TY - JOUR
T1 - Stellar mass estimates in early-type galaxies from lensing+dynamical and photometric measurements
AU - Grillo, C.
AU - Gobat, R.
AU - Rosati, P.
AU - Lombardi, M.
PY - 2008/1
Y1 - 2008/1
N2 - Aims. Our purpose is to compare two different diagnostics for estimating stellar masses in early-type galaxies and to establish their level of reliability. In particular, we consider the well-studied sample of 15 field elliptical galaxies selected, from, the Sloan Lens ACS (SLACS) Survey (z = 0.06-0.33). We examine here the correlation between the stellar mass values, enclosed inside the Einstein radius (REin) of each lens, based on analyses of lensing and stellar dynamics combined and based on multiwavelength photometry spectral template fitting. Methods. The lensing+dynamics stellar mass Mlen+dyn(≤REin) is obtained from the published SLACS Survey results, assuming a two-component density distribution model and a prior from the fundamental plane on the mass-to-light ratio for the lens galaxies. The photometric stellar mass Mphot(≤REin) is measured by fitting the observed spectral energy distribution of the galaxies (from the SDSS multi-band photometry over 354-913 nm) with composite stellar population templates, under the assumption that light traces stellar mass. Results. The two methods are completely independent. They rely on several different assumptions, and so, in principle, both can have significant biases. Based on our sample of massive galaxies (log Mphot(≤REin) $sime; [10.3, 11.5]), we find consistency between the values of M Len-dyn(≤REin) and Mphot(≤R Ein). We obtain a Pearson linear correlation coefficient of 0.94 and a median value of the ratio between the former and the latter mass measurements of 1.1 ±0.1. This suggests that both methods can separately yield reliable stellar masses of early-type galaxies, and confirms that photometric mass estimates are accurate, as long as optical/near-IR rest frame photometry is available.
AB - Aims. Our purpose is to compare two different diagnostics for estimating stellar masses in early-type galaxies and to establish their level of reliability. In particular, we consider the well-studied sample of 15 field elliptical galaxies selected, from, the Sloan Lens ACS (SLACS) Survey (z = 0.06-0.33). We examine here the correlation between the stellar mass values, enclosed inside the Einstein radius (REin) of each lens, based on analyses of lensing and stellar dynamics combined and based on multiwavelength photometry spectral template fitting. Methods. The lensing+dynamics stellar mass Mlen+dyn(≤REin) is obtained from the published SLACS Survey results, assuming a two-component density distribution model and a prior from the fundamental plane on the mass-to-light ratio for the lens galaxies. The photometric stellar mass Mphot(≤REin) is measured by fitting the observed spectral energy distribution of the galaxies (from the SDSS multi-band photometry over 354-913 nm) with composite stellar population templates, under the assumption that light traces stellar mass. Results. The two methods are completely independent. They rely on several different assumptions, and so, in principle, both can have significant biases. Based on our sample of massive galaxies (log Mphot(≤REin) $sime; [10.3, 11.5]), we find consistency between the values of M Len-dyn(≤REin) and Mphot(≤R Ein). We obtain a Pearson linear correlation coefficient of 0.94 and a median value of the ratio between the former and the latter mass measurements of 1.1 ±0.1. This suggests that both methods can separately yield reliable stellar masses of early-type galaxies, and confirms that photometric mass estimates are accurate, as long as optical/near-IR rest frame photometry is available.
KW - Cosmology: observations
KW - Galaxies: elliptical and lenticular, cD
KW - Galaxies: evolution
KW - Galaxy: formation
KW - Galaxy: kinematics and dynamics
KW - Gravitational lensing
UR - http://www.scopus.com/inward/record.url?scp=38349141872&partnerID=8YFLogxK
U2 - 10.1051/0004-6361:20078934
DO - 10.1051/0004-6361:20078934
M3 - Article
AN - SCOPUS:38349141872
VL - 477
SP - L25-L28
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
IS - 2
ER -