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• Partly outdated camera hardware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)