Discovery of the supernova remnant G351.0-5.4^⋆

¹ Universität Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: fdg@hs.uni-hamburg.de
² Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
³ National Institute of Chemical Physics and Biophysics, Ravala 10, 10143 Tallinn, Estonia
⁴ INAF-Osservatorio di Arcetri, Largo Enrico Fermi 5, 50125, Firenze, Italy
⁵ University of California, One Shields Avenue, Davis CA 95616, USA
⁶ Lawrence Livermore National Lab, 7000 East Avenue, Livermore CA 94550, USA
⁷ Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany

Received: 12 May 2014
Accepted: 31 July 2014

Abstract

While searching the NRAO VLA Sky Survey (NVSS) for diffuse radio emission, we have serendipitously discovered extended radio emission close to the Galactic plane. The radio morphology suggests the presence of a previously unknown Galactic supernova remnant. An unclassified γ-ray source detected by EGRET (3EG J1744-3934) is present in the same location and may stem from the interaction between high-speed particles escaping the remnant and the surrounding interstellar medium. Our aim is to confirm the presence of a previously unknown supernova remnant and to determine a possible association with the γ-ray emission 3EG J1744-3934. We have conducted optical and radio follow-ups of the target using the Dark Energy Camera (DECam) on the Blanco telescope at Cerro Tololo Inter-American Observatory (CTIO) and the Giant Meterwave Radio Telescope (GMRT). We then combined these data with archival radio and γ-ray observations. While we detected the extended emission in four different radio bands (325, 1400, 2417, and 4850 MHz), no optical counterpart has been identified. Given its morphology and brightness, it is likely that the radio emission is caused by an old supernova remnant no longer visible in the optical band. Although an unclassified EGRET source is co-located with the supernova remnant, Fermi-LAT data do not show a significant γ-ray excess that is correlated with the radio emission. However, in the radial distribution of the γ-ray events, a spatially extended feature is related to supernova remnant at a confidence level of ~1.5σ. We classify the newly discovered extended emission in the radio band as the old remnant of a previously unknown Galactic supernova: SNR G351.0-5.4.