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Published August 10, 2015 | Published + Submitted
Journal Article Open

Discovery of Massive, Mostly Star Formation Quenched Galaxies with Extremely Large Lyα Equivalent Widths at z ~ 3


We report a discovery of six massive galaxies with both extremely large Lyα equivalent widths (EWs) and evolved stellar populations at z ~ 3. These MAssive Extremely STrong Lyα emitting Objects (MAESTLOs) have been discovered in our large-volume systematic survey for strong Lyα 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 EW_0 (Lyα) ~ 100–300 Å, (2) M_★ ~ 10^(10.5)–10^(11.1) M_⊙, and (3) relatively low specific star formation rates of SFR/M_★ ~ 0.03–1 Gyr^(−1). Three of the six MAESTLOs have extended Lyα 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 Lyα 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.

Additional Information

© 2015 American Astronomical Society. Received 2015 May 25; accepted 2015 July 14; published 2015 August 5. We would like to thank both the Subaru and HST staff for their invaluable help, as well as all members of the COSMOS team. We would also like to thank the anonymous referee for valuable suggestions and comments. We also thank Alex Hagen for kindly providing us with the information of their LAEs. This work was financially supported in part by JSPS (Y. T.: 15340059, 17253001, 19340046, and 23244031; T.N.: 23654068 and 25707010). Data analysis was in part carried out on the common use data analysis computer system at the Astronomy Data Center, ADC, of the National Astronomical Observatory of Japan.

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Submitted - 1507.04439v1.pdf

Published - 2041-8205_809_1_L7.pdf


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August 22, 2023
August 22, 2023