Gamma-Ray bursts. Neutrinos. Peter Mészáros. Pennsylvania State University. Mészáros, NOW 04

Transcription

1 Gamma-Ray bursts & Neutrinos Peter Mészáros Pennsylvania State University

2 GRB Spatial & Temporal Distrib. Cosmological (isotropic) distribut. Out to z t 4.5 (20?) ~ z d few ~ 1/3 short (t g <2s) NS mergers/mag? ~ 2/3 long (t g >2s) massive coll/sn

3 Lightcurves: The GRB Zoo Varying durations t g ~ s Varying light-curve envelopes, but, systematics: Variability timescale t var 10-3 s implies source size r ct g ~100 km Time distribution is bimodal (short,long) This suggests that there are at least two distinct source mechanisms or source types

4 GRB g spectra (0.1-3 MeV, BATSE): broken power law ï non-thermal mechanism

5 GRB: (current paradigm) Short (t g d 2 s) (Observed, but origin unconfirmed) Long (t g t 2 s) (Observed, and origin confirmed) (+ some successful supernovae)

6 An explosive ancestry: some SN (cc, Ib/c,..) long GRB other SN NS (+NS?) short GRB? An explosion leads to another explosion (but with very different delays: minutes vs Myrs) And the GRB explosions announce themselves via : Electromagnetic (EM) flares : g, X, UV/O, sub-mm, R Ultra-high energy g-rays, MeV EeV neutrinos?) Ultra-high energy cosmic rays (GZK)?, Gravitational Waves (GW) (KHz, mhz, mhz )

7 M remn. vs. (from Heger, et al 03) M øms Non-rotating single ms ø Mass-loss simplified Metallicity dependence? Core rotation, binary evol n? Etc WHAT is the stellar mass distribution (at high z)??

8 Neutrinos from GRB Various mechanisms & energy ranges: E n ~10-30 MeV : core collapse thermal n - However: even though ~as n-luminous as normal SN, expect only 10-4 GRB-SN/yr/gal (vs normal-sn/yr/gal) E n GeV : np decouple in baryonic fireball E n TeV : pg in internal shocks in jet (both inside & outside star) E n EeV : pg in external reverse shock (afterglow)

9 GRB: basic numbers Distance: 0.1 d z d4.5 D ~ cm Fluence: F = flux. dt ~ erg/cm 2 ~ 1 phot/cm 2 (g-rays ) Energy output: (Ω/4π) D F -5 erg jet: Ω ~ rad E γ,tot ~ erg E ~ L γ,tot Θ x 1010 year ~ L gal x 1 year Rate(GRB) ~ 10-6 (2π/ Ω) /yr/gal 1/day (zd3) whereas Rate [SN] ~ 1O -2 /yr/gal, or 10 7 /yr ~ 1/s (z d3)

10 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)

11 Paradigm: BH + accr. Torus Jet Both collapsar or merger BH+accr.torus fireball Massive rot. ø: sideways pressure confines/channel outflow fireball Jet Nuclear density hot torus can have nn e ± jet Hot infall convective dynamo B~10 15 G, twisted (thread BH?) Alfvénic or e ± pγ jet (Note: magnetar might do similar)

12 Are ultra-relativistic jets possible? 3-D hydro simul n (Aloy et al 00 ; Zhang, Woosley, McFadyen 02; Zhang, Woosley03) So far:sr w/o MHD; jet v h c as in analyt. calc OK - G up to 150 OK - KH instab: variable outp., var G OK Prelim (num) concl: jets emerge only from R ø d10 11 cm; (but larger stars not yet done num ly); However: analytical calc. indicates jets may emerge from larger, e.g. BSG stars, (Meszaros, Rees 02, ApJ 55L37) W. Zhang & Woosley 03 `

13 MHD Jet simulation MHD, w/o SR (ZEUS-2D axisym) of collapsar model pre- SN 25 M Ÿ star w. init. rotat and weak B r, realistic EOS, n- coolg, He photodis, resist. htg MHD effects alone can launch, accel & sustain strong Poynting dominated jet But: Newtonian, 0.3c (Proga, McFadyen, Armitage, Begelman astro-ph/ ) AGN: MHD jets also a strong possibility, but remains unsettled.

14 Relativistic Outflows Energy-impulse tensor : T ik = w u i u k + p g ik, u i : 4-velocity, g ik = metric, g 11 =g 22 =g 33 =-g 00 =1, others 0; ultra-rel. enthalpy: w = 4p µ n 4/3, w, p, n : in comoving-frame 1-D motion : u i =(γ,u,0,0), where u = G (v/c), v = 3-velocity, A= outflow channel cross section : Impulse flux Q=(w u 2 +p) A energy flux L= wu G c A particle number flux J= n u A Isentropic : L, J constant î w G /n = constant (relativistic Bernoulli equation); for ultra-rel. equ. of state p µ n 4/3, and cross section A µ r 2 î n µ 1 / r 2 G comoving density drops î Gµ r bulk Lorentz factor initially grows with r.

15 Dynamics of expansion Bulk Lorentz factor initially grows with r (internal energy T a r -1 gets converted into Γ µ r energy of motion ) But eventually acceleration saturates when gas becomes nonrelativistic in its restframe : Γ~ h =L/(dM/dt) = constant coast at constant speed How long can it coast at constant speed? not too long: shocks (or other form of dissipation) slow-down randomization of energy radiation

16 Jet (outside the star) shocks external shock ò 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 reverse forward NOTE: external and internal shocks might be expected also while jet is inside star, as well as after it is outside the star. If inside: gs do not escape (but n can) if outside: gs do escape (and n too)

17 Shock formation Collisionless shocks (gas too rare) Internal shock waves: where? If two gas shells ejected with G=G 1 -G 2 ~G, starting at time intervals t ~t v,, they collide at r is, r is ~2 c t G 2 ~2 c t v G 2 ~6.1O 11 t -3 G 22 cm (internal shock) External shock : merged ejected shells coast out to r es, where they have swept up enough enough external matter to slow down, E=(4p/3)r es 3 n ext m p c 2 G 2, r es ~ (3E/4pn ext m p c 2 ) 1/3 G -2/3 ~ 3.1O 16 (E 51 /n O ) 1/3 G 2-2/3 cm (external shock)

18 Shock Photon Spectrum E 2 N E Sy IC Non-thermal power law spectrum, both in int. and ext. shocks, due to Synchrotron, peak at ~200 kev (or ~ ev?) F E R t t O E X, g Inv. Compton, peak ~ GeV (or ~200 kev? Sy peak location, ratio Sy/IC dep. on B sh, g e,m Peak softens with time E Ratio Sy/IC decr w. time

19 Non-thermal gs: Internal & External Shocks in optically thin medium outside progenitor: SHORT & LONG-TERM BEHAVIOR Shocks solve radiative inefficiency problem (reconvert bulk kin. en. into random en. radiation) Γ r c r i r e R ø Int Ext r Lorentz factor Γ first grows Γ r, then saturates, Γ constant, until Outside the star, after jet is opt. thin: Internal shocks: r i ~10 12 cm γ-rays (burst, t~sec) Externals shocks start at r e ~1016 cm, progressively weaken as it decelerates PREDICTION : External forward shock spectrum softens in time: X-ray, optical, radio long fading afterglow! (t ~ min, hr, day, month) External reverse shock (less relativistic): Optical quick fading ( t ~ mins) (Mészáros & Rees 1997 ApJ 476,232)

20 GRB : BeppoSAX Discovery of an afterglow Feb 28 March 3 F x ~ erg.cm 2 /kev/s, decr. by 1/20 X-ray location:2-3 arcmin raster optical (arcsec) & radio location Can identify host galaxy, redshift located at cosmological dist. NEW ERA! (Costa et al 1997, Nature 387:783)

21 Evidence for GRB afterglow blast wave model: power law time decay & spectra GRB as blast wave: Wijers, Rees & Mészárosl 97 MNRAS 288:L51 fit to Mészáros, Rees 97 ApJ 476:232 model Simplest model predictions work surprisingly well remains quite robust after > 60 afterglow dets. basics: adiabatic forward shock synchrotron rad n from shockaccel. non-thermal e - F(n,t) n -b t -a, a = (3/2) b Parameters E 0, e e, e B, n ext, photon index b=(p-1)/2 p/2 Long-term (months) optical afterglow easier follow-up redshifts : confirm and det. cosmological distances, distrib.

22 In external shock, expect both a Forward & Reverse Shock Synchrotron and IC components for both forward and reverse shocks Forward shock IC (GeV g ) Forward shock synchrotron(x,g) Reverse shock synchrotron (O) Meszaros, Rees, Papathanassiou 94, ApJ 432, 578

23 Evidence for Reverse Shocks: Prompt Opt. Flashes GRB bright (9 th mag) prompt opt. transient (Akerlof etal 99) 1st 10 min: decay steeper than forw. shock Interpreted as reverse external shock (predicted : Mészáros&Rees 97) 99-02: Great Desert: Lack of flashes, upper limits m v ~12-15 nf n Akerlof etal 99 Kulkarni et al 99 Sy (forw) Sy (rev) 0 X,g n but: New generation robotic tels: ROTSE III, Super-LOTIS, RAPTOR, KAIT, TAROT, NEAT, Faulkes, REM; etc new prompt optical flashes: GRB , : similar to GRB new semi- prompt flashes, ( ROTSE IIIa (AU), ROTSE IIIb (TX) ): GRB , : π from GRB ! t >211, 50 s resp, see forw. shock only? steep rise (ascribed to dusty stell. wind) m R ~ 17 at t~ 30 min, then PL decay (Rykoff etal astro-ph/ )

24 Prompt Opt. Flashes : ROTSE Robotic Optical Transient Search Experiment (Akerlof, etal, 99, Nat 398, 400) Cannon f/1.8 35mm cams coupled to CCD fast slew (3s anywhere) Detected 1 st bright (m v =9) prompt (15s after trigger) optical flash in GRB Succesor experiments: ROTSE III, Super-LOTIS, RAPTOR, KAIT, TAROT, NEAT, Faulkes,REM, etc.

25 Evidence for jets: Light curve breaks Monochromatic break in light curve time power law expect G t -3/8, as long as q light cone ~G -1 < q jet, (spherical approx is valid) see jet edge at G ~q jet -1 Before edge, F n (r/g) 2.I n After edge, F n (rq jet ) 2.I n, F n steeper by G 2 t -3/4 After edge, also side exp. further steepen F n t -p

26 Evidence for Collapsar & SN? and: does one imply the other? Evidence for massive stellar progenitor: long GRB are all in (massive) star-forming regions, evidence for metals, dust, etc. Core collapse of star w. Mt30 M Ÿ : expect BH + disk (if fast rot.core) jet (MHD? baryonic? high G, + SNR envelope eject (?) 3D hydro simulations (Newtonian SR) show baryonic jet w. high G can form & escape SN shell ejection: not seen numerically yet, even though seen in nature (M 25 M Ÿ stars) but: in GRB, several previous observational suggestions of ejected SNR shell, e.g. late l.c. hump + reddening- and debate) ; and more recently Collapsar & SN (ANIMATION!) Credit: Derek Fox & NASA Ø

27 Strong Evidence for Collapsar & SN : GRB SN 2003dh : Yes! 2 nd Nearest unequivocal cosmological GRB: z=0.17 GRB-SN association: strong Fluence:10-4 erg cm -2, among highest in BATSE, but Dt g ~30s, nearby; E g,iso ~ erg: ~typical, E SN2003dh,iso ~ erg ~ E SN1998bw,iso ( grb980425) v sn,ej ~0.1c ( hypernova ) GRB-SN imultaneous? at most: d 2 days off-set (from opt. lightcurve) ( ï i.e. not a supra-nova ) But: might be 2-stage (<2 day delay) ø- NS-BH collapse? n predictions may test this! (other: GRB031203/SN2003lw, z=0.1055, aph/ )

28 Evidence for magnetized outflow?: g-ray polarization (maybe) RHESSI (solar g-ray obs): 9x300 cm 3 Ge dets. coaxial with Sun, rotation P= MeV see scattering events in 2 or more dets. A scatt,eff ~ 20 cm 2, mod.factor ~0.2. Figure 1 : GRB : Fluence~1.6x10-4 erg/cm 2, Dt obs,pol =5s : 80% ± 20% pol. (!) (Coburn & Boggs, Nat 2003, 423, 415) Figure 2 : if Synchrotron ô(a) strong polarization suggests magnetic field is ordered, provided the line-of-sight is close to the jet axis. ô(b) Or, if line-of-sight near edge of jet light cone, similar deg. of polarizat n possible even for random. mag. fields (can look ordered inside q~1/g <<q jet ) (Waxman, Nature 2003, 423, 388 ) But: controversial: (Rutledge & Fox aph/ ) ; partial rebuttal : (Boggs & Coburn astroph/ )

29 UHE n in GRB 1,2 e - capt p,n 5(6?) possible collapsar n-sites 1) ôat collapse, make GW + thermal ns 2) ô If jet outflow is baryonic, have p,n p,n relative drift, pp/pn collisions inelastic nuclear collisions VHE n (GeV) 3,4 pg, pp 3 ôint. shocks while jet is inside ø can accel. protons pg, pp/pn collisions UHE n (TeV) 4 ôint. shocks outside ø accel. protons pg collisions UHE n (100 TeV) 5) Ext. rev. shock EeV n (10 18 ev) 5,6 pg 6) If supranova shell present outside (SN ocurred >2 days before GRB?) pg, pp of jet protons on shell targets UHE n (> TeV) [..now constrained]

30 Hadronic GRB Fireballs: Thermal p,n decoupling VHE n,g p n p n r dec p,n in f ball move together while t pn > t exp (rad. acts on p, elastic scatt. couples p,n) p,n decouple when t pn tt exp, where t pn ~1, v rel Øc, s pn Ø inelastic; this occurs for GtG p ~400 (Derishev etal 99; Bahcall,Meszaros 00; Fuller etal 00) Inelastic pn Æ p ± Æm ±,n m Æe ±,n e,n m p 0 2g n m : e nm ~5-10 GeV ICECUBE? z~1, R n ~7/yr from all GRB, but only if larger PMT density g-rays: p 0 Ø2g, GLAST, e g ~10 GeV, zd0.1 (Bahcall & Meszaros 2000 PRL 85:1362); Lemoine 2002; Beloborodov, 2002

31 p,g UHE n,g If protons present in (baryonic) jet p + Fermi accelerated (as are e - ) p,g π ± µ ±,n µ e ±,,n e,n µ ( -res.: E p E g ~ 0.3 GeV 2 in jet frame) E n,br ~ ev for MeV gs (int. shock) E n,br ~ ev for 100 ev gs (ext. rev. sh.) ICECUBE p 0 2g gg cascade GLAST, ACTs.. (Waxman-Bahcall 1997;99; Boettcher-Dermer 1998; 00; ) Test hadronic content of jets (are they pure MHD/e, or baryonic?) Test acceleration physics (injection effic., e e, e B..) Test scattering length (magnetic inhomog. scale?..or non-fermi?..) Test shock radius: gg cascade cut-off: e g d GeV (internal shock) ; e g d TeV (ext shock/igm) Different gg cut-off due to π compactness param. (t gg, R sh ) photon cut-off: diagnostic for int. vs. ext-rev shock

32 Available proton energies: CR Protons from GRB J E 2.61 [ev 1.61 /m 2 sr s] GRB flux GRB flux + Fly s Eye Galactic (heavy) component AGASA Fly s Eye Yakutsk E [ev] (Waxman, Neutrino 2000, hep-ph/ ) Internal & extern.(rev) shocks NR Fermi acc. spectrum N(E) E -2 Can reach E~10 20 ev (for x B x e 0.02, G 130) CR energy input at10 20 ev de/dtdv~10 44 zerg/mpc 3 /yr where z~0.5-3 (z-evol.) Entire >10 20 ev CR flux from GRB? yes/no/possibly (Waxman NucPhS 87:345 00; Stecker APPh 14:207 00; Vietri et al 02;..) BUT : for TeV ns, need only 20 TeV protons (pg)

33 UHECR total power in GRB? Previous ( ): E g ~10 51 erg, R(z=0)~30/Gpc 3 /yr, de/dtdv~0.3x10 44 erg/mpc 3 /yr New (>2000): E g ~2.5x10 53 erg (isot.equiv); R (z=0) ~5x10-10 /Mpc 3 /yr, de/dtdv~1.3x10 44 z erg/mpc 3 /yr. (z ~ 3-8 to z~1, evol) Jets: 4p/500 (E g, RÆ, ) E e2 dn e GRB /de e dt ~10 44 z erg/mpc 3 /yr UHECR extragal. obs: de p CR /dt ~ 3x10 44 erg/mpc 3 /yr E p2 dn p CR /de p dt ~0.7x10 44 erg/mpc 3 /yr,, OK. (Waxman, astro-ph/ )

34 GRB: internal & external shocks (outside progenitor star)

35 ns from pg in internal & external shocks in GRB Waxman, Bahcall 97 PRL Shocks accel p + as well as e - p PL -res.: E p E g ~0.3GeV 2 in comoving frame, in lab: E p 3x10 6 Γ 2 2 GeV E n 1.5x10 2 Γ 22 TeV Internal shock pg MeV ~100 TeV ns External shock pg UV ~ EeV n Diffuse flux: det. w. km 3

36 (2) Jet inside star: GRB n,g Precursor E ν Φ ν ε op (GeV cm s sr ) pp (stellar) H Meszaros, Waxman 01 PRL WB Limit 7.5 pγ (head) pp (shocks) pγ (head) 8.5 ICECUBE 9 9 pγ (shocks) 10 Burst 9.5 WR 10 He Afterglow H E ν (GeV) Atmospheric 5 10 bursts/yr Razzaque, Mészáros, Waxman 03 PRD 68, 3OO1) Jet propagating through progenitor, BEFORE emerging from stellar envelope, can have int. shocks which accel. p + pg on unobserved X-rays, p ±, n pp, pn on stellar envelope p ±, n ~ few TeV neutrino precursor If progenitor has H-layer R ø ~10 12 cm (BSG) Rate( n m, TeV )prec > Rate( n m, 100 TeV )int.shock ( easier to detect in ICECUBE ) but, if WR (He core), R ø ~10 11 cm Rate( n m, TeV ) prec < Rate( n m, 100 TeV ) int.shock test progen. size high z : popiii?) If jet DOES NOT escape choked jet, ns escape, gs don t hidden n source If jet break-out: photon flashes (3) ò Blue n- spectrum: t100 TeV p,g n from shocks outside star

37 GRB : precursor (& SN shell?) with ICECUBE Burst of L g ~10 51 erg/s, E SN ~ z~0.17, q~68 o Prob.of n interaction E log10[ ν Φ ν /(GeV cm s )] Flux of n Supranova Precursor I Burst Precursor II Afterglow (wind) Afterglow (ISM) 8 d ν flux from GRB log10[ E ν / GeV] 1 d 0.1 d Razzaque, Mészáros, Waxman 03 PRD 69, 23001

38 Core collapse SN : slow jets? Spectrum and diffuse flux Razzaque, Mészáros, Waxman PRL (astroph/ ) 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, pg πµ n (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 upmu), negligible background, in km 3 detectors - ICECUBE

39 Diffuse UHE n from pop.iii collapse Recent AMANDA u.l. At z~5-30(?) pop.iii, Mø ~ M Ÿ, core coll BH+ accr. Buried jets pg n m, n-bursts (but: dep. on ørot.rate) E iso ~ (?) erg (dep. on BH mass, dm/dt) Detect high z øform n, primordial IMF New (8/04) : can constrain w. AMANDA latest results: E iso ~10 56 erg only for 1%, E iso erg for 50%! Schneider, Guetta, Ferrara aph/

40 Model-dependence of predictions & detectability of GRB n E n ~100 TeV (simult.) are least model dependent (use observed MeV g & same shocks as accelerate e ± ) E n ~1 TeV : (precursor) more model dependent, ( assume collapsar, sub-stellar jet, and R ø t cm ) E n ~ ev : (afterglow) need assume reverse shock prompt opt flash is ubiquituous (?) E n ~ 5 GeV: (decoupling) p,n likely, but detection needs special instrumentation E n ~5-100 TeV : (pop III) speculative; very massive star envelope ejection and rotation rate? Constraints useful E n ~0.3-1 TeV : (cc SN) if semi-rel. jets (fraction?)

41 Radio-quiet (core) AGN ns AGN are powered by accretion on massive ( M Ÿ ) BHs 90% of AGNs are radioquiet (no jets), core X-ray Core emission model: aborted jet cloud collisions shocks p accel pg n Diffuse flux: already constrained by latest AMANDA results Alvarez-Muñiz & Mészáros, astro-ph/

42 Other Implications of GRB UHE 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)

43 Conclusions UHE n will allow test of proton content of jets, test shock accel.physics, magn. field If UHE n NOT detected, jets are MHD! Probe n interactions at t TeV CM energies Test SR, oscillations, masses, vacuum disp. Constraints on stellar evolution and death, star formation rates at redshifts of first structures Could be probes of pop III first gen. Objects May test SN-GRB connection & transition New physics: need know boundaries of SM astrophysical UHENU mechanisms