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Compton scattering in a converging fluid flow - II. Radiation-dominated shock

Blandford, R. D. and Payne, D. G. (1981) Compton scattering in a converging fluid flow - II. Radiation-dominated shock. Monthly Notices of the Royal Astronomical Society, 194 (4). pp. 1041-1055. ISSN 0035-8711.

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The problem of Compton scattering in an optically thick fluid flow in which bulk motion is the dominant source of photon heating is illustrated by analysing a radiation-dominated, plane-parallel shock of speed u with photon to electron ratio greatly exceeding ∼(m_p/m_e)⁠. In traversing the shock (of thickness ∼(c/u) Thomson optical depths), a typical photon experiences (c/u)2 scatterings, each one giving a secular fractional energy increase ∼(u/c)^2 and a total average increase of order unity. In a converging fluid flow, an exponentially small number of photons are accelerated to an exponentially large energy. Thus, a power-law spectrum will be transmitted at high frequencies. For a shock of Mach number M, bulk acceleration produces a spectral index α = (M^2 − ½)(M^2 + 6)(M^2 – 1)^(−2), which tends to unity for a strong shock. The applicability of these results to quasars and the microwave background is briefly discussed.

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Blandford, R. D.0000-0002-1854-5506
Additional Information:© 1981 Royal Astronomical Society. Provided by the NASA Astrophysics Data System. Received 1980 August 20; in original form 1980 June 3. This work was supported in part by NSF grant AST78-05484. RB thanks the Director and staff of the National Radio Astronomy Observatory, Charlottesville, where part of this work was carried out, for their hospitality. We also thank D. C. Brydges for assistance with proving the identity in the Appendix and Y. Gursel and D. MacDonald for assistance with some of the numerical work.
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Issue or Number:4
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Official Citation:R. D. Blandford, D. G. Payne, Compton scattering in a converging fluid flow – II. Radiation-dominated shock, Monthly Notices of the Royal Astronomical Society, Volume 194, Issue 4, 1 April 1981, Pages 1041–1055,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95666
Deposited By: George Porter
Deposited On:23 May 2019 18:13
Last Modified:03 Oct 2019 21:15

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