期刊
ASTROPHYSICAL JOURNAL
卷 808, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/808/1/26
关键词
galaxies: abundances; galaxies: evolution
资金
- Alfred P. Sloan Foundation
- Participating Institutions
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1211644] Funding Source: National Science Foundation
We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption-line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data cover. the central regions of these galaxies, out to slightly higher than 1R(e). We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. The gradients are only weakly dependent on stellar mass, and this dependence is well. correlated with the change of R-e with mass. Based on these data, we report mean equivalent widths, metallicities, and abundance ratios as a function of mass and velocity dispersion for SDSS early-type galaxies, for fixed apertures of 2.5 kpc and of 0.5R(e).
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