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Abstract

We report new radio timing solutions from a three-year observing campaign
conducted with the MeerKAT and Murriyang telescopes for nine Small Magellanic
Cloud pulsars, increasing the number of characterised rotation-powered
extragalactic pulsars by 40 per cent. We can infer from our determined
parameters that the pulsars are seemingly all isolated, that six are ordinary
pulsars, and that three of the recent MeerKAT discoveries have a young
characteristic age of under 100 kyr and have undergone a spin-up glitch. Two of
the sources, PSRs J0040$-$7337 and J0048$-$7317, are energetic young pulsars
with spin-down luminosities of the order of 10$^{36}$ erg s$^{-1}$. They both
experienced a large glitch, with a change in frequency of about 30 $\mu$Hz, and
a frequency derivative change of order $-10^{-14}$ Hz s$^{-1}$. These glitches,
the inferred glitch rate, and the properties of these pulsars (including
potentially high inter-glitch braking indices) suggest these neutron stars
might be Vela-like repeating glitchers and should be closely monitored in the
future. The position and energetics of PSR J0048$-$7317 confirm it is powering
a new Pulsar Wind Nebula (PWN) detected as a radio continuum source; and
similarly the association of PSR J0040$-$7337 with the PWN of Supernova Remnant
(SNR) DEM S5 (for which we present a new Chandra image) is strengthened.
Finally, PSR J0040$-$7335 is also contained within the same SNR but is a chance
superposition. It has also been seen to glitch with a change of frequency of
$10^{-2}$ $\mu$Hz. This work more than doubles the characterised population of
SMC radio pulsars.