Abell2537

From Cerny et al:

We detect four lensed systems in the field of Abell 2537, as described below (see also Table 5).

System #1 is lensed into four images. We identify three separate emission knots in this galaxy, designated as 1.1-1.4, 11.1-11.4, 12.1-12.4 in Figure 1.

System #2 is lensed into four multiple images, each one containing two emission knots. The images are labeled 2.1-2.4, 20.1-20.4 in Figure 1. We measure a spectro- scopic redshift of zspec = 3.611 for image 2.4, based on Lyα emission in our LDSS3 spectroscopy (Section 3.4). This falls within the 95% CL range of the photometric redshifts of the image and is slightly lower than its high- est probability peak (Table 5). We used the spectroscopic redshift as a fixed constraint in our lensing analysis.

System #3 has three multiple images. We identify three distinct emission knots in each image, labeled 3.1- 3.3, 30.1-30.3, 31.1-31.3 in Figure 1. We find that not fixing a second redshift parameter in this cluster (in ad- dition to the one spectroscopic redshift) causes the model to default to a non-physical result. We therefore fix the redshift of images 3.1-3.3 to the photometric redshift for this source, z = 3.2, in order to better constrain the lens- ing potential in the regions further away from the center of the cluster.

System #4 is a faint galaxy, labeled 4.1-4.2 in Fig- ure 1. The lensing analysis predicts additional images at two other locations within the field, but their predicted magnitudes are too faint to be detected, which explains their absence from the data.

The lens model for this cluster favors a combination of two cluster-scale halos, both located close to the center of the cluster within the strong lensing regime. As de- scribed above, we include perturbation from galaxy scale halos. We allow the parameters of the cluster-scale halos to be solved for by the lens model. Galaxy-scale halos are centered on cluster member galaxies and follow the scaling relations outlined in the introduction to Section 4. Table 5 lists the locations of the lensed galaxies and their redshifts. Table 6 lists the best-fit parameters of the resulting model.

Snapshots of all arc candidates.

Lens model below with two halos, modeled with epoch 2 data. The redshift of arc system 2 is fixed at 3.611 in accordance with spectroscopic observations.