Abstract
Optical spectral indices of 314 quasars are presented. They are found to cluster around α0=−0.5. These together with 73 optical spectral indices from Richstone and Schmidt form our data set. We have found that the optical spectral indices have a significant correlation with the redshifts while they have no correlation with the optical luminosities. The sharp cut-off near α0 = 1/3 claimed by Richstone and Schmidt is not seen. Instead a cut-off near α0 = 5/2 is indicated. This may be interpreted as an evidence of an optically thick synchrotron source in the Rayleigh-Jeans limit in which the emitted spectrum has an index of 5/2.
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Yu, K.N. The spectral properties of quasars. Astrophys Space Sci 134, 35–45 (1987). https://doi.org/10.1007/BF00636451
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DOI: https://doi.org/10.1007/BF00636451