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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Extragalactic radio sources with sharply inverted spectrum at metre wavelengths
Monthly Notices of the Royal Astronomical Society, Volume 443, No. 3, Year 2014
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Description
We present the first results of a systematic search for the rare extragalactic radio sources showing an inverted (integrated) spectrum, with spectral index α ≥ +2.0, a previously unexplored spectral domain. The search is expected to yield strong candidates for α ≥+2.5, for which the standard synchrotron self-absorption (characterized by a single power-law energy distribution of relativistic electron population) would not be a plausible explanation, even in an ideal case of a perfectly homogeneous source of incoherent synchrotron radiation. Such sharply inverted spectra, if found, would require alternative explanations, e.g. free-free absorption, or non-standard energy distribution of relativistic electrons which differs from a power law (e.g. Maxwellian). The search was carried out by comparing two sensitive low-frequency radio surveys made with sub-arcminute resolution, namely, the Westerbork In the Southern Hemisphere (WISH) survey at 352 MHz and TGSS/DR5 at 150 MHz. The overlap region between these two surveys contains 7056 WISH sources classified as 'single' and brighter than 100 mJy at 352 MHz. We focus here on the seven of these sources for which we find α > +2.0. Two of these are undetected at 150 MHz and are particularly good candidates for α > +2.5. Five of the seven sources exhibit a 'Gigahertz-Peaked-Spectrum'. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Authors & Co-Authors
Gopal-Krishna,
India, Pune
Inter-university Centre for Astronomy and Astrophysics India
Sirothia, Sandeep K.
India, Pune
National Centre for Radio Astrophysics India
South Africa, Pinelands
Square Kilometre Array, South Africa
South Africa, Grahamstown
Rhodes University
Mhaskey, Mukul
India, Pune
Savitribai Phule Pune University
Ranadive, Pritesh
India, Pune
Savitribai Phule Pune University
Wiita, Paul J.
United States, Ewing
The College of new Jersey
Goyal, Arti
Poland, Krakow
Uniwersytet Jagielloński
Kantharia, N. G.
India, Pune
National Centre for Radio Astrophysics India
Ishwara-Chandra, C. H.
India, Pune
National Centre for Radio Astrophysics India
Statistics
Citations: 9
Authors: 8
Affiliations: 7
Identifiers
Doi:
10.1093/mnras/stu1364
ISSN:
00358711
e-ISSN:
13652966
Research Areas
Cancer
Study Design
Cross Sectional Study
Study Approach
Quantitative