期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 721, 期 1, 页码 L1-L5出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/721/1/L1
关键词
dark matter; gravitational lensing: strong
资金
- Swiss National Science Foundation
- National Science Foundation [AST-0808099, AST-0909237]
- Directorate For Geosciences
- Div Atmospheric & Geospace Sciences [0752135] Funding Source: National Science Foundation
We analyze the correlations between central dark matter (DM) content of early-type galaxies and their sizes and ages, using a sample of intermediate-redshift (z similar to 0.2) gravitational lenses from the SLACS survey, and by comparing them to a larger sample of z similar to 0 galaxies. We decompose the deprojected galaxy masses into DM and stellar components using combinations of strong lensing, stellar dynamics, and stellar populations modeling. For a given stellar mass, we find that for galaxies with larger sizes, the DM fraction increases and the mean DM density decreases, consistently with the cuspy halos expected in cosmological formation scenarios. The DM fraction also decreases with stellar age, which can be partially explained by the inverse correlation between size and age. The residual trend may point to systematic dependencies on formation epoch of halo contraction or stellar initial mass functions. These results are in agreement with recent findings based on local galaxies by Napolitano et al. and suggest negligible evidence of galaxy evolution over the last similar to 2.5 Gyr other than passive stellar aging.
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