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arXiv 1107.5958astro-ph.CO
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中红外波段(U)激光诱导光栅的空间范围II。特征发射

The Spatial Extent of (U)LIRGs in the Mid-Infrared. II. Feature Emission

Tanio Diaz-Santos, Vassilis Charmandaris, Lee Armus, Sabrina Stierwalt, Sebastian Haan, Joseph Mazzarella, Justin Howell, Sylvain Veilleux, Eric Murphy, Andreea… 展开作者

Tanio Diaz-Santos, Vassilis Charmandaris, Lee Armus, Sabrina Stierwalt, Sebastian Haan, Joseph Mazzarella, Justin Howell, Sylvain Veilleux, Eric Murphy, Andreea Petric, Philip N. Appleton, Aaron S. Evans, David Sanders, Jason Surace

摘要:

我们目前的结果,从我们的扩展中红外(MIR)发射的大天文台全天LIRG调查(GOALS)样本的分析的第二部分的基础上获得的5-14微米的低分辨率光谱与斯皮策的IRS。我们计算扩展发射的分数作为样本中所有星系的波长的函数,FEE_lambda,并在空间上分离的MIR光谱的星系到它们的核和扩展组件。我们发现,[NeII]的发射线是紧凑的热尘埃MIR连续,而多环芳烃(PAH)的排放更延长。6.2和7.7微米的PAH发射比11.3微米的PAH发射更紧凑,这与前者在更电离的介质中增强一致。活动星系核或一个强大的核爆发的存在下,增加了紧凑的热尘埃MIR连续,但有一个可以忽略不计的影响的空间范围内的多环芳烃排放的kpc尺度。在全球范围内,扩展发射分量的光谱是均匀的所有星系在GOALS。这表明,在距离(U)LIRGs核1.5 kpc以上的地方,恒星形成的物理性质非常相似,类似于L_IR < 10^11 Lsun的局部恒星形成星系,以及z~2处以恒星形成为主的ULIRGs。相比之下,本地(U)LIRGs的核组分的MIR光谱是非常多样化的。这意味着,所观察到的各种综合MIR性能的出现,平均而言,只有从正在发生的过程中,在他们的核心。

英文摘要:

We present results from the second part of our analysis of the extended mid-infrared (MIR) emission of the Great Observatories All-Sky LIRG Survey (GOALS) sample based on 5-14 micron low-resolution spectra obtained with the IRS on Spitzer. We calculate the fraction of extended emission as a function of wavelength for all galaxies in the sample, FEE_lambda, and spatially separate the MIR spectrum of galaxies into their nuclear and extended components. We find that the [NeII] emission line is as compact as the hot dust MIR continuum, while the polycyclic aromatic hydrocarbon (PAH) emission is more extended. The 6.2 and 7.7 micron PAH emission is more compact than that of the 11.3 micron PAH, which is consistent with the formers being enhanced in a more ionized medium. The presence of an AGN or a powerful nuclear starburst increases the compactness of the hot dust MIR continuum, but has a negligible effect on the spatial extent of the PAH emission on kpc-scales. Globally, the spectra of the extended emission component are homogeneous for all galaxies in GOALS. This suggests that the physical properties of star formation taking place at distances farther than 1.5 kpc from the nuclei of (U)LIRGs are very similar, resembling local star-forming galaxies with L_IR < 10^11 Lsun, as well as star formation-dominated ULIRGs at z~2. In contrast, the MIR spectra of the nuclear component of local (U)LIRGs are very diverse. This implies that the observed variety of their integrated MIR properties arise, on average, only from the processes that are taking place in their cores.

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