Spectral Energy Distributions for TeV Blazars

Abstract

In this work, we collected a sample of 69 TeV blazars from TeVCat, obtained their multi-wavelength observations, and fitted their spectral energy distributions by using the second degree polynomial function. The structure parameters of the synchrotron bumps for 68 blazars and those of the inverse-Compton bumps for 56 blzars are obtained. Then, we adopted statistical analysis to the parameters (curvature, peak frequency, peak luminosity, bolometric luminosity, and X/$\gamma$-ray spectral indexes). From our analysis and discussions, we can get following conclusions: 1. There is a clear positive correlation between the synchrotron peak frequency, $\log \nu_p^s$, and the inverse-Compton peak frequency $\log \nu_p^{IC}$, and that between the synchrotron peak luminosity, $\log \nu_p^s L_p^s$, and the inverse-Compton peak luminosity, $\log \nu_p^{IC}L_p^{IC}$. 2. The correlation between the peak frequency and the curvature of synchrotron bump is clearly different from that of the inverse-Compton bump, which further indicates that there are different emission mechanisms between them. 3. There is a correlation between $\log \nu_p^{IC}$ and $\gamma$-ray spectral index, $\alpha_\gamma$, for the TeV blazars: $\log \nu^{IC}_p = -(4.59 \pm 0.30) \alpha_\gamma + (32.67 \pm 0.59)$, which is consistent with previous work of Abdo et al.(2010). 4. An "L-shape" relation is found between $\log \nu^s_p$ and $\alpha_X$ for both TeV blazars and Fermi blazars. A significant correlation between $\log \nu^s_p$ and X-ray photon index ($\alpha_X$) is found for the TeV blazars with high synchrotron peak frequency: $\log \nu^{s}_{p} = -(3.20 \pm 0.34) \alpha_X + (24.33 \pm 0.79)$, while the correlation is positive for low synchrotron peaked TeV sources. 5. In the $\alpha_X-\alpha_\gamma$ diagram, there is also an "L-shape", the anti-correlation is consistent with the available results in the literature, (...)