The stellar mass, star formation rate and dark matter halo properties of LAEs at z ∼ 2

PASJ: Publications of the Astronomical Society of Japan

Silverman, John D¹  Kusakabe, Haruka²  Harikane, Yuichi²  Shimasaku, Kazuhiro²  Konno, Akira²  Hashimoto, Takuya³  Goto, Ryosuke⁴  Nakajima, Kimihiko⁵  Capak, Peter L⁶  Ouchi, Masami⁷ 

[1] College of General Education, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan;Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. München, Germany;Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan;Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583, Japan;National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Research Center for the Early Universe, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

关键词: galaxies: evolution;    galaxies: halos;    galaxies: high-redshift;    galaxies: star formation;   

DOI  :  10.1093/pasj/psx148

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We present average stellar population properties and dark matter halo masses of z ∼ 2 Lyα emitters (LAEs) from spectral energy distribution fitting and clustering analysis, respectively, using ≃ 1250 objects (⁠|$\mathit {NB387}\le 25.5$|⁠) in four separate fields of ≃ 1 deg2 in total. With an average stellar mass of 10.2 ± 1.8 × 108 M⊙ and star formation rate of 3.4 ± 0.4 M⊙ yr−1, the LAEs lie on an extrapolation of the star-formation main sequence (MS) to low stellar mass. Their effective dark matter halo mass is estimated to be |$4.0_{-2.9}^{+5.1} \times 10^{10}{\,\,}M_{\odot }$| with an effective bias of |$1.22^{+0.16}_{-0.18}$|⁠, which is lower than that of z ∼ 2 LAEs (1.8 ± 0.3) obtained by a previous study based on a three times smaller survey area, with a probability of 96%. However, the difference in the bias values can be explained if cosmic variance is taken into account. If such a low halo mass implies a low H i gas mass, this result appears to be consistent with the observations of a high Lyα escape fraction. With the low halo masses and ongoing star formation, our LAEs have a relatively high stellar-to-halo mass ratio (SHMR) and a high efficiency of converting baryons into stars. The extended Press–Schechter formalism predicts that at z = 0 our LAEs are typically embedded in halos with masses similar to that of the Large Magellanic Cloud (LMC); they will also have similar SHMRs to the LMC, if their star formation rates are largely suppressed after z ∼ 2 as some previous studies have reported for the LMC itself.

【 授权许可】

CC BY