The MOJAVE Program: Investigating the ParsecScale Jet Properties of Gamma-Ray Blazars
Matthew Lister (Purdue) for the MOJAVE Team

Montage by M. Kadler et al.

MOJAVE CollaborationfM. Lister (P.I.), N. Cooper B. Hogan, S. Kuchibhotla, T.
Hovatta (Purdue)f

T. Arshakian, C.S. Chang, L. Fuhrmann, Y. Kovalev, A.
Lobanov, A. Pushkarev, T. Savolainen, J. A. Zensus (MaxPlanck Inst. for Radioastronomy)fM. and H. Aller (Michigan)fM. Cohen (Caltech)fD. Homan (Denison)f

M. Kadler (U. Erlangen-Bamberg)

fK. Kellermann (NRAO)

f

Y. Kovalev (ASC Lebedev)

fE. Ros (Valencia)

fN. Gehrels, J. McEnery, R. Sambruna, J. Tueller (GSFC)
We thank the LAT team for providing
preliminary 1st LAT catalog data
The MOJAVE Program is supported underNASA Fermi Grant NNX08AV67G and NSF
grant 0406923-AST.

Monitoring
OfJets inActive Galaxies withVLBA
Experiments
Very Long Baseline ArrayProject description:• Studying the long term structural evolution of pc-scale
jets in over 250 AGN
Æ mas-resolution full polarization images
Æ parallel studies of kpc x-ray and radio jets
• Complete AGN sample selected on the basis ofcompact, beamed radio emission (blazars)
Æ being extended to encompass newbright gamma-ray AGN

http://www.physics.purdue.edu/MOJAVE
Lister et al., 2009, AJ, 137, 3718

Recent findings (526 features in 127 AGN jets):f

Superluminal motions are the norm in radio-selected blazar jets
– typically ~10c, broad range up to 50 c: (PKS 0805-077)– motions are related to underlying flow
– caveat: in rare cases stationary bright features are seen near the base of the jetfBright features within a single jet typically move with similar
characteristic speed

Lister et al., 2009, AJ, (arXiv 0909.5100)

Recent findings:
f Over 1/3 of bright jet features are accelerating– creates the illusion of ‘bent jets’ in single epoch VLBA images– changes in speed are more common than changes in directionf Positive (speeding up) accelerations are moreprevalent close to the base of the jetÆ flows are still becoming organized on pc scales

3C 273
Homan et al., 2009, ApJ, (arXiv 0909.5102)

Recent findings:
Filled circles = VLBIOpen circles = single-dish

Kovalev et al. 2009,
ApJ 696, L17(see poster P1-19
by Kovalev et al. )Good correlation between Fermi LAT γ-ray photon flux and thequasi-simultaneously measured compact radio flux density.

Fermi+VLBA=Killer Combination for Blazar Science

Gamma-ray Flux

AC

Newly added
AGN from 1st
LAT Catalog

B

Preliminary!

~75% of
MOJAVE-1
is LATdetected

LAT data not
yet availableD

Non-simultaneous 15 GHZ VLBA Flux Density [Jy]

What makes an AGN γ–ray bright?
Complex combination of:
1. Preferred viewing angle
2. High jet Lorentz factor
3. High current activity state
4. High-peaked spectral energy distribution

Apparent Jet Opening Angles
f 3month MOJAVE-LAT

generally have broader
apparent openingangles than non-LAT

MOJAVE/LAT/TeV
HBL 1424+240

f Overall intrinsic

opening angle
distributions aresimilarÆThe bright LAT blazar
jets are typicallyviewed closer to theline of sight

PosterP1-8
Pushkarev et al., arXiv/0910.1813

Shaded: QSO

Doppler Factors

Unshaded = BL Lacs

f MOJAVE-LAT AGN jets
Savolainen et al., Poster P1-32Variability Doppler factor
non-LATLAT

have significantly higher
Doppler factors than
MOJAVE non-LAT
f Constrains viewing angle:θ < sin-1(δ-1)

Kuchibhotla et al., in prep.

Preliminary 1stLAT Catalog

Equipartition Lorentz factor

f Anisotropy of gamma-ray

emission may also
influence viewing angle
range – see Savolainen etal. poster P1-32

Apparent Jet Speeds
Preliminary 1st
LAT Catalog
fStrong correlation
between apparent speed
and radio luminosity

fLAT has now detectednearly every fast jet in theMOJAVE sample!

Lister et al. 2009, AJ, arXiv 0909.5100
Kadler et al., Poster P1-43

Compact radio luminosity [W/Hz]Apparent Jet Speeds
Preliminary 1stLAT Catalog

Kadler et al., Poster P1-43

Gamma-ray luminosity [erg/s]

Jet Activity States

Stacked image: 1995-2009f

At any given time, only the energized
portion of a broader jet is visiblef

Activity states of AGN jets evolve
over time– long quiescent periods of no blob ejection
are seen– new blobs ejected at new position angles– only 30% of the 3 month LAT AGN weredetected by EGRETÆAre changes in pc-radio jetmorphology reflected in the gamma-

YES – see poster
by Jorstad et al.
ray activity?

Image fromRecent
image:MarchJune1996
2009
Lister et al., 2009, AJ, 137, 3718

1308+326: BL Lac at z = 140 pc

MOJAVE complete sample activity in 2008
Activity index in radio band:
V=(S2008-S1999-2007)/S1999-2009

Fermi LATMOJAVE
non-detected
non-LAT

Statistical conclusions:
1. MOJAVE-LAT AGN are in a highactivity state, both in total
intensity, and polarization (KovalevP1-19, Hovatta P1-36, Aller P1-3)
MOJAVE
Fermi
LAT
LAT
detected

Black = γ-variable

2. Flares in radio and γ-ray domain
happen within a typical apparent
time separation of a few months

Does the jet beaming factor
change with activity state?
Kovalev et al., 2009, ApJ, (arXiv 0902.2085)

MOJAVE-LAT Summary
f Blazar gamma-ray emission originates on pc-scales inrelativistically moving plasma – likely shock fronts.
f Compared to other radio blazars, LAT-detected jets are:– faster and more highly beamed– more highly polarized and in a high active state in the radioÆ SED peak location plays a key role in BL Lac LAT detections(see posters P1-21, P1-42, P1-43 )f VLBA+Fermi is a fantastic tool for nailing down where

the gamma-rays are being produced within the jet.