Abstract
An analysis of the data that have recently become available from observing campaigns, including VLA, VLBA, and satellite instruments, shows some remarkable similarities and significant differences in the data from some epochs of galactic microquasars, including GRS 1915+105, the concurrent radio and X-ray data [3] on Centaurus A (NGC 5128), 3C120 [35], and 3C454.3 as reported by Bonning et al. [16], which showed the first results from the Fermi Space Telescope for the concurrent variability at optical, UV, IR, and g-ray variability of that source. In combination with observations from microquasars and quasars from the MOJAVE Collaboration [32], these data provide time-dependent evolutions of radio data at mas (i.e., parsec for AGNs, and Astronomical Unit scales for microquasars). These sources all show a remarkable richness of patterns of variability for astrophysical jets across the entire electromagnetic spectrum. It is likely that these patterns of variability arise from the complex structures through which the jets propagate, but it is also possible that the jets constitution, initial energy, and collimation have significant observational consequences. On the other hand, Ulrich et al. [42] suggest that this picture is complicated for radio-quiet AGN by the presence of significant emission from accretion disks in those sources. Consistent with the jet-ambient-medium hypothesis, the observed concurrent radio and X-ray variability of Centaurus A [3] could have been caused by the launch of a jet element from Cen A’s central source and that jet’s interaction with the interstellar medium in the core region of that galaxy.
Highlights
We have become aware that jets are ubiquitous phenomena in astrophysics
Current theories suppose that the jet is formed and accelerated in the accretion disk. Even if this is true in all sources, it is still unclear whether or not astrophysical jets with shorter propagation lengths are essentially different in constitution from those that have much longer ranges, or whether the material through which the jet propagates determines the extent of the observational structures we call jets
Hannikainen [25] and Chaty [17] have discussed some of the emission characteristics of microquasars, and Paredes [38] has considered the role of microquasars and AGNs as sources of high energy γ-ray emission
Summary
We have become aware that jets are ubiquitous phenomena in astrophysics. Extended linear structures that can be associated with jets are found in starforming regions, in compact binaries, and in AGN. The early reports of the concurrent radio and X-ray variability of Centaurus A can be plausibly interpreted as the launch of a jet from Cen A’s central source into the complex structures in its core. These observations are remarkably similar to the observations of galactic microquasars and AGNs, including the observations from the Fermi Space Telescope of concurrent γ-ray, IR, Optical, and UV variability of 3C454.3 [16], and observations [33] for BL Lac, among others. This behavior is evident in the observations of Sco X-1 by Fomalont, Geldzahler, and Bradshaw [21], as discussed below, but on much shorter physical and temporal scales
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