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تسجيل مستخدم جديدThe 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
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تأليف
N. Drory
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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 galaxys 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.
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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 dataset. Our data cover the stellar mass range 10^10 < M/Msun < 1
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(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.
The Munich Near-IR Cluster Survey (MUNICS) is a K selected survey covering 1 square degree in the K and J NIR bands with complementary optical photometry in the V, R, and I bands covering a subarea of 0.35 square degrees. The 3-sigma limiting magnitu
de is 19.5 in K. The main goals of the project are the identification of clusters of galaxies at redshifts 0.6<z<1.0 and the study of the evolution of the early-type field population at similar redshifts. Here we present first results regarding color distributions and the surface densities of EROs as well as photometric redshifts and a first clustering analysis of the 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 re
dshifts 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 galaxys redshift as a likely upper limit. Second, we assign each galaxy a mass-to-light ratio by fitting the galaxys 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.
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