اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Red-Sequence Luminosity Function in Galaxy Clusters since z~1
134
0
0.0
(
0
)
تأليف
David G. Gilbank
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We use a statistical sample of ~500 rich clusters taken from 72 square degrees of the Red-Sequence Cluster Survey (RCS-1) to study the evolution of ~30,000 red-sequence galaxies in clusters over the redshift range 0.35<z<0.95. We construct red-sequence luminosity functions (RSLFs) for a well-defined, homogeneously selected, richness limited sample. The RSLF at higher redshifts shows a deficit of faint red galaxies (to M_V=> -19.7) with their numbers increasing towards the present epoch. This is consistent with the `down-sizing` picture in which star-formation ended at earlier times for the most massive (luminous) galaxies and more recently for less massive (fainter) galaxies. We observe a richness dependence to the down-sizing effect in the sense that, at a given redshift, the drop-off of faint red galaxies is greater for poorer (less massive) clusters, suggesting that star-formation ended earlier for galaxies in more massive clusters. The decrease in faint red-sequence galaxies is accompanied by an increase in faint blue galaxies, implying that the process responsible for this evolution of faint galaxies is the termination of star-formation, possibly with little or no need for merging. At the bright end, we also see an increase in the number of blue galaxies with increasing redshift, suggesting that termination of star-formation in higher mass galaxies may also be an important formation mechanism for higher mass ellipticals. By comparing with a low-redshift Abell Cluster sample, we find that the down-sizing trend seen within RCS-1 has continued to the local universe.
قيم البحث
اقرأ أيضاً
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 measure the evolution of the luminous red galaxy (LRG) luminosity function in the redshift range 0.1<z<0.9 using samples of galaxies from the Sloan Digital Sky Survey as well as new spectroscopy of high-redshift massive red galaxies. Our high-reds
hift sample of galaxies is largest spectroscopic sample of massive red galaxies at z~0.9 collected to date and covers 7 square deg, minimizing the impact of large scale structure on our results. We find that the LRG population has evolved little beyond the passive fading of its stellar populations since z~0.9. Based on our luminosity function measurements and assuming a non-evolving Salpeter stellar initial mass function, we find that the most massive (L>3L*) red galaxies have grown by less than 50% (at 99% confidence), since z=0.9, in stark contrast to the factor of 2-4 growth observed in the L* red galaxy population over the same epoch. We also investigate the evolution of the average LRG spectrum since z~0.9 and find the high-redshift composite to be well-described as a passively evolving example of the composite galaxy observed at low-redshift. From spectral fits to the composite spectra, we find at most 5% of the stellar mass in massive red galaxies may have formed within 1Gyr of z=0.9. While L* red galaxies are clearly assembled at z<1, 3L* galaxies appear to be largely in place and evolve little beyond the passive evolution of their stellar populations over the last half of cosmic history.
We present results on the rest-frame $H$-band luminosity functions (LF) of red sequence galaxies in seven clusters at 1.0 < z < 1.3 from the Gemini Observations of Galaxies in Rich Early Environments Survey (GOGREEN). Using deep GMOS-z and IRAC $3.6
mu$m imaging, we identify red sequence galaxies and measure their LFs down to $M_{H} sim M_{H}^{*} + (2.0 - 3.0)$. By stacking the entire sample, we derive a shallow faint end slope of $ alpha sim -0.35^{+0.15}_{-0.15} $ and $ M_{H}^{*} sim -23.52^{+0.15}_{-0.17} $, suggesting that there is a deficit of faint red sequence galaxies in clusters at high redshift. By comparing the stacked red sequence LF of our sample with a sample of clusters at z~0.6, we find an evolution in the faint end of the red sequence over the ~2.6 Gyr between the two samples, with the mean faint end red sequence luminosity growing by more than a factor of two. The faint-to-luminous ratio of our sample ($0.78^{+0.19}_{-0.15}$) is consistent with the trend of decreasing ratio with increasing redshift as proposed in previous studies. A comparison with the field shows that the faint-to-luminous ratios in clusters are consistent with the field at z~1.15 and exhibit a stronger redshift dependence. Our results support the picture that the build up of the faint red sequence galaxies occurs gradually over time and suggest that faint cluster galaxies, similar to bright cluster galaxies, experience the quenching effect induced by environment already at z~1.15.
We investigate the origin of the color-magnitude relation (CMR) observed in cluster galaxies by using a combination of a cosmological N-body simulation of a cluster of galaxies and a semi-analytic model of galaxy formation. The departure of galaxies
in the bright end of the CMR with respect to the trend defined by less luminous galaxies could be explained by the influence of minor mergers.
We present the evolution of the color-magnitude distribution of galaxy clusters from z = 0.45 to z = 0.9 using a homogeneously selected sample of ~1000 clusters drawn from the Red-Sequence Cluster Survey (RCS). The red fraction of galaxies decreases
as a function of increasing redshift for all cluster-centric radii, consistent with the Butcher-Oemler effect, and suggesting that the cluster blue population may be identified with newly infalling galaxies. We also find that the red fraction at the core has a shallower evolution compared with that at the cluster outskirts. Detailed examination of the color distribution of blue galaxies suggests that they have colors consistent with normal spirals and may redden slightly with time. Galaxies of starburst spectral type contribute less than 5% of the increase in the blue population at high redshift, implying that the observed Butcher-Oemler effect is not caused by a unobscured starbursts, but is more consistent with a normal coeval field population.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
