MERGERS OF UNEQUAL-MASS GALAXIES: SUPERMASSIVE BLACK HOLE BINARY EVOLUTION AND STRUCTURE OF MERGER REMNANTS
文献类型：期刊论文
| 作者 | Khan, Fazeel Mahmood1,2; Preto, Miguel1; Berczik, Peter1,3,4 ; Berentzen, Ingo1,5; Just, Andreas1; Spurzem, Rainer1,3,6
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| 刊名 | ASTROPHYSICAL JOURNAL
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| 出版日期 | 2012-04-01 |
| 卷号 | 749期号:2 |
| 关键词 | black hole physics galaxies: evolution galaxies: interactions galaxies: nuclei gravitational waves |
| 英文摘要 | Galaxy centers are residing places for supermassive black holes (SMBHs). Galaxy mergers bring SMBHs close together to form gravitationally bound binary systems, which, if able to coalesce in less than a Hubble time, would be one of the most promising sources of gravitational waves (GWs) for the Laser Interferometer Space Antenna. In spherical galaxy models, SMBH binaries stall at a separation of approximately 1 pc, leading to the "final parsec problem" (FPP). On the other hand, it has been shown that merger-induced triaxiality of the remnant in equal-mass mergers is capable of supporting a constant supply of stars on the so-called centrophilic orbits that interact with the binary and thus avoid the FPP. In this paper, using a set of direct N-body simulations of mergers of initially spherically symmetric galaxies with different mass ratios, we show that the merger-induced triaxiality is also able to drive unequal-mass SMBH binaries to coalescence. The binary hardening rates are high and depend only weakly on the mass ratios of SMBHs for a wide range of mass ratios q. There is, however, an abrupt transition in the hardening rates for mergers with mass ratios somewhere between q similar to 0.05 and 0.1, resulting from the monotonic decrease of merger-induced triaxiality with mass ratio q, as the secondary galaxy becomes too small and light to significantly perturb the primary, i.e., the more massive one. The hardening rates are significantly higher for galaxies having steep cusps in comparison with those having shallow cups at centers. The evolution of the binary SMBH leads to relatively shallower inner slopes at the centers of the merger remnants. The stellar mass displaced by the SMBH binary on its way to coalescence is similar to 1-5 times the combined mass of binary SMBHs. The coalescence timescales for SMBH binary with mass similar to 10(6) M-circle dot are less than 1 Gyr and for those at the upper end of SMBH masses 10(9) M-circle dot are 1-2 Gyr for less eccentric binaries whereas they are less than 1 Gyr for highly eccentric binaries. SMBH binaries are thus expected to be promising sources of GWs at low and high redshifts. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000302785700051 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/6105]  |
| 专题 | 国家天文台_星系宇宙学研究部 |
| 作者单位 | 1.Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, D-69120 Heidelberg, Germany 2.Govt Coll Univ, Dept Phys, Lahore 54000, Pakistan 3.Chinese Acad Sci, Natl Astron Observ China, Beijing 100012, Peoples R China 4.Natl Acad Sci Ukraine, Main Astron Observ, UA-03680 Kiev, Ukraine 5.Heidelberg Inst Theoret Studies, D-69118 Heidelberg, Germany 6.Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China |
| 推荐引用方式 GB/T 7714 | Khan, Fazeel Mahmood,Preto, Miguel,Berczik, Peter,et al. MERGERS OF UNEQUAL-MASS GALAXIES: SUPERMASSIVE BLACK HOLE BINARY EVOLUTION AND STRUCTURE OF MERGER REMNANTS[J]. ASTROPHYSICAL JOURNAL,2012,749(2). |
| APA | Khan, Fazeel Mahmood,Preto, Miguel,Berczik, Peter,Berentzen, Ingo,Just, Andreas,&Spurzem, Rainer.(2012).MERGERS OF UNEQUAL-MASS GALAXIES: SUPERMASSIVE BLACK HOLE BINARY EVOLUTION AND STRUCTURE OF MERGER REMNANTS.ASTROPHYSICAL JOURNAL,749(2). |
| MLA | Khan, Fazeel Mahmood,et al."MERGERS OF UNEQUAL-MASS GALAXIES: SUPERMASSIVE BLACK HOLE BINARY EVOLUTION AND STRUCTURE OF MERGER REMNANTS".ASTROPHYSICAL JOURNAL 749.2(2012). |
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