title: A double-pulsar system: a rare laboratory for relativistic gravity and plasma physics.
abstract: The clocklike properties of pulsars moving in the gravitational fields of their unseen neutron-star companions have allowed unique tests of general relativity and provided evidence for gravitational radiation. We report here the detection of the 2.8-second pulsar J0737-3039B as the companion to the 23-millisecond pulsar J0737-3039A in a highly relativistic double neutron star system, allowing unprecedented tests of fundamental gravitational physics. We observed a short eclipse of J0737-3039A by J0737-3039B and orbital modulation of the flux density and the pulse shape of J0737-3039B, probably because of the influence of J0737-3039A's energy flux on its magnetosphere. These effects will allow us to probe magneto-ionic properties of a pulsar magnetosphere.
authors.affiliation: Jodrell Bank Observatory, University of Manchester, Macclesfield SK11 9DL, UK. agl@jb.man.ac.uk
authors.forename: A G
authors.initials: AG
authors.lastname: Lyne
authors.forename: M
authors.initials: M
authors.lastname: Burgay
authors.forename: M
authors.initials: M
authors.lastname: Kramer
authors.forename: A
authors.initials: A
authors.lastname: Possenti
authors.forename: R N
authors.initials: RN
authors.lastname: Manchester
authors.forename: F
authors.initials: F
authors.lastname: Camilo
authors.forename: M A
authors.initials: MA
authors.lastname: McLaughlin
authors.forename: D R
authors.initials: DR
authors.lastname: Lorimer
authors.forename: N
authors.initials: N
authors.lastname: D'Amico
authors.forename: B C
authors.initials: BC
authors.lastname: Joshi
authors.forename: J
authors.initials: J
authors.lastname: Reynolds
authors.forename: P C C
authors.initials: PC
authors.lastname: Freire