标准紫外连续谱可以隐藏GN-z11中的超临界吸积
A Standard Ultraviolet Continuum Can Hide Supercritical Accretion in GN-z11
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中文总结 AI 辅助
本文发现标准紫外连续谱拟合可能高估GN-z11等高红移黑洞质量，超临界吸积可隐藏其中，提出判据并修正质量约束，影响早期黑洞形成模型。
中文摘要 AI 辅助
高红移吸积黑洞的紫外连续谱通常被用来推断其质量。GN-z11为这一推断是否可靠提供了一个尖锐的检验。对其连续谱的薄盘拟合给出的爱丁顿质量为$M_{\rm E}=1.12\times10^{7}\\,\Msun$，比从宽N~\textsc{iv}推断出的$\log(\Mbh/\Msun)=6.2\pm0.3$高出一个数量级。我们表明，这种明显的矛盾并非仅由紫外斜率造成。我们推导出一个闭式判据，比较观测光子产生的半径与超临界流偏离有效解处的半径。对于GN-z11，该判据将超临界转变置于紫外辐射区域内部。保留外部解的复合盘模型在数值上证实了这一点，要求$\Mdot_{\rm out}=3.1$--$4.4\\,\Msun\\,\mathrm{yr^{-1}}$，并将$\Rsph=(1.2$--$1.8)\times10^{3}\\,\rg$置于$\Ruv=(2.6$--$2.9)\times10^{3}\\,\rg$内部。将内部约$10^{3}\\,\rg$替换为超临界流仅使拟合斜率改变$\Delta\betaUV=+0.08$至$+0.11$，与标准光谱建模的不确定性相当。反转径向顺序需要有效转变向外移动$1.7$--$2.1$倍。在我们的复合模型中，测量到的斜率仅将黑洞质量约束在约$10^{6}\\,\Msun$，比连续谱爱丁顿质量低一个数量级。因此，连续谱爱丁顿质量应被视为依赖于模型的界限，其假设了全局薄盘效率。在盘主导解释下，同样的层级出现在另外三个JWST源中，其分离质量仅为连续谱爱丁顿质量的$4$--$6$\\%。这种区分可以显著削弱从宇宙黎明时期紫外连续谱推断出的首批大质量黑洞的种子质量和早期增长要求。
英文摘要
The ultraviolet continuum from a high-redshift accreting black hole is routinely used to infer its mass. GN-z11 offers a sharp test of whether that inference is secure. A thin-disk fit to its continuum gives an Eddington mass of $M_{\rm E}=1.12\times10^{7}\,\Msun$, an order of magnitude above the $\log(\Mbh/\Msun)=6.2\pm0.3$ inferred from broad N~\textsc{iv}. We show that this apparent tension is not imposed by the ultraviolet slope alone. We derive a closed-form criterion comparing the radius where observed photons are produced with the radius where a supercritical flow departs from efficient solution. For GN-z11, the criterion places the supercritical transition inside the ultraviolet-emitting region. Composite disks retaining the outer solution confirm this numerically, requiring $\Mdot_{\rm out}=3.1$--$4.4\,\Msun\,\mathrm{yr^{-1}}$ and placing $\Rsph=(1.2$--$1.8)\times10^{3}\,\rg$ inside $\Ruv=(2.6$--$2.9)\times10^{3}\,\rg$. Replacing the inner $\sim10^{3}\rg$ by a supercritical flow shifts the fitted slope by only $Δ\betaUV=+0.08$ to $+0.11$, comparable to uncertainties from standard spectral modelling. Reversing the radial ordering requires the effective transition to move outward by a factor $1.7$--$2.1$. Within our composite models, the measured slope constrains black-hole mass only to around $10^{6}\,\Msun$, an order of magnitude below the continuum Eddington mass. Continuum Eddington masses should therefore be treated as model-dependent bounds that assume global thin-disk efficiency. The same hierarchy appears in three additional JWST sources under the disk-dominated interpretation, where separation masses are only $4$--$6$\% of continuum Eddington masses. This distinction can substantially weaken the seed-mass and early-growth demands inferred from ultraviolet continua at cosmic dawn for the first massive black holes.
发表机构
- International Centre for Theoretical Sciences, Tata Institute of Fundamental Research（国际理论科学中心，塔塔基础研究所）
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