1. UHECRs from Black-Hole Jet Sources
Chuck Dermer
Space Science Division
US Naval Research Laboratory, Washington, DC
"Searching for the Origins of Cosmic Rays" Trondheim, Norway, June 15-18, 2009
Happy Birthday, Venya!

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

3. Outline Requirements for UHECR sources:
Extragalactic (but within the GZK radius)
Emissivity (>1044 erg Mpc-3 yr-1)
Power (> 1046 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)

4. GZK Horizon Distance for Protons
Horizon distance vs. MFP:
Linear distance where
proton with measured energy E had energy eE
CMBR only:
Auger
limits:
Auger finds that sources of UHECRs with energies > 60 EeV come from d < 75 Mpc
Correlsation with sources require that deflection in IGM field < 0.1 rad
GZK cutoff consistent
with UHECR protons
For model-dependent definition:
Harari, Mollerach, and Roulet 2006

5. UHECR Emissivity
knee
ankle

6. UHECR Emissivity
Yamamoto et al. (2007)
Sources of UHECRs need to have
a local luminosity density (emissivity) of 1044 erg/Mpc3-yr

7. UHECR Acceleration by Relativistic Jets
Proper frame (´) energy density of relativistic wind with apparent luminosity L x
Maximum particle energy G
Lorentz contraction 
DR´= G DR
R´= R/ G
What extragalactic sources have (apparent isotropic) L >> 1046 ergs s-1?
Those with (apparent isotropic) Lg > 1046 ergs s-1

8. Fermi Bright Sources (3 month source list)
Subset of LAT Bright Source List, 0FGL (Fermi Gamma-ray LAT):
Abdo et al. arXiv: (ApJ, in press)
LAT Bright AGN Sample (LBAS): Abdo et al. arXiv: (ApJ, in press)
0FGL: 205 LAT Bright Sources
Test Statistic > 100
Significance > 10s
132 |b|>10 sources
114 associated with AGNs
Compare EGRET:
31 >10s sources (total)
(10 at |b|>10)
August 4 – October 30, 2008

9. UHECRs from Radio Galaxies and Blazars
Cygnus A
FRII/FSRQ
L ~1045 x (f/10-10 ergs cm-2 s-1) ergs s-1
Mrk 421, z = 0.031
Fanaroff-Riley Classification:
Morphology correlates with radio power at 2x1025 W/Hz at 178 MHz ( 4x1040 ergs s-1), or total radio power of 1042 ergs s-1
Optical emission lines in FR IIs
brighter by an order of magnitude
than in FR Is for same galaxy
host brightness
FRI/BL Lac
3C 279, z = 0.538
FRI/II dividing
line at radio power
1042 ergs s-1
L ~5x1048 x (f/10-9 ergs cm-2 s-1) ergs s-1
3C 296
BL Lacs: optical emission line equivalent widths < 5 Å

10. Luminosity Density of Blazars
Minimum luminosity density of Radio Galaxies from LBAS
1044 ergs Mpc-3 yr-1

11. Cen A power: Bolometric radio luminosity: 4×1042 erg s-1
Centaurus A
~100 kpc × 500 kpc lobes
5e41 ergs/s in LBAS Gamma = 2.8
Need > 1046 erg s-1 apparent power to accelerate UHECR protons by Fermi processes
Cen A power: Bolometric radio luminosity: 4×1042 erg s-1
Gamma-ray power (from Fermi): 5×1041 erg s-1
Hard X-ray/soft g-ray power: 5×1042 erg s-1
UHECR power: few ×1040 erg s-1

12. What is Average Absolute Jet Power of Cen A?
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 Pj. Jet/counter-jet asymmetry gives outflow speed:
Hardcastle et al. 2009

13. Mean B-field and Average Absolute Jet Power in Cen A
Hardcastle et al. 2009
Pj(Cen A)  1044 erg s-1
Apparent jet power 100 x larger?

14. 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 GC
Hammer-Aitoff projection in galactic coordinates of UHECR arrival
directions and directions to nearby prominent AGN; the direction to the Galactic
Center is at the left and right extremities of this plot. Thick blue, red, and orange and
magenta circles correspond to UHECRs with > 56 EeV from Auger, > 56 EeV from
HiRes, and > 40 EeV from AGASA, respectively. The radii of the circles reflect the
angular errors in the reconstructed cosmic ray directions, which is 1◦ for both Auger
and HiRes and 1.8◦ for AGASA. The centers of the concentric green, purple and pink
circles correspond to the named AGN directions. The pink and purple circles represent
angular deflections from the source AGN of the arriving cosmic rays with 40 EeV and
20 EeV energies, respectively, in the µG galactic disk magnetic field, using eq. (2).
The green circles, on the other hand, represents angular deflection in an assumed 0.1
nG intergalactic magnetic field, assuming no magnetic-field reversals. The dashed and
dot-dashed curves correspond to the equatorial and super-galactic planes. z

15. UHECRs from Gamma Ray Bursts
GRB: Burst of g rays accompanying black-hole formation
Classes of GRBs
Long duration GRBs
(collapse of massive stellar core)
Short hard class of GRBs
(coalescence of compact objects)
Low luminosity GRBs
All-sky g ray map
in Galactic coordinates
(Galactic coordinates)
Long Duration GRBs
Found in Star Forming Galaxies
GRB/Supernova connection
Collapse to Newly Formed Black Hole
Prompt phase: internal or external relativistic shocks
Afterglow phase: external shock
Mean redshift: ~1 (BATSE), ~2 (Swift)
g-ray Light Curve of GRB
Swift mission discovered that short hard class of GRBs are related to old stellar populations (Gehrels et al. 2005)

16. GRB X-ray/g-ray Emissivity
GRB fluence:
> 20 keV fluence distribution of 1,973
BATSE GRBs (477 short GRBs and 1,496
long GRBs).
670 BATSE GRBs/yr (full sky)
Vietri 1995; Waxman 1995
(independent of beaming)
Baryon loading
(Band 2001)

17. Ultra-high Energy Cosmic Rays from Gamma Ray Bursts
Inject -2.2 spectrum of UHECR protons to E > 1020 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 (Berezinsky and colleagues)
Wick, Dermer, and Atoyan 2004
Test UHECR origin hypothesis by detailed fits to measured cosmic-ray spectrum

18. Effects of Different Star Formation Rates
g-ray signatures of UHECRs at source can
confirm this hypothesis
Hopkins & Beacom 2006

19. Fermi LAT GRBs as of
192 GBM GRBs
~30 short GRBs
8 LAT GRBs

20. Light Curves of GRBs 080825C, 081024B First LAT GRB. Note:
Preliminary
First LAT GRB. Note:
delayed onset of high-energy emission
extended (“long-lived”) high-energy g rays
First short GRB with >1 GeV photon detected

21. GRB 080916C: Luminous Fermi GRB
±30 deg region around GRB C
GRB at 48˚ from the LAT boresight at T0‏
RGB= <100 MeV, 100 MeV - 1 GeV, >1 GeV
Before the burst (T0-100 s to T0)‏
During the burst (T0 to T0+100 s)‏
Black region = out of FoV

22. GRB C: Notable Firsts
Largest number, ~145, of >100 MeV photons from a GRB
 Allows time-resolved spectral studies
First high-energy 100 MeV – GeV detection of a GRB with known redshift z =
4.35±0.2 from GROND photometry on 2.2 m in La Silla, Chile (Greiner et al. 2009)
Large fluence burst (2.4×10-4 ergs s-1) at 10 keV – 10 GeV energies
 Apparent isotropic energy release 8.8×1054 erg
 Supports the black-hole jet paradigm of GRB
Highest energy photon, E = GeV from a GRB with measured redshift
 Constraints on the jet Doppler factor/bulk Lorentz factor, emission region
 Implications for Extragalactic Background Light (EBL) models
 Limit on Quantum Gravity mass scale
Significant  4s delay between onset of >100 MeV and 100 keV radiation
 Implications for high-energy spectral modeling, leptonic/hadronic origin
Results published in Science (Abdo et al., vol. 323, issue 5922, page 1668, 2009)

23. Light Curves of GRB 080916C Again, two notable features:
8 keV – 260 keV
260 keV – 5 MeV
LAT raw
LAT > 100 MeV
LAT > 1 GeV T0
Again, two notable features:
Delayed onset of high-energy emission
Extended (“long-lived”) high-energy g rays
seen in both long duration and short hard GRBs

24. Interpretation of Delayed Onset of >100 MeV Emission
Random collisions between plasma shells
 Separate emission regions from forward/reverse shock systems
 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
Opacity effects
 Expansion of compact cloud, becoming
optically thin to >100 MeV photons
 Expect spectral softening break evolve
to higher energy in time, not observed
GRB C
Up-scattered cocoon emission
Synchrotron-self-Compton for < MeV
External Compton of cocoon photons, arriving
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
Razzaque, Dermer and Finke (2009)

25. Synchotron Radiation from UHE Protons
Instantaneous energy flux F (erg cm-2 s-1); variability time tv, redshift z
Implies a jet magnetic field
rb is baryon loading-parameter (particle vs. g-ray energy density)
xB gives relative energy density in magnetic field vs. particles
G > Gmin  103G3 from gg opacity arguments
Fluence (50-300): 3.4x10^-7 ergs.cm-2

26. Fermi Acceleration of Protons in GRB Blast Waves
Protons gain energy on timescales exceeding Larmor timescale,
implying acceleration rate
f is acceleration efficiency
Saturation Lorentz factor:
Proton saturation frequency (in mec2 units):
Observer measures a time
for protons to reach
Fluence (50-300): 3.4x10^-7 ergs.cm-2

27. Time for Proton Synchrotron Radiation to Brighten
gg processes induce second generation electron synchotron spectrum at
i.e., ~ 500 MeV for standard parameters
Time for proton synchrotron radiation to reach esat,e:
Fluence (50-300): 3.4x10^-7 ergs.cm-2

28. Long GRBs as the Sources of UHECRs
Maximum energy of escaping protons
Long GRB rate 2fb Gpc-3 yr-1 at the typical redshift z  1–2
10 smaller at 100d100 Mpc due to the star formation
fb > 200 larger due to a beaming factor
60E60 EeV UHECR deflected by an angle
IGM field with mean strength BnGnG coherence length of l1 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.

29. Extended High Energy Emission
GRB C
All LAT detected GRBs show significant
high energy emission extending after the
low energy emission has (almost)
disappeared below detectability
(discovered originally with EGRET on
Compton Observatory; Hurley et al. 1994)
GRB080916C shows HE emission that
extends more than 1000 sec. beyond the
detectable keV-MeV emission
Could be due to …
Delayed arrival of Compton-scattered synchrotron photons (SSC)
Though no hard spectrum observed as expected from SSC, unknown reason for delay
Emission from >TeV -ray induced cascade in CMB (e.g., Razzaque, Meszaros & Zhang 2004)
Requires very small (<10-16 G) intergalactic magnetic field
Long-lived hadronic emissions (Böttcher and Dermer 1998)
Abdo et al., Science, 323, 1668 (2009)

30. Ruled out: Viable: UHECRs accelerated by black-hole jets
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, topological defects
Clusters of galaxies
Viable:
Jets of AGNs: radio-loud or radio-quiet? Cen A!, M87?
GRBs:
Magnetars? Others?
Requires nano-Gauss intergalactic magnetic field
UHECRs accelerated by black-hole jets

31. Neutral Beam Model for UHECRs in Blazars
Possible photon targets for p +:
Internal: synchrotron radiation
External: accretion disk radiation (UV)
(i) direct accretion disk radiation:
(ii) accretion disk radiation scattered in the broad-line region (Atoyan & Dermer 2001)
quasi-isotropic, up to RBLR~ pc
Impact of the external accretion-disk radiation component:
high p-rates & lower threshold energies:
=7 (solid)
=10 (dashed)
=15 (dot-dashed)
(red - without ADR)
(for flare of 3C 279)

32. Blazars as High Energy Hadron Accelerators
Powerful blazars / FR-II
Neutrons with En > 100 PeV and rays with E > 1 PeV take away
~ 5-10 % of the total energy injected at R<RBLR
(3C 279)
Synchrotron and IC fluxes from the pair-photon cascade for the Feb flare of 3C279
dotted - CRs injected during the flare;
solid - neutrons escaping from the blob,
dashed - neutrons escaping from Broad Line Region (ext. UV)
dot-dashed - g rays escaping external UV field (from neutrons outside the blob)
3dot-dashed- Protons remaining in the blob at l = RBLR
astro-ph/
Sreekumar et al. (1998)

33. Hadronic g-Ray Emission from Blazars
Gamma rays from hadron-induced cascades: Orphan g-ray flares

34. Neutrinos: Predicted Fluences/Numbers
Expected  - fluences calculated for 2 flares, in 3C 279 and Mkn 501, assuming
proton aceleration rate Qprot(acc) = Lrad(obs) ; red curves - contribution due to
internal photons, green curves - external component (Atoyan & Dermer 2003)
Expected numbers of  for IceCube-scale detectors, per flare:
3C 279: N = for  = 6 (solid curve) and N = for  = 6 (dashed)
Mkn501: N = for  = 10 (solid) and N = 10-5 for  = 25 (dashed)
(`persistent')  -level of 3C279 ~ 0.1 F (flare) , ( + external UV for p )
 N ~ few - several per year can be expected from poweful HE  FSRQ blazars.

35. energy and momentum transport from AGN core
UHE neutrons and  rays
energy and momentum transport from AGN core
UHE -ray pathlengths in CMBR:
l ~ 10 kpc - 1Mpc
for En ~ eV
Neutron decay pathlength:
ld (n) = 0 c n (0 ~ 900 s)
 ld ~ 1 kpc – 1 Mpc
for E ~ eV
solid: z = 0
dashed: z = 0.5

36. Pictor A l jet ~ 1 Mpc (lproj = 240 kpc) Deposition of energy through
d ~ 200 Mpc
l jet ~ 1 Mpc (lproj = 240 kpc)
Deposition of energy through
ultra-high energy neutral beams (Atoyan and Dermer 2003)
Pictor A in X-rays and radio (Wilson et al, 2001)

37. Hadronic GRB Modeling in Collapsar Scenario
Nonthermal Baryon Loading Factor fb = 30
Energy injected in protons normalized to GRB synchrotron
fluence
Injected proton
distribution
Cooled proton
distribution
Forms neutral beam of neutrons, g rays, and neutrinos
Escaping neutron
distribution

38. Photon and Neutrino Fluence during Prompt Phase
Nonthermal Baryon
Loading Factor fb = 1
Ftot = 310-4 ergs cm-2
dD = 100
Hard g-ray emission component from hadronic-induced electromagnetic cascade radiation inside GRB blast wave
Second component from outflowing high-energy neutral beam of neutrons, g-rays, and neutrinos