The significance of the integrated Sachs-Wolfe effect revisited

Abstract

We revisit the state of the integrated Sachs-Wolfe (ISW) effect measurements in light of newly available data and address criticisms about the measurements which have recently been raised. We update the data set previously assembled by Giannantonio et al. to include new data releases for both the cosmic microwave background (CMB) and the large-scale structure (LSS) of the Universe. We find that our updated results are consistent with previous measurements. By fitting a single template amplitude, we now obtain a combined significance of the ISW detection at the 4.4 sigma level, which fluctuates by 0.4 sigma when alternative data cuts and analysis assumptions are considered. We also make new tests for systematic contaminations of the data, focusing in particular on the issues raised by Sawangwit et al. Amongst them, we address the rotation test, which aims at checking for possible systematics by correlating pairs of randomly rotated maps. We find results consistent with the expected data covariance, no evidence for enhanced correlation on any preferred axis of rotation, and therefore no indication of any additional systematic contamination. We publicly release the results, the covariance matrix, and the sky maps used to obtain them.Comment: 19 pages, 10 figures. MNRAS in pres

Planck2013 results. XIX. The integrated Sachs-Wolfe effect

“…As was mentioned already, a strong point of our results is the excellent compatibility between the ISW amplitude estimates with respect to the expected value. While our estimation deviates by about 0.5σ from the expected value, the Giannantonio et al (2012) result exceeds it by about 1σ and Ho et al (2008) is higher by 2σ.…”

“…For instance, Ho et al (2008) and Giannantonio et al (2012) found 3.7σ and 4.4σ detections, respectively. Compatibility with the former is below 1σ, while there is more tension (about 1.5σ) with the latter.…”

“…which was fitted to the data with parameters m = 1.5, β = 2.3 and z 0 = 0.34, which are identical to those found by Giannantonio et al (2012). For the galactic bias we used the value b = 1.2, which was found by Giannantonio et al (2012) by fitting the ΛCDM prediction to the observed auto-correlation function of the galaxies, and we adopted the mask proposed by them.…”

“…For the galactic bias we used the value b = 1.2, which was found by Giannantonio et al (2012) by fitting the ΛCDM prediction to the observed auto-correlation function of the galaxies, and we adopted the mask proposed by them. et al (2008b) produced a sample 3 of 50 superclusters and 50 supervoids identified from the luminous red galaxies (LRGs) in the SDSS (sixth data release, DR6, Adelman-McCarthy et al 2008), which covers an area of 7500 deg 2 on the sky.…”

“…Based on these data, many works can be found in the literature where the authors aim at making, and subsequectly improving, the measurement of the ISW effect through correlations with tracer catalogues: 2MASS (an infrared catalogue out to low redshifts around 0.1, Afshordi et al 2004;Rassat et al 2007;Francis & Peacock 2010b;Dupé et al 2011), HEAO (an X-ray survey at low redshift, with the first positive claim of detection, Boughn & Crittenden 2004), Sloan Digital Sky Survey (SDSS, an optical survey at intermediate redshifts, Fosalba et al 2003;Scranton et al 2003;Fosalba & Gaztañaga 2004;Padmanabhan et al 2005;Cabré et al 2006;Giannantonio et al 2006;Granett et al 2009;Xia 2009;Bielby et al 2010;López-Corredoira et al 2010;Sawangwit et al 2010), the NRAO VLA Sky Survey (NVSS, a radio catalogue with high-redshift sources, Boughn & Crittenden 2005;Vielva et al 2006;Pietrobon et al 2006a;McEwen et al 2007;Raccanelli et al 2008;Hernández-Monteagudo 2010;Massardi et al 2010;Schiavon et al 2012), and combined measurements with multiple tracers (Nolta et al 2004;Ho et al 2008;Corasaniti et al 2005;Gaztañaga et al 2006;Giannantonio et al 2008Giannantonio et al , 2012. The significance of the ISW detections that can be found in the literature range between 0.9σ and 4.7σ.…”