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CANGAROO-II Detection of VHE gamma rays from the
Galactic Center
Indirect Search for CDMby
Imaging Atmospheric Cherenkov TelescopeR.Enomoto
ICRR
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Based on
• Three observations– Tsuchiya,Enomoto,Kusenofontov, et al (CANGAROO-
II), ApJ 606(2004)L115– Kosack,Badran,Bond, et al (Whipple), ApJ
608(2004)L97– Aharonian,Akhperjanian,Aye, et al (H.E.S.S), A&A
425(2004)L13
• Method– Enomoto,Yoshida,Yanagita,Itoh, ApJ 596(2003)216
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What is fundamental to be determined by experiments?
• Fundamental constants in fundamental equation: in view of particle physics;– Mass( SUSY energy scale), σSUSY( fundamental
coupling constant),,,• Those: already constrainted by cosmology;
– ΩCDM– σann by freezing condition.
• Those: cosmology needs;– ρCDM(x) ( spatial distribution, it’s better.),
• Therefore, Mass is most important, then σSUSY or ρCDM(x) .
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“Indirect” or “direct” search!• “Direct” search
– Search for collision with GeV scale.• Function of σNv, ρlocal. σN not exactly related with σann. ρlocal is
estimation and/or assumption (==0.3 GeV/cc).• O(M) ~Mp~O(GeV) and be overlapped with accelerator
experiments. LHC starts soon! (waste of money?)
• “Indirect” search is a direct measurement of fundamental parameters.– IACT ( and GeV-gamma, anti-matter )
• Search for secondary products, therefore called “indirect”.• Function of σannv, ρ. == direct cosmological parameters.• Mass direct determination. it covers to 100-TeV where
accelerator can not reach. Direct SUSY breaking parameter!• +Cosmic-ray physics will be done.
• I strongly feel “bad naming”.
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(Satellite vs Ground) vs Accelerator
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Imaging Atmospheric Cherenkov Telescope (IACT)
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Original Sketch
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Mitsubishi’s design
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VERITAS(photomontage)
Four Networks
H.E.S.S.
CANGAROO-III
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Introduction to GC for cosmic-ray physics
Strong Radio sourceSgr A*
High Energy Particleis there!
Strong IRHigh molecular densityNot clearly seen
via visible lightX-ray sourcesStrong GeV gamma-rays
All wave lengthtime variable~month/year
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Matter distribution
Shodel,Ott,Genzel, et al, Nature 419(2002)694
Black hole ~4 x 106M⊙
@center
IACT Δθ~3 arc mind(GC)=8.5kpc
10pc region = “cusp”
ρ~3000(r/10pc)-1.8[M⊙/pc3]~100(r/10pc)-1.8[TeV/cc]>105ρlocal
Annihilation rate ∝ ρ2
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Performances of IACTs
Whipple: Original IACT, Crab, Mkn421, Mrk501,,,,
CANGAROO-II: RX J1713.7-394, 0852-4622,supernova remnant & GC
H.E.S.S.: RX J1713.7-3946, 0852-4622 confirmation + Now many.
Flux1713(C-II)~Flux(H.E.S.S)Shell like (moon size)
@HDGS_04 by W.Hofmann
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Three observationsCANGAROO-II(2001,2002) Whipple(1995-2003)
H.E.S.S.(2003)
Size<47pc
Size<7pc
Size<37pcMAGIC
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Three Fluxes
Taken from H.E.S.S. paper
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Including C-II energy systematic
Taken from H.E.S.S. paper
+1σ-1σ
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Cosmic-ray interpretation works! See papers!
Energy flow distributions: spectral energy distribution (SED)
Anyway!
But it is only a few SN-equivalent energetics!Why our Galactic Center is so quiet???It is not giving a significant contribution to the origin of cosmic-rays
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If they are due to CDM, see semi-log plots in familiar scale,
log-log to semi-log plot!
Looks like a fundamental interaction! Cosmic-rayshould be power-law! Absolutely not monochromatic!
At first, we only useCANGAROO-II data.
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• Energy scale exists!• Scaling cross section
(fragmentation function) is exponential!
• e+e- qqbar γX• Data available.• Combination of three
exponential functions.
Familiar spectrum (as an ex-high-energy physicist)
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CDM annihilation rate
• Annihilation rate@source– <σv>Bqqn2V
• σ: annihilation cross section• v: relative velocity ~300km/s• Bqq: branching ratio to qqbar• n: number density• V: total volume (~47kpc sphere)
• γ flux@earth– <σv>Bqqn2V/4πd2
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Method
• We are not insisting that these radiation are due to CDM annihilation.
• Cosmic-rays might be dominant contribution.– Therefore, satellite data for 2σ UL – + TeV data– Assume core.– Find maximum ρ(CDM) for χ2=χ2
min+4• 2σ UL
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Upper limits χχ → qq-bar
6TeV/ccApJ 606(2004)L115
× (Bσv26)-0.5
Use Bσv26=(Bσv/10-26cm3s-1)
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Navarro, Frenk, White, ApJ 462(1996)563
• Universal profile of CDM == “Cusp”• ρ ∝ 1/(r/rs)[1+(r/rs)]2
– Further studyρ ∝ 1/(r/rs)β[1+(r/rs)]3-β
• β=1.3? ⇒ Enhancement of > 1000– Matter distribution β=1.8
• ρlocal ~< 6 GeV/cc??? Nice UL??? Present local density estimation is 0.3 GeV/cc.
× (Bσv26)-0.5
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Upper limits χχ → γγ not good compared to qq-bar mode if
B(γγ)/B(qq)<0.025 with ΔE=40%
30TeV/cc
NGC253
× (Bσv29)-0.5
This always worsethan continuumassumption,therefore,we do not use thishereafter.
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See best fits for qq-bar mode
Energy Spectra good fit! Satellite experiments does not contribute,------GLAST will not help in this energy region.
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Best values??
M=1TeV, ρ=7TeV/ccρ=ρsun x 1000? × (Bσv26)-0.5
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Total mass limit of CDM < gravitational mass
Schodel et al, Nature 419(2002)694
108Msun@47pc
Our limit=7x107Msun=30MBH
NGC253-caseM<2000M253
× (Bσv26)-0.5
× (Bσv26)-0.5
Note that this slide is most important in this talk and all arguments onlydepend on (Bσv26)-0.5
GC-case
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Let’s play a game with all published results!
C-II
H.E.S.S.Whipple
Energy [TeV]
dF/d
E [c
m-2
s-1Te
V-1
]
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Upper or Lower
“maximal” “miminal”
dF/d
E [c
m-2
s-1Te
V-1
]
Energy [TeV] Energy [TeV]
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Most aggressive one (H.E.S.S. data)
dF/d
E [c
m-2
s-1Te
V-1
]
Energy [TeV]
Cosmic-ray BGpower law
Subtracted
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Compare with Gravitational MassH.E.S.S. onlyMatter density @ 7pc
With H.E.S.S&Whipple
CANGAROO-IIONLY
Matter density @ 47pc
H.E.S.S. acknowledged!
subtracted
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Normalized to matter density
Matter density = 1 C-II only
+ H.E.S.S.&W
H.E.S.S. Only
subtracted
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If you limit Cuspy power law!
Moore
NFW
Others
All matter
Is it a nice limit????
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See how UL limitsBlue: 1,2,3TeV with 190 TeV/cc@7pcYellow: 1,2,3TeV with 6TeV@47pc
This means that no more than 100% gravitational mass allowedFor CDM.
Energy [TeV]
dF/d
E [c
m-2
s-1Te
V-1
]
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Consider how “Indirect Searches”
work?
“Direct Searches” are multi-orders far from us.
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Assume: ρ(CDM)=ρ(matter)r(CDM)=r(matter)
FOM: MG2d-5(Δθ)-3
Figure-of-merit search for better targets
Targets as many as stars!
M31 Andromeda (too wide ~3 dergee)! Notsuitable.
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Giant Radio Galaxy Cen A
M=10M253
φ=0.3 degree
d=3.5Mpc~NGC253
a factor of ten improvement
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ω-Cen: globular cluster, largest, oldest, as heavy as small galaxy.
d=5kpc<dGCφ=0.6degreeM=5x106Msun
~1/2M47pc
expected limit~0.1Mω
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Sculptor Group
Cluster of Dwarf galaxies
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If you have an idea!
We are willing todirect our telescopesto your favorite targets!
Now 4-Telescopes areare working!
Call [email protected]
