Ultra-High Energy n from Gamma-Ray Bursts

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1 Ultra-High Energy n from Gamma-Ray Bursts Peter Mészáros Pennsylvania State University

2 First Detection of GRB Vela 4a (US DoD) monitored nuclear (& cosmic!) explosions First GRB det: 1967 (pub: Klebesadel, Strong, Olson 1973 ApJ 182, L85) Vela 5a,b/6a,b det 73 GRB in Prognoz 2 (USSR) det GRB, and Konus/Venera det. 85 GRB (Mazets, Aptekhar& Golenetskii 1981)

3 Compton Gamma Ray Observatory (CGRO): g-ray detectors: -BATSE: 20keV-1MeV -OSSE: MeV -Comptel: MeV -EGRET: 30MeV-20GeV CGRO MAIN RESULTS: BATSE all-sky survey: 1) GRB isotropic distrib., implying cosmol. distance 2) Long (>2 s) & short (<2 s) 3) Non-thermal g- spectra

4 GRB Spectra BATSE EGRET Spectra are non-thermal (broken PL) E pk ~ 0.3 MeV, most energy above it Flux extends >10 GeV in some GRB GRB Durations: Range: t g ~ s short 2 s long bimodal (short/long)

5 BeppoSAX: g-ray wide-angle det. + XR NFI + UVO tel 1 st afterglow det! ~ 40 GRB XR/O/R afterglows det., and Æ Precise loc n host galaxy redshift dist. calibr. flux, energy ò GRB X-ray fading afterglow

6 GRB: basic numbers Distance: 0.35 d z d4.5 D ~ cm Fluence: F = flux. dt ~ erg/cm 2 ~ 1 ph/cm 2 Energy output: (Ω/4π) D F -5 erg jet: Ω ~ E γ,tot ~ erg E ~ L γ,tot Θ x 1010 year ~ L gal x 1 year Rate(GRB) ~ 1/day 10-6 (Ω/2π) -1 /yr/gal (whereas Rate[SN] ~ 10 7 /yr ~ 1/s at z d1)

7 Generic GRB model: Hyperaccreting BHs ôshort Note: should Also produce Neutrinos, Gravity waves ôlong

8 Explosion FIREBALL E γ t Ω -2 D F -5 erg R 0 ~ c t 0 ~ 10 7 t -3 cm Huge energy in very small volume τ γγ ~ (E γ /R 3 0m e c 2 )σ T R 0 >> 1 Fireball: e ±,γ,p relativistic gas L γ ~E γ /t 0 >> L Edd expanding (v~c) fireball (Cavallo & Rees, 1978 MN 183:359) Observe E γ > 10 GeV but γγ e ±, degrade 10 GeV 0.5 MeV? Eγ Et >2(m e c 2 ) 2 /(1-cosΘ)~4(m e c 2 ) 2 /Θ 2 Ultrarelativistic flow Γ t Θ -1 ~ 10 2 (Fenimore etal 93; Baring & Harding 94)

9 BH + accr. Torus Jet Collapsar or merger BH+accr.torus Nuclear density hot torus nn e ± Hot infall conv. Dynamo B~10 15 G, twisted (thread BH?) Alfvénic or e ± pγ jet (Note: magnetar might do similar)

10 Jet emergence from star Zhang, et al astro-ph/ Num.simulations: (Aloy et al 00 ; Zhang, Woosley, McFadyen 02) So far: 2D, SR; jet first v h dc, then v h c, in agreem t w. analytical calc s KH instab: variable power output, G Prelim. (num.) concl.: jets emerge only from stars of R ø d10 11 cm; but larger stars not calculated num ly; analyt. est. indicate larger radii may be possible (Meszaros, Rees 02, ApJ 556, L37) G t 150, OK

11 Shocks in Fireball Outflow external shock Internal shocks Shocks expected in any unsteady supersonic outflow (esp. in a nonvacuum environment) Internal shocks: fast shells catch up slower shells (unsteady flow) External Shock: flow slows down as plows into external medium NOTE: ext. termination shock & internal shocks can be expected also while jet is still inside star

12 Shock Acceleration Non-th. g-sp. Strong shocks accelerate charged particles (e ±,p + ) relativistic power law Post-shock turbulent dynamo mag.fields (e ±,B) e ± synchrotron, (g, e ± ) Inv.Compton g broken power-law (non-thermal) g-spectra from power-law e ± [Other possibilities: - magn.reconnect. lin.accel. (Drenkhahn); - wake-field accel. lin.accel. (Chen et al) ] N(g) N(E g ) E g 2 G p+ <G(m p /m e ) e ± -q : slope g e± IC e ± Sy (q-1)/2 E g

13 GeV-TeV photons from GRB Baring 1999 Internal shocks: gg e, t gg E g t G GeV pair cutoff in spectr ï get info about r sh (compactness,t gg ) In ext.shock, t gg 1 on GRB target g; test if shock is int. or ext; test bulk Lorentz factor, shock accel efficiency, magnetic field in shock (max. e energy? size of accel region)

14 gg Opacity of the Universe g Coppi & Aharonian 97 In ext.shock, t gg 1 for >TeV on GRB target g, but In Universe, t gg 1 for >TeV on IR bkg g (Dd100Mpc) test IR bkg spectral density, constrain early star formation rate & z-distr of SFR, LSS, cosmology

15 GeV-TeV g & GW Facilities Cherenkov Telescopes TeV Water Air HESS, VERITAS,.. MILAGRO GLAST Pair conv 20 MeV- 300 GeV ô LIGO Laser interf Grav wave Detector

16 CR s & n s : sub-tev to ZeV Universe opaque to g e g t10 12 ev due to gg e ± on IR backg. g U. also opaque to p at e p t10 20 ev due to pg p + + on CMB all p of e p d10 19 ev lose direction info (B gal ) n is only UHE witness from high z pointing back to its source! Æ (Halzen, Hooper 02)

17 Thermal Proton-Neutron Effects in GRB Fireball p n p n r dec p-n in f ball move together while t pn > t exp (rad. press. acts on p, elastic scattering couples p,n) p-n decouple when t pn tt exp (also t pn ~1, v rel Øc) s pn Ø inelastic; occurs for GtG p ~400 (Derishev etal 99; Bahcall,Meszaros 00; Fuller etal 00) Inelastic pnøp ± Øm ±,n m Øe ±,n e,n m e nm ~5-10 GeV ICECUBE: z~1, R n ~7/yr from all GRB, in coinc.w. g -rays (but only if larger PMT density) GLAST: p 0 Ø2g, e g ~10 GeV, z~0.1 (Bahcall & Meszaros 2000 PRL 85:1362)

18 Relativistic Proton Effects in GRB J E 2.61 [ev 1.61 /m 2 sr s] N(E p ) GRB flux GRB flux + Fly s Eye consequences? g, n,.. E p Galactic (heavy) component AGASA Fly s Eye Yakutsk UHE CR spectrum E [ev] (Waxman, Neutrino 2000, hep-ph/ )æ Shocks: internal & ext. rev. shocks: mildy relativistic p-spectrum N(E)µE -2 Can reach E p d10 20 ev (& contr. to diff. CR flux: Waxman 95; Vietri 95) Other obs. effects? 1) p-synchrotron g ; but narrow param.space (Totani 98, Zhang & Mészáros 01) 2) photo-hadronic g s (Böttcher & Dermer 98; Fragile etal 02) 3) photo-hadronic n s (Waxman & Bahcall 97)

19 UHE n s from pg collisions Int. shocks: E p >10 16 ev, coll. with ~1 MeV g-rays, dn g /de E -b, b~1,2 pg π ± µ ±,n µ e ±,,n e,n µ E n ~ 5x10 14 ev G 300 (E g /1MeV) -1, ( -res.) E n 2 Φn 10-9 (En/En b ) GeV/cm 2 s sr (Waxman, Bahcall 97; Rachen, Meszaros 98) External shock: E p >10 19 ev, coll. with ~10 ev g s, E n ~ ev, (Waxman,Bahcall 00, Vietri 98) E 2 nφ n (E n /10 17 ev) b GeV/cm 2 s sr detect w. ICECUBE (& test shock acc) pg π 0 2g, Eg ~0.1-1 GeV GLAST

20 UHE n Fluxes & Limits MPR99 P97 HZ97 M95B E 2 ν Φ ν [GeV/cm2 s sr] GRB (burst) WB Limit GRB (afterglow) E ν [GeV] E 2 Φ n power/decade UHE n from GRB ( burst ) int.shocks, from GRB ( afterglow ) ext. reverse shocks, and from various AGN jet models; also Waxman-Bahcall WB 98 and MPR 99 CR limits Range of possible neutrino fluxes associated with the maximum energy CRs. Transparent : source From which CRs escape after one interaction; obscured : where CRs are trapped, only n s escape. (from Halzen & Hooper 02)

21 TeV n from bursting & choked GRB Star edge Mészáros, Waxman 01 PRL 87: Collapsar : jet has termination shock and internal shocks, also while inside the star Int. shocks accel. protons to E p >10 5 GeV, which collide with thermal X-rays in jet cavity Ent2(2/1+z) TeV F n 10-5 E 53 /D 282 erg/cm 2 N µ ~ 0.2/km 2 (avg., R~10 5 /yr) ~ 10 /km 2 (rare, R~ 3 /yr) n-precursor in g-bright GRB; n- burst in g-dark (choked)grb new unseen sources! e.g. first gen. (pop. III) stars?

22 Diffuse UHE n from pop.iii collapse At z~ 6-30(?): pop.iii ø, M * ~ M Ÿ, core coll. M BH ~ M Ÿ E iso ~ (?) erg Buried jets pg n m, n-bursts, AMANDA/ICECUBE Escaping jets? pg n m Schneider, Guetta, Ferrara aph/ n,g-bursts, ICECUBE, Swift e n ~1-50TeV, e g ~0.1-1MeV Detect highest -z øform n, get primordial IMF,

23 Prediction model-dependence & Detectability of GRB n E n ~100 TeV are least model dependent (use observed MeV g & same shocks as accelerate e ± ) E n ~1 TeV : more model dependent, (also assume collapsar model, and R ø t cm ) E n ~ ev : need assume reverse shock prompt opt flash is ubiquituous (?) E n ~ 5 GeV: likely, but need special instr t

24 Other Implications of GRB n Special relativity: simultaneity of arrival of n,g tested to Dt d 1 s (10-3 s in short bursts) Time delay due to n i mass: Dt (n i )~10-12 (D/100Mpc)(E ni /100TeV) -2 (m ni /ev) 2 s (whereas for SN 1987a Dt (n i )~ 10-8 s ) Vacuum oscillations: at source exp. Nn m ~ 2Nn e, at observer exp. º ratios, and upgoing t appear. sensitive to Dm 2 t10-16 (E n /100TeV)(100Mpc/D) ev 2 (for m n t0.1 ev due to finite pion life mixing is caused by decoherence rather than oscillation)

25 Summary GRB studied from radio to t GeV (so far) Working model (relat. fireball + shocks) works well (so far): will it continue to? Progress being made on central engine, progenitor Significant potential as cosmological tool TeV-EeV neutrino signals: new window - absorption & deflection-free UHE astrophys. probe - probe fund. interactions & E cm t PeV More surprises expected!