Simultaneous Optical to X-ray Spectra of OJ 287: Insights into X-ray spectral changes and particle spectra

Abstract

OJ 287 is one of the most dynamic BL Lacertae objects that has exhibited behaviour representative of the entire blazar class and is also one of the best sources with simultaneous multi-wavelength coordinated data. Motivated by strong X-ray variability exhibited by the source, we systematically investigated the simultaneous optical to X-ray emission of the source with a focus on the spectral state of the lowest recorded X-ray flux state to understand the X-ray spectral changes. The optical-UV emission being synchrotron, the associated spectral variation is a direct reflection of the high-energy end of the underlying particle spectrum and its power-law continuation to X-rays can drastically affect the X-ray spectrum without much change in optical flux. Thus the combined optical to X-ray provides a potential tool to investigate and explore particle spectrum as well as highest particle energies. We report the finding of a power-law optical-UV spectrum with a photon spectral index of 2.71 $\pm$ 0.03 continuing to X-ray energies and accounting for this contribution at X-ray results in a photon spectral index of 1.15-1.3. We discuss the possible implications of this on X-ray spectral variations and the particle spectrum.

10 pages, 3 figures, ISRA 2023 conference proceeding, to be published (submitted version of the accepted proceeding, does not incorporate any post-submission improvements or corrections)

References in corpus (21)

• Evidence for neutrino emission from the nearby active galaxy NGC 1068
• A characteristic optical variability timescale in astrophysical accretion disks
• Polarized Blazar X-rays imply particle acceleration in shocks
• On the two main classes of Active Galactic Nuclei
• Hard TeV spectra of blazars and the constraints to the IR intergalactic background
• Gamma-ray Flux Distribution and Non-linear behavior of Four LAT Bright AGNs
• Multi-wavelength temporal and spectral variability of the blazar OJ 287 during and after the December 2015 flare: a major accretion disc contribution
• A peculiar multi-wavelength flare in the Blazar 3C 454.3
• X-ray spectral components of the blazar and binary black hole candidate OJ 287 (2005-2020)
• Strong Soft X-ray Excess in 2015 XMM-Newton Observation of BL--Lac OJ~287
• Refining the 2022 OJ 287 impact flare arrival epoch
• Multi-wavelength Analysis and Modeling of OJ 287 During 2017-2020
• Long Term Multi-band Near Infra-Red Variability of the Blazar OJ 287 during 2007--2021
• A possible tidal disruption event candidate in the black hole binary system of OJ 287
• Discovering the Mass-Scaled Damping Timescale from Microquasars to Blazars
• Quasi-simultaneous Optical Flux and Polarization Variability of the Binary Super Massive Black Hole Blazar OJ 287 from 2015 to 2023: Detection of an Anticorrelation in Flux and Polarization Variability
• Spectral States of OJ 287 blazar from Multi-wavelength Observations with $AstroSat$
• MOMO V. Effelsberg, Swift and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity
• Hard X-ray properties of radio-selected blazars
• Clues on the nature of the quasi-periodic optical outbursts of the blazar OJ 287
• On the Spectral Changes of OJ 287: The Lowest X-ray state Spectrum -- extended at Optical-UV and Hard at X-rays