Bibcode
Courbin, F.; Chantry, V.; Revaz, Y.; Sluse, D.; Faure, C.; Tewes, M.; Eulaers, E.; Koleva, M.; Asfandiyarov, I.; Dye, S.; Magain, P.; van Winckel, H.; Coles, J.; Saha, P.; Ibrahimov, M.; Meylan, G.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 536, id.A53
Advertised on:
12
2011
Revista
Número de citas
107
Número de citas referidas
98
Descripción
We present accurate time delays for the quadruply imaged quasar HE
0435-1223. The delays were measured from 575 independent photometric
points obtained in the R-band between January 2004 and March 2010. With
seven years of data, we clearly show that quasar image A is affected by
strong microlensing variations and that the time delays are best
expressed relative to quasar image B. We measured ΔtBC
= 7.8 ± 0.8 days, ΔtBD = -6.5 ± 0.7 days
and ΔtCD = -14.3 ± 0.8 days. We spacially
deconvolved HST NICMOS2 F160W images to derive accurate astrometry of
the quasar images and to infer the light profile of the lensing galaxy.
We combined these images with a stellar population fitting of a deep VLT
spectrum of the lensing galaxy to estimate the baryonic fraction,
fb, in the Einstein radius. We measured fb =
0.65-0.10+0.13 if the lensing galaxy has a
Salpeter IMF and fb = 0.45-0.07+0.04 if
it has a Kroupa IMF. The spectrum also allowed us to estimate the
velocity dispersion of the lensing galaxy, σap = 222
± 34 km s-1. We used fb and
σap to constrain an analytical model of the lensing
galaxy composed of an Hernquist plus generalized NFW profile. We solved
the Jeans equations numerically for the model and explored the parameter
space under the additional requirement that the model must predict the
correct astrometry for the quasar images. Given the current error bars
on fb and σap, we did not constrain
H0 yet with high accuracy, i.e., we found a broad range of
models with χ2 < 1. However, narrowing this range is
possible, provided a better velocity dispersion measurement becomes
available. In addition, increasing the depth of the current HST imaging
data of HE 0435-1223 will allow us to combine ourconstraints with lens
reconstruction techniques that make use of the full Einstein ring that
is visible in this object.
Based on observations made with the 1.2 m Euler Swiss Telescope, the 1.5
m telescope of Maidanak Observatory in Uzbekistan, and with the 1.2 m
Mercator Telescope, operated on the island of La Palma by the Flemish
Community, at the Spanish Observatorio del Roque de los Muchachos of the
Instituto de Astrofísica de Canarias. The NASA/ESA Hubble Space
Telescope data was obtained from the data archive at the Space Telescope
Science Institute, which is operated by AURA, the Association of
Universities for Research in Astronomy, Inc., under NASA contract
NAS-5-26555.Light curves are only available at the CDS via anonymous ftp
to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/536/A53
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