arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1007.1676astro-ph.COastro-ph.GA
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南方2MASS AGN巡天:6 dF光谱跟踪

The Southern 2MASS AGN Survey: spectroscopic follow-up with 6dF

Frank Masci, Roc Cutri, Paul Francis, Brant Nelson, John Huchra, D. Heath Jones, Matthew Colless, Will Saunders

摘要:

两微米全天巡天计划(2MASS)提供了一个统一的光度表,以寻找以前未知的红色活动星系核和类星体。我们已经扩大了搜索南赤道天空获得光谱的1182 AGN候选人使用英国施密特望远镜的6dF多光纤摄谱仪。这些目标被安排作为6dF星系红移巡天的辅助目标。候选者是使用J-Ks> 2到Ks~15.5的单色切割和|b|> 30度的银河纬度来选择的。432个光谱的质量足以进行可靠的分类。116个(约27%)源被安全地分类为1型活动星系核,20个可能为1型,57个可能为2型。它们中的大多数跨越红移范围0.05 <z <0.5,只有8个(约6%)以前被确认为活动星系核或类星体。我们的选择导致一个显着更高的AGN识别率在本地星系(> 20%)比任何以前的星系调查。一小部分第1型活动星系核的光学颜色可以被相对于光学选择类星体的A_V <2等的光学薄尘埃变红。少数显示出过量远红外辐射的证据。第1型和第2型活动星系核的等效宽度和颜色分布与活动星系核统一模型一致。特别是,EW的[OIII]发射线弱相关的光学-近红外颜色在每一类活动星系核,这表明各向异性的活动星系核的连续性。总的来说,2MASS红色活动星系核的光学性质与光学选择类星体的光学性质没有显著的不同。我们的近红外选择似乎检测到最近红外发光的类星体在当地的宇宙z~0.6,并提供激励,以扩大搜索到更深的近红外调查。

英文摘要:

The Two Micron All-Sky Survey (2MASS) has provided a uniform photometric catalog to search for previously unknown red AGN and QSOs. We have extended the search to the southern equatorial sky by obtaining spectra for 1182 AGN candidates using the 6dF multifibre spectrograph on the UK Schmidt Telescope. These were scheduled as auxiliary targets for the 6dF Galaxy Redshift Survey. The candidates were selected using a single color cut of J - Ks > 2 to Ks ~ 15.5 and a galactic latitude of |b|>30 deg. 432 spectra were of sufficient quality to enable a reliable classification. 116 sources (or ~27%) were securely classified as type 1 AGN, 20 as probable type 1s, and 57 as probable type 2 AGN. Most of them span the redshift range 0.05<z<0.5 and only 8 (or ~6%) were previously identified as AGN or QSOs. Our selection leads to a significantly higher AGN identification rate amongst local galaxies (>20%) than in any previous galaxy survey. A small fraction of the type 1 AGN could have their optical colors reddened by optically thin dust with A_V<2 mag relative to optically selected QSOs. A handful show evidence for excess far-IR emission. The equivalent width (EW) and color distributions of the type 1 and 2 AGN are consistent with AGN unified models. In particular, the EW of the [OIII] emission line weakly correlates with optical--near-IR color in each class of AGN, suggesting anisotropic obscuration of the AGN continuum. Overall, the optical properties of the 2MASS red AGN are not dramatically different from those of optically-selected QSOs. Our near-IR selection appears to detect the most near-IR luminous QSOs in the local universe to z~0.6 and provides incentive to extend the search to deeper near-IR surveys.

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