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arXiv 1004.1364astro-ph.GA
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局部发光红外星系。I. Spitzer/IRS空间分辨观测

Local Luminous Infrared Galaxies. I. Spatially resolved observations with Spitzer/IRS

Miguel Pereira-Santaella, Almudena Alonso-Herrero, George H. Rieke, Luis Colina, Tanio Diaz-Santos, J. -D. T. Smith, Pablo G. Perez-Gonzalez, Charles W. Engelbracht

摘要:

本文介绍了15个本地亮红外星系(LIRGs)的Spitzer/IRS光谱测绘观测结果。在本文中,我们研究了中红外发射的空间变化,其中包括:精细结构线,分子氢线,多环芳香族特征(PAHs),连续发射和9.7um硅酸盐特征。我们还比较了核谱和积分谱。我们发现,恒星形成发生在扩展区域(几个千秒差距)探测的PAH排放以及[NeII]和[NeIII]排放。积分PAH发射和9.7um硅酸盐特征的行为与本地星暴星系相似。我们还发现[NeIII]/[NeII]比值的最小值往往位于核处,其值低于我们LIRG和附近星系的HII区。这可能是在LIRG的核密度增加负责较小的核[NeIII]/[NeII]的比例。这包括一些质量最大的恒星仍然嵌入在超紧凑的HII区域的可能性。在我们的样品的大部分11.3 μ m的PAH发射似乎比尘埃5.5 μ m的连续发射更广泛。我们发现11.3 μ m PAH/7.7 μ m PAH和[NeII]/11.3 μ m PAH的比值与恒星星族的年龄有关。较小和较大的比值分别表明最近的恒星形成。估计的温暖(300 K < T < 1000 K)氢分子质量为10^8太阳质量,这与ULIRGs、局部星暴和塞弗特星系中发现的质量相似。最后,我们发现,[NeII]的速度场在我们的样本中的大多数LIRG是兼容的旋转盘在~kpc尺度,他们是在一个很好的协议与H-α速度场。

英文摘要:

We present results from the Spitzer/IRS spectral mapping observations of 15 local luminous infrared galaxies (LIRGs). In this paper we investigate the spatial variations of the mid-IR emission which includes: fine structure lines, molecular hydrogen lines, polycyclic aromatic features (PAHs), continuum emission and the 9.7um silicate feature. We also compare the nuclear and integrated spectra. We find that the star formation takes place in extended regions (several kpc) as probed by the PAH emission as well as the [NeII] and [NeIII] emissions. The behavior of the integrated PAH emission and 9.7um silicate feature is similar to that of local starburst galaxies. We also find that the minima of the [NeIII]/[NeII] ratio tends to be located at the nuclei and its value is lower than that of HII regions in our LIRGs and nearby galaxies. It is likely that increased densities in the nuclei of LIRGs are responsible for the smaller nuclear [NeIII]/[NeII] ratios. This includes the possibility that some of the most massive stars in the nuclei are still embedded in ultracompact HII regions. In a large fraction of our sample the 11.3um PAH emission appears more extended than the dust 5.5um continuum emission. We find a dependency of the 11.3um PAH/7.7 um PAH and [NeII]/11.3um PAH ratios with the age of the stellar populations. Smaller and larger ratios respectively indicate recent star formation. The estimated warm (300 K < T < 1000 K) molecular hydrogen masses are of the order of 10^8 M_Sun, which are similar to those found in ULIRGs, local starbursts and Seyfert galaxies. Finally we find that the [NeII] velocity fields for most of the LIRGs in our sample are compatible with a rotating disk at ~kpc scales, and they are in a good agreement with H-alpha velocity fields.

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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