they do not expand so no Roche lobe overflow is expected, {\em (ii)} even intense WR wind mass loss does not remove sufficient mass to prohibit the formation of the second BH, {\em (ii)} even if BH receives the large natal kick, the systems are very closely bound and are almost impossible to disrupt. As there are two such immediate BH-BH progenitor systems within 2 Mpc and as the current gravitational wave instruments LIGO/VIRGO (initial stage) can detect such massive BH-BH mergers out to $\sim 200$ Mpc, the empirically estimated detection rate of such inspirals is $R=3.36^{+8.29}_{-2.92}$ at the 99% confidence level. If there is no detection in the current LIGO/VIRGO data (unreleased year of $s6$ run), the existence of these two massive BH systems poses an interesting challenge. Either the gravitational radiation search is not sensitive to massive inspirals or there is some fundamental misunderstanding of stellar evolution physics leading directly to the formation of BH-BH binaries.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑