X-Ray Evidence of a Buried Active Galactic Nucleus in UGC 5101
X-Ray Evidence of a Buried Active Galactic Nucleus in UGC 5101
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DOI：
10.1086/379503
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发表时间：
2003-09
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影响因子：
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通讯作者：
M. Imanishi;Y. Terashima;N. Anabuki;T. Nakagawa
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文献类型：
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作者：
M. Imanishi;Y. Terashima;N. Anabuki;T. Nakagawa
根据对其他波段的观测，我们对超高亮度红外星系UGC5101进行了X射线观测，认为该星系包含一个被掩埋的活动星系核(AGN)。我们在大于3keV的能量范围内探测到一个被吸收的硬成分，以及在0.5-2keV能量范围内的软发射。软X射线成分，可能是由于一次适度尘埃遮挡的扩展星暴，具有吸收校正的0.5-2keV X射线光度lx(0.5-2keV)=1.2×1041ergs S-1。0.5-2keV的X射线-红外光度比比正常星暴的标准值低约5倍，这表明这种扩展的星暴不太可能在UGC5101中占据主导地位。被吸收的硬组分最有可能的来源是假定的埋藏的活动星系核。6.4keV的FeKα发射线具有中等的等效宽度(~400 eV)，表明该硬成分是来自活动星系核的直接发射，而不是散射成分。经吸收校正后的活动星系核的2-10keV X射线光度估计为1x(2-10keV)~5×1042ergs S-1。本征2-10keV X射线光度和2-10keV X射线与红外光度比都与具有类似红外光度的Seyfert 2星系Mr k 463的测量值相当。
We present X-ray observations of the ultraluminous infrared galaxy, UGC 5101, thought to contain a buried active galactic nucleus (AGN) based on observations in other wave bands. We detected an absorbed hard component at greater than 3 keV, as well as soft emission in the energy range 0.5-2 keV. The soft X-ray component, possibly due to a modestly dust-obscured extended starburst, has an absorption-corrected 0.5-2 keV X-ray luminosity of LX(0.5-2 keV) = 1.2 × 1041 ergs s-1. The 0.5-2 keV X-ray-to-infrared luminosity ratio is a factor of ~5 lower than typical values for a normal starburst, suggesting that this extended starburst is unlikely to be energetically dominant in UGC 5101. The most plausible origin of the absorbed hard component is the putative buried AGN. The 6.4 keV Fe Kα emission line has a modest equivalent width (~400 eV), suggesting that this hard component is direct emission from the AGN, rather than a scattered component. The absorption-corrected 2-10 keV X-ray luminosity of the buried AGN was estimated to be LX(2-10 keV) ~ 5 × 1042 ergs s-1. The intrinsic 2-10 keV X-ray luminosity and the 2-10 keV X-ray-to-infrared luminosity ratio are both comparable to values measured for Mrk 463, a Seyfert 2 galaxy of similar infrared luminosity.