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Paper: A GMRT Search for Relic Radio Emission
Volume: 407, The Low-Frequency Radio Universe
Page: 204
Authors: Sirothia, S.K.; Saikia, D.J.; Ishwara-Chandra, C.H.; Kantharia, N.G.
Abstract: We present deep multifrequency observations using the Giant Metrewave Radio Telescope at 153, 244, 610 and 1260 MHz of a field centered on J0916+6348, to search for evidence of fossil radio lobes which could be due to an earlier cycle of episodic activity of the parent galaxy, as well as halos and relics in clusters of galaxies. We do not find any unambiguous evidence of episodic activity in a list of 374 sources, suggesting that such activity is rare even in relatively deep low-frequency observations. We find that almost all sources are consistent with a straight spectrum with a median spectral index, α ~0.8 [S(v) ∝ v−α], which appears steeper than theoretical expectations of the injection spectral index. We identify 14 very steep-spectrum sources with α ≥1.3. We examine their optical fields and discuss the nature of some of these sources.
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