1. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang1 Fermi-LAT Observations of Blazars Jim Chiang SLAC/KIPAC on behalf of the Fermi-LAT collaboration

2. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang2 Related Talks on Fermi-LAT Results Markus Ackermann – Observation of the extragalactic diffuse continuum gamma-ray emission with Fermi LAT Keith Bechtol – GeV gamma-ray observations of galaxy clusters with the Fermi LAT Chuck Dermer – Evidence for ultrahigh energy cosmic rays from Fermi obsevations of AGN and gamma ray bursts David Paneque – Fermi view of the classical TeV high peak BL Lacs Greg Madejski – Gamma-ray spectra of blazars detected by Fermi/LAT Marco Ajello – Cosmological evolution of blazars: new findings from the Swift/BAT and Fermi/LAT surveys

3. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang3 Unified Picture of AGNs Powered by accretion onto a central, supermassive black hole Accretion disks produce optical/UV/X-ray emission via various thermal processes Jets: highly collimated outflows with  10 –Large brightness temps, superluminal motion, rapid variability in  -rays Unified Model: observer line-of- sight determines source properties, e.g., radio galaxy vs blazar Other factors: accretion rate, BH mass and spin, host galaxy Image Credit: C.M.Urry & P. Padovani

4. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang4 Blazar Spectral Energy Distributions Two main components: –Synchrotron at low energies –Inverse Compton and/or “hadronic” at higher energies Flat Spectrum Radio Quasars (FSRQs) –Multi-temperature disk emission and broad lines in OUV –Non-thermal components peak in IR & hard X-ray/MeV regime –Higher luminosity (L iso  10 48 erg s  1 ) and redshift dist. peaks at z  1 BL Lac objects –Little or no evidence of disk or broad emission lines (EW < 5Å) –Non-thermal peaks in UV/soft X-rays & GeV –Lower luminosity (L iso  10 45 erg s  1 ) and z < 0.5 3C 279 Hartman et al. 2001 Mrk 421 Donnarumma et al. 2009

5. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang5 Key Questions for Blazars Emission mechanisms (especially for high energy component) –Leptonic (IC of synchrotron or external photons) vs hadronic (  0 , proton synchrotron) Emission location –Single zone for all wavebands (completely constraining for simplest leptonic models) –Opacity effects and energy-dependent photospheres Particle acceleration mechanisms –Shocks, Blandford-Znajek Jet composition –Poynting flux, leptonic, ions Jet confinement –External pressure, magnetic stresses Accretion disk—black hole—jet connection Blazars as probes of the extragalactic background light (EBL) Effect of blazar emission on host galaxies and galaxy clusters

6. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang6 What is Fermi? Large leap in all key capabilities, transforming our knowledge of the gamma-ray universe. Great discovery potential. Large Area Telescope (LAT): 20 MeV - >300 GeV (including unexplored region 10-100 GeV) 2.4 sr FoV (scans entire sky every ~3hrs) Gamma-ray Burst Monitor (GBM) 8 keV - 40 MeV views entire unocculted sky Launch 11 June 2008!

7. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang7 Fermi LAT Overview: Overall Design e+e+ e–e–  Precision Si-strip Tracker: Measures incident gamma direction 18 XY tracking planes. 228 mm pitch. High efficiency. Good position resolution 12 x 0.03 X0 front end => reduce multiple scattering. 4 x 0.18 X0 back-end => increase sensitivity >1GeV Electronics System: Includes flexible, highly-efficient, multi-level trigger Hodoscopic CsI Calorimeter: Segmented array of 1536 CsI(Tl) crystals 8.5 X0: shower max contained <100 GeV Measures the incident gamma energy Rejects cosmic ray backgrounds Anticoincidence Detector: 89 scintillator tiles First step in reduction of large charged cosmic ray background Segmentation reduces self veto at high energy Overall LAT Design: 4x4 array of identical towers 3000 kg, 650 W (allocation) 1.8 m  1.8 m  1.0 m 20 MeV – >300 GeV Thermal Blanket: And micro-meteorite shield

8. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang8 3 Month Counts Map

9. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang9 3 Month High Confidence Source List 205 sources with significance > 10  (EGRET found fewer than 30) Typical 95% CL error radius is <10 arcmin (Abdo et al. 2009 ApJS, 183, 46)

10. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang10 Variable sources in the LAT Bright Source List Based on 1 week time scales 68/205 show variability with probability > 99% Isotropic distribution  blazars

11. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang11 Fermi Results for Individual AGNs 3C 454.3 PKS 1502+106 PKS 2155  304 NGC 1275 PKS 1454  354 PMN J0948+002

12. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang12 3C 454.3 OVV quasar, very active since 2000; z = 0.859; superluminal motion Variability time scales of 6 (cf.  VLBI  25) First definitive evidence of a spectral break above 100 MeV  =1.2 > 0.5  not from radiative cooling Possible explanations: –“intrinsic” absorption via  opacity from accretion disk or BLR photons –feature in the underlying particle distribution Implications for EBL studies and blazar contribution to extragalactic diffuse emission  =2.3  =3.5 (contact authors: G. Madejski & B. Lott)

13. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang13 PKS 2155  304: The Campaign PKS 2155-304: HBL, z=0.116 –Detectable by HESS routinely in < 1 h even in low state (  0.1 Crab) –July 2006 flare:  7 Crab, VHE strongly correlated with X-rays, an SSC prediction; but  t ~ 5min poses difficulties for SSC models Our Campaign: 11 nightly obs. using HESS, ATOM, RXTE (+ Swift) –First multiwaveband observations of a blazar SED using Fermi and an ACT –Monitor for very high state outburst similar to the July 2006 flare seen by HESS (Swift ToO) –Study correlated variability between various bands Aharonian et al. 2007

14. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang14 PKS 2155  304: Spectral Energy Distribution Time-averaged SED is well described by a single zone SSC model: HESS Fermi RXTE Swift ATOM p 0 =1.3 p 1 =3.2 p 2 =4.3 e + e  distribution Highest energy electrons (  e >2  10 5 ) produce the X-ray emission, but contribute relatively little above 0.2 TeV (contact authors: B. Giebels & J. Chiang)

15. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang15 PKS 2155  304: Light Curves and Correlated Variability X-ray and VHE fluxes are not correlated, in contrast to July 2006 flare Lack of spectral variability in HESS band (  VHE < 0.2)  weak radiative cooling regime Significant spectral variability in X-rays (  X  0.5)  strong cooling regime  Electrons producing the X- rays have higher energies than those producing the TeV Optical and VHE fluxes are correlated  Optical is driving the TeV variability Lack of opt-GeV correlation Multi-zone SSC models are required

16. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang16 NGC 1275 (3C 84, Perseus A) Classic example of a “cooling core” cluster Voids or “bubble” seen in the X-ray must be inflated by some central source of power, i.e., an AGN LAT counts map, > 200MeV, 4 Aug - 5 Dec 100 arcsec across (contact author: J. Kataoka)

17. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang17 Fermi-LAT detection of NGC 1275 Variable emission on month to year time scales  AGN Cannot be dark matter or diffuse cluster emission Inferred blazar luminosity, L   10 44 -10 45 erg s  1, is consistent with power needed to inflate the voids SED fitted with single zone SSC model (solid curve) and spine- sheath model (dashed) COS-B EGRET Fermi

18. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang18 Optical spectrum of narrow-line Seyfert 1 type (usually radio quiet). Radio emission is strongly variable and with flat spectrum  suggests Doppler boosting, now confirmed by LAT. First  -ray detection of such an object SED modeling shows this is a typical FSRQ, although with a relatively low power. Is this a new type of  -ray emitting AGN? Are there other sources of this type? What is the impact of narrow-lines? (Abdo, et al 2009 ApJ, 699, 976. Contact author: L. Foschini) Narrow-Line Seyfert 1 PMN J0948+0022

19. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang19 Blazar Population Properties Aug/Sep/Oct high confidence list: 205 sources with >10  detection 132 with |b| > 10  (7 pulsars, 9 unid) –116/125 are bright, flat spectrum radio sources –58 FRSQs, 42 BL Lacs, 4 Unc., 2 radio galaxies (+10 low CL associations) –CRATES (all-sky radio catalog), CGRaBS (all-sky optical spectra), BZCAT (multifrequency blazar catalog) FSRQ BL Lac Radio Galaxy Uncertain arXiv:0902.1559 Abdo et al, ApJ in press

20. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang20 Photon index FSRQs F BLLacs FRSQs BL Lacs All  =2.4  0.2  =2.0  0.2 FSRQ and BL Lac index distributions differ at 1  10  12 level 42% BL Lac fraction (vs 23% for EGRET), 10 HBLs 8 TeV Blazars Blazar Population Properties

21. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang21 Blazar Population Properties b = 20 , 80  E < 3 GeV b = 20  BL Lacs FSRQs

22. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang22 Luminosity vs Redshift F >100MeV = 4  10  8 ph cm  2 s  1

23. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang23 Luminosity Functions FSRQs –Strong evolution –More complicated than pure density or pure luminosity evolution –The 3 month LAT AGN sample measures the bright end of the luminosity distribution BL Lac objects –No evidence of evolution Combined emission from individual blazars in 3 month sample corresponds to 7% of EGRET extragalactic diffuse (contact: M. Ajello) L  0.5 L  1.5 L  1.1

24. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang24 Conclusions The LAT is performing spectacularly well, both operationally and scientifically. Several multiwavelength campaigns have been completed and others are on-going.  Many more papers on individual blazars are forthcoming. The LAT team is busy performing detailed spectral and variability studies for a deeper sample of AGNs utilizing the full 1 st year dataset. We are undertaking population studies relating the LAT blazar properties to radio, optical, X-ray, and TeV observations. Current results on AGNs are just the tip of the iceberg.

25. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang25 Backup slides

26. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang26 Measuring the EBL with Fermi Blazars The effects of EBL absorption will occur at lower energies for higher redshift sources Blazars with z > 1 will begin to show these effects in the LAT band: Credit: L. Reyes

27. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang27 Outline Blazar Properties and Fundamental Questions Fermi LAT Capabilities Multiwavelength Campaigns Results on Individual Sources Population Studies and Extragalactic Diffuse Emission Summary

28. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang28 The Fermi Large Area Telescope Launched 11 June 2008 2.4 sr FOV First year survey mod operation:  35  rocking about orbital plane each orbit  full sky coverage every 3 hours Energy range: 20 MeV to >300 GeV,  E/E  10–15 %

29. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang29 Publicly Monitored Source List ? Awaiting definitive detection by LAT † TeV source ? ? ? † google: LAT_Monitored_Sources

30. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang30 Source Monitoring Activities Automated Science Processing (ASP) –Transient detection: Source detection algorithm to find all point sources in data from each epoch (6hr, day, week) –Follow-up monitoring: Full likelihood analysis on sources from transient detection step + “publicly monitored” sources –2  10  6 ph cm  2 s  1 threshold (day time scale) for public release of others Flare Advocates: –LAT scientists from Galactic and Extragalactic groups examine ASP output and perform follow-up analyses, produce ATels, and propose ToOs 3C 454.3

31. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang31 Announcements of flaring sources  multiwavelength follow-up 25 blazar-related LAT ATELs have been issued on 22 different sources

32. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang32 Multiwavelength Campaigns 3C 454.3: Jul–Oct; radio, opt, UV, Swift BL Lac: 15 Aug–5 Sep; opt, UV, X-ray PKS 2155-304: 25 Aug–6 Sep; radio, opt, UV, X-ray, TeV (HESS) 1ES 1959+650: Sep–Nov PKS 0528+134: 27 Sep–Oct; radio, IR, opt, UV, X-ray 3C 273: 31 Oct–7 Feb; radio, opt, X-ray 3C 279: Aug—Mar; radio, opt, X-ray, TeV Mrk 421: Jan–May; radio, opt, X-ray, TeV (VERITAS, MAGIC)

33. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang33 Flaring Blazars PKS 1502+106: z=1.84, factor 3 increase in <12 hrs, highest  L/  t in GeV band PKS 1454  354: factor  5 increase of >100 MeV flux in 12 hours; achromatic flux variations  weak radiative cooling regime, GeV variability driven by seed photon changes (cf. PKS 2155  304) Preliminary (contact author: L. Foschini) (contact author: S. Ciprini)

34. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang34 Fermi Radio Galaxy Detections Cen A NGC1275 (Perseus A) 3 month all-sky map Confirmed EGRET detection of Cen A NGC 1275 consistent with point source and no significant variability within initial four month span of LAT Observations Abdo et al.2009 ApJ Contact Author: J.Kataoka

35. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang35 NGC1275: Long Term  -ray variability & Correlation with Radio? LAT flux 6x brighter than EGRET limit Historical COS-B detection while radio in high radio state Radio light curve rising during the Fermi observations with pc-scale outburst seen in MOJAVE maps Contours: Aug ‘08 VLBA 15 GHz Color: Sep ‘07 map subtracted From MOJAVE program

36. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang36 Spectral Energy Distribution SED LBL-like: possible unification of BL Lac and Radio Galaxies LAT spectrum: 0 ) -   = 2.17 ± 0.05 (1) one-zone SSC B= 0.05 G R= 0.7 pc  = 2.3,  = 1.8 L jet = 2.3e45 erg/s (2) Decelerating flow B = 0.2 G D = 0.2 pc R = 0.01 pc  = 10 -> 2 L jet = 6.0e43 erg/s Jet power close to the power required to inflate the lobes of 3C 84 against the pressure of the hot cluster gas (0.3-1.2)x 10 44 erg/s: Dunn & Fabian 2004

37. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang37 LAT Detection of a Narrow Line Seyfert 1 Seyfert galaxies are not normally associated with blazar emission PMN J0948+0022 SED is similar to an FSRQ’s, but at much lower luminosity Seyfert galaxies have lower mass BHs (  10 7 M sun ) & NS1s have high accretion rates  Eddington ratio is a key determinant of SED characteristics Peak  -ray flux vs 8.4 GHz flux (contact author: L. Foschini)

38. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang38 Gamma-ray vs Radio Properties Peak  -ray flux vs 8.4 GHz flux density  -ray photon index vs radio luminosity

39. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang39 Astronomer’s Telegrams* #1628, 24 Jul 2008, 3C 454.3, z=0.859, FSRQ #1650, 8 Aug 2008, PKS 1502+106, z=1.84, FSRQ #1701, 5 Sep 2008, PKS 1454-354, z=1.42, FSRQ #1707, 8 Sep 2008, 3C 273, z=0.158, FSRQ #1743, 26 Sep 2008, PKS 1510-089, z=0.360, FSRQ #1744, 26 Sep 2008, AO0235+164, z=0.940, BL Lac #1759, 3 Oct 2008, 3C 66A, z=0.44?, IBL (VERITAS Atel 1753) #1759, 3 Oct 2008, PKS 0208-512, z=0.999 #1759, 3 Oct 2008, PKS 0537-441, z=0.894, BL Lac #1784, 15 Oct 2008, AO0235+164, z=0.940, BL Lac #1864, 6 Dec 2008, 3C 279, z=0.536, FSRQ #1877, 16 Dec 2008, QSO B0133+47, z=0.859 #1888, 4 Jan 2009, CRATES J1239+0443 (3EGJ1236+0457), z=1.76? #1894, 8 Jan 2009, PKS 1244-255, z=0.64, FSRQ #1897, 9 Jan 2009, PKS 1510-089, z=0.360, FSRQ * blazar-only

40. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang40 Blazar Population Properties FRSQsBL Lacs

41. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang41 Blazar Population Properties 34% BL Lac fraction (vs 19% for EGRET)

42. Fermi-LAT Observations of Blazars TeVPA, SLAC, 14 July 2009 J. Chiang42 Blazar Population Properties b = 20 , 80  E < 3 GeV b = 20 