Long-term variations of total and polarized fluxes, absolute energy distribution, and line strength of BL Lac and 4 quasi-stellar sources.

Abstract

view Abstract Citations (74) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Long-term variations of total and polarized fluxes, absolute energy distribution, and line strength of BL Lacertae and four quasi-stellar sources. Visvanathan, N. Abstract Observations of blue magnitude, polarization, wavelength dependence of polarization, absolute energy distribution of the continuum, and the strength of emission lines were obtained simultaneously for the variable QSSs 3C 279, 3C 345, 3C 446, 3C 454.3, and the object BL Lacertae on several occasions during the period 1967-1970. The continuum was linearly polarized in all these objects during outburst and nonoutburst periods and also when the objects reached minimum brightness. Whenever the total flux increased, an increase in polarized flux was observed. The position angle of the electric vector changed during the burst. The ratio between the polarized flux and the total flux does not exceed the value of about 0.16. This low value is interpreted as being due to the resultant polarization caused by several active spots in the continuum emitting-region. The absolute energy distributions of the continua both in active and quiet periods show that a power4aw representation of the continuum is valid. This fact and the finding that the polarization is independent of wavelength support the view that the radiation in these objects in the observed frequency range is of synchrotron origin in both active and quiet periods. Variations in the spectral index of the continua were observed, but no simple relationship between color and brightness was found. During the period of our observations the absolute intensity of the emission line Mg ii in 3C 345 and 3C 434.3, and the C iv line in 3C 446, remained constant within 1020 percent. The emission line Mg ii in 3C 345 was unpolarized, indicating that the regions from which the emission line originates are randomly arranged. Subject headings: polarization - quasi-stellar sources or objects Publication: The Astrophysical Journal Pub Date: January 1973 DOI: 10.1086/151842 Bibcode: 1973ApJ...179....1V full text sources ADS | data products SIMBAD (1) NED (1)