Back to Search Start Over

Fermi-LAT Detection of Gravitational Lens Delayed Gamma-ray Flares from Blazar B0218+357

Authors :
Cheung, C. C.
Larsson, S.
Scargle, J. D.
Amin, M. A.
Blandford, R. D.
Bulmash, D.
Chiang, J.
Ciprini, S.
Corbet, R. H. D.
Falco, E. E.
Marshall, P. J.
Wood, D. L.
Ajello, M.
Bastieri, D.
Chekhtman, A.
D'Ammando, F.
Giroletti, M.
Grove, J. E.
Lott, B.
Ojha, R.
Orienti, M.
Perkins, J. S.
Razzano, M.
Smith, A. W.
Thompson, D. J.
Wood, K. S.
Publication Year :
2014

Abstract

Using data from the Fermi Large Area Telescope (LAT), we report the first clear gamma-ray measurement of a delay between flares from the gravitationally lensed images of a blazar. The delay was detected in B0218+357, a known double-image lensed system, during a period of enhanced gamma-ray activity with peak fluxes consistently observed to reach >20-50 times its previous average flux. An auto-correlation function analysis identified a delay in the gamma-ray data of 11.46 +/- 0.16 days (1 sigma) that is ~1 day greater than previous radio measurements. Considering that it is beyond the capabilities of the LAT to spatially resolve the two images, we nevertheless decomposed individual sequences of superposing gamma-ray flares/delayed emissions. In three such ~8-10 day-long sequences within a ~4-month span, considering confusion due to overlapping flaring emission and flux measurement uncertainties, we found flux ratios consistent with ~1, thus systematically smaller than those from radio observations. During the first, best-defined flare, the delayed emission was detailed with a Fermi pointing, and we observed flux doubling timescales of ~3-6 hrs implying as well extremely compact gamma-ray emitting regions.<br />Comment: ApJL, accepted for publication, 7 pages, 4 figures

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.1401.0548
Document Type :
Working Paper
Full Text :
https://doi.org/10.1088/2041-8205/782/2/L14