Radio Detection of Lat Psrs J1741–2054 and J2032+4127: No Longer Just Gamma-ray Pulsars

Sixteen pulsars have been discovered so far in blind searches of photons collected with the Large Area Telescope on the Fermi Gamma-ray Space Telescope. We here report the discovery of radio pulsations from two of them. PSR J1741–2054, with period P = 413 ms, was detected in archival Parkes telescope data and subsequently has been detected at the Green Bank Telescope (GBT). Its received flux varies greatly due to interstellar scintillation and it has a very small dispersion measure of DM = 4.7 pc cm−3, implying a distance of ≈ 0.4 kpc and possibly the smallest luminosity of any known radio pulsar. At this distance, for isotropic emission, its gamma-ray luminosity above 0.1 GeV corresponds to 25% of the spin-down luminosity of Ė = 9.4× 1033 erg s−1. The gamma-ray profile occupies 1/3 of pulse phase and has three closely-spaced peaks with the first peak lagging the radio pulse by δ = 0.29P. We have also identified a soft Swift source that is the likely X-ray counterpart. In many respects PSR J1741–2054 resembles the Geminga pulsar. The second source, PSR J2032+4127, was detected at the GBT. It has P = 143 ms, and its DM = 115 pc cm−3 suggests a distance of ≈ 3.6 kpc, but we consider it likely that it is located within the Cyg OB2 stellar association at half that distance. The radio emission is nearly 100% linearly polarized, and the main radio peak precedes by δ = 0.15P the first of two narrow gamma-ray peaks that are separated by ∆ = 0.50P. The second peak has a harder spectrum than the first one, following a trend observed in young gamma-ray pulsars. Faint, diffuse X-ray emission in a Chandra image is possibly its pulsar wind nebula. PSR J2032+4127 likely accounts for the EGRET source 3EG J2033+4118, while its pulsar wind is responsible for the formerly unidentified HEGRA source TeV J2032+4130. PSR J2032+4127 is coincident in projection with MT91 213, a Be star in Cyg OB2, although apparently not a binary companion of it. Subject headings: gamma rays: observations — ISM: individual (TeV J2032+4130) — open clusters and associations: individual (Cyg OB2) — pulsars: individual (PSR J1741–2054, PSR J2032+4127) — X-rays: individual (Swift J174157.6–205411) 1 Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA 2 Space Science Division, Naval Research Laboratory, Washington, DC 20375, USA 3 National Radio Astronomy Observatory, Charlottesville, VA 22903, USA 4 INAF — Osservatorio Astronomico di Cagliari, 09012 Capoterra, Italy 5 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 6 University of Maryland, College Park, MD 20742, USA 7 Department of Physics, University of Washington, Seattle, WA 98195, USA 8 Australia Telescope National Facility, CSIRO, Epping, NSW 1710, Australia 9 CSIRO Parkes Observatory, Officer-in-Charge for life, Parkes, NSW 2870, Australia 10 Department of Physics, Stanford University, Stanford, CA 94305, USA 11 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia 12 Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, CA 95064, USA 13 CNRS/IN2P3, Centre d’Études Nucléaires de Bordeaux-Gradignan, Gradignan, 33175, France 14 Université de Bordeaux, Centre d’Études Nucléaires de BordeauxGradignan, Gradignan, 33175, France 15 NRC Research Associate 16 Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604, USA 17 NAIC, Arecibo Observatory, Arecibo, PR 00612, USA 18 MPIfR, 53121 Bonn, Germany 19 Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL, UK 20 Eureka Scientific, Inc., Oakland, CA 94602, USA