期刊
ASTROPHYSICAL JOURNAL
卷 761, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/761/2/143
关键词
galaxies: active; galaxies: evolution; galaxies: statistics; quasars: emission lines; quasars: general
资金
- JSPS [18740118, 21340042]
- Grants-in-Aid for Scientific Research [21340042, 24103003, 24650145, 23540265, 18740118, 24540230, 22340044] Funding Source: KAKEN
- STFC [ST/G004331/1, PP/E003427/1, ST/H002456/1, PP/E001149/1, ST/H002391/1, ST/H001972/1, ST/I003673/1, ST/J001465/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/I003673/1, ST/H001972/1, ST/J001465/1, ST/G004331/1, ST/H002456/1, PP/E001149/1, PP/E003427/1, ST/H002391/1] Funding Source: researchfish
- UK Space Agency [ST/J004669/1] Funding Source: researchfish
In order to investigate the growth of supermassive black holes (SMBHs), we construct the black hole mass function (BHMF) and Eddington ratio distribution function (ERDF) of X-ray-selected broad-line active galactic nuclei (AGNs) at z similar to 1.4 in the Subaru XMM-Newton Deep Survey (SXDS) field. A significant part of the accretion growth of SMBHs is thought to take place in this redshift range. Black hole masses of X-ray-selected broad-line AGNs are estimated using the width of the broad Mg II line and 3000 angstrom monochromatic luminosity. We supplement the Mg II FWHM values with the H alpha FWHM obtained from our NIR spectroscopic survey. Using the black hole masses of broad-line AGNs at redshifts between 1.18 and 1.68, the binned broad-line AGN BHMFs and ERDFs are calculated using the V-max method. To properly account for selection effects that impact the binned estimates, we derive the corrected broad-line AGN BHMFs and ERDFs by applying the maximum likelihood method, assuming that the ERDF is constant regardless of the black hole mass. We do not correct for the non-negligible uncertainties in virial BH mass estimates. If we compare the corrected broad-line AGN BHMF with that in the local universe, then the corrected BHMF at z = 1.4 has a higher number density above 10(8) M-circle dot but a lower number density below that mass range. The evolution may be indicative of a downsizing trend of accretion activity among the SMBH population. The evolution of broad-line AGN ERDFs from z = 1.4 to 0 indicates that the fraction of broad-line AGNs with accretion rates close to the Eddington limit is higher at higher redshifts.
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