The ages and masses of Lyα galaxies at z ∼ 4.5

被引:104
作者
Finkelstein, Steven L. [1 ]
Rhoads, James E.
Malhotra, Sangeeta
Pirzkal, Norbert
Wang, Junxian
机构
[1] Arizona State Univ, Dept Phys, Tempe, AZ 85287 USA
[2] Arizona State Univ, Sch Earth & Space Explorat, Tempe, AZ 85287 USA
[3] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[4] Univ Sci & Technol China, Hefei 230026, Anhui, Peoples R China
关键词
galaxies : evolution; galaxies : fundamental parameters; galaxies : high-redshift; galaxies : ISM;
D O I
10.1086/513462
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We examine the stellar populations of a sample of 98 z similar to 4.5Ly alpha-emitting galaxies using their broadband colors derived from deep photometry at the Multiple Mirror Telescope (MMT). These galaxies were selected by narrowband excess from the Large Area Lyman Alpha survey. Twenty-two galaxies are detected in two or more of our MMT filters ( g', r', i', and z'), with calculated rest- frame equivalent widths (EWs) from 5 to 800 A. By comparing broad-and narrowband colors of these galaxies to synthetic colors from stellar population models, we determine their ages and stellar masses. The highest EW objects have an average age of 4 Myr, consistent with ongoing star formation. The lowest EW objects show an age of 40-200 Myr, consistent with the expectation that larger numbers of older stars are causing low EWs. We found masses ranging from 2x10(7) M-circle dot for the youngest objects in the sample to 2x10(9) M-circle dot for the oldest. It is possible that dust effects could produce large EWs even in older populations by allowing the Ly alpha photons to escape, even while the continuum is extinguished, and we present models for this scenario also.
引用
收藏
页码:1023 / 1029
页数:7
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