The Observations of Redshift Evolution in Large Scale Environments ORELSE Survey : I. The Survey Design and First Results on Cl 0023 0423 at z = 0.84 and RX J1821.6 6827 at z = 0.82 - AstrophysicsReportar como inadecuado




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Abstract: We present the Observations of Redshift Evolution in Large Scale EnvironmentsORELSE survey, a systematic search for structure on scales greater than 10Mpc around 20 well-known clusters at 0.6 < z < 1.3. We describe the surveydesign, the cluster sample, and our extensive observational data covering atleast 25- around each target cluster. We use adaptively-smoothed red galaxydensity maps from our wide-field optical imaging to identify candidategroups-clusters and intermediate-density large scale filaments-walls in eachcluster field. Because photometric techniques can be highly uncertain, thecrucial component of this survey is the unprecedented amount of spectroscopiccoverage. We are using the wide-field, multi-object spectroscopic capabilitiesof the DEep Multi-Object Imaging Spectrograph to obtain 100-200+ confirmedcluster members in each field. Our survey has already discovered the Cl 1604supercluster at z = 0.9. Here, we present the results on two additionalclusters, Cl 0023+0423 at z = 0.84 and RX J1821.6+6827 at z = 0.82. Theoptically-selected Cl 0023+0423 is a four-way group-group merger withconstituent groups having velocity dispersions between 206-479 km-s. The galaxypopulation is dominated by blue, star-forming galaxies, with a substantialcontribution from recent starbursts. In contrast, the X-ray-selected RXJ1821.6+6827 is a largely-isolated, massive cluster with a measured velocitydispersion of 926 +- 77 km-s. The cluster exhibits a well defined red sequencewith a large quiescent galaxy population. The results from these two targets,along with preliminary findings on other ORELSE clusters, suggest that opticalselection may be more effective than X-ray surveys at detecting less-evolved,dynamically-active systems at these redshifts. Abridged



Autor: L.M. Lubin, R.R. Gal, B.C. Lemaux, D.D. Kocevski, G.K. Squires

Fuente: https://arxiv.org/







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