The RRAT Trap: Interferometric localization of radio pulses from J0628+0909

Abstract

We present the first blind interferometric detection and imaging of a millisecond radio transient with an observation of transient pulsar J0628+0909.We developed a special observing mode of the Karl G. Jansky Very Large Array to produce correlated data products (i.e., visibilities and images) on a timescale of 10 ms. Correlated data effectively produce thousands of beams on the sky that can localize sources anywhere over a wide field of view. We used this new observing mode to find and image pulses from the rotating radio transient (RRAT) J0628+0909, improving its localization by two orders of magnitude. Since the location of the RRAT was only approximately known when first observed, we searched for transients using a wide-field detection algorithm based on the bispectrum, an interferometric closure quantity. Over 16 minutes of observing, this algorithm detected one transient offset roughly 1′ from its nominal location; this allowed us to image the RRAT to localize it with an accuracy of 1. ′′6. With a priori knowledge of the RRAT location, a traditional beam-forming search of the same data found two lower significance pulses. The refined RRAT position excludes all potential multiwavelength counterparts, limiting its optical luminosity to L i′ < 1.1 × 1031 erg s-1 and disfavoring source models with luminous neutron stars. © 2012. The American Astronomical Society. All rights reserved.