标题： 星系合并与明亮活动星系核的相关性 显示英文标题

标题： Correlation between Galaxy Mergers and Luminous AGN

摘要： 目前还不清楚是什么触发了活动星系核（AGN）的活动，但星系合并被认为是提供这种活动的主要机制之一。利用在不同地面望远镜拍摄的深光学图像，我们研究了在39个明亮的AGN（M$_{R}\, \lesssim$ -22.6 mag）中星系合并的比例，这些AGN的红移为$z \leq$ 0.3（中值红移为0.155），其宿主星系一般被认为是早期类型的星系。 通过对图像的目视检查，我们发现39个AGN宿主星系中有17个（43.6%）显示出当前或过去合并的证据，如潮汐尾、外壳和形态扰动。 为了查看这个比例是否异常高，我们还检查了斯隆数字巡天（SDSS）条带82数据中正常早期类型星系的合并比例（中值红移为0.04），其表面亮度极限与我们的成像数据相当。 为了纠正这两个样本红移差异的影响，我们在SDSS早期类型星系图像中放置一个明亮的点源作为人工AGN，并将其置于AGN的红移上进行了图像模拟。 在这个现实的模拟AGN样本中，合并比例仅为$\sim 5 - 15\%$ （为真实AGN的$1/4$ 到$1/8$）。 我们的结果强烈表明，明亮的AGN活动与星系合并有关。 显示英文摘要

摘要： It is not yet clear what triggers the activity of active galactic nuclei (AGNs), but galaxy merging has been suspected to be one of the main mechanisms fuelling the activity. Using deep optical images taken at various ground-based telescopes, we investigate the fraction of galaxy mergers in 39 luminous AGNs (M$_{R}\, \lesssim$ -22.6 mag) at $z \leq$ 0.3 (a median redshift of 0.155), of which the host galaxies are generally considered as early-type galaxies. Through visual inspection of the images, we find that 17 of 39 AGN host galaxies (43.6%) show the evidence for current or past mergers like tidal tails, shells, and disturbed morphology. In order to see if this fraction is abnormally high, we also examined the merging fraction of normal early-type galaxies in the Sloan Digital Sky Survey (SDSS) Strip 82 data (a median redshift of 0.04), of which the surface-brightness limit is comparable to our imaging data. To correct for the effects related to the redshift difference of the two samples, we performed an image simulation by putting a bright point source as an artificial AGN in the images of SDSS early-type galaxies and placing them onto the redshifts of AGNs. The merging fraction in this realistic sample of simulated AGNs is only $\sim 5 - 15\%$ ($1/4$ to $1/8$ of that of real AGNs). Our result strongly suggests that luminous AGN activity is associated with galaxy merging.