The Munich Near-Infrared Cluster Survey -- IV. Biases in the Completeness of Near-Infrared Imaging Data

We present the results of completeness simulations for the detection of point sources as well as redshifted elliptical and spiral galaxies in the K'-band images of the Munich Near-Infrared Cluster Survey (MUNICS). The main focus of this work is to quantify the selection effects introduced by threshold-based object detection algorithms used in deep imaging surveys. Therefore, we simulate objects obeying the well-known scaling relations between effective radius and central surface brightness, both for de Vaucouleurs and exponential profiles. The results of these simulations, while presented for the MUNICS project, are applicable in a much wider context to deep optical and near-infrared selected samples. We investigate the detection probability as well as the reliability for recovering the true total magnitude with Kron-like (adaptive) aperture photometry. The results are compared to the predictions of the visibility theory of Disney and Phillipps in terms of the detection rate and the lost-light fraction. Additionally, the effects attributable to seeing are explored. The results show a bias against detecting high-redshifted massive elliptical galaxies in comparison to disk galaxies with exponential profiles, and that the measurements of the total magnitudes for intrinsically bright elliptical galaxies are systematically too faint. Disk galaxies, in contrast, show no significant offset in the magnitude measurement of luminous objects. Finally we present an analytic formula to predict the completeness of point-sources using only basic image parameters.Comment: 13 pages, 11 figures, accepted for publication in MNRA

The Mass Function of Field Galaxies at 0.4 < z < 1.2 Derived From the MUNICS K-Selected Sample

We derive the number density evolution of massive field galaxies in the redshift range 0.4 < z < 1.2 using the K-band selected field galaxy sample from the Munich Near-IR Cluster Survey (MUNICS). We rely on spectroscopically calibrated photometric redshifts to determine distances and absolute magnitudes in the rest-frame K-band. To assign mass-to-light ratios, we use two different approaches. First, we use an approach which maximizes the stellar mass for any K-band luminosity at any redshift. We take the mass-to-light ratio of a Simple Stellar Population (SSP) which is as old as the universe at the galaxy's redshift as a likely upper limit. Second, we assign each galaxy a mass-to-light ratio by fitting the galaxy's colours against a grid of composite stellar population models and taking their M/L. We compute the number density of galaxies more massive than 2 x 10^10 h^-2 Msun, 5 x 10^10 h^-2 Msun, and 1 x 10^11 h^-2 Msun, finding that the integrated stellar mass function is roughly constant for the lowest mass limit and that it decreases with redshift by a factor of ~ 3 and by a factor of ~ 6 for the two higher mass limits, respectively. This finding is in qualitative agreement with models of hierarchical galaxy formation, which predict that the number density of ~ M* objects is fairly constant while it decreases faster for more massive systems over the redshift range our data probe.Comment: 6 pages, 2 figures, to appear in the proceedings of the ESO/USM Workshop "The Mass of Galaxies at Low and High Redshift", Venice (Italy), October 24-26, 200

The Munich Near-Infrared Cluster Survey (MUNICS) - Number density evolution of massive field galaxies to z ~ 1.2 as derived from the K-band selected survey

We derive the number density evolution of massive field galaxies in the redshift range 0.4 < z < 1.2 using the K-band selected field galaxy sample from the Munich Near-IR Cluster Survey (MUNICS). We rely on spectroscopically calibrated photometric redshifts to determine distances and absolute magnitudes in the rest-frame K-band. To assign mass-to-light ratios, we use an approach which maximizes the stellar mass for any K-band luminosity at any redshift. We take the mass-to-light ratio, M/L_K, of a Simple Stellar Population (SSP) which is as old as the universe at the galaxy's redshift as a likely upper limit. This is the most extreme case of pure luminosity evolution and in a more realistic model M/L_K will probably decrease faster with redshift due to increased star formation. We compute the number density of galaxies more massive than 2 10^10 h^-2 solar masses, 5 10^10 h^-2 solar masses, and 1 10^11 h^-2 solar masses, finding that the integrated stellar mass function is roughly constant for the lowest mass limit and that it decreases with redshift by a factor of roughly 3 and by a factor of roughly 6 for the two higher mass limits, respectively. This finding is in qualitative agreement with models of hierarchical galaxy formation, which predict that the number density of ~ M* objects is fairly constant while it decreases faster for more massive systems over the redshift range our data probe.Comment: 4 pages, 5 figures, accepted for publication in ApJ Letter

The Munich Near-Infrared Cluster Survey (MUNICS) -- II. The K-Band Luminosity Function of Field Galaxies to z ~ 1.2

(Abriged) We present a measurement of the evolution of the rest-frame K-band luminosity function to z ~ 1.2 using a sample of more than 5000 K-selected galaxies drawn from the MUNICS dataset. Distances and absolute K-band magnitudes are derived using photometric redshifts from spectral energy distribution fits to BVRIJK photometry. These are calibrated using >500 spectroscopic redshifts. We obtain redshift estimates having a rms scatter of 0.055 and no mean bias. We use Monte-Carlo simulations to investigate the influence of the errors in distance associated with photometric redshifts on our ability to reconstruct the shape of the luminosity function. Finally, we construct the rest-frame K-band LF in four redshift bins spanning 0.4<z<1.2 and compare our results to the local luminosity function. We discuss and apply two different estimators to derive likely values for the evolution of the number density, Phi*, and characteristic luminosity, M*, with redshift. While the first estimator relies on the value of the luminosity function binned in magnitude and redshift, the second estimator uses the individually measured {M,z} pairs alone. In both cases we obtain a mild decrease in number density by \~ 25% to z=1 accompanied by brightening of the galaxy population by 0.5 to 0.7 mag. These results are fully consistent with an analogous analysis using only the spectroscopic MUNICS sample. The total K-band luminosity density is found to scale as dlog(rho_L)/dz = 0.24. We discuss possible sources of systematic errors and their influence on our parameter estimates.Comment: Accepted for publication in Ap

Dark matter halo properties from galaxy-galaxy lensing

We present results for a galaxy-galaxy lensing study based on imaging data from the Canada-France-Hawaii Telescope Legacy Survey Wide. From a 12 million object multi-colour catalogue for 124 deg^2 of photometric data in the u*g'r'i'z' filters we compute photometric redshifts (with a scatter of \sigma_{\Delta z/(1+z)} = 0.033 and an outlier rate of \eta=2.0 per cent for i'<=22.5) and extract galaxy shapes down to i'=24.0. We select a sample of lenses and sources with 0.05 < z_d <= 1 and 0.05 < z_s <= 2. We fit three different galaxy halo profiles to the lensing signal, a singular isothermal sphere (SIS), a truncated isothermal sphere (BBS) and a universal density profile (NFW). We derive velocity dispersions by fitting an SIS out to 100 h^{-1} kpc to the excess surface mass density \Delta\Sigma and perform maximum likelihood analyses out to a maximum scale of 2 h^{-1} Mpc to obtain halo parameters and scaling relations. We find luminosity scaling relations of \sigma_{red} ~ L^{0.24+-0.03} for the red lens sample, \sigma_{blue} ~ L^{0.23+-0.03} for blue lenses and \sigma ~ L^{0.29+-0.02} for the combined lens sample with zeropoints of \sigma*_{red}=162+-2 km/s, \sigma*_{blue}=115+-3 km/s and \sigma*=135+-2 km/s at a chosen reference luminosity L*_{r'} = 1.6 \times 10^10 h^{-2} L_{r',sun}. The steeper slope for the combined sample is due to the different zeropoints of the blue and red lenses and the fact that blue lenses dominate at low luminosities and red lenses at high luminosities. The mean effective redshifts for the lens samples are =0.28 for red lenses, =0.35 for blue lenses and =0.34 for the combined lens sample.Comment: 62 pages, 55 figures, accepted for publication in MNRAS, abridged abstract, includes corrections from final proof. Our created catalogues (photometry, photometric redshifts and shears) are publicly available at http://www.usm.uni-muenchen.de/people/stella/GGL

Large-Scale Structure in the NIR-Selected MUNICS Survey

The Munich Near-IR Cluster Survey (MUNICS) is a wide-area, medium-deep, photometric survey selected in the K' band. The project's main scientific aims are the identification of galaxy clusters up to redshifts of unity and the selection of a large sample of field early-type galaxies up to z < 1.5 for evolutionary studies. We created a Large Scale Structure catalog, using a new structure finding technique specialized for photometric datasets, that we developed on the basis of a friends-of-friends algorithm. We tested the plausibility of the resulting galaxy group and cluster catalog with the help of Color-Magnitude Diagrams (CMD), as well as a likelihood- and Voronoi-approach.Comment: 4 pages, to appear in "The Evolution of Galaxies III. From Simple Approaches to Self-Consistent Models", proceedings of the 3rd EuroConference on the evolution of galaxies, held in Kiel, Germany, July 16-20, 200

The Munich Near-Infrared Cluster Survey (MUNICS) - V. The evolution of the rest-frame K-band and J-band galaxy luminosity functions to z ~ 0.7

We present spectroscopic follow-up observations of galaxies from the Munich Near-Infrared Cluster Survey (MUNICS). MUNICS is a wide-field medium-deep K'-band selected survey covering 1 square degree in the near-infrared K' and J pass-bands, and 0.35 square degrees in I, R, V, and - recently completed - B. The spectroscopic sample comprises observations of objects down to a limit of K' < 17.5 in five survey fields (0.17 square degrees in total), and a sparsely selected deeper sample (K' < 19.0) constructed in one of the survey patches (0.03 square degrees). Here we describe the selection procedure of objects for spectroscopic observations, the observations themselves, the data reduction, and the construction of the spectroscopic catalogue containing roughly 500 galaxies with secure redshifts. Furthermore we discuss global properties of the sample like its distribution in colour-redshift space, the accuracy of redshift determination, and the completeness function of the data. We derive the rest-frame K'-band luminosity function of galaxies at median redshifts of z = 0.2, z = 0.4, and z = 0.7. We find evidence for mild evolution of magnitudes (-0.70 mag) and number densities (35 per cent) to redshift one. Furthermore, we present the rest-frame J-band luminosity function of galaxies at these redshifts, the first determination of this quantity at higher redshifts, with a behaviour similar to the K-band luminosity function.Comment: 18 pages, 15 figures, accepted for publication in MNRAS; high-resolution versions of Figures 5c-d and 8a-d available on http://www.usm.uni-muenchen.de/people/feulner/munics5/munics5.htm