A New, Low Braking Index For the LMC Pulsar B0540-69

Abstract

We report the results of a 16-month monitoring campaign using the Swift satellite of PSR B0540-69, a young pulsar in the Large Magellanic Cloud. Phase connection was maintained throughout the campaign so that a reliable ephemeris could be determined, and the length of the campaign is adequate to accurately determine the spin frequency and its first and second derivatives. The braking index is 0.031 +/- 0.013 (90% confidence), a value much lower than previously reported for B0540-69 and almost all other young pulsars. We use data from the extensive monitoring campaign with RXTE to show that timing noise is unlikely to significantly affect the measurement. This is the first measurement of the braking index in the pulsar's recently discovered high spin-down state. We discuss possible mechanisms for producing the low braking index.

6 pages, 1 figure accepted for publication in ApJ Letters

References in corpus (9)

• The ATNF Pulsar Catalogue
• Switched magnetospheric regulation of pulsar spin-down
• A periodically active pulsar giving insight into magnetospheric physics
• 45 Years of Rotation of the Crab Pulsar
• Predicting the Starquakes in PSR J0537-6910
• Magnetic field growth in young glitching pulsars with a braking index
• Hall drift and the braking indices of young pulsars
• The unusual glitch recoveries of the high magnetic field pulsar J1119$-$6127
• Discovery of a Spin-Down State Change in the LMC Pulsar B0540-69

Cited by in corpus (16)

• The Third Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• Pulsar braking and the P-Pdot diagram
• Central Compact Objects in Supernova Remnants
• The braking index of millisecond magnetars
• The glitches and rotational history of the highly energetic young pulsar PSR J0537$-$6910
• The Braking Index of a Radio-quiet Gamma-ray Pulsar
• Learning About the Magnetar Swift J1834.9-0846 from its Wind Nebula
• Discovery of the first anti-glitch event in the rotation-powered pulsar PSR B0540-69
• A spider timing model: accounting for quadrupole deformations and relativity in close pulsar binaries
• Proper motion, spectra, and timing of PSR J1813-1749 using Chandra and NICER
• The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition
• Refinement of the timing-based estimator of pulsar magnetic fields
• Braking index jumps in young pulsars
• Spatial Variations and Breaks in the Optical-NIR spectra of the Pulsar and PWN in SNR 0540-69.3
• A growing braking index and spin-down swings for the pulsar PSR B0540-69
• Gamma-ray flares from pulsar wind nebulae in the Large Magellanic Cloud