Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields
Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields
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欧洲大面积 ISO 巡天区域恒星形成星系的近红外和中红外颜色
DOI：
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发表时间：
2002
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通讯作者：
E. Tollestrup
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作者：
P. Vaisanen;T. Morel;M. Rowan‐Robinson;S. Serjeant;S. Oliver;T. Sumner;H. Crockett;C. Gruppioni;E. Tollestrup
本文介绍了作为欧洲大面积ISO调查(ELAIS)的一部分的红外空间天文台(ISO)探测到的中红外(MID-IR)源样本的J-波段和K-波段近红外(Near-IR)光度测量，并研究了它们的分类和恒星形成特性。我们已经使用了6.7微米(LW2)和15微米(LW3)通量的ELAIS初步目录。所有高可靠的LW2源和80%的LW3源都是在K~17.5 MAG的近红外调查中确定的。在中红外探测中，近红外/中红外通量比可以有效地用于区分恒星和星系。在我们的勘测区探测到的恒星被用来为LW2和LW3过滤器中的ELAIS ISOCAM数据推导出新的准确校准。我们表明，近红外到中红外彩色图可用于进一步对星系进行分类，以及研究恒星的形成。ELAIS的ISOCAM调查发现，它主要是为了探测强烈的恒星形成晚类型星系，可能是恒星爆发驱动的星系，它还发现了被遮挡的活动星系核。ELAIS星系产生的平均中红外通量比LW2/LW3=0.67+/-0.27。本文利用ISO和IRAS资料讨论了Fnu(6.7微米)/Fnu(15微米)比值作为恒星形成示踪剂的可行性。我们发现Fnu(2.2微米)/Fnu(15微米)比值也是星系活动水平的一个很好的指示器，并得出结论，在强恒星形成星系中，Fnu(6.7微米)/Fnu(15微米)比值的下降是15微米发射增加和6.7微米辐射明显耗尽的结果。近红外和中红外数据一起使估计星系中星际物质的相对数量成为可能。
We present J- and K-band near-infrared (near-IR) photometry of a sample of mid-infrared (mid-IR) sources detected by the Infrared Space Observatory (ISO) as part of the European Large Area ISO Survey (ELAIS) and study their classification and star-forming properties. We have used the Preliminary ELAIS Catalogue for the 6.7-mum (LW2) and 15-mum (LW3) fluxes. All of the high-reliability LW2 sources and 80 per cent of the LW3 sources are identified in the near-IR survey reaching K~ 17.5 mag. The near-IR/mid-IR flux ratios can effectively be used to separate stars from galaxies in mid-IR surveys. The stars detected in our survey region are used to derive a new accurate calibration for the ELAIS ISOCAM data in both the LW2 and LW3 filters. We show that near- to mid-IR colour-colour diagrams can be used to classify galaxies further, as well as to study star formation. The ELAIS ISOCAM survey is found mostly to detect strongly star-forming late-type galaxies, possibly starburst-powered galaxies, and it also picks out obscured active galactic nuclei. The ELAIS galaxies yield an average mid-IR flux ratio LW2/LW3 = 0.67 +/- 0.27. We discuss the fnu(6.7 mu m)/fnu(15 mu m) ratio as a star formation tracer using ISO and IRAS data of a local comparison sample. We find that the fnu(2.2 mu m)/fnu(15 mu m) ratio is also a good indicator of activity level in galaxies and conclude that the drop in the fnu(6.7 mu m)/fnu(15 mu m) ratio seen in strongly star-forming galaxies is a result of both an increase of 15-mum emission and an apparent depletion of 6.7-mum emission. Near-IR together with the mid-IR data make it possible to estimate the relative amount of interstellar matter in the galaxies.