Journal Article

Satellites around massive galaxies since <i>z</i>∼ 2

E. Mármol-Queraltó, I. Trujillo, P. G. Pérez-González, J. Varela and G. Barro

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 422, issue 3, pages 2187-2194
Published in print May 2012 | ISSN: 0035-8711
Published online May 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20765.x
Satellites around massive galaxies since z∼ 2

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The accretion of minor satellites has been postulated as the most likely mechanism to explain the significant size evolution of massive galaxies over cosmic time. Using a sample of 629 massive (Mstar∼ 1011 M) galaxies from the near-infrared Palomar/DEEP-2 survey, we explore what fraction of these objects have satellites with 0.01 < Msat/Mcentral < 1 (1:100) up to z= 1 and what fraction have satellites with 0.1 < Msat/Mcentral < 1 (1:10) up to z= 2 within a projected radial distance of 100 kpc. We find that the fraction of massive galaxies with satellites, after background correction, remains basically constant and close to 30 per cent for satellites with a mass ratio down to 1:100 up to z= 1, and close to 15 per cent for satellites with a 1:10 mass ratio up to z= 2. The family of spheroid-like massive galaxies presents a 2–3 times larger fraction of objects with satellites than the group of disc-like massive galaxies. A crude estimation of the number of 1:3 mergers a massive spheroid-like galaxy has experienced since z∼ 2 is around 2. For a disc-like galaxy this number decreases to ∼1.

Keywords: galaxies: evolution; galaxies: formation; galaxies: high-redshift

Journal Article.  6695 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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