A Lensing Study of IDCS J1426.5+3508: A Massive Galaxy Cluster at z=1.75
Abstract
We propose ACS/WFC and WFC3/IR imaging of IDCS J1426.5+3508, which at z=1.75 is the most massive cluster yet discovered at z>1.4, and the first cluster at this epoch for which the Sunyaev-Zel'dovich effect has been observed. Our previous work also revealed a giant arc associated with this cluster, making it the most distant known strong lensing cluster. The existence of this arc revives the longstanding arc statistics problem -- theoretical calculations predict that no such arc should exist across the entire sky. The aim of this program is to constrain the total mass and concentration of the dark matter halo to understand the origin of this discrepacy. A weak lensing determination of the total mass will also provide the first direct calibration of the SZ-lensing mass relation at this epoch. This calibration is of central relevance to programs aiming to use cluster counts out to this redshift to constrain dark energy, such as eROSITA and ground-based SZ searches. Moreover, our observations are designed to also enable detection of multiply imaged sources to enable joint strong+weak lensing analysis to better constrain the mass model. This cluster is extreme in mass for the redshift, anomalous as a strong lensing system, and unique among all clusters currently known.
- Publication:
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HST Proposal
- Pub Date:
- October 2012
- Bibcode:
- 2012hst..prop12994G