http://arxiv.org/abs/1503.04780
We use archival X-ray and radio VLBA data to calculate inverse Compton Doppler factors for four high-power radio, $\gamma$-loud Flat Spectrum Radio Quasars frequently monitored by the F-GAMMA project. We explore the effect of the non-simultaneity between X-ray and radio observations by calculating Doppler factors for simultaneous and non-simultaneous observations. By comparing the newly re-calculated values from this work and archival values with variability Doppler factors, we show that simultaneous/quasi-simultaneous X-ray and radio observations can provide a reliable estimate of the true Doppler factor in blazar jets. For the particular case of PKS0528+134 we find that a time-difference of up to 1 week provides inverse Compton Doppler factor estimates consistent with the variability Doppler factor of this source at the 19% percent level. In contrast, time differences of more than 30 days between radio and X-ray observations result to discrepancies from 100% to more than a factor of 4.
I. Liodakis, A. Zezas and V. Pavlidou
Tue, 17 Mar 15
38/79
Comments: 5 pages,2 figures, comments welcome
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