F-GAMMA: multi-frequency radio monitoring of Fermi blazars E. - PowerPoint PPT Presentation

F-GAMMA: multi-frequency radio monitoring of Fermi blazars E. Angelakis, I. Myserlis, & J. A. Zensus Max-Planck-Institut für Radioastronomie, Auf dem Huegel 69, Bonn 53121, Germany on behalf of the F-GAMMA team

the F-GAMMA program (Jan 2007 — Jan 2015): ➡ almost 90 mostly Fermi sources ➡ localise the gamma-ray emission site ➡ 2.64 - 142, 229, 345 GHz at 12 frequency steps ➡ understand the broad-band variability ➡ mean cadence 1.3 months ➡ estimate the properties of the emitting elements Fuhrmann, Angelakis et al., 2016, A&A, 596, A45

gamma-ray emission site

γ rays gamma rays production site? Relativistic jet Broad Line Region (BLR) γ -ray emission region <~ 1 pc Accretion disk ~ 1 – 10 pc Dust torus γ -ray emission region Relativistic jet Broad Line Region (BLR) <~ 1 pc Accretion disk ~ 1 – 10 pc Dust torus Karamanavis et al A&A 590, A48 (2016) Fuhrmann et al MNRAS 441, 1899 (2014)

the exercise: ➡ ~ 3.5-year light curves of 54 Fermi blazars ➡ search for radio/ γ -ray correlations relative timing of flares results: ➡ 9 cases significant ➡ radio bands delay with respect to gamma rays significant correlation interpretation: ➡ Delay origin: opacity synchrotron self-absorption (SSA) dominated: - γ rays escape immediately while radio progressively later no significant correlation Fuhrmann et al MNRAS 441, 1899

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physical processes at the emission elements

the Radiopol since 2015 … ➡ almost 18 Fermi sources ➡ 2.64 - 43 GHz ➡ LP at 2.64, 4.85, 8.35, 10.45 and 14.6 GHz ➡ CP at 2.64, 4.85, 8.35, 10.45, 14.6, 23.05 GHz ➡ mean cadence 2 weeks Myserlis, Angelakis et al. 2016Galax…4…58M Angelakis, Myserlis & Zensus, Galaxies, doi: 10.20944/preprints201708.0108.v1

the Radiopol since 2015 … ➡ almost 18 Fermi sources ➡ 2.64 - 43 GHz ➡ LP at 2.64, 4.85, 8.35, 10.45 and 14.6 GHz ➡ CP at 2.64 , 4.85, 8.35, 10.45, 14.6, 23.05 GHz ➡ mean cadence 2 weeks Myserlis, Angelakis et al. 2016Galax…4…58M Angelakis, Myserlis & Zensus, Galaxies, doi: 10.20944/preprints201708.0108.v1

the Radiopol since 2015 … ➡ Uncertainties: - LP degree: 0.1 % - CP degree: 0.1—0.2 % - EVPA: 1° ➡ near future: 90 srcs, 5 LP and 6 CP over at least 8 + 2 +… years Myserlis, Angelakis et al. 2016Galax…4...58M Myserlis et al. 2017, A&A, arXiv: 170604200M

3C279 3C454.3 2006.7 2014.9 2006.7 2014.9 the picture: variability caused by episodic activity that undergo spectral evolution. We assume: ➡ magnetised jet with partially uniform magnetic field, ➡ occasional traveling disturbances, ➡ particles at the shocked areas radiate flaring emission which undergoes spectral evolution Angelakis, Myserlis & Zensus, 2017Galax…5...81A Myserlis et al. in prep.

Slab jet shape B Cell B = B 0 (r/r 0 ) -q Line of sight n( γ )d( γ ) = n 0 γ -s d γ , γ > γ i Myserlis, Angelakis et al. 2016Galax...4...58M, ν based on Hughes et al. (1989)

jet shape k compression factor Cell Density Line of sight 0 = n 0 k � s +3 n 0 6 Lower energy cutoff min = E min k � 1 E 0 3 B-field strength B 0 ∼ kB ν

the high- γ min regime: ➡ each cell has a 100% uniform B-field parallel to the jet with 5% of the amplitude of the local field ➡ B 0 ~ 5 mG Shock parameters: ➡ Compression factor: k = 0.8 (mild shock) 4 ➡ γ min ~ 10 ➡ Doppler factor: D ~ 30 
 Consistent with D var at 37 GHz 
 Hovatta et al. (2009) Jet plasma parameters (un-shocked jet) -3 ➡ Density: n 0 = 10 - 100 cm ➡ Magnetic field coherence length: 9 pc Angelakis, Myserlis & Zensus, 2017Galax...5...81A Myserlis et al., Galaxies, vol. 4, issue 4, p. 58 Myserlis, Angelakis et al.,in prep.

Observed lightcurves Synthetic lightcurves 8.35 GHz 8.35 GHz I (Jy) LP (%) χ (°) CP (%) MJD Myserlis, Angelakis et al.,in prep. Myserlis et al., Galaxies, vol. 4, issue 4, p. 58

the low- γ min regime: NGC 4845 Irwin et al, 2015,ApJ…809..172I ➡ evolving convex radio spectrum with a peak around 3-5 GHz ➡ LP: practically zero (0.1–0.5 %) at both 1.5and 5 GHz ✘ ➡ CP: - unusually high at 1.5 GHz: 2–3 % ✔ - zero at 5 GHz ✔ we examined whether the high CP is caused by converting linear to circular polarisation 
 Realisation ➡ conical adiabatically expanding outflow ➡ random B-field ➡ γ min ∼ 10–100 
 We find: ➡ there is transformation of LP to CP at 1.5 GHz Faraday conversion, hence: - the low LP and high CP degrees 
 ➡ Low LP at 5 GHz cannot be reproduced with 
 this realisation. - an excess of low-energy magnetised plasma within or around the flow may be causing de-polarisation through Faraday rotation. 
 line of sight 17

To summarise : ➡ vast dataset: 281 observing sessions , more than 40 proposals , more than 40 papers - cross correlation with gamma rays: location of the gamma-ray emission - internal shocks as the variability mechanism - mildly relativistic/powerful radio jet in Narrow Lines Seyfert 1 galaxies similar to bazars - Scale Invariant Jets: From Blazars to Microquasars - … etc

To summarise : ➡ polarisation: 90 srcs, 5 LP and 6 CP over at least 8 + 2 +… years - 11300 data points with Full-Stokes (I, Q, U, V) ➡ Toy model: shock-driven variability and evolution works well both at: - high γ min regime - low γ min regime - and the reproduction of physical processes

Thank you! Emmanouil Angelakis, Ioannis Myserlis & J. Anton Zensus Max-Planck-Institut für Radioastronomie, Auf dem Huegel 69, Bonn 53121, Germany