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We present six strongly gravitationally lensed Ly α emitters (LAEs) at z ∼ 4–5 with Hubble Space Telescope (HST) narrowband imaging isolating Ly α . Through complex radiative transfer Ly α encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Ly α morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Ly α spatial resolution. In this work we take advantage of high-resolution Ly α imaging boosted by lensing magnification, allowing us to probe subgalactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in spectral energy distribution fitting, providing estimates of the stellar masses (∼10 ^8 –10 ^9 M _⊙ ), stellar population ages ( t _50 < 40 Myr), and amounts of dust ( A _V ∼ 0.1–0.6, statistically consistent with zero). We employ nonparametric star formation histories to probe the young stellar populations which create the Ly α . We also examine the offsets between the Ly α and stellar continuum, finding small upper limits of offsets (

We present an extensive spectroscopic follow-up campaign of 29 strong lensing (SL) selected galaxy clusters discovered primarily in the Second Red-Sequence Cluster Survey (RCS-2). Our spectroscopic analysis yields redshifts for 52 gravitational arcs present in the core of our galaxy clusters, which correspond to 35 distinct background sources that are clearly distorted by the gravitational potential of these clusters. These lensed galaxies span a wide redshift range of 0.8 ≤ z ≤ 2.9, with a median redshift of zs = 1.8 ± 0.1. We also measure reliable redshifts for 1004 cluster members, allowing us to obtain robust velocity dispersion measurements for 23 of these clusters, which we then use to determine their dynamical masses by using a simulation-based σDM − M200 scaling relation. The redshift and mass ranges covered by our SL sample are 0.22 ≤ z ≤ 1.01 and , respectively. We analyze and quantify some possible effects that might bias our mass estimates, such as the presence of substructure, the region where cluster members are selected for spectroscopic follow-up, the final number of confirmed members, and line-of-sight effects. We find that 10 clusters of our sample with Nmem ≳ 20 show signs of dynamical substructure. However, the velocity data of only one system is inconsistent with a uni-modal distribution. We therefore assume that the substructures are only marginal and not of comparable size to the clusters themselves. Consequently, our velocity dispersion and mass estimates can be used as priors for SL mass reconstruction studies and also represent an important step toward a better understanding of the properties of the SL galaxy cluster population. [ABSTRACT FROM AUTHOR]

We present a multi-wavelength photometric and spectroscopic study of 42 Brightest Cluster Galaxies (BCGs) in two samples of galaxy clusters chosen for a gravitational lensing study. The study’s initial sample combines 25 BCGs from the Cluster Lensing and Supernova Survey with Hubble sample and 37 BCGs from the Sloan Giant Arcs Survey with a total redshift range of Using archival GALEX, HubbleSpace Telescope, Wide-Field Infrared Survey Explorer, Herschel, and Very Large Array data we determine the BCGs’ stellar mass, radio power, and star formation rates. The radio power is higher than expected if due to star formation, consistent with the BCGs being active galactic nucleus (AGN)-powered radio sources. This suggests that the AGN and star formation are both fueled by cold gas in the host galaxy. The specific star formation rate (sSFR) is low and constant with redshift. The mean sSFR is 9.42 × 10−12 yr−1, which corresponds to a mass doubling time of 105 billion years. These findings are consistent with models for hierarchical formation of BCGs, which suggest that star formation is no longer a significant channel for galaxy growth for z 1. Instead, stellar growth (of the order of a factor of at least two) during this period is expected to occur mainly via minor dry mergers. [ABSTRACT FROM AUTHOR]