Variability of two BL Lacertae objects: J2005+77 and J2022+76 Sotnikova Yu.V., Erkenov A.K .

1. Variability of two BL Lacertae objects: J2005+77 and J2022+76 Sotnikova Yu.V., Erkenov A.K. Special Astrophysical ObservatoryRussian Academy of Sciences

2. Review • the model of interstellar scintillations [Rickett et al. 1995, Walker 1998 ] • the shock model [Qian et al. 1996a, Spada et al. 1999 ] • the gravitational microlensing [Wagner and Witzel 1995] • the coherent emission[Benford & Lesch 1998]

3. OBSERVATIONS Sources were observed at RATAN-600 at 6 frequencies (21.7, 11.2, 7.7, 4.8, 2.3 and 1.1 GHz) during the period 1999-2008 and also in August 2007 during 30 days daily. J2005+77 and J2022+76 – BL Lacertae was studied repeatedly to find fast variability [Peng et al 2000; Quirrenbach et al. 2000; Kraus et al. 2003]; source shows mostly slow variations (days and more) has never studied to find fast variability • 1997 - J2005+77 was observed during three-week campaign with • Infrared Space Observatory (ISO, at 100 μm) spacecraft; • VLA (1.3, 2, 3.6, 6 and 20 cm); • Effelsberg (7 mm, 1.3, 2.8 and 6 cm); • optical telescopes in Heidelberg (0.7 m) and on Calar Alto (1.2 m) in Spain. As a result radio data shows a variability of ~ 5%, the IR data of ~ 20%, and the optical data of ~ 50%.

4. modulation index variability amplitude J2007+77 Z=0.342

5. The radio, IR and optical spectrum of 2005+77 turnover frequency break frequency Radio, IR to optical spectrum of 2007+77 [Peng B., Kraus A. et al 2000] A multi-component core-jet structure in 2007+77 at 5 GHz observed by VSOP in April 1998 [Jin et al. 1999]

6. Compact structure of 2005+77, VLBI, 1999, 2001, 2005 and 2006 at 15.3 and 8.6 GHz [http://lacerta.gsfc.nasa.gov/vlbi/images/]

7. Radiospectra of 2007+77 at several epochs (RATAN-600)

8. Red shift of the source was not determined, but it is supposed that Z > 0.2[Stickel & Kurh 1996] Correlation coefficient: 0.7 (at 2.7 and 3.9 cm); 0.6 (at 3.9 and 6.3 cm) Variability amplitude is 3.13% – 4.56% – 4.60% (at 11.2, 7.7 and 4.8 GHz accordingly) J2022+76 Z=? Radiospectra of 2022+76 at several epochs (RATAN-600)

9. Compilation radiospectra of 2022+76 from data base CATS (http://www.sao.ru/cats/) Compact structure of 2022+76, VLBI, 1995 and 2006[http://lacerta.gsfc.nasa.gov/vlbi/images/]

10. J2005+77 Z=0.342 J2022+76 Z > 0.2 Possiblereasons… • Shock propagation (variability amplitude increases with frequency)Interstellar scattering (~0.6 mas)Gravitational microlensing - background galaxy Z=0.165, - projection of its distant 30´´ • Shock propagation Interstellar scattering (variability amplitude increases with decreasing of frequency; the maximum variability amplitude must be near the frequency 5 GHz)Gravitational microlensing- Z isn’t known;- Z of background source isn’t vvvknown, - projection of its distant is 7´´ • [M. Stickel , A&A, 1996]

11. ConclusionsVarious characters of variability of sources are analyzed and simple arguments are adduced in favor of preferable mechanisms of emission generation in each object under study.1.The source J2005+77 is probably a typical representative of AGNs with jet activity.2. For the source J2022+76 a correlation of emission alterations at different frequencies could point both to internal reason of variations and to external reason. The behavior of variability amplitude could point to the interstellar scattering. The absence of a measured red shift and experimental information in other wavelength ranges does not allow us interpreting unambiguously the obtained observational data.

12. The time scale J2005+77 3.5 and 6 days - 1.3 cm 2 days - 2 cm 2.5 days - 3.6 and 6 cm IR-regime - 2, 4 and 6 days Optical - 4 days

13. D=41 from data of study 1997 θ ~ 0.6 mas – diameter of the variable component

16. Light curves of antenna temperature of J2005+77 at the frequencies 4.8, 7.7 and 11.2 GHz