Download D.Kieda

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)
   200L0 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