1. How to classify a Gamma -ray source as a Blazar
P. Giommi
August 2005

3. Definition based on observed properties
Blazar :
Broad-lined (FSRQ) or featureless (BL Lac)
AGN with
Flat radio spectrum
Fast variability
High and variable polarization
Superluminal motion
etc.

4. Paradigm-driven definition
AGN : Two main categories
Powered by Accretion (AP-AGN)
Powered by Non-Thermal radiation emitted in a Jet
(NT-AGN)
Blazars:
NT-AGN viewed at a small angle w.r.t. jet axis
Radio Galaxies:
NT-AGN viewed at a large angle w.r.t. jet axis
Broad-line radio galaxy (e.g. 3c120) :
A combination of AP-AGN and “misdirected” NT-AGN

5. SSC and the ox - ro diagram
Blazar region

6. Radio galaxies and the ox - ro diagram
WMAP 150 = Pictor A
Nuclear compact radio emission
Radio galaxies

7. Energy bands with additional (confusing) components
Host galaxy
Extended radio emission
Radiation from accretion

8. Max EGRET
Min EGRET


9. Operational definition of Blazar to be used for GLAST catalog
NT-AGN or Synchro-Compton
region
radio galaxies
Case where -ray detection is postionally associated with a source for which
radio (at least one frequency),
optical
X-ray flux
are known. ( ~25% of the cases )
ox and ro within NT-AGN region
Additional characteristics that increase probability
Variable source,
radio-optical polarization
r < threshold value and/or
Radio compactness > threshold and/or
rx > threshold value
Blazar, else Radio galaxy
Additional condition ensuring goodness
of AGN-GLAST source association
r > within observed range, -
might change with time- [better  > 0.8 ]

10. Operational definition of Blazar to be used for GLAST catalog
NT-AGN or Synchro-Compton
region
radio galaxies
Case where -ray source is postionally
associated with a source for which
radio (at least two frequencies),
optical
are known. (~75% of the cases)
ro > 0.2 and r< threshold value
Additional characteristics that increase probability
Variable source,
radio or optical polarization
Additional condition ensuring goodness
of AGN-GLAST source association
r > within observed range, -
might change with time- [better  > 0.8 ]
Radio compactness > threshold value
Blazar, else Radio galaxy

11. radio (at least two frequencies), optical
Operational definition of Non-Thermal radiation dominated AGN (NT-AGN) to be used for GLAST catalog
Case where -ray source is postionally associated with a source for which
radio (at least two frequencies),
optical
are known. (~75% of the cases)
NT-AGN or Synchro-Compton
region
radio galaxies
ro > 0.2 and r< threshold value
Radio compactness > threshold value
Blazar, else Radio galaxy
Additional condition ensuring goodness of AGN-GLAST source association
r > within observed range, - might change with time-
[better  > 0.8 ]