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arXiv 2203.06187astro-ph.GAastro-ph.SR
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AGN星系中不朽恒星星族的效应

Effects of an Immortal Stellar Population in AGN Disks

Adam S. Jermyn, Alexander J. Dittmann, B. McKernan, K. E. S. Ford, Matteo Cantiello

摘要:

恒星很可能嵌在活动星系核(AGN)的气体盘中。理论模型预测,在圆盘的内部区域,这些恒星迅速吸积,新鲜气体补充氢的速度比燃烧成氦的速度更快,有效地阻止了它们在氢燃烧时的演化。我们产生的数量级的估计,这样的恒星在一个基准AGN磁盘。我们发现数的顺序$10^{2-4}$,局限于内部$r_{\rm cap} \sim 3000 r_s \sim 0.03\rm pc$。这些恒星可以深刻地改变活动星系核盘的化学性质,使其富含氦并耗尽氢,两者的数量都是有序统一的。我们进一步考虑合并这些恒星和其他磁盘对象之间,这表明恒星恒星合并导致快速的质量损失从残留物恢复平衡质量,而恒星紧凑的对象合并可能会导致异国情调的结果,甚至主机内的二元黑洞合并。最后,我们研究这些恒星的反应,磁盘消散接近其寿命的结束,并发现他们可能会返回质量磁盘足够快,以延长其寿命的几个因素和/或可能会驱动强大的外流磁盘。在活动星系核之后,这些恒星迅速失去质量,并在$10M_{\odot}$周围形成一群恒星质量的黑洞。由于嵌入的恒星和盘之间的复杂和不确定的相互作用,他们的似是而非的无处不在,和他们的秩序统一的影响盘的结构和演化,他们必须包括在现实的磁盘模型。

英文摘要:

Stars are likely embedded in the gas disks of Active Galactic Nuclei (AGN). Theoretical models predict that in the inner regions of the disk these stars accrete rapidly, with fresh gas replenishing hydrogen in their cores faster than it is burned into helium, effectively stalling their evolution at hydrogen burning. We produce order-of-magnitude estimates of the number of such stars in a fiducial AGN disk. We find numbers of order $10^{2-4}$, confined to the inner $r_{\rm cap} \sim 3000 r_s \sim 0.03\rm pc$. These stars can profoundly alter the chemistry of AGN disks, enriching them in helium and depleting them in hydrogen, both by order-unity amounts. We further consider mergers between these stars and other disk objects, suggesting that star-star mergers result in rapid mass loss from the remnant to restore an equilibrium mass, while star-compact object mergers may result in exotic outcomes and even host binary black hole mergers within themselves. Finally, we examine how these stars react as the disk dissipates towards the end of its life, and find that they may return mass to the disk fast enough to extend its lifetime by a factor of several and/or may drive powerful outflows from the disk. Post-AGN, these stars rapidly lose mass and form a population of stellar mass black holes around $10M_{\odot}$. Due to the complex and uncertain interactions between embedded stars and the disk, their plausible ubiquity, and their order unity impact on disk structure and evolution, they must be included in realistic disk models.

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。

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