Constraints on the merging channel of massive galaxies since z∼1



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Pérez González, Pablo Guillermo and Cava, A. and Cardiel López, Nicolás (2014) Constraints on the merging channel of massive galaxies since z∼1. Monthly notices of the Royal Astronomical Society, 444 (1). pp. 906-918. ISSN 0035-8711

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Official URL: 10.1093/mnras/stu1425


We probe the merging channel of massive galaxies over the z= 0.3 − 1.3 redshift window by studying close pairs in a sample of 238 galaxies with stellar mass >∼ 1011M⊙, from the SHARDS survey. SHARDS provides medium band photometry equivalent to low-resolution optical spectra (R∼50), allowing us to obtain extremely accurate photometric redshifts (median |∆z|/(1 + z) ∼ 0.55%) and to improve the constraints on the age distribution of the stellar populations. Our dataset is volume-limited, probing merger progenitors with mass ratios 1:100 (µ ≡ Msat/Mcen = 0.01) out to z=1.3. A strong correlation is found between the age difference of host and companion galaxy and stellar mass ratio, from negligible age differences in major mergers to age differences ∼4 Gyr for 1:100 minor mergers. However, this correlation is simply a reflection of the mass-age trend in the general population. The dominant contributor to the growth of massive galaxies corresponds to mass ratios µ >∼ 0.3, followed by a decrease in the fractional mass growth rate linearly proportional to log µ, at least down to µ ∼ 0.01, suggesting a decreasing role of mergers involving lowmass companions, especially if dynamical friction timescales are taken into account. A simple model results in an upper limit for the average mass growth rate of massive galaxies of (∆M/M)/∆t ∼ 0.08 ± 0.02 Gyr−1 , over the z ∼ 0.3. The majority of the stellar mass contributed by mergers does not introduce significantly younger populations, in agreement with the small radial age gradients observed in present-day early-type galaxies.

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© 2014 RAS.
We thank Carlos López-Sanjuan for his very valuable comments and suggestions. SHARDS is currently funded by the Spanish MICINN/MINECO with grant AYA2012-31277. Based on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC), in the island of La Palma. The authors acknowledge the use of the UCL Legion High Performance Computing Facility (Legion@UCL), and associated support services, in the completion of this work. IF acknowledges support from the IAC to carry out this research project. EMQ acknowledges the support of the European Research Council via the award of a Consolidator Grant (PI McLure). AH-C acknowledges support from the Augusto González Linares programme (Universidad de Cantabria), and the Spanish “Plan Nacional” grant AYA2012- 31447. This work has been supported by the ‘Programa Nacional de Astronomía y Astrofísica’ of the Spanish Ministry of Science and Innovation under grant AYA2010-21322-C03-02. We have made extensive use of the Rainbow Cosmological Surveys Database, operated by the Universidad Complutense de Madrid (UCM), in partnership with the University of California Observatories at Santa Cruz (UCO/Lick, UCSC).

Uncontrolled Keywords:Galaxies: evolution; Galaxies: formation; Galaxies: interactions; Galaxies: high; Redshift
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:29281
Deposited On:23 Mar 2015 08:56
Last Modified:10 Dec 2018 15:05

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