基于贝叶斯先验理论及积分均值法计算星系的测光红移  

Photometric Redshift Calculation of Galaxies Based on Bayes'Prior Theory and Integral Mean Method

作　　者：鲍玉英 罗晓璇 杨帆 何蛟龙 BAO Yu-ying;LUO Xiao-xuan;YANG Fan;HE Jiao-long(School of Mathematics and Big Data,Guizhou Education University,Guiyang,Guizhou,550018)

机构地区：[1]贵州师范学院数学与大数据学院,贵州贵阳550018

出　　处：《贵州师范学院学报》2023年第12期44-50,共7页Journal of Guizhou Education University

基　　金：上海市星系与宇宙学半解析研究重点实验室开放课题“红移z~1.8-2.3的LBGs的研究”(SKLA2101);贵州师范学院校级博士项目“E-CDFS天区的红移z=1~3 Lyman break星系形态的研究”(2021037)。

摘　　要：星系的红移是一个非常重要的物理量,与星系的年龄、距离等有关。目前,对星系红移的估计大多是根据多波段的观测流量进行能谱拟合计算所得。选取扩展的钱德拉南天区E-CDFS为研究天区,采用MUSYC巡天的32个波段的观测数据,利用能谱拟合软件EAZY及其9个模板能谱线对其星表里的84402个源进行能谱拟合。在运行EAZY软件计算星系的红移时,考虑到了贝叶斯先验理论,即采用了星系的红光波段亮度概率分布来计算星系的红移zpeak,并与未采用贝叶斯先验计算得到的红移z_a进行了比较。得到的结论是,采用贝叶斯先验理论得到的红移与没有采用得到红移的标准偏差为0.013,而对于某些星系的红移,两种方法拟合得到的值偏差较大的原因是由于能谱拟合时不能区分巴尔莫跌落Balmer break和莱曼跌落Lyman break。The redshift of galaxies is a crucial physical quantity related to the age and distance of galaxies.Currently,the estimation of galaxy redshift is mostly based on spectral energy distribution(SED)fitting calculations using observations from multiple bands.In this study,the extended Chandra Deep Field South(E-CDFS)was selected as the research field,and the observational data from 32 bands of the Multiwavelength Survey by Yale-Chile(MUSYC)were utilized.The EAZY SED fitting software and its nine template spectra were employed to fit the SED of 84402 sources in the catalog.When calculating the redshift of galaxies using the EAZY software,Bayes’prior theory was taken into account,specifically using the probability distribution of the red-band brightness of galaxies to calculate the redshift(zpeak).The results were compared with the redshift(z_a)obtained without using Bayes’priors.The conclusion drawn is that the standard deviation of redshift obtained using Bayes'prior theory is 0.013 compared to the case without its use.For certain galaxies,the significant deviation in the fitted values between the two methods is attributed to the inability to distinguish between the Balmer break and Lyman break during spectral fitting.

关 键 词：贝叶斯公式 星系 红移 

分 类 号：P159.3[天文地球—天文学]