H I-SELECTED GALAXIES IN THE SLOAN DIGITAL SKY SURVEY. II. THE COLORS OF GAS-RICH GALAXIES
- MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-582c, Cambridge, MA 02139-4307 (United States)
- European Southern Observatory, Alonso de Cordova 3107, Casilla 19001, Vitacura, Santiago 19 (Chile)
- Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)
- Cardiff School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom)
We utilize color information for an H I-selected sample of 195 galaxies to explore the star formation histories and physical conditions that produce the observed colors. We show that the H I selection creates a significant offset toward bluer colors that can be explained by enhanced recent bursts of star formation. There is also no obvious color bimodality, because the H I selection restricts the sample to bluer, actively star-forming systems, diminishing the importance of the red sequence. Rising star formation rates are still required to explain the colors of galaxies bluer than g - r< 0.3. We also demonstrate that the colors of the bluest galaxies in our sample are dominated by emission lines and that stellar population synthesis models alone (without emission lines) are not adequate for reproducing many of the galaxy colors. These emission lines produce large changes in the r - i colors but leave the g - r color largely unchanged. In addition, we find an increase in the dispersion of galaxy colors at low masses that may be the result of a change in the star formation process in low-mass galaxies.
- OSTI ID:
- 21301640
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 138, Issue 3; Other Information: DOI: 10.1088/0004-6256/138/3/796; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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