A strong upper limit on the pulsed radio luminosity of the compact object 1RXS J141256.0+792204

¹ Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands e-mail: jhessels@science.uva.nl
² Stichting ASTRON, Postbus 2, 7990 AA Dwingeloo, The Netherlands e-mail: stappers@astron.nl
³ Department of Physics, McGill University, 3600 University, H3A 2T8 Montreal, QC, Canada e-mail: rutledge@physics.mcgill.ca
⁴ Department of Astronomy & Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802, USA e-mail: dfox@astro.psu.edu, ahs148@psu.edu

Received: 21 July 2007
Accepted: 11 October 2007

Abstract

Context.The ROSAT X-ray source 1RXS J141256.0+792204 has recently been identified as a likely compact object whose properties suggest it could be a very nearby radio millisecond pulsar at  pc.

Aims.We investigated this hypothesis by searching for radio pulsations using the Westerbork Synthesis Radio Telescope.

Methods.We observed 1RXS J141256.0+792204 at 385 and 1380 MHz, recording at high time and frequency resolution in order to maintain sensitivity to millisecond pulsations. These data were searched both for dispersed single pulses and using Fourier techniques sensitive to constant and orbitally modulated periodicities.

Results.No radio pulsations were detected in these observations, resulting in pulsed radio luminosity limits of ≈ 0.3 (d/250 pc)² mJy kpc² and ≈ 0.03 (d/250 pc)² mJy kpc² at 400 and 1400 MHz respectively.

Conclusions.The lack of detectable radio pulsations from 1RXS J141256.0+792204 brings into question its identification as a nearby radio pulsar, though, because the pulsar could be beamed away from us, this hypothesis cannot be strictly ruled out.