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I'm reading articles about blazars, and in a discussion about models concerning Blazar SEDs (Spectral Energy Densities) there are mentions of different processes: Sychrotron scattering, inverse Compton scattering, etc.

Now concerning models for blazar emission, there are a lot of acronyms. I managed to figure out that SSC stands for "Self Synchrotron-Compton," but I have no idea what the acronyms "XC" and "BBC" stand for. And it isn't easy to google out "bbc + anything" without finding just references to... you know:

Does anyone know or have a good sense of what those acronyms might stand for?

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Can you provide a link or links to examples of these acronyms – John Rennie Jul 14 '14 at 17:13
It's actually Synchrotron Self-Compton, not Self Synchrotron-Compton. – Kyle Kanos Jul 14 '14 at 17:27
XC might be an acronym for "external Compton" but I'm reasonably certain that BBC means "Blackbody Compton." – Kyle Kanos Jul 14 '14 at 17:45
up vote 5 down vote accepted

SSC: synchrotron self-Compton

BBC: Compton upscattered blackbody radiation; Compton upscattering of stellar blackbody photons

XC: upscattering of photons emitted by the accretion flow; accretion flow photons

From: and

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I'm not sure where 'XC' comes from. I merely suspect it is not an acronym, but rather derived from $x_\text{c}$, the sonic (or critical) point distance. I may be wrong about that. – Keep these mind Jul 14 '14 at 18:20
Minor comment to the post (v1): In the future please link to abstract pages rather than pdf files, e.g., and – Qmechanic Jul 14 '14 at 18:26

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