2 research outputs found
Strong Lensing Model of SPT-CLJ0356-5337, a Major Merger Candidate at Redshift 1.0359
We present an analysis of the mass distribution inferred from strong lensing
by SPT-CL J0356-5337, a cluster of galaxies at redshift z = 1.0359 revealed in
the follow-up of the SPT-SZ clusters. The cluster has an Einstein radius of
Erad=14 for a source at z = 3 and a mass within 500 kpc of M_500kpc =
4.0+-0.8x10^14Msol. Our spectroscopic identification of three multiply-imaged
systems (z = 2.363, z = 2.364, and z = 3.048), combined with HST F606W-band
imaging allows us to build a strong lensing model for this cluster with an rms
of <0.3'' between the predicted and measured positions of the multiple images.
Our modeling reveals a two-component mass distribution in the cluster. One mass
component is dominated by the brightest cluster galaxy and the other component,
separated by ~170 kpc, contains a group of eight red elliptical galaxies
confined in a ~9'' (~70 kpc) diameter circle. We estimate the mass ratio
between the two components to be between 1:1.25 and 1:1.58. In addition,
spectroscopic data reveal that these two near-equal mass cores have only a
small velocity difference of 300 km/s between the two components. This small
radial velocity difference suggests that most of the relative velocity takes
place in the plane of the sky, and implies that SPT-CL J0356-5337 is a major
merger with a small impact parameter seen face-on. We also assess the relative
contributions of galaxy-scale halos to the overall mass of the core of the
cluster and find that within 800 kpc from the brightest cluster galaxy about
27% of the total mass can be attributed to visible and dark matter associated
with galaxies, whereas only 73% of the total mass in the core comes from
cluster-scale dark matter halos.Comment: 19 pages, 11 figures. Submitted to Ap
COOL-LAMPS. IV. A Sample of Bright Strongly Lensed Galaxies at 3 < z < 4
We report the discovery of five bright, strong gravitationally lensed galaxies at 3 < z < 4: COOL J0101+2055 (z = 3.459), COOL J0104−0757 (z = 3.480), COOL J0145+1018 (z = 3.310), COOL J0516−2208 (z = 3.549), and COOL J1356+0339 (z = 3.753). These galaxies have magnitudes of rAB, zAB < 21.81 mag and are lensed by galaxy clusters at 0.26 < z < 1. This sample nearly doubles the number of known bright lensed galaxies with extended arcs at 3 < z < 4. We characterize the lensed galaxies using ground-based grz/giy imaging and optical spectroscopy. We report model-based magnitudes and derive stellar masses, dust content, and star formation rates via stellar population synthesis modeling. Building lens models based on ground-based imaging, we estimate source magnifications ranging from ∼29 to ∼180. Combining these analyses, we derive demagnified stellar masses in the range and star formation rates in the youngest age bin in the range , placing the sample galaxies on the massive end of the star-forming main sequence in this redshift interval. In addition, three of the five galaxies have strong Lyα emissions, offering unique opportunities to study Lyα emitters at high redshift in future work