First Results from VERITAS
description
Transcript of First Results from VERITAS
![Page 1: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/1.jpg)
First Results from VERITAS
David HannaMcGill University Montreal, Canada
![Page 2: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/2.jpg)
Outline of Presentation
- collaboration
- description of the detectortelescopesreadouttriggerconstruction timeline
- 2006-2007 observationsCrab Mrk431, Mrk501LSI+61 3031ES 1218 M87
- near-term planskey science projects
![Page 3: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/3.jpg)
Smithsonian Astrophysical Observatory * Adler Planetarium Purdue University * Barnard College, NY Iowa State University * DePauw University, IN Washington University, St. Louis * Grinnell College, IA University of Chicago * University of California, Santa Cruz
University of Utah * University of Massachussetts University of California, Los Angeles * Cork Institute of Technology McGill University, Montreal * Galway-Mayo Institute of Technology National University of Ireland, Dublin * National University of Ireland, Galway University of Leeds * Argonne National Lab Associate Members
Project office: F.L. Whipple Observatory, SAO
VERITAS CollaborationFour Countries, Six Funding Agencies,
Twenty Institutions, Eighty members
Funding from NSF/DOE/Smithsonian/PPARC/SFI/NSERC
![Page 4: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/4.jpg)
VERITASVery Energetic Radiation Imaging Telescope Array System
four 12 m telescopes located at Whipple Observatory Base Camp
Amado, Arizona
310 40’ N, 1100 57’ W, 1268 masl
![Page 5: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/5.jpg)
Each Telescope
Reflector- 349 hexagonal facets- spherical – 24 m radius- Davies-Cotton mounting- 12 m diameter - 12 m focal length- 110 m2 area
Camera- 499 29mm PMTs- 0.150 separation - 3.50 field-of-view
![Page 6: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/6.jpg)
Camera
PMT
Current monitor
ChargeInjection
Telescope Electronics
500MHzDigitization
64us deepmemory
x
CFD
PatternSensitiveTrigger
Readout140ft
75Ω~200mfiber
Array Control Building
DelaysArray
Trigger
Trigger and Readout
-three-level trigger
1. constant fraction discriminator on each PMT
2. pattern trigger on every telescope (require hits on adjacent PMTs – typically 3)
3. array trigger (require 2 or more telescopes)
- 500 Mega-sample/s Flash ADC on every channel
![Page 7: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/7.jpg)
T4
T3
T2
T1
Prototype
2003 2004 2005 2006 2007 2008
VERITAS Construction History
Observations done with various combinations as they became possible
building running
![Page 8: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/8.jpg)
85 m
109 m
85 m35 m
T4
Fall 2006
January 2007
T4
T2
T3
SinceJanuary
2006
VERITAS-4 at the Whipple Observatory
T1
Base Camp Telescope Layout
![Page 9: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/9.jpg)
![Page 10: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/10.jpg)
Four-telescope event inside the array
![Page 11: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/11.jpg)
Four-telescope event outside the array
![Page 12: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/12.jpg)
Core Reconstruction- 3 telescopes
![Page 13: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/13.jpg)
Core Resolution: 68% Containment
![Page 14: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/14.jpg)
reflected region model
counts
fill all events from the three
background regions into this bin
1
23
stay away from potential source
region
Cra
b ru
n 3
19
65
, wob
ble
off
set 0
.30
background region have same radial distance to
camera center as source region
![Page 15: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/15.jpg)
ring background model
counts
fill all events from this ring into the
bin(acceptance correction!)
Cra
b ru
n 3
19
65
, wob
ble
off
set 0
.30
![Page 16: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/16.jpg)
January 2007` three-telescope data
wobble 76O elevation28.1
Crab Nebula (test pattern)
![Page 17: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/17.jpg)
T1+T2 (Wobble)
T1+T2+T3
2
2
2 distributions:
measure the arrival direction ofthe candidate gamma ray
subtract the coordinates of the source being tracked
square the result 2
cut and subtract background fromthe background regions to get signal
Crab data
![Page 18: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/18.jpg)
Pointing Accuracyfrom Crab Nebula runs
scatter to be reduced with pointing monitors being installed on all telescopes
accuracy degrades as off-axis distance increases
![Page 19: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/19.jpg)
Crab Nebula
30 /√hour
![Page 20: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/20.jpg)
Growth of Crab Signal
![Page 21: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/21.jpg)
VERITAS Performance
effective area: 104 – 105 m2
energy range: 80 GeV – 30 TeV
sensitivity: 10% of Crab Nebula Flux in under one hour (5)
angular resolution: ~ 0.1O - 0.2O (68% containment – E dependent)
energy resolution: ~ 15%
![Page 22: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/22.jpg)
Mrk421: 7.2 hours 5.6 /minute
Mrk501: 11.4 hours 0.8 /minute
AGN Observations:Markarian 421 and Markarian 501Two telescopes: Spring, 2006
good sensitivity to MrK501 in its quiescent state
active state
![Page 23: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/23.jpg)
1ES1218+30.4
2nd furthest VHE blazar (z = 0.182)
detected by MAGICE > 120 GeV8.2 hours6.4
VERITAS detection:observations Dec 06 – Mar 072 or 3 telescopes0.5O wobble17.4 hours after quality cuts10.2 0.3 +/- 0.05 /minute
![Page 24: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/24.jpg)
1ES1218+30.4
VERITAS light curve: no evidence for time variabilitybut statistics are limited
counts per minuteaveraged over the run
(not corrected for elevation angle)
counts per minute daily average
statistical errors only
![Page 25: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/25.jpg)
M87
- giant (elliptical) radio galaxy
- only non-blazar extragalactic VHE source
- 16 Mpc distant – near centre of Virgo cluster
-also called Virgo A- powerful radio source
- core has an AGN with 3.2 x 109 M black hole
- like a BL Lac, but jet does not point at us - jet seen in radio, optical and X-rays with similar morphologies - probably synchrotron radiation -> IC can give VHE - HST says jet angle is <19O (superluminal motion)
- previous detections:HEGRA 4.1 (1998-1999) HESS 13 (2003-2006) variable on different time scales
VLA Radio
Chandra X-ray
HST Optical
![Page 26: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/26.jpg)
51 hours, Feb – Apr 2007 (90% pass quality cuts)
55O – 71O elevation
wobble mode 0.5O
3 telescopes
263 events above background 5.1
threshold energy = 250 GeV
point-like: < 2.3 arc-min radius (ie PSF)
VERITAS observations of M87
cut at = 0.14O
![Page 27: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/27.jpg)
no statistically significant variability observed
day of year 2007
flux (
% o
f C
rab N
ebula
)
M87 light curve
NB: HESS detected day-scale variability during M87 high state in 2005
![Page 28: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/28.jpg)
LSI+61 303
- high mass X-ray binary (HMXB)- one of three detected in TeV rays( HESS detected PSR B1259-63 and LS5039)
- massive Be star with dense circumstellar disk- orbiting a neutron star or black hole
- period = 26.5 days (very similar to lunar cycle – see later)
- close orbit only a few stellar radii separation
- phases (radio defines phase = 0)- periastron 0.23- apastron 0.73- inferior conjunction 0.26- superior conjunction 0.16
- phase-dependent variable emission seen at all wavelengths
MAGIC detection: 54 h, 9.0, E>200 GeV
![Page 29: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/29.jpg)
LSI+61 303 model classes
particle acceleration in both models - VHE rays produced by- inverse-Compton scattering with electrons and stellar photons
and/or- hadronic production of 0s from proton collisions
accretion-powered relativistic jet
relativistic pulsar wind collides with wind from Be star
![Page 30: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/30.jpg)
VERITAS observations of LSI +61 303
Sep - Nov 2006 2 telescopes 32 hours 0.3O wobble
sensitivity: 5 in 3.3 h for 10% of a Crab-like source at 70O
Jan – Feb 2007 3 telescopes 12 hours 0.5O wobble
sensitivity: 5 in 1.2 h for 10% of a Crab-like source at 70O
no data while moon is up
no detection in February but limited observing/statistics
raw rates vs phase
![Page 31: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/31.jpg)
Combined Data
Flux < 3% of Crab in low-flux phase bins,
Flux > 10% of Crab in high-flux phase bin
Period of 26.49 days has 99.94% probability
![Page 32: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/32.jpg)
Can we resolve the source?
2 distribution for high-flux phase bin (0.6 – 0.7) is well fitby Monte Carlo assuming a pointsource
2D sky maps are consistent with point-spread function
PSF
2-telescope data
0.5 < < 0.8 (25 h) 0.8 < < 0.5 (19 h)
LSI +61 303
![Page 33: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/33.jpg)
LSI +61 303
preliminary energy spectrum
Crab-like but 10%
consistent with MAGIC
![Page 34: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/34.jpg)
More Results
results on other topics/sources will be given at the
International Cosmic Ray Conference
Merida, Mexico
July 3 – 11, 2007
![Page 35: First Results from VERITAS](https://reader035.fdocuments.in/reader035/viewer/2022070416/5681502c550346895dbe2005/html5/thumbnails/35.jpg)
Future Plans
near term (first two years):4 key science projects (50%)
- sky survey (Cygnus) 130 hours/year- active galactic nuclei 110 - supernova remnants 100 - dark matter 60
proposed observations (40%)- time allocation committee
director’s discretionary time (10%)- targets of opportunity- engineering
longer term:stay at present site to at least end of 2010