Detection of a persistent radio source at the location of FRB20201124A with VLA

ATel #14549; Roberto Ricci (INAF/IRA), Luigi Piro (INAF/IAPS), Francesca Panessa (INAF/IAPS), Brendan O'Connor (George Washington University), Simone Lotti (INAF/IAPS), Gabriele Bruni(INAF/IAPS) , Bing Zhang (University of Nevada)
on 14 Apr 2021; 21:18 UT
Credential Certification: Luigi Piro (luigi.piro@inaf.it)

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We observed the location of FRB 20201124A with the VLA (Program SG9112, PI: Piro) on April 9 for 2 hours, starting at UTC 2021-04-09T23:51:37. Observations were carried out with the array in configuration D, in the S and X bands (3 and 9 GHz respectively), corresponding to a X-band beam size of 7x6 arcsec. We detect an unresolved persistent radio source with a flux density of 0.34 +/- 0.03 mJy at 3GHz and 0.15+/-0.01 mJy at 9 GHz at a position (epoch J2000) of (RA, Dec) = (05:08:03.49, +26:03:37.6) with a 5 sigma positional uncertainty of about 1 arcsec. This radio source is coincident with the persistent radio source detected by uGMRT (Atel#14529), with the VLA/realfast burst position (ATel #14526), with the FAST position (ATel #14518) and with the location of the galaxy SDSS J050803.48+260338.0 (ATel #14516), but offset by about 3.3 arcsec from the latest ASKAP burst position (ATel #14515). We note that the radio power at 3 and 9 GHz is Log P = 21.88 and 21.54 W/Hz (respectively). The spectral index between the uGMRT measurement at 0.65 GHz and our 3 GHz data point is about -0.5 while it steepens between 3 and 9 GHz (~0.7). Taking the X-ray upper limit from our SWIFT observation (ATel#14525) and assuming that the radio emission is produced by an AGN, we derive a lower limit to the X-ray radio-loudness calculated as Log(Lr/Lx) <-4 (Terashima & Wilson 2003, ApJ 543, 185), a typical value for Radio Quiet AGN. Further observations are planned to assess the nature of the persistent radio emission.