The intra-day optical monitoring of BL Lacerate object 1ES 1218+304 at its highest X-ray flux level
Abstract
We here report a monitor of the BL Lac object 1ES 1218+304 in both B- and R-bands by the GWAC-F60A telescope in eight nights, when it was triggered to be at its highest X-ray flux in history by the VERITAS Observatory and Swift follow-ups. Both ANOVA and χ2-test enable us to clearly reveal an intra-day variability in optical wavelengths in seven out of the eight nights. A bluer-when-brighter chromatic relationship has been clearly identified in five out of the eight nights, which can be well explained by the shock-in-jet model. In addition, a quasi-periodic oscillation phenomenon in both bands could be tentatively identified in the first night. A positive delay between the two bands has been revealed in three out of the eight nights, and a negative one in the other nights. The identified minimum time delay enables us to estimate the MBH = 2.8 × 107 M⊙that is invalid.
- Publication:
-
Research in Astronomy and Astrophysics
- Pub Date:
- October 2021
- DOI:
- 10.1088/1674-4527/21/8/197
- arXiv:
- arXiv:2104.00920
- Bibcode:
- 2021RAA....21..197S
- Keywords:
-
- BL Lacertae objects: general;
- BL Lacertae objects: individual (1ES1218+304);
- galaxies: active;
- method: statistical;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 4 figures