We report a discovery of 6 massive galaxies with both extremely large Lya equivalent width and evolved stellar population at z ~ 3. These MAssive Extremely STrong Lya emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lya emitters (LAEs) with twelve optical intermediate-band data taken with Subaru/Suprime-Cam in the COSMOS field. Based on the SED fitting analysis for these LAEs, it is found that these MAESTLOs have (1) large rest-frame equivalent width of EW_0(Lya) ~ 100--300 A, (2) M_star ~ 10^10.5--10^11.1 M_sun, and (3) relatively low specific star formation rates of SFR/M_star ~ 0.03--1 Gyr^-1. Three of the 6 MAESTLOs have extended Lyα emission with a radius of several kpc 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 AGNs, the observed extended Lya emission is likely to be caused by 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.
@article{arxiv.1507.04439,
title = {Discovery of Massive, Mostly Star-formation Quenched Galaxies with Extremely Large Lyman-alpha Equivalent Widths at z ~ 3},
author = {Yoshiaki Taniguchi and Masaru Kajisawa and Masakazu A. R. Kobayashi and Tohru Nagao and Yasuhiro Shioya and Nick Z. Scoville and David B. Sanders and Peter L. Capak and Anton M. Koekemoer and Sune Toft and Henry J. McCracken and Olivier Le Fevre and Lidia Tasca and Kartik Sheth and Alvio Renzini and Simon Lilly and Marcella Carollo and Katarina Kovac and Olivier Ilbert and Eva Schinnerer and Hai Fu and Laurence Tresse and Richard E. Griffiths and Francesca Civano},
journal= {arXiv preprint arXiv:1507.04439},
year = {2015}
}
Comments
Accepted for publication in ApJ Letters on 15th July, 2015. 6 pages including 3 figures and 2 tables