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

TL;DR

This study investigates the formation of massive elliptical galaxies using cross-correlation methods across spatial and redshift data, supporting a two-phase formation model with improved spatial effect analysis.

Contribution

It introduces a novel cross-correlation approach including spatial effects to study galaxy formation, confirming the two-phase formation scenario for massive ellipticals.

Findings

Inner components correlate with high-redshift 'red nuggets'

Outer components relate to lower-redshift ETGs

Results support the two-phase formation model

Abstract

Formation mechanism of present day population of elliptical galaxies have been revisited in the context of hierarchical cosmological models accompanied by accretion and minor mergers through cross correlation function including spatial effect. The present work investigates the formation and evolution of several components of nearby massive early type galaxies (ETGs) through cross-correlation in the spatial coordinates, right ascension and declination (RA, DEC) and mass-size parameter space with high redshift $(0.5\leq z\leq2.7)$ ETGs. It is found that innermost components of nearby ETGs are highly correlated with ETGs in the redshift range $(2\leq z\leq2.7)$ known as 'red nuggets'. The intermediate and outermost parts have moderate correlations with ETGs in the redshift range $(0.5\leq z\leq0.75)$. The quantitative measures are highly consistent with the two phase formation scenario of massive nearby early type galaxies as suggested by various authors and resolves the conflict raised in a previous work suggesting other possibilities for the formation of outermost part of nearby massive ETGs. The improvement is expected to be due to inclusion of spatial effects in addition to other linear parameters.