Multiwavelength spectral and temporal analysis of VHE Blazar 1ES 1959+650: Tracing emission mechanisms across flux states

Abstract

The high-synchrotron-peaked BL Lac object 1ES\,1959+650 exhibited pronounced activity between MJD~60310 -- 60603, including a very high energy (VHE) detection reported by LHAASO. To investigate the underlying emission mechanisms, we performed a comprehensive temporal and spectral analysis using multiwavelength data from \textit{Swift}-XRT/UVOT and \textit{Fermi}-LAT, covering the optical/UV to GeV $\gamma$-ray bands. The source shows strong energy-dependent variability, with the largest fractional variability in $\gamma$-rays, followed by X-rays and UV/optical, consistent with leptonic emission scenarios. Based on the variability patterns, we identified distinct flux states (F1, F2, F3, F4, F5, VHE-FX1, and VHE-FX2). The X-ray spectra exhibit a clear ``harder-when-brighter'' trend across these states. We modeled the broadband spectral energy distributions (SEDs) using a one-zone model incorporating synchrotron and synchrotron self-Compton (SSC) emission, implemented in \textsc{xspec} using ${\chi }^2$ minimization. During the VHE detection, the corresponding X-ray/optical emission likely resembled the F2 state. Modeling the VHE SED using F1-state data led to an SSC overprediction of the VHE flux, whereas all other states were well described within the one-zone framework. Systematic trends in physical parameters are observed across flux states, including spectral hardening, increasing break energy, rising bulk Lorentz factor, and decreasing magnetic field with increasing flux. These results suggest that enhanced particle acceleration efficiency and stronger Doppler boosting drive the observed flaring activity, while the decrease in magnetic field indicates conversion of magnetic energy into particle kinetic energy, consistent with shock-driven scenarios.

arXiv comment11 pages, 3 figures

References in corpus (54)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The Swift Ultra-Violet/Optical Telescope
• Fermi Large Area Telescope Fourth Source Catalog
• Fermi Large Area Telescope Second Source Catalog
• A Unifying View of the Spectral Energy Distributions of Blazars
• On characterising the variability properties of X-ray light curves from active galaxies
• The Spectral Energy Distribution of Fermi bright blazars
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• Leptonic and Hadronic Modeling of Fermi-Detected Blazars
• Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations
• The Connection between X-ray- and Radio-Selected BL Lacertae Objects
• BL Lac Objects in the Synchrotron Proton Blazar Model
• Variable VHE gamma-ray emission from Markarian 501
• Structured jets in TeV BL Lac objects and radiogalaxies
• TeV Gamma Rays from BL Lac Objects due to Synchrotron Radiation of Extremely High Energy Protons
• The power of blazar jets
• Comptonization of Infrared Radiation from Hot Dust by Relativistic Jets in Quasars
• Multiwavelength Observations of Strong Flares From the TeV-Blazar 1ES 1959+650
• Particle acceleration at ultrarelativistic shocks: an eigenfunction method
• Modeling the Emission Processes in Blazars
• The blazar sequence: a new perspective
• A new population of very high energy gamma-ray sources in the Milky Way
• A hadronic origin for ultra-high-frequency-peaked BL Lac objects
• Multiwavelength Observations of a Flare from Markarian 501
• X-Ray Spectral Variability Signatures of Flares in BL Lac Objects
• Simultaneous multiwavelength observations of the second exceptional gamma-ray flare of PKS 2155-304 in July 2006
• The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies
• The Deep X-Ray Radio Blazar Survey (DXRBS). III. Radio Number Counts, Evolutionary Properties, and Luminosity Function of Blazars
• Log-parabolic spectra and particle acceleration in blazars - II: The BeppoSAX wide band X-ray spectra of Mkn 501
• Detection of TeV Gamma Rays from the BL Lac Object 1ES1959+650 with the Whipple 10m Telescope
• Simultaneous multiwavelength observations of the blazar 1ES1959+650 at a low TeV flux
• Active galactic nuclei at gamma-ray energies
• Observation of VHE gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 using the MAGIC telecope
• A multi-zone model for simulating the high energy variability of TeV blazars
• A hadronic synchrotron mirror model for the "orphan" TeV flare in 1ES 1959+650
• Multiwavelength Variability Signatures of Relativistic Shocks in Blazar Jets
• Modelling the VHE flare of 3C 279 using one zone leptonic model
• Investigating Broadband Variability of the TeV Blazar 1ES 1959+650
• The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies
• Broadband characterisation of the very intense TeV flares of the blazar 1ES 1959+650 in 2016
• The Proton Blazar
• A hard gamma-ray flare from 3C 279 in 2013 December
• Broadband Spectral Fitting of Blazars using XSPEC
• Study on Temporal and Spectral behavior of 3C 279 during 2018 January flare
• Broadband study of blazar 1ES 1959+650 during flaring state in 2016
• Leptonic and Lepto-Hadronic Modeling of the Nov. 2010 flare from 3C 454.3
• Influence of Energy-Dependent Particle Diffusion on the X-ray spectral curvature of MKN 421
• Gamma-ray emission and spectral evolution of pair plasmas in AGN jets
• Establishing the Spectral Turnover of Blazar PKS 2155-304 as an Outcome of Radiative Losses
• Unveiling the broadband spectral and temporal properties of PKS\,0903-57 during its brightest flare
• Very High Energy Flat Spectral Radio Quasar Candidates

Cited by in corpus (1)

• Peculiar Behavior of Optical Polarization in Blazar 1ES 1959+650: Role of Jet Magnetic Field and Geometry