The merger history of massive spheroids since z ~ 1 is size-independent

Abstract

Using a compilation of 379 massive (stellar mass M≥ 1011M⊙) spheroid-like galaxies fromthe near-infrared Palomar/DEEP-2 survey, we investigated, up to z ~ 1, whether the presenceof companions depends on the size of the host galaxy. We explored the presence of companionsfor mass ratios with respect to the central massive galaxy down to 1: 10 and 1: 100, andwithin projected distances of 30, 50 and 100 kpc of these objects. We found evidence that thesecompanions are equally distributed around both compact and extended massive spheroid-likegalaxies. This suggests that, at least since z ~ 1, the merger activity in these objects is nearlyhomogeneous across the whole population and that the merger history is not affected by the sizeof the host galaxy. Our results could indicate that compact and extended massive spheroid-likegalaxies are increasing in size at the same rate. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.