Galaxy Merger Fractions in Two Clusters at Z ∼ 2 Using the Hubble Space Telescope

Courtney Watson, Kim Vy Tran, Adam Tomczak, Leo Alcorn, Irene V. Salazar, Anshu Gupta, Ivelina Momcheva, Casey Papovich, Pieter Van Dokkum, Gabriel Brammer, Jennifer Lotz, Christopher N.A. Willmer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We measure the fraction of galaxy-galaxy mergers in two clusters at z ,F∼ ,F2 using imaging and grism observations from the Hubble Space Telescope. The two galaxy cluster candidates were originally identified as overdensities of objects using deep mid-infrared imaging and observations from the Spitzer Space Telescope, and were subsequently followed up with HST/WFC3 imaging and grism observations. We identify galaxy-galaxy merger candidates using high-resolution imaging with the WFC3 in the F105W, F125W, and F160W bands. Coarse redshifts for the same objects are obtained with grism observations in G102 for the z ,F∼ ,F1.6 cluster (IRC0222A) and G141 for the z ,F∼ ,F2 cluster (IRC0222B). Using visual classifications as well as a variety of selection techniques, we measure merger fractions of in IRC0222A and in IRC0222B. In comparison, we measure a merger fraction of for field galaxies at z ,F∼ ,F2. Our study indicates that the galaxy-galaxy merger fraction in clusters at z ,F∼ ,F2 is enhanced compared to the field population, but note that more cluster measurements at this epoch are needed to confirm our findings.

Original languageEnglish (US)
Article number63
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 20 2019


  • galaxies: clusters: general
  • galaxies: high-redshift
  • galaxies: interactions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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