1 Evidence for UHECR Acceleration from Fermi Observations of AGNs and GRBs Chuck Dermer Space Science Division US Naval Research Laboratory, Washington, DC TeV Particle Astrophysics 2009 SLAC, July 13-17, 2009

2 Outline  Requirements for UHECR sources: –Extragalactic (but within the GZK radius) –Emissivity (>10 44 erg Mpc -3 yr -1 ) –Apparent Isotropic Power (> few×10 45 erg s -1 ) (for Fermi acceleration)  Extragalactic Gamma Ray Sources from Fermi  Radio Galaxies and Blazars as Sources of the UHECRs  Gamma-Ray Bursts as Sources of the UHECRs Dermer, Razzaque, Finke, Atoyan (New Journal of Physics, 2009) Razzaque, Dermer, Finke (Nature Physics, submitted, 2009) Dermer and Menon, “High Energy Radiation from Black Holes: Gamma Rays, Cosmic Rays, and Neutrinos” (Princeton University Press, 2009)

3 Black-Hole Jet Sources of UHECRs Nonthermal  rays  relativistic particles + intense photon fields Leptonic jet model: radio/optical/ X- rays: nonthermal lepton synchrotron radiation Hadronic jet model:  Photomeson production second  -ray component p  →  → ,, n Neutrons escape to decay and become UHECR protons (Neutral beam model: Atoyan & Dermer 2003) Large Doppler factors required for  rays to escape Photopair/photopion vs. ion synchrotron

4 GZK Horizon Distance for Protons Horizon distance vs. MFP: Linear distance where proton with measured energy E had energy eE For model-dependent definition: Harari, Mollerach, and Roulet 2006 CMBR only: GZK cutoff consistent with UHECR protons Auger limits:

5 UHECR Emissivity knee ankle (Waxman 1995)

6 UHECR Acceleration by Relativistic Jets x  Proper frame (´) energy density of relativistic wind with apparent luminosity L Lorentz contraction   R ´=  R R ´= R/  Maximum particle energy What extragalactic sources have (apparent isotropic) L /  2 >> ergs s -1 ? Those with (apparent isotropic) L  > ergs s -1

7  LAT Bright AGN Sample (LBAS): Abdo et al. arXiv: (ApJ, 2009)arXiv: month catalog:August 4 – October 30, FGL: 205 LAT Bright Sources Test Statistic > 100 Significance > 10  132 |b|>10  sources 114 associated with AGNs Compare EGRET: 31 >10  sources (total) (10 at |b|>10  ) Fermi AGNs reviewed by Jim Chiang, Greg Madejski, D. Paneque UHECRs from Blazars 11 mo. Source List!

8 Luminosity Distribution vs. Redshift Abdo et al., ApJS (2009) (Cen A (>100 MeV) few×10 41 erg/s) GZK horizon For sources within GZK radius, need > 10 3 persistent sources per Gpc 3

9  Minimum luminosity density of Radio Galaxies from LBAS Luminosity Density of  -ray Blazars ergs Mpc -3 yr -1 (5×10 40 erg/s w/i 3.5 Mpc)

10 Centaurus A Need >> erg s -1 apparent power to accelerate UHECR protons by Fermi processes Cen A power: Bolometric radio luminosity: 4×10 42 erg s -1 Gamma-ray power (from Fermi): few ×10 41 erg s -1 Hard X-ray/soft  -ray power: 5×10 42 erg s -1 UHECR power: few ×10 40 erg s -1 ~100 kpc × 500 kpc lobes

11 What is Average Absolute Jet Power of Cen A? Hardcastle et al Total energy and lifetime: Cocoon dynamics (Begelman and Cioffi 1989 for Cyg A) Use synchrotron theory to determine minimum energy B field, absolute jet power P j. Jet/counter- jet asymmetry gives outflow speed: Dermer, Razzaque, Finke, Atoyan, NJP 09 Celotti and Fabian 93

12 Mean B-field and Average Absolute Jet Power in Cen A Hardcastle et al P j (Cen A)  erg s -1 Apparent jet power 20 x larger?

13 Search for UHECRs Enhancements from Radio Galaxies and Blazars Blue: Auger, > 56 EeV (1 ◦ ) Red: HiRes > 56 EeV (1 ◦ ) Magenta: AGASA, > 56 EeV (1.8 ◦ ) Orange: AGASA, EeV (1.8 ◦ ) Pink and purple circles: angular deflections of UHECRs with 40 EeV and 20 EeV from source AGN, respectively, in the galactic disk magnetic field. Green circles represent angular deflections in assumed 0.1 nG intergalactic magnetic field, assuming no magnetic-field reversals. GC MW magnetic deflection  UHECR protons If blazars accelerate UHECR protons, then mean IGM field

14 > 20 keV fluence distribution of 1,973 BATSE GRBs (477 short GRBs and 1,496 long GRBs). 670 BATSE GRBs/yr (full sky) UHECRs from Gamma Ray Bursts GRB fluence: Vietri 1995; Waxman 1995 (Band 2001) (independent of beaming) Baryon loading Luminosity density of GRBs

15 Wick, Dermer, and Atoyan 2004 UHECR Spectrum from Long-Duration GRBs  Inject  2.2 spectrum of UHECR protons to E > eV  Injection rate density determined by birth rate of GRBs early in the history of the universe  High-energy (GZK) cutoff from photopion interactions with cosmic microwave radiation photons  Ankle formed by pair production effects (Berezinskii, Gazizov, Grigoreva) Test UHECR origin hypothesis by detailed fits to measured cosmic-ray spectrum

16 Effects of Different Star Formation Rates Hopkins & Beacom 2006  -ray and signatures of UHECRs at source tests GRB source hypothesis

Light Curves of GRBs C, B First LAT GRB. Note: delayed onset of high-energy emission extended (“long-lived”) high-energy  rays Preliminary First short GRB with >1 GeV photon detected (Fermi GRBs reviewed by H. Tajima)

Light Curves of GRB C Again, two notable features: 1.Delayed onset of high-energy emission 2.Extended (“long-lived”) high-energy  rays seen in both long duration and short hard GRBs 8 keV – 260 keV 260 keV – 5 MeV LAT raw LAT > 100 MeV LAT > 1 GeV T0T0

19 Interpretation of Delayed Onset of >100 MeV Emission Razzaque, Dermer and Finke (2009)  Random collisions between plasma shells  Separate emission regions from forward/reverse shock systems  Separate emission regions from forward/reverse shock systems  Second pair of colliding shells produce, by chance, a harder spectrum  Second pair of colliding shells produce, by chance, a harder spectrum  Expect no time delays for >100 MeV in some GRBs, yet to be detected  Expect no time delays for >100 MeV in some GRBs, yet to be detected  Opacity effects  Expansion of compact cloud, becoming  Expansion of compact cloud, becoming optically thin to >100 MeV photons optically thin to >100 MeV photons  Expect spectral softening break evolve  Expect spectral softening break evolve to higher energy in time, not observed to higher energy in time, not observed  Up-scattered cocoon emission Synchrotron-self-Compton for < MeV Synchrotron-self-Compton for < MeV External Compton of cocoon photons, arriving External Compton of cocoon photons, arriving late from high-latitude, to >100 MeV late from high-latitude, to >100 MeV Toma, Wu, Meszaros (2009)  Proton synchrotron radiation Inherent delay to build-up proton synchrotron flux which sweeps into LAT energy range from high-energy end GRB C

20 Synchotron Radiation from UHE Protons Instantaneous energy flux  (erg cm -2 s -1 ); variability time t v, redshift z Implies a jet magnetic field  b is baryon loading-parameter (particle vs.  -ray energy density)  B gives relative energy density in magnetic field vs. particles  >  min  10 3  3 from  opacity arguments

21 Fermi Acceleration of Protons in GRB Blast Waves Protons gain energy on timescales exceeding Larmor timescale, implying acceleration rate  is acceleration efficiency Saturation Lorentz factor: Proton saturation frequency (in m e c 2 units): Observer measures a time for protons to reach

22 Time for Proton Synchrotron Radiation to Brighten  processes induce second generation electron synchotron spectrum at i.e., ~ 500 MeV for standard parameters Time for proton synchrotron radiation to reach  sat,e :

23 Long GRBs as the Sources of UHECRs  Maximum energy of escaping protons  Long GRB rate  2f b Gpc -3 yr -1 at the typical redshift z  1–2  10 smaller at  100d 100 Mpc due to the star formation f b > 200 larger due to a beaming factor  60E 60 EeV UHECR deflected by an angle IGM field with mean strength B nG nG coherence length of 1 Mpc  Number of GRB sources within  100 Mpc with jets pointing within 4  of our line-of-sight is  If typical long duration GRBs have a narrow core accelerating UHECRs, then GRBs could account for Auger events within GZK radius.

24 Extended High Energy Emission  LAT detected GRBs show significant high energy emission extending after the high energy emission extending after the GBM emission returns to background GBM emission returns to background (discovered originally with EGRET on Compton Observatory; Hurley et al ) Compton Observatory; Hurley et al )  Could be due to …  Delayed arrival of SSC  Long-lived hadronic emissions  Long-lived hadronic emissions (Böttcher and Dermer 1998) Abdo et al., Science (2009) GRB C  Injection problem  Internal shells  External shock  extended (> cm) wind/shell Greiner et al., A&A (2009)

25 UHECR Origin Ruled out: Galactic sources young neutron stars or pulsars, black holes, GRBs in the Galaxy Particle physics sources superheavy dark matter particles in galactic halo top-down models Clusters of galaxies Viable: Jets of AGNs: radio-loud or radio-quiet? Cen A!, M87?  nG IGM magnetic field (long) GRBs: Requires nano-Gauss intergalactic magnetic field UHECRs accelerated by black-hole jets Auger UHECR arrival directions correlated with matter within 100 Mpc

26 Sreekumar et al. (1998) Unresolved  -Ray Background Strong, Moskalenko, & Reimer (2000) Data: Star-forming galaxies (Pavlidou & Fields 2002) Starburst galaxies (Thompson et al. 2006) Galaxy cluster shocks ( Keshet et al. 2003, Blasi Gabici & Brunetti 2007) BL Lacs: ~2 - 4% (at 1 GeV) FSRQs: ~ % Dermer (2007) Thermal black holes Nonthermal black holes (accretion) (jet)

Fermi LAT GRBs as of GBM GRBs ~30 short GRBs 8 LAT GRBs (reviewed by H. Tajima, this conference) (distinguish long vs. short GBM GRBs)