Probing nuclear activity versus star formation at z ∼ 0.8 using near-infrared multi-object spectroscopy
Probing nuclear activity versus star formation at z ∼ 0.8 using near-infrared multi-object spectroscopy
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DOI：
10.1093/mnras/sts611
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发表时间：
2012-12
影响因子：
4.8
通讯作者：
C. R. Almeida;J. M. R. Espinosa;J. Acosta-Pulido;A. Alonso-Herrero;A. M. García;N. Rodŕiguez-Eugenio
中科院分区：
文献类型：
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作者：
C. R. Almeida;J. M. R. Espinosa;J. Acosta-Pulido;A. Alonso-Herrero;A. M. García;N. Rodŕiguez-Eugenio
我们在扩展生长带（EGS）中位红移为z ~ 0.8的28个x射线和中红外源的近红外（NIR）光谱观测。迄今为止，这是活动星系核（AGN）在这一红移处最大的近红外光谱汇编。数据采用4.2 m威廉·赫歇尔望远镜（WHT）长缝中分辨率红外光谱仪（LIRIS）的多目标光谱模式获得。这些星系代表了之前研究过的一个更大的样本，由超过100个x射线选择的源与中红外对应体组成，根据它们的光谱能量分布（SEDs）的形状，它们被分类为AGN主导或宿主星系主导。在这里，我们分别给出了13个和15个源的新近红外光谱。我们探测到大多数星系在连续统以上≥1.5σ处的Hα线。利用衰减校正的Hα光度和观测到的Spitzer/MIPS 24 μm通量，在减去AGN经验相关和多频SED拟合估计的AGN分量后，我们得到平均恒星形成率（SFRs）为7±7和20±-
We present near-infrared (NIR) spectroscopic observations of 28 X-ray and mid-infrared selected sources at a median redshift of z ∼ 0.8 in the Extended Groth Strip (EGS). To date this is the largest compilation of NIR spectra of active galactic nuclei (AGN) at this redshift. The data were obtained using the multi-object spectroscopic mode of the Long-slit Intermediate Resolution Infrared Spectrograph (LIRIS) at the 4.2 m William Herschel Telescope (WHT). These galaxies are representative of a larger sample studied in a previous work, consisting of over a hundred X-ray selected sources with mid-infrared counterparts, which were classified either as AGN dominated or host galaxy dominated, depending on the shape of their spectral energy distributions (SEDs). Here, we present new NIR spectra of 13 and 15 sources of each class, respectively. We detect the Hα line at ≥1.5σ above the continuum for the majority of the galaxies. Using attenuation-corrected Hα luminosities and observed Spitzer/MIPS 24 μm fluxes, and after subtracting an AGN component estimated using an AGN empirical correlation and multifrequency SED fits, we obtain average star formation rates (SFRs) of 7 ± 7 and 20 ± –