The origin of NORMAL cosmic rays First results from H.E.S.S. Werner Hofmann MPI für Kernphysik Heidelberg
High Energy Stereoscopic System 4 Cherenkov telescopes on a 120 m square located in Namibia full system operational since Dec. 03 David Berge Stefan Funk MPI Kernphysik, Heidelberg Humboldt Univ. Berlin Ruhr-Univ. Bochum Univ. Hamburg Landessternwarte Heidelberg Univ. Kiel Ecole Polytechnique, Palaiseau College de France, Paris Univ. Paris VI-VII CEA Saclay CESR Toulouse GAM Montpellier LAOG Grenoble Paris Observatory Durham Univ. Dublin Inst. for Adv. Studies Charles Univ., Prag Yerewan Physics Inst. Univ. Potchefstroom Univ. of Namibia, Windhoek
Gamma ray Air shower ~ 10 km Detection of TeV gamma rays with Cherenkov telescopes Cherenkov light ~ 1 o ~ 120 m
960 PMT pixels 0.16 o pixel size 5 o field of view electronics in camera body (1 GHz analog sampling ASIC) 107 m 2 mirror area 382 mirror tiles automatic remote alignment guide telescope radiometer OO analysis software Root, CORBA
Point spread function All telescopes identical Agreement with simulations Stable over (2) years
Progress Detection of TeV gamma rays from the Crab Nebula Whipple 1989: 50 h observation time HEGRA 1997: 15 min HESS 2004: 30 sec
H.E.S.S. Sensitivity
Physics with H.E.S.S. Sources and acceleration mechanisms of (galactic) cosmic rays Astrophysics of compact objects (pulsars, stellar-mass black holes, AGNs, ) Cosmology Astroparticle physivs (dark matter search)
Things which will not happen in Namibia
other things do happen
H.E.S.S. 2002/3 data sample Objekt Type Time [h] 2002 2003 1ES 0323+022 AGN 16 Cen X-3 X-ray Binary 48 Crab Nebula Plerion 39 45 M87 AGN 92 NGC 253 Starburst-Galaxy 28 61 PKS 2005-489 AGN 15 68 PKS 2155-304 AGN 39 162 PSR B1706-44 Pulsar / Plerion 77 RXJ 1713.7-3946 Supernova-Remnant 77 SN 1006 Supernova-Remnant 198 Sgr A East Galaktic Center 42 TeV J1915.2+1147 Unident. TeV Source 27 Vela SNR Supernova-Remant 43 Others 58 60 Total 179 h 1016 h No. of events 74 M 644 M 1 Tel. 2/3 Tel.
Crab Nebula: The standard candle
Crab nebula Early data no background subtr. H.E.S.S.
Source mechanisms kev GeV TeV p int. ~ ρ 2 ISM Synch. ~ B 2 IC ~ ρ photon field Proton acceler. Electron accelerator
Galactic center A fascinating mix of potential VHE sources
TeV gamma rays from GC Tsuchiya et al. 2004 67 h on H.E.S.S. tight cuts no backgr. subtraction Kosack et al. 2004 26 h CANGAROO 2001/2002 > 10 σ Whipple 1995 2003 3.7 σ
Possible origins Shocks in Sgr A* accretion flow or jet Acceleration in Supernova shocks (Sgr A East) Acceleration in stellar winds from OB clusters Diffuse CR interacting with gas (ρ~10 3 /cm) Proton acceleration near event horizon and curvature radiation Neutralino / Wimp annihilation Source location, source size Time variability Energy spectrum
H.E.S.S. on off H.E.S.S. psf Point source (size < 3 or 7 pc)
Source location Chandra GC survey NASA/UMass/D.Wang et al. CANGAROO (80%) H.E.S.S. Whipple (95%) Contours from Hooper et al. 2004
H.E.S.S. 68% 95% Sgr A* Chandra F. Banagoff et al. 1.6
Galactic center spectra 2001/2 none of the individual experiments sees variability F CANGAROO (> 200 GeV) ~ Crab! H.E.S.S. should see it in minutes 1995-2003 2003
Spectrum: could it be DM? CANGAROO spectrum consistent with 2 TeV WIMP 10-7 H.E.S.S. spectrum requires > 12 TeV WIMP WIMPS > 1 TeV are disfavored in most models Need rather large WIMP density or cross section to explain flux E 2 dn/de 10-8 10-9 Wimp annihilation spectra have a cutoff at ~(0.2 0.3) Mχ 0,1 1 10 Energy [TeV] 6 TeV WIMP 15 TeV WIMP
Galactic center: PMT currents
Best guess (?) Sgr A East SNR Sgr A East Chandra & Radio NASA/G.Garmire (PSU) F.Baganoff (MIT) Yusef-Zadeh (NWU) H.E.S.S. limit on rms source size
Gamma emission by SNR The origin of cosmic rays p + nucleus π +X π o γγ π ± µ ± ν
How might such cosmic accelerators work? Man-made accelerators
How might such cosmic accelerators work? Man-made accelerators No. of particles Energy
How might such cosmic accelerators work? Man-made accelerators Nature s accelerators No. of particles Energy Enrico Fermi No. of particles Energy
How might such cosmic accelerators work? Energy gain / cycle E/E ~ β shock... many 100 cycles to reach TeV energies... takes several 100 years Generates power law spectrum dn/de ~ E -2-ε at some point, particle falls behind shock Peak energy ~10 15 ev depending on size of shock front Nonlinear process with efficiency ~50%! accelerated particles generate plasma waves Nature s accelerators 10% required to generate cosmic rays from supernovae In rest frame of shock front
Classical southern SNRs CANGAROO RXJ1713.7-3946 H.E.S.S. Kifune ICRC 2003
First TeV source with resolved morphology! Hard RXJ cuts, 1713 with H.E.S.S. no background subtraction
RX J1713 Spectrum H.E.S.S.: full remnant CANGAROO: hotspot Index 2.84±0.15±0.20 Index 2.2±0.07±0.1 preliminary
Classical southern SNRs cont d CANGAROO SN 1006 H.E.S.S. significance map Kifune ICRC 2003 preliminary Tanimori et al., ApJ 497 (1988) L25 3.8 m telescope + conference proceedings
H.E.S.S. flux limits Time dependence? Integral Flux [cm -2 s-1] 10-11 10-12 Modeling CANGAROO 1996/97 HEGRA CT1 1999-2001 H.E.S.S. 99% UL 10-13 2003 Data Large B forfield CANGAROO (> 100 hotspot mg) suppresses with CANGAROO IC relative psf (0.23 to o ) X- rays Ambient 0,1 ISM density 1 seems 10 100 to be small (0.1/cm Energy 3 [TeV] ) no target for protons Size of SNR ~50 LY But small scale shocks < 1 LY (Chandra) Need O(mG) fields to cool electrons quickly enough
The crazy southern sky
H.E.S.S. & the old sources Southern hemisphere TeV sources Object PSR 1706-44 Vela SN 1006 RX J1713 Gal. center NGC 253 PKS 2155 Current status H.E.S.S.: not detected at level of old flux H.E.S.S.: not detected at level of old flux H.E.S.S.: not detected at level of old flux H.E.S.S.: 20 σ, spectrum & flux not incompatible H.E.S.S.: 11 σ, spectrum differs H.E.S.S.: not detected at level of old flux H.E.S.S.: 45 σ, flux reasonable; no earlier spectrum
Pulsars and & pulsar nebulae Exploring Extreme electrodynamics & GR Relativistic winds Acceleration in shocks
PSR 1706-44 Chandra Spindown lum. ~ 1% of Crab X-ray lum. ~ 0.01% of Crab TeV emission detected by Durham and CANGAROO-I,II Kifune et al. 1995 Chadwick et al. 1998 Kushida et al., ICRC 2003 E -1.2 Kifune, ICRC 2003 Preliminary ICRC 2003 Crab Flux E 2.2 IC prediction ~0.001 Crab Sefako & de Jager 2003, 2004 Integral flux Correlated points!
PSR 1706-44 preliminary Signal region θ 2 (Degr. 2 ) 14 h 2-telescope data taken during commissioning phase H.E.S.S. assuming point source
Pulsars and & pulsar nebulae cont d Lose some, win some
PSR B1259-63 -20 days Pulsar crosses disk Mar 04 +20 days CANGAROO Kawachi et al. 2004 A (2000) B (2001) Model: Ball & Kirk 2000 Complex time dependence depending on alignment of pulsar and stellar wind
PSR B1259-63 H.E.S.S. preliminary ~ 9 σ pre-periastron ~ 6 σ post-periastron Flux ~5% Crab Index 2.8±0.3(stat) Periastron ~ 10 days before periastron (Feb./March)
The 1259 field Feb. 04 March 04 H.E.S.S. preliminary Apr./May 04 First two T New unidentified TeV source, >13 σ ev sourc o es i n Looks extended at 0.2 level, steady flux s ingle -2.2 field! Flat spectrum (E ), ~10% Crab
H.E.S.S. Phase II Ideas for the future: larger telescope Lower threshold (~ 10-15 GeV) and increased energy range in stand-alone mode Improved sensitivity at higher energy (> 60 GeV) in coincidence mode Test bed for high-altitude telescope systems