The integrated Sachs-Wolfe effect in the AvERA cosmology

TL;DR

This paper compares the integrated Sachs-Wolfe effect predictions of the AvERA cosmology with the standard Lambda-CDM model, finding significant differences in magnitude and sign that could help distinguish these models with future observations.

Contribution

It provides the first detailed comparison of the ISW effect in AvERA and Lambda-CDM cosmologies, highlighting potential observational signatures to differentiate them.

Findings

AvERA predicts a 1.93-5.29 times larger ISW effect than Lambda-CDM.

AvERA shows an opposite-sign ISW effect at redshifts 1.5-4.4.

Current observations cannot distinguish models due to large errors.

Abstract

The recent AvERA cosmological simulation of R\'acz et al. (2017) has a $\Lambda \mathrm{CDM}$-like expansion history and removes the tension between local and Planck (cosmic microwave background) Hubble constants. We contrast the AvERA prediction of the integrated Sachs--Wolfe (ISW) effect with that of $\Lambda \mathrm{CDM}$. The linear ISW effect is proportional to the derivative of the growth function, thus it is sensitive to small differences in the expansion histories of the respective models. We create simulated ISW maps tracing the path of light-rays through the Millennium XXL cosmological simulation, and perform theoretical calculations of the ISW power spectrum. AvERA predicts a significantly higher ISW effect than $\Lambda \mathrm{CDM}$, $A=1.93-5.29$ times larger depending on the $l$ index of the spherical power spectrum, which could be utilized to definitively differentiate the models. We also show that AvERA predicts an opposite-sign ISW effect in the redshift range $z \approx 1.5 - 4.4$, in clear contrast with $\Lambda \mathrm{CDM}$. Finally, we compare our ISW predictions with previous observations. While at present these cannot distinguish between the two models due to large error bars, and lack of internal consistency suggesting systematics, ISW probes from future surveys will tightly constrain the models.