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The existence of strong lensing systems with Einstein radii (Re) 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 Re 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 Re in the range 3- 8, i.e. systems produced by galaxy group scale dark matter haloes, spanning a redshift range from 0.3 to 0.8. This opens a new window of exploration in the mass spectrum, around 10^{13}- 10^{14} M_{sun}, which is a crucial range for understanding the transition between galaxies and galaxy clusters. Our analysis is based on multi-colour CFHTLS images complemented with HST imaging and ground based spectroscopy. Large scale properties are derived from both the light distribution of the 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, the strong lenses coincide with the peak of the light distribution, suggesting that mass is traced by light. Most of the luminosity maps have complicated shapes, indicating that these intermediate mass structures are dynamically young. Fitting the reduced shear with a Singular Isothermal Sphere, we find sigma ~ 500 km/s and an upper limit of ~900 km/s for the whole sample. The mass to light ratio for the sample is found to be M/L_i ~ 250 (solar units, corrected for evolution), with an upper limit of 500. This can be compared to mass to light ratios of small groups (with sigma ~ 300 km/s and galaxy clusters with sigma > 1000 km/s, thus bridging the gap between these mass scales.
We analyzed the Einstein radius, $theta_E$, in our sample of SL2S galaxy groups, and compared it with $R_A$ (the distance from the arcs to the center of the lens), using three different approaches: 1.- the velocity dispersion obtained from weak lensi
The cold dark matter scenario predicts that a large number of dark subhalos should be located within the halo of each Milky-way sized galaxy. One tell-tale signature of such dark subhalos could be additional milliarcsecond-scale image splitting of qu
Galaxy group masses are important to relate these systems with the dark matter halo hosts. However, deriving accurate mass estimates is particularly challenging for low-mass galaxy groups. Moreover, calibration of bservational mass-proxies using weak
We use galaxy-galaxy lensing to study the dark matter halos surrounding a sample of Locally Brightest Galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central ga
I report discovery of a new galaxy-scale gravitational lens system, identified using public data from the MaNGA survey, as part of a systematic search for lensed background line-emitters. The lens is SDSS J170124.01+372258.0, a giant elliptical galax