2009A&A...502..445L


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.05CET19:53:55

2009A&A...502..445L - Astronomy and Astrophysics, volume 502, 445-456 (2009/8-1)

A new window of exploration in the mass spectrum: strong lensing by galaxy groups in the SL2S.

LIMOUSIN M., CABANAC R., GAVAZZI R., KNEIB J.-P., MOTTA V., RICHARD J., THANJAVUR K., FOEX G., PELLO R., CRAMPTON D., FAURE C., FORT B., JULLO E., MARSHALL P., MELLIER Y., MORE A., SOUCAIL G., SUYU S., SWINBANK M., SYGNET J.-F., TU H., VALLS-GABAUD D., VERDUGO T. and WILLIS J.

Abstract (from CDS):

The existence of strong lensing systems with Einstein radii covering the full mass spectrum, from ∼1-2" (produced by galaxy scale dark matter haloes) to >10" (produced by galaxy cluster scale haloes) have long been predicted. Many lenses with Einstein radii around 1-2" and above 10" have been reported but very few in between. In this article, we present a sample of 13 strong lensing systems with Einstein radii in the range 3"-8" (or image separations in the range 6"-16"), i.e. systems produced by galaxy group scale dark matter haloes. This group sample spans a redshift range from 0.3 to 0.8. This opens a new window of exploration in the mass spectrum, around 1013-1014M, a crucial range for understanding the transition between galaxies and galaxy clusters, and a range that have not been extensively probed with lensing techniques. These systems constitute a subsample of the Strong Lensing Legacy Survey (SL2S), which aims to discover strong lensing systems in the Canada France Hawaii Telescope Legacy Survey (CFHTLS). The sample is based on a search over 100 square degrees, implying a number density of ∼0.13 groups per square degree. Our analysis is based on multi-colour CFHTLS images complemented with Hubble Space Telescope imaging and ground based spectroscopy. Large scale properties are derived from both the light distribution of elliptical galaxies group members and weak lensing of the faint background galaxy population. On small scales, the strong lensing analysis yields Einstein radii between 2.5" and 8". On larger scales, strong lens centres coincide with peaks of light distribution, suggesting that light traces mass. Most of the luminosity maps have complicated shapes, implying that these intermediate mass structures may be dynamically young. A weak lensing signal is detected for 6 groups and upper limits are provided for 6 others. Fitting the reduced shear with a Singular Isothermal Sphere, we find σSIS∼500km/s with large error bars and an upper limit of ∼900km/s for the whole sample (except for the highest redshift structure whose velocity dispersion is consistent with that of a galaxy cluster). The mass-to-light ratio for the sample is found to be M/Li∼250 (solar units, corrected for evolution), with an upper limit of 500. This compares with mass-to-light ratios of small groups (with σSIS∼300km/s) and galaxy clusters (with σSIS>1000km/s), thus bridging the gap between these mass scales. The group sample released in this paper will be complemented with other observations, providing a unique sample to study this important intermediate mass range in further detail.

Abstract Copyright:

Journal keyword(s): gravitational lensing: cosmology: large-scale structure of Universe

Nomenclature: Table 3: [LCG2009] SL2S Group JHHMMS+DDMM N=13.

Simbad objects: 16

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Number of rows : 16

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 [LCG2009] SL2S Group J02140-0532 GrG 02 14 08.0316 -05 35 32.621           ~ 7 0
2 [LCG2009] SL2S Group J02215-0647 GrG 02 21 51.183 -06 47 32.79           ~ 4 0
3 [LCG2009] SL2S Group J02254-0737 GrG 02 25 46.1184 -07 37 38.468           ~ 3 0
4 [LCG2009] SL2S Group J08544-0121 GrG 08 54 46.5480 -01 21 37.262           ~ 8 0
5 [LCG2009] SL2S Group J08591-0345 GrG 08 59 14.4576 -03 45 14.478           ~ 3 0
6 [LCG2009] SL2S Group J09013-0158 GrG 09 01 39.4632 -01 58 52.200           ~ 2 0
7 [LCG2009] SL2S Group J09413-1100 GrG 09 41 34.747 -11 00 54.33           ~ 5 0
8 NAME Cosmic Horseshoe G 11 48 33.10 +19 30 03.2           ~ 67 0
9 [LCG2009] SL2S Group J14081+5429 GrG 14 08 13.939 +54 29 04.68           ~ 5 0
10 [LCG2009] SL2S Group J14300+5546 GrG 14 30 00.660 +55 46 47.87           ~ 7 0
11 [LCG2009] SL2S Group J14314+5533 GrG 14 31 39.744 +55 33 22.71           ~ 6 0
12 GB6 B2108+2118 gLS 21 10 53.30 +21 31 09.0           ~ 26 0
13 [LCG2009] SL2S Group J22130-0030 GrG 22 13 06.91920 -00 30 37.0953           ~ 2 0
14 [LCG2009] SL2S Group J22133+0048 GrG 22 13 31.85760 +00 48 36.0977           ~ 3 0
15 3XMM J222144.0-005306 GrG 22 21 43.74240 -00 53 02.5549           ~ 6 0
16 NAME Local Group GrG ~ ~           ~ 7188 0

    Equat.    Gal    SGal    Ecl

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2021.03.05-19:53:55

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