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High Energy Emission in Extragalactic Nonblazar Sources Chuck Dermer U.S. Naval Research Laboratory July 4, 2006 Multi-Messenger Approach to Unidentified Gamma-Ray Sources Barcelona, Spain Armen Atoyan U. de Montréal Markus Böttcher Ohio University Jim Chiang UMBC/GSFC Bob Berrington University of Wyoming Catalog of Established High Energy (> 100 MeV) Gamma-Ray Sources Solar System: 1. Sun/Solar Flares (1) Galaxy: 1. Pulsars (~8) 2. SNRs/Diffuse cosmic-ray induced radiations (~10) 3. High-mass microquasars (2) 4. Pulsar Wind Nebulae and X-ray Binaries (~dozen) Extragalactic: 1. Diffuse CR emissions (LMC) 2. Blazars + Radio Galaxies (Cen A, M87) (~100 + 2) 3. GRBs (~8) 3. Clusters of Galaxies? 4. Dark Matter Emission?? EGRET Unidentified Sources (~170) HESS/TeV Unidentified Sources (>15) GLAST Unidentified Sources (tbd) Outline Gamma Ray Bursts: 1. Observations Evidence for Multiple Components: Results from EGRET and BATSE Rapid X-ray Declines Discovered with Swift 2. 3. 4. 5. Blast Wave Model: Leptonic Processes Blast Wave Model: Hadronic Processes GRB/Cosmic Ray/g-ray/Neutrino Connection SGRBs Clusters of Galaxies: 1. 2. 3. Merger and Accretion Shocks Spectral Analysis Predictions 1. Gamma Ray Bursts subsecond variability GRB 940217 Long (>90 min) g-ray emission (Hurley et al. 1994) GRB 940217 Nonthermal processes Two components seen in two epochs MeV synchrotron and GeV/TeV SSC g-g lower limit to the Two components seen in two separate epochs bulk Lorentz factor How to explain the two components? G of the outflow How to explain the two components? Anomalous High-Energy Emission Components in GRBs Evidence for Second Component from BATSE/TASC Analysis −18 s – 14 s 1 MeV 14 s – 47 s 47 s – 80 s 80 s – 113 s Hard (-1 photon spectral index) spectrum during delayed phase 113 s – 211 s GRB 941017 (González et al. 2003) 100 MeV Second Gamma-ray Component in GRBs: Other Evidence Atkins et al. 2002 Bromm & Schaefer 1999 (Requires low-redshift GRB to avoid attenuation by diffuse IR background) Delayed high-energy g-ray emission from superbowl burst Seven GRBs detected with EGRET either during prompt MeV burst emission or after MeV emission has decayed away (Dingus et al. 1998) Average spectrum of 4 GRBs detected over 200 s time interval from start of BATSE emission with photon index 1.95 (0.25) (> 30 MeV) Swift Observations of Rapid X-Ray Temporal Decays Tagliaferri et al. (2005) O’Brien et al. (2006) Opacity Constraints: Lower Limits to G GRBgg 940217 Nonthermal processes Two components seen in two epochs MeV synchrotron and GeV/TeV SSC g-g lower limit to the bulk Lorentz factor G of the outflow How to explain the two components? Nonthermal g-Ray Emission: gg Transparency Argument for Bulk Relativistic Motion In comoving frame, avoiding threshold condition for gg interactions requires 1 1; Peak Flux : 10-6 f -6 ergs cm -2 s -1 Requirement that gg optical depth be less than unity: T 2 ' 2 ctv gg ( ' )n ph ( ' ) rb , rb 3 1 1 (1 z ) 200 [(1 z )d 28 ] 1/ 3 f -6 E (GeV ) 1 / 6 [ ] tv ( s ) Dermer, astro-ph/0402438 Baring 2006 Blast Wave Physics with Leptons Electrons • • • Acceleration by Fermi Processes Power in electrons and magnetic field determined by e and B parameters Radiation and cooling by synchrotron and Compton Processes External Medium G Unshocked shell Cloud Forward Shock Reverse Shock G0 Structured jet * GRB source Colliding Shells Captured particle Shocked shell GeV/TeV Component from Leptonic Processes Observed properties sensitive to initial Lorentz factor G0 of outflow (or baryon loading) Dominant SSC component in some cases Dermer, Chiang, and Böttcher (2000) Blast Wave Physics with Leptons and Hadrons Protons • Acceleration by Fermi processes • Energy content in protons determined by e, B parameters: p =1- e - B • Radiative cooling by 1. Proton synchrotron 2. Photopair production 3. Photopion production • Escape from blast wave shell p B p g p g p e ep g N Photopion Production 1. 2. Resonance Production D+(1232), N+(1440),… Direct Production pgn+ , pg , D++ - Mücke et al. 1999 Threshold m 150 MeV pgD0+ 3. 4. Multi-pion production QCD fragmentation models Diffraction Couples photons with r0, w Er r Two-Step Function Approximation for Photopion Cross Section Atoyan and Dermer 2003 ( Er ) 340b, 200 MeV Er 500 MeV , K1 0.2 120b, Er 500 MeV , K2 0.6 Kin ( Er ) ˆ 70b, Er 200 MeV (useful for energyloss rate estimates) Photopion Processes in a GRB Blast Wave Threshold : g p m 400 h / me c 2 Threshold energy E p of protons interacting with photons with energy pk (as measured by outside observer) E p mpc2Gg p f F Fast cooling f pk Describe F spectrum as a broken power law Protons with E > E p interact with photons with < pk, and vice versa a= 1/2 4/3 3 abs c b = (2-p)/2 -0.5 s=2 g0= gc g1= gmin min pk 2 Photopion Energy Loss Rate in a GRB Blast Wave Relate F spectrum to comoving photon density nph(´) for blast-wave geometry (´2nph(´)dL2f/x2G2) Calculate comoving rate t´-1f(Ep) = rf in comoving frame using photopion (f) cross-section approximation Ep rf (0 a 1) Kf Ep All factors can be easily derived from blast-wave physics (in the external shock model) 1- a 1-b Ep Ep Choose Blast-Wave Physics Model Adiabatic blast wave with apparent total isotropic energy release 1054 E54 ergs (cf. Friedman and Bloom 2004) Assume uniform surrounding medium with density 100 n2 cm-3 Relativistic adiabatic blast wave decelerates according to the relation (Böttcher and Dermer 2000) Deceleration length 3 5 7 (Mészáros and Rees 1993) Deceleration timescale 1 s 10 s Why these parameters? (see Dermer, Chiang, and Mitman 2000) (Chiang and Dermer 1999) Energies and Fluxes for Standard Parameters Standard parameter set: z = 1 F flux ~ 10-6 ergs cm-2 s1 Duration ~ 30 s Requires very energetic protons (> 1015 eV) to interact with peak of the synchrotron spectrum -1 Comoving Rates (s ) Characteristic hard-to-soft evolution 10 Standard Parameters 1 r -1 10 10 10 E (10 eV) p 1/t' 10 18 acc ava f -3 -6 E (MeV) -5 r pk esc r -7 f r p,syn -9 1 10 100 1000 Observer time t(s) 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 10 -7 Energies and fluxes Epk ~ 200 keV at start of GRB 10 Photopion Rate vs. Available Time for Standard Parameters Standard parameter set: z = 1 -1 Comoving Rates (s ) Unless the rate is greater than the inverse of the available time, then no significant losses 10 10 Standard Parameters 1 r -1 1/t' 10 10 10 10 18 acc E (10 eV) p ava f -3 -6 E (MeV) -5 r pk esc r -7 f r p,syn -9 1 10 100 1000 Observer time t(s) 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 10 -7 Energies and fluxes Photopion rate increases with time for protons with energy Ep that have photopion interactions with photons with pk Acceleration Rate vs. Available Time for Standard Parameters Standard parameter set: z = 1 Implicitly assumes Type 2 Fermi acceleration, through gyroresonant interactions in blast wave shell Makes very hard proton spectrum n´(g´p) 1/g´p Dermer and Humi 2001 -1 Comoving Rates (s ) Take zacc = 10: no problem to accelerate protons to Ep 10 10 Standard Parameters 1 r 1/t' 10 10 10 10 18 acc -1 E (10 eV) p ava f -3 -6 E (MeV) -5 r pk esc r -7 f r p,syn -9 1 10 100 1000 Observer time t(s) 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 10 -7 Energies and fluxes Assume Fermi acceleration mechanism; acceleration timescale = factor zacc greater than the Larmor timescale t´L = mcg´p/eB Escape Rate vs. Available Time for Standard Parameters Standard parameter set: z = 1 Diffusive escape from blast wave with comoving width <x> = x/(12G). No significant escape for protons with energy Ep until >>103 s -1 Comoving Rates (s ) 10 Standard Parameters 1 r -1 1/t' 10 10 10 10 18 acc E (10 eV) p ava f -3 -5 r -6 E (MeV) pk esc r -7 f r p,syn -9 1 10 100 1000 Observer time t(s) 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 10 -7 Energies and fluxes Calculate escape timescale using Bohm diffusion approximation 10 Proton Synchrotron Loss Rate vs. Available Time Standard parameter set: z = 1 Proton synchrotron energyloss rate: -1 No significant proton sychrotron energy loss for protons with energy Ep 10 Standard Parameters 1 r -1 1/t' 10 10 10 18 acc E (10 eV) p ava f -3 -6 E (MeV) -5 r pk esc r -7 f r p,syn 10 -9 1 10 100 1000 Observer time t(s) 10 3 10 2 10 1 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 10 -7 Energies and fluxes Comoving Rates (s ) 10 Gamma-Ray Bursts as Sources of High-Energy Cosmic Rays Solution to Problem of the Origin of Ultra-High Energy Cosmic Rays (Waxman 1995, Vietri 1995, Dermer 2002) Hypothesis requires that GRBs can accelerate cosmic rays to energies > 1020 eV Injection rate density determined by GRB formation rate (= SFR?) GZK cutoff from photopion processes with CMBR Pair production effects for ankle (Berezinsky and Grigoreva 1988, Berezinsky, Gazizov, and Grigoreva 2005) (Wick, Dermer, and Atoyan 2004) Rates for 1020 eV Protons Standard parameter set: z = 1 -2 10 Calculated at E =10 p 1/t' -3 -1 Comovin Rates (s ) For these parameters, it takes too long to accelerate particles before undergoing photopion losses or escaping. 10 r 10 eV ava r -4 20 esc acc -5 r 10 r -6 10 f p,syn -7 10 1 10 100 1000 Observer time t(s) 10 4 Rates for 1020 eV Protons with Equipartition Parameters Equipartition parameter set with density = 1000 cm-3, z = 1 10 -2 r Calculated at E =10 20 p esc eV -1 Comovin Rates (s ) Within the available time, photopion losses and escape cause a discharge of the proton energy several hundred seconds after GRB 10 -3 r r 10 -4 10 -5 1 1/t' acc ava p,syn r 10 100 Observer time t(s) 1000 f Rates for 1020 eV Protons with Different Parameter Set New parameter set with density = 1000 cm-3, z = 1 Escape from the blast wave also allows internal energy to be rapidly lost (if more diffusive, more escape) 10 -2 Calculated at E =10 20 1/t' -1 Comoving Rates (s ) p 10 ava -3 r acc r 10 -4 r r 10 f esc p,syn -5 1 10 100 Observer time t(s) 1000 eV Blast Wave Evolution with Loss of Hadronic Internal Energy Assume blast wave loses 0, 25, 50, 75, 90, and 95% of its energy at x = 6x1016 cm. Transition to radiative solution Rapid reduction in blast wave Lorentz factor G = (P2 +1)1/2 Rapid decay in emissions from blast wave, limited by curvature relation Highly radiative phase---due to escape of UHECRs from GRB blast wave---proposed as explanation of Swift observations of rapid X-ray declines in GRB light curves Photon and Neutrino Fluence during Prompt Phase Nonthermal Baryon Loading Factor fb = 1 Ftot = 310-4 ergs cm-2 = 100 Requires large baryon load to explain GRB 941017 Hard g-ray emission component from hadronic cascade radiation inside GRB blast wave Second component from outflowing high-energy neutral beam of neutrons, g-rays, and neutrinos pg e ( n, p, ) 0 2g e gg Optical Depth Photon attenuation strongly dependent on and tvar in collapsar model F tot 3 10-4 ergs cm -2 , 50 one sec pulses gg evolves in collapsar model due to evolving Doppler factor and internal radiation field Neutrinos from GRBs in the Collapsar Model requires Large Baryon-Loading Nonthermal Baryon Loading Factor fb = 20 (~2/yr) Dermer & Atoyan 2003 Rapidly Declining X-ray Emission Observed with Swift F - Zhang et al. 2006 Rising phase of light curve shorter than declining phase in colliding shell emission Difficult for superposition of colliding-shell emissions to explain Swift observations of rapid X-ray decay Rapid X-ray Decays in Short Hard Gamma-Ray Bursts GRB 050724 Barthelmy et al. (2005) Loss of internal energy through ultra-high energy particle escape: UHECRs from SGRBs? High-energy g-rays expected from SGRBs from leptonic and, possibly, hadronic components Implications and Predictions • Photopion production Decay lifetime 900 gn seconds Cascade radiation, including proton synchrotron radiation, forms a new g-ray emission component: Explanation of GRB 940217, GRB 941017,… Escaping neutrons and g-rays form hyper-relativistic electrons; transient gray/X-ray synchrotron halos, as in blazars (Coppi, Aharonian & Völk 1994) • Unidentified g-ray Flashes: Proton synchrotron radiation – Discover with GLAST or Milagro – Need rapid alert from GLAST to TeV telescopes 2. Nonthermal Particles and Radiation Produced by Cluster Merger Shocks Thermal bremsstrahlung X-ray Emission of galaxy clusters traces gravitational well Rich clusters (thousands of Galaxies; ~1015 Msun; kT ~ 5-10 keV, LX ~ 1043 1045 ergs s-1) Velocity dispersions ~500-1000 km s-1 Poor clusters (hundreds of Galaxies; ~1014 Msun; kT ~ 1-5 keV, LX ~ 1041 1043 ergs s-1 ) Velocity dispersions ~250-500 km s-1 ~5-10% of total mass of cluster; Orbital motion dominated by distribution of dark matter Which clusters are GLAST/TeV-bright? Structure Formation • Density fluctuations cause region to collapse. – Magnitude of the density fluctuation determines the formation time – Larger structures form by accreting smaller clumps--hierarchical merging – Lumpy, continuous accretion Cluster Merger • Simulation of merging clusters of galaxies Shocks in Merging Clusters • (0, R, ) (mass, curvature, and dark energy)= (0.3, 0.0, 0.7) – Redshift of cluster: – Cosmic Microwave Background (CMBR) dependence • UCMBR(z) = UCMBR(z=0) (1 + z)4 • Rich clusters form by accreting poor clusters • Shocks in Merging Clusters Particle Injection • Power law distribution with exponential cutoff Q ( E , t ) Q ( pc) exp - E - 0 e, p e, p Emax (t ) – Occurs only if M 1.0 – Occurs only during lifetime of shock • Normalization Emax Emin 1 e Ee, pQe, p E , t dE e, p nIC M He m p vs2 As vs 2 – Where e,p is an efficiency factor, and is set to 5%. – Typical values are Etot1063-64 ergs Particle and Photon Energy Spectra: Coma Cluster Fit to Data for the Coma Cluster Galaxy Cluster Nonthermal Brightness Nonthermal Emission from Cluster Merger Shocks • Unidentified EGRET sources: Doubtful • Diffuse Extragalactic g-ray Background: Few % contribution Summary Clusters of Galaxies Unidentified EGRET sources: Doubtful Diffuse extragalactic g-ray background: Few % contribution Predictions: Handful (~ 5 – 10) detected with GLAST (Merger vs. accretion shocks) (Merger shock acceleration vs. turbulent acceleration) GRBs Highly radiative phase from UHECR escape in blastwave evolution proposed to explain rapid X-ray declines in Swift GRB light curves Predictions: 1. 2. 3. Hadronic g-ray light consisting of cascading photopion and proton synchrotron radiation varying independently of leptonic synchrotron Strong GeV-TeV radiation and/or ultra-high energy (>1017 eV) neutrinos correlated with rapidly decaying X-ray emission UHECR emissivity following the GRB formation rate history of the universe Back-up Slides Synchrotron and SSC Radiation Strong dependence of GRB emissions on G0 Selection bias to detect GRBs with Epk within waveband of detector Dominant SSC component in some cases Chiang and Dermer (1999) Two-Step Collapse (Short-Delay Supranova) Model 1. 2. 3. 4. 5. 6. Standard SNIb/c (56Ni production) Magnetar Wind Evacuates Poles GRB in collapse of NS to BH Prompt Phase due to External Shocks with Shell/Circumburst Material Standard Energy Reservoir (NS collapse to BH) Delay time ~< Beaming from mechanical/B-field collimation 1 day (GRB 030329) Infall Velocity