Study of Large Scale Jet in M87 at the Multi-Wavebands

The large scale jet of the radio galaxy M87 has been observed in high resolution at radio and opt ical wavelengths as well as X-ray band, the spectra of the knots are commonly believed to be generated from synchrotron emission. We study spectra of the knots in the jet at the multi-wavebands by using Kardashev-Packolczyk radiation model, and obtain the corresponding Doppler factor. Combined with superluminal motion, we derive the Lorentz factor and the angle to the line of sight for individual knots. Our results show that M87 has a slightly bend as well as a moderated relativistic jet. We also find that the bulk velocity of its jet decelerates as it flows down.