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Black Holes Grow More Efficiently in Massive Galaxies |
Seminar Title | Black Holes Grow More Efficiently in Massive Galaxies | | | Speaker: | Dr. YANG Guang | | | Affiliation: | ( HUST) | | | When | Tuesday afternoon , Dec. 20 , 14:00 p.m | | | Where: | Room 416, Office Block, 2 West Beijing Road (PMO, CAS) | | Welcome to Attend | | | ( PMO Academic Committee & Academic Circulating committee) | | Abstract: The potential coevolution between supermassive black holes (SMBHs) and their host galaxies remains a fundamental problem.In the local universe, the proportionality between SMBH mass and stellar mass of host galaxies provides a strong support for coevolution. Observations of distant star-forming galaxies reveal a tight linear correlation between star formation rate (SFR) and sample-average black-hole accretion rate (BHAR). However, for the host galaxies of X-ray selected AGNs, the SFR is flat as a function of BHAR except at high X-ray luminosities. To reconcile the apparent discrepancy, a recent study advanced a coevolution model assuming that SFR is proportional to long-term average BHAR (average over ~100 Myr), but shorter-term variability has obscured the BHAR-SFR relation.This model is capable in explaining almost all the observational facts so far. We verifythis simple coevolution scenario by studying BHAR dependence on SFR and stellar mass (M_*) of host galaxies. Our study is based on the 7 Ms Chandra Deep Field-South (CDF-S) survey, the deepest X-ray survey, which is available recently. We find that SFR alone is not an adequate tracer of long-term average BHAR. Massive galaxies (M_*>10^10 M_sun) have higher ratios of BHAR/SFR than their less-massive counterparts, indicating that their SMBHs grow more efficiently. |
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Copyright? Purple Mountain Observatory, CAS, No.10 Yuanhua Road, Qixia District, Nanjing 210023, China
Phone: 0086 25 8333 2000 Fax: 8333 2091 http://english.pmo.cas.cn |
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