I.Introduction  Recent evidence from Fermi and the VLBA has revealed a strong connection between ɣ -ray emission in AGNs and their parsec-scale radio jet properties.  We present the first VLBA study of a complete sample of the brightest radio- and ɣ -ray selected AGNs in the northern sky, based on data from the successful MOJAVE program.  This joint Fermi-VLBA dataset is ideal for examining the influences of relativistic beaming and spectral energy distribution (SED) shape on blazar jet properties. Matthew Lister, Department of Physics, Purdue University on behalf of the MOJAVE and LAT collaborations ɣ -ray Loudness and the Parsec-Scale Jet Properties of MOJAVE Blazars VI. Summary -We have identified an important continuous trend among the brightest ɣ -ray BL Lacs: as the SED synchrotron peak moves to lower energies, the ɣ -ray to radio flux ratio drops, the LAT ɣ -ray spectrum steepens, and the radio core emission becomes more compact. -These trends are not seen among the quasars, which suggests that the BL Lacs have intrinsically slower jets and lower Doppler boosting factors than quasars, in both the ɣ -ray and radio regimes. This poses a challenge for spine/sheath models for TeV-emitting BL Lac jets, in which the ɣ -ray emission is much more highly beamed than the radio. We are currently gathering proper motion jet speeds on the full sample with MOJAVE to further investigate this scenario. Figure A Figure B Figure C II. The MOJAVE Survey  Monitoring Of Jets in Active Galactic Nuclei with VLBA Experiments (Lister et al. 2009, AJ, 137, 3718)  Regular full polarimetric imaging program of nearly 300 bright AGN above declination -30º  The sample includes a complete list of radio- and ɣ -ray selected blazars. Sources are observed every 3 weeks to 3 years, depending on their jet expansion rates.  Parallel studies ongoing with VLA (20 cm), Chandra, and Swift: see III. The Sample  Our AGN sample in this study is complete for:  the sky region above dec. = -30º, |b| > 10º  median >100 MeV energy flux > 3x erg s -1 cm -2 OR  15 GHz VLBA flux density has exceeded 1.5 Jy  Fluxes for the sample selection were measured during the initial 11 month Fermi mission period.  There are 173 AGNs in total, 48 are both radio- and ɣ -ray selected (top right corner of Figure 1)  Optical classes:  15 high energy peaked BL Lacs  31 low and intermediate peaked BL Lacs  120 quasars, 4 radio galaxies, 3 unidentified IV. ɣ -ray-selected vs. radio-selected blazars  The ɣ -ray and radio-selected AGNs form part of the same continuous trend in Figure 2 and have similar redshift distributions.  The ɣ -ray-selected blazar class contains an additional population of low-redshift BL Lacs with synchrotron peaks located above Hz.  The addition of the radio-selected AGNs with ɣ -ray upper limits in Figure 2 suggests that the distribution is in the form of an envelope.  Relativistic beaming predicts such an upper envelope if there is an upper limit on jet speed in the parent population and a tight intrinsic ɣ -ray-radio luminosity correlation (Lister & Marscher 1999) V. What makes certain blazars ɣ -ray bright?  The ɣ -ray loudness of BL Lacs (ratio of ɣ -ray to VLBA radio luminosity) is primarily determined by the location of their synchrotron peak.  Because of the fixed locations of the radio and LAT bands, BL Lacs peaked at lower energy are less ɣ -ray loud (Fig 4), and have steeper ɣ -ray spectra (Fig 5, & Abdo et al. 2010, ApJ 716, 30).  The radio core brightness temperatures of the high-energy peaked BL Lacs are low (Fig 3), implying lower Doppler boosting factors.  None of these trends hold for quasars, most likely since they do not have synchrotron peaks above Hz and have a wider range of Doppler factors. The latter would magnify any differences in the relative boosting of ɣ -ray vs. radio emission. Figure 1: ɣ -ray energy flux vs. radio VLBA flux density. Arrows denote derived upper limits on the Fermi LAT fluxes. Figure 2: ɣ -ray vs. VLBA radio luminosity. The BL Lacs and quasars are part of a continuous trend spanning 6 orders of magnitude. The ɣ -ray loudest AGNs are located furthest from the 1:1 dashed line. VII. Acknowledgements M. Lister wishes to acknowledge the contributions of the MOJAVE and LAT teams, and members of the Owens Valley and U. Michigan Radio Observatories in providing supporting data for this work. The MOJAVE project is supported under National Science Foundation grant AST and NASA-Fermi grant NNX08AV67G. Figure 3: ɣ -ray loudness versus radio core brightness temperature. Figure 4: ɣ -ray loudness versus location of synchrotron peak. Figure 5: ɣ -ray loudness versus ɣ -ray photon index. ABSTRACT: The MOJAVE program is regularly observing nearly 300 bright AGNs with the VLBA at 15 GHz in order to study the kinematics, physics and evolution of parsec-scale radio jets. Here we examine the ɣ -ray to radio luminosity ratios and parsec-scale radio jet properties of a complete sample of the brightest ɣ -ray and radio-selected AGNs in the northern sky. Within this sample there is at least a three order of magnitude range in ɣ -ray loudness, which reflects the strong influences of relativistic beaming and spectral energy distribution class on the jet properties of the brightest blazars. We find that for BL Lac objects, as the SED synchrotron peak moves to lower energies, the ɣ - ray to radio flux ratio drops, the LAT ɣ -ray spectrum steepens, and the radio core emission becomes more compact. This behavior is not seen among the quasars, which suggests that the BL Lacs have intrinsically slower jets and lower Doppler factors than flat-spectrum quasars, in both the radio and ɣ -ray regimes Preliminary