Details

Autor(en) / Beteiligte

• López-Sanjuan, C.
• Balcells, M.
• Pérez-González, P. G.
• Barro, G.
• García-Dabó, C. E.
• Gallego, J.
• Zamorano, J.

Titel

The galaxy major merger fraction to ${z}$ ~ 1

Ist Teil von

• Astronomy and astrophysics (Berlin), 2009-07, Vol.501 (2), p.505-518

Ort / Verlag

EDP Sciences

Erscheinungsjahr

2009

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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 $(f_{\rm m}^{\rm mph})$ below 0.06 up to z ~ 1. Parameterizing the merger fraction evolution with redshift as $f_{\rm m}^{\rm mph}(z) = f_{\rm m}^{\rm mph}(0) (1+z)^m$, we find that m = 1.8 ± 0.5 for MB ≤ -20 galaxies, while m = 5.4 ± 0.4 for $M_{\star}$ ≥ 1010 $M_{\odot}$ galaxies. When we translate our merger fractions to merger rates $(\Re_{\rm m}^{\rm mph})$, their evolution, parameterized as $\Re_{\rm m}^{\rm mph}(z) = \Re_{\rm m}^{\rm mph}(0) (1+z)^n$, is quite similar in both cases: n = 3.3 ± 0.8 for MB ≤ -20 galaxies, and n = 3.5 ± 0.4 for $M_{\star} $ ≥ 1010 $M_{\odot}$ galaxies. Conclusions. Our results imply that only ~8% of today's $M_{\star}$ ≥ 1010 $M_{\odot}$ galaxies have undergone a disc-disc major merger since z ~ 1. In addition, ~21% of $M_{\star}$ $\geq $ 1010 $M_{\odot}$ 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 $M_{\star}$ ≥ 1010 $M_{\odot}$ galaxies since z ~ 1, with only 0.2 disc-disc major mergers per galaxy, but may be an important process at $z > 1$, with ${\sim}1$ merger per galaxy at 1 < z < 3.