Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV luminosity functions at z ∼ 4-7 derived with the half-million dropouts on the 100 deg2 sky

Yoshiaki Ono, Masami Ouchi, Yuichi Harikane, Jun Toshikawa, Michael Rauch, Suraphong Yuma, Marcin Sawicki, Takatoshi Shibuya, Kazuhiro Shimasaku, Masamune Oguri, Chris Willott, Mohammad Akhlaghi, Masayuki Akiyama, Jean Coupon, Nobunari Kashikawa, Yutaka Komiyama, Akira Konno, Lihwai Lin, Yoshiki Matsuoka, Satoshi MiyazakiTohru Nagao, Kimihiko Nakajima, John Silverman, Masayuki Tanaka, Yoshiaki Taniguchi, Shiang Yu Wang

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53 Citations (Scopus)

Abstract

We study the UV luminosity functions (LFs) at z ∼ 4, 5, 6, and 7 based on the deep largearea optical images taken by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP). On the 100 deg2 sky of the HSC SSP data available to date, we take enormous samples consisting of a total of 579565 dropout candidates at z ∼ 4-7 by the standard color selection technique, 358 out of which are spectroscopically confirmed by our followup spectroscopy and other studies. We obtain UV LFs at z ∼ 4-7 that span a very wide UV luminosity range of ∼0.002-100 L∗UV (-26 < MUV < -14 mag) by combining LFs from our program and the ultra-deep Hubble Space Telescope legacy surveys.We derive three parameters of the best-fit Schechter function, φ∗, M∗ UV, and α, of the UV LFs in the magnitude range where the active galactic nucleus (AGN) contribution is negligible, and find that α and φ∗ decrease from z ∼ 4 to 7 with no significant evolution of M∗UV. Because our HSC SSP data bridge the LFs of galaxies and AGNs with great statistical accuracy, we carefully investigate the bright end of the galaxy UV LFs that are estimated by the subtraction of the AGN contribution either aided by spectroscopy or the best-fit AGN UV LFs.We find that the bright end of the galaxy UV LFs cannot be explained by the Schechter function fits at>2 σ significance, and require either double power-law functions or modified Schechter functions that consider a magnification bias due to gravitational lensing.

Original languageEnglish
Article numberS10
JournalPublications of the Astronomical Society of Japan
Volume70
Issue numberSpecial Issue 1
DOIs
Publication statusPublished - 2018 Jan 1

Keywords

  • Evolution-galaxies
  • Formation-galaxies
  • Galaxies
  • High-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Ono, Y., Ouchi, M., Harikane, Y., Toshikawa, J., Rauch, M., Yuma, S., Sawicki, M., Shibuya, T., Shimasaku, K., Oguri, M., Willott, C., Akhlaghi, M., Akiyama, M., Coupon, J., Kashikawa, N., Komiyama, Y., Konno, A., Lin, L., Matsuoka, Y., ... Wang, S. Y. (2018). Great Optically Luminous Dropout Research Using Subaru HSC (GOLDRUSH). I. UV luminosity functions at z ∼ 4-7 derived with the half-million dropouts on the 100 deg2 sky. Publications of the Astronomical Society of Japan, 70(Special Issue 1), [S10]. https://doi.org/10.1093/pasj/psx103