Exploring the FRI/FRII radio dichotomy with the Fermi satellite Fermi and Jansky: Our Evolving Understanding of AGN PAOLA GRANDI INAF/IASF BOLOGNA, ITALY Fermi-LAT Collaboration E. Torresi (IASF, Italy) November 10-12, 2011 Harbour towne Conference Center St Michaels, MD, USA Friday, November 11, 2011
BL LACs FSRQs The Fermi sky Other Extragalactic Sources 90 1 year 60 The clean sample of the First Catalog of AGN (1LAC) contains 599 sources 30 180 150 120 90 60 30 0 -30 -60 -90 -120 -150 -180 Abdo, A. A., et al. 2010a, ApJ, 715, 429 (1LAC); Abdo, A. A., et al. 2010b, ApJS, 188, 405 (1FGL) -30 -60 -90 2 years In the Second Catalog of AGN (2LAC-ApJ in press) , the number of detected AGNs is increased by more than 40% (877 sources). Friday, November 11, 2011
The majority of Extragalactic Sources are BL LAC and FSRQs δ =1/ Γ (1- β cos θ ) The Doppler factor relates intrinsic and observed flux for a moving source at relativistic speed v = c . For an intrinsic power law spectrum: Blazar F’( ’) = K (v’) -a the observed flux density is Γ F ( )= p F’ ’ ( ) p=n+ Friday, November 11, 2011
However ~3% of the -sources are not Blazars The “other” Extragalactic Sources belongs to two broad classes of objects reflecting two different particles acceleration processes: 1. ¡ SNR as particle accelerator -- SNR expanding shocks -> CR acceleration -> - rays Starburst Galaxies h9p://wwwmagic.mppmu.mpg.de/magic/index.html 2. ¡AGN ¡as ¡par0cle ¡accelerator ¡ ¡-‑> ¡Jets Narrow Line Seyfert 1 Sources Misaligned AGNs ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ 4 Friday, November 11, 2011
After 24 months of sky survey Non-Blazars Blazars Friday, November 11, 2011
2. ¡AGN ¡as ¡par0cle ¡accelerator: ¡Misaligned ¡AGN ¡(MAGN) With MAGNs we intend Radio Sources with the jet not directly pointed towards the observer. MAGNs Γ NLRG MAGNs BLRG ¡ ¡ ¡ SSRQs BL ¡LACs Blazars FSRQS 6 Friday, November 11, 2011
MAGNs show: Steep Radio Spectra Resolved and possibly symmetrical > 0.5 and/or structures in radio map FRI are considered the PARENT POPULATION of BL LACs FRII are considered the PARENT POPULATION of FSRQs (SSRQs are in between) However the picture could be more complex (see Kharb, Lister and Cooper ApJ 2010) 7 Friday, November 11, 2011
FIRST SAMPLE of MAGNS (15 MONTH-DATA) Abdo, A. A., et al. 2010, ApJ, 720, 912 (MAGN) MAGNs are generally faint and soft sources F(>0.1 GeV)~10 -8 Phot. cm -1 s -2 2.4 FRII SSRQ FR I Radio Galaxy Friday, November 11, 2011
The association of MAGNs to -ray LAT sources has raised some questions: First question T ext Are we really missing FRII radio galaxies? Friday, November 11, 2011
2 Jy sample =2.7 GHz 3CRR sample =178 MHz 3CR sample =178 MHz Molonglo Southern 4Jy sample MS4 =408 MHz F> 2 Jy F> 10.9 Jy F> 9 Jy F> 4 Jy 88 sources 173 sources 113 sources 228 sources Number of sources Radio Sources of 3CRR+3CR+2Jy+MS4 catalogs Radio Sources of 3CRR+3CR+2Jy+MS4 catalogs with LAT association Friday, November 11, 2011
Rate of Detections for each class Source with TS >25 15 and 24 months of sky survey Percentage of radio sources with -ray emission FRII are the less detected objects The -ray elusiveness of FRIIs has been also confirmed by a dedicated study of Broad Line Radio Galaxies (Kataoka et al. 2011) Friday, November 11, 2011
Are FRIIs elusive GeV sources because too far? Maybe not! Log (f ) 1 GeV = a + b x Log(f ) 5 GHz a b r P_r 5.1 0.7 TOT 0.74 >99.9% (1.0) (0.1) TOT 6.2 0.6 0.65 99.9% (1.6) (0.2) TS>25 MAGN 7.9 0.4 0.66 97.4% (1.2) (0.1) TS>25 The Radio ray fluxes are correlated see also: Ghilranda et al. 2011, Ackermann et al. 2011 ApJ in press Friday, November 11, 2011
Predicted fluxes @ 1 GeV of the 3CR+3CRR+MS4+2Jy sources Log (f ) 1 GeV = a + b x Log(f ) 5 GHz Predicted Observed correlation based on the MAGN sample FRII: expected sources FRII: observed sources FRI: expected sources FRI: observed sources Friday, November 11, 2011
Predicted fluxes @ 1 GeV of the 3CR+3CRR+MS4+2Jy sources Log (f ) 1 GeV = a + b x Log(f ) 5 GHz Predicted Observed correlation based on the total sample FRII: expected sources FRII: observed sources FRI: expected sources FRI: observed sources A large number of FRIIs should cross over the LAT sensitivity threshold. In spite of this, only a handful of FRIIs is seen at GeV energies ( see also Dermer & Benoit 2011) 14 Friday, November 11, 2011
Radio Flux indicates that the “core” of FRIIs is bright enough to be visible at very high energies Second question Why does Fermi-LAT preferentially catch FRIs and lose FRIIs ? Friday, November 11, 2011
SED studies of FRI Radio galaxies indicate that a pure, one-zone homogeneous, synchrotron self-Compton model is problematic Slow SSC jets are also required in other MAGNs NGC6251: an example (Migliori et al. 2011) (M87:Abdo et al. 2009; NGC1275: Abdo et al. 2009) Model Parameters: =25° =2.4 R~10 17 cm B~0.04 G N=K -p p 1 =2.76 p 2 =4.04 K~2 × 10 6 cm -3 break =2 × 10 4 min =250 max =2 × 10 5 The one-zone homogeneous SSC model applied to MAGNs needs too slow jets BL > MAGN Possible conflict with Unified Models Friday, November 11, 2011
Possible solutions to the problems (not the only ones) v Decelerating jet (Georganopoulos & Kazanas 2003) v Structured (spine +slower layers) jet (Ghisellini, Tavecchio & Chiaberge 2005) v Colliding shells (Bottcher & Dermer 2010) T h e h y p o t h e s i s o f homogeneity is relaxed and more regions at different velocities are assumed. These models can generally fit pretty well the SEDs of The jet is structured FRI radio galaxies. 17 Friday, November 11, 2011
Possible solutions to the problems (not the only ones) v Decelerating jet (Georganopoulos & Kazanas 2003) v Structured (spine +slower layers) jet (Ghisellini, Tavecchio & Chiaberge 2005) v Colliding shells (Bottcher & Dermer 2010) T h e h y p o t h e s i s o f Γ 2 Γ 1 homogeneity is relaxed and more regions at different velocities are assumed. These models can generally The jet is decelerated fit pretty well the SEDs of FRI radio galaxies. 18 Friday, November 11, 2011
Possible solutions to the problems (not the only ones) Possible solutions to the problems (not the only ones) v Decelerating jet (Georganopoulos & Kazanas 2003) v Decelerating jet (Georganopoulos & Kazanas 2003) v Structured (spine +slower layers) jet (Ghisellini, Tavecchio & Chiaberge 2005) v Structured (spine +slower layers) jet (Ghisellini, Tavecchio & Chiaberge 2005) v Colliding shells (Bo”ttcher & Dermer 2010) v Colliding shells (Bottcher & Dermer 2010) T h e h y p o t h e s i s o f T h e h y p o t h e s i s o f Colliding shells homogeneity is relaxed and homogeneity is relaxed and Γ 2 Γ 1 more regions at different more regions at different velocities are assumed. velocities are assumed. The jet is decelerated The jet is structurated These models can generally These models can generally fit pretty well the SEDs of fit pretty well the SEDs of The jet is shocked FRI radio galaxies. FRI radio galaxies. 19 Friday, November 11, 2011
(Migliori et al. 2011) IC Layer Structured Jet =25° SSC Layer Layer =2.4 Spine =15 SSC Spine In the spine-layer and decelerating models there is an efficient (radiative) feedback between different regions in the jet that increases the IC emission. Models can fit the Spectral Energy Distributions of FRIs. Friday, November 11, 2011
The jet of FRIIs could be less structured (spine dominated) or/and less decelerated 21 Friday, November 11, 2011
and/or =15 In FRII the jet propagates through a photon rich environment (see Torresi’s talk) => EC dominant mechanism . EC emission is narrower in the beaming direction than the SSC radiation (Dermer 1995, ApJ, 446, L63) EC SSC Friday, November 11, 2011
Third question T ext Where do the -rays originate in radio galaxies ? Friday, November 11, 2011
Where are the -ray produced in Radio Galaxies? in/near the radio core (sub-pc/pc scales)? in large extended regions (kpc-scale structures) Cen A Lobes Abdo et al. 2010, Science, 328, 725 NGC1275 Abdo et al. 2010 (MAGN) Brown&Adams 2011 Friday, November 11, 2011
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