TY - JOUR
T1 - Inference of the cold dark matter substructure mass function at z = 0.2 using strong gravitational lenses
AU - Vegetti, S.
AU - Koopmans, L. V. E.
AU - Auger, M. W.
AU - Treu, T.
AU - Bolton, A. S.
PY - 2014/8
Y1 - 2014/8
N2 - We present the results of a search for galaxy substructures in a sample
of 11 gravitational lens galaxies from the Sloan Lens ACS Survey by
Bolton et al. We find no significant detection of mass clumps, except
for a luminous satellite in the system SDSS J0956+5110. We use these
non-detections, in combination with a previous detection in the system
SDSS J0946+1006, to derive constraints on the substructure mass function
in massive early-type host galaxies with an average redshift
˜ 0.2 and an average velocity dispersion
˜ 270 km s-1. We perform
a Bayesian inference on the substructure mass function, within a median
region of about 32 kpc2 around the Einstein radius
( ˜ 4.2 kpc). We infer a mean projected
substructure mass fraction f = 0.0076_{-0.0052}^{+0.0208} at the 68 per
cent confidence level and a substructure mass function slope α
<2.93 at the 95 per cent confidence level for a uniform prior
probability density on α. For a Gaussian prior based on cold dark
matter (CDM) simulations, we infer f = 0.0064^{+0.0080}_{-0.0042} and a
slope of α = 1.90^{+0.098}_{-0.098} at the 68 per cent confidence
level. Since only one substructure was detected in the full sample, we
have little information on the mass function slope, which is therefore
poorly constrained (i.e. the Bayes factor shows no positive preference
for any of the two models). The inferred fraction is consistent with the
expectations from CDM simulations and with inference from flux ratio
anomalies at the 68 per cent confidence level.
AB - We present the results of a search for galaxy substructures in a sample
of 11 gravitational lens galaxies from the Sloan Lens ACS Survey by
Bolton et al. We find no significant detection of mass clumps, except
for a luminous satellite in the system SDSS J0956+5110. We use these
non-detections, in combination with a previous detection in the system
SDSS J0946+1006, to derive constraints on the substructure mass function
in massive early-type host galaxies with an average redshift
˜ 0.2 and an average velocity dispersion
˜ 270 km s-1. We perform
a Bayesian inference on the substructure mass function, within a median
region of about 32 kpc2 around the Einstein radius
( ˜ 4.2 kpc). We infer a mean projected
substructure mass fraction f = 0.0076_{-0.0052}^{+0.0208} at the 68 per
cent confidence level and a substructure mass function slope α
<2.93 at the 95 per cent confidence level for a uniform prior
probability density on α. For a Gaussian prior based on cold dark
matter (CDM) simulations, we infer f = 0.0064^{+0.0080}_{-0.0042} and a
slope of α = 1.90^{+0.098}_{-0.098} at the 68 per cent confidence
level. Since only one substructure was detected in the full sample, we
have little information on the mass function slope, which is therefore
poorly constrained (i.e. the Bayes factor shows no positive preference
for any of the two models). The inferred fraction is consistent with the
expectations from CDM simulations and with inference from flux ratio
anomalies at the 68 per cent confidence level.
KW - g
UR - http://adsabs.harvard.edu/abs/2014MNRAS.442.2017V
U2 - 10.1093/mnras/stu943
DO - 10.1093/mnras/stu943
M3 - Article
SN - 1365-2966
VL - 442
SP - 2017
EP - 2035
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
ER -