Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe K-Band Galaxy Luminosity Function
207
0
0.0
(
0
)
Authors
C.S. Kochanek
Ask ChatGPT about the research
No Arabic abstract
We measured the K-band luminosity function using a complete sample of 4192 morphologically-typed 2MASS galaxies with 7 < K < 11.25 mag spread over 2.12 str. Early-type (T < -0.5) and late-type (T > -0.5) galaxies have similarly shaped luminosity functions, alpha_e=-0.92+/-0.10 and alpha_l=-0.87+/-0.09. The early-type galaxies are brighter, M_*e=-23.53+/-0.06 mag compared to M_*l=-22.98pm0.06 mag, but less numerous, n_*e=(0.0045+/-0.0006)h^3/Mpc^3 compared to n_*l=(0.0101+/-0.0013)h^3/Mpc^3 for H_0=100h km/s Mpc, such that the late-type galaxies slightly dominate the K-band luminosity density, j_late/j_early=1.17+/-0.12. Our morphological classifications are internally consistent, consistent with previous classifications and lead to luminosity functions unaffected by the estimated uncertainties in the classifications. These luminosity functions accurately predict the K-band number counts and redshift distributions for K < 18 mag, beyond which the results depend on galaxy evolution and merger histories.
rate research
Read More
We present $K$-band luminosity functions for galaxies in a heterogeneous sample of 38 clusters at $0.1 < z < 1$. Using infrared-selected galaxy samples which generally reach 2 magnitudes fainter than the characteristic galaxy luminosity $L^*$, we fit Schechter functions to background-corrected cluster galaxy counts to determine $K^*$ as a function of redshift. Because of the magnitude limit of our data, the faint-end slope $alpha$ is fixed at -0.9 in the fitting process. We find that $K^*(z)$ departs from no-evolution predictions at $z > 0.4$, and is consistent with the behavior of a simple, passive luminosity evolution model in which galaxies form all their stars in a single burst at $z_f = 2 (3)$ in an $H_0 = 65 km/s Mpc^{-1}, Omega_M = 0.3, Omega_{Lambda}=0.7 (0)$ universe. This differs from the flat or negative infrared luminosity evolution which has been reported for high redshift field galaxy samples. We find that the observed evolution appears to be insensitive to cluster X-ray luminosity or optical richness, implying little variation in the evolutionary history of galaxies over the range of environmental densities spanned by our cluster sample. These results support and extend previous analyses based on the color evolution of high redshift cluster E/S0 galaxies, indicating not only that their stellar populations formed at high redshift, but that the assembly of the galaxies themselves was largely complete by $z approx 1$, and that subsequent evolution down to the present epoch was primarily passive.
We study the evolution of two fundamental properties of galaxy clusters: the luminosity function (LF) and the scaling relations between the total galaxy number N (or luminosity) and cluster mass M. Using a sample of 27 clusters (0<z<0.9) with new near-IR observations and mass estimates derived from X-ray temperatures, in conjunction with data from the literature, we construct the largest sample for such studies to date. The evolution of the characteristic luminosity of the LF can be described by a passively evolving population formed in a single burst at z=1.5-2. Under the assumption that the mass-temperature relation evolves self-similarly, and after the passive evolution is accounted for, the N-M scaling shows no signs of evolution out to z=0.9. Our data provide direct constraints on halo occupation distribution models, and suggest that the way galaxies populate cluster-scale dark matter halos has not changed in the past 7 Gyr, in line with previous investigations.
We use more than 110500 galaxies from the 2dF galaxy redshift survey (2dFGRS) to estimate the b_J-band galaxy luminosity function at redshift z=0, taking account of evolution, the distribution of magnitude measurement errors and small corrections for incompletenessin the galaxy catalogue. Throughout the interval -16.5>M- 5log h>-22, the luminosity function is accurately described by a Schechter function with M* -5log h =-19.66+/-0.07, alpha=-1.21+/-0.03 and phistar=(1.61+/-0.08) 10^{-2} h^3/Mpc^3, giving an integrated luminosity density of rho_L=(1.82+/-0.17) 10^8 h L_sol/Mpc^3 (assuming an Omega_0=0.3, Lambda_0=0.7 cosmology). The quoted errors have contributions from the accuracy of the photometric zeropoint, large scale structure in the galaxy distribution and, importantly, from the uncertainty in the appropriate evolutionary corrections. Our luminosity function is in excellent agreement with, but has much smaller statistical errors than an estimate from the Sloan Digital Sky Survey (SDSS) data when the SDSS data are accurately translated to the b_J-band and the luminosity functions are normalized in the same way. We use the luminosity function, along with maps describing the redshift completeness of the current 2dFGRS catalogue, and its weak dependence on apparent magnitude, to define a complete description of the 2dFGRS selection function. Details and tests of the calibration of the 2dFGRS photometric parent catalogue are also presented.
We explore the near-infrared (NIR) $K$-band properties of galaxies within 93 galaxy clusters and groups using data from the 2MASS. We use X-ray properties of these clusters to pinpoint cluster centers and estimate cluster masses. By stacking all these systems, we study the shape of the cluster luminosity function and the galaxy distribution within the clusters. We find that the galaxy profile is well described by the NFW profile with a concentration parameter c~3, with no evidence for cluster mass dependence of the concentration. Using this sample, whose masses span the range from $3times10^{13}M_odot$ to $2times10^{15}M_odot$, we confirm the existence of a tight correlation between total galaxy NIR luminosity and cluster binding mass, which indicates that NIR light can serve as a cluster mass indicator. From the observed galaxy profile, together with cluster mass profile measurements from the literature, we find that the mlr is a weakly decreasing function of cluster radius, and that it increases with cluster mass. We also derive the mean number of galaxies within halos of a given mass. We find that the mean number scales as $Npropto M^{0.84pm0.04}$ for galaxies brighter than $M_K=-21$, indicating high mass clusters have fewer galaxies per unit mass than low mass clusters. Using published observations at high redshift, we show that higher redshift clusters have higher mean occupation number than nearby systems of the same mass. By comparing the luminosity function & radial distribution of galaxies in low mass and high mass clusters, we show that there is a marked decrease in the number density of galaxies fainter than $M_*$ as one moves to higher mass clusters; in addition, extremely luminous galaxies are more probable in high mass clusters.
We present the results of a new study of the K-band galaxy luminosity function (KLF) at redshifts z<3.75, based on a nested combination of the UltraVISTA, CANDELS and HUDF surveys. The large dynamic range in luminosity spanned by this new dataset (3-4 dex over the full redshift range) is sufficient to clearly demonstrate for the first time that the faint-end slope of the KLF at z>0.25 is relatively steep (-1.3<alpha<-1.5 for a single Schechter function), in good agreement with recent theoretical and phenomenological models. Moreover, based on our new dataset we find that a double Schechter function provides a significantly improved description of the KLF at z<2. At redshifts z>0.25 the evolution of the KLF is remarkably smooth, with little or no evolution evident at faint (M_K>-20.5) or bright magnitudes (M_K<-24.5). Instead, the KLF is seen to evolve rapidly at intermediate magnitudes, with the number density of galaxies at M_K~-23 dropping by a factor of ~5 over the redshift interval 0.25<z<3.75. Motivated by this, we explore a simple description of the evolving KLF based on a double Schechter function with fixed faint-end slopes (alpha_1=-0.5, alpha_2=-1.5) and a shared characteristic magnitude (M_K*). According to this parameterisation, the normalisation of the component which dominates the faint-end of the KLF remains approximately constant, with phi*_2 decreasing by only a factor of ~2 between z~0 and z~3.25. In contrast, the component which dominates the bright end of the KLF at low redshifts evolves dramatically, becoming essentially negligible by z~3. Finally, we note that within this parameterisation, the observed evolution of M_K* between z~0 and z~3.25 is entirely consistent with M_K* corresponding to a constant stellar mass of M*~5x10^10 Msun at all redshifts.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
