Satellites around massive galaxies since z∼ 2

Authors

  • E. Mármol-Queraltó,

    Corresponding author
    1. Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205, La Laguna, Tenerife, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205, La Laguna, Tenerife, Spain
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  • I. Trujillo,

    1. Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205, La Laguna, Tenerife, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205, La Laguna, Tenerife, Spain
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  • P. G. Pérez-González,

    1. Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, E-28040, Spain
    2. Steward Observatory, The University of Arizona 933 N Cherry Avenue, Tucson, AZ 85721, USA
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  • J. Varela,

    1. Instituto de Astrofísica de Canarias, c/Vía Láctea s/n, E-38205, La Laguna, Tenerife, Spain
    2. Departamento de Astrofísica, Universidad de La Laguna, E-38205, La Laguna, Tenerife, Spain
    3. Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan, 1, Planta-2, E44001-Teruel, Spain
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  • G. Barro

    1. UCO/Lick Observatory, University of California, Santa Cruz, CA 95064, USA
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E-mail: emq@iac.es

ABSTRACT

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.

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