COSMOS场中z~0.3的超铝X射线源
Ultraluminous X-ray sources out to z~0.3 in the COSMOS field
摘要：
使用钱德拉观测，我们已经确定了一个样本的7个非核X射线源，在红移范围z=0.072-0.283，位于光学明亮的星系在宇宙巡天。利用COSMOS领域的多波长覆盖，我们研究了这些ULX的宿主星系的性质。详细地说，我们从H_alpha测量值和恒星质量出发，利用SED拟合技术计算了它们的恒星形成率，目的是根据宿主星系的性质计算它们有非核源的概率。我们划分的宿主星系在不同的形态类使用现有的ACS/HST成像。我们发现，我们的ULXs候选人位于SFR与M $_star$平面的区域，其中一个或多个非核可检测源是预期的。从形态学分析的ACS成像和使用的休息帧颜色，我们发现，我们的ULXs托管在晚型和早型星系。最后，我们发现，从L[0.5-2 keV]=3 x 10^39 erg s^-1到L[0.5 - 2 keV]= 2 x 10^40 erg s ^-1，拥有ULX的星系比例在~0.5%到~0.2%之间。
英文摘要：
Using Chandra observations we have identified a sample of seven off-nuclear X-ray sources, in the redshift range z=0.072-0.283, located within optically bright galaxies in the COSMOS Survey. Using the multi-wavelength coverage available in the COSMOS field, we study the properties of the host galaxies of these ULXs. In detail, we derived their star formation rate from H_alpha measurements and their stellar masses using SED fitting techniques with the aim to compute the probability to have an off-nuclear source based on the host galaxy properties. We divide the host galaxies in different morphological classes using the available ACS/HST imaging. We find that our ULXs candidates are located in regions of the SFR versus M$_star$ plane where one or more off-nuclear detectable sources are expected. From a morphological analysis of the ACS imaging and the use of rest-frame colours, we find that our ULXs are hosted both in late and early type galaxies. Finally, we find that the fraction of galaxies hosting a ULX ranges from ~0.5% to ~0.2% going from L[0.5-2 keV]=3 x 10^39 erg s^-1 to L[0.5-2 keV]= 2 x 10^40 erg s^-1.
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