A. S. Maniyar — Page 2

arXiv2018

Can the CIB constrain the dark energy?

Galaxies are often used as tracers of the large scale structure (LSS) to measure the Integrated Sachs-Wolfe effect (ISW) by cross-correlating the galaxy survey maps with the Cosmic Microwave Background (CMB) map. We use the Cosmic Infrared Background (CIB) as a tracer of the LSS to perform a theoretical CIB-CMB cross-correlation to measure the ISW for different Planck HFI frequencies. We discuss the detectability of this ISW signal using a Signal-to-noise ratio analysis and find that the ISW detected this way can provide us with the highest SNR for a single tracer ranging from 5 to 6.7 (maximum being for 857 GHz) with the CIB and CMB maps extracted over the whole sky. A Fisher matrix analysis showed that this measurement of the ISW can improve the constraints on the cosmological parameters; especially the equation of state of the dark energy $w$ by $\sim 47\%$. Performing a more realistic analysis including the galactic dust residuals in the CIB maps over realistic sky fractions shows that the dust power spectra dominate over the CIB power spectra at $\ell < 100$ and ISW can't be detected with high SNR. We perform the cross-correlation on the existing CIB-CMB maps over $\sim 11\%$ of the sky in the southern hemisphere and find that the ISW is not detected with the existing CIB maps over such small sky fractions.

astro-ph.CO↗

arXiv2018

Constraining cosmology with the cosmic microwave and infrared backgrounds correlation

We explore the use of the cosmic infrared background as a tracer of the LSS for cross-correlating with the CMB and exploit the ISW. We use the improved linear CIB model of Maniyar et al (2018) and derive the theoretical CIBxISW cross-correlation for Planck HFI frequencies 217, 353, 545 and 857 GHz and IRAS 3000 GHz. We predict a positive cross-correlation between the CIB and CMB whose amplitude decreases rapidly at small scales. We perform a signal-to-noise ratio (SNR) analysis on this cross-correlation. In the ideal case of the cross-correlation obtained over 70% (40%) of the sky with no residual contaminants (e.g. galactic dust) in maps, the SNR ranges from 4.2-5.6 (3.2-4.3) with the highest for 857 GHz. A Fisher matrix analysis shows that an ISW signal detected with such high SNR on the 40% sky can improve the constraints on the cosmological parameters considerably; constraints on the equation of state of the dark energy are improved by 80%. We then perform a more realistic analysis with the effect of residual galactic dust contamination in CIB maps. We calculate the dust power spectra for several frequencies and sky fractions which dominate over CIB at lower multipoles we are interested in. Considering conservative 10% residual level of galactic dust in the CIB power spectra, we find that the SNR drops drastically making ISW detection difficult. To check the capability of current maps to detect ISW via this method, we measure the cross-correlation of the CIB and the CMB Planck maps on so called GASS field covering an area of 11% in the southern hemisphere. We find that with such a small sky fraction and dust residuals present in CIB maps, we do not detect ISW signal and the measured signal is consistent with zero. In order not to degrade the SNR for the ISW measurement by more than 10% on the 40% sky, we find that the dust needs to be cleaned up to 0.01% level on the power spectrum.

astro-ph.CO↗