The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform

Carlos S Frenk - One of the best experts on this subject based on the ideXlab platform.

  • a possible cold imprint of voids on the microwave background radiation
    The Astrophysical Journal, 2014
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat Filter scaled to the Radius of each void, we assess the statistical significance of the imprint at ~2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ~2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  • a possible cold imprint of voids on the microwave background radiation
    arXiv: Cosmology and Nongalactic Astrophysics, 2013
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0Filter scaled to the Radius of each void; we assess the statistical significance of the imprint at ~2$\sigma$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different Radius. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $\Lambda$CDM universe. The discrepancy is also at the ~2$\sigma$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

Yanchuan Cai - One of the best experts on this subject based on the ideXlab platform.

  • a possible cold imprint of voids on the microwave background radiation
    The Astrophysical Journal, 2014
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat Filter scaled to the Radius of each void, we assess the statistical significance of the imprint at ~2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ~2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  • a possible cold imprint of voids on the microwave background radiation
    arXiv: Cosmology and Nongalactic Astrophysics, 2013
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0Filter scaled to the Radius of each void; we assess the statistical significance of the imprint at ~2$\sigma$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different Radius. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $\Lambda$CDM universe. The discrepancy is also at the ~2$\sigma$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

Shaun Cole - One of the best experts on this subject based on the ideXlab platform.

  • a possible cold imprint of voids on the microwave background radiation
    The Astrophysical Journal, 2014
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat Filter scaled to the Radius of each void, we assess the statistical significance of the imprint at ~2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ~2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  • a possible cold imprint of voids on the microwave background radiation
    arXiv: Cosmology and Nongalactic Astrophysics, 2013
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0Filter scaled to the Radius of each void; we assess the statistical significance of the imprint at ~2$\sigma$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different Radius. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $\Lambda$CDM universe. The discrepancy is also at the ~2$\sigma$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

Istvan Szapudi - One of the best experts on this subject based on the ideXlab platform.

  • a possible cold imprint of voids on the microwave background radiation
    The Astrophysical Journal, 2014
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat Filter scaled to the Radius of each void, we assess the statistical significance of the imprint at ~2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ~2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  • a possible cold imprint of voids on the microwave background radiation
    arXiv: Cosmology and Nongalactic Astrophysics, 2013
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0Filter scaled to the Radius of each void; we assess the statistical significance of the imprint at ~2$\sigma$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different Radius. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $\Lambda$CDM universe. The discrepancy is also at the ~2$\sigma$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

Mark C Neyrinck - One of the best experts on this subject based on the ideXlab platform.

  • a possible cold imprint of voids on the microwave background radiation
    The Astrophysical Journal, 2014
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the Sloan Digital Sky Survey Data Release 7 spectroscopic redshift galaxy catalog, spanning redshifts 0 < z < 0.44. We find an imprint amplitude between 2.6 and 2.9 μK as viewed through a compensated top-hat Filter scaled to the Radius of each void, we assess the statistical significance of the imprint at ~2σ, and we make crucial use of N-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different radii. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal has a much higher amplitude than expected from ISW in the concordance ΛCDM universe. The discrepancy is also at the ~2σ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.

  • a possible cold imprint of voids on the microwave background radiation
    arXiv: Cosmology and Nongalactic Astrophysics, 2013
    Co-Authors: Yanchuan Cai, Mark C Neyrinck, Istvan Szapudi, Shaun Cole, Carlos S Frenk
    Abstract:

    We measure the average temperature decrement on the cosmic microwave background (CMB) produced by voids selected in the SDSS DR7 spectroscopic redshift galaxy catalog, spanning redshifts $0Filter scaled to the Radius of each void; we assess the statistical significance of the imprint at ~2$\sigma$. We make crucial use of $N$-body simulations to calibrate our analysis. As expected, we find that large voids produce cold spots on the CMB through the Integrated Sachs-Wolfe (ISW) effect. However, we also find that small voids in the halo density field produce hot spots, because they reside in contracting, larger-scale overdense regions. This is an important effect to consider when stacking CMB imprints from voids of different Radius. We have found that the same Filter Radius that gives the largest ISW signal in simulations also yields close to the largest detected signal in the observations. However, although it is low in significance, our measured signal is much higher-amplitude than expected from ISW in the concordance $\Lambda$CDM universe. The discrepancy is also at the ~2$\sigma$ level. We have demonstrated that our result is robust against the varying of thresholds over a wide range.