The stellar mass, star formation rate and dark matter halo properties of LAEs at z ∼ 2. (13th January 2018)

• Record Type: Journal Article
• Authors: Kusakabe, Haruka; Shimasaku, Kazuhiro; Ouchi, Masami; Nakajima, Kimihiko; Goto, Ryosuke; Hashimoto, Takuya; Konno, Akira; Harikane, Yuichi; Silverman, John D; Capak, Peter L
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 70:Number 1(2018:Feb.)
• Publication Date: 2018-01-13
• Subjects: galaxies: evolution -- galaxies: halos -- galaxies: high-redshift -- galaxies: star formation; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psx148
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: 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 deg 2 in total. With an average stellar mass of 10.2 ± 1.8 × 10 8 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 SHMR s to the LMC, if their star formation rates are largely suppressed after z ∼ 2 as some previous studies have reported for the LMC itself.