Correlation Analysis of Delays between Variations of Gamma-Ray and Optical Light Curves of Blazars
Abstract
:1. Introduction
2. Results
3. Method
- Each object’s active periods are identified based on the light curve behavior (details can be found in [11]).
- Most -ray active periods with fluxes exceeding + 3 are re-reduced, allowing the photon index to vary and binning on a shorter time interval. Optical data are binned into 1-day periods.
- For each source, the ZDCF is calculated for the entire time span of observations and for each active period.
- Each ALC is built by randomly selecting and randomly placing active periods, preserving the observational dates by either using the closest observed point, if within 7 days, or interpolating the data.
- After the active periods have been placed in the ALC, the remaining observational fluxes are randomly selected and randomly placed on the remaining observational dates.
- The ALCs are randomly paired and sent through the ZDCF for analysis.
- Results of the ZDCF analysis of ALCs are used to derive 1-, 2-, and 3-σ probabilities to obtain a given coefficient of correlation by chance.
4. Summary
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
MDPI | Multidisciplinary Digital Publishing Institute |
DOAJ | Directory of open access journals |
ZDCF | z-transformed discrete correlation function |
ALC | artificial light curves |
OC | Overall Correlation |
CIC | Consistent Individual Correlation |
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Symbol | Telescope | |||
---|---|---|---|---|
Shape | Color | Observatory (Telescope or Monitoring Program) and Location | Diameter | Wavebands |
Space-based | ||||
⋄ | black | Fermi Gamma Ray Space Telescope (LAT) | -ray (0.1 GeV–200 GeV) | |
Ground-based | ||||
× | indigo | Lowell Observatory (Perkins Telescope), Flagstaff, Arizona | 1.83 m | B, V, R, I |
◃ | light blue | Crimean Astrophysical Observatory (AZT-8) | 0.70 m | B, V, R, I |
▿ | green | Observatorio del Roque de los Muchachos | 2.00 m | R |
(Liverpool Telescope), La Palma, Spain | ||||
orange | Calar Alto Observatory (MAPCAT), Andalucía, Spain | 2.20 m | R | |
□ | blue | Cerro Tololo Inter-American Observatory (SMARTS), | 0.90–1.50 m | B, V, R, J, K |
Cerro Tololo, Chile | ||||
▹ | red | St. Petersburg University (LX-200), St. Petersburg, Russia | 0.40 m | B, V, R, I |
Consistent Individual Correlations: | Consistent Individual Correlations: | |||
---|---|---|---|---|
−−Yes −− | −−No −− | |||
BL Lac | FSRQ | BL Lac | FSRQ | |
Overall Correlation: Yes | 0716+714 (-1) | 1633+382 (0) | 0235+164 (-6) | 0336-019 (-10) |
BL Lac (-1) | 1730-130 (2) | 0954+658 (-1) | 0420-014 (-12) | |
CTA102 (0) | 1219+285 (-11) | 0827+243 (-22) | ||
3C454.3 (0) | 1749+096 (0) | 1222+216 (-23) | ||
Mkn421 (-13) | 1622-297 (+1) | |||
3C279 (-43) | ||||
Overall Correlation: No | OJ287 (-1) | 0735+178 | 0836+710 | |
0829+046 | 1156+295 | |||
1055+018 | 1308+326 | |||
Mkn501 | 1510-089 | |||
3C66A | 3C273 | |||
3C345 |
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Williamson, K.E.; Jorstad, S.G.; Marscher, A.P.; Larionov, V.M.; Agudo, I.; Arkharov, A.A.; Blinov, D.A.; Casadio, C.; Gómez, J.L.; Hagen-Thorn, V.A.; et al. Correlation Analysis of Delays between Variations of Gamma-Ray and Optical Light Curves of Blazars. Galaxies 2016, 4, 64. https://doi.org/10.3390/galaxies4040064
Williamson KE, Jorstad SG, Marscher AP, Larionov VM, Agudo I, Arkharov AA, Blinov DA, Casadio C, Gómez JL, Hagen-Thorn VA, et al. Correlation Analysis of Delays between Variations of Gamma-Ray and Optical Light Curves of Blazars. Galaxies. 2016; 4(4):64. https://doi.org/10.3390/galaxies4040064
Chicago/Turabian StyleWilliamson, Karen E., Svetlana G. Jorstad, Alan P. Marscher, Valeri M. Larionov, Iván Agudo, Arkady A. Arkharov, Dmitry A. Blinov, Carolina Casadio, José L. Gómez, Vladimir A. Hagen-Thorn, and et al. 2016. "Correlation Analysis of Delays between Variations of Gamma-Ray and Optical Light Curves of Blazars" Galaxies 4, no. 4: 64. https://doi.org/10.3390/galaxies4040064