We present a measurement of the evolution of the stellar mass function in four redshift bins at 0:4 < z <1:2, using a sample of more than 5000 K-selected galaxies drawn from the MUNICS (Munich Near-Infrared Cluster Survey) data set. Our data cover the stellar mass range 10 10 h À2 M M 10 12 h À2 M . We derive K-band mass-to-light ratios by fitting a grid of composite stellar population models of varying star formation history, age, and dust extinction to BVRIJK photometry. We discuss the evolution of the average mass-to-light ratio as a function of galaxy stellar mass in the K and B bands. We compare our stellar mass function at z > 0 to estimates obtained similarly at z ¼ 0. We find that the mass-to-light ratios in the K band decline with redshift. This decline is similar for all stellar masses above 10 10 h À2 M . Lower mass galaxies have lower mass-to-light ratios at all redshifts. The stellar mass function evolves significantly to z ¼ 1:2. The total normalization decreases by a factor of $2, the characteristic mass (the knee) shifts toward lower masses, and the bright end therefore steepens with redshift. The amount of number density evolution is a strong function of stellar mass, with more massive systems showing faster evolution than less massive systems. We discuss the total stellar mass density of the universe and compare our results to the values from the literature at both lower and higher redshifts. We find that the stellar mass density at z $ 1 is roughly 50% of the local value. Our results imply that the mass assembly of galaxies continues well after z $ 1. Our data favor a scenario in which the growth of the most massive galaxies is dominated by accretion and merging rather than star formation, which plays a larger role in the growth of less massive systems.

Abstract. We use the very deep and homogeneous I-band selected dataset of the FORS Deep Field (FDF) to trace the evolution of the luminosity function over the redshift range 0.5 < z < 5.0. We show that the FDF I-band selection down to I AB = 26.8 misses of the order of 10% of the galaxies that would be detected in a K-band selected survey with magnitude limit K AB = 26.3 (like FIRES). Photometric redshifts for 5558 galaxies are estimated based on the photometry in 9 filters (U, B, Gunn g, R, I, SDSS z, J, K and a special filter centered at 834 nm). A comparison with 362 spectroscopic redshifts shows that the achieved accuracy of the photometric redshifts is ∆z/(z spec + 1) ≤ 0.03 with only ∼1% outliers. This allows us to derive luminosity functions with a reliability similar to spectroscopic surveys. In addition, the luminosity functions can be traced to objects of lower luminosity which generally are not accessible to spectroscopy. We investigate the evolution of the luminosity functions evaluated in the restframe UV (1500 Å and 2800 Å), u , B, and g bands. Comparison with results from the literature shows the reliability of the derived luminosity functions. Out to redshifts of z ∼ 2.5 the data are consistent with a slope of the luminosity function approximately constant with redshift, at a value of −1.07 ± 0.04 in the UV (1500 Å, 2800 Å) as well as u , and −1.25 ± 0.03 in the blue (g , B). We do not see evidence for a very steep slope (α ≤ −1.6) in the UV at z ∼ 3.0 and z ∼ 4.0 favoured by other authors. There may be a tendency for the faint-end slope to become shallower with increasing redshift but the effect is marginal. We find a brightening of M * and a decrease of φ * with redshift for all analyzed wavelengths. The effect is systematic and much stronger than what can be expected to be caused by cosmic variance seen in the FDF. The evolution of M * and φ * from z = 0 to z = 5 is well described by the simple approximations Mfor M * and φ * . The evolution is very pronounced at shorter wavelengths (a = −2.19, and b = −1.76 for 1500 Å rest wavelength) and decreases systematically with increasing wavelength, but is also clearly visible at the longest wavelength investigated here (a = −1.08, and b = −1.29 for g ). Finally we show a comparison with semi-analytical galaxy formation models.Key words. galaxies: luminosity function, mass function -galaxy: fundamental parameters -galaxies: high-redshiftgalaxies: distances and redshifts -galaxies: evolution

We describe the survey design, calibration, commissioning, and emission-line detection algorithms for the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX). The goal of HETDEX is to measure the redshifts of over a million Lyα emitting galaxies between 1.88 < z < 3.52, in a 540 deg2 area encompassing a comoving volume of 10.9 Gpc3. No preselection of targets is involved; instead the HETDEX measurements are accomplished via a spectroscopic survey using a suite of wide-field integral field units distributed over the focal plane of the telescope. This survey measures the Hubble expansion parameter and angular diameter distance, with a final expected accuracy of better than 1%. We detail the project’s observational strategy, reduction pipeline, source detection, and catalog generation, and present initial results for science verification in the Cosmological Evolution Survey, Extended Groth Strip, and Great Observatories Origins Deep Survey North fields. We demonstrate that our data reach the required specifications in throughput, astrometric accuracy, flux limit, and object detection, with the end products being a catalog of emission-line sources, their object classifications, and flux-calibrated spectra.

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 σ ∆z/(1+z) = 0.033 and an outlier rate of η = 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 ∆Σ 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 σ red ∝ L 0.24±0.03 for the red lens sample, σ blue ∝ L 0.23±0.03 for blue lenses and σ ∝ L 0.29±0.02 for the combined lens sample with zeropoints of σ * red = 162 ± 2 km s −1 , σ * blue = 115 ± 3 km s −1 and σ * = 135 ± 2 km s −1 at a chosen reference luminosity L * r ′ = 1.6 × 10 10 h −2 L r ′ ,⊙ . 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 z red = 0.28 for red lenses, z blue = 0.35 for blue lenses and z = 0.34 for the combined lens sample. The BBS maximum likelihood analysis yields for the combined sample a velocity dispersion of σ * = 131 +2 −2 km s −1 and a truncation radius of s * = 184 +17 +14 h −1 kpc, corresponding to a total mass of M * total,BBS = 2.32 +0.28 −0.25 × 10 12 h −1 M ⊙ and a mass-to-light (M/L) ratio of M * total,BBS /L * = 178 +22 −19 h M ⊙ /L r ′ ,⊙ at L * r ′ . At a given luminosity, both velocity dispersion σ and truncation radius s are larger for red galaxies than for blue galaxies. For an NFW profile, we measure at L * r ′ a virial radius of r * 200 = 133 +3 −2 h −1 kpc and a concentration parameter of c * = 6.4 +0.9 −0.7 , implying a virial mass of M * 200 = 7.6 +0.5 −0.3 × 10 11 h −1 M ⊙ . At L * r ′ for blue galaxies the concentration parameter is slightly higher than for red galaxies and r 200 is significantly lower. For the combined sample, if described as a single power law, the M/L-ratio scales as M total,BBS /L ∝ L 0.12 +0.10 −0.11 , the concentration parameter scales as c ∝ L −0.07 +0.11 −0.11 . Analysing the M/L-scaling for red and blue galaxies separately, we find that a broken power law (with a flat slope at high luminosities) provides a more appropriate description for the red and possibly also for the blue galaxies. We measure M 200 /M star for red galaxies over 2.5 decades in stellar mass. We find a minimum for this ratio at M star ∼ 3 − 4 × 10 10 h −2 M ⊙ with a strong increase for lower stellar masses.