Towards large scale anisotropy studies

E.M. SANTOS; C. BONIFAZI; A. LETESSIER-SELVON

AUGER - GAP Notes

Pierre Auger Collaboration

Año: 2006 vol. 040

We have compared the usual UTC coverage with that obtained under the FAM hypothesis, using Monte Carlo simulation as well as the Auger SD data set. The FAM method was first applied on MC samples generated from a factorized acceptance in order to cross-check the algorithms and the power of the procedure. To estimate the size of the residual temperature effect over the local acceptance when the FAM coverage is used, we have simulated an isotropic cosmic ray distribution and a SD acceptance varying linearly with the temperature at the Auger site, taking into account the detector size variation as well. The final RA modulation observed in the excess map implies that such effect is of the order of 0.5% at most. By calculating the spherical harmonic coefficients a_lm, taking into account the detector exposure, we tested our ability to extract dipoles of moderate magnitudes on the sky in the presence of local temperature and detector size effects. Finally, the SD data collected during 2004 and 2005 was used to probe for modulations in different time scales (solar, sidereal and anti-sidereal time). A large scale multi-pole search for this data sample was also performed through calculation of the a_lm coefficients.