Speaker
Dr
Francesco de Palma
(UniSalento & INFN Lecce)
Description
QSO B0218+357 (z = 0.944±0.002 ) is currently the only gravitationally lensed source from which very-high-energy (VHE, >~100GeV) gamma-ray emission has been detected. We report the Fermi-LAT monitoring of the source between 2016 and 2020 in conjunction with multiwavelength monitoring observations in radio interferometry and in the optical, X-ray, and VHE ranges. During the monitoring, individual flares in optical, X-ray and GeV bands were observed. An observable effect of the gravitational lensing , during bright flares, is a time delay between the lensed images. Fermi-LAT detected previous flares in 2012 and 2014, allowing for a measure of the delay (~11 days) compatible with measures done in other wavelengths. Simultaneous data taken by the MAGIC telescopes allow us to search for the associated VHE emission, constraining the VHE gamma-ray duty cycle of the source, even in the absence of a significant detection. We use the X-ray data obtained with XMM to evaluate the column density of the dust in the lensing galaxy ( z = 0.68466±0.00004). We use radio interferometry measurements to model the source-lens-observer geometry and determine the magnifications and time delays for different components of the image. We model the quiescent emission in which the high-energy bump is explained as a combination of synchrotron-self-Compton and external Compton processes. The bulk of the low energy emission can be explained as originated from a region located along the jet at tens of parsecs from the central engine.
| Please choose the session this abstract belongs to | Extragalactic sources |
|---|
Primary author
Dr
Francesco de Palma
(UniSalento & INFN Lecce)
Co-authors
Dr
Alessandra Lamastra
(INAF Roma)
Ms
Anna Barnacka
(Smithsonian Astrophysical Observatory, Cambridge)
Dr
D. K. Sahu
(Indian Institute of Astrophysics, Bangalore 560034, India)
Prof.
Elina Lindfors
(University of Turku)
Dr
Filippo D'Ammando
(INAF Bologna)
Prof.
Francesco Longo
(Università di Trieste & INFN Trieste)
Dr
Julian Sitarek
(University of Lodz)
Dr
Kari Nilsson Nilsson
(University of Turku)
Dr
Kazuhiro Hada
(The Graduate University for Advanced Studies (SOKENDAI) Tokyo)
Marina Manganaro
(University of Rijeka)
Dr
Vandad Fallah Ramazani
(Ruhr-Universitat Bochum)
