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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
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