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arXiv 1108.3229astro-ph.CO
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宇宙时间内星暴星系中超大质量黑洞的生长:来自最深Chandra场的约束

Supermassive Black Hole Growth in Starburst Galaxies over Cosmic Time: Constraints from the Deepest Chandra Fields

D. A. Rafferty, W. N. Brandt, D. M. Alexander, Y. Q. Xue, F. E. Bauer, B. D. Lehmer, B. Luo, C. Papovich

摘要:

本文分析了扩展钱德拉深场南带和扩展Groth带中z ~ 0.3-3星暴星系的深多波长数据。我们确定活动星系核(AGN)在这些红外线源,通过它们的X射线发射和量化的分数,主机的AGN。我们发现这一比例强烈依赖于光源的中红外颜色和静止帧中红外光度,在最温暖的颜色和最高的中红外光度(对应于超亮红外星系)时上升到~ 50-70%,与当地发现的趋势相似。此外,我们还发现活动星系核的比例强烈地依赖于宿主星系的恒星形成率(由观测到的70 μ m光度减去活动星系核的贡献后推断),特别是对于更明亮的活动星系核(LX> 10^43 erg/s)。在最高的恒星形成率(~ 1000 M_sun/yr)下,X射线探测到活动星系核的星系比例上升到~ 30%,与高红移亚毫米星系中发现的情况大致一致。假设活动星系核部分是由恒星形成率驱动的,(而不是恒星质量或红移,我们的样本在很大程度上是简并的),这个结果意味着发光活动星系核活动的占空比随着宿主星系的恒星形成率而增加:具体地说,我们发现,在恒星形成率高的系统中,X射线探测到的活动星系核至少要多出5-10倍(> 300 M_sun/yr)比低恒星形成率(< 30 M_sun/yr)的系统更容易形成。最后,我们调查之间的比率超大质量黑洞吸积率和宿主星系的增长率,并发现,源与检测活动星系核和恒星形成,这个比率在遥远的星爆同意以及从本地的标度关系假设的黑洞和凸起生长在同一时期的预期。

英文摘要:

We present an analysis of deep multiwavelength data for z ~ 0.3-3 starburst galaxies selected by their 70 um emission in the Extended-Chandra Deep Field-South and Extended Groth Strip. We identify active galactic nuclei (AGNs) in these infrared sources through their X-ray emission and quantify the fraction that host an AGN. We find that the fraction depends strongly on both the mid-infrared color and rest-frame mid-infrared luminosity of the source, rising to ~ 50-70% at the warmest colors and highest mid-infrared luminosities (corresponding to ultraluminous infrared galaxies), similar to the trends found locally. Additionally, we find that the AGN fraction depends strongly on the star formation rate of the host galaxy (inferred from the observed 70 um luminosity after subtracting the estimated AGN contribution), particularly for more luminous AGNs (L_X > 10^43 erg/s). At the highest star formation rates (~ 1000 M_sun/yr), the fraction of galaxies with an X-ray detected AGN rises to ~ 30%, roughly consistent with that found in high-redshift submillimeter galaxies. Assuming that the AGN fraction is driven by the star formation rate (rather than stellar mass or redshift, for which our sample is largely degenerate), this result implies that the duty cycle of luminous AGN activity increases with the star formation rate of the host galaxy: specifically, we find that luminous X-ray detected AGNs are at least ~ 5-10 times more common in systems with high star formation rates (> 300 M_sun/yr) than in systems with lower star formation rates (< 30 M_sun/yr). Lastly, we investigate the ratio between the supermassive black hole accretion rate and the growth rate of the host galaxy and find that, for sources with detected AGNs and star formation, this ratio in distant starbursts agrees well with that expected from the local scaling relation assuming the black holes and bulges grew at the same epoch.

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