Open AccessBulk motion of ultrarelativistic conical blazar jets
Author(s) -
Wiita Paul J.,
Dhurde Samir
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10376.x
Subject(s) - physics , blazar , very long baseline interferometry , lorentz factor , astrophysics , conical surface , jet (fluid) , lorentz transformation , flux (metallurgy) , geometry , classical mechanics , mechanics , gamma ray , mathematics , materials science , metallurgy
Allowing for the conical shape of ultrarelativistic blazar jets with opening angles of a few degrees on parsec‐scales, we show that their bulk Lorentz factors and viewing angles can be much larger than the values usually inferred by combining their flux‐variability and proper‐motion measurements. This is in accord with our earlier finding that such ultrarelativistic (Lorentz factor, Γ > 30 ) conical jets can reconcile the relatively slow apparent motions of Very Long Baseline Interferometry (VLBI) knots in TeV blazars with the extremely fast flows implied by their rapid γ‐ray variability. This jet geometry also implies that de‐projected jet opening angles will typically be significantly underestimated from VLBI measurements. In addition, de‐projected jet lengths will be considerably overestimated if high Lorentz factors and significant opening angles are not taken into account.