A radio continuum and polarization study of the pulsar wind nebula CTB 87 (G74.9+1.2). Issue 1 (11th June 2020)

• Record Type: Journal Article
• Authors: Kothes, R; Reich, W; Safi-Harb, S; Guest, B; Reich, P; Fürst, E
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 496:Issue 1(2020)
• Page Start: 723
• Page End: 738
• Publication Date: 2020-06-11
• Subjects: magnetic fields -- polarization -- ISM: individual objects: CTB 87 -- ISM: magnetic fields -- ISM: supernova remnants; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1573
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present radio continuum and linear polarization observations of the pulsar wind nebula (PWN) CTB 87 (G74.9+1.2) with the Effelsberg 100-m Radio Telescope between 4.75 and 32 GHz. An analysis of these new data including archived low-frequency observations at 1420 and 408 MHz from the Canadian Galactic Plane Survey shows that CTB 87 consists of two distinct emission components: a compact kidney-shaped component, 14 × 8.5 pc 2 (7.8 × 4.8 arcmin 2 ) in size and a larger diffuse, spherical, and centrally peaked component of about 30 pc (17 arcmin) in diameter. The kidney-shaped component with a much steeper radio continuum spectrum is highly linearly polarized and likely represents a relic PWN. The diffuse component represents the undisturbed part of the PWN expanding inside a cavity or stellar wind bubble. The previously reported spectral break above 10 GHz is likely the result of missing large-scale emission and insufficient sensitivity of the high-frequency radio continuum observations. The simulation of the system's evolution yields an age of about 18 000 yr as the result of a Type II supernova explosion with ejecta mass of about 12 M⊙ and explosion energy of about 7 × 10 50 erg. We also found evidence for a radio shell in our polarization data that represents the blast wave that entered the molecular cloud complex at a radius of about 13 pc.