Hanging on the cliff: EMRI formation with local two-body relaxation and post-Newtonian dynamics

Davide Mancieri, Luca Broggi, Matteo Bonetti, Alberto Sesana
{"title":"Hanging on the cliff: EMRI formation with local two-body relaxation and post-Newtonian dynamics","authors":"Davide Mancieri, Luca Broggi, Matteo Bonetti, Alberto Sesana","doi":"arxiv-2409.09122","DOIUrl":null,"url":null,"abstract":"Extreme mass ratio inspirals (EMRIs) are anticipated to be primary\ngravitational wave sources for LISA (Laser Interferometer Space Antenna). They\nform in dense nuclear clusters when a compact object (CO) is captured by the\ncentral massive black holes (MBHs) due to frequent two-body interactions among\norbiting objects. We present a novel Monte Carlo approach to evolve the\npost-Newtonian (PN) equations of motion of a CO orbiting an MBH accounting for\ntwo-body relaxation locally on the fly, without the assumption of\norbit-averaging. We estimate the fraction $S(a_0)$ of EMRIs to total captures\n(including direct plunges, DPs) as a function of the initial semi-major axis\n$a_0$ for COs around MBHs of $M_\\bullet\\in[10^4\\,{\\rm\nM}_\\odot,4\\times10^6\\,{\\rm M}_\\odot]$. Previous results indicate\n$S(a_0)\\rightarrow 0$ at large $a_0$, with a sharp transition from EMRIs to DPs\naround a critical scale $a_{\\rm c}$. This notion has been recently challenged\nfor low-mass MBHs, with EMRIs forming at $a\\gg a_{\\rm c}$, the so-called\n\"cliffhangers''. Our simulations confirm their existence, at larger numbers\nthan previously expected. Cliffhangers start to appear for\n$M_\\bullet\\lesssim3\\times 10^5\\,{\\rm M}_\\odot$ and can account for up to 55% of\nthe overall EMRIs formed. We find $S(a_0)\\gg 0$ for $a\\gg a_{\\rm c}$, reaching\nvalues as high as 0.6 for $M_\\bullet=10^4\\,{\\rm M}_\\odot$, much larger than\npreviously found. We find that the PN description of the system greatly\nenhances the number of EMRIs by shifting $a_{\\rm c}$ to larger values at all\nMBH masses, and that the local treatment of relaxation significantly boosts the\nnumber of cliffhangers for small MBHs. Our work shows the limitations of\nstandard assumptions for estimating EMRI formation rates, most importantly\ntheir dynamical models. Future estimates of rates and properties of EMRIs\ndetectable by LISA should account for these improvements.","PeriodicalId":501041,"journal":{"name":"arXiv - PHYS - General Relativity and Quantum Cosmology","volume":"5 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - General Relativity and Quantum Cosmology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.09122","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0

Abstract

Extreme mass ratio inspirals (EMRIs) are anticipated to be primary gravitational wave sources for LISA (Laser Interferometer Space Antenna). They form in dense nuclear clusters when a compact object (CO) is captured by the central massive black holes (MBHs) due to frequent two-body interactions among orbiting objects. We present a novel Monte Carlo approach to evolve the post-Newtonian (PN) equations of motion of a CO orbiting an MBH accounting for two-body relaxation locally on the fly, without the assumption of orbit-averaging. We estimate the fraction $S(a_0)$ of EMRIs to total captures (including direct plunges, DPs) as a function of the initial semi-major axis $a_0$ for COs around MBHs of $M_\bullet\in[10^4\,{\rm M}_\odot,4\times10^6\,{\rm M}_\odot]$. Previous results indicate $S(a_0)\rightarrow 0$ at large $a_0$, with a sharp transition from EMRIs to DPs around a critical scale $a_{\rm c}$. This notion has been recently challenged for low-mass MBHs, with EMRIs forming at $a\gg a_{\rm c}$, the so-called "cliffhangers''. Our simulations confirm their existence, at larger numbers than previously expected. Cliffhangers start to appear for $M_\bullet\lesssim3\times 10^5\,{\rm M}_\odot$ and can account for up to 55% of the overall EMRIs formed. We find $S(a_0)\gg 0$ for $a\gg a_{\rm c}$, reaching values as high as 0.6 for $M_\bullet=10^4\,{\rm M}_\odot$, much larger than previously found. We find that the PN description of the system greatly enhances the number of EMRIs by shifting $a_{\rm c}$ to larger values at all MBH masses, and that the local treatment of relaxation significantly boosts the number of cliffhangers for small MBHs. Our work shows the limitations of standard assumptions for estimating EMRI formation rates, most importantly their dynamical models. Future estimates of rates and properties of EMRIs detectable by LISA should account for these improvements.
查看原文
分享 分享
微信好友 朋友圈 QQ好友 复制链接
本刊更多论文
悬崖勒马:利用局部二体弛豫和后牛顿动力学形成 EMRI
极端质量比吸气(EMRIs)预计将成为激光干涉仪空间天线(LISA)的主要引力波源。由于轨道天体之间频繁的双体相互作用,当一个紧凑天体(CO)被中心大质量黑洞(MBHs)捕获时,它们就会在致密核星团中形成。我们提出了一种新颖的蒙特卡洛方法来演化绕 MBH 运行的 CO 的后牛顿(PN)运动方程,无需假定轨道平均。对于围绕M_\bullet\in[10^4\,{\rmM}_\odot,4\times10^6\,{\rm M}_\odot]$的MBH的一氧化碳,我们估算了作为初始半长轴$a_0$函数的EMRIs占总捕获量(包括直接坠落,DPs)的分数$S(a_0)$。以前的结果表明,在大尺度 $a_0$ 时,$S(a_0)rightarrow 0$,在临界尺度 $a_{\rm c}$ 附近,会从 EMRIs 急剧过渡到 DPs。这一概念最近在低质量MBHs上受到了挑战,EMRIs在$a\gg a_{\rm c}$时形成,即所谓的 "悬崖"。我们的模拟证实了它们的存在,而且数量比之前预期的要多。悬崖开始出现于$M_\bullet\lesssim3\times 10^5\,{\rm M}_\odot$,并且可以占到整个EMRI形成的55%。我们发现$S(a_0)gg 0$为$a\gg a_{\rm c}$,当$M_\bullet=10^4\,{\rm M}_\odot$时,数值高达0.6,远远大于之前发现的数值。我们发现,系统的PN描述通过在所有MBH质量下将$a_{\rm c}$移动到更大的值,极大地增加了EMRI的数量,而且对弛豫的局部处理极大地增加了小MBH的悬案数量。我们的工作显示了用于估计EMRI形成率的标准假设的局限性,其中最重要的是它们的动力学模型。未来对 LISA 可探测到的 EMRI 的速率和性质的估计应考虑到这些改进。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 去求助
来源期刊
自引率
0.00%
发文量
0
期刊最新文献
Matter Geometry Coupling and Casimir Wormhole Geometry Multi-field TDiff theories for cosmology Field Sources for $f(R,R_{μν})$ Black-Bounce Solutions: The Case of K-Gravity Magnetic Reconnection and Energy Extraction from a Konoplya-Zhidenko rotating non-Kerr black hole Holographic Einstein Rings of AdS Black Holes in Horndeski Theory
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
已复制链接
已复制链接
快去分享给好友吧!
我知道了
×
扫码分享
扫码分享
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1