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Potential of High Altitude Imaging Air Cherekov Telescope Arrays as Intensity Interferometry Receivers

This paper explores the potential of using high altitude imaging air Cherekov telescope arrays as intensity interferometry receivers for scientific research. The history of intensity interferometry is discussed, as well as the technique and observations of very high energy gamma rays. The paper also discusses the use of large diameter mirrors and the design specifications of the VERITAS telescope array. Potential applications and future developments in intensity interferometry are also explored.

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Potential of High Altitude Imaging Air Cherekov Telescope Arrays as Intensity Interferometry Receivers

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

  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)

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

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

  5. 32 stars measured from Narrabri mV< 2.5 0.41mas < Ø< 3.24mas 10 of them in the main sequence End of operations: 1971

  6. 1963 2006 Later Use of Large Diameter Narrabri Mirrors J.E. Grindlay, 1975 uses the Narrabri telescopes to observe Cen A in gamma TeV energies (Detected by HESS Feb 2009) VERITAS 2009 TeV gamma ray telescopes Use as Intensity Interferometer receivers?

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

  8. Cherenkov radiation images from atmospheric cascades 20 km p p g Atmospheric height 1.4 km m_ m+ e+ e_ 5o

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

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

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

  12. <1 gamma-ray per 3 hours <1 gamma-ray per 15 hours No Observations 26.5 day period 1 gamma-ray every 3 minutes <1 gamma-ray per 15 hours Compact Object /Massive Binary Companion M0 = 15 M ->Unambiguous Identification of Source

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

  14. e- E h e+ -Photon Attenuation Minimum (Threshold) Energy: h =1015 Hz (optical):E> 0.1 TeV h = 1014 Hz (IR) :E> 1 TeV Optical Depth:

  15. Gupta and Bottecher 2006 Companion Star -ray Attenuation BE Star M=15M R=13.5R T=28400º K S=BT4L0=6x1037 erg sec-1 λmax T=0.2897 cm Eλmax=10 eV (~1014 Hz) At phases 0.0- 0.3 BH/NS near star 0.08 AU (r/Rg 1) ->   10 At phases 0.5- 0.8 BH/NS at 0.7 AU (r/Rg 10)  < 1 : VHE gamma rays visible

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

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

  18. Sensitivity? A=100m2 a=30% Df=1GHz T=5 hours S/N=5 n ~ 6.7mV & Dr=14% @ 5mV , Dr=3% This is with just one baseline!!!

  19. VERITAS as an interferometer?

  20. A well-known “b 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

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

  22. First imaging of the 12.9-day eclipsing binary Beta Lyrae CHARA-MIRC Image Model Phase = 0.132

  23. 1.8mas Close Binary star example: Spica 0.53mas 0.22mas Limb and gravity darkening, mutual irradiation tidal distortion non radial oscillation ... b Lyrae VERITAS baselines

  24. CHARA/MIRC Animation

  25. CHARA/MIRC Animation

  26. Long-term Future Should study 100s of sources ! > 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) HAWC 2012 300 GeV – 100 TeV CTA 10 GeV – 300 TeV ? 2015 AGIS 10 GeV – 300 TeV ?

  27. LHASSO SII Implementation 8 bit 500 Mhz Continuous Stream 4GB/s PXIe backplane 10 TB disk 600 Mb/sec =5-10 hours SBA/UBA PMT 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

  28. CTA imaging capabilities:

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

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

  31. Summary • 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 21st century technology • ..$30k/telescope , short development time, easy add-on • Important testbed for future 100 telescope SII system: • ~10 micro-arcsecond resolution

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

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