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Implications of the lowest frequency detection of the persistent counterpart of FRB121102
- Source :
- A&A 655, A102 (2021)
- Publication Year :
- 2020
-
Abstract
- Context. The repeating FRB121102 is so far the only extra-galactic Fast Radio Burst found to be associated with a counterpart, a steady radio source with a nearly flat spectral energy distribution (SED) in centimeter wavelengths. Aims. Previous observations of the persistent source down to $1.6$~GHz has shown no sign of a spectral turn-over. Absorption is expected to eventually cause a turn-over at lower frequencies. Better constraints on the physical parameters of the emitting medium can be derived by detecting the self-absorption frequency. Methods. We used the Giant Metre-Wave Radio Telescope (GMRT) during the period of July to December 2017 to observe the source at low radio frequencies down to $400$~MHz. Results. The spectral energy distribution of the source remains optically thin even at $400$~MHz, with a spectral index of $\nu^{-(0.07 \pm 0.03)}$ similar to what is seen in Galactic plerions. Using a generic synchrotron radiation model, we obtain constraints on properties of the non-thermal plasma and the central engine powering it. Conclusions. We present low-frequency detections of the persistent source associated with FRB121102. Its characteristic flat SED extends down to $400$~MHz. Like Galactic plerions, the energy in the persistent source is carried predominantly by leptons. The emitting plasma has a $B< 0.01$~G, and its age is $> 524 \left(\frac{B}{0.01 {\rm G}} \right)^{-3/2}$. We show that the energetics of the persistent source requires an initial spin period shorter than 36~ms, and the magnetic field of the neutron star must exceed $4.5\times 10^{12}$~G. This implies that the persistent source does not necessarily require energetic input from a magnetar.<br />Comment: Submitted to A&A, 8 pages, 4 figures
- Subjects :
- Astrophysics - High Energy Astrophysical Phenomena
Subjects
Details
- Database :
- arXiv
- Journal :
- A&A 655, A102 (2021)
- Publication Type :
- Report
- Accession number :
- edsarx.2010.14334
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1051/0004-6361/202039771