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Correlated multiwavelength polarization in blazar cores

D'Arcangelo, Francesca D., Marscher, A. P., Jorstad, S. G., Smith, P. S., Larionov, V. M., Hagen Thorn, V. A., Williams, G. and Gear, Walter Kieran 2009. Correlated multiwavelength polarization in blazar cores. Presented at: American Astronomical Society 213 Meeting, Long Beach, CA, 4-8 January 2009. p. 381.

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The results of intensive multiwavelength observations of a sample of 19 blazars reveal a distinct correlation between optical/infrared emission and 43 GHz emission in the stationary core. During two ten-day campaigns in 2005 and 2006, we performed nightly polarimetry in B, V, R, I, and H wavebands, as well as imaging at 43 GHz with the VLBA at 3 epochs for each campaign. We compare polarization characteristics - and the variability of those characteristics -across wavelengths in order to establish a location for the unresolved optical emission in the resolved parsec-scale jet. In our sample of 19 blazars, we find that the majority display a comparable electric vector position angle (EVPA) in both optical emission and the 43 GHz core. The majority of our objects show EVPAs that agree within 15 degrees, with 84% showing agreement within 30 degrees. In addition, we examine the variability of EVPA, percentage polarization, and flux density across wavelengths to obtain further support for the conclusion of cospatiality. Thirteen of our 19 blazars demonstrate clear correlation in behavior, and seven of these include a substantial rotation in EVPA at all wavelengths, upwards of 90 degrees in some cases. After presenting the general results for the sample, we analyze the blazar cores in greater detail. We describe the emission from each core with the aid of modelling and simulation, utilizing the mechanisms of magnetic turbulence, velocity shear, standing conical shocks, and moving transverse shocks. We present the results of this analysis for a selection of blazars, and show preliminary results from a new intensive campaign in 2008. This work is supported by the NASA ADAP and the NSF under grant AST 04-06865

Item Type: Conference or Workshop Item (Lecture)
Date Type: Completion
Status: Unpublished
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Last Modified: 04 Jun 2017 04:10

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