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Typical sensitivity of modern arrays
(H.E.S.S., VERITAS) : 1% Crab in some 10 h
Threshold ~100 GeV
Angular resolution ~0.1o
MAGIC: Threshold ~25 GeV,
few % Crab sensitivity
H.E.S.S. Phase II
600 m2 dish, 2000 x 0.07o pixel camera
• Extends energy range down to ~30 GeV
• Improves sensitivity in 100 GeV – TeV
range in stereo mode
Photo montage
H.E.S.S. Phase II
Reality
MAGIC II: Stereo, 2 x 236 m2
First light ceremony
April 25, 2009
85 m
MAGIC II Positioning in 20 s
MAGIC II
MAGIC I
397 x 0.1o pixels (FoV 2o), 180 x 0.2o
MAGIC II
1039 x 0.1o pixels
FoV 3.2o
VERITAS
T1:
T2:
T3:
T4:
Jan 2005
Spring 2006
Fall 2006
Spring 2007
1200 ft2 mirror area
499 x 0.15o pixels
FoV ~3.5o
Fall 2009
VERITAS
2009:
• improved optical psf
• move T1 for better sensitivity
and angular resolution
Proposed upgrades:
• High-QE PMTs (+35%)
• Trigger upgrade (topology)
Fall 2009
CANGAROO III
Operational, but modest performance compared to other arrays
• Modest dish size (57 m2)
• Sea-level altitude
• Serious mirror deterioration (10% / year)
• Partly outdated camera hardware
TeV astronomy in India
TACTIC, Mt. Abu
MACE
356 m2
2011/12
PACT Array, Pachmari
x 25
First data: HAGAR Array, Hanle
Air shower arrays
MILAGRO
Water Cherenkov,
ceased operation
in 2008, after 7 years
Tibet III
Scintillator array
arXiv:0810.3757, 0804.1862
CR spectra, moon shadow,
Crab & Mrk 421, 3 hotspots
ARGO-YBJ
6700 m2 RPC carpet
arXiv:0907.1164, 0905.1189,
0811.0997
Sun & moon shadow in CR;
Crab & Mrk421, GRB search;
P-Air Xsection, pbar-p ratio
M. Amenomori et al., arXiv:0810.3757
Tibet III
Crab
ARGO-YBJ
S. Vernetto et al.
ICRC 2009
A. Abdo et al.
B. Milagro
C. arXiv:0801.3827
5o smoothed
Scale:
0.1%
Mrk 421
Crab
High-pass filtered
Outline
Instrument status
Surveying the Galaxy in VHE gamma rays
Source classes & their astrophysics
Supernova remnants
Pulsar wind nebulae
Unidentified / dark sources
Binaries
Stellar clusters
No DM, electrons,
Surveying the Galaxy in
VHE gamma rays
The Galactic Plane in gamma rays
52 objects
R. Chaves
ICRC 2009
L = 60o
almost all sources
extended
L = -85o
VERITAS survey of Cygnus region
A. Weinstein
ICRC 2009
TeV J2032+4130
(MAGIC)
Effective exposure
1.0o
0.8o
Source search with r=0.11o, 0.24o regions
No hotspots above 5s post-trials in base survey
Limits 3% Crab flux for point sources at points below 3s
8.5% Crab flux for extended 0.2o sources
MILAGRO survey
Cygnus region
Geminga
Crab
B. Dingus
J1908+06
Energy range ~5 … 100 TeV
Source sizes & shapes
For uniform distribution of
targets,
g-rays probe particle
distribution
Source
of particles
(e.g. pulsar)
Target “material”:
Gas for po production by protons
CMB, IR, optical for IC upscattering of
electrons
Typical lifetime of electrons
is 10s of kyr,
of protons 100s of kr
range 10s of pc,
unless confined by
strong magnetic
fields or radiative
losses
typically large &
diffuse sources
electrons are more
effective radiators
Supernova remnants
as cosmic ray sources (?)
SRN with resolved shells
Latest addition: SN 1006
expands in uniform environment above the
Galactic plane
2 – 4.5 keV X-rays
VHE g-rays
smoothed X-ray
contours
B?
Flux: 1% Crab
H.E.S.S. prelim.
SN 1006
Azimuthal profile:
VHE vs X-rays
M. Naumann-Godo
ICRC 2009
Moriond 2009
Spectral index ~2.4
Flux ~1% Crab
Energy spectra
For both regions
Acceleration in Supernova Remnants
Some (Experimentalist’s) Questions:
Do SNR shocks accelerate particles to VHE energies?
What is the p/e ratio among accelerated particles?
What is the acceleration rate / acceleration time?
Where does acceleration cut off? Do SNR accelerate CRs
up to the knee – are they Pevatrons?
How efficiently is shock kinetic energy converted to CR
energy?
e or p: Supernovae interacting with clouds
Wardle et al. 2002
IC 443
VERITAS
MAGIC
maser
IC 443
MAGIC 2007, arXiv:0705.3119
VERITAS 2007, 2008: arXiv:0810.0799
e or p: Supernovae interacting with clouds
W 28
arXiv:0801.3555
W 51 / G49.2-0.7
A. Fiasson,
ICRC 2009
maser
emission
H.E.S.S.
Also
0FGL J1923.0+1411
MGRO hotspot
SNR acceleration efficiency: RCW 86
Helder et al.,
Science 2009
RCW 86
Age 2 kyr (?)
Dist. 2.5 kpc (?)
H.E.S.S.
PSF
Chandra & XMM
Measured shock velocity 6000±2800 km/s (Chandra 2004,07)
Expected post-shock gas temperature 42…70 keV
Measured post-shock temperature
2.3±0.3 keV (Ha line width)
>50% of energy in non-thermal component
(C.L. ?)
Who no Pevatrons?
(A) Lack of gamma-ray statistics
RCW 86
G = 2.4±0.2±0.2
H.E.S.S.
arXiv:0810.2689
(B) Lack of source statistics
With decreasing shock speed, acceleration &
CR confinement become less effective
PeV particles only for some 100 … 1000 years
At any time maybe only few pevatrons in Galaxy
The dominant species:
Pulsar wind nebulae
Pulsars & pulsar wind nebulae
van der Swaluw, Downes, & Keegan 2003
G21.5-0.9
Chandra
SN shock
accelerates particles
for O(10 ky)
Pulsar sustains
pulsar wind nebula
for O(100 ky)
Interaction of shell and PWN
Vela X
H.E.S.S.
Pulsars & pulsar wind nebulae
Dominant population among Galactic VHE sources
Pulsar & X-ray PWN discoveries in VHE sources
Pulsars: G0.9+0.1, HESS J1809-193, HESS J1833-105, HESS
J1837-069, HESS J1857+026
X-ray PWN: HESS J1616-508, HESS J1640-465, HESS H1718-385,
HESS J1813-178, HESS J1833-105, HESS J1845-029
Very extended sources – 10s of pc
Often significant displacement from pulsar
Origin of emission sometimes
ambiguous (PWN or unresolved
SNR)
New PWN / PWN candidates
S. Wakely
ICRC 2009
VERITAS
G54.1 +0.3 / PSR J1930+1852
Chandra
LAT PSR
VERITAS
MILAGRO
Crab-like pulsar
1.2 x 1037 ergs/s
VERITAS point source
Boomerang / PSR J2229+6114
Black contours: radio, purple: CO
Also: MGRO source
PSR B1706-44 -
a pulsar with VHE history
CANGAROO III
ICRC 2009
H.E.S.S.
ICRC 2009
source size s = 0.6o
Crab-level flux
source size s = 0.3o
17% Crab
The most distant:
N 157B / PSR J0537-6910 in LMC
About 1% of spin-down
lumi of 5 x 1038 ergs/s
visible in 1-10 TeV g-rays
Consistent with
0FGL J0538.4-6856
(30 Doradus?)
XMM-Newton
H.E.S.S.
preliminary
6, 8.5, 11 s
H.E.S.S. contours
SN 1987a in FoV;
upper limits close to
predicted flux
Nu. Komin
ICRC 2009
VHE source
Milagro:
9 of 16 LAT PSR have
more than 3s in Milagro
at multi-TeV energies
(Abdo et al, in press)
PSR J2021+3651
0FGL J0634+1745
Sorted by
Spin-down flux
Clearest pattern: X-ray vs VHE luminosity
old
(105 y)
Old PWN are
X-ray dark
Old pulsars:
VHE emitting electrons
accumulate over 10s of kyr
Low B field – synchroton
falls below X-ray range
Young pulsars:
Mattana et al.
arXiv:0811.0327
young
(103 y)
VHE emitting TeV electrons
still building up; X-ray
emitting electrons already in
equilibirum
Higher B field
HESS J1303-631: a pwn?
Aharonian et al.,
astro-ph/0505219
M. Dalton
ICRC 2009
M. Dalton
ICRC 2009
Complex source morphologies
E. de Ona Wilhelmi
ICRC 2009
HESS J1023-575:
Combination of a hard source, compatible with
PSR J1028-5819, 0FGL J1028.6-5817)
and a softer source (Wd 2, OFGL J1024.0-5754)
0.75 to 2.5 TeV
above 2.5 TeV
First ground-based
detection of pulsed
emission from a
pulsar
MAGIC, Science 322, 2008
using special low-energy trigger
Origin of pulsed emission: outer gap
Emission from polar cap
and slot gap cut off around
10 GeV due to pair production
EGRET
MAGIC
Binaries
Gamma-ray binaries
H.E.S.S.
MAGIC
VERITAS
ICRC 2009:
New results
on 2nd orbit
H.E.S.S.
Periodic
emission
Binaries:
Laboratory to study how particle acceleration
reacts to periodically varying conditions
(radiation fields, B-fields, …)
MAGIC
MAGIC arXiv:0809.4254, ICRC 2009,
also VERITAS arXiv:0904.4422
LS I +61 303
Periodic variation
Of VHE flux along 4 orbits
Orbital frequency
MAGIC
3rd harmonic
Periastron
Stellar clusters
Young stellar clusters / star forming regions
Wd 2
Wd 1
W43 SFR
Collective stellar winds (OB, WR) ?
Colliding wind binaries ?
First SNR ?
First PWN ?
J1023–575
HESS J1848-18
Old stellar clusters: globular clusters
Object
M5
M13
M15
47 Tuc
47 Tucanae
(Chandra)
106 M, 23 pulsars
Fermi-LAT source
PSR Flux (C.U.)
5
< 0.6%
8
< 2%
< 2%
8
< 1.6%
23
< 2%
Exp.
VERITAS
MAGIC
VERITAS
VERITAS
H.E.S.S.
Limits within a factor of few from
fluxes predicted for shock acceleration
in colliding pulsar winds; constraints
on number of undetected PSR
Aharonian et al., arXiv:0904.0361
Anderhub et al., arXiv:0905.2427
McCutcheon, ICRC 2009
TeVCaT
75 objects
in default catalog
TeVCaT
19+ objects
newly announced
Will reach 100+ objects with current instruments
Improved instruments (soon) online (x 3)
Next generation in planning (x 10)