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Charles D. Dermer Space Science Division US Naval Research Laboratory, Washington, DC

Fermi AGNs: the L AT B right A GN S ample (LBAS) from the First Three Months of the Fermi Large Area Telescope All-Sky Survey. Charles D. Dermer Space Science Division US Naval Research Laboratory, Washington, DC charles.dermer@nrl.navy.mil February 18, 2009

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Charles D. Dermer Space Science Division US Naval Research Laboratory, Washington, DC

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  1. Fermi AGNs: the LAT Bright AGN Sample (LBAS)from the First Three Months of the Fermi Large Area Telescope All-Sky Survey Charles D. Dermer Space Science Division US Naval Research Laboratory, Washington, DC charles.dermer@nrl.navy.mil February 18, 2009 Goddard Space Flight Center

  2. Fermi Bright Sources • Subset of LAT Bright Source List, 0FGL (Fermi Gamma ray LAT): Abdo et al. arXiv:0902.1340 • LBAS: Abdo et al. arXiv:0902.1559 • 0FGL: 205 LAT Bright Sources • Test Statistic > 100 • Significance > 10s • Not complete • Not flux-limited • Not uniform • 132 |b|>10 sources • 114 associated with AGNs August 4 – October 30, 2008

  3. EGRET Legacy 66 hi-confidence (>5s) sources associated with AGNs (Hartman et al. 1999) 31 >10s sources (total) (10 at |b|>10) All associated with radio-loud AGNs—blazars + 1 radio galaxy 23% with BL Lac objects 77% with flat spectrum radio quasars zmax = 2.286 Blazars: OVV quasars flat radio spectrum (ar>-0.5 at GHz frequencies) superluminal motion

  4. Radio Galaxies and Blazars Cygnus A 3C 279 FR2/FSRQ Mrk 421, z = 0.031 • spectra • unification • evolution L ~1045 x (f/10-10 ergs cm-2 s-1) ergs s-1 FR1/BL Lac 3C 279, z = 0.538 3C 296 W Comae L ~5x1048 x (f/10-9 ergs cm-2 s-1) ergs s-1

  5. Bright Source Sample • Diffuse class (E > 100 MeV); pointfit, gtlike maximum likelihood algorithm • Weekly peak flux and average flux over 3 month interval • Power-law spectral form kE-G 10s Flux limit as a function of sky location, assuming G = 2.2 Compare 5s two-week limit for EGRET  150x10-9 -- 250x10-9

  6. Associations (not Identifications) • Depends primarily on spatial coincidence • Catalogs used: • CRATES: Combined Radio all-Sky Targeted Eight GHz Survey • 11,000 |b|>10 flat-spectrum with positions, 8.4 GHz flux densities, ar • CGRaBS: Gandidate Gamma-Ray Blazar Survey • 1625 CRATES sources with similar radio and X-ray properties as EGRET blazars • BZCAT • Radio/optical list of 2700 blazars/blazar-like sources: BL Lac, FSRQ, uncertain

  7. LAT Bright AGN Sources • 103 in BZCat (E. Massaro et al.), spatial coincidence • Figure of Merit method (Healey, Romani) • 77 in CGRaBs, 106 in CGRaBs+CRATES • 114 of 132 sources associated with |b|>10 AGNs • 7 pulsars, 11 unidentified, 4 new blazars • 2 radiogalaxies: Cen A, Perseus 3C 84/NGC1275 Error radius vs. TS (cf. EGRET with ~0.6)

  8. Blazars in the LBAS • FSRQs: 57, BL Lacs: 42, Uncertain: 5 • >40% BL Lacs (23% in 3EG), 10 HBLs (11 TeV sources, inc. 7 HBLs, 3 LBLs, and 3C279) • 33/111 (30% AGNs) in 3EG catalog • FSRQs: 19, BLLacs: 11, Uncertain: 3

  9. Properties of LBAS • 106 high-confidence associations • 10 low-confidence associations • 116 AGNs in Table 3: • Name • Location • TS • G • F100 • Weekly peak flux • F25 • Variability index

  10. Photon Index vs. Flux

  11. Spectral Index Distribution • Sampling separate FSRQ and BL Lac populations

  12. Flux Comparison with EGRET Fermi: 0.25 yr × 2.4 sr = 0.6 sr-yr vs. EGRET: 4.5 yr × 0.5 sr = 2.2 sr-yr

  13. Redshift Distribution • Similar to EGRET distributions

  14. Log N – Log S and Extragalactic g-Ray Intensity Total BL Lacs FSRQs

  15. V/Vmax

  16. Log N – Log S and Extragalactic g-Ray Intensity Total BL Lacs FSRQs

  17. Unresolved g-Ray Background BL Lacs: ~2 - 4% (at 1 GeV) FSRQs: ~ 10 - 15% Star-forming galaxies (Pavlidou & Fields 2002)Starburst galaxies(Thompson et al. 2006) Pulsar contribution near 1 GeV Galaxy cluster shocks (Keshet et al. 2003, Blasi Gabici & Brunetti 2007) Dark matter contribution (talk by Bergstrom) astro-ph/0610195 Data: Sreekumar et al. (1998) Strong, Moskalenko, & Reimer (2000)

  18. Luminosity vs. Redshift • Solid line refers to a flux limit of 4x10-8 ph(>100 MeV) cm-2 s-1 and G = 2.2

  19. Radio/g ray Correlations • Radio/g-ray correlation important in population studies Peak g-ray flux vs. 8.4 GHz radio flux density g-ray spectral Index vs. radio luminosity

  20. X-radio-g Correlations • No significant correlation of X-ray/radio fluxes with g-ray fluxes of Fermi AGN

  21. Spectral index/redshift correlations • No evidence for K-correction effects (spectral softening > 1 GeV?)

  22. Comparison of Fermi and EGRET Fluxes • Fermi vs. EGRET

  23. Luminosity Function • Redshift-dependent luminosity function

  24. Implications • Calculation of luminosity density 1044 ergs Mpc-3 yr-1

  25. Fermi Blazars in the LBAS: Summary • ~90% success rate in correlating high-latitude bright Fermi sources with AGNs • Bright extragalactic g-ray sky dominated by radio-loud AGNs/blazars • Larger fraction of BL Lacs to total than found with EGRET • Much harder GeV spectra with BL Lacs (G 2.0) than FSRQs (G 2.40) • Mean redshifts of BL Lacs (z  0.1) vs. FSRQs (z  1) • Only ~30% of LBAS detected with EGRET • Only weak correlation between peak g-ray flux and radio flux density • V/Vmax test reveals strong positive evolution for FSRQs • Combined emission between (7 – 10) × 10-8 ph cm-2 s-1 make up ~7% of EGRET extragalactic unresolved background

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