Paper 1: The JWST PEARLS View of the El Gordo Galaxy Cluster and of the Structure It Magnifies

Abstract

The massive galaxy cluster El Gordo (z=0.87) imprints multitudes of gravitationally lensed arcs onto James Webb Space Telescope (JWST) Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam imaging were obtained in the ``Prime Extragalactic Areas for Reionization and Lensing Science'' (``PEARLS'') program. PSF-matched photometry across Hubble Space Telescope (HST) and NIRCam filters supplies new photometric redshifts. A new light-traces-mass lens model based on 56 image multiplicities identifies the two mass peaks and yields a mass estimate within 500 kpc of ~(7.0 +/- 0.30) x 10^14 Msun. A search for substructure in the 140 cluster members with spectroscopic redshifts confirms the two main mass components. The southeastern mass peak that contains the BCG is more tightly bound than the northwestern one. The virial mass within 1.7 Mpc is (5.1 +/- 0.60) x 10^14 Msun, lower than the lensing mass. A significant transverse velocity component could mean the virial mass is underestimated. We contribute one new member to the previously known z=4.32 galaxy group. Intrinsic (delensed) positions of the five secure group members span a physical extent of ~60 kpc. Thirteen additional candidates selected by spectroscopic/photometric constraints are small and faint with a mean intrinsic luminosity ~2.2 mag fainter than L*. NIRCam imaging admits a fairly wide range of brightnesses and morphologies for the group members, suggesting a more diverse galaxy population in this galaxy overdensity.

24 pages, accepted by ApJ

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Cited by in corpus (8)

• Galaxy Mergers in the Epoch of Reionization I: A JWST Study of Pair Fractions, Merger Rates, and Stellar Mass Accretion Rates at $z=4.5-11.5$
• JWST's PEARLS: resolved study of the stellar and dust components in starburst galaxies at cosmic noon
• Lonely Little Red Dots: Challenges to the AGN-nature of little red dots through their clustering and spectral energy distributions
• Galaxy Mergers in the Epoch of Reionization II: Major Merger-Triggered Star Formation and AGN Activities at $z=$ 4.5-8.5
• El Gordo needs El Anzuelo: Probing the structure of cluster members with multi-band extended arcs in JWST data
• PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST
• Microlensing at Cosmological Distances: Event Rate Predictions in the Warhol Arc of MACS 0416
• PASSAGES: The Discovery of a Strongly Lensed Protocluster Core Candidate at Cosmic Noon