Ultraslow PSR J0901-4046 with an ultrahigh magnetic field of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>3.2</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>16</mml:mn></mml:mrow></mml:msup><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi mathvariant="normal">G</mml:mi></mml:mrow></mml:math>
D. N. Sob’yanin
Abstract
The recent discovery of a radio-emitting neutron star with an ultralong spin period of 76 s, PSR J0901-4046, raises a fundamental question on how such a slowly rotating magnetized object can be active in the radio band. A canonical magnetic field of $1.3\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{ }\mathrm{G}$ estimated from the pulsar period and its time derivative is wholly insufficient for PSR J0901-4046 to operate. Consideration of a magnetic inclination angle of 10\ifmmode^\circ\else\textdegree\fi{} estimated from the pulse width gives a higher magnetic field of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{15}\text{ }\text{ }\mathrm{G}$, which is still an order of magnitude lower than the necessary minimum of $2.5\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{G}$ following from the death line for radio pulsars with magnetic fields exceeding the critical value $4.4\ifmmode\times\else\texttimes\fi{}{10}^{13}\text{ }\text{ }\mathrm{G}$. We show that if the observed microstructure of single pulses reflects relativistic beaming, the inferred surface magnetic field appears to be $3.2\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{G}$, and without this assumption it is no less than $2.7\ifmmode\times\else\texttimes\fi{}{10}^{16}\text{ }\text{ }\mathrm{G}$, which explains the existence of radio emission from PSR J0901-4046. This estimation makes PSR J0901-4046 a radio pulsar with the strongest magnetic field known and is a sign that PSR J0901-4046 slows down not by magnetic-dipole radiation, but rather by an electric current of 56 MA, when rotational energy is expended in accelerating charged particles over the polar cap.