论文标题
原位极高的比率通过亚比索的形成和薄，重力不稳定的AGN碟片的恒星的迁移
In-situ extreme mass ratio inspirals via sub-parsec formation and migration of stars in thin, gravitationally unstable AGN discs
论文作者
论文摘要
我们研究了通过重力不稳定性在活性银河核（AGN）中超级质量黑洞（SMBH）周围通过重力不稳定性出生的恒星的性质，以及这如何随SMBH质量，增生速率或粘度而变化。我们用几何薄，稳态的圆盘溶液显示，当人们考虑初始条件（例如，重力不稳定区域的密度和温度）时，碎裂会导致不同的恒星种群。我们发现，在$ 10^6 \ rm m _ {\ odot} $ smbhs的圆盘上的不透明度可能会触发radii $ \ lyssim 10^{ - 2} $ pc的碎片，尽管条件会导致最初低恒星块的形成，该质量最初低于$ 0.1-0.5.5.5.5.5 \ rm m m _ {圆盘围绕更大的SMBH（$ M _ {\ rm BH} = 10^{7-8} \ rm M _ {\ odot} $）形式适中或超级质量的星星（大多数$ 10^{0-2} {0-2} \ rm m _ {rm m _ {\ odot} $）。使用线性迁移估计值，我们讨论了三个结果：恒星迁移直到被潮汐破坏，被作为极端质量比的灵感（EMRIS）或圆盘散布后剩余的。对于单个AGN活性周期，我们发现EMRI速率$ r _ {\ rm emri} \ sim 0-10^{ - 4} \ rm yr yr^{ - 1} $ a agn假设SF效率$ε= 1-30 \％$ $。如果发生EMRIS，这意味着在本地宇宙中的体积速率高达$ 0.5-10 \ rm yr^{ - 1} gpc^{ - 3} $。费率对$ M _ {\ rm bh} = 10^6 \ rm m _ {\ odot} $的模型参数特别敏感，仅当恒星才能吸收到$ 10 $太阳能块时，才会发生Emris。我们的结果提供了进一步的证据，表明气体包含的EMRI可以贡献大量的事件，可通过Millihz引力波检测器（例如Lisa）检测到。我们的圆盘解决方案表明存在迁移陷阱，这已经发现了更大的SMBH椎间盘。最后，椎间盘寿命后的恒星存活人群对银河系核中的恒星圆盘产生了影响。
We investigate the properties of stars born via gravitational instability in accretion discs around supermassive black holes (SMBHs) in active galactic nuclei (AGN), and how this varies with the SMBH mass, accretion rate, or viscosity. We show with geometrically thin, steady-state disc solutions that fragmentation results in different populations of stars when one considers the initial conditions (e.g. density and temperature of the gravitationally unstable regions). We find that opacity gaps in discs around $10^6 \rm M_{\odot}$ SMBHs can trigger fragmentation at radii $\lesssim 10^{-2}$ pc, although the conditions lead to the formation of initially low stellar masses around $0.1-0.5 \rm M_{\odot}$. Discs around more massive SMBHs ($M_{\rm BH} =10^{7-8} \rm M_{\odot}$) form moderately massive or supermassive stars (the majority at $10^{0-2} \rm M_{\odot}$). Using linear migration estimates, we discuss three outcomes: stars migrate till they are tidally destroyed, accreted as extreme mass ratio inspirals (EMRIs), or leftover after disc dispersal. For a single AGN activity cycle, we find a lower-limit for the EMRI rate $R_{\rm emri}\sim 0-10^{-4} \rm yr^{-1}$ per AGN assuming a SF efficiency $ε=1-30\%$. In cases where EMRIs occur, this implies a volumetric rate up to $0.5-10 \rm yr^{-1} Gpc^{-3}$ in the local Universe. The rates are particularly sensitive to model parameters for $M_{\rm BH}=10^6 \rm M_{\odot}$, for which EMRIs only occur if stars can accrete to $10$s of solar masses. Our results provide further evidence that gas-embedded EMRIs can contribute a substantial fraction of events detectable by milliHz gravitational wave detectors such as LISA. Our disc solutions suggest the presence of migration traps, as has been found for more massive SMBH discs. Finally, the surviving population of stars after the disc lifetime leaves implications for stellar discs in galactic nuclei.
