Geodetic VLBI Observations of EGRET Blazars
| Autor: | Kerry A. Kingham, B. Glenn Piner |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Physics
education.field_of_study Superluminal motion Observational error biology Astrophysics (astro-ph) Population FOS: Physical sciences Astronomy and Astrophysics Quasar Astrophysics biology.organism_classification symbols.namesake Space and Planetary Science Very-long-baseline interferometry symbols Egret education Blazar Doppler effect |
| Zdroj: | The Astrophysical Journal. 507:706-725 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/306346 |
| Popis: | We present VLBI observations of the EGRET quasars 0202+149, CTA 26, and 1606+106, as well as additional analysis of VLBI observations of 1156+295 presented in Piner & Kingham (1997b). We have produced 8 and 2 GHz VLBI images at 11 epochs, 8 epochs, and 12 epochs, spanning the years 1989 to 1996, of 0202+149, CTA 26, and 1606+106 respectively. The VLBI data have been taken from the Washington VLBI correlator's geodetic database. We have measured the apparent velocities of the jet components and find that CTA 26 and 1606+106 are superluminal sources, with average apparent speeds of 8.9 and 2.9 h^{-1}c respectively (H_{0}=100h km s^{-1} Mpc^{-1}, q_{0}=0.5). The components in 0202+149 are stationary, and we identify this source as a compact F double. These sources all have apparently bent jets, and we detected non-radial motion of components in CTA 26 and 1156+295. We have not yet detected any components emerging subsequent to the gamma-ray flares in CTA 26, 1156+295, and 1606+106, and we derive lower limits on the ejection times of any such components. The misalignment angle distribution of the EGRET sources is compared to the distribution for blazars as a whole, and we find that EGRET sources belong preferentially to neither the aligned nor the misaligned population. We also compare the average values for the apparent velocities and Doppler beaming factors for the EGRET and non-EGRET blazars, and find no significant differences. We thus find no indication, within the measurement errors, that EGRET blazars are any more strongly beamed than their counterparts which have not been detected in gamma-rays. 47 pages, including 13 figures; accepted for publication in the Astrophysical Journal |
| Databáze: | OpenAIRE |
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