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arXiv 0907.1236astro-ph.CO
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用5-8微米光谱探测局部超铝红外星系的活动星系核和星暴含量

Exploring the active galactic nucleus and starburst content of local ultraluminous infrared galaxies through 5-8 micron spectroscopy

E. Nardini, G. Risaliti, M. Salvati, E. Sani, Y. Watabe, A. Marconi, R. Maiolino

摘要:

本文对71个红移z < 0.15的超亮红外星系(ULIRGs)的Spitzer-IRS光谱进行了5-8 μ m的分析,研究了活动星系核(AGN)和星暴(SB)作为极红外辐射动力源的作用。大约5微米的活动星系核比相同辐射光度的恒星暴增亮得多(30倍)。这使我们能够检测到ULIRGs内部甚至微弱的吸积驱动核心的存在:在我们的样本中有70%(50/71来源)发现了AGN活动的特征。通过一个简单的分析模型,我们也能够得到一个定量的估计AGN/SB的贡献,每个源的总能量输出。虽然ULIRG光度的主要部分被证实来自恒星形成事件,活动星系核的贡献是不可忽略的(23%),并显示出与光度增加。一个相当异构的模式中的组成和几何结构的尘埃ULIRGs之间的存在是新的支持个人的吸收功能和连续消光之间的比较。

英文摘要:

We present a 5-8 micron analysis of the Spitzer-IRS spectra of 71 ultraluminous infrared galaxies (ULIRGs) with redshift z < 0.15, devoted to the study of the role of active galactic nuclei (AGN) and starbursts (SB) as the power source of the extreme infrared emission. Around 5 micron an AGN is much brighter (by a factor 30) than a starburst of equal bolometric luminosity. This allows us to detect the presence of even faint accretion-driven cores inside ULIRGs: signatures of AGN activity are found in 70 per cent of our sample (50/71 sources). Through a simple analytical model we are also able to obtain a quantitative estimate of the AGN/SB contribution to the overall energy output of each source. Although the main fraction of ULIRG luminosity is confirmed to arise from star formation events, the AGN contribution is non-negligible (23 per cent) and is shown to increase with luminosity. The existence of a rather heterogeneous pattern in the composition and geometrical structure of the dust among ULIRGs is newly supported by the comparison between individual absorption features and continuum extinction.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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