1. Dave Kieda & Stephan LeBohec University of Utah Department of Physics and Astronomy John Davis University of Sydney, NSW Science Potential of High Altitude Imaging Air Cherekov Telescope Arrays as Intensity Interferometry Recievers ה ” בע

2. Outline Part I: What is Intensity Interferometry & History (Thanks to John Davis!) Part II: VHE  -ray Observatories and Technique Part III: Potential science of future joint IACT/II Arrays A Good Online Reference: 2009 Stellar Interferometry Workshop (Salt Lake City, Utah) http://www.physics.utah.edu/~lebohec/SIIWGWS Also Stellar Interferometry White Paper/RFI (2009)

6. Intensity Wave noise Intensity Inteferometry Theory: A Photon Wave Description* *n.b. Full Q.M. photon description gives same correlation equatrion Narrowband filter  As prescribed by van Cittert-Zernike theorem -> S/N independent of 

8. mas Interferometry in U/B/V Bands?

13. 32 stars measured from Narrabri m V < 2.5 0.41mas < Ø< 3.24mas 10 of them in the main sequence End of operations: 1971

14. 1963 J.E. Grindlay, 1975 uses the Narrabri telescopes to observe Cen A in gamma TeV energies (Detected by HESS Feb 2009) 2006 VERITAS 2009 TeV gamma ray telescopes Use as Intensity Interferometer receivers? Later Use of Large Diameter Narrabri Mirrors

15. T1 35 m 82 m April 2007 T4 T2 T3 Instrument design: ● Four 12-m telescopes ● 499-pixel cameras (3.5° FoV) ● FLWO,Mt. Hopkins, AZ (1268 m a.s.l.) ● Completed Spring, 2007 Specifications: ● Energy threshold ~ 150 GeV ● Angular resolution < 0.14° ● Energy resolution~ 10-20 % VERITAS at Whipple Observatory 109 m Fall 2006 85 m Since March 2006

16. Cherenkov radiation images from atmospheric cascades __ Atmospheric height 1.4 km 20 km p  e+e+ e_e_  5o5o p

17. Ground Based Gamma-Ray Astronomy Gamma-Ray detection  ~ 1.5 o 12 m dia. Mirror 499 pixel camera 500 Mhz FADC electronics Gamma-Ray image

18. Individual gamma-rays observed by three independent telescopes 3.5 o Telescope 1 Telescope 3 Telescope 2 Each Frame is 6 nanoseconds

19. Galactic Binary Systems Crab Point source size LSI 61+303 VERITAS:1 gamma-ray every 8 minutes

20. <1 gamma-ray per 3 hours 1 gamma-ray every 3 minutes <1 gamma-ray per 15 hours 26.5 day period No Observations Compact Object /Massive Binary Companion ->Unambiguous Identification of Source M 0 = 15 M 

21. Swift/XRT X-ray: 0.3 – 10 keV Variability of LSI 61+303 Periodic variation Period: 26.5 days

22.  -Photon Attenuation EE h e+e+ e-e- Minimum (Threshold) Energy: h =10 15 Hz (optical): E  > 0.1 TeV h = 10 14 Hz (IR) : E  > 1 TeV Optical Depth:

23. Companion Star  -ray Attenuation BE Star M=15M  R=13.5R  T=28400º K S=  B T 4 L 0 =6x10 37 erg sec -1 λ max T=0.2897 cm E λmax =10 eV (~10 14 Hz) At phases 0.0- 0.3 BH/NS near star 0.08 AU (r/R g  1) ->    10 At phases 0.5- 0.8 BH/NS at 0.7 AU (r/R g  10)   < 1 : VHE gamma rays visible Gupta and Bottecher 2006

24. Intensity Interferometry and Air Cherenkov Arrays HESS 12m telescope array (Namibia) 100m100m 85m85m VERITAS 12m telescope array (Arizona)

25. VERITAS SII Science Extension 8 bit 300-500 Mhz Continuous Stream 4GB/s PXIe backplane 10 TB disk 600 Mb/sec =5-10 hours Cost/telescope: $30 k Total Extension Cost: $135 k Can also do Optical transient with same data stream SBA/UBA PMT

27. Sensitivity? A=100m 2  =30%  f=1GHz T=5 hours S/N=5 n ~ 6.7m V &  r=14% @ 5m V,  r=3% This is with just one baseline!!!

28. VERITAS as an interferometer?

29. A well-known “  Lyrae” system:  Lyrae: interacting and eclipsing binary (period 12.9 days) B6-8 II donor + B gainer in a thick disk H  emission, probably from a jet V = 3.52, H = 3.35; distance ~300pc

30. First imaging of the 12.9-day eclipsing binary Beta Lyrae Baseline coverage

31. Phase = 0.132 First imaging of the 12.9-day eclipsing binary Beta Lyrae ModelCHARA-MIRC Image

32. Close Binary star example: Spica 1.8mas 0.53mas 0.22mas VERITAS baselines Limb and gravity darkening, mutual irradiation tidal distortion non radial oscillation...  Lyrae

33. CHARA/MIRC Animation

38. Long-term Future 2012 2015 AGIS HAWC CTA > Need 2 kinds of instrument: - Large FOV (sky monitoring) - High resolution/  statistics (deep study) > Energy range extension - At low energy ( large mirrors) - At high energy (sq km area) > Improved angular resolution - Large telescope array > Improve sensitivity - Large effective collection area > LHASSO: TeV, SII (U/B/V band) Should study 100s of sources ! 300 GeV – 100 TeV 10 GeV – 300 TeV ?

39. LHASSO SII Implementation 8 bit 500 Mhz Continuous Stream 4GB/s PXIe backplane 10 TB disk 600 Mb/sec =5-10 hours Cost: $30 k * 100 Telescopes = $3M < 2% CTA Data Stream: 200 TB/night = 100 PB/year (dedicated!) more realistically 2 PB/year Need to process data in real time! Can also do Optical transient with same data stream SBA/UBA PMT

40. CTA imaging capabilities:

42. DT ~ 20% Occulting Binaries? With CTA m v =8, |g| 2 =0.5 -> S/N=5 in 5 hours so D|g| 2 ~ 0.1 m v =5.5 -> D|g| 2 ~ 0.01

44. StarBase Utah: Two 3m II telescopes on a 23m baseline at Bonneville Seabase, Grantsville Utah First Light Summer 2009!

45. Intensity Interferometry can make < 1 mas stellar measurements with VERITAS telescopes/optics U/V band stellar imaging possible due to relative insensitivity of II to atmospheric stability Small IACT array could make measurements in U/B/V band with ~0.1 milli-as imaging capability: Unmatched Science 500 Ms/sec -1 Gs/sec continuous streaming for 5 hours now possible: Use 21 st century technology..$30k/telescope, short development time, easy add-on Important testbed for future 100 telescope SII system: ~10 micro-arcsecond resolution Summary

46. http://www.physics.utah.edu/~lebohec/SIIWGWS