Aarhus University Seal / Aarhus Universitets segl

Astro talk - Shaun Hotchkiss: The (misbehaving) integrated Sachs Wolfe effect from "superstructures"

Info about event

Time

Thursday 18 April 2013,  at 14:15 - 15:00

Title: The (misbehaving) integrated Sachs Wolfe effect from "superstructures"

Speaker: Shaun Hotchkiss, Helsinki Institute of Physics, University of Helsinki, Finland

Abstract:
In LCDM, the gravitational potential in the universe decays at late times. This occurs because of the extra expansion caused by "dark energy". This decaying gravitational potential will cause a net blue/red shift on any photon traversing an over/under dense region. 

This is known as the integrated Sachs Wolfe (ISW) effect and should be detectable in the CMB. I will discuss an attempt made to observe the ISW effect of the most extreme over/under dense regions in the universe. The result, while statistically significant, is much larger than expectations from the standard LCDM model. It also appears to show up in more than one survey of the large scale structure of the universe and in both Planck and WMAP's CMB maps.