Gamma-Ray Bursts : :sts GeV/TeV photon emission and UHECR/UHEν Peter Mészáros Pennsylvania State University
GRB: (via PNS?) short long
GRB paradigm 3 Mészáros
Fireball Model of GRBs Several shocks - - also possible cross-shock IC Internal Shock Collisions betw. diff. parts of the flow External Shock Flow decelerating into the surrounding medium Reverse shock Forward shock n,p decouple Photospheric th. radiation GRB Afterglow X O R 10 11 cm Mészáros
Standard shock γ-ray components : shock Fermi acc. of e - synchrotron and inv.compton E 2 N(E) Or? GeV νf ν Ext.Sh. Sy (reverse) 0pt Sy (forward) TeV γ ν GRB 990123 bright (9 th mag) prompt opt. transient (Akerlof etal 99). 1st 10 min: decay steeper than forw.sh. Interpreted as reverse shock...... But is it? Mészáros
BAT: Energy Range: 15-150kev FoV: 2.0 sr Burst Detection Rate: 100 bursts/yr SWIFT Three instruments Gamma-ray, X-ray and optical/uv Slew time: 20-70 s! >95% of triggers yield XRT det >50% triggers yield UVOT det. XRT: Energy Range: 0.2-10 kev Mission Operations Center: @ PSU (Bristol Res. Park) UVOT: Wavelength Range: 170-650nm Launched Nov 04 Mészáros, L Aqu05
z=0.937 GRB 080319B A prompt naked eye optical GRB Racusin et al, 08 Nature 455:183 γ, opt prompt l.c. appear similar same emission region, e.g. internal shock; but rad. mechanism? Interpret prompt as: i) optical synchrotron ii) 0.1-1 MeV IC (SSC) (and) iii) predict 2nd order IC @ ~100 GeV (there are also differing opinions) Mészáros
080319b O/UV XR GRB 080318B Mészáros Hei08
GRB 080319B WJ Afterglow Prompt NJ Mészáros
080319B X-Ray 2-jet fit FS-NJ FS-WJ Mészáros Hei08
080319B optical 2-jet fit RS-WJ FS-WJ Mészáros Hei08
A different prompt: GRB060218/SN2006aj There may be more to prompt emission than high Γ shocks! An unusually long, smooth burst, T90~2100±100 s Low luminosity, low energy : Eiso~6x10 49 erg z=0.033, 2nd nearest GRB (138 Mpc) GRB/XRF Campana et al. 2006
A prompt X-ray BB component :...? SN Shock breakout (!) kt~0.17kev BB comp. temp. & radius Contribution of a fitted black-body component (20%) to the 0.3-10KeV flux: BB Interpreted as break-out of an anisotropic, semi-relativistic, radiation-mediated shock from Thomson optically thick stellar wind (Campana et al 06, Nature 442:1006; Waxman, Mészáros & Campana, 07, ApJ 667:351)
UHE CRs &, from GRB pγ, pp UHE, If protons present in (baryonic) jet p + Fermi accelerated (as are e - ) p,γ π ± μ ±,ν μ e ±,,ν e,ν μ (Δ-res.: E p E γ ~ 0.3 GeV 2 in jet frame) Eν,br ~ 10 14 ev for MeV γs (int. shock) Eν,br ~ 10 18 ev for 100 ev γs (ext. rev. sh.) : ICECUBE π 0 2γ γγ cascade : GLAST, ACTs.. Test hadronic content of jets (are they pure MHD/e ±, or baryonic?) Also (if dense): p,γ π ± μ ±,ν μ e ±,,ν e,ν μ Test acceleration physics (injection effic., ε e, ε B..) Test scattering length (magnetic inhomog. scale?..or non-fermi?..) Test shock radius: γγ cascade cut-off: E γ ~ GeV (internal shock) ; E γ ~ TeV (ext shock/igm) photon cut-off: diagnostic for int. vs. ext-rev shock
Fermi Also on Fermi : GBM (~BATSE range) ; 12 NaI: 10keV-3 MeV; 2 BGO: 150 kev-30 MeV Launched June 11 2008 LAT: Pair-conv.modules + calorimeter 20 MeV-300 GeV, ΔE/E~10%@1 GeV FoV = 2.5 sr (2xEgret), ang.res. θ~30-5 (10GeV) Sensit. ~2.10-9 ph/cm 2 /s (2 yr; > 50xEgret) GBM: FoV 4π, 10keV-30MeV 2.5 ton, 518 W expect det/loc ~60 GRB/yr; simult. w. Swift : 30/yr
LL GRB : GeV-TeV γs arising from leptonic sy-ic origin 2 sources of hot IC e - : shocks- a: Γ~2, b: Γ~10 a) rel. jet in SS stage b) semirelat. outflow and 2 sources of seed photons: a) synchrotron (SSC) b) SN UV (SN IC), incl. early th. & late RI He, Wang, Yu & Mészáros 09 Mészáros
Hadronic GRB: easier to look for secondary photons from p,γ interactions Asano, Inoue & Mészáros ApJ in press, arxiv:0807.0951 If GRB are UHECR sources, may need εp/εe 10 tends to give identifiable hadronic photon peak Diagnostic for : high εp/εp : high bulk Γ : high εb/εe Mészáros Hei08
A bright LONG burst : GRB 080916c Abdo et al. (the Fermi collaboration), 2009 Science, 323:1688 1) All spectra approximate Band functions : same mechanism? Could be Synchrotron. No obvious cutoff or a softening Γ 100; expect also SSC, but this could be > TeV, not observed Since no statistically significant higher energy component above Band, the latter must have either E TeV or Y~εe/εB 0.1 2) GeV only in 2nd pulse or later, vs. MeV (1st pulse) - Why? Could originate in different region, e.g. a 2nd set of internal shocks, with parameters or physics (possible) Or radiation from one set of shells up-scattered by another set of shells? (but no expected delay between 2nd LAT & GBM) Mészáros
Counts/bin Counts/bin Counts/bin 1500 1000 500 0 400 200 0 300 200 100 + NaI 4 GBM NaI 3 (8 kev-260 kev) 0.0 3.6 7.7 15.8 0 5 10 15 Time since trigger (s) 20 0 20 40 60 80 100 GBM BGO 0 (260 kev-5 MeV) 54.7 Counts/bin 1500 1000 a b c d e 20 0 20 40 60 80 100 LAT (no selection) Counts/bin Counts/bin 500 400 200 0 5 10 15 Time since trigger (s) 300 200 100 0 5 10 15 Time since trigger (s) 100.8 3000 2000 1000 0 1000 500 0 600 400 200 Counts/sec Counts/sec Counts/sec GRB 080916c Abdo, A. and Fermi coll., 09, Sci. 323:1688 Light-curve E 0 0 Counts/bin Counts/bin 5 0 3 2 1 20 0 20 40 60 80 100 LAT (> 100 MeV) 0 5 10 15 Time since trigger (s) 20 0 20 40 60 80 100 LAT (> 1 GeV) 0-20 0 20 40 60 80 100 Time since trigger (s) Counts/bin Counts/bin 10 5 1.5 1 0.5 0 5 10 15 Time since trigger (s) 15 10 5 0 6 4 2 0 Counts/sec Counts/sec Notice : GeV photons lag behind MeV! Mészáros
GRB 080916C Spectrum Band fits (joint GBM/LAT) for all the different time intervals Soft-to-hard, to sort-of-softpeak-but-hardslope afterglow No evidence for 2nd component Mészáros
GRB 080916c (the Fermi collaboration, 2009) 3) GeV only in 2nd pulse or later, vs. MeV (1st pulse) - Why? Hadronic? (the burning question)... natural delay since extra time for cascade to develop - but : expect hard to soft time evolution & distinct sp. component - not seen) Upshot: more analysis needed to test hadronic model and/or constrain variant of leptonic model Future Fermi+Swift+ground observations will tell Mészáros
GRB 090510 Fermi LAT/GBM identified SHORT burst Shows (sim. to long bursts) time LAG between soft 1st pulse and hard 2nd pulse Shows an EXTRA spectral component, besides usual Band component (first clear!) Hadronic? Maybe... Mészáros
GRB 090510 Spectrum: clear 2nd comp (5σ) Abdo, et al. 09 (LAT/GBM coll.) Nature, subm. arxiv/0908.1832 Mészáros
ε!"ε#$%&'()*+, )-. 34 5C 34 5D Hadronic model: 090510 0 1 )0 γ 234 53 <8=>$?:+@> 0 1 )0 γ 234 5A ε 53>B Asano, Guierec, Mészáros, 09 (ApJL, arxiv0909.0306) Secondaries from photomeson cascades (but: need Lp,iso~10 55 erg/s!) 34 5B ε ν & ν 'ε ν (!"#)*+,-. +/% 678*9':;':8 34 5E 34 C 34 D 34 B 34 E 34 F 34 G 34 34 Secondary photons ε$%&/. Secondary neutrinos (not detectable, for this burst) >? 4A 869)!:6/,65# 012345#,67 892345#,67 8)2;23!<73,=)2;)23 >? 4B >? 4C >? >@ >? >A >? >B >? >C >? >D ε ν!"#$% Mészáros
(Granot, Venice09) Mészáros
Mészáros
Fermi LAT/GBM results (10/9/09) Mészáros
UHE neutrinos from GRB p,γ π ± μ ±,ν μ e ±,,ν e,ν μ Need baryon-loaded relativistic outflow Need to accelerate protons (as well as e - ) Need target photons or nuclei with τ 1 (generally within GRB itself or environment) Need Erel,p 10-20 Erel,e Might hope to detect individual GRB if nearby (z 0.15), or else cumul. background 28
1 e - capt p,n 2 UHE ν in GRB Various collapsar GRB ν-sites 1) at collapse, similarly to supernova core collapse, make GW + thermal ν (MeV) 3 pγ, pp 4 5 6 pγ 2) If jet outflow is baryonic, have p,n p,n relative drift, pp/pn collisions inelastic nuclear collisions VHE ν (GeV) 3 Int. shocks while jet is inside star, accel. protons pγ, pp/pn collisions UHE ν (TeV) 4) internal shocks below jet photosphere, accel. protons pγ, pp/pn collisions UHE ν (TeV) 5) Internal shocks outside star accel. protons pγ collisions UHE ν (100 TeV) 6) External rev. shock: pγ EeV ν (10 18 ev)
Hadronic GRB Fireballs: Thermal p,n decoupling VHE ν, γ Bahcall & Meszaros 2000 Radiation pressure acts on e -, with p + coming along (charge neutrality) The n scatter inelastically with p + The p,n initially expand together, while tpn <texp (p,n inelastic) When tpn ~texp p,n decouple At same time, vrel 0.5c p,n becomes inelastic π + Decoupling important when Γ 400, resulting in Γp >Γn Decay ν, of Eν 30-40 GeV Motivation for DEEP-CORE!
While jet is inside progenitor: Meszaros & Waxman 01 Mészáros pan05
GRB 030329: precursor (& pre-sn shell?) with ICECUBE Burst of Lγ~10 51 erg/s, E SN ~10 52.5 erg, @ z~0.17, θ~68 o Flux of n Razzaque, Mészáros, Waxman 03 PRD 69, 23001 Mészáros pan05
Internal shock ν s, contemp. with γ s Detailed νµ diffuse flux incl. cooling, using GEANT4 sim., integrate up to z=7, Up/Uγ=10 (left) ; z=20, Up/Uγ=100 (right) Asano 05, ApJ 623:967; Murase & Nagataki 06, PRD 73:3002 33
GRB Photospheric Neutrinos GRB relativistic outflows have a Thomson scattering τt~1 photosphere, below which photons are quasi-thermal Shocks and dissipation can occur below photosphere. Acceleration of protons occurs, followed by pp and pγ interactions neutrinos Gas and photon target density higher than in shocks further out. Characteristics resemble precursor neutrino bursts, but contemporan. with prompt gamma-rays Wang, Dai 0807.0290 Murase 0807.0919 34
A different magnetar signature : Magnetar birth ν-alert? Murase, Mészáros & Zhang, PRD 09 ; arxiv: 0904.2509 Magnetars (B~10 14-10 15 G) may result from turbulent dynamo when born with fast (ms) rotation A fraction 0.1 of CC SNe may result in magnetars In PNS wind, wake-field acceleration can lead to UHECR energies E(t) 10 20 ev Z η-1 μ33-1 t4-1 Surrounding ejecta provides cold proton targets for pp π ± ν ν-fluence during time tint first increases (strong initial π/μ cooling), then decreases (with the proton flux) Mészáros
Magnetar birth ν-alert Murase, Mészáros & Zhang 09 Magnetar fluence @ D=5 Mpc Light curve - Can signal birth of magnetar - Test UHECR acc. in magnetar -BUT: Not an explanation for Auger, because a) UHECR flux not sufficient, and b) UHECR spectrum not like Auger obs. Diffuse flux Mészáros
EHE ν s Neutrino fluxes; Asano et al, 09, arxiv:0908.0392 JEM-EUSO sens.: M. Teshima, MPI Crucial parameter for neutrino (and CR) flux is Up/Ee. Note that ν s from pion decay are good targets too (not just muon decay) For typical values Up/Ee ~ 30 needed to make GRB interesting UHECR sources, the neutrino flux might be detectable from individual GRB sources at z~0.1 with 37 JEM- EUSO (K. Asano et al, 2008, in prep.)
AUGER result: UHECR spatial correlations with AGN/LSS Science Nov 2007 Dashed line: supergalactic equator Circles (proton): Events E>4.5x10 19 ev Crosses: Veron-Cety catalog AGNs
Auger spatial correlation Found 3σ corr. with V.C. AGNs within 3.5 deg inside 75 Mpc, for 28 events E>4.5x10 19 ev The above correlation suggest protons Science, 07 But cannot say positively it is AGNs - could be correl. with underlying LSS Kashti-Waxman confirm correl. with LSS at >98% confidence level, via two-pt corr., ang. power spectr. and predicted-observed coincid. If heavy mix: many more gals. inside each event s larger angular spread. But: AGN significance now (09) weakened to 1.7 σ 39
CR Flux & spectrum - GRB [Waxman 95] Mészáros grb-glast06
GZK CR Sources Sources: GRB ; AGN... #? Rate: R GRB (z=0)~ 0.5 Gpc -3 yr -1 ~ 0.5 10-3 (D/100 Mpc) -3 yr -1 But, arrival time dispersion: t dis ~ 10 7 yr (B/10-8 G) 2 (λ B /1 Mpc) (D/100MPC) 2 (E p /10 20 ev) -2 N GRB (E>E p, D<D GZK ) ~ R. t disp ~ 10 4 B 2-8 λ B,0 D 2 100 E 2 p20 GZK event rate: ~ 1 /Km 2 /100 yr [Waxman 95, 2005] Mészáros grb-glast06
UHECR data vs. GRB model Waxman 06
What about Eν 10 19 ev? 2 CR models same GZK CR fit from GZK CRs to GZK νs But lead to GZK ν flux Can infer GZK CR injection spectrum and/or source cosm. luminosity evolution via their GZK νs. Seckel & Stanev astroph/050244 43
GRB GZK cosmogenic neutrinos Yuksel & Kistler 07 PRD 75:083004 If GRB make the GZK UHECR, then: ν flux dep. on GRB rate vs. z (from z>> RGZK ) 44 Yuksel et al, 2007
Potential of Cosmogenic νs for CR Composition If CRs have large fraction of heavies, depending on source distance, photodissociation opt. depth could be <1 only some of them break up into p,n Implies smaller fraction contributes to π + and cosmogenic ν production (Anchordoqui et al 06) Cosmogenic ν flux vs. CR flux may help resolve discrepancy between Auger Xmax data and apparent correlation with AGN suggesting protons 45
Conclusions Much new information about GRB in the VHE range from Fermi They are likely sources of UHECR and UHENU, but still unknown Will learn much about best UHECR/UHENU candidates (GRB, AGN, MGR?) from GeV and TeV photon observations with good statistics TeV gamma obs. Fermi: (a) Second spectral component found; (b) HE emission SGRB ~ LGRB, (c) MQG > MPlanck for n=1, need n 2 Will constrain particle acceleration / shock parameters, compactness of emission region (dimension, mag.field,.) UHECR : chemical composition, angular correl.: sources? UHE ν will allow test of proton content of jets, proton injection fraction, test shock acceleration physics, magn. field If UHE ν NOT detected in GRB jets are Poynting dominated! Probe ν interactions at ~ TeV CM energies Constraints on stellar birth & death rates @ high-z, first structures? Cosmogenic nus: probe CR origins, sources
Back-up slides
Origin of 10 19-10 21 ev UHECR: may be GRB - but what about 10 16-10 19 ev? Radio, x-ray & gamma-ray observations of SN1998bw/GRB980425 sub-energetic GRB GRB980425: E~1e48 erg (d=38 Mpc) Radio afterglow modeling: E>1e49 erg, \Gamma~1-2 X-ray afterglow: E~5e49 erg, \beta=0.8 Mildly relativistic ejecta component E_SN=3-5e52 erg V=0.1c S N SN shock acceleration in the Envelope? Tan et al. 01 Woosley et al. 99 Other SN/GRB w. semi-relativistic ejecta: SN2003lw/GRB031203 SN2006aj/GRB060218
The maximum energy of accelerated particles 1) Type Ib/c hypernovae expanding into the stellar wind of Wolf-Rayet star 2) equipartition magnetic field B, both upstream and downstream Maximum energy: Hillas 84, Bell & Lucek 2001 Protons can be accelerated to ~10 19 ev Heavy nuclei can be accelerated to ~Z*10 19 ev
Flux level--- energetics Kinetic energy generation rate: Compare w. normal GRBs The required rate : Rate (z=0) kinetice nergy Hypernova (v=0.1c) ~500 ~1 Normal Ib/c SN rate: Normal GRBs 3-5e52 erg 1e53-1e54erg sub-energetic GRB rate: Soderberg et al. 06
Energy distribution with velocity Data from Soderberg et al. 06 Normal SN Very steep distribution -> negligible contribution to high-energy CRs Berezhko & Volk 04 Semi-relativistic hypernova: high velocity ejecta with significant energy is essential Wang, Razzaque, Meszaros, Dai 07 CR spectrum:
Transition from GCRs to EGCRs
Semi-relat. ( slow ) jets in core-collapse SN? Maybe all core coll. (II or Ib/c) SN resemble (watered-down) GRB? Evidence for asymmetric expansion of c.c. (Ib/c) SNR: - asymmetric remnants - optical polarization - jets may help eject envelope slow jets Γ~ few? Mészáros TeV05
Core collapse SN : slow jets? Spectrum and diffuse flux Razzaque, Mészáros, Waxman, 2004, PRL 93, 181101 Ando & Beacom, 2005, PRL 95, 1103 Maybe all core coll. (or Ib/c) SN resemble (watered-down) GRB? Evidence for asymmetric expansion of c.c. (Ib/c) SNR: slow jets Γ~ few? If so, accel protons while jet inside star, pγ π,μ ν (TeV) Diffuse flux: negligible, but individual SN in nearby (2-3 Mpc) gals, e.g. M82, NGC253, detectable (if have slow jets), at a rate ~ 1 SN/5 yr, fluence ~2 up-muons/sn (hypernova: 1/50 yr, 20 up-μ), negligible background, in km 3 detectors - ICECUBE
LIV limits GRB 080916C Fermi collaboration (Abdo et al), 2009, Sci.. 1st and 2nd order (n=1,2) energy dependent pulse time dispersion in effective field theory formulation of LIV effects, where leading order deviation is E 2 - p 2 - m 2 ± E 2 (E/EQG) n Conservative lower limit on EQG, taking Eh/t (Eh/t 1/2 ) with t=pulse time since trigger These are (almost) the most stringent limits to-date via dispersion Mészáros