An explanation of abrupt infrared cutoffs of extragalactic radio sources by shock accelerated particles including self-generated turbulence
- Joint Institute for Laboratory Astrophysics, Boulder, CO (USA)
High-frequency cutoffs in the infrared synchrotron spectra of several extragalactic radio sources (including hot spots) require relativistic particle distributions with power-law behavior for low momenta and a nearly ideal sharp cutoff at a certain high momentum. The recent photometry of some hotspots provides an ideal opportunity to test theoretical models. So far, model spectra obtained by applying a first-order Fermi model and using a constant or variable spatial diffusion coefficient failed to match the steep cutoffs althoguh they reproduce other features of the observed spectra. However, taking into account the self-generated turbulence by the relativistic particles on the upstream side of the shock completely changes the spectral behavior near the cutoff and leads to extraordinarily good fits to observed data. It turns out that the upstream side plays the major role in determining the shape of the cutoff. Applying a simple plane and parallel geometry of magnetic field and plasma velocity, the transport equation is solved numerically and the results are presented depending on one parameter, the background level of turbulence. Some important physical parameters can be derived and expressed in terms of observable quantities. 24 refs.
- OSTI ID:
- 7058707
- Journal Information:
- Astrophysical Journal; (USA), Vol. 347; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
COSMIC RADIO SOURCES
INFRARED SPECTRA
ACCELERATION
DIFFUSION
MATHEMATICAL MODELS
PHOTOMETRY
RELATIVISTIC RANGE
SHOCK WAVES
SYNCHROTRON RADIATION
TRANSPORT THEORY
TURBULENCE
BREMSSTRAHLUNG
ELECTROMAGNETIC RADIATION
ENERGY RANGE
RADIATIONS
SPECTRA
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources