A Merged Catalog of Clusters of Galaxies From Early Sloan Digital Sky Survey Data (original) (raw)
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A Merged Catalog of Clusters of Galaxies from Early SDSS Data
2003
We present a catalog of 799 clusters of galaxies in the redshift range z_est = 0.05 - 0.3 selected from ~400 deg^2 of early SDSS commissioning data along the celestial equator. The catalog is based on merging two independent selection methods -- a color-magnitude red-sequence maxBCG technique (B), and a Hybrid Matched-Filter method (H). The BH catalog includes clusters with richness \Lambda >= 40 (Matched-Filter) and N_gal >= 13 (maxBCG), corresponding to typical velocity dispersion of \sigma_v >~ 400 km s^{-1} and mass (within 0.6 h^{-1) Mpc radius) >~ 5*10^{13} h^{-1} M_sun. This threshold is below Abell richness class 0 clusters. The average space density of these clusters is 2*10^{-5} h^3 Mpc^{-3}. All NORAS X-ray clusters and 53 of the 58 Abell clusters in the survey region are detected in the catalog; the 5 additional Abell clusters are detected below the BH catalog cuts. The cluster richness function is determined and found to exhibit a steeply decreasing cluster abundance with increasing richness. We derive observational scaling relations between cluster richness and observed cluster luminosity and cluster velocity dispersion; these scaling relations provide important physical calibrations for the clusters. The catalog can be used for studies of individual clusters, for comparisons with other sources such as X-ray clusters and AGNs, and, with proper correction for the relevant selection functions, also for statistical analyses of clusters.
Arxiv preprint arXiv: …, 2010
We study the properties of Brightest Cluster Galaxies (BCGs) drawn from a catalogue of more than 69000 clusters in the SDSS DR6 based on the adaptive matched filter technique (AMF, Szabo et al., 2010). Our sample consists of more than 14300 galaxies in the redshift range 0.1-0.3. We test the catalog by showing that it includes well-known BCGs which lie in the SDSS footprint. We characterize the BCGs in terms of r-band luminosities and optical colours as well as their trends with redshift. In particular, we define and study the fraction of blue BCGs, namely those that are likely to be missed by either colour-based cluster surveys and catalogues, as shown by a direct comparison to maxBCG clusters that are matched in the Szabo et al. catalogue. We further compare the properties of the BCGs to those of the second and third brightest galaxies in the same cluster. Finally, we morphologically classify those galaxies hosted in the richest clusters.
The Cluster Mass Function from Early Sloan Digital Sky Survey Data: Cosmological Implications
Astrophysical Journal, 2003
The mass function of clusters of galaxies is determined from 400 deg 2 of early commissioning imaging data of the Sloan Digital Sky Survey; ∼300 clusters in the redshift range z = 0.1 -0.2 are used. Clusters are selected using two independent selection methods: a Matched Filter and a red-sequence color magnitude technique. The two methods yield consistent results. The cluster mass function is compared with large-scale cosmological simulations. We find a best-fit cluster normalization relation of σ 8 Ω m 0.6 = 0.33 ± 0.03 (for 0.1 Ω m 0.4), or equivalently σ 8 = ( 0.16 Ωm ) 0.6 . The amplitude of this relation is significantly lower than the previous canonical value, implying that either Ω m is lower than previously expected (Ω m = 0.16 if σ 8 = 1) or σ 8 is lower than expected (σ 8 = 0.7 if Ω m = 0.3) -2as suggested by recent results. The shape of the cluster mass function partially breaks this classic degeneracy; we find best-fit parameters of Ω m = 0.19 ± 0.08 0.07 and σ 8 = 0.9 ± 0.3 0.2 . High values of Ω m ( 0.4) and low σ 8 ( 0.6) are excluded at 2σ.
The clustering of luminous red galaxies in the Sloan Digital Sky Survey imaging data
Monthly Notices of the Royal Astronomical Society, 2007
We present the 3D real space clustering power spectrum of a sample of ∼ 600, 000 luminous red galaxies (LRGs) measured by the Sloan Digital Sky Survey (SDSS), using photometric redshifts. These galaxies are old, elliptical systems with strong 4000Å breaks, and have accurate photometric redshifts with an average error of ∆z = 0.03. This sample of galaxies ranges from redshift z = 0.2 to 0.6 over 3, 528 deg 2 of the sky, probing a volume of 1.5h −3 Gpc 3 , making it the largest volume ever used for galaxy clustering measurements. We measure the angular clustering power spectrum in eight redshift slices and use well-calibrated redshift distributions to combine these into a high precision 3D real space power spectrum from k = 0.005hMpc −1 to k = 1hMpc −1 . We detect power on gigaparsec scales, beyond the turnover in the matter power spectrum, at a ∼ 2σ significance for k < 0.01hMpc −1 , increasing to 5.5σ for k < 0.02hMpc −1 . This detection of power is on scales significantly larger than those accessible to current spectroscopic redshift surveys. We also find evidence for baryonic oscillations, both in the power spectrum, as well as in fits to the baryon density, at a 2.5σ confidence level. The large volume and resulting small statistical errors on the power spectrum allow us to constrain both the amplitude and scale dependence of the galaxy bias in cosmological fits. The statistical power of these data to constrain cosmology is ∼ 1.7 times better than previous clustering analyses. Varying the matter density and baryon fraction, we find Ω M = 0.30 ± 0.03, and Ω b /Ω M = 0.18 ± 0.04, for a fixed Hubble constant of 70 km/s/Mpc and a scale-invariant spectrum of initial perturbations. The detection of baryonic oscillations also allows us to measure the comoving distance to z = 0.5; we find a best fit distance of 1.73 ± 0.12Gpc, corresponding to a 6.5% error on the distance. These results demonstrate the ability to make precise clustering measurements with photometric surveys. c 0000 RAS
Galaxy clusters in the SDSS Stripe 82 based on photometric redshifts
Astronomy & Astrophysics, 2015
Context. The discovery of new galaxy clusters is important for two reasons. First, clusters are interesting per se, since their detailed analysis allows us to understand how galaxies form and evolve in various environments and second, they play an important part in cosmology because their number as a function of redshift gives constraints on cosmological parameters. Aims. We have searched for galaxy clusters in the Stripe 82 region of the Sloan Digital Sky Survey, and analysed various properties of the cluster galaxies. Methods. Based on a recent photometric redshift (hereafter photo-z) galaxy catalogue, we built a cluster catalogue by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to fine-tune the AMACFI parameters and make the cluster detection as reliable as possible. The same method was applied to the Millennium simulation to estimate our detection efficiency and the approximate masses of the detected clusters. Considering all the cluster galaxies (i.e. within a 1 Mpc radius of the cluster to which they belong and with a photo-z differing by less than ±0.05 from that of the cluster), we stacked clusters in various redshift bins to derive colour-magnitude diagrams and galaxy luminosity functions (GLFs). For each galaxy brighter than M r < −19.0, we computed the disk and spheroid components by applying SExtractor, and by stacking clusters we determined how the disk-to-spheroid flux ratio varies with cluster redshift and mass. Results. We detected 3663 clusters in the redshift range 0.15 ≤ z ≤ 0.70, with estimated mean masses between ∼10 13 and a few 10 14 M. We cross-matched our catalogue of candidate clusters with various catalogues extracted from optical and/or X-ray data. The percentages of redetected clusters are at most 40% because in all cases we detect relatively massive clusters, while other authors detect less massive structures. By stacking the cluster galaxies in various redshift bins, we find a clear red sequence in the (g − r) versus r colour−magnitude diagrams, and the GLFs are typical of clusters, though with a possible contamination from field galaxies. The morphological analysis of the cluster galaxies shows that the fraction of late-type to early-type galaxies shows an increase with redshift (particularly in 9σ clusters) and a decrease with detection level, i.e. cluster mass. Conclusions. From the properties of the cluster galaxies, the majority of the candidate clusters detected here seem to be real clusters with typical cluster properties.
Galaxy clusters in the SDSS Stripe 82 based on galaxy photometric redshifts
2015
Context. The discovery of new galaxy clusters is important for two reasons. First, clusters are interesting per se, since their detailed analysis allows us to understand how galaxies form and evolve in various environments and second, they play an important part in cosmology because their number as a function of redshift gives constraints on cosmological parameters. Aims. We have searched for galaxy clusters in the Stripe 82 region of the Sloan Digital Sky Survey, and analysed various properties of the cluster galaxies. Methods. Based on a recent photometric redshift (hereafter photo−z) galaxy catalogue, we built a cluster catalogue by applying the Adami & MAzure Cluster FInder (AMACFI). Extensive tests were made to fine-tune the AMACFI parameters and make the cluster detection as reliable as possible. The same method was applied to the Millennium simulation to estimate our detection efficiency and the approximate masses of the detected clusters. Considering all the cluster galaxies (i.e. within a 1 Mpc radius of the cluster to which they belong and with a photo−z differing by less than ±0.05 from that of the cluster), we stacked clusters in various redshift bins to derive colour-magnitude diagrams and galaxy luminosity functions (GLFs). For each galaxy brighter than M r < −19.0, we computed the disk and spheroid components by applying SExtractor, and by stacking clusters we determined how the disk-to-spheroid flux ratio varies with cluster redshift and mass. Results. We detected 3663 clusters in the redshift range 0.15 ≤ z ≤ 0.70, with estimated mean masses between ∼ 10 13 and a few 10 14 M. We cross-matched our catalogue of candidate clusters with various catalogues extracted from optical and/or X-ray data. The percentages of redetected clusters are at most 40% because in all cases we detect relatively massive clusters, while other authors detect less massive structures. By stacking the cluster galaxies in various redshift bins, we find a clear red sequence in the (g − r) versus r colour-magnitude diagrams, and the GLFs are typical of clusters, though with a possible contamination from field galaxies. The morphological analysis of the cluster galaxies shows that the fraction of late-type to early-type galaxies shows an increase with redshift (particularly in 9σ clusters) and a decrease with detection level, i.e. cluster mass. Conclusions. From the properties of the cluster galaxies, the majority of the candidate clusters detected here seem to be real clusters with typical cluster properties.
We present a comparison of three cluster finding algorithms from imaging data using Monte Carlo simulations of clusters embedded in a 25 deg 2 region of Sloan Digital Sky Survey (SDSS) imaging data: the Matched Filter (MF;, the Adaptive Matched Filter (AMF; ) and a color-magnitude filtered Voronoi Tessellation Technique (VTT). Among the two matched filters, we find that the MF is more efficient in detecting faint clusters, whereas the AMF evaluates the redshifts and richnesses more accurately, therefore suggesting a hybrid method (HMF) that combines the two. The HMF outperforms the VTT when using a background that is uniform, but it is more sensitive to the presence of a non-uniform galaxy background than is the VTT; this is due to the assumption of a uniform background in the HMF model. We thus find that for the detection thresholds we determine to be appropriate for the SDSS data, the performance of both algorithms are similar; we present the selection function for each method evaluated with these thresholds as a function of redshift and richness. For simulated clusters generated with a Schechter luminosity function (M * r = −21.5 and α = −1.1) both algorithms are complete for Abell richness > ∼ 1 clusters up to z ∼ 0.4 for a sample magnitude limited to r = 21. While the cluster parameter evaluation shows a mild correlation with the local background density, the detection efficiency is not significantly affected by the background fluctuations, unlike previous shallower surveys.
Clustering of Luminous Red Galaxies in the Sloan Digital Sky Survey
2004
We present measurements and implications of the clustering of a large spectroscopic sample of luminous red galaxies from the Sloan Digital Sky Survey. The sample includes 55,000 galaxies over 3800 square degrees from redshift 0.16 to 0.47. We have measured the auto-correlation function on scales from 400 kpc to 200 Mpc, as well as the cross-correlation between the spectroscopic galaxies and 16 million galaxies from the SDSS imaging. On small scales, the sample reveals a strong pattern of luminosity and scale-dependent bias that is consistent with the galaxies residing in very massive halos. On large scales, the correlations probe the linear regime over a wide range of scales and are in excellent agreement with LCDM.
The 2dF Galaxy Redshift Survey: a targeted study of catalogued clusters of galaxies
Monthly Notices of the Royal Astronomical Society, 2002
We have carried out a study of known clusters within the 2dF Galaxy Redshift Survey (2dFGRS) observed areas and have identified 431 Abell, 173 APM and 343 EDCC clusters. Precise redshifts, velocity dispersions and new centroids have been measured for the majority of these objects, and this information has been used to study the completeness of these catalogues, the level of contamination from foreground and background structures along the cluster's line of sight, the space density of the clusters as a function of redshift, and their velocity dispersion distributions. We find that the Abell and EDCC catalogues are contaminated at the level of about 10%, whereas the APM catalogue suffers only 5% contamination. If we use the original catalog centroids, the level of contamination rises to approximately 15% for the Abell and EDCC catalogues, showing that the presence of foreground and background groups may alter the richness of clusters in these catalogues. There is a deficiency of clusters at z ∼ 0.05 that may correspond to a large underdensity in the Southern hemisphere. From the cumulative distribution of velocity dispersions for these clusters, we derive an upper limit to the space density of σ > 1000 km s −1 clusters of 3.6 × 10 −6 h 3 Mpc −3 . This result is used to constrain models for structure formation; our data favour low-density cosmologies, subject to the usual assumptions concerning the shape and normalization of the power spectrum.