INAF - Brera Astronomical Observatory; Astronomical Institute ‘Anton Pannekoek’ - University of Amsterdam; Vidi award - Netherlands Organization for Scientific Research; European Cooperation in Science and Technology Action MP1304 ‘Exploring fundamental physics with compact stars’ (NewCompStar)

Observing neutron stars at the magnetic extremes.

The radio-emitting neutron star population encompasses objects with spin periods ranging from milliseconds to tens of seconds. As they age and spin more slowly, their radio emission is expected to cease. We present the discovery of an ultra-long period radio-emitting neutron star, PSR J0901-4046, with spin properties distinct from the known spin and magnetic-decay powered neutron stars. With a spin-period of 75.88 s, a characteristic age of 5.3 Myr, and a narrow pulse duty-cycle, it is uncertain how radio emission is generated and challenges our current understanding of how these systems evolve. The radio emission has unique spectro-temporal properties such as quasi-periodicity and partial nulling that provide important clues to the emission mechanism. Detecting similar sources is observationally challenging, which implies a larger undetected population. Our discovery establishes the existence of ultra-long period neutron stars, suggesting a possible connection to the evolution of highly magnetized neutron stars, ultra-long period magnetars, and fast radio bursts. 

/pdf/discovery-of-a-radio-emitting-neutron-star-with-an-ultra-35jhvrpk.pdf

Discovery of a radio emitting neutron star with an ultra-long spin period of 76 seconds

A model for the main observational characteristics of the radio emission of pulsars with well organized drifting subpulses is presented. We propose that drifting subpulses result from the modulation of the radio emission mechanism due to long-wavelength drift waves in the magnetosphere. The drift waves are generated at shorter wavelengths, and their nonlinear evolution favours accumulation in a specific azimuthal eigenmode with an integral number, $m$, of nodes encircling the magnetic pole. The electric field of the drift waves is along the magnetic field lines, and this modulates the distribution for particles and hence the radio emission mechanism. The ratio of the frequency of the eigenmode to the rotation frequency of the star is insensitive to the magnetic field strength and the period of rotation, and is of order unity. The period, $P_3$, of the drifting subpulses is attributed to the mismatch between this frequency and the nearest harmonic of the rotation frequency of the star.

On the origin of the drifting subpulses in radio pulsars

На Жаботинському поселенні раннього залізного віку (Кам'янський р‐н, Черкаська обл. )
магнітометричним методом було простежено рів, що розділяє надвоє його центральну
частину. У результаті археологічних розкопок у заповненні рову виділені окремі шари з
характерною магнітною сприйнятливістю і відображають всю послідовність нашарувань 8‐7 і
початку 6 ст. до н.е. на поселенні. Показано, що магнітна аномалія над ровом викликана
переважно будівельними горизонтами, які датуються кінцем 8‐го серединою 7‐го ст. до н.е.

Магнітні дослідження та структура рову Жаботинського поселення раннього залізного віку

The pair of drifting subpulses of the radio pulsar PSR B0031-07 appear to be well separated from each other on the average, overlapping at less than one thirtieth of the peak energy. Strictly, the integrated profile of the pair (after removing the drift) does not show more than two subpulses; however this result is likely to be modified with the availability of more data. On the other hand, rare instances of three simultaneous subpulses in a single period have been noticed. This is consistent with the Ruderman and Sutherland model of the drifting phenomenon in which several sparks, uniformly spaced on a circle, rotate around the polar cap. The third subpulse appears to show up strongly when subpulses belonging to the primary drift bands weaken. Although this conclusion is based mainly on two reliable examples, it suggests an anti correlation of the subpulse energies. The normalised correlation coefficient between the energies of the two subpulses in a period is -0.16 +- 0.02, after accounting for a known selection effect. Simulations suggest that this result could not be an artefact. This suggests the idea of competing drifting subpulses which, if true, will have important ramifications for the growth and breakdown of the particle acceleration zones in pulsars.

https://arxiv.org/pdf/astro-ph/9812139.pdf

P. G. Sutherland

Papers

Theory of pulsars: Polar gaps, sparks, and coherent microwave radiation