Affiliation: ISAS/JAXA
Contribution: Poster
Title: Deep Search for Low-mass SMBH at intermediate/high redshift
Abstract: It is an important astrophysical question how SMBH have been developed in the hierarchical growth of galaxies. One of the most remarkable discovery with JWST is the detection of SMBH with 10^6-10^8 Msun SMBH at very high redshift, many of which show over-massive nature compared with the tight BH-stellar mass correlation observed in the local galaxies. While the complete picture of SMBH and AGN population at z>5 is still to be unveiled, the sample of such low-mass SMBH even at intermediate redshift (z~1-4) is also still very limited. In this poster we report the results of the study of BH and galaxy mass relationship (Hoshi et al. 2024) based on the deep multi-color variability search using the Subaru HSC Ultradeep Survey in the COSMOS filed (Kimura et al. 2020). Variability search has an advantage in detecting type-1 AGN, which is needed to obtain BH mass by the single-epoch virial method using the broad-line width. By analyzing the available spectra, we obtained BH mass of ~200 objects down to 1×10^7 Msun at z~2, including several objects below 10^7 Msun at z=0.5-1.5. We also obtained the host galaxy stellar mass for ~120 objects by SED fitting analysis with AGN and galaxy templates. While a half the massive BH above 10^9 Msun at intermediate redshift shows over-massive nature, BH with 10^7 -10^9Msun has the similar or only very mildly evolving value of M_BH/M_stellar ratio. We discuss the possible scenario of the BH growth in the universe. For the future prospects, it is clear to need more systematic study for low-mass BH and galaxies at intermediate/high redshift. High Latitude Time Domain Survey planned for Nancy Grace Roman space telescope will provide an ideal very powerful dataset for the systematic variability search for the low-luminosity AGN. We also describe the prospects and a proposed plan for AGN variability search with Roman.
This contribution can be found in the Poster Hall.