Use of spatial cross correlation function to study formation mechanism
  of massive elliptical galaxies
  Spatial clustering nature of galaxies have been studied previously through
auto correlation function. The same type of cross correlation function has been
used to investigate parametric clustering nature of galaxies e.g. with respect
to masses and sizes of galaxies.
  Here formation and evolution of several components of nearby massive early
type galaxies have been envisaged through cross correlations, in the mass-size
parametric plane, with high redshift early type galaxies (hereafter ETG).It is
found that the inner most components of nearby ETGs have significant
correlation with ETGs in the highest redshift range called red nuggets whereas
intermediate components are highly correlated with ETGs in the redshift range
with z value greater than 0.5 and less than 0.75. The outer most part has no
correlation in any range, suggesting a scenario through in situ accretion. The
above formation scenario is consistent with the previous results obtained for
NGC5128 (Chattopadhyay et al. (2009), Chattopadhyay et al. (2013)) and to some
extent for nearby elliptical galaxies (Huang et al. (2013)) after considering a
sample of ETGs at high redshift with stellar masses greater than or equal to
108.73 M-Sun. So the present work indicates a three phase formation of massive
nearby elliptical galaxies instead of two as discussed in previous works.
