Radio to X-ray Spectrum

Fig. 8 shows the broad band spectrum of the western hot spot. All of the radio points and most of the optical and near infrared ones were taken from Meisenheimer, Yates & Röser (1997). To these we added the flux densities at $\simeq$ 2900 Å and $\simeq$ 6200 Å obtained from our analysis of archival HST data (Section 2.2). These HST values may underestimate the true flux densities as some of the emission is resolved out. Also included is the original estimate of the X-ray flux density from the Einstein Observatory (Röser & Meisenheimer 1987) and the Chandra-measured intrinsic spectrum. The Einstein point is a factor of $\sim$ 2 higher than the Chandra measurement; this may be a result of partial blending of the hot spot with the much stronger nuclear source in the low spatial resolution Einstein observation. The radio spectrum of the hot spot is well described by a power law with $\alpha$ = 0.740 $\pm$ 0.015 (Meisenheimer, Yates & Röser 1997), but there must be a break or turnover in the spectrum at 10$^{13-14}$ Hz to accommodate the near infrared and optical measurements. It is also apparent that the X-ray spectrum is not a simple extension of the radio and optical measurements to higher frequencies. The luminosities of the radio to optical and the X-ray components are given in Tab. 3.