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Science Potential of High Altitude Imaging Air Cherekov Telescope Arrays as Intensity Interferometry Recievers Dave Kieda & Stephan LeBohec University of Utah Department of Physics and Astronomy John Davis University of Sydney, NSW בע”ה 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) Intensity Inteferometry Theory: A Photon Wave Description* Intensity Wave noise Narrowband filter As prescribed by van Cittert-Zernike theorem -> S/N independent of *n.b. Full Q.M. photon description gives same correlation equatrion mas Interferometry in U/B/V Bands? 32 stars measured from Narrabri mV< 2.5 0.41mas < Ø< 3.24mas 10 of them in the main sequence End of operations: 1971 Later Use of Large Diameter Narrabri Mirrors 1963 2006 J.E. Grindlay, 1975 VERITAS 2009 uses the Narrabri telescopes TeV gamma ray telescopes to observe Cen A in gamma TeV energies Use as Intensity Interferometer receivers? (Detected by HESS Feb 2009) VERITAS at Whipple Observatory T2 109 m Fall 2006 T3 82 m 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 % Since March 85 m2006 35 m T4 April 2007 T1 Cherenkov radiation images from atmospheric cascades 20 km p p Atmospheric height 1.4 km m e+ e 5o _ _ m+ 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 Individual gamma-rays observed by three independent telescopes Telescope 1 Telescope 3 3.5o Each Frame is 6 nanoseconds Telescope 2 Galactic Binary Systems Crab Point source size LSI 61+303 VERITAS:1 gamma-ray every 8 minutes Compact Object /Massive Binary Companion M0 = 15 M 26.5 No Observations day periodevery 1<1 gamma-ray gamma-ray per 315minutes hours hours ->Unambiguous Identification of Source Variability of LSI 61+303 Periodic variation X-ray: 0.3 – 10 keV Swift/XRT Period: 26.5 days -Photon Attenuation e- E h e+ Minimum (Threshold) Energy: h =1015 h = Hz (optical): 1014 Hz (IR) : E > 0.1 TeV E > 1 TeV 2m c E 2 2 e h 1 40 1 13 rn 200 L 10 erg sec 10 Hz r R Optical Depth: T 0 0 g 1 3 Companion Star -ray Attenuation BE Star M=15M R=13.5R T=28400º K S=BT4 L0=6x1037 erg sec-1 λmax T=0.2897 cm Eλmax=10 eV (~1014 Hz) 200L0 1040 erg sec 1 1013 Hz r Rg 1 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 Gupta and Bottecher 2006 Intensity Interferometry and Air Cherenkov Arrays HESS 12m telescope array (Namibia) VERITAS 12m telescope array (Arizona) 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: Total Extension Cost: $30 k $135 k Can also do Optical transient with same data stream Sensitivity? A=100m2 a=30% f=1GHz T=5 hours S/N=5 n ~ 6.7mV & r=14% @ 5mV , r=3% This is with just one baseline!!! VERITAS as an interferometer? A well-known “b Lyrae” system: • b Lyrae: interacting and eclipsing binary (period 12.9 days) • B6-8 II donor + B gainer in a thick disk • Ha emission, probably from a jet • V = 3.52, H = 3.35; distance ~300pc First imaging of the 12.9-day eclipsing binary Beta Lyrae Baseline coverage First imaging of the 12.9-day eclipsing binary Beta Lyrae CHARA-MIRC Image Model Phase = 0.132 Close Binary star example: Spica 0.53mas 0.22mas 1.8mas Limb and gravity darkening, mutual irradiation tidal distortion non radial oscillation b Lyrae ... VERITAS baselines CHARA/MIRC Animation CHARA/MIRC Animation Long-term Future Should study 100s of sources ! HAWC > Need 2 kinds of instrument: 2012 - Large FOV (sky monitoring) - High resolution/ statistics (deep study) 300 GeV – 100 TeV CTA > Energy range extension - At low energy ( large mirrors) - At high energy (sq km area) 2015 > Improved angular resolution 10 GeV – 300 TeV ? AGIS - Large telescope array > Improve sensitivity - Large effective collection area > LHASSO: TeV , SII (U/B/V band) 10 GeV – 300 TeV ? LHASSO SII Implementation 8 bit 500 Mhz Continuous Stream 4GB/s PXIe backplane SBA/UBA PMT Cost: Data Stream: 10 TB disk 600 Mb/sec =5-10 hours $30 k * 100 Telescopes = $3M < 2% CTA 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 CTA imaging capabilities: Occulting Binaries? With CTA mv=8, |g|2=0.5 -> S/N=5 in 5 hours DT ~ 20% so D|g|2 ~ 0.1 mv=5.5 -> D|g|2 ~ 0.01 StarBase Utah: Two 3m II telescopes on a 23m baseline at Bonneville Seabase, Grantsville Utah First Light Summer 2009! 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 http://www.physics.utah.edu/~lebohec/SIIWGWS