Long term Ultra-Violet Variability of Seyfert galaxies

Flux variability is one of the defining characteristics of Seyfert galaxies, a class of active galactic nuclei (AGN). Though these variations are observed over a wide range of wavelengths, results on their flux variability characteristics in the ultra-violet (UV) band are very limited. We present here the long term UV flux variability characteristics of a sample of fourteen Seyfert galaxies using data from the International Ultraviolet Explorer acquired between 1978 and 1995. We found that all the sources showed flux variations with no statistically significant difference in the amplitude of UV flux variation between shorter and longer wavelengths. Also, the flux variations between different near-UV (NUV, 1850 - 3300 A) and far-UV (FUV, 1150 - 2000 A) passbands in the rest frames of the objects are correlated with no time lag. The data show indications of (i) a mild negative correlation of UV variability with bolometric luminosity and (ii) weak positive correlation between UV variability and black hole mass. At FUV, about 50% of the sources show a strong correlation between spectral indices and flux variations with a hardening when brightening behaviour, while for the remaining sources the correlation is moderate. In NUV, the sources do show a harder when brighter trend, however, the correlation is either weak or moderate.Comment: Accepted by Journal of Astrophysics and Astronom

The Soviets and the individual

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The national question and Leninism

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Stalin on the new Soviet constitution

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Speech delivered by J.V. Stalin at a meeting of voters of the Stalin Electoral Area of Moscow, February 9, 1946

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Interviews with foreign workers\u27 delegations:

https://stars.library.ucf.edu/prism/1419/thumbnail.jp

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https://stars.library.ucf.edu/prism/1395/thumbnail.jp

Stalin\u27s speeches on the American Communist party

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Marxism vs. liberalism: An interview [between] Joseph Stalin [and] H. G. Wells

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From socialism to communism in the Soviet Union: Report on the work of the Central Committee to the Eighteenth Congress of the C.P.S.U.(B.) delivered March 10, 1939

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