Axial Ratio of Edge-On Spiral Galaxies as a Test For Extended Bright Radio Halos

Abstract

We use surface brightness contour maps of nearby edge-on spiral galaxies to determine whether extended bright radio halos are common. In particular, we test a recent model of the spatial structure of the diffuse radio continuum by Subrahmanyan and Cowsik which posits that a substantial fraction of the observed high-latitude surface brightness originates from an extended Galactic halo of uniform emissivity. Measurements of the axial ratio of emission contours within a sample of normal spiral galaxies at 1500 MHz and below show no evidence for such a bright, extended radio halo. Either the Galaxy is atypical compared to nearby quiescent spirals or the bulk of the observed high-latitude emission does not originate from this type of extended halo.

6 Pages, 4 Figures, 1 Table; To Appear In ApJ Letters

References in corpus (5)

• Radio observational constraints on Galactic 3D-emission models
• The cold gaseous halo of NGC 891
• Cosmic rays and the magnetic field of the nearby starburst galaxy NGC 253
• A multi-scale study of infrared and radio emission from Scd galaxy M33
• A multi-resolution analysis of the radio-FIR correlation in the Large Magellanic Cloud

Cited by in corpus (9)

• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• The Second Radio Synchrotron Background Workshop: Conference Summary and Report
• The radio continuum perspective on cosmic-ray transport in external galaxies
• A Stimulating Explanation of the Extragalactic Radio Background
• The cosmic radio background from 150 MHz--8.4 GHz, and its division into AGN and star-forming galaxy flux
• Measurement of the Anisotropy Power Spectrum of the Radio Synchrotron Background
• Can the Local Bubble explain the radio background?
• Radio halos of star forming galaxies
• Diffuse Sources, Clustering and the Excess Anisotropy of the Radio Synchrotron Background