PL wed 1 Gaisser

Particle Astrophysics: 

Particle Astrophysics Cosmic rays Gamma-ray astronomy Neutrino astronomy

Multi-messenger astronomy: 

Multi-messenger astronomy Protons, g-rays, n, [gravitational waves] as probes of the high-energy universe Protons: directions scrambled by magnetic fields Photons: straight-line propagation but reprocessed in the sources extragalactic backgrounds absorb Eg > TeV Neutrinos: straight-line propagation, unabsorbed, but difficult to detect

Energetics of cosmic rays: 

Energetics of cosmic rays Energy density: rE ~ 10-12 erg/cm3 ~ B2 / 8p Power needed: rE / tesc galactic tesc ~ 3 x 106 yrs Power ~ 10-26 erg/cm3s Supernova power: 1051 erg per SN ~3 SN per century in disk ~ 10-25 erg/cm3s SN model of galactic CR Power spectrum from shock acceleration, propagation

Problems of simplest SNR shock model: 

Problems of simplest SNR shock model Expected shape of spectrum: Differential index a ~ 2.1 for diffusive shock acceleration aobserved ~ 2.7; asource ~2.1; Da ~ 0.6  tesc(E) ~ E-0.6 c tesc  Tdisk ~100 TeV  Isotropy problem Emax ~ bshock Ze x B x Rshock  Emax ~ Z x 100 TeV with exponential cutoff of each component But spectrum continues to higher energy:  Emax problem Expect p + gas  g (TeV) for certain SNR Need nearby target as shown in picture from Nature (April 02) Interpretation uncertain; see Enomoto et al., Aharonian (Nature); Reimer et al., astro-ph/0205256  Problem of elusive p0 g-rays

Spectrum normalizes atmospheric n: 

Spectrum normalizes atmospheric n GeV to TeV important for atmospheric n Good agreement < 100 GeV AMS, BESS Lack of TeV data; new expts: Magnetic spectrometers: PAMELA (2003) AMS on Space Station (2005) Meanwhile, new m-flux measurements Em > 100 GeV Timmermans’ talk on L3+C Somewhat below previous measurements

Knee of spectrum: 

Knee of spectrum Differential spectral index changes at ~ 3 x 1015eV a = 2.7  a = 3.0 Continues to 3 x 1018 eV Expect exp{-E / Z Emax} cutoff for each Z Fine-tuning problem: to match smoothly a new source with a steeper spectrum (Axford) How serious is this?

Speculation on the knee: 

Speculation on the knee

Transition to extragalactic origin?: 

Transition to extragalactic origin? Ankle new population of particles? Suggestive evidence: hardening of spectrum change of composition Measurements: Energy Depth of maximum (Xmax) Nm / Ne

Air shower detectors: 

Air shower detectors

Measuring the energy of UHECR: 

Measuring the energy of UHECR Ground array samples shower front Well-defined acceptance Simulation relates observed ground parameter to energy Fluorescence technique tracks shower profile Track-length integral gives calorimetric measure of energy Xmax sensitive to primary mass: Xmax ~ L ln(E0/A)

Xmax vs Energy: 

Xmax vs Energy Protons penetrate deeper into atmosphere Heavy nuclei develop higher up Plot shows a summary of data over 5 decades Several techniques Some dependence on models of hadronic interactions (R. Engel’s talk)

Xmax vs Energy: 

Xmax vs Energy Lines indicate trend of data: Light to heavy above the “knee” (~1016  1017 eV) Heavy to light at the “ankle” (~1018  1019 eV) AGASA looks at m/e ratio in shower front and sees no evidence for change of composition at the ankle

Energy of extragalactic component: 

Energy of extragalactic component Energy density: CR > ~ 2 x 10-19 erg/cm3 Estimate requires extrapolation of UHECR to low energy Power required >CR/1010 yr ~ 1.3 x 1037 erg/Mpc3/s 10-7 AGN/Mpc3 Need >1044 erg/s/AGN 1000 GRB/yr Need >3 x 1052 erg/GRB

Highest energy cosmic rays: 

Highest energy cosmic rays GZK cutoff? Expected from energy loss in 2.7o background for cosmological sources Attenuation length in microwave background

Compare AGASA & HiRes: 

Compare AGASA & HiRes Exposure (103 km2 yr sr): AGASA: 1.3 HiRes (mono): 2.2 Number events >1020 AGASA: 10 (+2?) HiRes (mono): 2? Both detectors have energy-dependent acceptance (different) Need more statistics and stereo results Ground array Fluorescence detector

Models of UHECR: 

Models of UHECR Bottom up (acceleration) Jets of AGN External Internal (PIC models) GRB fireballs Accretion shocks in galaxy clusters Galaxy mergers Young SNR Magnetars Observed showers either protons (or nuclei) Top-down (exotic) Radiation from topological defects *Decays of massive relic particles in Galactic halo Resonant neutrino interactions on relic n’s (Z-burst) Large fraction of g-showers (especially if local* origin) ( Incomplete list-- Refs. in written version ) If no cutoff, require a significant contribution from nearby sources. Local overdensity of galaxies is insufficient if UHECR source distribution follows distribution of galaxies.

Biggest event: 

Biggest event Comparison to Proton showers Iron showers g showers Fly’s Eye, Ap. J. 441 (1995) 295

Slide18: 

Most of shower absorbed, mostly muons survive to the ground Heavy primaries produce more m Incident photons produce few m Analysis of vintage (aged ~25 yrs) data from Haverah Park array possible with modern simulation tools Results place interesting limits limits on Top-Down models: UHE events from decaying, massive relics accumulated in the Galactic halo would be mostly photon-induced showers. Such models are therefore disfavored Similar limit on g/p from AGASA

Auger hybrid event: 

Auger hybrid event Fluorescence detector view Surface detector view “Engineering Array”: SD with 40 modules ~ 100 km2 viewed by fluorescence detector. Now operating in Argentina. 100 more tanks running in 2003.

Active Galaxies: Jets: 

Active Galaxies: Jets VLA image of Cygnus A Radio Galaxy 3C296 (AUI, NRAO). --Jets extend beyond host galaxy. Drawing of AGN core

Egret blazars: 

Egret blazars Blazars are AGN with jet illuminating observer. Two-component spectra interpreted as synchrotron radiation (low energy) plus inverse Compton generated by high-energy electrons accelerated to high energy in relativistic jets (G ~ 10). A few nearby blazars have spectra extending to > TeV observed by ground-based Imaging Atmospheric Cherenkov Telescopes (IACT).

AGN Mulitwavelength observations: 

AGN Mulitwavelength observations SSC, EC, PIC models 1st peak from electron synchrotron radiation 2nd peak model-dependent; predict n flux if PIC Interpretation complex: Sources variable Locations of peaks depend on source-- factor of >100 range of peak energy New detectors (GLAST, HESS, MAGIC, VERITAS) will greatly expand number, variety of sources

Slide23: 

Solar arrays for g-ray astronomy explore down to ~100 GeV: Celeste STACEE CELESTE, STACEE in operation

TeV g Blazars: 

TeV g Blazars Five detected Mrk 421 (Z = 0.031) Mrk 501 (Z = 0.034) 1ES2344+514 (Z = 0.044) 1H1426+428 (Z = 0.129) 1ES1959+650 (Z = 0.048)* * Whipple, IAU Circular 17 May 2002 Emax vs Z probes era of galaxy-formation through IR background

Blazar spectra at high energy: 

Blazar spectra at high energy Mrk 421 & Mrk 501, Cutoffs Intrinsic? Effect of propagation? Variable sources Low intensity – softer spectrum Interpretation under debate Need more observations of more sources at various redshifts HEGRA plots from Aharonian et al. astro-ph/0205499. Different Ecut of 421 and 501 suggest cutoffs are intrinsic. Comparable analysis of Whipple extends to lower energy. Seeing comparable cutoffs, they suggest effect is due to propagation. Krennrich et al., Ap.J. 560 (2002) L45 both at z ~ .03

Slide26: 

Sky map from the Milagro detector Milagro is a compact air shower detector that uses a 60 x 80 m water Cherenkov pool covered and surrounded by air shower detectors.

Detectors for gamma-ray astronomy: 

Detectors for gamma-ray astronomy Egret 1991-2000 Presently running Future AMS**Secondary Mode of operation *Multiple telescope arrays for stereo operation

Gamma-ray astronomypresent and future: 

Gamma-ray astronomy present and future A. Morselli, S. Ritz

H.E.S.S. : 

H.E.S.S. First events June, 2002

Gamma-ray bursts: 

Gamma-ray bursts Cosmological bursts Studies of afterglows (ROTSE, Beppo-Sax ID) determine Z ~ 1 Hypernova or coalescing compact objects Relativistic jets (G ~ 100) Acceleration at internal shocks Possible acceleration when jets interact with environment Are GRBs sufficiently powerful and numerous to supply the UHECRs? This question currently under debate Soft Gamma Repeaters Galactic magnetars, B ~ 1015 G Satisfy ebcBR > 1020 eV SWIFT to be launched in 2003

Neutrino Astronomy: 

Neutrino Astronomy SN1987A, Solar n High-energy n astronomy [DUMAND] Baikal, AMANDA Currently running Atmospheric n’s detected Limits on point sources, diffuse high-energy n’s, WIMPs, monopoles Km3-scale projects getting underway AMANDA: astro-ph/0205019 Skymap of upward events

South Pole: 

South Pole Dark sector AMANDA IceCube Dome Skiway

Expected sensitivity AMANDA 97-02 data: 

Expected sensitivity AMANDA 97-02 data 4 years Super-Kamiokande 8 years MACRO 170 days AMANDA-B10 10-15 10-14 m  cm-2 s-1 declination (degrees) southern sky northern sky

Slide34: 

Development of kilometer-scale n telescopes ... complementary sky-views and techniques IceCube in Antarctic ice Antares + Nemo, Nestor Km3 in the Mediterranean Sea

Skymaps and exposure to gamma-ray bursters: 

Skymaps and exposure to gamma-ray bursters BATSE 2706 GRBs Beppo-SAX 126 GRBs Plot by Teresa Montaruli is grey-scale image of sky coverage for upward events (black = no coverage, white = full coverage). Applies to En< PeV when Earth needed to shield against downward events.

Neutrino flavor ID: 

Neutrino flavor ID P  p  nm + m  e + ne + nm nm : ne : nt ~ 2 : 1 : 0 at production oscillations give 1 : 1 : 1 at Earth En < PeV nm: upward m track ne, nt: cascades En > PeV Rt ~ 50 m / Et (PeV) nt gives double bang or “lollipop” signature (large cascade preceded or followed by a long, “cool” track)

n Propagation in the Earth: 

n Propagation in the Earth Lower hemisphere 50% opaque for En ~ PeV Regeneration of nt nt  t  n  cascade: Look for excess of upward cascades between 0.1 and 10 PeV For En > PeV can use downward neutrinos as well as upward

Expected signals in km3: 

Expected signals in km3 Possible point sources: Galactic SNR 0 - 10 events / yr m-quasars 0.1 - 5 / burst ~ 100 / yr, steady source Extra-galactic AGN jets 0-100 / yr GRB precursor (~100 s) ~ 1000 bursts / yr ~ 0.2 events / burst GRB jet after breakout smaller mean signal / burst Nearby bursts give larger signal in both cases

Proposed detectors for En ~ EeV: 

Proposed detectors for En ~ EeV Air shower arrays Signature: Horizontal EAS Veff ~ 10 m.w.e. x area e.g. 30 Gt for Auger (Acceptance ~30 x larger for nt in Auger) >1000 Gt for EUSO, OWL Radio detectors RICE (antennas in S.P. ice) ANITA (antennas on long-duration Antarctic balloon) SALSA (…in salt domes) GLUE (Goldstone antenna search for n interact in moon) Note: despite larger Veff , rates may be comparable or smaller than in Km3 detectors with lower Ethreshold by an amount depending on source spectrum

Summary: 

Summary Need more statistics and cross-calibration for ultra-high energy cosmic rays Expect another leap in g-astronomy with GLAST and new ground telescope arrays Kilometer-scale neutrino telescopes to open new window on energetic Universe Many active and new experiments in this rapidly developing field -- stay tuned!

Diffuse galactic secondaries: 

Diffuse galactic secondaries p + gas  p0, p+/-, antiprotons p0  g g [p+/-  n] Hard g-spectrum suggests some contribution from collisions at sources Phys.Rev.Lett. 88 (2002) 051101

Lessons from the heliosphere: 

Lessons from the heliosphere ACE energetic particle fluences: Smooth spectrum composed of several distinct components: Most shock accelerated Many events with different shapes contribute at low energy (< 1 MeV) Few events produce ~10 MeV Knee ~ Emax of a few events Ankle at transition from heliospheric to galactic cosmic rays R.A. Mewaldt et al., A.I.P. Conf. Proc. 598 (2001) 165

Heliospheric cosmic rays: 

Heliospheric cosmic rays ACE--Integrated fluences: Many events contribute to low-energy heliospheric cosmic rays; fewer as energy increases. Highest energy (75 MeV/nuc) is dominated by low-energy galactic cosmic rays, and this component is again smooth Beginning of a pattern? R.A. Mewaldt et al., A.I.P. Conf. Proc. 598 (2001) 165

Reconstruction Handles for neutrino astronomy: 

Reconstruction Handles for neutrino astronomy

Energy resolution: 

Energy resolution Systematics DE / E ~20% for ~1018 eV By cross-calibrating different detectors By using different models By comparing spectra of different experiments and techniques Fluctuations in Smax underestimate E if measured at max, overestimate if past max

GRB model: 

GRB model Assumes E-2 spectrum at source 2.5 x 1053 erg/GRB 0.4 x 1037 erg/Mpc3/s Evolution like star-formation rate GZK losses included Galactic extragalactic transition ~ 1019 eV Bahcall & Waxman, hep-ph/0206217

AGN model: 

AGN model Assumes two-component spectra steep at high energy 1039 erg/Mpc3/s note high value Evolution, GZK losses Compares to AGASA data, cannot explain ~5 events Transition to extragalactic at low energy Berezinsky et al., hep-ph/0204357 Curves 2,3,4 with local overdensity of sources. 2 is observed overdensity.