Polarised radio emission associated with HESS J1912+101

The shell-type TeV source HESS J1912+101 was tentatively identified as an old supernova remnant, but is missing counterparts at radio and other frequencies. We analysed the Sino-German Urumqi λ6 cm survey and the Effelsberg λ11 cm and λ21 cm surveys to identify radio emission from HESS J1912+101 to clarify the question of a supernova origin. We find a partial shell of excessive polarisation at λ6 cm at the periphery of HESS J1912+101. At λ11 cm, its polarised emission is faint and suffers from depolarisation, while at λ21 cm, no related polarisation is seen. We could not separate the shell's total intensity signal from the confusing intense diffuse emission from the inner Galactic plane. However, a high percentage of polarisation in the shell's synchrotron emission is indicated. Our results support earlier suggestions that HESS J1912+101 is an old supernova remnant. The synchrotron emission is highly polarised, which is typical for evolved supernova remnants with low surface brightness. (paper)