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arXiv 1503.01753astro-ph.GA
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VIMOS超深巡天:2<z<2.5恒星形成星系的Ly $α$发射和恒星星族

The VIMOS Ultra Deep Survey: Ly$α$ Emission and Stellar Populations of Star-Forming Galaxies at 2<z<2.5

Nimish P. Hathi, O. Le Fèvre, O. Ilbert, P. Cassata, L. A. M. Tasca, B. C. Lemaux, B. Garilli, V. Le Brun, D. Maccagni, L. Pentericci, R. Thomas, E. Vanzella, G… 展开作者

Nimish P. Hathi, O. Le Fèvre, O. Ilbert, P. Cassata, L. A. M. Tasca, B. C. Lemaux, B. Garilli, V. Le Brun, D. Maccagni, L. Pentericci, R. Thomas, E. Vanzella, G. Zamorani, E. Zucca, R. Amorín, S. Bardelli, L. P. Cassarà, M. Castellano, A. Cimatti, O. Cucciati, A. Durkalec, A. Fontana, M. Giavalisco, A. Grazian, L. Guaita, A. Koekemoer, S. Paltani, J. Pforr, B. Ribeiro, D. Schaerer, M. Scodeggio, V. Sommariva, M. Talia, L. Tresse, D. Vergani, P. Capak, S. Charlot, T. Contini, J. G. Cuby, S. de la Torre, J. Dunlop, S. Fotopoulou, C. López-Sanjuan, Y. Mellier, M. Salvato, N. Scoville, Y. Taniguchi, P. W. Wang

摘要:

利用VIMOS超深巡天(VUDS)的光谱数据和三个广泛研究的河外星系场(ECDFS,VVDS,COSMOS)的深多波长光度数据,研究了854个2<z<2.5的暗($i_{AB}$ <~25等)成星星系(SFG)的光谱和光度特性。这些SFG是基于它们的光度红移的光谱学的目标。VUDS光谱用于测量UV光谱斜率($β$)以及Ly $α$等效宽度(EW)。平均而言,光谱测量的$β$(-1.36 $\pm$ 0.02)与光度测量的$β$(-1.32 $\pm$ 0.02)相当,并且具有较小的测量不确定性。正相关的$β$与光谱能量分布(SED)为基础的测量尘埃消光,E $_{\rm s}$(B-V),强调的重要性$β$作为一个替代的尘埃指标在高红移。为了进行适当的比较,我们根据这些SFG的静止框架Ly $α$ EW将这些SFG分为三个亚组:无Ly $α$发射的SFG(SFG $_{\rm N}$ ; EW $\le$ 0),有Ly $α$发射的SFG(SFG $_{\rm L}$ ; EW $>$ 0)和Ly $α$发射的SFG(LAE; EW $\ge$ 20)。在这些红移的LAEs的分数是$\sim$ 10%,这是与以前的观察一致。我们比较了SFG $_{\rm N}$、SFG $_{\rm L}$和LAE样本的最佳拟合SED估计恒星参数。对于这里探测的光度($\sim$ L $^*$),我们发现,星系与没有Ly $α$的发射有很小的,但显着的差异,在他们的SED为基础的属性。我们发现,LAEs有更少的尘埃,和较低的恒星形成率(SFR)相比,非LAEs。我们还发现,LAE的质量比非LAE小,尽管与SFR和E $_{\rm s}$(B-V)相比,差异较小且不太显著。[删节]

英文摘要:

The aim of this paper is to investigate spectral and photometric properties of 854 faint ($i_{AB}$<~25 mag) star-forming galaxies (SFGs) at 2<z<2.5 using the VIMOS Ultra-Deep Survey (VUDS) spectroscopic data and deep multi-wavelength photometric data in three extensively studied extragalactic fields (ECDFS, VVDS, COSMOS). These SFGs were targeted for spectroscopy based on their photometric redshifts. The VUDS spectra are used to measure the UV spectral slopes ($β$) as well as Ly$α$ equivalent widths (EW). On average, the spectroscopically measured $β$ (-1.36$\pm$0.02), is comparable to the photometrically measured $β$ (-1.32$\pm$0.02), and has smaller measurement uncertainties. The positive correlation of $β$ with the Spectral Energy Distribution (SED)-based measurement of dust extinction, E$_{\rm s}$(B-V), emphasizes the importance of $β$ as an alternative dust indicator at high redshifts. To make a proper comparison, we divide these SFGs into three subgroups based on their rest-frame Ly$α$ EW: SFGs with no Ly$α$ emission (SFG$_{\rm N}$; EW$\le$0Å), SFGs with Ly$α$ emission (SFG$_{\rm L}$; EW$>$0Å), and Ly$α$ emitters (LAEs; EW$\ge$20Å). The fraction of LAEs at these redshifts is $\sim$10%, which is consistent with previous observations. We compared best-fit SED-estimated stellar parameters of the SFG$_{\rm N}$, SFG$_{\rm L}$ and LAE samples. For the luminosities probed here ($\sim$L$^*$), we find that galaxies with and without Ly$α$ in emission have small but significant differences in their SED-based properties. We find that LAEs have less dust, and lower star-formation rates (SFR) compared to non-LAEs. We also find that LAEs are less massive compared to non-LAEs, though the difference is smaller and less significant compared to the SFR and E$_{\rm s}$(B-V). [abridged]

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