High Resolution Mid-Infrared Imaging of Ultraluminous Infrared Galaxies
High Resolution Mid-Infrared Imaging of Ultraluminous Infrared Galaxies
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DOI：
10.1086/301233
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发表时间：
1999-11
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影响因子：
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通讯作者：
B. Soifer;G. Neugebauer;K. Matthews;E. Egami;E. Becklin;A. Weinberger;M. Ressler;M. Werner;A. Evans;A. Evans;N. Scoville;J. Surace;J. Condon
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作者：
B. Soifer;G. Neugebauer;K. Matthews;E. Egami;E. Becklin;A. Weinberger;M. Ressler;M. Werner;A. Evans;A. Evans;N. Scoville;J. Surace;J. Condon
报道了利用凯克望远镜在8 ~ 25 μm的中红外波段对超亮红外星系（ULIRGs）的观测结果，其分辨率接近衍射极限。我们发现了非常紧凑的结构，与空间尺度小于0.″3（直径），在六个观察到的七个ULIRGs。这些紧凑的源从这些星系中发射出30%到100%的中红外能量。我们已经利用紧凑的中红外结构作为诊断AGN或紧凑（100-300 pc）的星暴是在这些ULIRGs的主要电源。在Markarian 231中，12.5 μm源的直径上限为0.″13，这表明红外源的大小必须随着波长的增加而增加，这与活动星系核模型一致。在IRAS 05189-2524和IRAS 08572+3915中，有强有力的证据表明源的大小随波长的增加而增加。这表明加热的中心源，而不是一个扩展的光度源，符合光学分类为活动星系核。在其他星系中看到的紧凑的中红外源不能用来区分最终的光度源。如果这些ULIRGs是由紧凑的恒星爆发提供动力的，那么在中心几百秒差距内看到的星星形成速率远远超过在附近的恒星爆发星系中看到的全球速率，并且接近附近恒星爆发星系中单个星系团的表面亮度。
Observations of ultraluminous infrared galaxies (ULIRGs) with an achieved resolution approaching the diffraction limit in the mid-infrared from 8 to 25 μm using the Keck Telescopes are reported. We find extremely compact structures, with spatial scales of less than 0.″3 (diameter) in six of the seven ULIRGs observed. These compact sources emit between 30% and 100% of the mid-infrared energy from these galaxies. We have utilized the compact mid-infrared structures as a diagnostic of whether an AGN or a compact (100–300 pc) starburst is the primary power source in these ULIRGs. In Markarian 231, the upper limit on the diameter of the 12.5 μm source, 0.″13, shows that the size of the infrared source must increase with increasing wavelength, consistent with AGN models. In IRAS 05189-2524 and IRAS 08572+3915 there is strong evidence that the source size increases with increasing wavelength. This suggests heating by a central source rather than an extended luminosity source, consistent with the optical classification as an AGN. The compact mid-infrared sources seen in the other galaxies cannot be used to distinguish the ultimate luminosity source. If these ULIRGs are powered by compact starbursts, the star formation rates seen in the central few hundred parsecs far exceed the global rates seen in nearby starburst galaxies, and approach the surface brightness of individual clusters in nearby starburst galaxies.