Spectral ageing analysis of the double–double radio galaxy J1453+3308 |
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| Authors: | C Konar D J Saikia M Jamrozy J Machalski |
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| Institution: | National Centre for Radio Astrophysics, TIFR, Pune University Campus, Post Bag 3, Pune 411 007, India;Obserwatorium Astronomiczne, Uniwersytet Jagielloński, ul. Orla 171, 30244 Kraków, Poland |
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| Abstract: | We present new radio observations at frequencies ranging from 240 to 4860 MHz of the well-known, double–double radio galaxy (DDRG), J1453+3308, using both the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA). These observations enable us to determine the spectra of the inner and outer lobes over a large frequency range and demonstrate that while the spectrum of the outer lobes exhibits significant curvature, that of the inner lobes appears practically straight. The break frequency, and hence the inferred synchrotron age of the outer structure, determined from 16-arcsec strips transverse to the source axis, increases with distance from the heads of the lobes. The maximum spectral ages for the northern and southern lobes are ～47 and 58 Myr, respectively. Because of the difference in the lengths of the lobes, these ages imply a mean separation velocity of the heads of the lobes from the emitting plasma of 0.036 c for both the northern and southern lobes. The synchrotron age of the inner double is about 2 Myr which implies an advance velocity of ～0.1 c , but these values have large uncertainties because the spectrum is practically straight. |
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| Keywords: | galaxies: active galaxies: individual: J1453+3308 galaxies: nuclei radio continuum: galaxies |
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