PSR J0901-4046 is the most magnetized radio pulsar known, according to a study

The background of both images shows continuous 1.28 GHz radio emission from the nebula surrounding the high-mass X-ray binary system Vela X-1, and its newly discovered radio arc shock (van den Eijnden et al. 2022). On the left and right we can see the MeerKAT images of the pulsar PSR J0901-4046 before and during a pulse, respectively. Credit: Ian Heywood.

Astronomers have investigated an ultra-slow radio pulsar known as PSR J0901-4046 and found that it has an extremely high magnetic field, at a level of 30 quadrillion Gauss. The discovery, published April 7 in Physical Review D, makes PSR J0901-4046 the most magnetized radio pulsar known to date. Extraterrestrial sources of radiation with a regular periodicity, known as pulsars, are usually detected in the form of short bursts of radio emission. Radio pulsars are generally described as rapidly rotating, highly magnetized neutron stars with a beam of radiation light that produces the pulsed emission.

PSR J0901-4046 was discovered on September 27, 2020 at 1284 MHz with the MeerKAT radio telescope and was associated with an ultra-slowly rotating magnetized neutron star. It has an ultra-long spin period of approximately 75.9 seconds, making it spin more than three times slower than the previous record holder PSR J0250+5854.

The strength of the surface magnetic field of PSR J0901-4046 was initially estimated at a level of 130 trillion Gauss, depending on its period. However, later studies found that such a magnetic field is totally insufficient for this pulsar to work, excluding the hypothesis that PSR J0901-4046 may be a magnetar. In addition, it was not clear how such a slowly rotating source is still active in the radio band. That’s why a team of astronomers led by Denis Sob’yanin of the P.N. Lebedev Institute of Physics of the Russian Academy of Sciences in Moscow, Russia, decided to take a closer look at PSR J0901-4046. “In this paper, we address the problem of the origin of the radio emission from the apparently dead PSR J0901-4046. Avoiding the magnetic dipole radiation model and using only the energy transformation during plasma multiplication over the polar cap of a strongly magnetized rotating neutron star, we show that the actual surface magnetic field of PSR J0901-4046 is 2 orders of magnitude. higher than the conventional estimate,” the researchers explained.

The study found that PSR J0901-4046 has a magnetic field of at least 27 quadrillion Gauss. Such a strong magnetic field explains the existence of plasma multiplication and the observed radio emission from this pulsar. Thus, PSR J0901-4046 becomes the most magnetized radio pulsar discovered so far. The astronomers explained that the ultra-slow rotation of PSR J0901-4046 implies that the intensity of the surface magnetic field should exceed the value of 25 quadrillion Gauss. This is necessary for an efficient cascade multiplication of an electron-positron plasma that generates a radio emission.

The researchers added that the extremely strong magnetic field of PSR J0901-4046 indicates that the pulsar is slowed down not by radiation from the magnetic dipole, but by an electrical current of about 56 megaamps, when rotational energy is spent accelerating charged particles. over the pole. cap. In this scenario, the rotational energy of the neutron star is completely transformed into the energy of the primary particles in the acceleration gap, and not into the energy of the radiation from the magnetic dipole.