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arXiv 1301.4015astro-ph.CO
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局部发光红外星系。III。黑洞生长与恒星形成活动的协同演化

Local Luminous Infrared Galaxies. III. Co-evolution of Black Hole Growth and Star Formation Activity?

Almudena Alonso-Herrero, Miguel Pereira-Santaella, George H. Rieke, Aleksandar M. Diamond-Stanic, Yiping Wang, Antonio Hernan-Caballero, Dimitra Rigopoulou

摘要:

本机亮红外(IR)星系(LIRGs)既有高恒星形成率(SFR)和高AGN(Seyfert和AGN/星暴复合)的入射。因此,它们是探索黑洞(BH)生长和恒星形成(SF)活动共同演化的理想候选者,不一定与重大合并有关。在这里,我们使用斯皮策/IRS光谱的一个完整的体积有限的本地LIRGs(距离<78 Mpc)的样本。我们利用[NeIII] 15.56微米和光学[OIII] 5007 A气体速度色散和文献中的恒星速度色散估计了3 × 10^7 M_sun的典型BH质量。我们发现,在大部分的本地LIRGs目前的SFR不仅发生在内核~1.5kpc的区域,从核11.3微米PAH光度估计,但也在宿主星系。接下来,我们使用的SFR和BH吸积率(BHAR)之间的比率,研究是否SF活动和BH的增长是同时在本地LIRGs。平均而言,本地LIRG的SFR BHAR比高于那些光学选择的赛弗类似AGN光度。然而,RSA Seyfert样本中的大多数红外亮星系表现得像本地LIRG。此外,AGN的发病率往往是较高的本地LIRG与最低的SFR。所有这些都表明,在局部LIRGs中,在当前BH生长的大部分之前发生了一个明显的IR亮星形成阶段(即,AGN阶段)。后者首先被反映为一个复合物,然后作为一个塞弗特,后来作为一个非LIRG光学识别的塞弗特核与中等SF在其宿主星系。

英文摘要:

Local luminous infrared (IR) galaxies (LIRGs) have both high star formation rates (SFR) and a high AGN (Seyfert and AGN/starburst composite) incidence. Therefore, they are ideal candidates to explore the co-evolution of black hole (BH) growth and star formation (SF) activity, not necessarily associated with major mergers. Here, we use Spitzer/IRS spectroscopy of a complete volume-limited sample of local LIRGs (distances of <78Mpc). We estimate typical BH masses of 3x10^7 M_sun using [NeIII]15.56micron and optical [OIII]5007A gas velocity dispersions and literature stellar velocity dispersions. We find that in a large fraction of local LIRGs the current SFR is taking place not only in the inner nuclear ~1.5kpc region, as estimated from the nuclear 11.3micron PAH luminosities, but also in the host galaxy. We next use the ratios between the SFRs and BH accretion rates (BHAR) to study whether the SF activity and BH growth are contemporaneous in local LIRGs. On average, local LIRGs have SFR to BHAR ratios higher than those of optically selected Seyferts of similar AGN luminosities. However, the majority of the IR-bright galaxies in the RSA Seyfert sample behave like local LIRGs. Moreover, the AGN incidence tends to be higher in local LIRGs with the lowest SFRs. All this suggests that in local LIRGs there is a distinct IR-bright star forming phase taking place prior to the bulk of the current BH growth (i.e., AGN phase). The latter is reflected first as a composite and then as a Seyfert, and later as a non-LIRG optically identified Seyfert nucleus with moderate SF in its host galaxy.

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