Halo fraction in TeV-bright pulsar wind nebulae G. Giacinti, A. M. W. Mitchell, R. López-Coto, V. Joshi, R. D. Parsons and J. A. Hinton A&A, 636 (2020) A113 Published online: 28 April 2020 DOI: 10.1051/0004-6361/201936505