Molecular gas content in obscured AGN at z > 1
Molecular gas content in obscured AGN at z > 1
复制标题
DOI：
10.1051/0004-6361/201833040
复制
发表时间：
2018-07
影响因子：
6.5
通讯作者：
M. Perna;M. Sargent;M. Brusa;E. Daddi;C. Feruglio;G. Cresci;G. Lanzuisi;E. Lusso;A. Comastri
中科院分区：
文献类型：
--
作者：
M. Perna;M. Sargent;M. Brusa;E. Daddi;C. Feruglio;G. Cresci;G. Lanzuisi;E. Lusso;A. Comastri
目标。标准的活动星系核(AGN)-星系共同演化方案预测，在反馈现象耗尽星系的冷分子气库并揭示出光学发光类星体(QSO)之前，将出现一个“深埋”的超大质量黑洞增长与恒星爆发(Sb)共存的阶段(称为Sb-QSO演化序列)。这项工作的目的是测量三个高度遮挡的类星体的冷气藏，以测试它们的气体分数是否如一些模型所预期的那样类似于亚毫米星系(SMGs)，并将这些测量置于SB-QSO框架的背景下。方法：研究方法。我们的目标是BzK4892中的CO(1-0)跃迁，z=2.6时的康普顿厚(CT)类星体，BzK8608中的CO(1-0)和CDF153中的CO(2-1)，以及z=2.5时的两个高度遮蔽的(NH≈6×1023 cm−2)类星体。对于这些目标，我们在CO谱线上设置了3个σ上限，其中L的CO1考虑了正常的恒星形成星系和SMG，以及文献中未遮挡和遮挡的活动星系核。对于AGN样本，我们提供了最新的和几乎完整的靶点集合，并在z>；1进行了CO随访。BzK4892显示出高的恒星形成效率(SFE=LiR/L的Co>；410 L⊙/(K KM S−1PC2))和气体分数FGA=MGA/(MSTAR+MGA)10 L⊙/(K KM S−1PC2)。通过与文献资料的比较，我们发现：平均而言，与正常的恒星形成星系和恒星群相比，在z>；1处遮挡的活动星系核具有更高的SFE和更低的FGA；ii)轻度和高度遮挡的活动星系具有相似的气体分数；iii)CT和遮蔽AGN的SFE与未遮挡的AGN相似。结论。在SB-QSO框架内，这些发现可能与反馈可能从SB-QSO演化序列的早期阶段就已经影响到宿主星系的情况一致。
Aims. The standard active galactic nuclei (AGN)-galaxy co-evolutionary scenario predicts a phase of deeply “buried” supermassive black hole growth coexisting with a starburst (SB) before feedback phenomena deplete the cold molecular gas reservoir of the galaxy and an optically luminous quasar (QSO) is revealed (called the SB-QSO evolutionary sequence). The aim of this work is to measure the cold gas reservoir of three highly obscured QSOs to test if their gas fraction is similar to that of submillimetre galaxies (SMGs), as expected by some models, and to place these measurements in the context of the SB-QSO framework. Methods. We target CO(1-0) transition in BzK4892, a Compton thick (CT) QSO at z = 2.6, CO(1-0) in BzK8608 and CO(2-1) in CDF153, two highly obscured (NH ≈ 6 × 1023 cm−2) QSOs at z = 2.5 and z = 1.5, respectively. For these targets, we place 3σ upper limits on the CO lines, with L′CO 1, considering normal star-forming galaxies and SMGs, and unobscured and obscured AGN from the literature. For the AGN samples, we provide an updated and almost complete collection of targets with CO follow-up at z > 1. Results. BzK4892 displays a high star formation efficiency (SFE = LIR/L′CO > 410 L⊙/(K km s−1 pc2 )) and a gas fraction fgas = Mgas/(Mstar + Mgas) 10 L⊙/(K km s−1 pc2 )). From the comparison with the literature data we found that, on average, i) obscured AGN at z > 1 are associated with higher SFE and lower fgas with respect to normal star-forming galaxies and SMGs; ii) mildly and highly obscured active galaxies have comparable gas fractions; iii) the SFE of CT and obscured AGN are similar to those of unobscured AGN. Conclusions. Within the SB-QSO framework, these findings could be consistent with a scenario where feedback can impact the host galaxy already from the early phases of the SB-QSO evolutionary sequence.