Population III star formation in an X-ray background: III. Periodic radiative feedback and luminosity induced by elliptical orbits
Population III star formation in an X-ray background: III. Periodic radiative feedback and luminosity induced by elliptical orbits
复制标题
X 射线背景中的 III 族恒星形成：III。
DOI：
10.1093/mnras/stad895
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发表时间：
2023
影响因子：
4.8
通讯作者：
Sugimura Kazuyuki
中科院分区：
文献类型：
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作者：
Park Jongwon;Ricotti Massimo;Sugimura Kazuyuki
我们模型Pop III星星形成在不同的FUV和X射线背景，包括辐射反馈的原恒星。我们证实了以前的结果，一个温和的X射线背景增加了每单位宇宙体积的波普III系统的数量，但质量和系统的多重性减少。恒星的质量函数也同意与以前的结果，我们确认向外迁移的恒星内的原恒星盘。我们发现，几乎所有的波普III星星系统是分层的，即二进制的二进制。通常情况下，两颗质量相等的恒星在原恒星盘的中心附近形成，并向外迁移。在这些恒星周围，迷你盘碎片形成的双星也向外迁移。恒星也可能在系统的拉格朗日点L4/L5形成。之后，星星的形成变得更加随机，由于大的多重性，零金属量的低质量恒星可以形成时，迅速从光盘。盘中的恒星通常有偏心轨道，导致其吸积率和光度的周期性调制。在近心点，由于强烈的吸积作用，星星可以进入红超巨星阶段，在光学波段达到接近爱丁顿光度（100 M星星在z = 6时的mAB为34）。在这个阶段，如果用引力透镜充分放大，JWST可以直接观测到星星，而不是星云线。在我们的模拟中，许多Pop III型星星双星的10000 Au间距和高偏心率是通过场星的轨道激发进行IMBH合并和引力波发射的有利参数。
We model Pop III star formation in different FUV and X-ray backgrounds, including radiation feedback from protostars. We confirm previous results that a moderate X-ray background increases the number of Pop III systems per unit cosmological volume, but masses and multiplicities of the system are reduced. The stellar mass function also agrees with previous results, and we confirm the outward migration of the stars within the protostellar discs. We find that nearly all Pop III star systems are hierarchical, i.e. binaries of binaries. Typically, two equal-mass stars form near the centre of the protostellar disc and migrate outwards. Around these stars, mini-discs fragment forming binaries that also migrate outwards. Stars may also form at Lagrange points L4/L5 of the system. Afterwards, star formation becomes more stochastic due to the large multiplicity, and zero-metallicity low-mass stars can form when rapidly ejected from the disc. Stars in the disc often have eccentric orbits, leading to a periodic modulation of their accretion rates and luminosities. At the pericentre, due to strong accretion, the star can enter a red-supergiant phase reaching nearly Eddington luminosity in the optical bands (mAB∼ 34 for a 100 M⊙star at z = 6). During this phase, the star, rather than its nebular lines, can be observed directly byJWST, if sufficiently magnified by a gravitational lens. The ∼10 000 AU separations and high eccentricities of many Pop III star binaries in our simulations are favourable parameters for IMBH mergers – and gravitational waves emission – through orbital excitation by field stars.