The Dark Matter Programme of the Cherenkov Telescope Array the CTA Consortium represented by Aldo Morselli INFN Roma Tor Vergata 1
CTA PROJECT Next generation ground based Gamma-ray observatory Open observatory Two sites with more than 0 telescopes Southern Site: Near Paranal, Chile Northern Site: La Palma, Canary Islands, Spain 32 nations, ~300M project +0M manpower 2
CTA sites and example telescope layouts different deployment strategies 3
CTA Headquarters and Science Data Centre decision: 14 June 2016 4
CTA PERFORMANCE Southern Site: 4 Large-size telescopes 25 Medium-size telescopes 70 Small-size telescopes Northern Site: 4 Large-size telescopes 15 Medium-size telescopes s -1 ) -2 x Flux Sensitivity (erg cm 2 E 11 12 13 LAT Pass 8 (y, (l,b)=(0,0)) LAT Pass 8 (y, (l,b)=(120,45)) MAGIC 50 h HAWC 1 year HAWC 5 year H.E.S.S. 50 h Differential flux sensitivity VERITAS 50 h CTA North 50 h CTA South 50 h www.cta-observatory.org (2017-07-05) 2 1 1 Energy E (TeV) R 2 5
Dark Matter EVIDENCE In 1933, the astronomer Zwicky realized that the mass of the luminous matter in the Coma cluster was much smaller than its total mass implied by the motion of cluster member galaxies. Since then, even more evidence: Rotation curves of galaxies Gravitational lensing Bullet cluster Structure formation as deduced from CMB Data by Plank imply: Ω Dm 26.8% Ω M 4.9% 6
Annihilation channels
Dark Matter Search: Targets and Strategies Little or no astrophysical uncertainties, but low sensitivity because of expected small branching ratio 8
Dark Matter Search: Targets and Strategies (Another way to see it) 9
Classical Dwarf spheroidal galaxies: promising targets for DM detection
2015: New DES Dwarf Spheroidal Galaxies Candidates LAT Collaboration DES Collaboration agreement Feb 2015 - first joint paper Search for Gamma-Ray Emission from DES Dwarf Spheroidal Galaxy Candidates with Fermi-LAT Data ApJL 2015, 809,L4,arXiv:1503.02632 DES Year 1 Survey Found 8 new dwarf candidates! analysis of observations of 8 new Dwarf Spheroidal Galaxies found by DES: Bechtol, et al. arxiv:1503.02584 also found by Koposov, et al. arxiv:1503.02079 figure in DES discovery paper 11
Dwarf Spheroidal Galaxies: Growing number of known targets 12
Dwarf Spheroidal Galaxies: CTA Sensitivity Sculptor with SystemaEcs There are several of the newly discovered dsph that have a better case for being a promising target, Will choose most promising targets before observations with the latest knowledge. 13
Dwarf Spheroidal Galaxies: CTA Sensitivity for different Dwarfs. Dashed lines correspond to ±1σ on the J-factors N.B. recent doubts on Segue 1 J-factor due to interlopers in stellar-kinematic samples. V. Bonnivard et al., arxiv: 1506.08209 14
CTA Galactic Halo DM upper-limits τ + τ - W + W - with systemaec uncertainees on the residual cosmic-ray background The predictions shown here can be considered optimistic, even when systematics errors are included, as we do not consider the effect of the Galactic diffuse emission as background for DM searches that can affect the results by ~ 50% This will be investigated in detail in a forthcoming publication by the CTA Consortium.
CTA Galactic Halo DM upper-limits Effect of the different Halo profiles
CTA, Fermi,HESS DM upper-limits Together Fermi and CTA will probe most of the space of WIMP models with thermal relic annihilaeon cross seceon The expectaeon for CTA for the GalacEc Halo is for the Einasto profile and is opemisec as includes only staesecal errors. The effect of the GalacEc diffuse emission can affect the results by ~ 50% As we saw in the previous slides the limits from dwarfs are much less dependent from the systemaec uncertanees s -1 ) 3 v (cm σ 23 24 25 26 27 CTA Sculptor dwarf CTA LMC Fermi HESS Galactic Halo CTA Galactic Halo H.E.S.S. GC halo 254 h W + W - Einasto profile Fermi dsph stacking bƃ CTA Galactic Halo 500 h W + W - Einasto profile CTA Sculptor dwarf 500 h W + W - NFW profile CTA LMC 340 h bƃ NFW profile 0.05 0.1 0.2 1 2 3 4 5 6 20 30 DM mass (TeV)
CTA, HESS, FERMI, PLANK DM upper-limits Together Fermi and CTA will probe most of the space of WIMP models with thermal relic annihilaeon cross seceon The expectaeon for CTA is for the Einasto profile and is opemisec as includes only staesecal errors. The effect of the GalacEc diffuse emission can affect the results by ~ 50% s -1 ) 3 v (cm 23 24 25 WMAP Planck Fermi HESS Galactic Halo σ 26 27 CTA Galactic Halo HESS Galactic halo (254 h) W + W - Einasto profile Fermi dsph stacking (15 dsphs, 5 yrs) bƃ WMAP9 PLANCK CTA Galactic halo, 500 h Einasto, W + W - 0.06 0.1 0.2 1 2 3 4 5 6 20 30 DM mass (TeV)
DM limit improvement estimate in 15 years (2008-2023) CTA GC Halo 500 h Fermi Fermi 15 Years, 45 dwarfs CTA sensitivity curve from Carr et al. 2015 500 hr, statistical only, NFW, 30 GeV threshold arxiv:1508.06128 Together Fermi and CTA will probe most of the space of WIMP models with thermal relic annihilaeon cross seceon
CTA DM DetecEon Strategy First 3 years The principal target is the GalacEc Center Halo (most intense diffuse emission regions removed) Best dsph as cleaner environment for cross-checks and verificaeon (if hint of strong signal) Next 7 years If there is deteceon in GC halo data set (525h) Strong signal: conenue with GC halo in parallel with best dsph to provide robust deteceon Weak signal: focus on GC focus to increase data set unel systemaec errors can be kept under control If no deteceon in GC halo data set Focus observaeon on the best target at that Eme to produce legacy limits. 20
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Perseus cluster Expected CTA sensitivity to the dark matter decay lifetime for 300 h of observation of the Perseus cluster compared with the results from the Galactic Halo by Fermi 22
LMC 340 h of observation CTA sensitivity on from observation of the LMC for 340 hours of observation in the bbar and W + W - annihilation channels for both NFW and isothermal (ISO) dark matter profiles. The sensitivities are computed with a 200 GeV energy threshold assuming statistical errors only 23
Complementarity and Searches for Dark Matter in the pmssm Direct Search LHC CTA Cahill-Rowley et al. arxiv:1305.6921 24
CTA CONTRIBUTION TO DM RESEARCH (SUMMARY) CTA has good prospects to probe for the first Eme WIMP models with thermal relic cross-seceon and masses above 200 GeV; Together with Fermi CTA will be able to exclude thermal WIMPs within the mass range from a few GeV up to a few tens of TeV. For heavy WIMPs (>TeV) CTA will provide unique observaeonal data to probe parameter space not reachable by the other experiments. CTA is complementary instrument to LHC and direct DM searches probing some non-overlapping regions of DM parecle parameter space. If DM is detected by CTA, it will also be possible to explore some properees of DM parecle through the study of annihilaeon channels, etc. Control of systemaecs in deep observaeons of GC halo and dsph(s) is criecal for the success of these studies and will require full knowledge of the instrumentaeon (hence CTA KSP) Beher understanding of J factors is esseneal for interpretaeon of observaeonal data and derivaeon of limits. 25