通过JWST/RST探测潮汐瓦解事件以研究早期大质量黑洞的质量函数
Probing the mass function of early massive black holes through detecting tidal disruption events with JWST/RST
The mass distribution function of massive black holes (BHs) at high redshifts encodes key information on their growth via accretion. Our current understanding of quasar populations at z>4 significantly benefits from wide-field surveys with ground-based telescopes (e.g., the Sloan Digital Sky Survey). Recently, the unprecedented sensitivity of the James Webb Space Telescope (JWST) has enabled the discovery of low-luminosity active galactic nuclei (AGNs) at z~4-7, which were hidden in the pre-JWST era. Spectroscopic follow-up observations have provided estimates of the nuclear BH masses for these sources and pushed the low-mass boundary down to ~10^{6-7} Msun. Although this breakthrough has brought us useful insights into their formation process, the ‘observed’ lowest mass of BHs is still >1-2 orders of magnitude heavier than the typical mass of seed BHs, and thus the mass distribution shape remains poorly constrained. In this talk, as a tool for unveiling the presence of low mass BH populations at such high redshifts, I consider UV/optical (in rest frame) flares of stellar tidal disruption events (TDEs) caused by ~10^{5-7} Msun BHs embedded in low-luminosity AGNs. I give a simple derivation of the TDE rate based on the AGN host galaxy properties inferred from JWST observations and discuss the realistic/optimistic survey strategies to hunt for the transient high-redshift TDEs with the ongoing JWST and forthcoming Roman Space Telescope surveys.
