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arXiv 1803.08045astro-ph.GA
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SHARDS巡天中的低红移恒星形成星系

Star-forming galaxies at low-redshift in the SHARDS survey

A. Lumbreras-Calle, C. Muñoz-Tuñón, J. Méndez-Abreu, J. M. Mas-Hesse, P. G. Pérez-González, B. Alcalde Pampliega, P. Arrabal Haro, A. Cava, H. Domínguez Sánchez… 展开作者

A. Lumbreras-Calle, C. Muñoz-Tuñón, J. Méndez-Abreu, J. M. Mas-Hesse, P. G. Pérez-González, B. Alcalde Pampliega, P. Arrabal Haro, A. Cava, H. Domínguez Sánchez, M. C. Eliche-Moral, A. Alonso-Herrero, A. Borlaff, J. Gallego, A. Hernán-Caballero, A. M. Koekemoer, L. Rodríguez-Muñoz

摘要:

驱动星系恒星形成(SF)在宇宙时间演化的物理过程仍然存在许多悬而未决的问题。最近的星系巡天使得我们能够在中等红移下详细研究这些过程。在这项工作中,我们建立了一个完整的恒星形成星系的样本,并分析了它们的性质,达到低恒星质量和低恒星形成率(SFR)在中低红移的系统。我们使用的数据从SHARDS多波段调查在GOODS北字段。它的深度(可达$\langle m_{3σ}\rangle\sim26.5$等)和分光光度分辨率($R\sim50$)为我们提供了一个理想的数据集来搜索发射线星系(ELG)。我们发展了一种新的算法,通过同时检测[OIII]5007和$Hα$发射线来识别低红移($z$ <0.36)ELG。我们使用两个单一恒星星族的模型拟合所选样本的光谱能量分布(SED)。我们发现了160个恒星形成星系的等效宽度(EW)低至12,样本的中值$\sim$ 35在[OIII]5007和$\sim$ 56在$Hα$,分别。SED拟合的结果显示了一个年轻的恒星群体,具有较低的中值金属丰度(太阳值的36%)和消光($A_V \sim$ 0.37),中值星系恒星质量为$\sim$ 10 $^{8.5}$ M $_{\odot}$。从现有光谱测量的气相金属丰度也很低。我们样本中的ELG在UVJ平面上呈现出比SHARDS中的中值颜色选择恒星形成星系更蓝的颜色。我们提出了一个新的(V-J)颜色标准,以区分ELG从非ELG在蓝色星系样本。此外,有几个星系存在高密度的O型恒星。只有在包含老恒星群的情况下,才能得到与完整SED的稳健拟合,这表明年轻恒星群是由一个老星系中最近爆发的SF形成的。

英文摘要:

The physical processes driving the evolution of star formation (SF) in galaxies over cosmic time still present many open questions. Recent galaxy surveys allow now to study these processes in great detail at intermediate redshift. In this work, we build a complete sample of star-forming galaxies and analyze their properties, reaching systems with low stellar masses and low star formation rates (SFRs) at intermediate-to-low redshift. We use data from the SHARDS multiband survey in the GOODS-North field. Its depth (up to magnitude $\langle m_{3σ}\rangle\sim26.5$) and its spectro-photometric resolution ($R\sim50$) provides us with an ideal dataset to search for emission line galaxies (ELGs). We develop a new algorithm to identify low-redshift ($z$<0.36) ELGs by detecting the [OIII]5007 and $Hα$ emission lines simultaneously. We fit the spectral energy distribution (SED) of the selected sample, using a model with two single stellar populations. We find 160 star-forming galaxies with equivalent widths (EWs) as low as 12 Å, with median values for the sample of $\sim$ 35 Å in [OIII]5007 and $\sim$ 56 Å in $Hα$, respectively. Results from the SED fitting show a young stellar population with low median metallicity (36% of the solar value) and extinction ($A_V \sim$ 0.37), with median galaxy stellar mass $\sim$ 10$^{8.5}$ M$_{\odot}$. Gas-phase metallicities measured from available spectra are also low. ELGs in our sample present bluer colors in the UVJ plane than the median color-selected star-forming galaxy in SHARDS. We suggest a new (V-J) color criterion to separate ELGs from non-ELGs in blue galaxy samples. In addition, several galaxies present high densities of O-type stars. Robust fits to the full SEDs can only be obtained including an old stellar population, suggesting the young component is built up by a recent burst of SF in an otherwise old galaxy.

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