2006/05/31 by Masataka Ando, Kouji Ohta, Ikuru Iwata +3 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Emission spectrum #Equivalent width #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminosity function #Physics #Spectral line #astro-ph
paper · pdf · doi:10.1086/505652
published as Astrophys.J. 645 (2006) L9-L12 · 12 pages, 1 figure, ApJ(letters) in press: revised to correct references and some typographical errors
openalex publication_date 2006/06/15 · arxiv created 2006/06/28 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report a deficiency of luminous Lyman break galaxies (LBGs) with a large rest-frame equivalent width (EW rest ) of Lyα emission at z ~ 5-6. Combining our spectroscopic sample of LBGs at z ~ 5 and those from the literature, we found that luminous LBGs at z ~ 5-6 generally show weak Lyα emissions, while faint LBGs show a wide range of Lyα EW rest and tend to have strong (EW rest ≳ 20 Å) Lyα emissions; i.e., there is a deficiency of strong Lyα emission in luminous LBGs. There seems to be a threshold UV luminosity for the deficiency; it is M 1400 = -21.5 to -21.0 mag, which is close to or somewhat brighter than the M * of the UV luminosity function at z ~ 5 and 6. Since the large EW rest of Lyα emission can be seen among the faint LBGs, the ratio of Lyα emitters to LBGs may change rather abruptly with the UV luminosity. If the weakness of Lyα emission is due to dust absorption, the deficiency suggests that luminous LBGs at z = 5-6 tend to be in dusty and more chemically evolved environments and that they begin star formation earlier than faint LBGs, although other causes cannot be ruled out.