Correlated spin-down rates and radio emission in PSR B1859+07
Abstract
We study the spin-down changes of PSR B1859+07 over a period of more than 28 years of radio observation. We identify that the time derivative of the rotational frequency (ν) varies quasi-periodically with a period of ∼350 d, switching mainly between two spin-down states. The profile shape of the pulsar is correlated with the ν˙ variation, producing two slightly different profile shapes corresponding to high- and low-ν˙ states. In addition to these two normal emission states, we confirm the occasional flare-state of the pulsar, in which the emission appears early in spin phase compared to that of the common normal emission. The profile of the flare-state is significantly different from that of the two normal emission states. The correlation analysis further shows that the flare-state is not directly linked with the ν˙ changes. With a simple emission beam model, we estimate the emission altitude of the normal emission to be 240 km, and explain the origin of the flare-state as an emission height variation from the leading edge of the beam. We also argue that the emission of these states can be explained with a partially active beam model. In this scenario, the trailing portion of the radio beam is usually active and the normal emission is produced. The flare-state occurs when the leading edge of the beam becomes active while the trailing part is being blocked. This model estimates a fixed emission altitude of 360 km. However, the cause of the flare-state (I.e. the emission height variation, or the time-dependent activity across the radio beam) is not easily explained.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2016
- DOI:
- 10.1093/mnras/stv2403
- arXiv:
- arXiv:1510.04484
- Bibcode:
- 2016MNRAS.455.1071P
- Keywords:
-
- stars: neutron;
- pulsars: general;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 9 pages, 8 figures, Accepted by MNRAS on 14 October 2015