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arXiv 2007.01878astro-ph.GAastro-ph.CO
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MUSE哈勃超深场巡天。XV。Ly-alpha发射体在z>3时的平均静止紫外光谱

The MUSE Hubble Ultra Deep Field Survey. XV. The mean rest-UV spectra of Ly-alpha emitters at z>3

Anna Feltre, Michael V. Maseda, Roland Bacon, Jayadev Pradeep, Floriane Leclercq, Haruka Kusakabe, Lutz Wisotzki, Takuya Hashimoto, Kasper B. Schmidt, Jeremy Bl… 展开作者

Anna Feltre, Michael V. Maseda, Roland Bacon, Jayadev Pradeep, Floriane Leclercq, Haruka Kusakabe, Lutz Wisotzki, Takuya Hashimoto, Kasper B. Schmidt, Jeremy Blaizot, Jarle Brinchmann, Leindert Boogaard, Sebastiano Cantalupo, David Carton, Hanae Inami, Wolfram Kollatschny, Raffaella A. Marino, Jorryt Matthee, Themiya Nanayakkara, Johan Richard, Joop Schaye, Laurence Tresse, Tanya Urrutia, Anne Verhamme, Peter M. Weilbacher

摘要:

我们研究了红移范围为2.9<z<4.6的微弱Lyman- $α$发射体(LAEs)的紫外(UV)光谱特性,为未来对微弱宇宙的观测提供了材料。我们使用MUSE哈勃超深巡天的数据来构建连续微弱(M $_{UV}$中位数为-18,低至M $_{UV}$为-16)、低恒星质量($10^{8.4}$中位数值,低至$10^{7}M_{\odot}$)的平均静止框架光谱红移z>3。我们计算LAEs的各种平均光谱,这些光谱是基于它们的观测结果(例如,Ly $α$强度、UV幅度和光谱斜率)和物理(例如,恒星质量和恒星形成率)属性。我们搜索的紫外光谱功能以外的LY $α$,如高电离星云发射线和吸收功能。我们成功地观察到OIII]1666和CIII]909碰撞激发的发射线和HeII 1640的复合特征,以及CIV 1550的共振双峰,无论是在发射还是P-Cygni。我们比较了观测到的不同平均光谱的光谱特性,发现发射线随LAEs的观测和物理特性而变化。特别是具有较大Ly $α$等效宽度、较暗UV星等、较蓝UV光谱斜率和较低恒星质量的LAEs的平均光谱显示出最强的星云发射。这些谱线的谱线比率与在局部贫金属星系光谱中测量到的相似,而它们的等效宽度与在z>2星系的个别光谱中检测到的少数极端值相比要弱。这表明弱紫外特征可能普遍存在于高z、低质量和微弱的LAE中。我们公开发布堆叠光谱,因为它们可以作为未来观测设计的经验模板,例如詹姆斯韦伯太空望远镜和超大望远镜。

英文摘要:

We investigate the ultraviolet (UV) spectral properties of faint Lyman-$α$ emitters (LAEs) in the redshift range 2.9<z<4.6 and provide material to prepare future observations of the faint Universe. We use data from the MUSE Hubble Ultra Deep Survey to construct mean rest-frame spectra of continuum-faint (median M$_{UV}$ of -18 and down to M$_{UV}$ of -16), low stellar mass (median value of $10^{8.4}$ and down to $10^{7}M_{\odot}$) LAEs at redshift z>3. We compute various averaged spectra of LAEs sub-sampled on the basis of their observational (e.g., Ly$α$ strength, UV magnitude and spectral slope) and physical (e.g., stellar mass and star-formation rate) properties. We search for UV spectral features other than Ly$α$, such as higher-ionization nebular emission lines and absorption features. We successfully observe the OIII]1666 and CIII]909 collisionally excited emission lines and the HeII1640 recombination feature, as well as the resonant CIV1550 doublet either in emission or P-Cygni. We compare the observed spectral properties of the different mean spectra and find the emission lines to vary with the observational and physical properties of the LAEs. In particular, the mean spectra of LAEs with larger Ly$α$ equivalent widths, fainter UV magnitudes, bluer UV spectral slopes and lower stellar masses show the strongest nebular emission. The line ratios of these lines are similar to those measured in the spectra of local metal-poor galaxies, while their equivalent widths are weaker compared to the handful of extreme values detected in individual spectra of z>2 galaxies. This suggests that weak UV features are likely ubiquitous in high z, low-mass and faint LAEs. We publicly release the stacked spectra as they can serve as empirical templates for the design of future observations, such as those with the James Webb Space Telescope and the Extremely Large Telescope.

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