Detection of continuum radio emission associated with Geminga

TL;DR

Deep VLA observations revealed a faint, extended radio tail behind the Geminga pulsar, likely associated with its pulsar wind nebula, suggesting similar features might be detectable in other nearby radio-quiet pulsars.

Contribution

First detection of a radio tail associated with Geminga, linking radio emission to its pulsar wind nebula and expanding understanding of pulsar environments.

Findings

Radio tail is marginally displaced from Geminga pulsar

Radio feature is compatible with synchrotron emission from PWN

Other nearby radio-quiet pulsars may exhibit similar structures

Abstract

A deep Very Large Array observation of the Geminga pulsar field led to the discovery, at a higher than 10 sigma significance level, of radio emission trailing the neutron star proper motion. This 10-arcsec-long radio feature, detected with a flux of 0.4 mJy at 4.8 GHz, is marginally displaced (2.7\pm1.8 arcsec) from the pulsar (which, at any rate, is unlikely to contribute with magnetospheric pulsed emission more than 15% to the total observed radio luminosity, about 1E26 erg/s) and positionally coincident with the X-ray axial tail recently discovered by Chandra and ascribed to the pulsar wind nebula (PWN). Overall, the Geminga radio tail is compatible with the scenario of a synchrotron-emitting PWN, but the present data do not allow us to discriminate between different (and not always necessarily mutually exclusive) possible processes for producing that. If this radio feature does not result from intrinsic peculiarities of Geminga, but its proximity and radio-quiet nature (both helping in not hindering the faint diffuse radio emission), other relatively near and energetic radio-quiet pulsars could show similar structures in dedicated interferometric observations.