Discovery of massive, mostly star formation quenched galaxies with extremely large ly alpha equivalent widths at z similar to 3

Yoshiaki Taniguchi , Masaru Kajisawa , Masakazu A. R. Kobayashi , Tohru Nagao , Yasuhiro Shioya , Nick Z. Scoville , David B. Sanders , Peter L. Capak , Anton M. Koekemoer , Sune Toft , Henry J. Mccracken (1) , Olivier Le Fèvre (2) , Lidia Tasca (2) , Kartik Sheth (3, 4) , Alvio Renzini , Simon Lilly , Marcella Carollo (5) , Katarina Kovac , Olivier Ilbert (2) , Eva Schinnerer (6) , Hai Fu (7) , Laurence Tresse (2) , Richard E. Griffiths , Francesca Civano

1 IAP - Institut d'Astrophysique de Paris
2 LAM - Laboratoire d'Astrophysique de Marseille
3 Spitzer Science Center, California Institute of Technology, Pasadena
4 CALTECH - California Institute of Technology
5 Department of Physics and Astronomy [UCLA Los Angeles]
6 MPIA - Max-Planck-Institut für Astronomie
7 Department of Physics and Astronomy [Iowa City]

We report a discovery of six massive galaxies with both extremely large Ly alpha equivalent widths (EWs) and evolved stellar populations at z similar to 3. These MAssive Extremely STrong Ly alpha emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Ly alpha emitters (LAEs) with 12 optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the spectral energy distribution fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame EWs of EW0 (Ly alpha) similar to 100-300 angstrom, (2) M-star similar to 10(10.5) -10(11.1) M-circle dot, and (3) relatively low specific star formation rates of SFR/M-star similar to 0.03-1 Gyr(-1). Three of the six MAESTLOs have extended Ly alpha emission with a radius of several kiloparsecs, although they show very compact morphology in the HST/ACS images, which correspond to the rest-frame UV continuum. Since the MAESTLOs do not show any evidence for active galactic nuclei, the observed extended Ly alpha emission is likely to be caused by a star formation process including the superwind activity. We suggest that this new class of LAEs, MAESTLOs, provides a missing link from star-forming to passively evolving galaxies at the peak era of the cosmic star formation history.

Mots clés: Cosmology: observations; Early universe; Galaxies: evolution; Galaxies: formation; Galaxies: high-redshift

Domaines: Astrophysique [astro-ph]

Yoshiaki Taniguchi, Masaru Kajisawa, Masakazu A. R. Kobayashi, Tohru Nagao, Yasuhiro Shioya, et al.. Discovery of massive, mostly star formation quenched galaxies with extremely large ly alpha equivalent widths at z similar to 3. The Astrophysical journal letters, 2015, 809 (1), ⟨10.1088/2041-8205/809/1/L7⟩. ⟨hal-01439952⟩