LAMOST离群光谱J140242.45+092049.8特征分析

LAMOST巡天已获取超过100 000条星系光谱，为探索珍贵、稀有的天体从而完善现有科学理论提供了重要的数据条件。研究采用基于相关子空间的离群挖掘方法，从LAMOST DR3星系光谱数据中获得的离群数据挖掘结果中，针对呈现出多种稀有特征的光谱J140242.45+092049.8进行了深入分析。首先利用特征光谱线进行红移测量并交叉SDSS同源光谱提供的红移信息，测量并证认了该光谱的两套红移系统：吸收线系统z₁=0.020 95、发射线系统z₂=0.069 5。从整体上，通过交叉现有文献及SDSS图像特征，分析了该“吸收+发射”模式的双红移系统属于透镜星系的可能性，而红移间隔Δz=0.048远大于Keel指出的双星系具有物理关系的临界0.008，意味着该目标前景与背景星系之间只是视向重叠，即视向星系对，没有相互的物理作用；对于前景星系(吸收线系统)，通过测量光谱中呈现的特殊的特征线强度，分析了属于E+A星系的可能性；对于背景星系(发射线系统)光谱中呈现的双峰特征，分析了该光谱来自双峰发射线星系的可能性；此外，初步分析了该光谱中背景星系发射线强度关系异常的原因。

An Analysis of Outlier Spectrum:LAMOST J140242.45+092049.8

LAMOST regular survey has successfully observed more than 100,000 galaxy spectra,which provides important data for mining the precious and rare objects to improve the existing theories.In this paper,the s pectrum J140242.45+092049.8 is particularly chosen from LAMOST DR3 by using the outlier mining me thod based on the relevant subspaceand intensively discussed these rare characte ristics respectively.First of all,the dual-redshift system (absorption syst em:z1=0.020 95,emission system:z2=0.069 5) are measured and identified by fuzzilyrecognizing the characteristics lines and cross matching th e information of the homologous spectrum observed with SDSS.As a whole,the Δz=0.048,which is far greater than the physical interacting threshold (Δz<0.008) provided with Keel,indicating that they are superimposed in the l ight of sight rather than physical interacting occurring between the foreground galaxy and background one,and the possibility of lens for such "absorption+emi ss ion" mode dual-redshift spectrum is illuminated by studying the availableliter ature and analyzing the image feature provided with SDSS.For the foreground ga la xy (absorption system),the strong Balmer absorption lines and iron lines appea red simultaneouslyin the spectrumimplies that this object will be most likely be E+A galaxy.For the background galaxy (emission system),the characteristic of do uble peak emission lines is analyzed and the strange relationship between the em ission lines is also discussed in the end.