Luminous and high stellar mass candidate galaxies at z ≈ 8 discovered in the cosmic assembly near-infrared deep extragalactic legacy survey

Haojing Yan*, Steven L. Finkelstein, Kuang Han Huang, Russell E. Ryan, Henry C. Ferguson, Anton M. Koekemoer, Norman A. Grogin, Mark Dickinson, Jeffrey A. Newman, Rachel S. Somerville, Romeel Davé, S. M. Faber, Casey Papovich, Yicheng Guo, Mauro Giavalisco, Kyoung Soo Lee, Naveen Reddy, Asantha R. Cooray, Brian D. Siana, Nimish P. HathiGiovanni G. Fazio, Matthew Ashby, Benjamin J. Weiner, Ray A. Lucas, Avishai Dekel, Laura Pentericci, Christopher J. Conselice, Dale D. Kocevski, Kamson Lai

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

Abstract / Description of output

One key goal of the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey is to track galaxy evolution back to z ≈ 8. Its two-tiered "wide and deep" strategy bridges significant gaps in existing near-infrared surveys. Here we report on z ≈ 8 galaxy candidates selected as F105W-band dropouts in one of its deep fields, which covers 50.1 arcmin2 to 4 ks depth in each of three near-infrared bands in the Great Observatories Origins Deep Survey southern field. Two of our candidates have J < 26.2 mag, and are >1 mag brighter than any previously known F105W-dropouts. We derive constraints on the bright end of the rest-frame ultraviolet luminosity function of galaxies at z ≈ 8, and show that the number density of such very bright objects is higher than expected from the previous Schechter luminosity function estimates at this redshift. Another two candidates are securely detected in Spitzer Infrared Array Camera images, which are the first such individual detections at z ≈ 8. Their derived stellar masses are on the order of a few × 109 M, from which we obtain the first measurement of the high-mass end of the galaxy stellar mass function at z ≈ 8. The high number density of very luminous and very massive galaxies at z ≈ 8, if real, could imply a large stellar-to-halo mass ratio and an efficient conversion of baryons to stars at such an early time.

Original languageEnglish
Article number177
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 10 Dec 2012

Keywords / Materials (for Non-textual outputs)

  • cosmology: observations
  • galaxies: luminosity function, mass function


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