From the "blazar sequence" to unification of blazars and radio galaxies

Abstract

Based on a large Fermi blazar sample, the blazar sequence (synchrotron peak frequency ${\nu }_{\mathrm{peak}}$ versus synchrotron peak luminosity $L_{\mathrm{peak}}$) is revisited. It is found that there is significant anti-correlation between ${\nu }_{\mathrm{peak}}$ and $L_{\mathrm{peak}}$ for blazars. However, after being Doppler corrected, the anti-correlation disappears. The jet cavity power ($P_{\mathrm{jet}}$) is estimated from extended radio luminosity. So it is free of beaming effect. We find that there are significant anti-correlations between $P_{\mathrm{jet}}$ and beam-corrected ${\nu }_{\mathrm{peak}}^{{}^{\prime }}$ for both blazars and radio galaxies, which supports the blazar sequence and unification of blazars and radio galaxies (an alternative relationship is the correlation between jet power and $\gamma$-ray photon index).

7 pages, 2 table, 5 figures, accepted for publication in MNRAS