ISW in ΛCDM or something else?

Abstract

ABSTRACT We investigate a correlation between the Planck’s CMB temperature map and statistics based on the space density of quasars in the SDSS catalogue. It is shown that the amplitude of the positive correlation imposes a lower limit on the amplitude of the Integrated Sachs–Wolfe effect independent of the quasar bias factor. Implications of this constraint for the ISW effect in the Λ cold dark matter (ΛCDM) model are examined. Strength of the correlation indicates that the rms of temperature fluctuations associated with the quasars distributed between 1500 and 3000 Mpc likely exceeds $11{\!-\!}12\, \mu$K. The signal seems to be related to an overall space distribution of quasars rather than to a few exceptionally dominant structures like supervoids. Although, the present estimates are subject to sizable uncertainties, the signal apparently exceeds the model predictions of the ISW effect for the standard ΛCDM cosmology. This conclusion is consistent with several other investigations that also claim some disparity between the observed ISW signal and the theoretical predictions.