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Far UV observations of PKS2155-304
In BL Lac objects the absence of broad emission lines may be due either to a lack of ionizing continuum or to a lack of cool gas (T ≲ 10 4 K) 1 . UV observations of BL Lac objects are interesting in that they provide a measurement of the continuum, and they include the wavelength range of Ly α , whi...
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Published in: | Nature (London) 1980-06, Vol.285 (5766), p.555-557 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | In BL Lac objects the absence of broad emission lines may be due either to a lack of ionizing continuum or to a lack of cool gas (T ≲ 10
4
K)
1
. UV observations of BL Lac objects are interesting in that they provide a measurement of the continuum, and they include the wavelength range of Ly
α
, which is in principle the most favourable line for detection. We report here several spectra of the BL Lac object PKS2155–304 in the 1,150–3,200 A band taken with the IUE when the object was in a bright phase. The UV flux connects smoothly with the optical and IR observations of the source in its brightest state and its extrapolation matches the soft X-ray flux, implying a change in spectral slope around 10
15
Hz. |
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ISSN: | 0028-0836 1476-4687 |
DOI: | 10.1038/285555a0 |