{"title":"Early black-hole seeds in the first billion years","authors":"U. Maio","doi":"10.22323/1.362.0014","DOIUrl":null,"url":null,"abstract":"Supermassive black holes with billion solar masses are in place already within the first Gyr, however, their origin and growth in such a short lapse of time is extremely challenging to understand. Here, we discuss the formation paths of early black-hole seeds, showing the limits of light black-hole seeds from stellar origin and the expected characteristics of heavy/massive black-hole seeds originated by gas direct collapse in peculiar primordial conditions. To draw conclusions on the possible candidates and the role of the ambient medium, we use results from N-body hydrodynamic simulations including atomic and molecular non-equilibrium abundance calculations, cooling, star formation, feedback mechanisms, stellar evolution, metal spreading of several heavy elements from SNII, AGB and SNIa, and multifrequency radiative transfer over 150 frequencies coupled to chemistry and SED emission for popII-I and popIII stellar sources. Standard stellar-origin light black holes are unlikely to be reliable seeds of early supermassive black holes, because, under realistic assumptions, they cannot grow significantly in less than a billion years. Alternatively, massive black-hole seeds might originate from direct collapse of pristine gas in primordial quiescent mini-haloes that are exposed to stellar radiation from nearby star forming regions. The necessary conditions required to form these heavy seeds must be complemented with information on the complex features of local environments and the fine balance between chemistry evolution and radiative transfer.","PeriodicalId":265862,"journal":{"name":"Proceedings of Multifrequency Behaviour of High Energy Cosmic Sources - XIII — PoS(MULTIF2019)","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2019-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of Multifrequency Behaviour of High Energy Cosmic Sources - XIII — PoS(MULTIF2019)","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.22323/1.362.0014","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 1
Abstract
Supermassive black holes with billion solar masses are in place already within the first Gyr, however, their origin and growth in such a short lapse of time is extremely challenging to understand. Here, we discuss the formation paths of early black-hole seeds, showing the limits of light black-hole seeds from stellar origin and the expected characteristics of heavy/massive black-hole seeds originated by gas direct collapse in peculiar primordial conditions. To draw conclusions on the possible candidates and the role of the ambient medium, we use results from N-body hydrodynamic simulations including atomic and molecular non-equilibrium abundance calculations, cooling, star formation, feedback mechanisms, stellar evolution, metal spreading of several heavy elements from SNII, AGB and SNIa, and multifrequency radiative transfer over 150 frequencies coupled to chemistry and SED emission for popII-I and popIII stellar sources. Standard stellar-origin light black holes are unlikely to be reliable seeds of early supermassive black holes, because, under realistic assumptions, they cannot grow significantly in less than a billion years. Alternatively, massive black-hole seeds might originate from direct collapse of pristine gas in primordial quiescent mini-haloes that are exposed to stellar radiation from nearby star forming regions. The necessary conditions required to form these heavy seeds must be complemented with information on the complex features of local environments and the fine balance between chemistry evolution and radiative transfer.
在第一Gyr中已经有了数十亿太阳质量的超大质量黑洞,然而,它们在如此短的时间内的起源和增长是极具挑战性的。在这里,我们讨论了早期黑洞种子的形成路径,显示了来自恒星起源的轻黑洞种子的局限性以及在特殊原始条件下由气体直接坍缩产生的重/大质量黑洞种子的预期特征。为了得出可能的候选物质和环境介质的作用,我们使用了n体流体动力学模拟的结果,包括原子和分子非平衡丰度计算、冷却、恒星形成、反馈机制、恒星演化、SNII、AGB和SNIa中几种重元素的金属扩散,以及popi - i - i和popIII恒星源的150多个频率的多频辐射传输,以及化学和SED发射。标准恒星起源的光黑洞不太可能是早期超大质量黑洞的可靠种子,因为在现实的假设下,它们不可能在不到10亿年的时间里显著增长。另一种说法是,大质量黑洞的种子可能起源于原始静止微晕中原始气体的直接坍缩,这些微晕暴露在附近恒星形成区域的恒星辐射中。形成这些重种子所需的必要条件必须辅以有关当地环境的复杂特征和化学演化与辐射转移之间的微妙平衡的信息。