MOIRCS Deep Survey. VII. NIR morphologies of star-forming galaxies at redshift z ∼ 1

Masahiro Konishi, Masayuki Akiyama, Masaru Kajisawa, Takashi Ichikawa, Ryuji Suzuki, Chihiro Tokoku, Yuka Katsuno Uchimoto, Tomohiro Yoshikawa, Ichi Tanaka, Masato Onodera, Masami Ouchi, Koji Omata, Tetsuo Nishimura, Toru Yamada

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We investigated rest-frame near-infrared (NIR) morphologies of a sample of 139 galaxies with Ms ≥ 1 × 1010M at z = 0.8-1.2 in the GOODS-North field using our deep NIR imaging data (MOIRCS Deep Survey, MODS). We focused on Luminous Infrared Galaxies (LIRGs), which dominate a high star formation rate (SFR) density at z ∼ 1, in a sample identified by cross-correlating with the Spitzer/MIPS 24 μm source catalog. We performed twodimensional light profile fittings of z ∼ 1 galaxies in the Ks-band (rest-frame J -band) with a single-component Sérsic model. We found that at z ∼ 1, ∼ 90% of the LIRGs have low Sérsic indices (n < 2.5, similar to disk-like galaxies) in the Ks-band, and that those disk-like LIRGs consist of ∼ 60% of the whole disk-like sample above Ms ≥ 3 × 1010M⊙ The z ∼ 1 disk-like LIRGs are comparable to or ∼ 20% smaller at the maximum in size compared to local disk-like galaxies in the same stellar mass range. When we examined rest-frame UV-optical morphologies using the HST/ACS images, the rest-frame B-band sizes of the z ∼ 1 disk-like galaxies were found to be comparable to those of the local disk-like galaxies, as reported by previous studies on the size evolution of disklike galaxies in the rest-frame optical band. By measuring color gradients (galaxy sizes as a function of wavelength) of the z ∼ 1 and local disk-like galaxies, we found that the z ∼ 1 disk-like galaxies have a 3-5 times steeper color gradient than the local ones. Our results indicate that (i) more than a half of the relatively massive disk-like galaxies at z ∼ 1 are in violent star-formation epochs observed as LIRGs, and also (ii) that most of those LIRGs are constructing their fundamental disk structure vigorously. The high SFR density in the universe at z ∼ 1 may be dominated by such star formation in the disk region in massive galaxies.

Original languageEnglish
Pages (from-to)S363-S377
JournalPublications of the Astronomical Society of Japan
Volume63
Issue numberSPEC. ISSUE 2
DOIs
Publication statusPublished - 2011 Mar 25

Keywords

  • Galaxies: spiral
  • Galaxies: starburst
  • Galaxies: structure
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Konishi, M., Akiyama, M., Kajisawa, M., Ichikawa, T., Suzuki, R., Tokoku, C., Uchimoto, Y. K., Yoshikawa, T., Tanaka, I., Onodera, M., Ouchi, M., Omata, K., Nishimura, T., & Yamada, T. (2011). MOIRCS Deep Survey. VII. NIR morphologies of star-forming galaxies at redshift z ∼ 1. Publications of the Astronomical Society of Japan, 63(SPEC. ISSUE 2), S363-S377. https://doi.org/10.1093/pasj/63.sp2.S363