Search Results and Prospects from Atmospheric Cherenkov Telescopes Andrew W Smith University of Marland, College Park / NASA GSFC
From P5 report (Cosmic Frontier) Arrenberg et al. Indirect Detection probes a wide range of theory space in DM
In an ideal situation, DM should produce a very recognizable signal in gamma rays
Imaging Atmospheric Cherenkov Technique: Primary gamma rays initiate EM showers w particle v>c: Cherenkov pulses HESS (Prague WG) Arrenberg et al.
Current TeV Experiments MAGIC-II Canary Islands 2 x 17m HESS-II VERITAS Southern AZ, USA 4x12m Namibia 4x12.5, 1x 28
Rough Performance Values for Current Generation IACTs * Energy range: ~80 GeV to >30 TeV * Energy resolution: 15% at 1 TeV * observation time per year: ~1200 Instrumental PSF hours * point source sensitivity: 1% Crab in <30h, 10% in <30 min = ~600 ɣ/hr (0.1-50 TeV) in footprint of array Current IACTs can detect (5σ) sources producing 6 ɣ/hr in 25 hrs
Indirect Detection of DM w/iacts Assume all the γs you didnt see is this: Constrain this Choose some ppp model to tell you what you should have seen Find an real astronomer to model this for you σv Constraint s= Discrete SUSY parameter scan results. Above curve = disallowed model Mχ
Indirect Detection of DM w/iacts This term is very sensitive to fluctuations in methods What have we learned about this equation? progress? Significant progress σv Constraint s= Discrete SUSY parameter scan results. Above curve = disallowed model Mχ
IACT DM Targets Target Advantages Disadvantages Galactic Center Close by, lots of DM Large γ BG Galactic Substructure Galaxy Clusters Dwarf Galaxies Possibly local, Fermi- LAT sources -Largest DM concentrations in universe -High Mass/Light -No likely γ BG Unknown distance, nature -very distant (weak signal) -very extended -possible γ BG DM distribution can be very uncertain
IACT DM Targets Target Advantages Disadvantages Galactic Center Close by, lots of DM Large γ BG Galactic Substructure Galaxy Clusters Dwarf Galaxies Possibly local, Fermi- LAT sources -Largest DM concentrations in universe -High Mass/Light -No likely γ BG Unknown distance, nature -very distant (weak signal) -very extended -possible γ BG DM distribution can be very uncertain
Galactic Center Peak of DM profile HESS >300 GeV
2011 Abramowski et al. 112 Hours of H.E.S.S. Data
254 Hours of H.E.S.S. data 2015 Le Franc et al (ICRC) HESS II
VERITAS Galactic Center (> 2 TeV) VERITAS 100 hr estimate VERITAS Observations will constrain multi-tev parameter space
Dwarf Spheroidal Searches J ~ (DM density profile) 2 along line of sight Sagittarius NFW Profile, 0.50 integration radius from Drlica-Wagner 2014/ Ackermann et al 2015 and source therein
Dwarf Spheroidal Searches Sagittarius HESS MAGIC VERITAS from Drlica-Wagner 2014/ Ackermann et al 2015 and source therein
Dwarf Spheroidal Searches All 3 IACTs have accrued ~150-200 hrs Sagittarius on dsphs. from Drlica-Wagner 2014/ Ackermann et al 2015 and source therein
MAGIC (165 hrs on Segue I) (Aleksic et al 2015) VERITAS 215 hours on 4 dsphs Zitzer et al 2015) HESS Combined Limits: 140 hours on 5 targets (Abramowski et al 2014)
Aleksic et al 2014 MAGIC (165 hrs on Segue I) (Aleksic et al 2015) VERITAS 215 hours on 4 dsphs Zitzer et al 2015) Likelihood methods improve limits by 2-3 HESS Combined Limits: 140 hours on 5 targets (Abramowski et al 2014)
IACT Dwarf Spheroidal Limits VERITAS HESS χ χ -> τ + τ - MAGIC (Einasto) NFW NATURAL CROSS SECTION
IACT Dwarf Spheroidal Limits HESS dsph VERITAS MAGIC (EInasto) χ χ -> τ + τ - NFW HESS GC NATURAL CROSS SECTION
Limits on χ χ -> ɣ ɣ MAGIC Segue I HESS GC VERITAS dsphs
Where can we go from here? MOU in preparation between IACTs to combine data, joint likelihood methods may improve limits on full data set
Where can we go from here?
CTA Design (S array) Science Optimization under budget constraints Low energies Energy threshold 20-30 GeV 23 m diameter 4 telescopes (LST s) Medium energies 100 GeV 10 TeV 9.5 to 12 m diameter 25 single-mirror telescopes up to 24 dual-mirror telescopes (MST s/scts) High energies 10 km 2 area at few TeV 3 to 4m diameter 70 telescopes (SST s)
Hinton & Funk arxiv:1205.0832 HESS / VERITAS 100 hrs
Hinton & Funk arxiv:1205.0832 HESS / VERITAS 100 hrs
Galactic Plane Survey Fermi bubbles 300 h In the first 3 years of observations, CTA will observe the 300 h 525 h Galactic Plane Survey GC for >500 hours
CTA GC Limits Silverwood, et al., JCAP 03, 055 (2015) Lefranc, et al., PRD 91, 12 (2015) Thermal DM CTA consortium, in preparation CTA will probe deep into natural cross section within 3 years of operation
Summary -Current Generation of IACTs have developed and executed a multi-year DM search program (still in progress) -These programs (significant) have set deep limits, although still mostly separate from the natural cross section. Progress on combining limits. -These programs have paved the way for upcoming searches with CTA, this search will probe deep into the natural cross section within the first few years of operation