A METHOD FOR LOCALIZING ENERGY DISSIPATION IN BLAZARS USING FERMI VARIABILITY
- Department of Physics, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)
- NASA Goddard Space Flight Center, Code 660, Greenbelt, MD 20771 (United States)
The distance of a Fermi-detected blazar {gamma}-ray emission site from a supermassive black hole is a matter of active debate. Here we present a method for testing if the GeV emission of powerful blazars is produced within the subparsec-scale broad-line region (BLR) or farther out in the parsec-scale molecular torus (MT) environment. If the GeV emission takes place within the BLR, the inverse Compton (IC) scattering of the BLR ultraviolet (UV) seed photons that produces the {gamma}-rays takes place at the onset of the Klein-Nishina regime. This causes the electron cooling time to become practically energy-independent and the variation of the {gamma}-ray emission to be almost achromatic. If, on the other hand, the {gamma}-ray emission is produced farther out in the parsec-scale MT, the IC scattering of the infrared (IR) MT seed photons that produces the {gamma}-rays takes place in the Thomson regime, resulting in energy-dependent electron cooling times, manifested as faster cooling times for higher Fermi energies. We demonstrate these characteristics and discuss the applicability and limitations of our method.
- OSTI ID:
- 22078503
- Journal Information:
- Astrophysical Journal Letters, Vol. 758, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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