X-ray spectral curvature of High Frequency Peaked BL Lacs: a predictor for the TeV flux

Abstract

Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of "high frequency peaked BL Lacs" (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved, and well described in terms of a log-parabolic shape. In a previous investigation of TeV HBLs (TBLs) we found two correlations between their spectral parameters. (1) The synchrotron peak luminosity L_p increases with its peak energy E_p; (2) the curvature parameter b decreases as E_p increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Here we present an extensive X-ray analysis of a sample of HBLs observed with XMM-Newton and SWIFT but undetected at TeV energies (UBLs), to compare their spectral behavior with that of TBLs. Investigating the distributions of their spectral parameters and comparing the TBL X-ray spectra with that of UBLs, we develop a criterion to select the best HBLs candidates for future TeV observations.

25 pages, 6 figures, Astrophysical Journal published

References in corpus (9)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent Is the Universe?
• Roma-BZCAT: A multifrequency catalogue of Blazars
• On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field
• X-ray spectral evolution of TeV BL Lac objects: eleven years of observations with BeppoSAX, XMM-Newton and SWIFT satellites
• Signatures of synchrotron emission and of electron acceleration in the X-ray spectra of Mrk 421
• Spectral Hardening of Large Solar Flares
• Swift XRT and UVOT deep observations of the high energy peaked BL Lac object PKS 0548-322 close to its brightest state
• The multicomponent model of the Crab Pulsar at energies above 25 GeV

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