Two phase formation of massive elliptical galaxies: study through cross-correlation including spatial effect

Abstract

Area of study is the formation mechanism of the present-day population of elliptical galaxies, in the context of hierarchical cosmological models accompanied by accretion and minor mergers. The present work investigates the formation and evolution of several components of the nearby massive early-type galaxies (ETGs) through cross-correlation function (CCF), using the spatial parameters right ascension (RA) and declination (DEC), and the intrinsic parameters mass (M * ) and size. According to the astrophysical terminology, here these variables, namely mass, size, RA and DEC are termed as parameters, whereas the unknown constants involved in the kernel function are called hyperparameters. Throughout this paper, the parameter size is used to represent the effective radius (R e ). Following Huang et al. (2013a), each nearby ETG is divided into three parts on the basis of its R e value. We study the CCF between each of these three components of nearby massive ETGs and the ETGs in the high redshift range, 0.5 < z ≤ 2.7. It is found that the innermost components of nearby ETGs are highly correlated with ETGs in the redshift range, 2 < z ≤ 2.7, known as 'red nuggets'. The intermediate and the outermost parts have moderate correlations with ETGs in the redshift range, 0.5 < z ≤ 0.75. The quantitative measures are highly consistent with the two phase formation scenario of nearby massive ETGs, as suggested by various authors, and resolve the conflict raised in a previous work (De, Chattopadhyay, & Chattopadhyay 2014) suggesting other possibilities for the formation of Soumita Modak

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“…De et al, 2014;Modak et al, 2017). Here, data are collected from different sources and therefore needed to be checked for compatibility before pooling them together for further study.…”