Discovery of a Spin-down State Change in the LMC Pulsar B0540-69

F. E. Marshall (1) , Lucas Guillemot (2, 3) , A. K. Harding (1) , P. Martin (4) , D. A. Smith (5)

1 GSFC Astrophysics Science Division
2 USN - Unité Scientifique de la Station de Nançay
3 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
4 IRAP - Institut de recherche en astrophysique et planétologie
5 CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan

We report the discovery of a large, sudden, and persistent increase in the spin-down rate of B0540-69, a young pulsar in the Large Magellanic Cloud, using observations from the Swift and RXTE satellites. The relative increase in the spin-down rate $\dot{\nu }$ of 36% is unprecedented for B0540-69. No accompanying change in the spin rate is seen, and no change is seen in the pulsed X-ray emission from B0540-69 following the change in the spin-down rate. Such large relative changes in the spin-down rate are seen in the recently discovered class of "intermittent pulsars," and we compare the properties of B0540-69 to such pulsars. We consider possible changes in the magnetosphere of the pulsar that could cause such a large change in the spin-down rate.

Domains: Solar and Stellar Astrophysics [astro-ph.SR]

F. E. Marshall, Lucas Guillemot, A. K. Harding, P. Martin, D. A. Smith. Discovery of a Spin-down State Change in the LMC Pulsar B0540-69. The Astrophysical journal letters, 2015, 807 (2), pp.L27. ⟨10.1088/2041-8205/807/2/L27⟩. ⟨insu-01182158⟩