期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 449, 期 1, 页码 559-573出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stv078
关键词
galaxies: active; galaxies: evolution; galaxies: statistics; galaxies: stellar content
资金
- CAPES-COFECUB [30007ZD]
- CAPES
- FAPESP
- CAPES/PDSE-BEX [8509/11-5]
- LUTH, at Observatoire de Paris
- Brazilian agency FAPESP [2009/54006-4]
- INCT-A
- Alfred P. Sloan Foundation
- National Science Foundation
- US Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- University of Cambridge
- Case Western Reserve University
- University of Chicago
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck-Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- Ohio State University
- University of Pittsburgh
- University of Portsmouth
- Princeton University
- United States Naval Observatory
- University of Washington
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [09/54006-4] Funding Source: FAPESP
We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with M-* > 10(11.5) M-circle dot have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than 10(10)M(circle dot). We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments - i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1-5 Gyr for detectable AGN in galaxies with masses between 10(10)-10(12) M-circle dot. The lifetimes of the AGN-dominated phases are a few 10(8) yr. Finally, we compare the star formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on, it inhibits star formation for the next similar to 0.1 Gyr in galaxies with masses around 10(10)M(circle dot), similar to 1 Gyr in galaxies with masses around 10(11) M-circle dot.
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