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arXiv 2210.02308astro-ph.GA
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通过多次吸积事件组装高红移类星体的黑洞质量与光度函数

The Assembly of Black Hole Mass and Luminosity Functions of High-redshift Quasars via Multiple Accretion Episodes

Wenxiu Li, Kohei Inayoshi, Masafusa Onoue, Daisuke Toyouchi

AI总结:

本研究基于半解析模型构建了经历多次吸积爆发的高红移类星体的QLF与BHMF,发现适度超爱丁顿吸积能重现$z\simeq 6$的观测,并预测了其红移演化与密度衰减。

摘要:

类星体光度函数(QLF)和黑洞质量函数(BHMF)的早期演化编码了决定高红移($z$)类星体中超大质量黑洞(BHs)辐射与吸积过程物理学的关键信息。尽管QLF的形状已由近期观测所约束,但开发一个自洽解释其与BH增长相关的红移演化的理论模型仍具挑战。本研究基于BH形成与增长的半解析模型,构建了经历多次吸积爆发的早期BH群体的QLF和BHMF,每次爆发中按照Schechter分布函数赋予一个恒定的爱丁顿比率。我们最佳拟合模型以重现$z\simeq 6$处观测到的QLF和BHMF表明,发生了数次适度超爱丁顿吸积事件,每次持续$τ\simeq 20-30$ Myr。。对于到$z\simeq 6$时达到$\gtrsim 10^8~M_\odot$的大质量BH,其在超爱丁顿相位的平均占空比约为$15\\%$几乎是整个群体的两倍。我们还发现,由于类星体巡天的探测极限,观测到的爱丁顿比率分布函数偏向对数正态形状。预测的QLF和BHMF的红移演化表明,在$z\gtrsim 6$时宇宙体积内的数密度和质量密度快速衰减。这些结果将由James Webb Space Telescope、Roman Space Telescope和Euclid的未来深空与广域巡天揭示。

英文摘要:

The early evolution of the quasar luminosity function (QLF) and black hole mass function (BHMF) encodes key information on the physics determining the radiative and accretion processes of supermassive black holes (BHs) in high-$z$ quasars. Although the QLF shape has been constrained by recent observations, it remains challenging to develop a theoretical model that explains its redshift evolution associated with BH growth self-consistently. In this study, based on a semi-analytical model for the BH formation and growth, we construct the QLF and BHMF of the early BH population that experiences multiple accretion bursts, in each of which a constant Eddington ratio is assigned following a Schechter distribution function. Our best-fit model to reproduce the observed QLF and BHMF at $z\simeq 6$ suggests that several episodes of moderate super-Eddington accretion occur and each of them lasts for $τ\simeq 20-30$ Myr. The average duty cycle in super-Eddington phases is $\simeq 15\%$ for massive BHs that reach $\gtrsim 10^8~M_\odot$ by $z\simeq 6$, which is nearly twice that of the entire population. We also find that the observed Eddington-ratio distribution function is skewed to a log-normal shape owing to detection limits of quasar surveys. The predicted redshift evolution of the QLF and BHMF suggests a rapid decay of their number and mass density in a cosmic volume toward $z\gtrsim 6$. These results will be unveiled by future deep and wide surveys with the James Webb Space Telescope, Roman Space Telescope, and Euclid.

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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