SSC radiation in BL Lac sources, the end of the tether

Abstract

The synchrotron-self Compton (SSC) radiation process is widely held to provide a close representation of the double peaked spectral energy distributions from BL Lac Objects (BL Lacs), which are marked by non-thermal beamed radiations, highly variable on timescales of days or less. Their outbursts in the gamma ray relative to the optical/X rays might be surmised to be enhanced in BL Lacs as these photons are upscattered via the inverse Compton (IC) process. From the observed correlations among the spectral parameters during optical/X-ray variations we aim at predicting corresponding correlations in the gamma-ray band, and the actual relations between the gamma-ray and the X-ray variability consistent with the SSC emission process. We start from the homogeneous single-zone SSC source model, with log-parabolic energies distributions of emitting electron as required by the X-ray data of many sources. We find relations among spectral parameters of the IC radiation in both the Thomson (for Low energy BL Lacs) and the Klein-Nishina regimes (mainly for High energy BL Lacs) and we compute how variability is driven by a smooth increase of key source parameters, primarily the root mean square electron energy. The single component SSC source model in the Thomson regime turns out to be adequate for many LBL sources. However, the simple model meets its limits with the fast/strong flares recently reported for a few sources in the TeV range; these require sudden accelerations of emitting electrons in a second source component.

12 pages, 2 tables, 8 figures

References in corpus (8)

• Implications of very rapid TeV variability in blazars
• Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability
• X-ray spectral evolution of TeV BL Lac objects: eleven years of observations with BeppoSAX, XMM-Newton and SWIFT satellites
• Discovery of very high energy gamma-ray emission from the low-frequency peaked BL Lacertae object BL Lacertae
• Signatures of synchrotron emission and of electron acceleration in the X-ray spectra of Mrk 421
• Simultaneous multiwavelength observations of the blazar 1ES1959+650 at a low TeV flux
• AGILE detection of variable gamma-ray activity from the blazar S5 0716+714 in September-October 2007
• AGILE and Swift simultaneous observations of the blazar S50716+714 during the bright flare of October 2007

Cited by in corpus (36)

• The Extragalactic Gamma-ray Sky in the Fermi era
• The curvature of spectral energy distribution of blazars
• The physical properties of $Fermi$-4LAC flat spectrum radio quasars
• On the origin of the hard X-Ray excess of high-synchrotron-peaked BL Lac object Mrk 421
• X-ray and TeV emissions from High Frequency Peaked BL Lacs
• Radio Weak BL Lac objects in the Fermi era
• X-ray spectral curvature of High Frequency Peaked BL Lacs: a predictor for the TeV flux
• Near-Equipartition Jets with Log-Parabola Electron Energy Distribution and the Blazar Spectral-Index Diagrams
• Flaring Patterns in Blazars
• Powerful high energy emission of the remarkable BL Lac object S5 0716+714
• Charge-starved, relativistic jets and blazar variability
• The Intrinsic Properties of Multiwavelength Energy Spectra for Fermi Teraelectronvolt Blazars
• Signature of Inverse Compton emission from blazars
• The physical properties of \textit{Fermi} TeV BL Lac objects jets
• The Hard X-ray emission of the blazar PKS 2155--304
• Curvature of the spectral energy distribution, the dominant process for inverse Compton component and other jet properties in Fermi 2LAC blazars
• VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study
• Multi-wavelength study of flaring activity in HBL 1ES 1959+650 during 2015-16
• Power for dry BL Lacertae objects
• A two-zone photohadronic scenario for EHBL-like behavior of Mrk 501
• The $\gamma$-ray sky seen at X-ray energies I. Searching for the connection between X-rays and $\gamma$-rays in Fermi BL Lac objects
• Gamma Ray Bursts in the Fermi era: the spectral energy distribution of the prompt emission
• Dynamic changes of emitting electron distribution in the jet of 3C 279: signatures of acceleration and cooling
• The Blazar Emission Environment: Insight from Soft X-ray Absorption
• Spectral evolution of long Gamma Ray Burst prompt emission: electrostatic acceleration and adiabatic expansion
• From Radio to TeV: The surprising Spectral Energy Distribution of AP Librae
• On the intrinsic shape of gamma-ray spectrum for Fermi blazars
• Correlations between X-ray spectral parameters of Mkn 421 using long-term Swift-XRT data
• Probing the physical properties of the intergalactic medium using blazars
• Mechanism of very high energy radiation in BL Lacertae object 3C 66A
• Constraining X-ray emission in HBL blazars using multiwavelength observations
• Long-term hard X-ray variability properties of Swift-BAT blazars
• Probing the physical properties of the IGM using SRG/eROSITA spectra from blazars
• Disentangling the nature of the prototype radio weak BL Lac: Contemporaneous multifrequency observations of WISE J141046.00 + 740511.2
• Investigating the variability of Swift-BAT blazars with NICER
• Temporary EHBL-like behavior of Markarian 501 during July 2014 VHE flaring