Analysis of the Ground Based Data for 3C279: 1990-1999
S. D. Bloom, A. E. Wehrle
T. J. Balonek
H. Teräsranta, M. Tornikoski
M. F. Aller, H. D. Aller
D. J. Thompson
We consider the multi-waveband light curves for the blazar 3C 279 during
1990-1999. Overall, a growth of a long term outburst from 1990 to the present
is apparent from 4.8-37 GHz, with an amplitude roughly between a factor of 2-3
gain in flux, depending on frequency. This long term behavior is ambiguous
at higher frequencies, probably due to undersampling.
After subtraction of exponential functions which
are fit to the minima of the short term flares, we see that the amplitudes
of these short term flares (at 22 and 37 GHz) match the shape of the gamma-ray
light curve of the EGRET instrument on the Compton Gamma-Ray Observatory
(CGRO). The ratio of the fluxes from the succesive peaks in millimeter
similar to that of the ratio of fluxes from the succesive gamma-ray peaks for similar time spans; however,the time delays of millimeter or optical and gamma-ray flares are difficult to establish due to the paucity
of gamma-ray observations. The R-Band optical light curve
does not show the same structure as the millimeter light curves.
To quantify these results further, we have calculated the
Discrete Correlation Functions (DCF's) for the
radio, millimeter, and optical data of 3C 279 during the last decade (mostly co
incident with the CGRO/EGRET
mission). We have used this technique before and after the subtraction of
exponential functions. As expected, the data closest in frequency show
moderate to strong correlations with time lags of -150 to 150 days.
However, the optical data are not correlated with
the radio or millimeter data. The most likely explanation is
that the optical emission (especially during flares) comes from a much
smaller scale component than the total source contributing to the
radio-millimeter flux. This effect is further mitigated by the
much shorter outburst timescales expected for higher frequencies,
under the assumption that the radio-optical spectrum is explained
by the synchrotron process.
File translated from TEX by TTH, version 2.32.
On 16 Jul 1999, 09:19.