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Particle acceleration and magnetic field structure in PKS2155-304: optical polarimetric observations

Barres de Almeida, U.; Ward, M.J.; Dominici, T.P.; Abraham, Z.; Franco, G.A.P.; Daniel, M.K.; Chadwick, P.M.; Boisson, C.


U. Barres de Almeida

M.J. Ward

T.P. Dominici

Z. Abraham

G.A.P. Franco

M.K. Daniel

C. Boisson


In this paper, we present multiband optical polarimetric observations of the very-high energy blazar PKS 2155−304 made simultaneously with a HESS/Fermi high-energy campaign in 2008, when the source was found to be in a low state. The intense daily coverage of the data set allowed us to study in detail the temporal evolution of the emission, and we found that the particle acceleration time-scales are decoupled from the changes in the polarimetric properties of the source. We present a model in which the optical polarimetric emission originates at the polarized mm-wave core and propose an explanation for the lack of correlation between the photometric and polarimetric fluxes. The optical emission is consistent with an inhomogeneous synchrotron source in which the large-scale field is locally organized by a shock in which particle acceleration takes place. Finally, we use these optical polarimetric observations of PKS 2155−304 at a low state to propose an origin for the quiescent gamma-ray flux of the object, in an attempt to provide clues for the source of its recently established persistent TeV emission.

Journal Article Type Article
Publication Date Nov 1, 2010
Deposit Date Oct 20, 2011
Publicly Available Date Jan 4, 2013
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 408
Issue 3
Pages 1778-1787
Keywords Polarization, BL Lacertae objects, PKS 2155−304, Jets.
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