THE INCLINATION ANGLE AND EVOLUTION OF THE BRAKING INDEX OF PULSARS WITH PLASMA-FILLED MAGNETOSPHERE: APPLICATION TO THE HIGH BRAKING INDEX OF PSR J1640-4631

• Published in: The Astrophysical journal Vol. 823; no. 1; p. 34
• Main Authors: Ek i, K. Y., Andaç, I. C., Ç k nto lu, S., Gügercino lu, E., Motlagh, A. Vahdat, K z ltan, B.
• Format: Journal Article
• Language: English
• Published: United States The American Astronomical Society 20.05.2016
• Subjects: ACCURACY; ALIGNMENT; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Braking; Crabs; Evolution; INCLINATION; Inclination angle; MAGNETIC DIPOLES; Mathematical models; PLASMA; PULSARS; pulsars: general; pulsars: individual (PSR J1640-4631); SPIN; STAR EVOLUTION; STARS; stars: evolution
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/823/1/34

ABSTRACT The recently discovered rotationally powered pulsar PSR J1640-4631 is the first to have a braking index measured, with high enough precision, that is greater than 3. An inclined magnetic rotator in vacuum or plasma would be subject not only to spin-down but also to an alignment torque. The vacuum model can address the braking index only for an almost orthogonal rotator, which is incompatible with the single-peaked pulse profile. The magnetic dipole model with the corotating plasma predicts braking indices between 3 and 3.25. We find that the braking index of 3.15 is consistent with two different inclination angles, 18 5 3° and 56° 4°. The smaller angle is preferred given that the pulse profile has a single peak and the radio output of the source is weak. We infer the change in the inclination angle to be at the rate −0 23 per century, three times smaller in absolute value than the rate recently observed for the Crab pulsar.