A Calibration of the Stellar Mass Fundamental Plane at z ~ 0.5 Using the Micro-lensing-induced Flux Ratio Anomalies of Macro-lensed Quasars
Abstract
We measure the stellar mass surface densities of early-type galaxies by observing the micro-lensing of macro-lensed quasars caused by individual stars, including stellar remnants, brown dwarfs, and red dwarfs too faint to produce photometric or spectroscopic signatures. Instead of observing multiple micro-lensing events in a single system, we combine single-epoch X-ray snapshots of 10 quadruple systems, and compare the measured relative magnifications for the images with those computed from macro-models. We use these to normalize a stellar mass fundamental plane constructed using a Salpeter initial mass function with a low-mass cutoff of 0.1 M ⊙ and treat the zeropoint of the surface mass density as a free parameter. Our method measures the graininess of the gravitational potential produced by individual stars, in contrast to methods that decompose a smooth total gravitational potential into two smooth components, one stellar and one dark. We find the median likelihood value for the normalization factor F by which the Salpeter stellar masses must be multiplied is 1.23, with a one sigma confidence range, dominated by small number statistics, of 0.77 .
Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO-9854.- Publication:
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The Astrophysical Journal
- Pub Date:
- October 2014
- DOI:
- 10.1088/0004-637X/793/2/96
- arXiv:
- arXiv:1405.0038
- Bibcode:
- 2014ApJ...793...96S
- Keywords:
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- galaxies: stellar content;
- gravitational lensing: micro;
- gravitational lensing: strong;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Revised in response to referee's suggestions and re-submitted to ApJ