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

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) Also Stellar Interferometry White Paper/RFI (2009)

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 

mas Interferometry in U/B/V Bands?

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

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

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~ % VERITAS at Whipple Observatory 109 m Fall m Since March 2006

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

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

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

Galactic Binary Systems Crab Point source size LSI VERITAS:1 gamma-ray every 8 minutes

<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 

Swift/XRT X-ray: 0.3 – 10 keV Variability of LSI Periodic variation Period: 26.5 days

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

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= cm E λmax =10 eV (~10 14 Hz) At phases BH/NS near star 0.08 AU (r/R g  1) ->    10 At phases BH/NS at 0.7 AU (r/R g  10)   < 1 : VHE gamma rays visible Gupta and Bottecher 2006

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

VERITAS SII Science Extension 8 bit 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

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

VERITAS as an interferometer?

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

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

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

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

CHARA/MIRC Animation

Long-term Future 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 ?

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

CTA imaging capabilities:

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

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

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