MeerKAT caught a Mini Mouse: serendipitous detection of a young radio pulsar escaping its birth site

Abstract

In MeerKAT observations pointed at a Galactic X-ray binary located on the Galactic plane we serendipitously discovered a radio nebula with cometary-like morphology. The feature, which we named ‘the Mini Mouse’ based on its similarity with the previously discovered ‘Mouse’ nebula, points back towards the previously unidentified candidate supernova remnant G45.24+0.18. We observed the location of the Mini Mouse with MeerKAT in two different observations, and we localised with arcsecond precision the 138 ms radio pulsar PSR J1914+1054g, recently discovered by the FAST telescope, to a position consistent with the head of the nebula. We confirm a dispersion measure of about 418 pc cm−3 corresponding to a distance between 7.8 and 8.8 kpc based on models of the electron distribution. Using our accurate localisation and 2 period measurements spaced 90 days apart we calculate a period derivative of (2.7 ± 0.3) × 10 −14 s s−1. We derive a characteristic age of approximately 82 kyr and a spin down luminosity of 4 × 1035 erg s−1, respectively. For a pulsar age comparable with the characteristic age, we find that the projected velocity of the neutron star is between 320 and 360 km/s if it was born at the location of the supernova remnant. The size of the proposed remnant appears small if compared with the pulsar characteristic age, however the relatively high density of the environment near the Galactic plane could explain a suppressed expansion rate and thus a smaller remnant.

Cannonball or Bowling Ball: Proper Motion and Parallax for PSR J0002+6216

“…The new estimates of proper motion trace back a path directly through the geometric center of the SNR (as seen in Figure 3 and discussed more in Section 4), making a chance association quite unlikely. This geometric argument has been sufficient for other systems such as the recently discovered "Mini Mouse" (Motta et al 2023). If we assume this association to be true, then our best constraints for the distance to the pulsar are once again approximately 1.5-4 kpc (Landecker et al 1982;Hailey & Craig 1994;Fesen et al 1997;Yar-Uyaniker et al 2004), plus an upper limit d  7 kpc derived from X-ray and γ-ray efficiencies (Wu et al 2018;Zyuzin et al 2018).…”

“…In other cases, proper motion measurements either exclude an association or require more complex scenarios to remain tenable (Brisken et al 2006;de Vries et al 2021;Espinoza et al 2022). Pulsars (or PWNs) with large offsets from the geometric center of the SNR, including pulsars outside the SNR (e.g., Ng et al 2012;Motta et al 2023), are especially important for constraining the high birth velocity tail of PSRs (Frail et al 1994;Hobbs et al 2005;Verbunt et al 2017). The burden of proof is high, since in these cases the probability of a chance association is greatly increased (Gaensler & Johnston 1995).…”