The VHE gamma-ray skyviewed with H.E.S.S.Werner HofmannMPI für KernphysikHeidelberg

© Philippe PlaillyHESS = High Energy Stereoscopic System

H.E.S.S Imaging - induced air showersThreshold ~ 100 GeV Sensitivity ~ 1% Crab in 25 h

© Philippe Plailly

Gamma-ray

~ 10 kmParticleshower

Detection of Detection of TeV gamma TeV gamma rays rays

using Cherenkovusing Cherenkovtelescopestelescopes

~ 1o

Che

renk

ov li

ght

~ 120 m

Key issue:huge detection area~ 105 m2

(from Sky & Telescope)

M

Air showersAir showerslook a bit like meteorslook a bit like meteors

5 decades in frequency missing!

Thermal Emission

o ± ±

p + nucleus +X

Cosmic particle accelerators imaged using (secondary) gamma rays

Origin of Cosmic Rays ?Origin of Cosmic Rays ?

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

A tour of galactic particle accelerators:

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

alias Vela Junior

Supernova remnant shellsSupernova remnant shells

RXJ 1713.7-3946RXJ 1713.7-3946

Particle acceleration to beyond 100 TeV

Index ~ 2.0Cutoff or break at ~20 TeVIndex constant across SNR

E-2

Man-made accelerators

No

. of p

art

icle

s

Energy

How could cosmic accelerators work? How could cosmic accelerators work?

Man-made accelerators

No

. of p

art

icle

s

Energy

Nature’s accelerators

No

. of p

art

icle

s

Energy

EnricoFermi

How could cosmic accelerators work? How could cosmic accelerators work?

Energy gain / cycle E/E ~ shock

... many 100 cycles to reach TeV energies …

... takes several 100 years

Generates power law spectrum dN/dE ~ E-(2+)

… at some point, particle falls behind shock …

Peak energy ~1015 eV… depending on size of shock front …

typical Ep 10 E

Nonlinear process with efficiency ~50%!… accelerated particles generate plasma waves …

Nature’s accelerators

How could cosmic accelerators work? How could cosmic accelerators work?

No

. of p

art

icle

s

Energy

Puzzling: X-ray – Puzzling: X-ray – -ray correlation-ray correlation

Suzaku:Y. Uchiyama, T. TakahashiTexas Symp. 2006

HESSgamma rays

SuzakuX-rays

Contour lines: ASCA X-raysY. Uchiyama et al. 2002

H.E.S.S.

The Vela regionThe Vela region

Vela (Rosat)

Vela Juniord ≈200 pcage ≈ 700 y

Gamma ray sources & their physicsGamma ray sources & their physics

A tour of galactic particle accelerators:

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

Cosmology with gamma rays

Gamma ray sources & their physicsGamma ray sources & their physics

A tour of galactic particle accelerators:

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

Cosmology with gamma raysG21.5-0.9 in X-rays

Chandra / H.Matheson & S.Safi-Harb

Supernova shell

PWN

Vela-XVela-X

ROSATcontours

Chandra

Peak energy output at ~10 TeV

PulsarPulsarwindwindnebulaenebulae

-ray sourcesare

extended O(10 pc)displaced from pulsar

Morphology of gamma-ray sources:Morphology of gamma-ray sources:HESS J1825-137HESS J1825-137

> 2.5 TeV1 – 1.5 TeV< 1 TeV

> 2.5 TeV1 – 2.5 TeV< 1 TeV

> 2.5 TeV1 – 2.5 TeV< 1 TeV

Gamma ray sources & their physicsGamma ray sources & their physics

A tour of galactic particle accelerators:

Supernova remnantsPulsar wind nebulaeBinaries “Dark sources”Galactic center & DM (?)Cosmology with gamma rays

Gamma ray sources & their physicsGamma ray sources & their physics

Microquasar

LS 5039• 4 (?) M object in eccentric

3.906-day orbit around 20-30 M star

• closest approach ~1012 cm or ~2 stellar radii

Gamma-rayperiod:3.908±0.002 days

Spectral variationSpectral variation

unique chance to“experiment” witha cosmic source byvarying conditions

Modulation due toabsorption by e+e-

Gamma ray sources & their physicsGamma ray sources & their physics

A tour of galactic particle accelerators:

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

Cosmology with gamma rays

““Dark” sources: Objects Dark” sources: Objects which only shine in gamma rays ! which only shine in gamma rays !

… without plausible counterparts in X-rays, radio, …

Not all remain dark: HESS J1813-178Not all remain dark: HESS J1813-178promoted from unidentified source to SNR / PWNpromoted from unidentified source to SNR / PWN

White et al. 2005Brogan et al. 200520 cm VLAUbertini et al., 2005Integral

HESS J1813-178Radio Supernova shellD.J. Helfand et al., astro-ph/0505392 C.L. Brogan et al.,astro-ph/0505145

TeV size

S. Funk et al., astro-ph/0611646

XMM

HESSsensitivity

Explanations …Explanations …

Old supernova remnants (Yamazaki et al., astro-ph/0601704)Old PWNGBR remnants (Atoyan et al., astro-ph/0601704)

Basic idea: electrons are gone in old objects

Stellar winds / OB assoc.DM halo objects

A tour of galactic particle accelerators:

Supernova remnants Pulsar wind nebulae Binaries “Dark sources” Galactic center & DM (?)

Cosmology with gamma rays

Rainer Schödel

The center of our GalaxyThe center of our Galaxy

Galactic plane

Sgr A EastSNR (radio)

Sgr A*

HESS error circle

H.E.S.S.

The center of our GalaxyThe center of our Galaxy

Galactic plane

H.E.S.S.

Point sources subtracted

The center of our GalaxyThe center of our Galaxy

Galactic plane

H.E.S.S.

p

“Diffuse” -rays tracingmolecular clouds

Origin of the GC gamma rays ?Origin of the GC gamma rays ?Top-down: Annihilationof dark matter

particles qq, gg

Generates characteristic density profile:sharp spike with long tail

and characteristicenergy spectrum~ quark fragmentation + some decays

Is it DM? Is it DM? Angular distribution Angular distribution

PRL, in press

H.E.S.S. PSF

NFW Dark Matter

Is it DM? Is it DM? Angular distribution Angular distribution

PRL, in press

Diffuse emissionsubtracted

H.E.S.S. PSF

10-13

10-12

10-11

0,1 1 10

E2 F

(E)

[Te

V/c

m2 s]

E [TeV]

Is it DM? Is it DM? Spectrum Spectrum

Preliminary

20 TeV Neutralino

20 TeV KK particle proposed beforeH.E.S.S. data

proposed after early H.E.S.S. data

Extragalactic TeV astronomyExtragalactic TeV astronomy

Physics of AGN jetsCosmology: Density of cosmological extragalactic background light (EBL)Quantum gravity & exotics

1 minute bins

15 x Crab flux PKS 2155-304MJD 53944

Variability time scale ~ 3 minRs/c ~ 150…300 min (1…2 x 109 M)

Fast variabilityFast variability

… … and quantum gravityand quantum gravity

© Lynette Cook