Download - PRESENT AND FUTURE DARK MATTER SEARCHES WITH I MAGING A TMOSPHERIC C HERENKOV T ELESCOPES
PRESENT AND FUTUREDARK MATTER SEARCHES WITH
IMAGING ATMOSPHERIC CHERENKOV TELESCOPES
J-F. GlicensteinIRFU, CEA-Saclay
Outline
− Imaging Atmospheric Cherenkov Telescopes− Indirect dark matter searches with IACT− Results on the Galactic Halo (H.E.S.S)− Dwarf Galaxies: Segue (MAGIC, VERITAS)− Galaxy clusters: Fornax (H.E.S.S)− Dark matter searches with CTA
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Major Active IACTs
H.E.S.S.
MAGIC
VERITAS
High Energy Stereoscopic System
located in Namibia, latitude=-23o, altitude=1800 m4 telescopes, 107 m2 eachcameras 960 PMTFOV= 5o
trigger threshold=100GeVinstalled: january 2004
installation of 5th telescope in 2011, first light expected 2012mirror: 600m2, 2048 PMT, FOV=3.5o, trigger threshold=20 GeV
Major Atmospheric Gamma-ray Imaging Cherenkov
located in La Palma (Canaries Islands),latitude=+29o, altitude=2225 mmirror: 234 m2
camera 534 PMTFOV=3.5o
trigger threshold=60 GeVinstalled late 2004installation 2nd telescope in 2009mirror 234m2, 1099 PMT
Very Energetic Radiation Imaging Telescope Array System
origin: Whipple collaboration (10 m, late 80s)located in Arizona,latitude=+32o, altitude=1275 m
4 telescopes, 106 m2 eachcameras 499 PMTFOV=3.5o
trigger threshold=100 GeVinstalled in april 2007
Gamma- ray
~ 10 kmParticleshower
~ 1o
Cher
enko
v lig
ht
~ 120 m
1
2
3
4− brief flash ~3 ns− steroscopy: cosmic ray background rejection improved gamma ray reconstruction
Imaging atmospheric Cherenkov telescopes
Present and future DM searches with IACT 8
VHE gamma-ray astronomy: catalog of sources
Moriond Cosmology 2012
The VHE gamma-ray sky (November 2011)http://www.mppmu.mpg.de/~rwagner/sources/
~100 sources (60 galactic)
Present and future DM searches with IACT 9
Indirect DM searches with IACTs
Moriond Cosmology 2012
)(MTeV 1
/10 3
2
326-
Jscm
vdEdN
dEd
WIMP annihilation flux into rays observed by an IACT:
particle model fAP: dark halo model
− Most current particle models:− neutralinos (MSSM)− U Extra Dimensions (Servant, Tait 2003) boson B− leptophilic models (PAMELA excess) − decaying dark matter
− Astrophysical factor: dense targets
Galactic Center nearby dwarf galaxies, globular clusters galaxy clusters (Fornax)
dark matter clumps
dlJfsolDM
AP ..
2
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Signal boosts: particle physics
Moriond Cosmology 2012
FSR IB
relative velocity b
– Sommerfeld effect:• effective low velocity dispersions
• resonances at:
– Internal Brehmstrahlung• annihilation to W+W-,ff
( heavy higgsino-like)
03.02 bcv
TeV45.4 22
2
nnMM Z
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Signal boosts: astrophysics
Moriond Cosmology 2012
• Boost effect B from unresolved DM clumps• estimated with Aquarius simulation (Springel et al 2008)• B sensitive the assumed value of Mlim ( Mlim
-0.226)• B ~ (a few) for point-like searches towards dwarf galaxies• B up to 2 order of mag. for extended searches (galaxy clusters)
Mlim = 10-6 M ⊙
Mlim = 5 10-3 M ⊙
Fornax galaxy cluster
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HESS searches towards the Galactic halo
Moriond Cosmology 2012
− 112 hours collected (2004-2008)− 1 degree around GC− galactic plane (|b| < 0.3o) excluded− background estimated by reflected bakground technique
Present and future DM searches with IACT 13
H.E.S.S. limits on WIMP annihilation in the Galactic halo
Moriond Cosmology 2012
Excluded 95% C.L.
mSUGRA models
A.Abramovski et al. (HESS), Phys.Rev.Lett 106, 161301 (2011)
Present and future DM searches with IACT 14
Searches towards globular clusters: M15
Moriond Cosmology 2012
UMiDrac
oM15 (adiabatic compression)
MSSM + WMAP constraints
Same (Woods et al) DM halo modelling
Excluded (95% CL)
HESS limit
• very small 0.04 pc core• low metalicity(“primordial”)• not dominated by DM
WHIPPLE
• Woods et al (Whipple) 2008: constraints at the 10-23 level (1.2 hour!)• A.Abramovski et al (HESS) ApJ 735 11 (2011): also at 10-23 level (15.2 h)• takes into account heating of DM by stars in GC core
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Dwarf spheroidal galaxies
Moriond Cosmology 2012
• dark matter dominated• mass range: 107-109 M ⊙• observed by IACTs:
Sagittarius, Carina, Sculptor, Draco,Willman1, Segue1, Umin, Canis Major, Boötes 1
• data on surface brightness,velocity dispersion, globular clusters,colors galactic structure wellmodeled
Walker et al 2007
Belokurov et al 2006
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Segue 1 dwarf galaxy
Moriond Cosmology 2012
− discovered 2006 in the SEGUE (Sloan) catalog by Belokurov et al.− located 23±2 kpc from the Sun− located at the intersection of Saggitarius and Orphan stellar streams− unclear whether dwarf galaxy or globular cluster− only 71 stars resolved. − velocity dispersion =3.7±1.5 km/s M = 5.8 106 M⊙−seems dominated by DM, but error on mass ~ 100%
log (core radius)
MV
GC dwarfgalaxies
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MAGIC observations of Segue1 dwarf
Moriond Cosmology 2012
− single telescope observations (MAGIC1), taken in 2008-2009− ~ 29.5 h good data− no evidence for signal− Segue 1 dwarf model was modelled as an Einasto profile (Essig et al 2010)− analysis in a slightly extended region ||< 0.14o ( = 10-5 sr)− J() = 1.78 1019 GeV5/cm2 sr
Emin = 100 GeV
Present and future DM searches with IACT 18
MAGIC searches towards Segue1: MSUGRA exclusion
Moriond Cosmology 2012
Excluded 95% C.L.
2 errors on J()(uncertainty on M)
J.Aleksic et al. (MAGIC), JCAP 06 035(2011)
<v>min ~ 10-23 cm3s-1
( t+t-)
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VERITAS observations of Segue 1 dwarf
Moriond Cosmology 2012
− 48.7 hours obtained in 2010 and 2011− no evidence for signal− same Einasto profile than the MAGIC paper− analysis in region q < 0.12o
− J() = 7.7 1018 GeV5/cm2 sr
-Emin = 300 GeV-Significance of signal inside q<0.12o: 1.4
-”contamination” by bright star(h-Leonis) -removed from background evaluation
target
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VERITAS searches towards Segue 1: exclusion limits
Moriond Cosmology 2012
<v> min ~ 2 10-24 cm3 s-1
(t+t-)
<v> from thermal models
Excluded 95% C.L.
E.Aliu et al (VERITAS), PRD 85, 062001 (2012)
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VERITAS searches towards Segue 1: boosts
Moriond Cosmology 2012
Wino-like neutralino self-annihilation self-annihilation to a 250 GeV particle pair
E.Aliu et al (VERITAS), PRD 85, 062001 (2012)
Excluded 95% C.L.
<v> from thermal models
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Searches towards Segue 1: leptophilic models
Moriond Cosmology 2012
A fraction of parameter space excluded by MAGIC @ low energyand VERITAS @ high energy
MAGIC
VERITAS
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Sagittarius dwarf galaxy
Moriond Cosmology 2012
old limits
− recent observations of Sgr stream allows better modellingof Sgr Dwarf (closest dwarf)
−update on former HESS limitsby Viana et al (AstroparticlePhysics 2012)
− should be detectable with CTA (Mwimp a few TeV,200 h observation)−However, expected signal from msecond pulsars in M54 (background)also detectable at 4-60
HESS
CTA
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The Fornax galaxy cluster
Moriond Cosmology 2012
−distance d=19 Mpc−central galaxy NGC1399 with a passive SMBH (109 M ⊙) − total mass ~ 1014 M ⊙ , extends over 1 Mpc (6o)− dark matter distribution well studied with X-rays, globular clusters, stars etc− 2 approaches in modelling:
− assume NFW profile with concentration param. from virial mass (RB02)− use directly measured profiles
Schuberth et al (2009)
X rays
GC
Present and future DM searches with IACT 25
H.E.S.S. observations of the Fornax galaxy cluster
Moriond Cosmology 2012
− 14.5 hours of data obtained in 2005− “minimal energy” of observations: Emin = 260 GeV− boost effect expected from substructure signal in extended regions− signal region:
−q < 0.1o, significance S = 2.3 −q < 0.5o, significance S=1.2−q< 1o, significance S=0.6
Present and future DM searches with IACT 26
HESS limits on Fornax: effect of source extension
Moriond Cosmology 2012
Present and future DM searches with IACT 27
H.E.S.S. results on Fornax: WIMPs exclusion
Moriond Cosmology 2012
A. Abramovski et al., arXiv1202.5494 (2012), accepted in ApJ.
Present and future DM searches with IACT 28
H.E.S.S limits on Fornax: KK models
Moriond Cosmology 2012
Present and future DM searches with IACT 29
HESS results on Fornax: boost factors
Moriond Cosmology 2012
Excluded 95% CL
Present and future DM searches with IACT 30
The next generation of IACTs: CTA (2015)
Moriond Cosmology 2012
low energy sectionEthresh ~ 10 GeV
4 ø=23 m telescopes
core array100 GeV-10 TeV23 ø=12 m telescopes
high energy section32 ø=5-6 m tel.on 10 km2 area
2 arrays: north+south all-sky coverage
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Sensitivity of CTA
Moriond Cosmology 2012
x 10 flux sensitivity gain
energy range increase
Flux sensitivity for a 50 h observation
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Dwarf galaxy searches with CTA
Moriond Cosmology 2012
Low energy High energy
Several arrays layout studied
SculptorSegue 1
Courtesy A. VianaD.Nieto
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dwarf galaxies with CTA (2)
Moriond Cosmology 2012
Boos
t fa
ctor
A signal from Willman 1 or Segue 1 may be observable with CTAdepending on boost factor.
Present and future DM searches with IACT 34
Galactic plane flux sensitivity (CTA)
Moriond Cosmology 2012
― assume Emin = 50 GeV― 500 GeV WIMP annihilating to bb― x10 gain in effective area, x2 gain in hadron rejection― reaches 10-13 cm-2 s-1 sensitivity, except on new sources
~400 hours total
10 hours each bin
Present and future DM searches with IACT 35
Searches for clumps
Moriond Cosmology 2012
HESS sensitivity
― clumps from ViaLacteaII (Diemand, Kuhlen, Madau, 2008)―~104 resolved halos in MW (M>105Msol)― 103 random realizations (rotate the observer position @8.5 kpc)― 168±44 clumps inside HESS galactic survey
Present and future DM searches with IACT 36
Expected <v> limits with clumps (galactic plane)
Moriond Cosmology 2012
Missing one order of mag. to reach thermal <v>
P.Brun, E.Moulin,J.Diemand, J-F.G, PRD 83, 015003 (2011)
Present and future DM searches with IACT 37
Expected <v> limits with clumps (1/4 sky)
Moriond Cosmology 2012
P.Brun, E.Moulin,J.Diemand, J-F.G, PRD 83, 015003 (2011)
― 1/4 survey in ~6 years― assume 5 10-13 cm-2s-1 sensitivity (5 hour/bin)― number of subhalos: 3907±324― thermal WIMPs region reachable
Present and future DM searches with IACT
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Conclusion
− Best constraints on <v> from observation by H.E.S.S of galactic halo
− Many observations of dwarf galaxies. Most stringent constraints from observation of Segue 1 (Magic & Veritas)
− The limits have important astrophysical systematics (GC vs dwarf galaxies, modelling)
− Constraints on DM annihilation in the Fornax cluster (H.E.S.S) competitive with those from dwarf.
− With planned array CTA, observations of Segue1, Willman1 reach the thermal annihilation region with proper boost− Searches for clump with CTA may give detections or
provide stringent constraints.
Moriond Cosmology 2012
Present and future DM searches with IACT
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Back-up slides
Moriond Cosmology 2012
Present and future DM searches with IACT
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Present and future DM searches with IACT
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Present and future DM searches with IACT
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Present and future DM searches with IACT 43
HESS searches towards the Galactic halo
Moriond Cosmology 2012
Present and future DM searches with IACT
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CTA: array design
target performances
Moriond Cosmology 2012
45Present and future DM searches with IACT
Moriond Cosmology 2012
Expectations for Galactic plane survey
― assumes ―x 2 improvement in hadron rejection―x 2 gain in angular resolution ―x 10 gain in effective area
overall increase in sensitivity of ~ 9― expect ~ 300 sources in -30 deg≤ l ≤ 30 deg.
Funk,Hinton,Hermann,Digel, arXiV0901.1885
HESS map of the Gal.plane, total exp ~500 hours
simulated CTA map, flat exposure ~ 5 hours/field