On behalf of the Radio-Agile AGN WG Blazar radio properties and monitoring Tiziana Venturi tventuri@ira.inaf.it On behalf of the Radio-Agile AGN WG 7th Agile Workshop & The Bright Gamma-ray sky Rome 29.09.09

Outline of the presentation Radio and γ-ray loud AGN The radio jets and observable quantities Multiband campaigns and radio/γ-ray studies before the advent of AGILE and FERMI Current monitoring programs Radio-AGILE AGN WG – 3C454.3 Overview of future radio facilites

Universal Blazar SED Steep FSRQ Log Luminosity νLν(erg/s) radio mm Flat BL Lacs Adapted from Fossati 2009 A correlation is expected between the variability at low and high energy: γ-ray flare -> radio flare The few multiband campaigns carried out so far from the mid-90’s are not conclusive

Radio power vs γ ray luminosity FSRQ BL Lacs Adapted from Fossati 2009

Courtesy of A. Marscher From the radio point of view, γ-ray loud AGN are Flat Spectrum Radio Quasars and BL Lac objects, i.e. radio sources whose radio emission is aligned at a small angle to the observer’s line of sight. The “radio core” is actually the base of the jet, and its location depends on the observing frequency. Parsec-scale radio imaging allows a direct look into the inner jets of blazars.

3C279 VLBA 43GHz The favourable viewing angle and the high intrinsic speed of the radio emitting plasma, lead to strong flux density and structural variability, and superluminal proper motion

Distribution of superluminal proper motion in quasars and BL Lacs from VLBA 43 and/or 22 GHz multiepoch maging Jorstad et al. 2001

From the radio point of view, the underlying idea is that a γ-ray flare may be related to a radio flare, and that new superluminal components may be ejected during the radio flare Multiband observations of γ-ray loud blazars and multiepoch radio imaging are necessary to test this

Before the advent of AGILE & FERMI 1) Only a handful of simultaneous multiband campaign carried out on the best known blazars (i.e. 3C279, Mrk 421 …) with a variety of results (Hartmann et al. 2001; Blazejowski et al. 2005).

2) A-posteriori search for correlation between radio and γ-ray flares and superluminal ejections (UMRAO monitoring and EGRET sources, Jorstad et al. 2001) γ-ray radio γ-ray flare Superluminal ejection

Current radio programs - I. Imaging Monitoring Radio/γ-ray studies of AGN in the AGILE and FERMI era Current radio programs - I. Imaging Monitoring MOJAVE Imaging + monitoring survey (~200 sources) – VLBA @15 GHz TANAMI southern monitoring of blazars (~80 sources) – LBA @ 8.4 & 22 GHz BU Blazar Group 22 & 43 GHz VLBA imaging monitoring of ~ 20 sources VIPS VLBI Imaging and Polarimetry Survey, VLBA@5 GHz, ~1200 sources USNO-RRFID Database of geodetic observations at 2.3/8.4 GHz and 22 GHz DXRBS EVN observations at 5 GHz of ~ 100 sources from the DXRBS sample

Current radio programs - II. Single dish monitoring UMRAO UMich Radio Observatory, full polarization long term monitoring at 4.8, 8.4, 15 GHz of ~ 50 bright sources Ratan monitoring survey of ~ 700 bright sources Metsahovi long term monitoring (~ 100 sources) @ 22 & 37 GHz OVRO daily monitoring of ~ 1000 sources @ 15 GHz FGamma Eb (11cm to mm)/IRAM (1,2,3 mm) simultaneous monitoring Medicina and Noto Monthly monitoring of ~ 30 sources at 5, 8.4 and 22 GHz

Radio-AGILE AGN Working Group Multiepoch parsec-scale imaging of AGILE bursting AGNs Instruments VLBA Frequencies 22 GHz and 43 GHz Number of epochs 10 On trigger proposal Active until the end of 2009 Goals Accurate morphological classification Evolution of polarimetric properties close to the γ-ray flare Morphological changes

Strategy First 4 epochs as soon as the gamma ray burst is announced and separated by one week each this observation would provide the “zero image” and the evolution of the polarisation properties close to the flare Subsequent 6 epochs once/month The time spacing of the epochs allows us to sample a broad range of apparent proper motions, hence of beaming Comment: source list had to be revised since the first proposal submission, as the brightest γ ray loud blazars are all in the BU Monitoring Program (Marscher)

The sample

AGILE campaign in the period May 2008 – January 2009 + RXTE (3-20 keV) The case of 3C454.3 Vercellone et al. 2009 AGILE campaign in the period May 2008 – January 2009 + RXTE (3-20 keV) Swift GASP/WEBT UMRAO + MOJAVE radio data

3C454.3 in the radio band z = 0.859 strong quasar with superluminal motion 7.70 pc/mas along the one-sided jet Dl 5489 Mpc 43 GHz @ VLBA βapp (B6) ~ 13.3 – 18.8c Jorstad et al. 2005

Multifrequency light curves The radio flux density is steadily increasing, and not in the form of flares. The radio peak is reached at a time when the γ-ray emission is not flaring

Images from the MOJAVE monitoring in 2007 - 2008 15 GHz - 7 Aug 2007 Total flux density increase due to the radio core (component C) Flux density of the main jet components stable or decreasing No proper motion along the jet No birth of new components so far From the core variability at 43 GHz it was derived that the source is viewed at θ~1.5° and that Γ~20

Main current and future VLBI facilities In order to look into the inner jets, parsec-scale imaging (mas & sub-mas resolution) is needed Very Long Baseline interferometry & high radio frequencies (i.e. above 5 – 8.4 GHz) Main current and future VLBI facilities Ground VLBA (δ≥ -30o) : up to 43 GHz, 512 Mbps www.nrao.edu GMVA (δ≥ -30o ): up to 86 GHz LBA (southern hemisphere): up to 22 GHz European VLBI Network (δ ≥ -10o): up to 22 GHz, 1 Gbps www.evlbi.org e-EVN, more flexible and more frequent than EVN

Space VLBI in the near future ASTRO-G – 2012 www.vsop.iasa.ac.jp/vsop2 Dual Pol. – 8.4, 22, 43 GHz Space Radio Telescope – 2010 327 MHz, 1.6, 4.8, 15-22 GHz www.asc.rssi.ru/radioastron/news/news.html sub-mas to μas resolutions from 327 MHz to 43 GHz