The Extragalactic Gamma-Ray View of AGILE and Fermi

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1 INAF, Osservatorio Astronomico di Capodimonte 22 February 2012 The Extragalactic Gamma-Ray View of AGILE and Fermi Elena Pian INAF, Trieste Astronomical Observatory & Scuola Normale Superiore di Pisa

2 UNIFIED SCHEME OF AGN (Urry & Padovani 1995) 10% of all AGNs are radio-loud, and a small fraction of these are blazars

3 Extragalactic Jets: radiogalaxies and blazars Lorentz factors Γ~ Cen A d = 4 Mpc Virgo A (M87) d = 20 Mpc VLA z = 0.056

4 UNIFIED SCHEME: Blazars are radiogalaxies with their jets pointing at a small angle with respect to the observer line of sight: 1) Superluminal motions 2) Radio spectra are not self-absorbed despite the small emitting region 3) Gamma-rays at MeV and higher energies are observed!

5 VLBI monitoring of radio structures and blobs ~5c Radio-blobs emitted at different epochs may have different apparent velocities, vapp = βappc 43 GHz; Jorstad et al ~20c " = " app " app cos# + sen# BL Lac GHz; Mutel et al. 1990

6 VLBA observations at 7 mm (43 GHz) of BL Lac 5c Marscher et al Lorentz factor: " = 1 1# $ 2 " = 1 Doppler factor: #(1$ %cos&) If we assume that θ = 5 deg: βapp = 5 β = Γ = 6 δ = 9.5 βapp = 20 β = Γ = 30 δ = 7.6

7 Brightness Temperature argument T B = c 2 F " 2k" 2 # 2 For observed radio fluxes and angular sizes (directy measured with VLBI or inferred from radio variability), TB ~ e11 K The GHz spectra of blazars are flat (α < 0.7, where F ~ ν^-α), but not self-absorbed " 2.5 Torniainen et al. 2007

8 Compactness Argument Compactness: l = L" T Rm e c 3 Optical depth for photon-photon collision: " ## $ l 60 x% x x = h" mc 2 For an energy of 5 GeV (x = 10000), luminosity L = e48 erg/s, size of the emitting region R = 2 light days, and X-ray spectral slope α = 0.5, τ is about 100, therefore no gamma-rays should escape Solution of the paradox: L int r = " #3 L obs R int r = ct var 1+ z " $ int r = $ obs " By imposing that τ < 1, one has δ 6 McBreen 1979; Maraschi et al. 1992

9 The Fermi GST mission: 11 June 2008 LAT, GeV Glast Burst Monitor Energy Range: 10 kev - 30 MeV 12 Sodium Iodide (NaI) Scintillation detectors Burst trigger Coverage of the typical GRB spectrum (10 kev 1 MeV) 2 Bismuth Germanate (BGO) Scintillation detectors Spectral overlap with the LAT (150 kev-30 MeV) Courtesy: N. Omodei

10 Second Fermi LAT Catalog (2FGL): 1873 sources (576; 187 of these already identified as blazars thru comparison with WISE Catalog, Massaro et al. 2012) (~1000, compare with 66 CGRO-EGRET blazars!)

11 Blazars in the Fermi-LAT sky (FSRQ) (FSRQ) (FSRQ) (BL Lac)

12 First Fermi-LAT observation of the FSRQ 3C454.3 (z = 0.859) 2008 Jul 7 - Aug 2 Abdo et al. 2009

13 AGILE-GRID observation of the FSRQ 3C454.3 (z = 0.859): Jun 2007 (30 MeV - 50 GeV) 2008 Jul 7 - Aug 2 Vercellone et al. 2008

14 3C454.3 E-06 ph/s/cm2 AGILE-GRID and MWL observations of 3C454.3, November 2010: the very high gamma-ray state can be reproduced by external Compton scattering off variable seed photons mjy INTEGRAL Jy Leptonic model of synchrotron Plus SSC and external Compton Vercellone et al. 2011

15 Fermi-LAT discovery of FSRQ PKS (z = 1.839) Variable parameters: accelerating power of electrons and Magnetic field Aug 2008 INTEGRAL Position circles Seyfert 1 galaxy 1 The blazar target was not detected by INTEGRAL, but we detected serendipitously a Seyfert 1! Corona and Accretion disk Pian et al. 2011

16 Simultaneous AGILE and VERITAS observations of the BL Lac object Mkn421 (z = 0.031), 2008 May 24 - Jun 23 Donnarumma et al. 2009

17 Fermi-LAT and MWL campaign of Mkn421 (2009 Jan 19 - Jun 1) Abdo et al. 2011

18 Spectral energy distribution of blazars and spectral sequence

19 Is the blazar sequence an exhaustive representation? z > 1.2 Padovani & Giommi 2012

20 Spectral Energy Distribution of Flat Spectrum Radio Quasars HBL: High synchrotron peak frequency Accretion disk Ghisellini et al. 2011

21 Fundamental properties of gamma-ray Blazars accretion must play a key role in producing the jet Ghisellini et al. 2011

22 Optical polarimetry of FSRQ PKS (z = 0.36) in January - June 2009, during an outburst Marscher et al. 2010

23 X-ray polarimetry to study geometry of jets S (Z = 0.342) Sambruna et al GEMS, to be launched in 2014 Gas Pixel Detector (PI: Enrico Costa) Both based on photoelectric effect

24 NuSTAR: Nuclear Spectroscopic Telescope Array The NuSTAR mission will deploy the first focusing telescopes to image the sky in the high energy X-rays (6-79 kev)

25 Summary Blazars extreme luminosities and variability at all wavelengths depend on the kinematic conditions and orientation of their powerful jets Blazars constitute the majority of the detected MeV-GeV extragalactic persistent emitters Blazar spectra are predominantly non-thermal (syncrotron and Inverse Compton), but their accretion disks are occasionally observed, especially in FSRQs, and allow the measurement of the central BH mass The accretion on this black hole plays a fundamental role in producing the jet power

26 Swift J = a relativistic jet from a tidal disruption flare (GRB110328A) Swif BAT, XRT z = kev kev Chandra 1 WSRT MBH = 1-20 e6 M masses (based on X-ray variability time-scale and MBH vs Mbulge Relationship) super-eddington accretion regime beaming along observing direction Levan et al. 2011; Zauderer et al. 2011; Burrows et al. 2011; Bloom et al. 2011