John Moustakas

The First Galaxies

Massive galaxy clusters act as natural telescopes: their gravity magnifies the light of galaxies far behind them. Using Hubble Space Telescope observations of lensing clusters, I have searched for some of the most distant galaxies known, which formed within the first few hundred million years after the Big Bang.

Highlights

Color Hubble image of the galaxy cluster MACSJ0647.7+7015, with curves marking where lensing magnification is highest and labels JD1, JD2, and JD3 on the three lensed images of a distant galaxy.
The galaxy cluster MACSJ0647.7+7015 imaged by Hubble, with the three lensed images of MACS0647-JD labeled JD1–JD3 and the critical curves of the lens model. From Coe et al. 2013, ApJ, 762, 32; image NASA/ESA/CLASH.

A galaxy seen 400 million years after the Big Bang

In Hubble imaging from the CLASH survey, we found three magnified images of MACS0647-JD, a galaxy at z≈11 lensed by a massive foreground cluster. When it was announced, MACS0647-JD was the most distant galaxy candidate known.

Selected Papers

  1. A Census of Star-forming Galaxies in the z∼9–10 Universe based on HST+Spitzer Observations over 19 Clash Clusters: Three Candidate z∼9–10 Galaxies and Improved Constraints on the Star Formation Rate Density at z∼9.2
    R. Bouwens, L. Bradley, (J. Moustakas, 21st coauthor) et al. 2014, ApJ, 795, 126 ADS arXiv DOI
  2. Young Galaxy Candidates in the Hubble Frontier Fields. I. A2744
    W. Zheng, X. Shu, J. Moustakas et al. 2014, ApJ, 795, 93 ADS arXiv DOI
  3. CLASH: Three Strongly Lensed Images of a Candidate z ≈ 11 Galaxy
    D. Coe, A. Zitrin, (J. Moustakas, 15th coauthor) et al. 2013, ApJ, 762, 32 ADS arXiv DOI
  4. CLASH: Discovery of a Bright z∼6.2 Dwarf Galaxy Quadruply Lensed by MACS J0329.6-0211
    A. Zitrin, J. Moustakas, L. Bradley et al. 2012, ApJL, 747, 9 ADS arXiv DOI