HST Discovery of a z = 3.9 Multiply Imaged Galaxy Behind the Complex Cluster Lens WARPS J1415.1+36 at z = 1.026

TL;DR

This paper reports the discovery of a strongly lensed galaxy at z=3.9 behind a galaxy cluster at z=1.026, combining HST imaging and spectroscopic data to analyze the lensing system and cluster mass.

Contribution

It presents the first detailed analysis of a multiply imaged galaxy behind WARPS J1415.1+3612, integrating lensing, spectroscopic, and dynamical data for mass estimation.

Findings

Confirmed strong Lya emission at z=3.90 in the lensed galaxy.

Measured cluster velocity dispersion of 807+/-185 km/s.

Estimated cluster mass consistent with X-ray and weak lensing results.

Abstract

We report the discovery of a multiply lensed Ly Alpha (Lya) emitter at z = 3.90 behind the massive galaxy cluster WARPS J1415.1+3612 at z = 1.026. Images taken by the Hubble Space Telescope(HST) using ACS reveal a complex lensing system that produces a prominent, highly magnified arc and a triplet of smaller arcs grouped tightly around a spectroscopically confirmed cluster member. Spectroscopic observations using FOCAS on Subaru confirm strong Lya emission in the source galaxy and provide redshifts for more than 21 cluster members, from which we obtain a velocity dispersion of 807+/-185 km/s. Assuming a singular isothermal sphere profile, the mass within the Einstein ring (7.13+/-0.38") corresponds to a central velocity dispersion of 686+15-19 km/s for the cluster, consistent with the value estimated from cluster member redshifts. Our mass profile estimate from combining strong lensing and dynamical analyses is in good agreement with both X-ray and weak lensing results.