The extended ROSAT-ESO Flux-Limited X-ray Galaxy Cluster Survey (REFLEX II) V. Exploring a local underdensity in the Southern Sky

Abstract

Several claims have been made that we are located in a locally underdense region of the Universe based on observations of supernovae and galaxy density distributions. Two recent studies of K-band galaxy surveys have provided new support for a local underdensity in the galaxy distribution out to distances of 200 - 300 Mpc. If confirmed, such large local underdensities would have important implications on the interpretation of local measurements of cosmological parameters. Galaxy clusters have been shown to be ideal probes to trace the large-scale structure of the Universe. In this paper we study the local density distribution in the southern sky with the X-ray detected galaxy clusters from the REFLEX II cluster survey. From the normalized comoving number density of clusters we find an average underdensity of ~30 - 40% in the redshift range out to z ~0.04 (~170 Mpc) in the southern extragalactic sky with a significance larger than 3.4sigma. On larger scales from 300 Mpc to over 1 Gpc the density distribution appears remarkably homogeneous. The local underdensity seems to be dominated by the South Galactic Cap region. A comparison of the cluster distribution with that of galaxies in the K-band from a recent study shows that galaxies and clusters trace each other very closely in density. In the South Galactic Cap region both surveys find a local underdensity in the redshift range z= 0 to 0.05 and no significant underdensity in the North Galactic Cap at southern latitudes. Our results to not support cosmological models that attempt to interpret the cosmic acceleration by a large local void, since the local underdensity we find is not isotropic and limited to a size significantly smaller than 300 Mpc radius.

arXiv commentsubmitted to Astronomy and Astrophysics, 8 pages, 9 figures

References in corpus (26)

• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• The High-Z Supernova Search: Measuring Cosmic Deceleration and Global Cur vature of the Universe Using Type Ia Supernovae
• Galaxy and Mass Assembly (GAMA): survey diagnostics and core data release
• Improved Distances to Type Ia Supernovae with Multicolor Light Curve Shapes: MLCS2k2
• Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)
• The ROSAT-ESO Flux Limited X-ray (REFLEX) Galaxy Cluster Survey. V. The cluster catalogue
• Planck 2013 results. XXIII. Isotropy and statistics of the CMB
• The Representative XMM-Newton Cluster Structure Survey (REXCESS) of an X-ray Luminosity Selected Galaxy Cluster Sample
• Search for TeV Gamma-ray Emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S
• A Local Void and the Accelerating Universe
• Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution
• A Local Hubble Bubble from SNe Ia?
• Streaming motions of galaxy clusters within 12000 km/s - V. The peculiar velocity field
• Cosmic variance and the measurement of the local Hubble parameter
• Is there Evidence for a Hubble bubble? The Nature of Type Ia Supernova Colors and Dust in External Galaxies
• The ROSAT-ESO Flux Limited X-ray (REFLEX) Galaxy Cluster Survey II: The Spatial Correlation Function
• The Hawaii K-Band Galaxy Survey. II. Bright K-band Imaging
• Observational Constraints on General Relativistic Energy Conditions, Cosmic Matter Density and Dark Energy from X-Ray Clusters of Galaxies and Type-Ia Supernovae
• Analyses of Type Ia Supernova Data in Cosmological Models with a Local Void
• The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II)\\ II. Construction and Properties of the Survey
• The Local Hole revealed by galaxy counts and redshifts
• The extended ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey (REFLEX II) III. Construction of the first flux-limited supercluster sample
• Non-Gaussian morphology on large scales: Minkowski functionals of the REFLEX cluster catalogue
• Characterising superclusters with the galaxy cluster distribution
• The ROSAT-ESO Flux-Limited X-Ray (REFLEX) Galaxy Cluster Survey VI: Constraints on the cosmic matter density from the KL power spectrum
• Constructing mock catalogues for the REFLEX II galaxy cluster sample

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• Local gravitational redshifts can bias cosmological measurements
• Constraints on neutrino masses from the study of the nearby large-scale structure and galaxy cluster counts
• The galaxy luminosity function and the Local Hole
• Local Hole revisited: evidence for bulk motions and self-consistent outflow
• The effects of peculiar velocities in SN Ia environments on the local $H_0$ measurement
• The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey III: The Perseus-Pisces supercluster and the Southern Great Wall as traced by X-ray luminous galaxy clusters