Study of Time Varitions of UV Continuum and Emission Lines in 3C 390.3
Abstract
Based on the IUE SWP spectra obtained between 1978 and 1994, the variations of the UV continuum and the Lyα and C IV emission lines of the broad-line radio galaxy 3C 390.3 are studied. The UV continuum between 1220 and 1990 A has varied considerably. In 1991 August, the flux at 1360 A reached a maximum level of 1.3 x 10^14^ erg cm^-2^ s^-1^ A^-1^, 27 times as high as its minimum level. At 1850 A, the continuum varies by a factor of ~12. Significant variations are frequently observed in periods as short as one month. The total flux of Lyα and C IV emission varies by a factor of ~5. Their profiles are fitted with one narrow component, unresolved at the instrumental resolution of FWHM ~ 2000 km s^-1^, and three broad components (FWHM ~ 6000 km s^-1^). The narrow component varies by a factor of ~2.5. The broad components on the blue and red wings of the Lyα and C IV emission profile, which correspond to the double bumps in the Hα and Hβ emission feature, display a close correlation to the varying continuum, with a time lag of ~45 days. The blue Lyα component has been stronger than the red component except for several epochs in 1980 and 1991. The C IV/Lyα flux ratio is -0.4 for the narrow component. For the broad components, this ratio varies considerably around an average value of unity. In 1991 March, the blue Lyα component was stronger than the red, while for C IV the red component was stronger. Such differential variations do not match the accretion disk characteristics. The findings suggest that the narrow- and broad-line region in 3C 390.3 may be associated with a radio jet.
- Publication:
-
The Astronomical Journal
- Pub Date:
- April 1996
- DOI:
- 10.1086/117891
- arXiv:
- arXiv:astro-ph/9603008
- Bibcode:
- 1996AJ....111.1498Z
- Keywords:
-
- GALAXIES: INDIVIDUAL: 3C 390.3;
- GALAXIES: ACTIVE;
- ULTRAVIOLET: GALAXIES;
- Astrophysics
- E-Print:
- To appear in The Astronomical Journal, April issue. 24 pages