TeV-Gamma Ray Astrophysics

with the H.E.S.S. Telescopes

Thomas LohseHumboldt University Berlin

NordForsk Network Meeting in Astroparticle Physics

Bergen, November 10, 2006

H.E.S.S. CANGAROO III

MAGIC

Veritas

in construction

Cherenkov Telescopes (3rd Generation)

Cosmic ray origin and accelerationSupernova remnantsStarburst galaxiesClusters of galaxiesUnidentified galactic sources/surveys

Astrophysics of compact objectsAGNsMicro-Quasars & Stellar-mass black holesPulsarsGamma ray bursts

CosmologyDiffuse extragalactic radiation fields via cutoff in AGN spectra

Astroparticle physicsNeutralino annihilation in DM halos

TeV -Astronomy: The Physics Shopping List

H.E.S.S.High Energy Stereoscopic System

MPI für Kernphysik, Heidelberg

Humboldt-Universität zu Berlin

Ruhr-Universität Bochum

Universität Erlangen-Nürnberg

Universität Hamburg

Landessternwarte Heidelberg

Universität Tübingen

Ecole Polytechnique, Palaiseau

APC, Paris

Universite Paris VI-VII

CEA Saclay

CESR Toulouse

GAM Montpellier

LAOG Grenoble

Paris Observatory

LAPP Annecy

Durham University

Dublin Inst. for Advanced Studies

NCAC Warsaw

Astronomical Observatory Cracow

Charles University Prag

Yerewan Physics Institute

North-West University, Potchefstroom

University of Namibia, Windhoek

H.E.S.S. Site

Clear sky Galactic centre culminates

in zenith Mild climate Easy access Good local support

(UNAM etc.)

23o16’ S, 16o30’ E, 1800 m asl

Farm Göllschau, Khomas Hochland, 100 km from Windhoek

Farm Göllschau, Khomas Hochland, 100 km from Windhoek

H.E.S.S. Phase I

4 telescopes operational since December 2003Energy threshold (for spectroscopy): 100 GeV

Single shower resolution: 0.1Pointing accuracy: ≲ 20Energy resolution: 20%

June 2002 September 2003 February 2003 December 2003

960 pixel PMT cameraPixel size: 0.16°

On-board electronicsWeight: 900 kg

13m dish, mirror area 107 m2

382 spherical mirrors, f =15mPoint spread 0.03°-0.06°

1. Particle Acceleration in Supernovae

2. The Galactic Centre

3. The Gamma Ray Horizon

4. Gamma Rays from a Super-Massive Black Hole

5. Gamma Rays from a Micro-Quasar

Selected Results from H.E.S.S.

Supernovae

Synchrotron radiation

Pulsar Wind Nebula:Electron wind from central

pulsar heats the cloud

The Standard Candle for TeV -AstronomyCrab Supernova 1054 a.D. d = 2 kpc

optical

1 lig

htye

ar

But what about hadrons (protons and nuclei)?

Cassiopaeia A Supernova 1658 a.D. d = 2,8 kpc

X ray picture

“Shell Type” SNR:

• no electron wind from pulsar

• gamma signal from shell regions not totally drowned in that of electron wind

• good source class to observe hadron acceleration

resolution

H.E.S.S. 2004E 210 GeV

RX J1713.73946

resolution

H.E.S.S. 2004E 210 GeV

RX J1713.73946

First Resolved Supernova Shells in -Rays

H.E.S.S. 2005E 500 GeV

RX J0852.04622

Strong correlation with X-ray intensitiesStrong correlation with X-ray intensities

• SN-Shells are accelerating particles up to at least 200 TeV!• But are these particles protons/nuclei or electrons?

E2 d

N/d

E

log(E)

Stars

radio infrared visible light X-rays VHE -rays

CMB

Dust

CosmicElectron

Accelerators BEe

Electron or Hadron Accelerator?

Synchrotron Radiation Inverse Compton

e

e

EdNd

B, e

e

EdNd BEe

Cosmic Proton

Accelerators

, p

p

Ed

Nd Matter Density

0Synchrotron Radiation of Secondary Electrons

EGRET

2.0 2.0

B 7, 9, 11

GB 7, 9, 11

G

Electron accelerator fits for RX J1713.73946 :• Continuous electron injection over 1000 years• Injection spectrum: power law with cutoff

• IC peak not well described• B-field low for SNR shell

• large & injection rate bremsstrahlung important

• needs tuning at low E

αeE

B 10

G B 10

G

2.0, 2.25, 2.5 2.0, 2.25, 2.5H.E.S.S.H.E.S.S.

Continuous proton injection over 1000 years Injection spectrum: power law, index 2 Different cutoff shapes & diffusion parameters

Proton accelerator fit:

H.E.S.S. RX J1713.73946

Galactic Centre

HESS J1837069

HESS J1834087

HESS J1825137

HESS J1813178

HESS J1804216

G0.90.1HESS J1747281

Galactic CentreHESS J1745290

HESS J1745290

HESS J1713381

RX J1713.73946HESS J1708410

HESS J1702420HESS J1640465

HESS J1634472

HESS J1632478HESS J1616508

HESS J1614518

no visible cut-off rather large mass

measured flux large cross-section and/or DM density

Possible Interpretation: Dark Matter annihilation?

10-13

10-12

10-11

0,1 1 10

E2 F

(E)

[Te

V/c

m2 s]

E [TeV]

20 TeV Neutralino20 TeV Kaluza Klein particle

… unlikely !

H.E.S.S. MAGICGC

Crab

Galactic Centre Neighbourhood

~150 pc

Galactic CentreHESS J1745290

SNR G0.90.1HESS J1747281

EGRET GeV--sources

...point sources subtracted

first resolved detection of diffuse TeV--radiation cosmic rays (hadrons) interacting with molecular clouds

~150 pc

Galactic Centre Neighbourhood

molecular clouds density profiles

HESS J1745290

Cosmic Ray Spectrum at the GC...

diffuse radiation

expected flux for CR spectrum

observed on earth

Cosmic rays are much harder and have 3

larger density around the GC

Cosmic rays are much harder and have 3

larger density around the GC

is very different from the one at earth

Possible reason:

Close-by source population

Possibly single SN-explosion

The Gamma Ray Horizon

General Active Galactic Nuclei (AGN):• Supermassive black holes, M 109 M

• accretion disk and relativistic jets

Blazar-Typ: Jet points towards the earth• Doppler-boost TeV -radiation

Blazars

E

dN/d

E

Measurement of EBL ( Cosmology )

Physics of compact objects,acceleration/absorption in jets,…

EdN

/dE

Absorption in (infrared) extragalactic background light (EBL)

(TeV) + (EBL) e+e-

e+

e-

Cut-off Energy and -Ray Horizon

PG 1553113

H 2356 (x 0.1) = 3.1±0.2 Preliminary

EBL Unfolding of Measured Spectra

1 ES 1101 = 2.9±0.2

EBL

H 2356 (x0.1) = 3.1±0.2

Hardest plausiblesource spectrum = 1.5

Hardest plausiblesource spectrum = 1.5

Too muchEBL

Lower Limits(Galaxy Counts)

New Upper Bound on EBL Density

Direct IRTSMeasurements

Assumed shape for rescaling

H.E.S.S. upper boundfrom spectral shapes of

1ES 1101-232 (z = 0.186) H 2356-309 (z = 0.165)

EBL density seems 2 smaller than expected! Little room for EBL sources other than galaxies (early stars…)

Upper Limits

excluded by H.E.S.S.

M87Gamma Rays from

the Rim of a Super-Massive

Black Hole

M87• Radio Galaxy, Virgo Cluster, d 16 Mpc• Central 3 109 M⊙ Black Hole, RS 1015

cm

• Relativistic Plasma Jet at 30 Blazar

RadioVHE -Rays

host galaxy (optical)

99.9% c.l. extension upper limit

Is there a better way to constrain the source size?

v c

Yes, there sometimes is: Source variability!

source

R

time smearing: R/c

source variability: t* ≳ R/c

shortest observable variability: t ≳ R/c

upper limit on source size: R ≲ c t

θcosβ1Γδ 1

relativistic Doppler factor

reasonable: 1 50

Radio

optical

X-ray

nucleus

knots (jet)

Doubling times of 2 days observed during 2005 high state of M87

cm10R

Rδ5R15

S

S

• Knots in jet are excluded as sources• High energy particles created close to black hole horizon

Gamma Rays from a

Micro-Quasar

LS 5039

Periastron 0

Apastron 0.5

observer

inferior conjunction 0.716

superior conjunction 0.058

Massive star M 20 M⊙

compact object: 1.5-5 M⊙

neutron star or black hole?Orbital Period 3.9 days

Eccentric orbitbinary separation 2-4.5 R

*

LS 5039

Periastron 0

Apastron 0.5

observer

inferior conjunction 0.716

superior conjunction 0.058

Paredes et al. 2000

Faint X-ray emissionslightly variable

Extended pc-scale radio emission possibly from jets (v 0,2 c)

VHE -Ray Lightcurve folded with orbital period 0

0.5

observer

0.716

0.058

Modulation absorption in radiation field central emission ( 1au)

H.E.S.S.H.E.S.S.

VHE Spectral Modulation• modulation strength

strongly energy dependent

• not explainable by pure absorption effects

• complicated interplay between production & absorption mechanisms

The central engine starts to

reveal its physics

The Future: H.E.S.S. Phase II

• Large telescope under construction

• Improve sensitivity: 4 small 1 large better than 8 small

• Reduce threshold to O ( 20 GeV )

Summary• Very successful initial years of H.E.S.S. Phase I

• Many new sources & several fundamental discoveries

• The VHE -ray sky is well populated and complex

• Expect “bright” future