Results from VERITAS

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Results from VERITAS
Philip Kaaret for the VERITAS Collaboration
(U. Iowa)

• VERITAS characteristics and performance
• Extragalactic astrophysics
• Galactic astrophysics
• Dark matter in dwarf elliptical galaxies
• Searching for the Auger sources

Slides from Ong, Celik, Weekes, Maier, Holder,
Horan, Wood.
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Atmospheric Cherenkov Technique
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Types of events
Hadron
Gamma ray
Muon Ring
Sky Noise
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First proposal
(Weekes, NASA Workshop, Baton Rouge, 1984)
Original proposal for an array of atmospheric
Cherenkov imaging telescopes was made by Weekes
in 1984. The array was to be 7 imaging
telescopes of 10-15 m aperture with 75 m spacing
at an altitude of 3.5 km.
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Very Energetic Radiation Imaging Telescope Array
System
3/2007
1/2006
11/2006
U.S. Canada Ireland Adler
Planetarium Univ. of California, Los Angeles
McGill Univ. Cork Inst. Tech. Argonne
National Lab Univ. of California, Santa
Cruz Galway-Mayo Inst. Tech. Barnard College
Univ. of Chicago U.K. Nat.
Univ. Ireland, Galway DePauw Univ. Univ. of
Delaware Leeds Univ. Univ.
College Dublin Grinnell College Univ. of
Iowa Iowa State Univ. Univ. of
Massachusetts Purdue Univ. Univ.
of Utah 25 Associate
Members Smithsonian
Washington Univ., St. Louis
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A VERITAS Telescope
Camera 499 1 PMTs
FADC 500 MS/s
12m reflector
Site on Mt. Hopkins, AZ (1.3 km)
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VERITAS Performance
Crab Nebula Standard Candle
Effective Area 104 m2 _at_ 100 GeV
105 m2 _at_ 1-50 TeV
1 Crab 90 s (5s) 0.10 Crab 1 hr
0.03 Crab 10 hrs
Sensitivity
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VERITAS Performance
Angular resolution 3-6
Energy resolution 15
Image of the point-like Crab nebula Crab
nebula spectrum (Celik et al.)
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VERITAS Science Program

• Blazars
• BH jet production, Extragalactic background light
  
• Extragalactic Sources
• Non-blazar jets, CR in external galaxies
• Gamma Ray Bursts
• Galactic Compact Objects
• NS/BH binaries, Massive star winds
• Pulsar Wind Nebulae
• Particle acceleration, NS properties
• Supernova Remnants, Galactic Diffuse
• Cosmic ray acceleration, Distribution in Milky
  Way
• Dark Matter
• Astroparticle Physics
• Lorentz violations, UHECR origin
• Unidentified sources

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VHE Sky as seen by VERITAS (Spring 2008)
1ES 1218304 W Comae
Mrk 421
Mrk 501
M87
1ES 0806524
LSI 61 303
IC 443
Crab Nebula
Cas A
1ES 2344514
(From Rene Ong)
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VERITAS Science Highlights

• 2006
• Jul Detection of Crab Nebula and blazars Mrk
  421 and Mrk 501
• 2007
• Mar Detection of XRB LSI 61 303 and
  confirmation of g-ray variability
• Apr Co-Discovery of SNR IC443
• Jul Detection of blazar 1ES1218304, 2nd
  most distant VHE source
• Detection of M87, only non-blazar
  extragalactic VHE source
• 2008 NEW STUFF !
• Jan Detection of blazar 1ES 2344514, TeV
  flare correlated with X-ray
• Mar Discovery of blazar 1ES 0806524 (ATEL
  1415)
• Discovery of blazar W Comae (ATEL
  1422)
• Apr Detection of SNR Cas-A
• M87 Evidence for day-scale
  variability, correlated with X-ray flare
• IC443 Measurement of source
  extension
• May 10 Crab flare from Mkn 421 (ATEL 1506)

NB a VERITAS Detection is gt5s post-trials
significance in two independent analyses.
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Blazar W Comae (and 1ES 1218 304 !)
1ES 1218 Spectrum 9 Crab, steeper
1ES 1218 304 High-Freq. Peaked BL Lac (HBL) z
0.182, one of the most distant VHE sources.
W Comae Light Curve Strong flare 18 Mar 08.
W Comae (ON 231) Low-Freq. Peaked BL Lac
(LBL) Z 0.102, one of only two VHE LBLs known.
(Fortin et al)
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M87
Chandra Light Curves
(Hui et al.)
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X-ray binary LS I 61 303
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SNR IC 443
Gamma-ray Observations
VERITAS Observations

• 34 hrs data (2007).
• 8.25s excess, 0.19 /- 0.02 g/min.
• Flux (gt200 GeV) 3 Crab.
• Extension measured s 0.13o /- 0.02o /-
  0.04o.
• VERITAS position consistent with MAGIC, cloud.

Age 30 kyr, distnace 1.5 kpc. Shell
molecular cloud interaction. HE emission centered
on remnant (EGRET). VHE emission centered on
cloud (MAGIC).
Have also detected Cas A at 3 Crab (9.8
sigma). Working on spectrum
(Humensky et al.)
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Searching for dark matter in dwarf ellipticals

• Weakly interacting massive particles (WIMPs) of
  mass 50 GeV 10 TeV are a candidate for dark
  matter and should produce GeV-TeV gamma-rays as
  secondary products of self-annihilation
• Signal
• Best candidates are dwarf elliptical galaxies
  high M/L, central density peak, best constrained
  DM profile, low astrophysical background
• VERITAS observed Draco, Ursa Minor, Willman I
  for 15-20 hours each
• No signal detected, upper limits of 1-2 Crab

Willman I
(Wood et al.)
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Searching for dark matter in dwarf ellipticals
From Wood et al. 2008. NFW models for Willman I
and Ursa Minor taken from Strigari et al. 2007
(arXiv0709.1510)?
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Auger Sources
Auger reports a correlation of UHECRs (E gt
57?1018 eV) with a catalog of nearby AGN (d lt 75
Mpc) that trace nearby large scale
structure. Identification of sources (AGN or
other?) would be of interest. Photons should be
produced by the UHECRs or sources
directly. VERTIAS searched for TeV emission from
pairs of Auger events.
7 events with declination gt -10o 4 of these
overlap in two pairs
(Holder, Maier 2008)
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Results for Pair B 3 AGN with z lt 0.018
Upper limits (99 confidence, E gt 500 GeV, 608
min of observations) NGC 1358 lt 1 Crab SDSS
J03302-0532 lt 1 Crab SDSS J03349-0548 lt 1
Crab
(Holder, Maier 2008)
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Conclusions

• VERITAS is now operating well and producing
  excellent science.
• The science program includes a variety of
  Galactic and extragalactic objects, a number of
  which are relevant for key questions in
  astrophysics and astroparticle physics.
• Future plans include Galactic plane survey
  (underway), improved energy spectra, and improved
  source localization.
• VERITAS will continue with a broad observing
  program, the best should be yet to come

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VERITAS Galactic Plane Survey

• 2 year program survey of Cygnus region ( -1 lt
  b lt 4 and 52 lt l lt 82 )
• Many targets of interest (SNRS, PWN,
  EGRET/Milagro sources, XRBs )
• Discovery potential

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VERITAS Detections and HEAD papers
Source Type Redshift HEAD Paper Comments
Crab Nebula PWN (Celik, 12.09)
p Standard Candle LSI 61 303 XRB
(Maier,10.12) p 26.5d periodicity IC 443
SNR (Humensky,38.05) VERITAS
co-discovery Cas-A SNR
(Ergin,31.08) p Galactic Sources (Konopelko,38
.02) M87 FR I 0.004 (Hui, 26.25) p Markarian
421 BL Lac 0.030 (Reyes, 20.06) 1st Extragalactic
VHE Source Markarian 501 BL Lac 0.034 (Kildea,
41.01) p Whipple 10m 1ES 2344514 BL
Lac 0.102 (Horan, 20.05) W Comae BL
Lac 0.102 (Fortin, 26.24) p VERITAS discovery 1ES
0806524 BL Lac 0.138 (Fortin, 26.24) p VERITAS
discovery 1ES 1218304 BL Lac 0.182 (Fortin,
26.24) p 2nd most distant VHE source Dark
Matter limits DSph galaxies (Wood, 18.06)
Galactic
Extragalactic