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Multifrequency observations of the superluminal quasar 3C 345

Bregman, Joel N. and Elias, J. and Impey, C. D. and Matthews, K. and Neugebauer, G. and Soifer, B. T. (1986) Multifrequency observations of the superluminal quasar 3C 345. Astrophysical Journal, 301 . pp. 708-726. ISSN 0004-637X. doi:10.1086/163938.

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We have investigated the continuum properties of the superluminal quasar 3C 345 with monitoring studies at radio, optical, infrared, and X-ray frequencies as well as with simultaneous multifrequency spectra extending from the radio through the X-ray bands. Variability occurs more rapidly and with greater amplitude toward shorter wavelengths in the infrared-optical region (0.4-100 μm). Radio outbursts, which appear to follow infrared-optical outbursts by about a year, occur first at the highest frequencies, as expected from optical depth effects, although the peak flux is often reached at several frequencies at once. The beginning of outbursts as defined by millimeter measurements corresponds to the appearance of the three known "superluminal" components. An increase in the X-ray flux during 1979-1980 corresponds to increased radio flux, while the infrared flux changes in the opposite sense. The multifrequency spectra show that the nearly flat radio continuum steepens at 10^(11)-10^(12) Hz and has a power-law slope of -0.91 ± 0.04 from 350 to 20 μm that steepens to -1.40 ± 0.02 at 20 μm-1200 A. A "blue bump" is detected at rest wavelengths 4000-1500 A. The X-ray emission has a flatter slope (-0.7) than the infrared-ultraviolet continuum and lies above an extrapolation of that continuum to X-ray energies. This supports the finding from variability that the X-ray emission is not simply connected to the optical emission. Although the shape of the infrared-ultraviolet continuum is generally preserved during flux variations, slope variations occur and are most common in the ultraviolet region. Most of the total power (3 x 10^(47) ergs s ^(-1)) emerges in the submillimeter-optical region but about one-sixth of the power is emitted at X-ray and radio.

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Additional Information:© American Astronomical Society Received 1985 April 1; accepted 1985 August 20 Special thanks are extended to Mike Werner and Eric Becklin for their role in obtaining the extensive infrared data of 1983 May. These investigators and T. Roelling wish to thank the infrared group at Caltech and Palomar Observatory for their support and assistance in obtaining 1 mm observations. We also wish to thank G. Miley, P. Clegg, M. Rowan Robinson, and S. Harris for their efforts in establishing and carrying out the active galaxy-pointed observations with IRAS. R. Landau, M. Sitko, and P. S. Smith made optical data available to us prior to publication. In addition, many of the optical monitoring observations were obtained by G. H. Folsom, R. L. Hackney, K. R. Hackney, R. L. Scott, P. L. Edwards, B. Q. McGimsey, P. Gombola, and G. L. Fitzgibbons as part of an ongoing program at the University of Florida (supported by the NSF, current grant AST-8400208). H. D. Aller and M. F. Aller would like to thank the NSF for their support of the University of Michigan Radio Observatory (grant AST-8301234). C. D. Impey acknowledges the SERC for observing support and receipt of a SERC/NATO Fellowship. Financial support was provided to W. W. Wisniewski, G. H. Rieke, and M. J. Lebofsky from the NSF; B. J. Wills and D. Wills from the NSF; J. N. Bregman, A. E. Glassgold, and P. J. Huggins from NASA; J. Hackwell from the NSF; J. D. Bregman, F. C. Witteborn, and D. F. Lester from NASA; T. P. L. Roellig from NASA; G. Neugebauer from NSF; W. A. Dent, T. J. Balonek, and R. E. Barvanis NSF; W. H.-M. Ku from NASA.
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Official Citation:Multifrequency observations of the superluminal quasar 3C 345 Bregman, J. N., Glassgold, A. E., Huggins, P. J., Neugebauer, G., Soifer, B. T., Matthews, K., , Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 301, Feb. 15, 1986, p. 708-726
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74782
Deposited By: Ruth Sustaita
Deposited On:06 Mar 2017 21:10
Last Modified:11 Nov 2021 05:29

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