# Fermi and Jansky: Our Evolving Understanding of AGN

November 10-12, 2011
Harbourtowne Conference Center
St Michaels, MD, USA

## Talk Abstracts

Name: Emmanouil Angelakis

Title: F-GAMMA program - review and recent findings: Unification and
physical interpretation of the radio spectra variability patterns in
Fermi blazars and jet emission from NLSy1s

Authors: E. Angelakis, L. Fuhrmann, I. Nestoras, R. Schmidt,
C. M. Fromm, J. A. Zensus, N. Marchili, T. P. Krichbaum
(Max-Planck-Institut fur Radioastronomie), H. Ungerechts, A. Sievers,
D. Riquelme (Instituto de Radio Astronoma Milimtrica (IRAM)),
M. Perucho-Pla (Departament dAstronomia i Astrofsica. Universitat de
Valencia)

Abstract: F-GAMMA program - review and recent findings: Unification
and physical interpretation of the radio spectra variability patterns
in Fermi blazars and jet emission from NLSy1s

The F-GAMMA program aims at understanding the physics at work in AGNs
via a multi-frequency monitoring approach. A number of roughly 65
Fermi-GST detectable blazars are being monitored monthly since January
2007 at radio wavelengths. The core program relies on the 100-m
Effelsberg telescope operating at 8 frequencies between 2.6 and 43
GHz, the 30-m IRAM telescope observing at 86, 145 and 240 GHz and the
APEX 12-m telescope at 345 GHz. For the targeted sources the LAT
instrument onboard Fermi-GST provides gamma-ray light curves sampled
daily. Recently the program has further expanded with the
participation of the Korean VLBI network, the Abastumani optical
observatory and the Skinakas observatory for optical polarimetry.

Here we will discuss:

A. A review of all participating facilities and the main
characteristics of the program (sources sample, frequency coverage,
sampling etc.). The recent developments in optical coverage (in total
power and polarization) will also be discussed.

B. We show that, on the basis of their variability pattern, the
observed quasi-simultaneous broad-band spectra can be classified to
merely 5 classes. The variability for the first 4 is clearly dominated
by spectral-evolution while sources of the last class vary
self-similarly with almost no apparent shift of the peak frequency. It
is shown that the former classes can be attributed to exactly the same
two-component system made of (a) a quiescent optically thin spectrum
and (b) a superposed flaring event; whereas the latter class must be
interpreted in terms of a completely different mechanism. The apparent
differences among the classes are explained in terms of a redshift
modulus and an intrinsic-source/flare parameters modulus.

Numerical simulations we have conducted show that a shock-in-jet model
can very well describe the observed behavior. On the other hand, it is
shown that the ability of the shock-in-jet to reproduce the behavior
of sources that cover a broad spectrum of intrinsic properties
indicates its universality.

It is concluded that only two mechanisms seem to be producing
variability. None of the almost 90 sources used for this study show a
switch of class indicating that the variability mechanism is either
(a) a finger-print of the source, or (b) that the parameters it may
depend on vary at timescales far longer than the monitoring period of
almost 4 years.

C. Finally, we discuss recent findings of the program such as
red-shift bias free correlation between radio and gamma-ray flux
density. Furthermore, recently it has been found that besides the
to be the gamma-ray emitting AGNs, Narrow Line Seyfert 1 galaxies also
show gamma-ray emission. Within the F-GAMMA program radio jet emission
has been detected from 3 such sources challenging the belief that jets
are associated with elliptical galaxies. The results of their
monitoring will be discussed.

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Name: Jay Blanchard

Title: The gamma-ray blazar B0208-512, a multi-wavelength investigation.

Authors: Jay Blanchard, School of Mathematics & Physics, University of
Tasmania, Australia.
Jim Lovell, School of Mathematics & Physics, University of Tasmania, Australia.
Roopesh Ojha, NASA Goddard Space Flight Center, USA
Matthias Kadler, University of Wurzburg, Germany;
Roberto Nesci, University La Sapienza, Italy;
Philip Edwards, CSIRO Astronomy and Space Science, ATNF, Australia
Michael Dutka, Catholic University, USA
Tapio Pursimo, Nordic Optical Telescope, Santa Cruz de La Palma, Spain;
John Dickey, School of Mathematics & Physics, University of Tasmania,
Australia.

Abstract: PKS B0208-512 is a blazar at a redshift of 1.0. VLBI
observations show a strong core and a one sided jet. It was detected
by the ROSAT all sky survey as an X-ray source and as a gamma-ray
source by EGRET. Since the launch of Fermi, PKS B0208-512 has shown
flaring behaviour in the gamma-ray band on at least three separate
occasions. VLBI and radio light-curve monitoring observations of PKS
B0208-512 is being conducted as part of the TANAMI
program. Single-dish flux-density monitoring data obtained with the
30m Ceduna telescope date back to 2004 and show strong flaring
have been made using the Australia Telescope Compact Array and the
source has been monitored in the optical band by the REM
telescope. Archival X-ray and UV data have been obtained from the
Swift satellite and its evolving parsec scale structure is being
monitored with VLBI observations using the TANAMI array. We present
the results of these multiwavelength observations and discuss the
implications they have for the origin and nature of high energy
emission from this blazar. In particular, we investigate the non
simultaneous nature of the flaring at different frequencies.

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Name: Markus Boettcher

Title: Modeling broadband spectra and variability of blazars

Authors: Markus Boettcher
Astrophysical Institute
Department of Physics and Astronomy
Ohio University
Athens, OH 45701
USA

Abstract: In this talk I will present a review of the current
state-of-the-art of models for the broadband spectral energy
distributions and variability of blazars. Both leptonic and hadronic
models for blazar emission will be considered, with special attention
to possible diagnostics to distinguish between those two classes of
models. I will highlight areas of future progress to be made with
continued Fermi as well as future CTA observations.

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Name: Amanda Dotson

Title: A Diagnostic for Determining the Location of the GeV Emission
in powerful blazars

Authors: Amanda Dotson (University of Maryland Baltimore County),
Markos Georganopoulos (University of Maryland Baltimore
County,NASA/GSFC) , Demosthenes Kazanas (NASA/GSFC), Eric Perlman
(Florida Institute of Technology)

Abstract: A central issue currently debated in the literature is how
far from the black hole is the {sl Fermi} observed GeV emission of
powerful blazars emitted. Here we present a clear diagnostic tool for
testing whether the GeV emission site is located within the sub-pc
broad emission line (BLR) region or further out in the few pc scale
molecular torus environment.  Within the BLR the scattering takes
place at the onset of the Klein-Nishina regime, causing the electron
cooling time to become practically energy independent and as a result,
the variation of high-energy emission is expected to be achromatic.
Contrarily, if the blazar is outside the BLR, the expected GeV
variability is energy-dependent and with amplitude increasing with
energy.  We demonstrate this using time-dependent numerical
simulations of blazar variability.  The proposed work holds the
promise of settling this important issue.

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Name: Thomas Eberl

Title: The ANTARES neutrino telescope

Authors: Thomas Eberl, Erlangen Centre for Astroparticle Physics,
Erwin-Rommel-Str. 1, D-91058 Erlangen for The ANTARES collaboration

Abstract: The ANTARES deep-sea neutrino telescope currently is the
largest neutrino detector in the Northern Hemisphere. The instrument
consists of a three-dimensional array of 885 photomultiplier tubes,
arranged in 12 lines anchored at a depth of 2500m in the Mediterranean
Sea, 40km offshore from Toulon (France). An additional instrumented
line is used for environmental monitoring and for R&D towards acoustic
neutrino detection. The photomultiplier tubes detect the Cherenkov
radiation of charged secondary particles produced by high-energy
neutrinos interacting in or around the detector. Charged-current
interactions of muon neutrinos is the reaction channel of central
interest. The trajectories of the resulting muons are reconstructed
with high precision, revealing the direction of the incoming
neutrinos. ANTARES is taking data with its full 12 line configuration
since May 2008, and has been operated before in a 5 and 10 line setup
for more than a year. The calibration, performance and long-term
stability of the detector will be discussed. Studies have been
underway to search for neutrino point sources in the ANTARES data
since 2007. Results from these studies and the sensitivity of the
telescope will be discussed.

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Name: Phil Edwards

Title: Before Fermi met Jansky

Authors: P.G. Edwards
CSIRO Astronomy & Space Science

Abstract: Radio monitoring of gamma-ray emitting AGN in the EGRET era
will be reviewed and key findings summarised, and efforts underway to
continue, and improve upon, these studies in the Fermi era described.

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Name: Manel Errando

Title: Blazar observations above 100 GeV with VERITAS

Authors: Manel Errando (Barnard College / Columbia University) on
behalf of the VERITAS collaboration.

Abstract: The VERITAS array of 12-m atmospheric-Cherenkov telescopes
in southern Arizona is one of the world‚Äôs most sensitive detectors
of VHE (E>100 GeV) gamma rays. There are ~50 extragalactic sources
which are known to emit VHE photons, including blazars, radio
galaxies, and starburst galaxies. Blazar observations are one of the
VERITAS Collaboration‚Äôs Key Science Projects. More than 400 hours
per year are devoted to this program and ~100 blazars have already
been observed with the array, in most cases with the deepest-ever VHE
exposure. These observations have resulted in 21 detections, including
10 VHE discoveries, all of them with supporting multiwavelength
observations. Recent highlights from VERITAS extragalactic observation
program and the collaboration's long-term blazar observation strategy
will be presented.

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Name: Justin Finke

Title: A Physical Model for the Revised Blazar Sequence

Authors: Justin Finke (US Naval Research Laboratory) and Charles
Dermer (US Naval Research Laboratory)

Abstract: The blazar sequence is reflected in a plot of the peak
luminosity versus peak frequency of the synchrotron component of
blazars. This diagram has been considered one of the fundamental
pieces of evidence for the existence of a continuous sequence that
includes low-power BL Lacertae objects through high-power flat
spectrum radio quasars.  Recently, Some authors (e.g., Meyer et al.)
have shown that this plot displays an "L" or "V" shape that was not
apparent in earlier representations of the blazar sequence.  We find
that this shape can be reproduced by a simple model where the external
radiation field increases with increasing injection power of jet
electrons. This leads to greater cooling of the electrons, which moves
the synchrotron peak to lower frequencies.  For more powerful
injection, the electron cooling Lorentz factor becomes less than the
minimum injected electron Lorentz factor, causing the peak frequency
to become nearly independent of the jet power.  The difference in
viewing angles of different blazars can explain the scatter in the
sequence.

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Name: Lars Fuhrmann

Title: Study of cm/mm-band radio and gamma-ray correlated variability
in Fermi bright blazars

Authors: L. Fuhrmann (MPIfR), S. Larsson (Stockholm Univ.) , J. Chiang
(Stanford Univ.), E. Angelakis (MPIfR), I. Nestoras (MPIfR) on behalf
of the F-GAMMA and Fermi/LAT collaborations

Abstract: We present preliminary results of a study focusing on the
possible connection between radio and gamma-ray flares/activity
periods in the lightcurves of about 50 Fermi-GST detected blazars. For
this purpose, the long-term cm/mm radio data obtained within the
F-GAMMA program are combined with monthly sampled long-term LAT
gamma-ray lightcurves starting in 2008. A detailed statistical
cross-band analysis is presented together with more direct methods
(e.g. light curve parameters, simultaneous flux-flux evolution) to
find significant correlations, and extract parameters like delays,
relative timing/onsets of events etc. Possible differences between
different source types and possible correlations with other parameters
(e.g. spectral types, luminosity, SED peaks) are also explored.

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Name: Paola Grandi

Title: Exploring  the FRI/FRII radio dichotomy  with the Fermi satellite

Authors: Paola Grandi
on behalf of the Fermi Collaboration

Abstract: We review the high energy properties of Misaligned AGNs
associated with gamma-ray sources detected by Fermi in 24 months of
survey.  Most of them are nearby low power radio galaxies (i.e. FRIs)
which probably have structured jets. On the contrary, high power radio
sources (i.e. FRIIs) with GeV emission are rare. The small number of
FRIIs does not seem to be related to their higher redshifts. We
suggest that beaming/jet structural differences are responsible for
the detection rate discrepancy observed between FRIs and FRIIs.

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Title: The Implications of Second-order SSC for the Gamma-ray Spectra
of Blazars

Authors: Adam Higuera, UMBC, University of Michigan-Ann Arbor
Markos Georganopoulos, UMBC, NASA/GSFC
Eric Perlman, FIT
Demos Kazanas, NASA/GSFC

Abstract: Current observations suggest that the Gamma-ray emission of
blazars may take place several pc from the central black hole, where
the anticipated energy density of external photons is low.  In this
case, the dominant Gamma-ray emission mechanism is Synchrotron-self
Compton (SSC).

Here, we investigate the importance of second-order SSC (SSC2), a
process in which SSC photons are upscattered by the same population of
relativistic electrons that produced the synchrotron and SSC
emission. We study the case in which the maximum electron energy is
independent of the physical conditions in the source and the more
physically motivated case where the physical conditions in the source
affect the maximum energy achieved by particle acceleration.

We show that SSC2 is a viable, and possibly dominant spectral
component that naturally produces superquadratic variations of the GeV
emission relative to those observed in the synchrotron component. We
also show that the rarely seen cubic variations, if interpreted as
SSC2 emission, impose significant lower limits (Lorentz factors >100)
on the emitting plasma.

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Name: Talvikki Hovatta

Title: Faraday Rotation in the MOJAVE blazar jets

Authors: Talvikki Hovatta, Caltech and Purdue University
Matthew L. Lister, Purdue University
Margo F. Aller, University of Michigan
Hugh D. Aller, University of Michigan
Daniel C. Homan, Denison University
Yuri Y. Kovalev, Astro Space Center of Lebedev Physical Institute and
Alexander B. Pushkarev, Pulkovo Observatory and Crimean Astrophysical
Observatory
Tuomas Savolainen, Max Planck Institute for Radioastronomy

Abstract: We have conducted a survey of Faraday rotation in a sample
of 191 compact radio-loud AGNs as part of the MOJAVE (Monitoring of
Jets in Active galactic nuclei with VLBA Experiments) project. The
observations were carried out with the VLBA at 8.1, 8.4, 12.1 and 15.3
GHz over 12 epochs in 2006. We detect sufficiently strong linear
polarization in 159 out of 211 observations to calculate the rotation
measure values, resulting in a large enough sample for statistical
analysis of the Faraday rotation in blazars.  We will present an
overview of the results from this large survey and show examples of
individual sources. We find the cores of the AGNs to have higher
rotation measures than the jets and also indications that the rotation
measures in quasars are larger than in BL Lac objects. Additionally,
we performed detailed simulations to find a reliable way to estimate
the significance of transverse rotation measure gradients, thought to
be a signature of large scale helical magnetic fields. We find a
significant transverse rotation measure gradient in four quasars (3C
273, 3C 454.3, CTA 102 and 4C 39.25) and indications of gradients in
four others. In 3C 273 and 3C 454.3 the gradient could be consistent
with a helical field while in 4C 39.25 it could be due to interaction
with the intergalactic medium. In CTA 102 we need more detailed
observations to confirm the gradient and its origin. 117 of our
sources are included in the 2FGL catalog and we detect rotation
measure values in 111 out of 129 maps. Of the 74 sources that are not
in the 2FGL catalog we detect RM in 48 out of 82 maps. The median RM
values of the 2FGL sources do not differ significantly from the
non-LAT-detected sources although it is interesting that three of the
four sources with significant rotation measure gradients are sources
that have shown large gamma-ray flares.

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Title: Parsec-Scale Jet Behavior of the Quasar 3C454.3 during the High
Gamma-Ray States in 2009 and 2010.

Authors: S.G. Jorstad, A.P. Marscher (Boston U., USA), P.S. Smith
(Steward Obs., USA), V.M. Larionov (St.Petersburg U., Russia),
and M. Gurwell(CfA, USA)

Abstract: We analyze total and polarized intensity images of the
quasar 3C454.3 obtained monthly with the VLBA at 43 GHz within the
ongoing Boston U. monitoring program of gamma-ray blazars started in
June 2007. These data are supplemented by VLBA observations performed
during intense campaigns of 2 week duration when the quasar was
observed 3-4 times per campaign. We find a strong increase of activity
in the parsec-scale jet of the quasar during high gamma-ray states in
Autumn 2009 and Autumn 2010. We detect new superluminal knots
associated with both events and compare their kinematic parameters. We
analyze optical photometric and polarimetric data along with X-ray
light curves collected over the periods of the $gamma$-ray$outbursts and outline similarities and differences in variations across wavelengths. We discuss the locations in the jet where high gamma-ray fluxes occur. This research was supported in part by NASA grants NNX08AV65G, NNX08AV61G, NNX09AT99G, and NNX09AU10G, and NSF grant AST-0907893. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the NSF, operated under cooperative agreement by Associated Universities, Inc. ------------------------------------------------------------------------ Name: Demosthenes Kazanas Title: AGN Unification and the Gamma-Ray Spectra of Fermi Blazars Authors: Demosthenes Kazanas (NASA/GSFC), Keigo Fukumura (NASA/GSFC-CRESST), Markos Georganopoulos (UMBC), Sean Scully (JMU), Floyd Stecker (NASA/GSFC) Abstract: The recent Fermi LAT-driven multiwavelength blazar studies have indicated that that in many objects the observed$gamma-$rays require, besides the synchrotron photons, also an additional contribution to the Compton process by photons external to that of the moving plasma (External Compton -- EC). This additional photon component has been attributed to emission by the clouds of the AGN Broad Line Region (BLR). However, in many cases the gamma ray emission takes place at distances larger than that of the traditionally considered BLR size. We propose that the external photons needed to account for the blazar gamma-ray spectra are supplied by MHD winds off the AGN accretion disks with radial density profiles n(r) ~ 1/r. These winds span several (5-6) decades in radius and it has been proposed that these actually are the "molecular torii" invoked in AGN unification. Winds with this specific density dependence were employed successfully to account for the Seyfert Warm Ab sorber X-ray properties and their infrared and far-infrared spectra. We show how these same winds can affect the blazar gamma-ray emission and their influence on shaping the so called "blazar sequence". ------------------------------------------------------------------------ Name: Stefan Larsson Title: Statistical analysis of multiwavelength light curves Authors: Stefan Larsson, Stockholm University Abstract: Since its launch in 2008 the Fermi Large Area Telescope provides regular monitoring of a large sample of gamma-ray sources on time scales from hours to years. Together with observations at other wavelengths it is now possible to study variability and correlation properties in a much more systematic and detailed way than ever before. I will describe some of the statistical methods and tools that have been, or can be, used to characterize variability and to study the relation between multiwavelength light curves. Effects and limitations due to time sampling, measurement noise, non-stationarity etc will be illustrated and discussed. ------------------------------------------------------------------------ Name: Jonathan Leon-Tavares Title: The (sub-)mm and gamma-ray connection in northern blazars Authors: J. Leon-Tavares (1) E. Valtaoja (2) A. Lahteenmaki (1) M. Tornikoski (1) (1) Metsahovi Radio Observatory (2) Tuorla Observatory Abstract: Thanks to the co-existence of Planck and Fermi satellites, we explore the connection between the (sub-)mm and gamma-ray emission in a sample of northern blazars. First, based on the results from Planck Collaboration et al. (2011) we explore emerging trends between the mm/submm spectral shapes and gamma-ray brightness. Second, using a sample of 45 northern extragalactic radio sources, Leon-Tavares et al. (2011) have presented evidence that the most intense gamma-ray flares are produced in the same disturbances that produce the mm outburst. We will discussed these results and their implications to the origin of the gamma-ray emission in blazars. Leon-Tavares et al. 2011, A&A, 532, 146 Planck Collaboration et al. 2011, A&A accepted, arXiv:1101.2047 ------------------------------------------------------------------------ Name: Justin Linford Title: Parsec-Scale Radio Properies of Gamma-ray Emitting Blazars Authors: Justin D. Linford (UNM) Gregory B. Taylor (UNM) Roger W. Romani (Stanford) Joseph F. Helmboldt (NRL) Anthony C.S. Readhead (Caltech) Rodrigo Reeves (Caltech) Joseph L. Richards (Caltech) Abstract: The parsec-scale radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been investigated using observations with the Very Long Baseline Array (VLBA). Comparisons between LAT and non-LAT detected samples were made using both archival and contemporaneous data. In total, 244 sources were used in the LAT-detected sample. This very large, radio flux-limited sample of active galactic nuclei (AGN) provides insights into the mechanism that produces strong gamma-ray emission. It has been found that LAT-detected BL Lac objects are very similar to the non-LAT BL Lac objects in most properties, although LAT BL Lac objects may have longer jets. The LAT flat spectrum radio quasars (FSRQs) are significantly different from non-LAT FSRQs and are likely extreme members of the FSRQ population. Archival radio data indicated that there was no significant correlation between radio flux density and gamma-ray flux, especially at lower flux levels. However, contemporaneous observations showed a strong correlation. Most of the differences between the LAT and non-LAT populations are related to the cores of the sources, indicating that the gamma-ray emission may originate near the base of the jets (i.e., within a few pc of the central engine). There is some indication that LAT-detected sources may have larger jet opening angles than the non-LAT sources. Strong core polarization is significantly more common among the LAT sources, suggesting that gamma-ray emission is related to strong, uniform magnetic fields at the base of the jets of the blazars. Observations of sources in two epochs indicate that core fractional polarization was higher when the objects were detected by the LAT. Included in our sample are several non-blazar AGN such as 3C84, M82, and NGC 6251. ------------------------------------------------------------------------ Name: Matthew Lister Title: Gamma-ray and parsec-scale jet properties of a complete sample of blazars from the MOJAVE program Authors: M. Lister on behalf of the LAT and MOJAVE collaborations Abstract: We investigate the Fermi LAT gamma-ray and 15 GHz VLBA radio properties of a joint gamma-ray- and radio-selected sample of AGNs obtained during the first 11 months of the Fermi mission (2008 Aug 4 - 2009 Jul 5). Our sample contains the brightest 173 AGNs in these bands above declination -30 during this period, and thus probes the full range of gamma-ray loudness (gamma-ray to radio band luminosity ratio) in the bright blazar population. The latter quantity spans at least four orders of magnitude, reflecting a wide range of spectral energy distribution (SED) parameters in the bright blazar population. The BL Lac objects, however, display a linear correlation of increasing gamma-ray loudness with synchrotron SED peak frequency, suggesting a universal SED shape for objects of this class. The synchrotron self-Compton model is favored for the gamma-ray emission in these BL Lacs over external seed photon models, since the latter predict a dependence of Compton dominance on Doppler factor that would destroy any observed synchrotron SED peak - gamma-ray loudness correlation. The high-synchrotron peaked (HSP) BL Lac objects are distinguished by lower than average radio core brightness temperatures, and none display large radio modulation indices or high linear core polarization levels. No equivalent trends are seen for the flat-spectrum radio quasars (FSRQ) in our sample. Given the association of such properties with relativistic beaming, we suggest that the HSP BL Lacs have generally lower Doppler factors than the lower-synchrotron peaked BL Lacs or FSRQs in our sample. ------------------------------------------------------------------------ Name: Benoit Lott Title: The Second Catalog of AGNs detected by the Fermi-LAT Authors: Benoit Lott (CENBG, France) on behalf of the Fermi-LAT collaboration Abstract: The properties of the AGNs detected by the Fermi-LAT after 2 years of operation and composing the 2LAC catalog will be reviewed. ------------------------------------------------------------------------ Name: Alan Marscher Title: Relation between Events in the Millimeter-wave Core and Gamma-ray Outbursts in Blazars Authors: A.P. Marscher and S.G. Jorstad (Boston U.) Abstract: We report results from our program of monitoring 33 gamma-ray detected blazars with the VLBA at 43 GHz. Comparison of the epochs when new superluminal knots pass through the mm-wave core with times when gamma-ray flares observed by the Fermi LAT occur reveals a number of cases when the events are simultaneous within the uncertainties. However, in other blazars the core brightens at mm wavelengths during a gamma-ray flare, but no bright new knot is apparent. In addition, some gamma-ray flares occur before passage of a knot through the core. A fraction of the blazars in our sample show little or no relation between mm-wave and gamma-ray events. The gamma-ray emission therefore appears to occur in multiple sites in different blazars, and sometimes within a given object. This conclusion has important implications regarding the inference of the physical conditions under which high-energy emission occurs in the relativistic jets of blazars. This research was supported in part by NASA grants NNX08AV65G, NNX08AV61G, NNX09AT99G, NNX09AU10G, NNX10AO59G, and NNX11AQ03G, and by NSF grant AST-0907893. ------------------------------------------------------------------------ Name: Walter Max-Moerbeck Title: OVRO 40m blazar monitoring program: Understanding the relationship between 15 GHz radio variability properties and gamma-ray activity in blazars Authors: W. Max-Moerbeck, J.L. Richards, V. Pavlidou, T. Hovatta, O.G. King, T.J. Pearson, A.C.S. Readhead, R. Reeves, M.C. Shepherd. California Institute of Technology, Pasadena, CA, USA Abstract: A large sample of known and likely gamma-ray blazars has been monitored twice per week since late 2007 at 15 GHz with the Owens Valley Radio Observatory (OVRO) 40-meter Telescope. The sample contains about 1600 sources, including the initial sample of all the 1158 sources above declination -20 degrees from the Candidate Gamma-Ray Blazar Survey (CGRaBS) plus all the blazars associated with Fermi-LAT detections as released in the Fermi source catalogs. Using statistical likelihood analyses, we compare the variability amplitude for various sub-populations within our sample. These include comparisons of gamma-ray-loud versus quiet objects, BL Lac objects versus flat-spectrum radio quasars, and a study of the variability amplitude trend with redshift. To learn about the location of the gamma-ray emission region we study the significance of peaks in the radio/gamma-ray cross-correlation using Monte Carlo simulations. First results for 52 sources with data from both the hi gh-confidence Fermi Large Area Telescope Bright AGN Sample and the first 2 years of our monitoring program show that only 7 show significant cross-correlations at the 3-sigma level. An extension of this to a larger sample and longer light curves is underway and preliminary results are presented. We also describe KuPol, the new digital Ku-band receiver being constructed for the 40-meter telescope. This new receiver will provide total intensity and linear polarization measurements over the 12-18 GHz band, with 16 MHz spectral resolution. The polarization data will provide important clues about the magnetic field configuration in the radio emission region. ------------------------------------------------------------------------ Name: Eileen Meyer Title: Breaking the Blazar Sequence: A new view of Radio Loud AGN Unification Authors: Meyer, Eileen T. (Rice University) Fossati, Giovanni (Rice University) Georganopoulos, Markos (University of Maryland, Baltimore County) Lister, Matthew L. (Purdue University) Abstract: In recent work, we have identified two sub-populations of radio-loud AGN which appear to be distinguished by jet structure, where low-efficiency accreting systems produce 'weak' jets which decelerate more rapidly than the 'strong' jets of black holes accreting near the Eddington limit. The two classes are comprised of: (1) The weak jet sources, corresponding to FR I radio galaxies, having a decelerating or spine-sheath jet with velocity gradients, and (2) The strong jet sources, having fast, collimated jets, and typically displaying strong emission lines. The dichotomy in the vp-Lp plane can be understood as a "broken power sequence" in which jets exist on one branch or the other based on the particular accretion mode (Georganopoulos 2011).We suggest that the intrinsic kinetic power (as measured by low-frequency, isotropic radio emission), the orientation, and the accretion rate of the SMBH system are the the fundamental axes needed for unification of radio-loud AGN by studying a well-characterized sample of several hundred Fermi-detected jets. Finally, we present very recent findings that the most powerful strong jets produce gamma-rays by external Compton rather than SSC emission, placing the dissipation region in these strong jets at a radius inside the BLR and/or molecular torus (Meyer 2011). ------------------------------------------------------------------------ Name: Cornelia Mueller Title: The TANAMI Program: Southern-Hemisphere AGN on (Sub-)Parsec Scales Author: Cornelia Mueller, Matthias Kadler, Roopesh Ojha, Joern Wilms on behalf of the TANAMI team Abstract: The TANAMI VLBI monitoring program provides bi-monthly, dual-frequency, parsec scale monitoring of AGN in the southern third of the sky using the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. Supporting programs provide multiwavelength coverage of \textsl{Fermi}/LAT sources, in order to construct simultaneous broadband SEDs, as well as rapid follow-up of high energy flares. After a brief description of this program and its current status we will present some results including those from the highest resolution image of an AGN (the nearby radio galaxy Centaurus~A) ever made. With the first epoch TANAMI dual-frequency images at an angular resolution of about$0.7 \times 0.4$\,mas we can construct the best resolved spectral index map of the sub-parsec scale jet-counterjet system of Cen~A. We can identify multiple possible sites as the origin of$\gamma$-ray emission detected by the \textsl{Fermi}/LAT. The multi-epoch analysis based on the first four 8.4\,GHz observations reveals a very complex kinematical behaviour when tracking individual components of lightday-scale size. ----------------------------------------------------------------------- Name: Nina Nowak Title: Radio-to-Gamma Ray Monitoring of Mkn 421 and Mkn 501: Source Variability Authors: N. Nowak(1), D. Paneque(1), U. Barres de Almeida(1), N. Strah(2), D. Tescaro(3) (1) MPI fuer Physik, 80805 Munich, Germany (2) Technische Universitaet Dortmund, 44221 Dortmund, Germany (3) Universita di Siena and INFN Pisa, 53100 Siena, Italy Abstract: We present first results from simultaneous multifrequency observations of the high-synchrotron-peaked BL Lac objects Mrk 421 and Mrk 501 during 4.5 months in 2009. This is part of a multi-year and multi-instrument programme including VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, VERITAS and many other collaborations and instruments. This extensive radio to TeV data set provides unprecedented temporal and energy coverage of the two sources during a phase of low activity. The SEDs of both objects are very similar and can be described by a standard one-zone synchrotron self-Compton model. In this talk we will report on the multifrequency lightcurves, variability and correlations, and will evaluate these results in the framework of commonly used emission models. ------------------------------------------------------------------------ Name: Eduardo Ros Title: High-resolution monitoring of parsec-scale jets in the Fermi era Authors: Eduardo Ros Universitat de ValËncia, Spain & Max-Planck-Institut f¸r Radioastronomie, Germany Abstract: I will review the present observational efforts to study parsec-scale radio jets in active galactic nuclei by means of very-long-baseline interferometry (VLBI) as related to the new window to the Universe opened by Fermi. I will describe the goals and achievements of those radio studies, which aim to probe the emission properties, morphological changes and related kinematics, magnetic fields from the linear and circular polarization, etc., and I will put those in the context of the radio--gamma-ray connection. ------------------------------------------------------------------------ Name: Shane O'Sullivan Title: Spectropolarimetric Properties of the Giant Radio Lobes of Centaurus A Authors: Shane O'Sullivan, Ilana Feain, Naomi McClure-Griffiths, Tim Cornwell, Ron Ekers, Ettore Carretti (CSIRO Astronomy and Space Science, ATNF, Sydney) Abstract: We present a new study of the polarization and Faraday rotation measure (RM) properties of the giant lobes (projected linear scale: ~500 kpc) of our nearest radio galaxy, Centaurus A. Our analysis is based on spectropolarimetric observations with the Australia Telescope Compact Array (ATCA) and the Parkes 64 m single dish at 1.4 GHz. The proximity of Centaurus A provides us with the ultimate laboratory for studying the physical processes that form these giant lobes and the particle acceleration that illuminates the structure. We describe several new, previously undiscovered features amongst the complex filamentary structures seen throughout the lobes. We also discuss our results in the context of the recent detection of gamma-ray emission from the giant lobes with the Fermi satellite and the implications for the magnetic field strength and particle density in the lobes. ------------------------------------------------------------------------ Name: Paolo Padovani Title: A simplified view of blazars: why BL Lacertae is actually a quasar in disguise Authors: P. Padovani (ESO), P. Giommi, G. Polenta, S. Turriziani, V. D'Elia (ASDC), S. Piranomonte (INAF) Abstract: We propose a scenario where blazars are classified as flat-spectrum radio quasars (FSRQs), BL Lacs, low synchrotron, or high synchrotron peaked objects according to a varying mix of the Doppler boosted radiation from the jet, the emission from the accretion disk, the broad line region, and the light from the host galaxy. We test this new approach, which builds upon unified schemes, using extensive Monte Carlo simulations and show that it can provide simple answers to a number of long-standing issues including, amongst others, the different cosmological evolution of BL Lacs selected in the radio and X-ray bands, the larger synchrotron peak frequency (nu_peak) values observed in BL Lacs, the fact that high synchrotron peaked blazars are always of the BL Lac type, and the existence of FSRQ/BL Lac transition objects. Objects so far classified as BL Lacs on the basis of their observed weak, or undetectable, emission lines are of two physically different classes: intrinsically weak lined objects, more common in X-ray selected samples, and heavily diluted broad lined sources, more frequent in radio selected samples, which explains some of the confusion in the literature. We also show that strong selection effects are the main cause of the diversity observed in radio and X-ray samples, and that the correlation between luminosity and nu_peak, that led to the proposal of the blazar sequence'', is also a selection effect. ------------------------------------------------------------------------ Name: Jeremy S Perkins Title: Cherenkov and Jansky: Our Understanding of AGN at the Highest Energies Authors: Jeremy S Perkins (UMBC/CRESST/GSFC) on behalf of the VERITAS and Fermi LAT Collaborations Abstract: The radio galaxy M87 has been the subject of some of the most successful radio and gamma-ray multiwavelength campaigns. These campaigns have included many of the major ground and space based gamma-ray telescopes and span decades of energy. The size and proximity (~16Mpc) of M87 makes it a unique laboratory for the study of AGN jet substructure and the morphology of non-thermal emission processes. A recent flare in 2010, observed at very high energies (E > 100 GeV) with VERITAS, triggered the most recent campaign. Results from this campaign will be presented along with a review of past campaigns ------------------------------------------------------------------------ Name: Leonid Petrov Title: Parsec-scale study of Fermi sources Authors: Leonid Petrov, ADNET Systems/NASA GSFC Yury Kovalev, ASC Lebedev, MPIfR Abstract: It was established that over 60% of 2FGL objects outside of the Galactic plane have associations with relatively bright compact extragalactic radio sources detected in all-sky VLBI surveys. In order to eliminate sampling bias, we observed with VLBA+GBT radio weak AGN associations of Fermi detections with no prior knowledge on their parsec-scale properties and got almost 100% detection rate. We determined flux densities from parsec scales, compactness and other characteristics of observed sources and used the full Fermi-VLBI sample to perform population analysis of blazars. We derived VLBI positions of all Fermi associations with a sub-mas accuracy level and evaluated random and systematic position errors of the 2FGL catalogue. ------------------------------------------------------------------------ Name: Parisa Roustazadeh Title: Synchrotron Emission from VHE Gamma-Ray Induced Pair Cascades in AGN Environment Authors: Parisa Roustazadeh and Markus Boettcher Ohio University, Athens, OH 45701 Abstract: The discovery of very-high-energy (VHE, E > 100 GeV) gamma-ray emission from intermediate- and low-frequency peaked blazars suggests that gamma-gamma absorption and pair cascading might occur in those objects. We demonstrate that Compton emission from VHE gamma-ray induced pair cascades, deflected by moderate magnetic fields, can explain the Fermi fluxes and spectra of the radio galaxies Cen A and NGC 1275. We demonstrate that the magnetic field can not be determined from a fit of the cascade emission to the gamma-ray spectrum alone, and the degeneracy can only be lifted if the synchrotron emission from the cascades is observed as well. We point out that the cascade synchrotron emission may produce spectral features reminiscent of the big blue bump observed in the spectral energy distributions of several blazars, and apply this idea to 3C 279. ------------------------------------------------------------------------ Name: Tuomas Savolainen Title: When Fermi met Jansky... - A summary of the Bonn meeting Authors: Tuomas Savolainen (Max-Planck-Institut f. Radioastronomie) Abstract: The previous meeting on radio - gamma-ray connection in active galactic nuclei, appropriately named "Fermi meets Jansky", was organized in Bonn last year. In this talk I will attempt to summarize the scientific content of the "Fermi meets Jansky" workshop and to give a (subjective) review of its highlights. In order to set the stage for today's meeting, I will also give an account of the major open questions that were debated in Bonn. ------------------------------------------------------------------------ Name: Greg Taylor Title: Imaging at Both Ends of the Spectrum: the Long Wavelength Array and Fermi Authors: Greg Taylor (UNM) on behalf of the LWA Collaboration Abstract: The Long Wavelength Array (LWA) will be a new multi-purpose radio telescope operating in the frequency range 10-88 MHz. Scientific programs include pulsars, supernova remnants, general transient searches, radio recombination lines, solar and Jupiter bursts, investigations into the "dark ages" using redshifted hydrogen, and ionospheric phenomena. Upon completion, LWA will consist of 53 phased array "stations" distributed accross a region over 400 km in diameter. Each station consists of 256 pairs of dipole-type antennas whose signals are formed into beams, with outputs transported to a central location for high-resolution aperture synthesis imaging. The resulting image sensitivity is estimated to be a few mJy (5sigma, 8 MHz, 2 polarizations, 1 h, zenith) from 20-80 MHz; with angular resolution of a few arcseconds. Additional information is online at http://lwa.unm.edu. Partners in the LWA project include LANL, JPL, NRAO, NRL, UNM, NMT, and Virginia Tech. The full LWA will be a powerful instrument for the study of particle acceleration mechanisms in AGN. Even with the recently completed first station of the LWA, called "LWA1", we can begin spectral studies of AGN radio lobes. These can be combined with Fermi observations. Furthermore we have an ongoing project to observe Crab Giant Pulses in concert with Fermi. In addition to these pointed studies, the LWA1 images the sky down to declination$-\$30 degrees daily.  This is quite
complimentary to Fermi's daily images of the sky.

------------------------------------------------------------------------
Name: Eleonora Torresi

Title: The X-ray view of FR-I and FR-II radio galaxies detected by
Fermi-LAT

Authors: Eleonora Torresi INAF/IASF-Bologna, Italy
Paola Grandi INAF/IASF-Bologna, Italy

Abstract: We study the X-ray properties of FRI and FRII radio galaxies
having a Fermi-LAT counterpart, and belonging to well-studied radio
catalogs, i.e. 3CR, 3CRR, 2Jy and Molonglo samples. There is evidence
that the LAT instrument preferentially detects FRIs. The discrepancy
between FRI and FRII gamma detection rates does not seem to be related
to FRIIs˘ larger distances. Different jet properties might be a more
reliable interpretation and X-rays represent a very useful tool to
explore this possibility.  Indeed, they allow to investigate the
nuclear region, where the jet is produced, and the environment, where
it propagates.  High-resolution X-ray images provide information on
the extended (kpc scale) warm/hot gas, if present, and moderate energy
resolution spectra can be used to verify the presence (absence) of
signatures witnessing efficient (unefficient) accretion disks (for
example the iron Ka line).

------------------------------------------------------------------------
Name: Valerio Vittorini

Title: Some considerations on the last flare of 3C 454.3

Authors: Valerio Vittorini on behalf of AGILE Team

IASF INAF via Fosso del cavaliere 100, I-00133 Rome

Abstract: We rewiev the last giant flare of 3C 454. The monthly light
curves on different bands show an intriguing behaviour: in particular,
optical and gamma-ray bands appear not univocally correlated, arguing
for a complex mechanism in the production of the flare.

------------------------------------------------------------------------
Name: Robert Wagner

Title: Recent MAGIC observations of active galactic nuclei: Studies in
the decisive E>50 GeV region

Authors: R. M. Wagner for the MAGIC Collaboration

Abstract: MAGIC, a stereoscopic imaging air Cherenkov telescope system
with two 17-m diameter reflectors, is sensitive to gamma-rays from
some ten GeV (the lowest energy threshold of such telescope systems)
up to some TeV, which enables the study of gamma-ray emission right
above the energy regime to which Fermi-LAT is sensitive. In this
energy region, source-intrinsic high-energy cutoffs due to, e.g.,
Klein-Nishina suppression, but also absorption of gamma-rays by the
extragalactic background light (EBL) take place and make it an energy
window of utmost importance for AGN studies. We report on recent AGN
observations that have been performed with the MAGIC telescopes,
emphasizing multi-wavelength observations; studies of non-blazar type
AGN; and studies of particularly distant blazars with z>0.4 (3C 279,
PKS 1222+21), in which particularly the observed fast variability
challenges conventional particle acceleration models and the observed
extension of their spectra supports a low EBL density.

------------------------------------------------------------------------
Name: Andreas Zech

Title: AGN physics with the Cherenkov Telescope Array

Authors: Andreas Zech (for the CTA collaboration) LUTH, Observatoire
de Paris, CNRS, UniversitÈ Paris Diderot ; 5 Place Jules Janssen,
92190 Meudon, France.

Abstract: The Cherenkov Telescope Array (CTA), currently in its
preparatory phase, will be the first open observatory for very high
energy gamma rays. The international consortium behind CTA aims to
build two large arrays of Cherenkov telescopes in the Northern and
Southern hemispheres with a performance that will be significantly
improved compared to the current generation of arrays, such as
H.E.S.S., MAGIC and VERITAS.  Its increased sensitivity and energy
range will give CTA access to a large population of AGNs not yet
detected at very high energies and provide much greater details on
known TeV sources. While the low end of the CTA energy coverage will
close the current gap with the Fermi band, its high energy coverage,
up to 100 TeV, will open a new window on the sky, help us understand
the intrinsic shape of the hardest blazar spectra and further
constrain the distribution of the extragalactic background light.


## Poster Abstracts

Name: Michael Dutka

Title: Multi-wavelength Observations of PKS 2142-75 during an Active
Gamma-Ray State

Authors: M. Dutka (Catholic University of America), R. Ojha
(NASA/Goddard Space Flight Center), J. Finke (Naval Research
Laboratory), K. Pottschmidt (NASA/Goddard Space Flight Center),
J. Blanchard (University of Tasmania), R. Nesci (University La
Sapienza), J. Lovell (University of Tasmania), M. Kadler (University
of Wurzburg), G. Tosti (University of Perugia), T. Pursimo (Nordic
Optical Telescope), J. Wilms (University of Erlangen-Nuremberg)

Abstract: PKS 2142-758 is a flat spectrum radio quasar at a redshift
of 1.139 (Jauncey et al., 1978 ApJ, 219, L1) which has been detected
in an active state by Fermi/LAT twice since its first flare detection
on April 4th, 2010, when it reached a flux of (1.1 +- 0.3)* 10 ^ -6 ph
cm^-2 s^-1. This flux represented more than an order of magnitude
increase over its quiescent flux. Since the initial flare, this source
has been found with daily TS > 25 by Fermi/LAT in a period ranging
from October to November of 2010 and another period ranging from July
to August of 2011. During the latest flaring period a multi wavelength
campaign was carried out using the Ceduna radio telescope, the TANAMI
VLBI Array, Swift, and REM.  We present results from these
observations and discuss their implications for understanding the
flaring behavior of AGN

------------------------------------------------------------------------
Name: Elizabeth Ferrara

Authors: Elizabeth Ferrara for the Fermi/LAT Collaboration

Abstract:The gamma-ray sky as seen by the Fermi-LAT after 2 years of
observations contains almost 1900 sources. Yet nearly a third of these
sources show no clear association with an object belonging to a known
gamma-ray emitting class. To investigate the nature of these sources,
a number of multiwavelength investigations have been initiated to
observe the most promising sources in TeV, X-ray, optical, and radio
wavebands. In addition, archival searches and correlations with other,
less-likely source catalogs provide additional insights into
possibilities for the origin of these sources. We discuss the
gamma-ray properties of these mystery sources, the methods being used
to investigate them, and summarize the results to date of these
various initiatives.

------------------------------------------------------------------------
Name: Markos Georganopoulos

Title: Radio loud AGN unification: jet power, orientation, and  accretion mode

Authors: Markos Georganopoulos, UMBC, NASA/GSFC
Eileen Meyer, Rice University
Giovanni Fossati, Rice University
Matt Lister, Purdue University

Abstract: Motivated by recent work (Meyer et al. 2011), we examine the
consequences of the following hypothesis: the observed properties of
extragalactic jets are a function of the jet kinetic power, accretion
mode (efficiently or inefficiently radiating accretion disk), and jet
orientation. Following Ghisellini et al. (2009), we adopt the
theoretical prediction (Narayan et al. 1997) that the transition from
radiatively inefficient to efficient accretion takes place at a
fraction ~0.001-0.01 of the Eddington mass accretion rate.  We also
assume, based on previous work, that contrary to powerful blazars,
X-ray peaking blazars exhibit velocity gradients in the plasma
responsible for the blazar emission. We show that the implications of
this scheme are compatible with trends we find in the M11 sources, and
with the picture emerging from Fermi observations.

------------------------------------------------------------------------
Name: Manasvita Joshi

Title: Multiwavelength Spectral Studies Of Fermi-LAT Blazar

Authors: Manasvita Joshi, A. Marscher, S. Jorstad (Boston U.),
I. Agudo (Boston U. & IAA), V. Larionov (St. Petersburg State U.),
M. Aller (U. Michigan), M. Gurwell (SAO), A. Lahteenmaki (Metsahovi
Radio Obs.), & Paul Smith (Steward Observatory, University of Arizona)

Abstract: We present the most up-to-date gamma-ray, x-ray, and optical
(both photometric and polarimetric in the R band) lightcurves of
Fermi-LAT blazar, 3C279, which is part of the Boston University
multiwaveband polarization monitoring program. The data have been
compiled from observations with Fermi, Swift, RXTE, the VLBA, and
various ground-based optical and radio telescopes starting in August
2008. We simulate the dynamic spectral energy distributions (SEDs) of
3C279, in quiescent and flaring states, within the framework of a
multi-slice, time-dependent leptonic jet model for blazars, with
radiation feedback, in the internal shock scenario. We use the
physical jet parameters obtained from the VLBA monitoring to guide our
modeling efforts. We discuss the role of intrinsic parameters and the
interplay between synchrotron and inverse Compton radiation processes
responsible for producing the resultant SEDs.

This research was supported in part by NASA through Fermi grants
NNX10AO59G, NNX08AV65G, and NNX08AV61G, NASA through Swift grants
NNX09AR11G, NNX10AL13G, and NNX10AF88G, and by NSF grant AST-0907893.

------------------------------------------------------------------------

Title: APEX sub-mm monitoring of gamma-ray blazars

Authors: S. Larsson (Stockholm University, Sweden), L. Fuhrmann,
A. Weiss, E. Angelakis, T.P. Krichbaum, N. Marchili, I. Nestoras,
J.A. Zensus (MPIfR, Bonn, Germany), M. Axelsson, D. Nilsson, F. Ryde
(KTH, Stockholm, Sweden), L. Hjalmarsdotter (Sternberg Observatory,
Moscow, Russia), A. Lundgren (ESO, Chile)

Abstract: A sample of about 40 gamma-ray blazars have been monitored
at sub-mm wavelengths over a time period of 3 to 4 years.
Observations were made with the LABOCA detector on the
ESO/MPI/Swedish APEX telescope in Chile. The observations
have been used to study the sub-mm variability properties
and how these relate to source types and gamma-ray characteristics
as seen by Fermi LAT.

------------------------------------------------------------------------
Name: Rocco Lico

Title: VLBA monitoring of Mrk 421 at 15 and 22 GHz during 2011

Authors: R. Lico (Univ. of Bologna & INAF/IRA),
M. Giroletti, M. Orienti, G. Giovannini (INAF/IRA),
B. Cotton (NRAO),
P. Edwards (ATNF),
L. Fuhrmann, T. Krichbaum, K. Sokolovsky (MPIfR),
S. Jorstad, A. Marscher (Boston Univ.),
M. Kino (NAOJ),
Y. Kovalev (Lebedev),
D. Paneque (Stanford),
M.A. Perez-Torres (IAA),
G. Piner (Whittier)

Abstract: We present a preliminary analysis of new high resolution
radio observations of the nearby TeV blazar Markarian 421
(z=0.031). We consider data obtained with the Very Long Baseline Array
(VLBA) at 6 epochs (one observation per month from January through
June 2011) at 15 and 22 GHz. We investigate the inner jet structure,
on parsec scale, trough the study of model-fit components for each
epoch. Almost all components seem to be stationary. In particular,
from fits at 22 GHz we find indications of a limb brightened
structure, that will be further discussed from future analysis of data
at 43 GHz. This study is part of a most ambitious multifrequency
campaign, with observations in sub-mm (SMA), in optical/IR (GASP), in
UV/X-ray (Swift, RXTE, MAXI), and in γ ray (Fermi-LAT, MAGIC,
VERITAS). The aim is to try to shine a light definitively on questions
such as the nature of radiating particles, the connection between
radio and γ emission, the location of emitting r egions and the
origin of the flux variability.

------------------------------------------------------------------------
Name: Elisabetta Liuzzo

gamma-ray data.

Authors: E. Liuzzo, G. Giovannini, M. Giroletti

Abstract: To study a statistical properties of different classes of
radio sources, we defined and observed the Bologna Complete Sample
(BCS). The BCS is a complete sample of 95 objects that is unbiased
with respect to the orientation of the nuclear relativistic jet being
selected from low-frequency samples. Moreover, it is composed by
nearby (z<0.1) radio galaxies that are well studied targets with
literature kiloparsec data.  For all of them, we collected parsec
scale information asking also new VLBI observations. Statistical
results on their properties in radio band are presented. From the
estimates of the doppler factor and wiewing angles, we discuss the
connection with the available gamma-ray data.  Finally, we show how
future observations with Fermi could reveal new important detections
of some of the BCS sources.

------------------------------------------------------------------------
Name: Francesco Massaro

Title: Infrared colors of the gamma-ray detected blazars

Authors: presenting author: G. Tosti
R. D'Abrsuco (Harvard - Smithsonian Astrophysical Observatory)
F. Massaro (Stanford University)
M. Ajello (SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology)
J.E. Grindlay (Harvard - Smithsonian Astrophysical Observatory)
H. A. Smith (Harvard - Smithsonian Astrophysical Observatory)
G. Tosti (Dipartimento di Fisica, Universita degli Studi di Perugia)

Abstract: Blazars constitute the most interesting and enigmatic class
of extragalactic gamma-ray sources dominated by non-thermal emission.
We present how the WISE infrared data make possible to identify a
distinct region of the [3.4]-[4.6]-[12] micron color-color diagram
where the sources dominated by the thermal radiation are separated
from those dominated by non-thermal emission, in particular the blazar
population.  We show the relation between the infrared and gamma-ray
emission for a selected sample of ROMA-BZCAT blazars associated with
Fermi sources, for which WISE archival observations are available.
The selected blazars lie on the WISE blazar Strip, covering a tighter
region of the infrared color-color plots than the overall blazar
population.  We then search for a correlation between the IR and
gamma-ray spectral indices expected in the SSC and EC
frameworks. Finally, we estimate the ratio between their gamma-ray and
infrared fluxes, a surrogate of the ratio of powers between the
inverse Compton and the synchrotron SED components, a parameter that
is useful to test these different emitting scenarios.

------------------------------------------------------------------------
Name: Monica Orienti

Title: High resolution radio observations of gamma-ray emitting Narrow
Line Seyfert 1s

Authors: M. Orienti (INAF-IRA Bologna), F. D'Ammando (INAF-IRA
Bologna), M. Giroletti (INAF-IRA Bologna)

Abstract: The detection by Fermi-LAT of gamma-ray emission from
radio-loud Narrow-Line Seyfert 1s indicates that relativistic jets do
not form only in blazars and radio galaxies. Despite a spectral energy
distribution similar to blazars, their physical characteristics are
quite different: lower black hole masses, generally higher accretion
rates, and likely hosted in spirals. Furthermore, their radio
properties make the interpretation of these objects even more
puzzling. The radio emission is very compact, not exceeding the parsec
scales, and it is not significantly variable, as also found in the
population of young radio sources.  In this talk I will present high
resolution VLBA observations of the three radio-loud NLSy1s SBS
0846+513, PKS 1502+036, and PKS 2004-447 detected by Fermi-LAT. The
information on the pc-scale morphology will be complemented with
studies of flux density and spectral variability from multi-epoch and
multifrequency observations, in order to unveil the nature of their

------------------------------------------------------------------------
Name: Alexander Pushkarev

Title: Apparent parsec-scale jet opening angles and gamma-ray
brightness of blazars

Authors: A.B. Pushkarev (Pulkovo Observatory; Crimean Astrophysical
Observatory)
M.L. Lister (Purdue University)
Y.Y. Kovalev (Astro Space Center of Lebedev Physical Institute; Max-Planck-Institut fuer Radioastronomie)

Abstract: We have investigated the differences in apparent opening
angles between the parsec-scale jets of the AGN detected by the Fermi
Large Area Telescope during its first 24 months of operations and
those of non-LAT-detected AGN. We used 15.4 GHz VLBA observations
of 215 sources from the 2 cm VLBA MOJAVE program. The apparent opening
angles were determined by analyzing transverse jet profiles from the
data in the image plane by using stacking images consturcted from all
vailable MOJAVE epochs for a given source. We confirm our earlier
result based on the first three months of scientific operations of
the LAT. The apparent opening angles of gamma-ray bright blazars are
preferentially larger than those of gamma-ray weak sources, suggesting
smaller viewing angles. Additionally, intrincsic opening angles are
derived and discussed.

------------------------------------------------------------------------
Name: Soebur Razzaque

Title: Lower limits on ultrahigh-energy cosmic ray and jet powers of
TeV blazars

Authors: Soebur Razzaque, Charles D. Dermer and Justin D. Finke

Abstract: Lower limits on the power emitted in ultrahigh-energy cosmic
ray (UHECR) protons are derived for TeV blazars with the assumption
that the observed TeV gamma rays are generated due to interactions of
these protons with cosmic microwave photons.  This mechanism may be at
work in four blazars, namely 1ES 0229+200; 1ES 1101-232; 1ES 0347-121
and 1ES 1426+428, which are at sufficiently high redshift (>0.1) that
allow efficient cascade development to make TeV emission and which are
non-varying or very weakly varying at >TeV energies. The lower limits
on the UHECR power are lower than the respective synchrotron
luminosities in case of all blazars except for 1ES 1426+428. The
proposed Auger North Observatory can detect 40 EeV cosmic rays from
this extraordinary source and test the UHECR-generated TeV emission
model, which requires the intergalactic magnetic field strength to be
below 10^-16 G. The lower limits on the jet power for all four TeV
blazars exceed the Eddington luminosity of a 10^9 solar mass black
hole in case the injected UHECR spectrum is softer than E^-2.2.

------------------------------------------------------------------------
Name: Jamie Stevens

Title: ATCA Monitoring of gamma-ray loud AGN

Authors: Jamie Stevens (CSIRO), Phil G. Edwards (CSIRO), Roopesh Ojha
(NASA/GSFC), Matthias Kadler (Univ. Wurzburg), Faith Hungwe (Rhodes
Univ./HartRAO), Michael Dutka (Catholic Univ.)

Abstract: We present selected data from four years of periodic
monitoring of 130 sources detected by the EGRET and Fermi-LAT
telescopes using the Australia Telescope Compact Array (ATCA). The
ATCA observations described here cover the frequency range 4.5 - 41
GHz, which allows for the spectral index time variability to be
examined. In this poster we give some examples of sources that have
varying spectral indices, as well as some that do not show such
behaviour. We also discuss the science possible with our data.
------------------------------------------------------------------------

Name: David J. Thompson

Title: Flaring Activity from S5 0836+71 (4C71.07) What Can We Learn
with Limited Multiwavelength Coverage?

Authors: D. J. Thompson, D. Donato (NASA/GSFC), A. Akyuz (Univ. of
Cukorova), L. Fuhrmann, K. Sokolovsky (MPI for Radioastronomy), on
behalf of the Fermi LAT Collaboration, O. Kurtanidze (Abastumani
Observatory)

Abstract: After a long period of quiescence in gamma rays, blazar S5
0836+71 (4C71.07), redshift z = 2.218, flared in the Spring of
2011. We found only limited multiwavelength coverage of the source. An
indication of correlated optical/gamma-ray variability is not
surprising for a FSRQ like this one. Radio observations at high
frequencies, however, had seen a flare in late 2010, with no apparent
related gamma-ray activity. This case may differ from the traditional
pattern of finding gamma-ray flares during times of rising radio
emission.

------------------------------------------------------------------------
Name: Gino Tosti

Title: Observation of blazars with the high energy SED peak in the
Fermi-LAT band

Authors: Gino Tosti (Universit di Perugia/SLAC)
Claudia Monte (INFN Bari)
Luigi Costamante (no affiliation)
Stefano Ciprini (INAF/ASI)
Silvia Rain (INFN/Bari)

Abstract: Among the AGN included both in the 1LAC and in the 2LAC, a
particular and interesting group of objects is the one composed by
those blazars that have their Spectral Energy Distribution (SED)
high-energy peak centered on the Fermi-LAT band (from 20 MeV to 300
GeV). The brightest of these sources have been selected and they have
been analyzed covering a period of 22 months of Fermi LAT gamma-ray
data in order to investigate their spectral features in the gamma-ray
band and to characterize the temporal evolution of their gamma-ray
spectra.

------------------------------------------------------------------------
Name: Stefano Vercellone

Title: The gamma-ray flaring properties of the blazar 3C 454.3

Authors: Stefano Vercellone (INAF/IASF Palermo) on behalf of the AGILE Team

Abstract: 3C 454.3 is the most variable and intense extragalactic
gamma-ray blazar detected by AGILE and Fermi during the last 4
years. This remarkable source shows extreme flux variability (about a
factor of 20) on a time-scale of 24-48 hours, as well as repeated
flares on a time-scale of more than a year. The dynamic range, from
the quiescence up to the most intense gamma-ray super-flare, is of
about two orders of magnitude. We present the gamma-ray properties of
3C 454.3 by means of the available data, comparing both the
characteristics of flares at different levels and their
multi-wavelength behaviors. Moreover, an interpretation of both the
long- and short-term properties of 3C 454.3 is reviewed, with
particular emphasis on the two gamma-ray super-flares observed in 2009
and 2010, when 3C 454.3 became the brightest source of the whole
gamma-ray sky.
`

### Contact

Roopesh Ojha, roopesh.ojha@gmail.com