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RISS 인기검색어
- 검색키워드
- 저자 : Fiona Hoyle (검색결과 3 건)
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AN OBSERVATIONAL SIGNAL OF THE VOID SHAPE CORRELATION AND ITS LINK TO THE COSMIC WEB
Lee, Jounghun,Hoyle, Fiona IOP Publishing 2015 The Astrophysical journal Vol.803 No.1
<P>The shapes of cosmic voids are prone to distortions caused by external tidal forces since their low densities imply a lower internal resistance. This susceptibility of the void shapes to tidal distortions makes them useful as indicators of large-scale tidal and density fields, despite the practical difficulty in defining them. Using the void catalog constructed by Pan et al. from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS DR7), we detect a clear 4 sigma signal of spatial correlations of the void shapes on a scale of 20 h(-1) Mpc and show that the signal is robust against the projection of the void shapes onto the plane of sky. By constructing a simple analytic model for the void shape correlation, within the framework of tidal torque theory, we demonstrate that the void shape correlation function scales linearly with the two-point correlation function of the linear density field. We also find direct observational evidence for the cross-correlation of the void shapes with the large-scale velocity shear field that was linearly reconstructed by Lee et al. from SDSS DR7. We discuss the possibility of using the void shape correlation function to break the degeneracy between the density parameter and the power spectrum amplitude and to independently constrain the neutrino mass as well.</P>
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Cosmic voids in Sloan Digital Sky Survey Data Release 7
Pan, Danny C.,Vogeley, Michael S.,Hoyle, Fiona,Choi, Yun‐,Young,Park, Changbom Blackwell Publishing Ltd 2012 Monthly notices of the Royal Astronomical Society Vol.421 No.2
<P><B>ABSTRACT</B></P><P>We study the distribution of cosmic voids and void galaxies using Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Using the VoidFinder algorithm based on the original VoidFinder method devised by El‐Ad & Piran and implemented by Hoyle & Vogeley, we identify 1054 statistically significant voids in the Northern galactic hemisphere with radii > 10 <I>h</I><SUP>−1</SUP> Mpc. The filling factor of voids in the sample volume is 62 per cent. The largest void is just over 30 <I>h</I><SUP>−1</SUP> Mpc in effective radius. The median effective radius is 17 <I>h</I><SUP>−1</SUP> Mpc. The voids are found to be significantly underdense, with density contrast δ < − 0.85 at the edges of the voids. The radial‐density profiles of these voids are similar to predictions of dynamically distinct underdensities in gravitational theory. We find 8046 galaxies brighter than <I>M<SUB>r</SUB></I>=− 20.09 within the voids, accounting for 7 per cent of the galaxies. We compare the results of VoidFinder on SDSS DR7 to mock catalogues generated from a smoothed particle hydrodynamics (SPH) halo model simulation as well as other Λ cold dark matter (ΛCDM) simulations and find similar void fractions and void sizes in the data and simulations. This catalogue is made publicly available at http://www.physics.drexel.edu/~pan/VoidCatalog for download.</P>
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