COSMIC EVOLUTION OF VIRIAL AND STELLAR MASS IN MASSIVE EARLY-TYPE GALAXIES

Journal Article · Sun Jun 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/716/2/1579· OSTI ID:21452907

Lagattuta, David J; Fassnacht, Christopher D; Auger, Matthew W ^[1]; Marshall, Philip J; Bradac, Marusa; Treu, Tommaso ^[2]; Gavazzi, Raphael ^[3]; Schrabback, Tim ^[4]; Faure, Cecile ^[5]; Anguita, Timo ^[6]

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1. Department of Physics, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 (United States)
2. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
3. Institut d'Astrophysique de Paris, CNRS UMR 7095 and Univ. Paris 6, 98bis Bd Arago, 75014 Paris (France)
4. Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333CA Leiden (Netherlands)
5. Laboratoire d'Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix (Switzerland)
6. Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstr. 12-14, 69120 Heidelberg (Germany)

We measure the average mass properties of a sample of 41 strong gravitational lenses at moderate redshift (z {approx} 0.4-0.9) and present the lens redshift for six of these galaxies for the first time. Using the techniques of strong and weak gravitational lensing on archival data obtained from the Hubble Space Telescope, we determine that the average mass overdensity profile of the lenses can be fit with a power-law profile ({Delta}{Sigma} {proportional_to} R {sup -0.86{+-}0.16}) that is within 1{sigma} of an isothermal profile ({Delta}{Sigma} {proportional_to} R {sup -1}) with velocity dispersion {sigma}{sub v} = 260 {+-} 20 km s{sup -1}. Additionally, we use a two-component de Vaucouleurs + Navarro-Frenk-White (NFW) model to disentangle the total mass profile into separate luminous and dark matter components and determine the relative fraction of each component. We measure the average rest frame V-band stellar mass-to-light ratio (Y{sub V} = 4.0 {+-} 0.6 h M{sub sun}/L{sub sun}) and virial mass-to-light ratio ({tau}{sub V} = 300 {+-} 90 h M{sub sun}/L{sub sun}) for our sample, resulting in a virial-to-stellar mass ratio of M{sub vir}/M{sub *} = 75 {+-} 25. Relaxing the NFW assumption, we estimate that changing the inner slope of the dark matter profile by {approx}20% yields a {approx}30% change in stellar mass-to-light ratio. Finally, we compare our results to a previous study using low-redshift lenses to understand how galaxy mass profiles evolve over time. We investigate the evolution of M{sub vir}/M{sub *}(z) = {alpha}(1 + z){sup {beta}}, and find best-fit parameters of {alpha} = 51 {+-} 36 and {beta} = 0.9 {+-} 1.8, constraining the growth of virial-to-stellar mass ratio over the last {approx}7 Gyr. We note that, by using a sample of strong lenses, we are able to constrain the growth of M{sub vir}/M{sub *}(z) without making any assumptions about the initial mass function of the stellar population.

• OSTI ID: 21452907
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 716; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
GRAVITATIONAL LENSES
LENSES
MASS
MATTER
NONLUMINOUS MATTER
RED SHIFT
TELESCOPES