Are Jets Monoparametric? Extending the Blazar Sequence to the Blazar Envelope in the Fermi Era

The blazar sequence, first discovered by Fossati et al. (1998), unified the broad emission line, high-powered flat spectrum radio quasars (FSRQ) with the optically featureless BL Lac objects through a simple anti-correlation between synchrotron peak luminosity and peak frequency. This paradigm has come under scrutiny as increasing numbers of sources have emerged off the sequence. We have found evidence for a simple underlying scheme for the apparent 'blazar envelope': blazar jets are mono-parametric engines, such that source power (as measured from the low-frequency, un-beamed extended emission) creates a monotonic relationship between the intrinsic peak luminosity and peak frequency of the synchrotron and inverse Compton components. The envelope naturally emerges below the sequence due to the drop in peak luminosity and frequency as sources are progressively aligned away from our line-of-sight and relativistic beaming drops. We present key evidence for this scheme which has impact on theoretical models of blazar jets with velocity profiles. The envelope also allows us to more clearly unify blazars and the parent population of FR I and II radio galaxies. I will discuss some of the difficulties and caveats in measuring the source power through extended emission, current results, and future applications of this simple idea to broader unification schemes and other source classes.