East Asia VLBI Network observations of the TeV Gamma-Ray Burst 190114C

Abstract

Observations of gamma-ray bursts (GRBs) at Very High Energy (VHE) offer a unique opportunity to investigate particle acceleration processes, magnetic fields and radiation fields in these events. Very Long Baseline Interferometry (VLBI) observations have been proven to be a powerful tool providing unique information on the source size of the GRBs at mas scales, as well as their accurate positions and possible expansion speeds. This paper reports on the follow-up observations of GRB 190114C, the first ever GRB detected with high significance at TeV photon energies by the MAGIC telescope, conducted with the East Asia VLBI Network (EAVN) at 22 GHz on three epochs, corresponding to 6, 15 and 32 days after the burst. The derived maps do not show any significant source above 5σ. The inferred upper limits on the GRB 190114Cflux density at 22 GHz are used here to constrain the allowable two-dimensional parameter space for the afterglow emission. We find that our limits are consistent with most afterglow parameter combinations proposed so far in the literature. This is the first effort for the EAVN to search and monitor a radio transient in the Target of Opportunity mode. In addition to the useful constraints on GRB 190114C radio emission, experience gained from these observations is very helpful for future routine operation of EAVN transient program. techniques: interferometric -galaxies: active -gamma rays: bursts -individual: GRB 190114C PACS number(s): Citation: An et al, , 60, 000000 (2019), doi:

Methods for detection and analysis of weak radio sources with single-dish radio telescopes

“…From the analysis of real images, we do not detect the afterglows of either 181201A or 190114C in any images at S 5. Our upper limits lie above the VLA and ATCA flux densities [23,35] and East Asia VLBI upper limits [54] obtained almost at the same epoch. In particular, our upper limit of 17 January 2019 for 190114C (1.8 mJy), estimated with Method C in fixed position case (Table 2), lies just above the interpolated ATCA flux density (∼ 1.6 mJy) calculated in C-band (6.9 GHz) at the time of SRT observation (2.9 d after the GRB trigger).…”

East Asian VLBI Network observations of active galactic nuclei jets: imaging with KaVA+Tianma+Nanshan

“…In fact, we analyzed some more recent KaVA+TMRT+NSRT data obtained by an open-sky program, and we confirmed good consistency of the array performance as reported here. Various scientific results based on EAVN data are currently being produced (e.g., gamma-ray bursts, An et al 2020). The detailed results of M87 and Sgr A obtained 3 https://radio.kasi.re.kr/eavn/about_eavn.php from recent EAVN observations will be reported in Cui et al (2021) (in preparation) and Cho et al (2021) (in preparation).…”

East Asian VLBI Network Observations of Active Galactic Nuclei Jets: Imaging with KaVA+Tianma+Nanshan

“…In fact, we analyzed some of more recent KaVA+TMRT+NSRT data obtained by an open-sky program, and we confirmed good consistency of the array performance as reported here. Various scientific results based on EAVN data are currently being produced (e.g., gamma-ray bursts, An et al 2020). The detailed results of M 87 and SgrA obtained from recent EAVN observations will be reported in Cui et al 2021 (in preparation) and Cho et al 2021 (in preparation).…”