The origin of NORMAL cosmic rays First results from H.E.S.S. Werner Hofmann MPI für Kernphysik Heidelberg

Transcription

1 The origin of NORMAL cosmic rays First results from H.E.S.S. Werner Hofmann MPI für Kernphysik Heidelberg

2 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

3 Gamma ray Air shower ~ 10 km Detection of TeV gamma rays with Cherenkov telescopes Cherenkov light ~ 1 o ~ 120 m

4 960 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

5 Point spread function All telescopes identical Agreement with simulations Stable over (2) years

6 Progress Detection of TeV gamma rays from the Crab Nebula Whipple 1989: 50 h observation time HEGRA 1997: 15 min HESS 2004: 30 sec

7 H.E.S.S. Sensitivity

8 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)

9 Things which will not happen in Namibia

10 other things do happen

11 H.E.S.S. 2002/3 data sample Objekt Type Time [h] ES AGN 16 Cen X-3 X-ray Binary 48 Crab Nebula Plerion M87 AGN 92 NGC 253 Starburst-Galaxy PKS AGN PKS AGN PSR B Pulsar / Plerion 77 RXJ Supernova-Remnant 77 SN 1006 Supernova-Remnant 198 Sgr A East Galaktic Center 42 TeV J Unident. TeV Source 27 Vela SNR Supernova-Remant 43 Others Total 179 h 1016 h No. of events 74 M 644 M 1 Tel. 2/3 Tel.

12 Crab Nebula: The standard candle

13 Crab nebula Early data no background subtr. H.E.S.S.

14 Source mechanisms kev GeV TeV p int. ~ ρ 2 ISM Synch. ~ B 2 IC ~ ρ photon field Proton acceler. Electron accelerator

15 Galactic center A fascinating mix of potential VHE sources

16 TeV gamma rays from GC Tsuchiya et al h on H.E.S.S. tight cuts no backgr. subtraction Kosack et al h CANGAROO 2001/2002 > 10 σ Whipple σ

17 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

18 H.E.S.S. on off H.E.S.S. psf Point source (size < 3 or 7 pc)

19 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

20 H.E.S.S. 68% 95% Sgr A* Chandra F. Banagoff et al. 1.6

21 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

22 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 Wimp annihilation spectra have a cutoff at ~( ) Mχ 0, Energy [TeV] 6 TeV WIMP 15 TeV WIMP

23 Galactic center: PMT currents

24 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

25 Gamma emission by SNR The origin of cosmic rays p + nucleus π +X π o γγ π ± µ ± ν

26 How might such cosmic accelerators work? Man-made accelerators

27 How might such cosmic accelerators work? Man-made accelerators No. of particles Energy

28 How might such cosmic accelerators work? Man-made accelerators Nature s accelerators No. of particles Energy Enrico Fermi No. of particles Energy

29 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

30 Classical southern SNRs CANGAROO RXJ H.E.S.S. Kifune ICRC 2003

31 First TeV source with resolved morphology! Hard RXJ cuts, 1713 with H.E.S.S. no background subtraction

32 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

33 Classical southern SNRs cont d CANGAROO SN 1006 H.E.S.S. significance map Kifune ICRC 2003 preliminary Tanimori et al., ApJ 497 (1988) L m telescope + conference proceedings

34 H.E.S.S. flux limits Time dependence? Integral Flux [cm -2 s-1] Modeling CANGAROO 1996/97 HEGRA CT H.E.S.S. 99% UL 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 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

35 The crazy southern sky

36 H.E.S.S. & the old sources Southern hemisphere TeV sources Object PSR 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

37 Pulsars and & pulsar nebulae Exploring Extreme electrodynamics & GR Relativistic winds Acceleration in shocks

38 PSR 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 Chadwick et al 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!

39 PSR preliminary Signal region θ 2 (Degr. 2 ) 14 h 2-telescope data taken during commissioning phase H.E.S.S. assuming point source

40 Pulsars and & pulsar nebulae cont d Lose some, win some

41 PSR B days Pulsar crosses disk Mar days CANGAROO Kawachi et al A (2000) B (2001) Model: Ball & Kirk 2000 Complex time dependence depending on alignment of pulsar and stellar wind

42 PSR B 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)

43 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

44 H.E.S.S. Phase II Ideas for the future: larger telescope Lower threshold (~ 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