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arXiv 1209.0670astro-ph.CO
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Herschel-ATLAS:宽吸收线类恒星天体的远红外特性和恒星形成率

Herschel-ATLAS: the far-infrared properties and star-formation rates of broad absorption line quasi-stellar objects

J. M. Cao Orjales, J. A. Stevens, M. J. Jarvis, D. J. B. Smith, M. J. Hardcastle, R. Auld, M. Baes, A. Cava, D. L. Clements, A. Cooray, K. Coppin, A. Dariush, G… 展开作者

J. M. Cao Orjales, J. A. Stevens, M. J. Jarvis, D. J. B. Smith, M. J. Hardcastle, R. Auld, M. Baes, A. Cava, D. L. Clements, A. Cooray, K. Coppin, A. Dariush, G. De Zotti, L. Dunne, S. Dye, S. Eales, R. Hopwood, C. Hoyos, E. Ibar, R. J. Ivison, S. Maddox, M. J. Page, E. Valiante

摘要:

利用Herschel-ATLAS在250、350和500 μm波段的观测数据,对50个宽吸收线类星体(BAL类星体)的远红外(FIR)特性进行了测量。我们的样本包含49个高电离BAL类星体(HiBALs)和1个低电离BAL类星体(LoBAL),与329个非BAL类星体的样本进行比较。这些样本在红移范围1.5 \leq z < 2.3上匹配,并且在范围-28 \leq M_{i} \leq-24上在绝对i带幅度上匹配。其中,3个BAL类星体(HiBALs)和27个非BAL类星体在> 5 sigma水平被检测到。我们计算我们单独检测到的HiBAL类星体和未检测到的LoBAL类星体的恒星形成率(SFR),以及BAL和非BAL类星体样本的平均SFR的基础上堆叠的赫歇尔数据。我们发现没有差异的HiBAL和非BAL类星体样本在FIR中,即使分离基于不同的BAL类星体分类。使用Mrk 231作为模板,估计整个样本的加权平均SFR为\approx 240 \pm 21 M_{\odot} yr^{-1},尽管如果活动星系核加热的尘埃对远红外辐射有贡献,这个数字应该被视为上限。尽管在文献中的暂定索赔,我们没有找到一个依赖{ \sc C\,IV}的FIR发射等效宽度,这表明在这些对象中的任何流出的强度是不链接到他们的FIR输出。这些结果强烈表明,BAL类星体(更具体地说,HiBALs)可以容纳在一个简单的活动星系核统一计划,我们的视线的核心相交流出的物质。模型中,HiBALs被捕获到一个时期的增强球体和黑洞的增长,在此期间,风终止恒星形成活动的结束,不支持所观察到的FIR特性。

英文摘要:

We have used data from the Herschel-ATLAS at 250, 350 and 500 μm to determine the far-infrared (FIR) properties of 50 Broad Absorption Line Quasars (BAL QSOs). Our sample contains 49 high-ionization BAL QSOs (HiBALs) and 1 low-ionization BAL QSO (LoBAL) which are compared against a sample of 329 non-BAL QSOs. These samples are matched over the redshift range 1.5 \leq z < 2.3 and in absolute i-band magnitude over the range -28 \leq M_{i} \leq -24. Of these, 3 BAL QSOs (HiBALs) and 27 non-BAL QSOs are detected at the > 5 sigma level. We calculate star-formation rates (SFR) for our individually detected HiBAL QSOs and the non-detected LoBAL QSO as well as average SFRs for the BAL and non-BAL QSO samples based on stacking the Herschel data. We find no difference between the HiBAL and non-BAL QSO samples in the FIR, even when separated based on differing BAL QSO classifications. Using Mrk 231 as a template, the weighted mean SFR is estimated to be \approx240\pm21 M_{\odot} yr^{-1} for the full sample, although this figure should be treated as an upper limit if AGN-heated dust makes a contribution to the FIR emission. Despite tentative claims in the literature, we do not find a dependence of {\sc C\,iv} equivalent width on FIR emission, suggesting that the strength of any outflow in these objects is not linked to their FIR output. These results strongly suggest that BAL QSOs (more specifically HiBALs) can be accommodated within a simple AGN unified scheme in which our line-of-sight to the nucleus intersects outflowing material. Models in which HiBALs are caught towards the end of a period of enhanced spheroid and black-hole growth, during which a wind terminates the star-formation activity, are not supported by the observed FIR properties.

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