f(R)引力中小红点的原初黑洞种子
Primordial Black Hole Seeds for Little Red Dots in $f(R)$ Gravity
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中文总结 AI 辅助
本研究在Hu-Sawicki f(R)引力框架下，提出原初黑洞并合形成中等质量种子黑洞的混合组装框架，可解释JWST观测到的高红移小红点，且符合相关观测限制，还能通过多信使诊断打破参数简并。
中文摘要 AI 辅助
詹姆斯·韦布空间望远镜（JWST）发现高红移处存在大量致密的小红点（LRD）和超大质量黑洞，这对标准的恒星级遗迹爱丁顿极限增长模型构成了严重的时间挑战。本研究提出了一个统一的混合组装框架：在Hu-Sawicki f(R)引力理论中，中等质量种子黑洞通过致密星团内的层级式原初黑洞（PBH）并合形成，随后吸积星系气体。研究表明，被屏蔽的f(R)第五力通过引力波辐射捕获核的二次增强，非线性加速早期种子的形成，而环境变色龙屏蔽则动态自我调节增长。由于后续气体吸积与种子质量呈乘法比例，f(R)带来的种子增强在整个吸积历史中得以保留，大幅降低了宇宙黎明时组装出10^6-10^9倍太阳质量LRD所需的时间平均爱丁顿比。将本研究的活动质量函数与JWST观测数据对比发现，在真实的活动星系核占空比（δ≈10^-2）下，少量成团的PBH占比（f_PBH≲10^-3）可自然匹配z~5.5-6.5处观测到的LRD空间密度，同时完全符合LIGO-Virgo-KAGRA的限制，而修正引力则自然驱动了高质量端的分布。最后，研究显示，结合三类多信使诊断手段可清晰打破修正引力与星团密度之间的参数简并：遗迹自旋态特征、随机引力波背景截断以及PBH空间关联函数的尺度依赖反转。
英文摘要
The discovery by the James Webb Space Telescope (JWST) of an abundant population of compact little red dots (LRDs) and supermassive black holes at high redshifts poses a severe timing challenge for standard Eddington-limited growth from stellar remnants. In this work, we present a unified hybrid assembly framework in which intermediate-mass seed black holes are formed via hierarchical primordial black hole (PBH) mergers within dense clusters in Hu-Sawicki $f(R)$ gravity, followed by galactic gas accretion. We demonstrate that the screened $f(R)$ fifth force nonlinearly accelerates early seed formation through a quadratic enhancement of the gravitational-wave radiation-capture kernel, while environmental chameleon screening dynamically self-regulates the growth. Because subsequent gas accretion scales multiplicatively with seed mass, the $f(R)$ seed enhancement is preserved throughout the accretion history, drastically reducing the time-averaged Eddington ratios required to assemble $10^{6}\text{-}10^{9}\,M_{\odot}$ LRDs by cosmic dawn. Confronting our active mass functions with JWST data reveals that a small clustered PBH fraction ($f_{\rm PBH} \lesssim 10^{-3}$) under a realistic active galactic nucleus duty cycle ($δ\approx 10^{-2}$) naturally matches observed LRD space densities at $z \sim 5.5\text{-}6.5$ while remaining fully compliant with LIGO-Virgo-KAGRA limits, with modified gravity naturally driving the high-mass tail. Finally, we show that parameter degeneracies between modified gravity and cluster density can be cleanly broken by combining three multi-messenger diagnostics: remnant spin state signatures, a stochastic GW background cutoff, and a scale-dependent inversion in the PBH spatial correlation function.
发表机构
- Universitat de València（瓦伦西亚大学）
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