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arXiv · 1905.00677

A low-frequency study of recently identified double-double radio galaxies

S. Nandi·D. J. Saikia·R. Roy·P. Dabhade·Y. Wadadekar·J. Larsson·M. Baes·H. C. Chandola·M. Singh
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Abstract

In order to understand the possible mechanisms of recurrent jet activity in radio galaxies and quasars, which are still unclear, we have identified such sources with a large range of linear sizes (220 $-$ 917 kpc), and hence time scales of episodic activity. Here we present high-sensitivity 607-MHz Giant Metrewave Radio Telescope (GMRT) images of 21 possible double-double radio galaxies (DDRGs) identified from the FIRST survey to confirm their episodic nature. These GMRT observations show that none of the inner compact components suspected to be hot-spots of the inner doubles are cores having a flat radio spectrum, confirming the episodic nature of these radio sources. We have indentified a new DDRG with a candidate quasar, and have estimated the upper spectral age limits for eight sources which showed marginal evidence of steepening at higher frequencies. The estimated age limits (11 $-$ 52 Myr) are smaller than those of the large-sized ($\sim$ 1 Mpc) DDRGs.

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S. Nandi, D. J. Saikia, R. Roy, P. Dabhade, Y. Wadadekar, J. Larsson, M. Baes, H. C. Chandola, M. Singh. 2019-05-02. A low-frequency study of recently identified double-double radio galaxies. https://doi.org/10.1093/mnras%2Fstz1184

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