A calibration of the stellar-mass fundamental plane at <z> = 0.5 using the micro-lensing induced flux ratio anomalies of macro-lensed quasars

Paul Schechter (MIT)
Event Date and Time: 
Mon, 2015-03-23 15:30 - 16:30
Hennings 318
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 ten 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 IMF with a low mass
cutoff of 0.1 solar masses 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 < F < 2.10.
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