Speaker
Description
The search for anisotropies in the arrival directions of cosmic rays of the highest energies is essential in the on-going effort to identify their sources. After more than 15 years of operation, the exposure of the Pierre Auger Observatory exceeds 100,000 km^2 sr yr and several important scientific findings regarding anisotropy studies on various angular scales have been reported.
In the large-scale regime, a dipolar modulation above an energy threshold of 8 EeV was discovered with a significance exceeding the 5\sigma confidence level. The dipole exhibits an amplitude of 6.6^{+1.2}_{-0.8}\% and its maximum points ~125^\circ away from the Galactic center, thus providing observational evidence for an extragalactic origin of the highest-energy cosmic rays. The analysis of the equatorial component was extended to lower energies of ~0.03 EeV where the dipole phase changes towards the Galactic center. However, none of the lower-energy amplitudes is yet significant.
At the highest energies, searches for small- and intermediate-scale anisotropies were performed. A model-independent search for overdensities as well as a correlation study with the direction of the nearby radio galaxy Cen A was conducted. The latter analysis yields a one-sided post-trial significance of 3.9 \sigma for energies above 37 EeV on an angular scale of 28^\circ. Additionally, comparisons to four catalogs of candidate sources were performed using a maximum likelihood analysis. The comparison of the cosmic-ray arrival directions to a sample of starburst galaxies results in the highest post-trial significance, which lately surpassed the 4.5 \sigma confidence level above 38 EeV.
Details
Teresa Bister, RWTH Aachen University, Germany, https://www.institut3a.physik.rwth-aachen.de/cms/~jgoo/institut3a/
| Is this abstract from experiment? | Yes |
|---|---|
| Name of experiment and experimental site | The Pierre Auger Collaboration |
| Is the speaker for that presentation defined? | Yes |
