Bibcode
López-Sanjuan, C.; Balcells, M.; Pérez-González, P. G.; Barro, G.; García-Dabó, C. E.; Gallego, J.; Zamorano, J.
Bibliographical reference
Astronomy and Astrophysics, Volume 501, Issue 2, 2009, pp.505-518
Advertised on:
7
2009
Journal
Citations
81
Refereed citations
73
Description
Aims: The importance of disc-disc major mergers in galaxy evolution
remains uncertain. We study the major merger fraction in a
SPITZER/IRAC-selected catalogue in the GOODS-S field up to z 1 for
luminosity- and mass-limited samples. Methods: We select
disc-disc merger remnants on the basis of morphological
asymmetries/distortions, and address three main sources of systematic
errors: (i) we explicitly apply morphological K-corrections; (ii) we
measure asymmetries in galaxies artificially redshifted to zd
= 1.0 to deal with loss of morphological information with redshift; and
(iii) we take into account the observational errors in z and A, which
tend to overestimate the merger fraction, though use of maximum
likelihood techniques. Results: We obtain morphological merger
fractions (f_m^mph) below 0.06 up to z 1. Parameterizing the merger
fraction evolution with redshift as f_m^mph(z) = f_m^mph(0) (1+z)^m, we
find that m = 1.8 ± 0.5 for MB ≤ -20 galaxies,
while m = 5.4 ± 0.4 for Mstar ≥ 1010
M&sun; galaxies. When we translate our merger fractions to
merger rates (Re_m^mph), their evolution, parameterized as Re_m^mph(z) =
Re_m^mph(0) (1+z)^n, is quite similar in both cases: n = 3.3 ±
0.8 for MB ≤ -20 galaxies, and n = 3.5 ± 0.4 for
Mstar ≥ 1010 M&sun; galaxies. Conclusions: Our results imply that only 8% of today's
Mstar ≥ 1010 M&sun; galaxies have
undergone a disc-disc major merger since z 1. In addition, 21% of
Mstar ≥ 1010 M&sun; galaxies at z 1
have undergone one of these mergers since z 1.5. This suggests that
disc-disc major mergers are not the dominant process in the evolution of
Mstar ≥ 1010 M&sun; galaxies since z
1, with only 0.2 disc-disc major mergers per galaxy, but may be an
important process at z > 1, with ˜1 merger per galaxy at 1 <
z < 3.