133 research outputs found
On the accuracy of the Perturbative Approach for Strong Lensing: Local Distortion for Pseudo-Elliptical Models
The Perturbative Approach (PA) introduced by \citet{alard07} provides
analytic solutions for gravitational arcs by solving the lens equation
linearized around the Einstein ring solution. This is a powerful method for
lens inversion and simulations in that it can be used, in principle, for
generic lens models. In this paper we aim to quantify the domain of validity of
this method for three quantities derived from the linearized mapping: caustics,
critical curves, and the deformation cross section (i.e. the arc cross section
in the infinitesimal circular source approximation). We consider lens models
with elliptical potentials, in particular the Singular Isothermal Elliptic
Potential and Pseudo-Elliptical Navarro--Frenk--White models. We show that the
PA is exact for this first model. For the second, we obtain constraints on the
model parameter space (given by the potential ellipticity parameter
and characteristic convergence ) such that the PA is
accurate for the aforementioned quantities. In this process we obtain analytic
expressions for several lensing functions, which are valid for the PA in
general. The determination of this domain of validity could have significant
implications for the use of the PA, but it still needs to be probed with
extended sources.Comment: Accepted for publication in MNRA
First Galaxy-Galaxy Lensing Measurement of Satellite Halo Mass in the CFHT Stripe-82 Survey
We select satellite galaxies from the galaxy group catalog constructed with
the SDSS spectroscopic galaxies and measure the tangential shear around these
galaxies with source catalog extracted from CFHT/MegaCam Stripe-82 Survey to
constrain the mass of subhalos associated with them. The lensing signal is
measured around satellites in groups with masses in the range [10^{13},
5x10^{14}]h^{-1}M_{sun}, and is found to agree well with theoretical
expectation. Fitting the data with a truncated NFW profile, we obtain an
average subhalo mass of log M_{sub}= 11.68 \pm 0.67 for satellites whose
projected distances to central galaxies are in the range [0.1, 0.3] h^{-1}Mpc,
and log M_{sub}= 11.68 \pm 0.76 for satellites with projected halo-centric
distance in [0.3, 0.5] h^{-1}Mpc. The best-fit subhalo masses are comparable to
the truncated subhalo masses assigned to satellite galaxies using abundance
matching and about 5 to 10 times higher than the average stellar mass of the
lensing satellite galaxies.Comment: 7 pages, 4 figures, accepted by MNRA
The Mass-Concentration Relation and the Stellar-to-Halo Mass Ratio in the CFHT Stripe 82 Survey
We present a new measurement of the mass-concentration relation and the
stellar-to-halo mass ratio over the halo mass range to
. To achieve this, we use weak lensing measurements
from the CFHT Stripe 82 Survey (CS82), combined with the central galaxies from
the redMaPPer cluster catalogue and the LOWZ/CMASS galaxy sample of the Sloan
Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data
Release. The stacked lensing signals around these samples are modelled as a sum
of contributions from the central galaxy, its dark matter halo, and the
neighboring halos, as well as a term for possible centering errors. We measure
the mass-concentration relation: with
for and for . These amplitudes and slopes are completely
consistent with predictions from recent simulations. We also measure the
stellar-to-halo mass ratio for our samples, and find results consistent with
previous measurements from lensing and other techniques.Comment: 10 pages, 3 figures, 3 table
Measuring subhalo mass in redMaPPer clusters with CFHT Stripe 82 Survey
We use the shear catalog from the CFHT Stripe-82 Survey to measure the
subhalo masses of satellite galaxies in redMaPPer clusters. Assuming a Chabrier
Initial Mass Function (IMF) and a truncated NFW model for the subhalo mass
distribution, we find that the sub-halo mass to galaxy stellar mass ratio
increases as a function of projected halo-centric radius , from at to
at
. We also investigate the dependence of subhalo masses on stellar
mass by splitting satellite galaxies into two stellar mass bins:
and . The best-fit subhalo mass of the more massive satellite galaxy bin
is larger than that of the less massive satellites: () versus ().Comment: 10 pages, 8 figures, accepted by MNRA
Weak-lensing calibration of a stellar mass-based mass proxy for redMaPPer and Voronoi Tessellation clusters in SDSS Stripe 82
We present the first weak lensing calibration of , a new galaxy
cluster mass proxy corresponding to the total stellar mass of red and blue
members, in two cluster samples selected from the SDSS Stripe 82 data: 230
redMaPPer clusters at redshift and 136 Voronoi Tessellation
(VT) clusters at . We use the CS82 shear catalog and stack
the clusters in bins to measure a mass-observable power law
relation. For redMaPPer clusters we obtain , . For VT clusters, we find
, and , for a low and a high redshift bin, respectively. Our results are
consistent, internally and with the literature, indicating that our method can
be applied to any cluster finding algorithm. In particular, we recommend that
be used as the mass proxy for VT clusters. Catalogs including
measurements will enable its use in studies of galaxy evolution
in clusters and cluster cosmology.Comment: Updated to be consistent with the published versio
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