1. Mid-Atlantic Radio-Loud AGN Meeting, 27 September 2013 , STScI
Radio-Loud AGNs as the Sources of the Ultra-High Energy Cosmic Rays
Chuck Dermer (NRL)
Naval Research Laboratory, Washington, DC
Recent work with
Matteo Cerruti (CfA), Catherine Boisson (LUTH), Andreas Zech (LUTH), Benoît Lott (CEN Bordeaux), Hajime Takami (KEK), Kohta Murase (IAS)
We argue in favor of the hypothesis that UHECRs are accelerated in the jets of blazars. This hypothesis explains a number of unusual observations, including extra gamma-ray spectral components; unusual weakly-variable TeV gamma-ray blazars, including 1ES and 1ES ; flattening of the Stecker-Scully relation between GeV-TeV spectral index and redshift; and VHE gamma-ray production in FSRQs. Joint CTA and Fermi analysis of VHE blazars like KUV can discriminate between photon-induced and UHECR-induced cascades. The search for gamma-ray echoes in the intergalactic magnetic field with strength B(IGMF) supports studies showing that B(IGMF) > 1e-18 G.
Mid-Atlantic Radio-Loud AGN Meeting, 27 September 2013 , STScI
Charles Dermer

2. Five Major Fermi/IACT Blazar Discoveries
Observer
Standard Blazar Model
Leptonic jet model:
Nonthermal synchrotron paradigm
Associated SSC and EC component(s)
Target photon sources:
Accretion-disk radiation
Broad-line region radiation
IR radiation from molecular torus q
BLR clouds G
Relativistically
Collimated
Plasma Jet
Dusty Torus
Five Major Fermi/IACT Blazar Discoveries W
Accretion
Disk
GeV spectral breaks in FSRQs, LSP/ISP blazars
3C 454.3
Rapid variability
Shorter than the BH dynamical timescale
VHE radiation from FSRQs
3C 279, 4C , PKS
Two classes of BL Lac objects
Strongly variable (Mrk 421, Mrk 501, PKS )
Weaky variable (1ES , , )
EBL/IGMF relationship
Extra component in EBL deabsorbed blazar SED (Finke et al. 2010)
Stecker-Scully relation
Measuring the IGMF
SMBH G
Ambient
Radiation
Fields

3. Equipartition Blazar Modeling
Use log-parabola function for electron distribution
From observations of Lsyn, nsyn, and tvar, derive parameters for B, Doppler factor dD, gpk , r’b
Use numerical model to adjust parameters to fit data, implying energy density of the external radiation field and (minimum) absolute jet power
Constrain location of the g-ray emission site
Explain GeV cutoff in FSRQs and LSP/ISP blazars
3-parameter model: amplitude K, curvature b, gp 3

4. Equipartition Relations
Assume (3-parameter) log-parabola function for electron distribution
Use observables and equipartition relations to derive G, B, gp , DR’b
log-parabola width
gives monoenergetic
electron specrum
Spectral Relation:
What does equipartition mean?
Equipartition
Relation: 4

5. Solution to System of Equations
Corrections for b ≠ 
Minimum jet power
Dermer et al. (2012) 5

6. FSRQ Modeling
1 GeV
Syn vs. EC beaming effect (Dermer 1995)

7. FSRQ Modeling: Dependence on b and tvar
1 GeV

8. BL Lac Modeling
Similar to SEDs of Mrk 421, Mrk 501, but not PKS ,
1ES , 1ES Contrary to flaring periods in Mrk 501

9. 3C 279 Model
Data from Hayashida et al. (2012)

10. 3C 279 Model
Data from Hayashida et al. (2012)

11. Implications External-field energy densities Jet Model
Normally t = 0.1, implies that emission region near outer edge of the BLR, ~ pc from SMBH
Jet Model
Colliding shells
Jet Power
Less than Eddington luminosity for MSMBH = (3-8)x108 Mo
Particle Acceleration
Second-order Fermi acceleration
Extra high-energy spectral component

12. GeV Spectral Cutoff Code improvements
Explain GeV spectral cutoff by scattering Ly a radiation (Cerruti et al. 2013)
Code improvements
Multi-line model
Thermal spectrum for dust radiation
(Ackermann et al. 2013)
(Telfer et al. 2002)
Electron distribution (Abdo et al. 2009)
gg absorption (Poutanen & Stern 2011)
Compton scattering model (Finke & Dermer 2011) 12

13. Spectral Fits to 3C 454.3
Cerruti et al. (2013)
Epoch A: August 2008 low state (Abdo et al. 2009)
Epoch B: November 2010 high state (Abdo et al. 2011; Wehrle et al. 2012) 13

14. UHECRs from Radio-Loud AGNs
HiRes Collaboration 2008
Auger Collaboration 2009
UHECRs from Radio-Loud AGNs
Standard one-zone synchrotron/SSC model
Parameters: B, d, R
Hillas condition:
UHECR sources must satisfy:
Extragalactic
Adequate energy production rate within GZK volume
Sources within GZK radius
UHECRs can escape from acceleration region
Mechanism to accelerate to ultra-high energies
Murase, Dermer, Takami, Migliori (2012)

15. Gamma-ray and Cosmic-ray Induced TeV emission from Jetted Sources
Weakly variable cascade radiation
lgg g g
n,e+ e+
p0, p p p g 2g
n,e- e-
~100 Mpc
~ Gpc
UHECR protons with energies ~1019 eV make ~1016 eV e that cascade in transit and Compton-scatter CMBR to TeV energies
Essey, Kalashev, Kusenko, Beacom (2010, 2011)

16. Electromagnetic Signatures of UHECRs
Photopair-induced cascade in IGM
Polisensky & Ricotti 2011
Murase et al. 2012

17. >10 GeV Sources Explained by Cascade Emission
Fermi-LAT analysis
Pass 7
> 10 GeV
Source class
ROI between 8 and 15 degrees
Use 2FGL source list to remove background sources
g-ray induced cascades
gg/Compton cascade
Use Kneiske et al. (2004) for low and best-fit EBL
Assume no suppression from IGMF ( G < BIGMF < G)
Intrinsic source spectrum F(Eg) Eg-s , 5.6 GeV < Eg < 100 TeV
UHECR-induced cascade
Bethe-Heitler pair production, photopair production, expansion
UHECR proton sources spectrum: F(Ep) ~ Ep-2.6exp(- Ep /Ep,c), Ep,c =1019 eV
Assume no suppression from IGMF (10-10 G < BIGMF for protons)
KUV (z = 0.61)
2 > 100 GeV g-rays within 0.2o
Takami, Murase, Dermer 2013
Normalization imposed to fit > 10 GeV Fermi-LAT spectrum from cascade emission 17

18. Predictions for CTA KUV 00311-1938 (z = 0.61) PG 1246+586 (z = 0.847)
Detected by HESS at 5.1s with 52.5 hrs observation (Stegmann 2012)
Lg > 3.5x 1046 erg/s
LUHECR >1.1 x1047 erg/s
PG (z = 0.847)
Not yet detected by TeV instrument
Lg > 7.5x1046 erg/s
LUHECR >2.0x1047 erg/s
Other sources detectable by 50 hour observations with CTA in the Neronov et al. (2012) list are Ton 116, B , 4C , and PKS
PG (z = 0.847) 18

19. Pair Production and Photohadronic Opacity in 4C +21.35
Inject ultra-relativistic leptons:
Dermer, Murase, Takami (2012)
Make synchrotron g-rays
Detection of GeV g rays  x >> 0.1pc →←

20. Dermer MARLAM 26 September 2013
Summary
Modeling
New equipartition technique for fitting blazar SEDs
Fits to 3C 279
Emission region at outer edge of BLR
Explain GeV cutoffs of 3C 454.3
UHECRs:
Blazars are the likely source of UHECRs, as can be tested with CTA
UHECRs from blazars would explain
extra high-energy spectral components
Stecker-Scully relation,
weakly variable BL Lac class
VHE g-ray production in FSRQs
Dermer MARLAM September 2013

21. EBL Effects on Blazar Spectra
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
Dermer et al. 2011
GeV-TeV Spectral Index Difference DG Stecker-Scully (2006, 2010) relation
Measurements of IGMF
(>~ G for persistent jet;
>~10-18 G for jet active for observing period)
Origin of hard component in deabsorbed BL Lac spectra? 21

22. Fermi Observations of 4C+21.35
PKS = 4C+21.35, z = 0.432
Fermi-LAT spectrum
Fermi LAT observations
Major flares 2010 April and June
sub-day scale variability
hour-scale variability (Foschini et al. 2011)
nFn peak at 1 – 10 GeV 22 22

23. GeV-TeV Connection 21 joint GeV-TeV sources
Abdo et al. (2009)
46 Extragalactic Sources listed in the VHE sky
Wagner’s catalog
Neronov et al. (2012) source catalog of 13 candidates of VHE emission at z > 0.5
EBL effects greater on more distant blazars
tgg(Ec,z) = 1 at Ec ≈ 100 GeV/z for 0.03 < z < 3
Model the >10 GeV Fermi-LAT emission by cascade g rays vs. cascades induced by UHECRs
Find minimum required jet powers and predictions for CTA
Neronov et al. 2012 23

24. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
VHE radiation from FSRQs
Two classes of BL Lac objects
EBL/IGMF relationships
LBAS, Abdo et al. 2009 24

25. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
VHE radiation from FSRQs
Two classes of BL Lac objects
EBL/IGMF relationship
3C 454.3
Abdo et al. 2009
Ackermann et al. 2010 25

26. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationships
MAGIC observations of Mrk 501
2005 July 9
Feb 2010 VERITAS OBS of MRK 421,
Albert et al. 2007 26

27. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
HESS obs. of
PKS
RS/c = 104M9 s
tvar ~ 5 min = 300 s
(?) M << 108 M0
28 July 2006 flare
Aharonian et al. 2007 27

28. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
Ackermann et al. 2010
3C 454.3 28

29. MAGIC Observations of PKS 1222+2163 = 4C+21.35
z = 0.432, flare of 17 June 2010
MAGIC spectrum
MAGIC observations
Emission over 30 minutes
Flaring on timescales of 10 minutes
Lg ~ 1047 erg/s (TeV energies)
Lg ~ 1048 erg/s (GeV energies)
Black hole mass: 1.5x108 Mo (Wang et al. 2004)
 extreme
MAGIC
light curve
G = 3.7
Fermi-LAT and
MAGIC spectrum
Aleksic et al. (2011)
Tanaka et al. (2011)

30. Five Big Fermi/IACT Blazar Discoveries
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
Mrk 421
Abdo et al. 2011a
Variable class
Mrk 421, Mrk 501
PKS
, etc.
Extreme sources
tvar < RS/c
Mrk 501
Abdo et al. 2011b 30

31. Five Big Fermi/IACT Blazar Discoveries
Mrk 421
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
Mrk 421
Mrk 421
tv = 4 d
Abdo et al. 2011a
B′=0.015G, d=12, R′=1.3x1017 cm
Abdo et al. 2011a
Abdo et al. 2011a
Variable class
Mrk 421, Mrk 501
PKS
Extreme sources
tvar < RS/c
SSC Model fits time-averaged emission
Mrk 501
B′=0.038G, d=21, R′=5.2x1016 cm
Mrk 501
tv = 1 d
Mrk 501
Abdo et al. 2011b
Abdo et al. 2011b
Abdo et al. 2011b 31

32. TeV BL Lac Objects Highly variable class Weakly variable class
Extreme sources
tvar < RS/c
SSC Model fits
Large inferred G factors
Weakly variable class
Weak Fermi LAT fluxes
GeV-TeV spectrum: EBL, IGMF
Mrk 421
Tavecchio et al. 2011
1ES z = 0.14
1ES z = 0.186
1ES z = 0.14
1ES z = 0.069
RGB J z = 0.08
Abdo et al. 2011b
Albert et al. 2007
Compton-scattered CMBR from
extended jet/lobe
Böttcher et al. 2008 32

33. GeV spectral breaks in FSRQs, LSP/ISP blazars Rapid variability
VHE g rays from FSRQs
GeV spectral breaks in FSRQs, LSP/ISP blazars
Rapid variability
Two classes of BL Lac objects
VHE radiation from FSRQs
EBL/IGMF relationship
Senturk et al. 2013
And PKS
With HESS and MAGIC 33