ISOCAM-CVF 5-12 Micron Spectroscopy of Ultraluminous Infrared Galaxies
ISOCAM-CVF 5-12 Micron Spectroscopy of Ultraluminous Infrared Galaxies
复制标题
超亮红外星系的 ISOCAM-CVF 5-12 微米光谱
DOI：
10.1086/320543
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Paris Steward Observatory University of Hawaii Californi University
中科院分区：
文献类型：
--
作者：
Q. D. Tran;D. Lutz;R. Genzel;D. Rigopoulou;H. Spoon;E. Sturm;M. Gerin;D. Hines;A. Moorwood;D. Sanders;N. Scoville;Y. Taniguchi;M. W. M. E. Ens;Paris Steward Observatory University of Hawaii Californi University
利用红外空间天文台（ISO）上的ISOCAM系统的圆可变滤光器（CVF）光谱模式，获得了16个超亮红外星系（ULIRGs）的低分辨率中红外光谱。我们的样本完成了以前的ISO光谱的超和超亮红外星系向更高的光度。组合样品覆盖~1012-1013.1 L的红外光度范围。为了区分活动星系核（AGN）和星暴活动，我们使用与活动星系核相关的MIR连续谱和与星暴相关的6.2，7.7，8.6和11.3 μm MIR发射带归因于芳香碳质物质。对于这里研究的大约一半的高光度ULIRGs，强芳香族发射带表明星暴占主导地位。其他光谱主要是由一个强大的活动星系核相关的连续弱叠加发射功能的不确定性。我们的样本包含一个不寻常的例子，IRAS F00183-7111，即使在MIR中也高度模糊的AGN。本文提出了一种改进的定量描述星星形成和活动星系核活动对超高速红外辐射相对贡献的方法。ULIRG光谱是由一个星暴和活动星系核光谱的叠加拟合的，这两个光谱可能在不同的水平上被遮蔽。在模型中，恒星暴增和活动星系核的遮蔽不同的是显着更成功的模型与一个单一的灭绝。以前的结果的基础上一个简单的线到连续测量的芳香族排放强度得到证实，进一步支持鲁棒性的芳香族排放功能作为诊断ULIRG电源。作为辐射热光度的主要来源，星暴在这个范围的低端占主导地位，活动星系核在这个范围的高端。在~1012.4- 1012.5L的辐射通量范围内发生了由大部分星暴向大部分活动星系核的转变，个别明亮星暴的辐射通量可达~ 1012.65L。
We present low-resolution mid-infrared (MIR) spectra of 16 ultraluminous infrared galaxies (ULIRGs) obtained with the circular variable filter (CVF) spectroscopy mode of ISOCAM on board the Infrared Space Observatory (ISO). Our sample completes previous ISO spectroscopy of ultra- and hyperluminous infrared galaxies toward higher luminosities. The combined samples cover an infrared luminosity range of ~1012-1013.1 L☉. To discriminate active galactic nucleus (AGN) and starburst activity, we use the AGN-related MIR continuum and the starburst-related 6.2, 7.7, 8.6, and 11.3 μm MIR emission bands attributed to aromatic carbonaceous material. For about half of the high-luminosity ULIRGs studied here, strong aromatic emission bands suggest starburst dominance. Other spectra are dominated by a strong AGN-related continuum with weak superposed emission features of uncertain nature. Our sample contains one unusual example, IRAS F00183-7111, of an AGN that is highly obscured even in the MIR. An improved method to characterize quantitatively the relative contribution of star formation and AGN activity to the MIR emission of ULIRGs is presented. The ULIRG spectra are fitted by a superposition of a starburst and an AGN spectrum, both of which may be obscured at different levels. Models in which starburst and AGN obscuration differ are significantly more successful than models with a single extinction. Previous results based on a simpler line-to-continuum measure of aromatic emission strength are confirmed, further supporting the robustness of the aromatic emission feature as a diagnostic of ULIRG power sources. As dominant sources of the bolometric luminosity, starbursts prevail at the lower end and AGNs at the higher end of this range. The transition between mostly starburst and mostly AGN powered occurs at ~1012.4-1012.5 L☉, and individual luminous starbursts are found up to ~1012.65 L☉.