Enhancements to the Southern Pierre Auger Observatory

The southern Pierre Auger Observatory has been detecting cosmic rays above 10¹⁸eV since 2004, exploiting a hybrid air shower detection technique, with 1660 water Cherenkov detectors together with 24 air fluorescence telescopes on a 3000 km² site. As low energy enhancements to the observatory, 3 additional telescopes with elevated fields of view were built (HEAT). The detector density was increased in the HEAT fields of view by a factor of four in an area of about 25 km². This setup enables unbiased hybrid data taking above 10¹⁷eV. The infilled area is also being equipped with large underground scintillator muon detectors (AMIGA). Finally, a prototype array of radio antenna stations (AERA), working from 30 to 80 MHz, has been installed in a part of the infill. Properties and status of AMIGA, HEAT, and AERA are presented.