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Published May 1, 1983 | Published
Journal Article Open

Extragalactic 1 millimeter sources: Simultaneous observations at centimeter, millimeter, and visual wavelengths

Abstract

Observations simultaneously made at visual (B, V, and R) wavelengths, at 1, 1.4, and 3.4 mm and at 1.3, 2, 6, and 20 cm of 9 QSOs and BL Lac objects are reported. The range of the millimeter visual spectral index ɑ_(mv) was only 0.65-0.82, typical of optically thin synchrotron emission. This may indicate that the electrons radiating synchrotron emission in this portion of the spectrum are not subjected to large radiative losses, and therefore relativistic bulk motion with Doppler factors ~10 are required. The visual spectral index is much more broadly distributed and typically larger than ɑ_(mv). The spectral energy distributions have not changed much in the last 2-5 years except for 2251 + 15 and perhaps 0235 + 164. Only 1749 +09 shows a sharp spectral break shortward of 1 mm. Sixteen other sources were observed at 1 mm, of which seven were detected.

Additional Information

© 1983 American Astronomical Society. Received 1982 September 30; accepted 1982 October 27. We thank L. Rudnick for extensive discussion; W. Dent, E. Grossman, J. Kenney, W. Kinzel, R. Perley, J. Rodriguez, T. Roellig, and the staff of the NRAO Tucson facility for observing assistance; and Gary Grasdalen and Roger Hildebrand for attempting 10 ,urn and 400 ,urn observations. The work of E. E. E. was supported by U.S. Air Force contract no. F04701-82-C-0083. Observations at Palomar were supported by NASA. Work at Mount Lemmon and at the University of Minnesota is supported by NSF grants AST-80-15307 and AST-81-14737.

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August 22, 2023
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