very high energy gamma-rays from the galactic centre measured by h.e.s.s
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Loïc Rolland SISSA 2005 – Trieste, 2005 1
Very high energy gamma-rays
from the Galactic Centre
measured by H.E.S.S.
L. Rolland (CEA-Saclay/DSM/DAPNIA/SPP, Gif-sur-Yvette, France)
for the H.E.S.S. collaboration
(rollandl@in2p3.fr)
The H.E.S.S. detector
The Galactic Centre
Observations of the Galactic Centre with H.E.S.S.
Loïc Rolland SISSA 2005 – Trieste, 2005 2
The H.E.S.S. experiment
Loïc Rolland SISSA 2005 – Trieste, 2005 3
Imaging Atmopheric Cherenkov
TelescopesGamma-ray
Cosmic rayParticle
shower
Che
renk
ov li
ght
muon
Gamma-ray candidate
hadron
Atmosphere = calorimeter
Image of Cherenkov flashs (~3 ns)
Loïc Rolland SISSA 2005 – Trieste, 2005 4
Stereoscopic system
Gamma-ray
Cosmic ramy
Particle
shower
Che
renk
ov li
ght
Gamma-ray
Cosmic ray
Particle
shower
Che
renk
ov li
ght
1
2
3
4
Impact
parameter
of the
gamma-ray
Rejection of isolated muons at trigger level
Energy threshold decreased
Hadronic rejection improved
Gamma-ray reconstruction improved Source
direction
Loïc Rolland SISSA 2005 – Trieste, 2005 5
The H.E.S.S. experimentSite : Namibia, 23°16'' S, 16°30'' E, altitude 1800 m
Loïc Rolland SISSA 2005 – Trieste, 2005 6
Real performancesTrigger rate ~ 400 Hz
Dead time ~ 10%
Field of view 5°
Threshold ~ 100 GeV at zenith
Angular resolution ~ 6' gerbe to gerbe
Energy resolution ~ 15%
Crab Nebula detection at zenith:0,01 Crabe : ~25 h0,05 Crabe : ~1 h0,10 Crabe : ~15 min1,00 Crabe : ~10 s
Loïc Rolland SISSA 2005 – Trieste, 2005 7
The first sources seen by H.E.S.S.
16 galactic sources
4 extragalactic sources
May 2005
+ ~5 galactic sources (1 microquasar)
+ ~4 extragalactic sources
Loïc Rolland SISSA 2005 – Trieste, 2005 8
H.E.S.S
Loïc Rolland SISSA 2005 – Trieste, 2005 9
H.E.S.S. Galactic survey (2004)
HESS J1702-420HESS J1713-381 HESS 1632-478
330°
RX J1713.7-3946HESS J1640-485
HESS J1616-508
HESS J1614-518
359°
HESS J1708-410 HESS J1634-472HESS J1745-303
LS 5039
HESS J1804-216 Gal. Centre HESS J1837-069
G0.9+0.1 HESS J1813-178 HESS J1825-137
HESS J1834-087
30° 0°
Sources > 6 sigma (9 new, 11 total)Sources > 4 sigma (7 new)
Loïc Rolland SISSA 2005 – Trieste, 2005 10
Supernova remnants
Excess map
(number of -rays)
X-ray contours:
ASCA
RXJ 1713-
Loïc Rolland SISSA 2005 – Trieste, 2005 11
Plerions
Chandra, X
MSH 15-52
Excess map
(number of -rays)
X-ray contours:
ROSAT
Loïc Rolland SISSA 2005 – Trieste, 2005 12
New type of VHE sources: microquasarMicroquasar: Microquasar:
LS5039LS5039
H.E.S.S.
Observations
of LS 5039
Aharonian et al. Science (2005)
First VHE detection of a microquasar
Expect a strong attenuation in the photon field of the
star
Emission further away from compact object
Jets (microblazar) ? Or other mechanism
Variablility expected,
needed to constrain the
models (shorter time scale
as in blazars / orbital period)
Being reobserved in 2005,
already significant
signal (16 sigma)
2005 data analysis under way
Loïc Rolland SISSA 2005 – Trieste, 2005 13
VHE unidentified sources
Known (2003): TeV 2032 HEGRAGalactic Center CANGAROO, Whipple, HESS, MAGIC
Is there are new population of “dark” TeV emitters ??Extended, structuredPower law energy spectrum, photon index ~2.2
New Sources (2005):J1303-631 HESS J1614-518 HESS J1804-216, “ J1804-216 “
Unconfirmed:3EG J0520+2556 Milagro [Dingus]
IMAGES
SOURCES
HESS
Loïc Rolland SISSA 2005 – Trieste, 2005 14
62Unidentified
117AGN (e.g. Mkn 421, PKS 2155 …)
61 Pulsar Wind Nebula (e.g. Crab, MSH 15-52 …)
3212TOTAL
20Diffuse (Cygnus region, GC region)
10Micro-quasar (LS 5039)
10Binary Pulsar (B1259-63)
62Supernova Remnants (e.g. Cas-A, RXJ 1713 …)
2005 2003Source Type*
Gamma-ray source count (ICRC 2005)
* Includes likely associations of HESS unid sources.
Explosion in the number of VHE sources.
Loïc Rolland SISSA 2005 – Trieste, 2005 15
The VHE sky - 1995
Mrk421
Mrk501
Crab
R.A.OngAug 2005
Pulsar Nebula
SNR
AGN
Other, UNID
Loïc Rolland SISSA 2005 – Trieste, 2005 16
The VHE sky - 2003
Mrk421 H1426
Mrk501
1ES1959
1ES 2344
PKS 2155
Cas A
RXJ 1713
CrabTeV 2032
M87
GC
R.A.OngAug 2005
Pulsar Nebula
SNR
AGN
Other, UNID
Loïc Rolland SISSA 2005 – Trieste, 2005 17
The VHE sky - 2005
Mrk421 H1426
Mrk501
1ES1959
1ES 2344
PKS 2155
Cas A
RXJ 1713
CrabTeV 2032
M87
PKS 2005
PSR B1259
RXJ 0852
MSH 15-52
SNR G0.9
HessJ1303
GC
R.A.OngAug 2005
Pulsar Nebula
SNR
AGN
Other, UNID
H2356
1ES 1218
1ES 1101
LS 5039Vela X
+ 8-15 add. sourcesin galactic plane.
CygnusDiffuse
Loïc Rolland SISSA 2005 – Trieste, 2005 18
The Galactic Centre
Loïc Rolland SISSA 2005 – Trieste, 2005 19
VHE candidates at the Galactic Centre
4° × 5°
A supermassive black hole:
Sgr A*
Loïc Rolland SISSA 2005 – Trieste, 2005 20
In the vicinity of the black hole
A supernova remnant
Sgr A East
20 cm- VLA
~4x3 pc
<1x1 pc
Loïc Rolland SISSA 2005 – Trieste, 2005 21
The GC seen by INTEGRAL
20-40 keV
40-100 keV
2° × 2°
Loïc Rolland SISSA 2005 – Trieste, 2005 22
The 2004 signal: HESS J1745-290
48 hours live time from March 30 to September 4, 2004
● pointing within 2 degrees of Sgr A*
● 0° to 60° zenith angle
<0.11° within Sgr A*:
● 38
● 1862
Loïc Rolland SISSA 2005 – Trieste, 2005 23
A new plerion: G0.9+0.1
● G0.9+0.1
● mixte morphology type SNR
● photon index ~2.3
● 3% Crabe flux
Loïc Rolland SISSA 2005 – Trieste, 2005 24
HESS J1745-290 - Angular distribution
Compatible with point-source in the very centre
Tail at larger distance
Loïc Rolland SISSA 2005 – Trieste, 2005 25
HESS J1745-290 - Position and extension
Assuming point-like source
compatible with Sgr A* 5.6''±10''±20''Diffuse emission
Assuming symmetric gaussian
distance to Sgr A* 3.9''±13''±20''
extension: 1.9' ± 0.23' 20 cm- VLA
Loïc Rolland SISSA 2005 – Trieste, 2005 26
Other high energy observations
Compatibility with
● INTEGRAL source (G1)
● black hole Sgr A*
● supernova Sgr A East
Incompatibility with
● unidentified EGRET source (99% CL)
Loïc Rolland SISSA 2005 – Trieste, 2005 27
HESS J1745-290 - Spectrum
Energy range:
166 GeV-37 TeV
Compatible with 2003 spectrum:
=2.2±0.09±0.15
(>1TeV)=(2.0±0.4±0.3)x10-12 cm-2s-1
Search for exponential cut-off:
Ecut
> 6 TeV (95% CL)
95% CL
upper limits
Loïc Rolland SISSA 2005 – Trieste, 2005 28
HESS J1745-290 - Light curves
Fit light curve by a constant:
2 probability
projection of the reduced flux
Night average flux
15% systematic errors added
Loïc Rolland SISSA 2005 – Trieste, 2005 29
HESS J1745-290 - Light curves
Light curves compatible with constant flux
15% systematic errors
added to every light curve points
Sensitivity of the method for a 5 detection of a flare:
nightly: x 2
28 minutes: x 4
10 minutes: x 7
Dataset P(Chi2) Sigmanightly 2003 73% 0.9 0.2nightly 2004 65% 1.0 0.1
nightly 2003-2004 50% 1.1 0.228-minutes 2004 41% 1.0 0.110-minutes 2004 94% 0.95 0.04
Loïc Rolland SISSA 2005 – Trieste, 2005 30
Astrophysical candidates
Loïc Rolland SISSA 2005 – Trieste, 2005 31
Emission from Sgr A*Sgr A* : supermassive black hole
variability energy spectrum
Loïc Rolland SISSA 2005 – Trieste, 2005 32
Emission from Sgr A EastSgr A East :supernova remnant
extension energy spectrum
Loïc Rolland SISSA 2005 – Trieste, 2005 33
Emission from Sgr A EastSgr A East : supernova remnant
extension energy spectrum
Source Photon index Luminosity (10̂ {34} erg/s) distance (kpc)
Crab 2,6 9 2
G0.9+0.1 2,3 4 8,5
MSH15-5-2 2,3 10 5
CG 2.3 12 8.5
Loïc Rolland SISSA 2005 – Trieste, 2005 34
Other possibilities
● Cosmic-ray interaction with dense medium
● Collision of stellar winds
● Other contributions:● transient sources observed in X-rays
Loïc Rolland SISSA 2005 – Trieste, 2005 35
Dark matter at the Galactic Centre
Loïc Rolland SISSA 2005 – Trieste, 2005 36
Shape of the DM halo
Halo density profiles
Extrapolations
Predictions
Large scale structure formation models
Loïc Rolland SISSA 2005 – Trieste, 2005 37
Gamma-ray: DM annihilation flux
WIMP nature
Neutralino annihilationlines are loop suppressedhadronisation (W± and Z
0 )
Kaluza-Klein annihilation
lines are loop suppressedcharged leptons and quarks
Dark matter halo
● Predicted gamma-ray annihilation flux:
continuum MSSM
Power law mKK
= 10 TeV
Cut-off
Loïc Rolland SISSA 2005 – Trieste, 2005 38
Gamma-ray: DM indirect detection
WIMP nature DM halo shape
Energy spectrum Angular distribution
● Predicted gamma-ray annihilation flux:
Loïc Rolland SISSA 2005 – Trieste, 2005 39
Only dark matter - Halo shape
Cherenkov telescopes
constraints DM halo shape
Diffuse emission
BUT
Angular distributioncompatible with cuspy halo ~ 1
Point-like source:
> 1.2
Loïc Rolland SISSA 2005 – Trieste, 2005 40
Only dark matter - Spectrum shape
Different spectra than Bergström and Profumo
Misuse of PYTHIA ?
Different spectra between Dark Susy and PYTHIA ?
Loïc Rolland SISSA 2005 – Trieste, 2005 41
Dark matter and astrophysical background
2 composonant spectrum:power lawDM annihilation
Spectrum compatible with power law
Upper limits on .v
● Shape of the halo: NFW
Uncertainties in density > 106
Loïc Rolland SISSA 2005 – Trieste, 2005 42
Dark matter and astrophysical background
99% CL upper limits
Loïc Rolland SISSA 2005 – Trieste, 2005 43
38 detection of
HESS J1745-290
in 2004
Position compatible
with Sgr A* within 6'' Slightly extended ? = 1.8'
Uncurved power law spectrum = 2.27
No indication of
variability in 2003-2004
Possible origin for the gamma-rays:● Sgr A*● Sgr A East● stellar wind collisions● cosmic-ray interactions in the dense medium● dark matter annihilations
Loïc Rolland SISSA 2005 – Trieste, 2005 44
38 detection of
HESS J1745-290
in 2004
Pure DM annihilation
spectrum incompatible
with the data
Loose constraints on .v
in case of astrophysical
background
Looking for other DM source candidates:
Sgr A Dwarf (25 kpc)
Canis Major (8 kpc)75.05.0~2.01.0~
GC
CMaj
GC
Sgr
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