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

© 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. The authors acknowledge the referee's comments, which led to improvements in this work. They also thank Carlos Hernández Monteagudo for his very useful advice. LADG acknowledges support from the 'Caja Rural de Teruel' to develop this research. AJC is a Ramón y Cajal Fellow of the Spanish Ministry of Economy and Competitiveness. This work was supported by the 'Programa Nacional de Astronomía y Astrofísica' of the Spanish Ministry of Economy and Competitiveness under grants AYA2012-30789, AYA2010-21322-C03-02, AYA2009-10368 and AYA2009-07723-E. This work made use of the Rainbow Cosmological Surveys Database, which is operated by the Universidad Complutense de Madrid (UCM).
Using a compilation of 379 massive (stellar mass M ≳ 10^11 M_⊙) spheroid-like galaxies from the near-infrared Palomar/DEEP-2 survey, we investigated, up to z ∼ 1, whether the presence of companions depends on the size of the host galaxy. We explored the presence of companions for mass ratios with respect to the central massive galaxy down to 1 : 10 and 1 : 100, and within projected distances of 30, 50 and 100 kpc of these objects. We found evidence that these companions are equally distributed around both compact and extended massive spheroid-like galaxies. This suggests that, at least since z ∼ 1, the merger activity in these objects is nearly homogeneous across the whole population and that the merger history is not affected by the size of the host galaxy. Our results could indicate that compact and extended massive spheroid-like galaxies are increasing in size at the same rate.
Ministerio de Economía y Competitividad (MINECO)
Caja Rural de Teruel
Programa Nacional de Astronomía y Astrofísica (PNAyA), España
Depto. de Física de la Tierra y Astrofísica
Fac. de Ciencias Físicas
TRUE
pub