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Title: SPITZER OBSERVATIONS OF HOTSPOTS IN RADIO LOBES

Abstract

We have carried out a systematic search with Spitzer Warm Mission and archival data for infrared emission from the hotspots in radio lobes that have been described by Hardcastle et al. These hotspots have been detected with both radio and X-ray observations, but an observation at an intermediate frequency in the infrared can be critical to distinguish between competing models for particle acceleration and radiation processes in these objects. Between the archival and warm mission data, we report detections of 18 hotspots; the archival data generally include detections at all four IRAC bands, the Warm Mission data only at 3.6 {mu}m. Using a theoretical formalism adopted from Godfrey et al., we fit both archival and warm mission spectral energy distributions (SEDs)-including radio, X-ray, and optical data from Hardcastle as well as the Spitzer data-with a synchrotron self-Compton (SSC) model, in which the X-rays are produced by Compton scattering of the radio frequency photons by the energetic electrons which radiate them. With one exception, an SSC model requires that the magnetic field be less or much less than the equipartition value which minimizes total energy and has comparable amounts of energy in the magnetic field and in the energetic particles. Thismore » conclusion agrees with those of comparable recent studies of hotspots, and with the analysis presented by Hardcastle et al. We also show that the infrared data rule out the simplest synchrotron-only models for the SEDs. We briefly discuss the implications of these results and of alternate interpretations of the data.« less

Authors:
; ; ; ; ; ;  [1]
  1. Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22086418
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 759; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTRONOMY; ASTROPHYSICS; COMPTON EFFECT; COSMIC PHOTONS; ENERGY SPECTRA; INFRARED SPECTRA; MAGNETIC FIELDS; PHOTON EMISSION; RADIATION DETECTION; RADIOWAVE RADIATION; TAIL ELECTRONS; X RADIATION; X-RAY SPECTRA

Citation Formats

Werner, Michael W., Murphy, David W., Livingston, John H., Gorjian, Varoujan, Jones, Dayton L., Meier, David L., and Lawrence, Charles R. SPITZER OBSERVATIONS OF HOTSPOTS IN RADIO LOBES. United States: N. p., 2012. Web. doi:10.1088/0004-637X/759/2/86.
Werner, Michael W., Murphy, David W., Livingston, John H., Gorjian, Varoujan, Jones, Dayton L., Meier, David L., & Lawrence, Charles R. SPITZER OBSERVATIONS OF HOTSPOTS IN RADIO LOBES. United States. doi:10.1088/0004-637X/759/2/86.
Werner, Michael W., Murphy, David W., Livingston, John H., Gorjian, Varoujan, Jones, Dayton L., Meier, David L., and Lawrence, Charles R. Sat . "SPITZER OBSERVATIONS OF HOTSPOTS IN RADIO LOBES". United States. doi:10.1088/0004-637X/759/2/86.
@article{osti_22086418,
title = {SPITZER OBSERVATIONS OF HOTSPOTS IN RADIO LOBES},
author = {Werner, Michael W. and Murphy, David W. and Livingston, John H. and Gorjian, Varoujan and Jones, Dayton L. and Meier, David L. and Lawrence, Charles R.},
abstractNote = {We have carried out a systematic search with Spitzer Warm Mission and archival data for infrared emission from the hotspots in radio lobes that have been described by Hardcastle et al. These hotspots have been detected with both radio and X-ray observations, but an observation at an intermediate frequency in the infrared can be critical to distinguish between competing models for particle acceleration and radiation processes in these objects. Between the archival and warm mission data, we report detections of 18 hotspots; the archival data generally include detections at all four IRAC bands, the Warm Mission data only at 3.6 {mu}m. Using a theoretical formalism adopted from Godfrey et al., we fit both archival and warm mission spectral energy distributions (SEDs)-including radio, X-ray, and optical data from Hardcastle as well as the Spitzer data-with a synchrotron self-Compton (SSC) model, in which the X-rays are produced by Compton scattering of the radio frequency photons by the energetic electrons which radiate them. With one exception, an SSC model requires that the magnetic field be less or much less than the equipartition value which minimizes total energy and has comparable amounts of energy in the magnetic field and in the energetic particles. This conclusion agrees with those of comparable recent studies of hotspots, and with the analysis presented by Hardcastle et al. We also show that the infrared data rule out the simplest synchrotron-only models for the SEDs. We briefly discuss the implications of these results and of alternate interpretations of the data.},
doi = {10.1088/0004-637X/759/2/86},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 759,
place = {United States},
year = {2012},
month = {11}
}