Use of Cross-Correlation Function to Study Formation Mechanism of Massive Elliptical Galaxies

Abstract

AbstractSpatial clustering nature of galaxies has been studied previously through auto correlation function. The same type of cross-correlation function has been used in the present work to investigate parametric clustering nature of galaxies with respect to masses and sizes of galaxies. Here, formation and evolution of several components of nearby massive early type galaxies (M*≥ 1.3 × 1011M⊙have been envisaged through cross-correlations, in the mass-size parametric plane, with high redshift (0.2 ⩽z⩽ 7) ETGs. It is found that the inner most components of nearby ETGs have significant correlation (~ 0.5 ± (0.02–0.07)) with ETGs in the highest redshift range (2 ⩽z⩽ 7) called ‘red nuggets’ whereas intermediate components are highly correlated (~ 0.65 ± (0.03–0.07)) with ETGs in the redshift range 0.5 ⩽z⩽ 0.75. The outermost part has no correlation in any range, suggesting a scenario throughin situaccretion. The above formation scenario is consistent with the previous results obtained for NGC5128 and to some extent for nearby elliptical galaxies after considering a sample of ETGs at high redshift with stellar masses greater than or equal to 108.73M⊙. So the present work indicates a three phase formation instead of two as discussed in previous works.