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The Near-IR-Optical-UV Emission of BL Lacertae Objects

E. Pian·R. Falomo·R. Scarpa·A. Treves
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Abstract

Near--infrared, optical and ultraviolet quasi--simultaneous observations of 11 BL Lacertae objects are reported. For all but one source the dereddened spectral flux distribution in the $8\cdot10^{13}-2\cdot10^{15}$ Hz frequency range can be described by a single power law f$_ν\propto ν^{-α}$ with average spectral index $<α>$ = 0.88 $\pm$ 0.42 (standard deviation) plus, where relevant, the contribution of the host galaxy. In most cases the non simultaneous soft X--ray fluxes obtained by the {\it Einstein Observatory} lie on or below the extrapolation of the power law. The results are compared with the average spectral properties of other samples of BL Lacs studied separately in the IR--optical and in the UV bands. The implications for existing models of the objects are shortly discussed.

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E. Pian, R. Falomo, R. Scarpa, A. Treves. 1994-03-08. The Near-IR-Optical-UV Emission of BL Lacertae Objects. https://doi.org/10.1086/174592

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