Open AccessCross‐correlation between WMAP and 2MASS: non‐Gaussianity induced by the SZ effect
Author(s) -
Cao Liang,
Chu YaoQuan,
Fang LiZhi
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10277.x
Subject(s) - cmb cold spot , physics , cosmic microwave background , astrophysics , galaxy , non gaussianity , galaxy cluster , cosmic background radiation , quantum mechanics , anisotropy
We study the non‐Gaussianity induced by the Sunyaev–Zel'dovich (SZ) effect in cosmic microwave background (CMB) fluctuation maps. If a CMB map is contaminated by the SZ effect of galaxies or galaxy clusters, the CMB maps should have similar non‐Gaussian features to the galaxy and cluster fields. Using the WMAP data and 2MASS galaxy catalogue, we show that the non‐Gaussianity of the 2MASS galaxies is imprinted on WMAP maps. The signature of non‐Gaussianity can be seen with the fourth‐order cross‐correlation between the wavelet variables of the WMAP maps and 2MASS clusters. The intensity of the fourth‐order non‐Gaussian features is found to be consistent with the contamination of the SZ effect of 2MASS galaxies. We also show that this non‐Gaussianity can not be seen by the high‐order autocorrelation of the WMAP . This is because the SZ signals in the autocorrelations of the WMAP data generally are weaker than the WMAP –2MASS cross‐correlations by a factor f 2 , which is the ratio between the powers of the SZ‐effect map and the CMB fluctuations on the scale considered. Therefore, the ratio of high‐order autocorrelations of CMB maps to cross‐correlations of the CMB maps and galaxy field would be effective to constrain the powers of the SZ effect on various scales.