| Title: |
Black Hole Mass and Eddington-ratio Distributions of Less-luminous Quasars at z ∼ 4 in the Subaru Hyper Suprime-Cam Wide Field |
| Authors: |
Wanqiu He, Masayuki Akiyama, Motohiro Enoki, Kohei Ichikawa, Kohei Inayoshi, Nobunari Kashikawa, Toshihiro Kawaguchi, Yoshiki Matsuoka, Tohru Nagao, Masafusa Onoue, Taira Oogi, Andreas Schulze, Yoshiki Toba, Yoshihiro Ueda |
| Source: |
The Astrophysical Journal, Vol 962, Iss 2, p 152 (2024) |
| Publisher Information: |
IOP Publishing, 2024. |
| Publication Year: |
2024 |
| Collection: |
LCC:Astrophysics |
| Subject Terms: |
Supermassive black holes, Galaxy evolution, High-redshift galaxies, Active galaxies, Astrophysics, QB460-466 |
| More Details: |
We investigate the black hole mass function (BHMF) and Eddington-ratio distribution function (ERDF) of broad-line active galactic nuclei (AGNs) at z = 4, based on a sample of 52 quasars with i < 23.2 at 3.50 ≤ z ≤ 4.25 from the Hyper Suprime-Cam Subaru Strategic Program S16A-Wide2 data set, and 1462 quasars with i < 20.2 in the same redshift range from the Sloan Digital Sky Survey data release 7 quasar catalog. Virial black hole (BH) masses of quasars are estimated using the width of the C _IV 1549 Å line and the continuum luminosity at 1350 Å. To obtain the intrinsic broad-line AGN BHMF and ERDF, we correct for the incompleteness in the low-mass and/or low-Eddington-ratio ranges caused by the flux-limited selection. The resulting BHMF is constrained down to $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }\sim 7.5$ . In comparison with broad-line AGN BHMFs at z ∼ 2 in the literature, we find that the number density of massive SMBHs peaks at higher redshifts, consistent with the downsizing evolutionary scenario. Additionally, the resulting ERDF shows a negative dependence on BH mass, suggesting more massive SMBHs tend to accrete at lower-Eddington ratios at z = 4. With the derived intrinsic broad-line AGN BHMF, we also evaluate the active fraction of broad-line AGNs among the entire SMBH population at z = 4. The resulting active fraction may suggest a positive dependence on BH mass. Finally, we examine the time evolution of broad-line AGN BHMF between z = 4 and 6 through solving the continuity equation. The results suggest that the broad-line AGN BHMFs at z = 4–6 only show evolution in their normalization, but with no significant changes in their shape. |
| Document Type: |
article |
| File Description: |
electronic resource |
| Language: |
English |
| ISSN: |
1538-4357 |
| Relation: |
https://doaj.org/toc/1538-4357 |
| DOI: |
10.3847/1538-4357/ad1518 |
| Access URL: |
https://doaj.org/article/39821e42972f411daa82afbfa89a8b69 |
| Accession Number: |
edsdoj.39821e42972f411daa82afbfa89a8b69 |
| Database: |
Directory of Open Access Journals |
