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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 (fmmph) below 0.06 up to z ~ 1. Parameterizing the merger fraction evolution with redshift as fmmph(z) = fmmph(0) (1+z)m, we find that m = 1.8 ? 0.5 for MB? -20 galaxies, while m = 5.4 ? 0.4 for M*? 1010M?galaxies. When we translate our merger fractions to merger rates (Remmph), their evolution, parameterized as Remmph(z) = Remmph(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*? 1010M?galaxies.Conclusions. Our results imply that only ~8% of today's M*? 1010M?galaxies have undergone a disc-disc major merger since z ~ 1. In addition, ~21% of M*? 1010M?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*? 1010M?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.

Context. The galaxy number counts has been traditionally used to test models of galaxy evolution. However, the origin of significant differences in the shape of number counts at different wavelengths is still unclear. By relating the most remarkable features in the number counts with the underlying galaxy population it is possible to introduce further constraints on galaxy evolution.Aims. We aim to investigate the causes of the different shape of the K-band number counts when compared to other bands, analyzing in detail the presence of a change in the slope around K ?17.5.Methods. We present a near-infrared imaging survey, conducted at the 3.5?m telescope of the Calar Alto Spanish-German Astronomical Center?(CAHA), covering two separated fields centered on the HFDN and the Groth field, with a total combined area of ~0.27?deg2to a depth of K ?19 (3?, Vega). By combining our data with public deep K-band images in the CDFS (GOODS/ISAAC) and high quality imaging in multiple bands, we extract K-selected catalogs characterized with highly reliable photometric redshift estimates. We derive redshift binned number counts, comparing the results in our three fields to sample the effects of cosmic variance. We derive luminosity functions from the observed K-band in the redshift range [0.25?1.25], that are combined with data from the references in multiple bands and redshifts, to build up the K-band number count distribution.Results. The overall shape of the number counts can be grouped into three regimes: the classic Euclidean slope regime (d logN/dm ?0.6) at bright magnitudes; a transition regime at intermediate magnitudes, dominated by M*galaxies at the redshift that maximizes the product [Formula: see text]?*[Formula: see text]; and an ? dominated regime at faint magnitudes, where the slope asymptotically approaches ?0.4(?+1) controlled by post-M*galaxies. The slope of the K-band number counts presents an averaged decrement of ~50% in the range 15.5 < K < 18.5 (dlogN/dm?0.6?0.30). The rate of change in the slope is highly sensitive to cosmic variance effects. The decreasing trend is the consequence of a prominent decrease of the characteristic density ?*K,obs(~60% from z=0.5 to z=1.5) and an almost flat evolution of M*K,obs(1? compatible with M*K,obs=-22.89 ?0.25 in the same redshift range).

Context. Several studies have tried to ascertain whether the increase in abundance of the early-type galaxies (E-S0a's) with time is mainly due to major mergers, but have reached opposite conclusions.Aims. We have tested it directly through semi-analytical modelling, quantifying the possible contribution of the observed major mergers to the evolution of the high-mass end of the galaxy luminosity function (LF).Methods. The model analyses the backwards-in-time evolution of the massive early-type galaxies with log ($\mathcal{M}_*$/$\mathcal{M}_\ast$) >11 at z~ 0 (mETGs) under the hypothesis that each major merger leads to an early-type galaxy. The model considers only the major mergers strictly reported by observations at each redshift and assumes that gas-rich major mergers experience transitory phases as dust-reddened, star-forming galaxies (DSFs).Results. The model is able to reproduce the observed evolution of the galaxy LFs at z$\la$1 simultaneously for different rest-frame bands (B, I, and K) and for different selection criteria on colour and morphology. It also provides a framework in which apparently contradictory results on the recent evolution of the LF of massive red galaxies can be reconciled, just considering that observed samples of red galaxies can be significantly contaminated by DSFs. The model proves that it is feasible to build up ~50–60% of the present-day number density of mETGs at z$\la$1 through the coordinated action of wet, mixed, and dry major mergers, fulfilling global trends that are in general agreement with mass downsizing. The bulk of this assembly takes place during ~1 Gyr elapsed at 0.8

Context. Several studies have tried to ascertain whether the increase in abundance of the early-type galaxies (E-S0a's) with time is mainly due to major mergers, but have reached opposite conclusions.

Aims. Recent work has shown that major mergers of disc galaxies can only account for ~20% of the growth of the galaxy red sequence between z= 1 and z= 0. Our goal here is to provide merger frequencies that encompass both major and minor mergers, derived from close pair statistics. We aim to show that reliable close pair statistics can be derived from galaxy catalogues with mixed spectroscopic and photometric redshifts.Methods. We use B-band luminosity- and mass-limited samples from a Spitzer/IRAC-selected catalogue of GOODS-S. We present a new methodology for computing the number of close companions, $N_\mathrm{c}$, when spectroscopic redshift information is partial. The methodology extends the one used in spectroscopic surveys to make use of photometric redshift information. We select as close companions those galaxies separated by 6  h-1kpc

Aims. Recent work has shown that major mergers of disc galaxies can only account for ~20% of the growth of the galaxy red sequence between z= 1 and z= 0. Our goal here is to provide merger frequencies that encompass both major and minor mergers, derived from close pair statistics. We aim to show that reliable close pair statistics can be derived from galaxy catalogues with mixed spectroscopic and photometric redshifts.