Blazar OJ 287 after First VHE Activity: Tracking the Reemergence of the HBL-like Component in 2020
Abstract
We report the reemergence of a new broadband emission through a detailed and systematic study of the multiwavelength spectral and temporal behavior of OJ 287 after its first-ever reported very high energy activity in 2017 to date, which includes the second-highest X-ray flux of the source. The source shows high optical to X-ray flux variations, accompanied mainly by strong spectral changes. The optical to X-ray flux variations are correlated and simultaneous except for two durations when they are anticorrelated. The flux variations, however, are anticorrelated with the X-ray spectral state while correlated with optical-UV (ultraviolet). Weekly binned Fermi-LAT data around the duration of the highest X-ray activity show a few detections with a log-parabola model but none with a power law, yet the extracted LAT spectral energy distribution of the high-activity duration for both the models is similar and shows a hardening above 1 GeV. Further, near-infrared data indicate strong spectral change, resembling a thermal component. Overall, the combined optical to gamma-ray broadband spectrum establishes the observed variations to a new high-energy-peaked broadband emission component, similar to the one seen during the highest reported X-ray flux state of the source in 2017. The observed activities indicate some peculiar features that seem to be characteristic of this emission component, while its appearance a few years around the claimed ~12 yr optical outbursts strongly indicates a connection between the two.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2021
- DOI:
- 10.3847/1538-4357/ac19b8
- arXiv:
- arXiv:2010.14431
- Bibcode:
- 2021ApJ...921...18K
- Keywords:
-
- Blazars;
- Relativistic jets;
- High energy astrophysics;
- Active galaxies;
- Non-thermal radiation sources;
- BL Lacertae objects;
- Supermassive black holes;
- X-ray active galactic nuclei;
- 164;
- 1390;
- 739;
- 17;
- 1119;
- 158;
- 1663;
- 2035;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 14 pages, 6 figures, 1 table, ApJ (in press)