scholarly journals Radio afterglows of very high-energy gamma-ray bursts 190829A and 180720B

2020 ◽  
Vol 496 (3) ◽  
pp. 3326-3335 ◽  
Author(s):  
L Rhodes ◽  
A J van der Horst ◽  
R Fender ◽  
I M Monageng ◽  
G E Anderson ◽  
...  

ABSTRACT We present high-cadence multifrequency radio observations of the long gamma-ray burst (GRB) 190829A, which was detected at photon energies above 100 GeV by the High Energy Stereoscopic System (H.E.S.S.). Observations with the Meer Karoo Array Telescope (MeerKAT, 1.3 GHz) and Arcminute Microkelvin Imager – Large Array (AMI-LA, 15.5 GHz) began one day post-burst and lasted nearly 200 d. We used complementary data from Swift X-Ray Telescope (XRT), which ran to 100 d post-burst. We detected a likely forward shock component with both MeerKAT and XRT up to over 100 d post-burst. Conversely, the AMI-LA light curve appears to be dominated by reverse shock emission until around 70 d post-burst when the afterglow flux drops below the level of the host galaxy. We also present previously unpublished observations of the other H.E.S.S.-detected GRB, GRB 180720B from AMI-LA, which shows likely forward shock emission that fades in less than 10 d. We present a comparison between the radio emission from the three GRBs with detected very high energy (VHE) gamma-ray emission and a sensitivity-limited radio afterglow sample. GRB 190829A has the lowest isotropic radio luminosity of any GRB in our sample, but the distribution of luminosities is otherwise consistent, as expected, with the VHE GRBs being drawn from the same parent distribution as the other radio-detected long GRBs.

2010 ◽  
Vol 19 (06) ◽  
pp. 1013-1022
Author(s):  
◽  
ULISSES BARRES DE ALMEIDA

The High Energy Stereoscopic System (H.E.S.S.) is a southern hemisphere array of four Imaging Atmospheric Cherenkov Telescopes observing the sky in the very-high energy gamma-ray range (E > 100 GeV ). VHE observations are an invaluable tool to study the acceleration and propagation of energetic particles in many astrophysical systems where relativistic outflows are the main drivers of the emission, such as AGNs and galactic binary systems. In this paper the main results of the H.E.S.S. observations of these objects will be reviewed, and the general picture that emerges from them will be presented. We will also comment on prospects for future investigations with H.E.S.S.-II.


2014 ◽  
Vol 788 (2) ◽  
pp. 165 ◽  
Author(s):  
K. Hada ◽  
M. Giroletti ◽  
M. Kino ◽  
G. Giovannini ◽  
F. D'Ammando ◽  
...  

2008 ◽  
Author(s):  
Diego F. Torres ◽  
Felix A. Aharonian ◽  
Werner Hofmann ◽  
Frank Rieger

2011 ◽  
Author(s):  
Julian Sitarek ◽  
Fabio Zandanel ◽  
Francisco Prada ◽  
Saverio Lombardi ◽  
Andrii Neronov ◽  
...  

1985 ◽  
Vol 115 (1) ◽  
pp. 163-183 ◽  
Author(s):  
S. K. Gupta ◽  
P. V. Ramana Murthy ◽  
S. C. Tonwar ◽  
P. R. Vishwanath

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