Open AccessRXTE observations of 3C 279 during a high‐energy flare
Author(s) -
Lawson A. J.,
M I. M.,
Marscher A. P.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02563.x
Subject(s) - flare , physics , astrophysics , blazar , light curve , flux (metallurgy) , solar flare , exponential decay , spectral index , gamma ray , astronomy , spectral line , nuclear physics , materials science , metallurgy
We present details of a large X‐ray flare in the blazar 3C 279 detected during a 3‐week period of daily observations by the satellite RXTE in early 1996. The flare lasted for a total of 7 d. The shape of the flare is well described by a symmetrical, exponential rise and fall with e‐folding time‐scales in each case of 1.1 d. The peak measured flux is three times the quiescent level. The flare is superimposed on a well‐defined quiescent level and appears to represent a separate emission component. There is no statistically significant variability of the X‐ray spectral index during the observations, but the errors are large and the data hint at a hardening of about 0.1 at the peak of the flare. Such a hardening is required to allow the X‐ray flare spectrum to join on, in a single power law, to the γ‐ray flare that occurred at the same time. The exponential rise and decay most likely correspond to a variation in the acceleration of relativistic electrons or in the flux of seed photons, if the latter do not originate in the jet, as the energy loss time‐scales are shorter than the rise and decay time‐scales and the flare profile does not match that expected if light‐travel delays determine the light curve.