Astron. Astrophys. 344, 61-67 (1999)

Beaming and precession in the inner jet of 3C 273

Z. Abraham ¹ and G.E. Romero <sup>*  1,2,3

1</sup> Instituto Astronômico e Geofísico, Universidade de São Paulo, Av. M. Stefano 4200, CEP 04301-904 São Paulo, SP, Brazil
² Instituto Argentino de Radioastronomía, C.C.5, (1894) Villa Elisa, Bs. As., Argentina
³ Departamento de Física, Universidad Nacional de La Plata, C.C. 67, (1900) La Plata, Argentina

Received 22 September 1998 / Accepted 21 December 1998

Abstract

We have investigated the effects of precession in the inner jet of 3C 273 on its beaming properties and high energy emission. We have used all available VLBI data to determine the kinematic evolution of the jet. The position angles, velocities and formation epochs of different superluminal components are consistent with a precessing inner jet. The time-dependence of the Doppler factor for this jet was computed and the implications for the -ray emission are discussed. Additionally, the model, when considered along with simultaneous radio and X-ray variability observations, provides an upper bound to the possible values of the Hubble constant ( km s^-1 Mpc^-1).

Key words: galaxies: jets galaxies: quasars: individual: 3C 273 gamma rays: theory radio continuum: galaxies

* Member of CONICET

Send offprint requests to: Z. Abraham

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Contents

• 1. Introduction
• 2. The VLBI jet of 3C 273
• 3. Model fitting: a precessing inner jet
• 4. The beaming factor
  • 4.1. Beaming at radio frequencies
  • 4.2. Beaming and X-rays
  • 4.3. Beaming and -rays
• 5. Implications for the -ray emission
• 6. Comments
• 7. Summary
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 10, 1999
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