4 2009 Fermi Symposium, Washington, D.C., Nov. 2-5
Figure 4: The γ-ray index versus submillimeter index plane. The blazars fall more steeply in the γ-rays than in the
submillimeter band, where most are, in fact, rising. This LAT-detected sample contrasts with the full SMA sample,
where the blazars are more distributed around αS ∼ 0.
as the presence of SSC versus ERC. Here, we use sub-
millimeter luminosity as a proxy for jet power, which
is correlated with the integrated luminosity of the syn-
chrotron component. Elevated γ-ray luminosity with
respect to the synchrotron component (which is often
seen in FSRQs) suggests the upscattering of external
photons oﬀ the synchrotron-emitting electrons. These
objects should occupy the upper right of the ratio/jet
power plot, and BL Lacs, which generally exhibit com-
ponents with roughly comparable luminosities, should
occupy the lower left. It is clear from the ﬁgure, how-
ever, that many FSRQs exhibit ratios similar to those
of the BL Lacs and vis versa.
Sikora et al. [10] report that, during its ﬂaring
epochs, 3C 454.3 transitions from its typical FSRQ
state to a more BL Lac-like state, where the syn-
chrotron component emits much more strongly com-
pared to the γ-ray component than during its “low
state”. 3C 454.3, which is the highest submillime-
ter luminosity FSRQ in our sample, would then shift
down and to the right in Figure 5 when it enters a
ﬂaring period. For the ﬁrst three months of the Fermi
mission, 3C 454.3 was not ﬂaring, which may explain
its present location in Figure 5. The three objects for
which there is a type discrepancy between CGRaBS
and LBAS are all FSRQs (in CGRaBS) and exhibit
low luminosity ratios and high luminosity, which sug-
gest they may be undergoing the same changes as 3C
454.3. A possible interpretation of the elevated lumi-
nosity ratios observed in some BL Lacs objects is that
there has been a dramatic increase in γ-ray luminos-
ity due to ERC, which would not be reﬂected in the
synchrotron component.
5. CONCLUSIONS
The motivation for observing blazars in the sub-
millimeter is to study behavior close to the central
engine, where the jet material is presumably still be-
ing accelerated. The separate emission processes that
contribute to overall SED may present diﬀerently in
BL Lacs and FSRQs, allowing us to understand the
similarities and diﬀerences between blazar types. We
have investigated these diﬀerences between objects in
terms of submillimeter behavior and, in conclusion,
ﬁnd that
•The SMA blazars exhibit submillimeter energy
spectral indexes that follow the spectral se-
quence interpretation of blazars.
eConf C091122