2003/03/05 by D. L. Kaplan, M. H. van Kerkwijk, H. L. Marshall +3 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/375052
published as Astrophys.J. 590 (2003) 1008-1019 · 13 pages, 9 figures. Uses emulateapj5.sty and onecolfloat5.sty. Accepted for publication in ApJ
arxiv created 2003/03/05 · openalex publication_date 2003/06/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present radio, optical, ultraviolet, and X-ray observations of the isolated, thermally emitting neutron star RX J0720.4-3125 using the Parkes radio telescope, the Very Large Array, the Hubble Space Telescope , and the Chandra X-Ray Observatory . From these data we show that the optical/UV spectrum of RX J0720.4-3125 is not well fitted by a Rayleigh-Jeans tail as previously thought but is instead best fitted by either a single nonthermal power law or a combination of a Rayleigh-Jeans tail and a nonthermal power law. Taken together with the X-ray spectrum, we find the best model for RX J0720.4-3125 to be two blackbodies plus a power law, with the cool blackbody implying a radius of 11-13 km at an assumed distance of 300 pc. This is similar to many middle-aged (10 5 -10 6 yr) radio pulsars such as PSR B0656+14, evidence supporting the hypothesis that RX J0720.4-3125 is likely to be an off-beam radio pulsar. The radio data limit the flux at 1.4 GHz to be less than 0.24 mJy, or a luminosity limit of 4π d 2 F < 3 × 10 25 d ergs s -1 , and we see no sign of extended nebulosity, consistent with expectations for a pulsar like RX J0720.4-3125.