Search Results and Prospects from Atmospheric Cherenkov Telescopes. Andrew W Smith University of Marland, College Park / NASA GSFC

Transcription

1 Search Results and Prospects from Atmospheric Cherenkov Telescopes Andrew W Smith University of Marland, College Park / NASA GSFC

2 From P5 report (Cosmic Frontier) Arrenberg et al. Indirect Detection probes a wide range of theory space in DM

3 In an ideal situation, DM should produce a very recognizable signal in gamma rays

4 Imaging Atmospheric Cherenkov Technique: Primary gamma rays initiate EM showers w particle v>c: Cherenkov pulses HESS (Prague WG) Arrenberg et al.

5 Current TeV Experiments MAGIC-II Canary Islands 2 x 17m HESS-II VERITAS Southern AZ, USA 4x12m Namibia 4x12.5, 1x 28

6 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 ( TeV) in footprint of array Current IACTs can detect (5σ) sources producing 6 ɣ/hr in 25 hrs

7 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

8 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

9 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

10 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

11 Galactic Center Peak of DM profile HESS >300 GeV

12 2011 Abramowski et al. 112 Hours of H.E.S.S. Data

13 254 Hours of H.E.S.S. data 2015 Le Franc et al (ICRC) HESS II

14 VERITAS Galactic Center (> 2 TeV) VERITAS 100 hr estimate VERITAS Observations will constrain multi-tev parameter space

15 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

16 Dwarf Spheroidal Searches Sagittarius HESS MAGIC VERITAS from Drlica-Wagner 2014/ Ackermann et al 2015 and source therein

17 Dwarf Spheroidal Searches All 3 IACTs have accrued ~ hrs Sagittarius on dsphs. from Drlica-Wagner 2014/ Ackermann et al 2015 and source therein

18 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)

19 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)

20 IACT Dwarf Spheroidal Limits VERITAS HESS χ χ -> τ + τ - MAGIC (Einasto) NFW NATURAL CROSS SECTION

21 IACT Dwarf Spheroidal Limits HESS dsph VERITAS MAGIC (EInasto) χ χ -> τ + τ - NFW HESS GC NATURAL CROSS SECTION

22 Limits on χ χ -> ɣ ɣ MAGIC Segue I HESS GC VERITAS dsphs

23 Where can we go from here? MOU in preparation between IACTs to combine data, joint likelihood methods may improve limits on full data set

24 Where can we go from here?

25 CTA Design (S array) Science Optimization under budget constraints Low energies Energy threshold 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)

26 Hinton & Funk arxiv: HESS / VERITAS 100 hrs

27 Hinton & Funk arxiv: HESS / VERITAS 100 hrs

28 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

29 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

30 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