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Title: CHANDRA DEEP OBSERVATION OF XDCP J0044.0-2033, A MASSIVE GALAXY CLUSTER AT z > 1.5

We report the analysis of the Chandra observation of XDCP J0044.0-2033, a massive, distant (z = 1.579) galaxy cluster discovered in the XDCP survey. The total exposure time of 380 ks with Chandra ACIS-S provides the deepest X-ray observation currently achieved on a massive, high-redshift cluster. Extended emission from the intra cluster medium (ICM) is detected at a very high significance level (S/N ∼ 20) on a circular region with a 44'' radius, corresponding to R {sub ext} = 375 kpc at the cluster redshift. We perform an X-ray spectral fit of the ICM emission modeling the spectrum with a single-temperature thermal mekal model. Our analysis provides a global temperature kT=6.7{sub −0.9}{sup +1.3} keV, and a iron abundance Z{sub Fe}=0.41{sub −0.26}{sup +0.29}Z{sub Fe{sub ⊙}} (error bars correspond to 1σ). We fit the background-subtracted surface brightness profile with a single β-model out to 44'', finding a rather flat profile with no hints of a cool core. We derive the deprojected electron density profile and compute the ICM mass within the extraction radius R {sub ext} = 375 kpc to be M {sub ICM}(r < R {sub ext}) = (1.48 ± 0.20) × 10{sup 13} M {sub ☉}. Under the assumption of hydrostatic equilibrium and assumingmore » isothermality within R {sub ext}, the total mass is M{sub 2500}=1.23{sub −0.27}{sup +0.46}×10{sup 14} M{sub ⊙} for R{sub 2500}=240{sub −20}{sup +30} kpc. Extrapolating the profile at radii larger than the extraction radius R {sub ext} we find M{sub 500}=3.2{sub −0.6}{sup +0.9}×10{sup 14} M{sub ⊙} for R{sub 500}=562{sub −37}{sup +50} kpc. This analysis establishes the existence of virialized, massive galaxy clusters at redshift z ∼ 1.6, paving the way to the investigation of the progenitors of the most massive clusters today. Given its mass and the XDCP survey volume, XDCP J0044.0-2033 does not create significant tension with the WMAP-7 ΛCDM cosmology.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ; ;  [6] ;  [7] ;  [8] ;  [9] ;  [10]
  1. INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy)
  2. Department of Physics, University of California, Davis One Shields Avenue, Davis, CA 95616-8677 (United States)
  3. INAF-Osservatorio Astronomico di Roma (OAR), via Frascati 33, I-00040 Monte Porzio Catone (Italy)
  4. Istitut d'Astrophysique Spatiale, CNRS, Bat. 121, Université Paris-Sud, F-91405 Orsay (France)
  5. Harvard-Smithsonian Center for Astrophysics 60 Garden Street, Cambridge, MA 02138 (United States)
  6. Università degli Studi di Trieste, Dipartimento di Fisica, Via A.Valerio, 2 I-34127 Trieste (Italy)
  7. Max-Planck-Institut fr extraterrestrische Physik Giessenbachstr.1, D-85748 Garching (Germany)
  8. European Space Astronomy Centre (ESAC), European Space Agency, Apartado de Correos 78, E-28691 Villanueva de la Canada, Madrid (Spain)
  9. CEA Saclay, Service d'Astrophysique, LOrme des Merisiers, Bat. 709, F-91191 Gif-sur-Yvette Cedex (France)
  10. INAF-Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, I-34143 Trieste (Italy)
Publication Date:
OSTI Identifier:
22364453
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; COMPUTERIZED SIMULATION; COSMOLOGICAL CONSTANT; COSMOLOGY; ELECTRON DENSITY; EQUILIBRIUM; GALAXY CLUSTERS; IRON; KEV RANGE; MASS; RED SHIFT; UNIVERSE; X RADIATION; X-RAY GALAXIES