Speaker
Prof.
Dominik Schwarz
(Bielefeld University)
Description
An important assumption of modern cosmology is that the CMB dipole is due to the proper motion of the solar system wrt the CMB. This fixes a reference frame for many observations, e.g. the Hubble diagram of SN1a. Planck observations of the largest multipole moments are consistent with the proper motion hypothesis, but also allow for sizeable non-kinetic contributions to the CMB dipole. The proper motion hypothesis can also be tested at any other wavelength, given good sky coverage and statistics are available. This is the case for modern radio point source catalogues. These allow us to measure the dipole distribution of radio sources at mean redshift of z ~ 1. The radio dipole can be measured at different radio frequencies and is compared to the CMB dipole. First results at three different frequency bands (at three different instruments) indicate an excess wrt to the expected signal based on the propor motion hypothesis only. The radio dipole directions are consistent with the CMB dipole direction at all three frequencies. Together with the alignment of low-l CMB multipole moments with the
CMB dipole, I argue that this is further evidence that the largest angular scales of the Universe are not properly understood so far.
| Overview or Regular Talk? | Regular: 45 min. |
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Primary author
Prof.
Dominik Schwarz
(Bielefeld University)
