Joint observation from Herschel and the South Pole Telescope
Date: 01 September 2013
Satellite: Herschel
Depicts: The Cosmic Microwave Background observed with SPT (left) and the Cosmic Infrared Background observed with Herschel (right)
Copyright: Image from G. Holder et al., 2013, The Astrophysical Journal Letters, 771, L16
This image shows data acquired on roughly the same field with the National Science Foundation's South Pole Telescope (SPT), in the left panel, and with ESA's Herschel Space Observatory, in the right panel. The field measures about 100 square degrees.
The SPT is a ground-based telescope, located in Antarctica, to observe the Cosmic Microwave Background (CMB) to very high angular resolution in a number of selected patches of the sky. The SPT image shows the CMB as observed at a frequency of 150 GHz.
With its wide spectral coverage ranging from far-infrared to sub-millimetre wavelengths, Herschel is sensitive to the Cosmic Infrared Background (CIB), which consists of the light emitted by stars and re-radiated by cosmic dust in all galaxies across cosmic history. In contrast to the CMB, which is the diffuse light that permeated the very early Universe, the CIB is a cumulative background, and arose with the formation of stars and galaxies.
The Herschel image is based on data collected with the SPIRE instrument at wavelengths of 250 microns (shown in blue), 350 microns (shown in green) and 500 microns (shown in red). Each dot in the image is a galaxy.
Gravitational lensing, the bending of light caused by massive objects, also affects the CMB as it propagates across the large-scale distribution of structure that started populating the Universe a few hundred million years after the Big Bang. Massive bodies, such as galaxies, galaxy clusters and the dark matter halos in which these are embedded, act as lenses and deflect the path of photons, causing distortions to the image of distant sources.
A team of cosmologists has combined the data from SPT and Herschel to achieve the first detection of a long-sought component in the Cosmic Microwave Background (CMB). This component, known as B-mode polarisation, is caused by gravitational lensing.
The data from Herschel contained information about the distribution of the galaxies that are distorting the CMB (and its polarised component) via gravitational lensing. As such, they provided extra leverage to make the detection of the B-modes induced by gravitational lensing on the CMB polarisation more robust.
