The ever-surprising blazar OJ 287: multiwavelength study and appearance of a new component in X-rays

Author(s):Show less -

Kushwaha, Pankaj ^[1] ; Gupta, Alok C. ^{[2, 3]} ; Wiita, Paul J. ^[4] ; Pal, Main ^[5] ; Gaur, Haritma ^[2] ; de Gouveia Dal Pino, E. M. ^[1] ; Kurtanidze, O. M. ^{[6, 7, 8, 9]} ; Semkov, E. ^{[10, 11]} ; Damljanovic, G. ^[12] ; Hu, S. M. ^[13] ; Uemura, M. ^[14] ; Vince, O. ^[12] ; Darriba, A. ^{[15, 16]} ; Gu, M. F. ^[3] ; Bachev, R. ^{[10, 11]} ; Chen, Xu ^[13] ; Itoh, R. ^[17] ; Kawabata, M. ^[14] ; Kurtanidze, S. O. ^[8] ; Nakaoka, T. ^[14] ; Nikolashvili, M. G. ^[8] ; Sigua, L. A. ^[8] ; Strigachev, A. ^{[10, 11]} ; Zhang, Z. ^[18]

Affiliation:Show less -

^[1] Univ Sao Paulo, Dept Astron IAG USP, BR-05508090 Sao Paulo - Brazil

^[2] Aryabhatta Res Inst Observat Sci ARIES, Manora Peak 263002, Nainital - India

^[3] Chinese Acad Sci, Shanghai Astron Observ, Key Lab Res Galaxies & Cosmol, 80 Nandan Rd, Shanghai 200030 - Peoples R China

^[4] Coll New Jersey, Dept Phys, POB 7718, Ewing, NJ 08628 - USA

^[5] Astron & Astrophys Div, Phys Res Lab, Ahmadabad 380009, Gujarat - India

^[6] Kazan Fed Univ, Engelhardt Astron Observ, Tatarstan 420008 - Russia

^[7] Guangzhou Univ, Ctr Astrophys, Guangzhou 510006, Guangdong - Peoples R China

^[8] Abastumani Observ, Abastumani 0301 - Rep of Georgia

^[9] Chinese Acad Sci, Natl Astron Observat, Key Lab Opt Astron, Beijing 100012 - Peoples R China

^[10] Bulgarian Acad Sci, Inst Astron, 72 Tsarigradsko Shosse Blvd, BU-1784 Sofia - Bulgaria

^[11] Bulgarian Acad Sci, Natl Astron Observ, 72 Tsarigradsko Shosse Blvd, BU-1784 Sofia - Bulgaria

^[12] Astron Observ, Volgina 7, Belgrade 11060 - Serbia

^[13] Shandong Univ, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Inst Space Sci, Weihai 264209 - Peoples R China

^[14] Hiroshima Univ, Hiroshima Astrophys Sci Ctr, Kagamiyama 1-3-1, Higashihiroshima 7398526 - Japan

^[15] Amer Assoc Variable Star Observers, 49 Bay State Rd, Cambridge, MA 02138 - USA

^[16] Group M1, Ctr Astron Avila, 14 Piso 2 Izq, Madrid 28008 - Spain

^[17] Tokyo Inst Technol, Dept Phys, Meguro Ku, 2-12-1 Ookayama, Tokyo 1528551 - Japan

^[18] Chinese Acad Sci, Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030 - Peoples R China

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 479, n. 2, p. 1672-1684, SEP 2018.
• Web of Science Citations: 3

Abstract

We present a multiwavelength spectral and temporal investigation of OJ 287 emission during its strong optical-to-X-ray activity between 2016 July and 2017 July. The daily. gamma-ray fluxes from Fermi-Large Area Telescope (LAT) are consistent with no variability. The strong optical-to-X-ray variability is accompanied by a change in power-law spectral index of the X-ray spectrum from <2 to >2, with variations often associated with changes in optical polarization properties. Cross-correlations between optical-to-X-ray emission during four continuous segments show simultaneous optical-ultraviolet (UV) variations, while the X-ray and UV/optical are simultaneous only during the middle two segments. In the first segment, the results suggest X-rays lag the optical/UV, while in the last segment X-rays lead by similar to 5-6 d. The last segment also shows a systematic trend with variations appearing first at higher energies followed by lower energy ones. The LAT spectrum before the very high-energy (VHE) activity is similar to preceding quiescent state spectrum, while it hardens during VHE activity period and is consistent with the extrapolated VHE spectrum during the latter. Overall, the broad-band spectral energy distributions (SEDs) during high-activity periods are a combination of a typical OJ 287 SED and a high-energy peaked (HBL) SED and can be explained in a two-zone leptonic model, with the second zone located at parsec scales, beyond the broad line region, being responsible for the HBL-like spectrum. The change of polarization properties from systematic to chaotic and back to systematic, before, during, and after the VHE activity, suggests dynamic roles for magnetic fields and turbulence. (AU)

• FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Special Projects
• FAPESP's process: 15/13933-0 - Probing relativistic jets and high energy emission through Multi-wavelength observation analysis
• Grantee: Pankaj Kushwaha
• Support Opportunities: Scholarships in Brazil - Post-Doctoral