2 Stage et al. 2006 95 Scientists 22 Institutions in 4 Countries Support from: U.S. DOE U.S. NSF Smithsonian STFC (U.K.) NSERC (Canada) SFI (Ireland) U.S.! ! Adler Planetarium! UCLA Argonne Nat. Lab! UCSC Barnard College! U. of Chicago DePauw Univ.! U. of Delaware Grinnell College! U. of Iowa Iowa St. Univ.! U. of Minnesota Purdue Univ.! ! U. of Utah SAO! ! Washington U. Non-Affiliated Members DESY/Potsdam Penn State U.! + 35 Associate Members Theorists, MWL partners, IceCube, Fermi, Swift, etc. VERITAS @ Adler Planetarium, June 2009 Collaboration Mtg. July 2010, Cork, Ireland Ireland! Cork Inst. Tech. Galway-Mayo Inst. N.U.I. Galway Univ. College Dublin Canada! McGill Univ. ! U.K. Leeds Univ.
Performance 3 Detect (5σ) 1% Crab-like source in ~26 hrs. Angular resolution: r68%<0.1o. Energy range: 120 GeV to 30 TeV (Summer 2012 - PMT upgrade with 50% increased QE will lower threshold to ~80 GeV) Energy resolution: ~15% Collection area above 1 TeV: ~ 100,000 m2 Sensitivity Performance Proposed, and first application for funding, in 1998. Phased construction began in Spring 2005. Full array operations began in Autumn 2007. simulation of gamma-ray response
Program For the past 5 years the Whipple 10m telescope has been operated as a dedicated blazar monitor. Program ending this summer and 10m telescope will be decommissioned. 5 Jan. - June 2010
Blazars: ~60% of TeV blazars are variable (most dramatic variability seen in brightest) e.g. Markarian 421 (2010): variability on 5-10 min time scales >10σ per 2 minute bin 6 W. Benbow, “VERITAS Extragalactic Observations”, TeVPA 2010 •Mkn 421: Hot in VHE & X-ray since 11/09 • Season long monitoring + MWL coverage • 35 h of data for season; ~400! • Huge flare on 2/17/10 - Massive MWL camp. • Variability on 5-10 minute time scales •M 87 monitoring -- Multi-year effort • Other VHE, radio & Chandra partners • April 8-11: Massive flaring episode • April 9: VHE flux 2-3x historical high; • Averaged ~20% Crab • Triggered Chandra observations of Core / HST-1 • By far, best VHE signal / spectrum ever PR ELIM IN A RY Friday, July 16, 2010 m VHE AGN PR ELIM IN A RY Large flares → trigger multiwavelength campaigns: Correlated variability / Broadband spectra: Emission models (e.g. SSC, EIC, Proton) Temporal studies: constrain emission region, Quantum Gravity constraints. Spectral studies - statistics at high energies (>10 TeV): EBL absorption, Models Huge flares are rare: monitoring is time-consuming!
8 ] -1 s -2 cm -12 [10 VHE ! 0 10 20 VHE instruments VERITAS MAGIC H.E.S.S. ] -1 s -2 cm -12 [10 VHE ! 0 10 20 Time 29 Jan 05 Feb 12 Feb A [keV/s] X-ray ! 0 2 4 Chandra (2-10 keV) knot HST-1 nucleus B [Jy] radio ! 0.5 1 1.5 2 Time 02 Apr 2007 02 Jul 2007 01 Oct 2007 01 Jan 2008 01 Apr 2008 [Jy] radio ! 0.5 1 1.5 2 VLBA (43 GHz) nucleus (r = 1.2 mas) peak flux density jet w/o nucleus (1.2-5.3 mas) C Science, 325, 444 (2009) (Science, 325, 444, 2009) Multi-wavelength monitoring (VERITAS, HESS, MAGIC, VLBA + Chandra) Constrain location of TeV emission to close to central black hole and not from features in the jet:
I +61 303 9 Compact object orbiting an B0Ve companion (12M⊙) 26.5 day, inclined orbit, e=0.54, circumstellar disk Whipple upper limits only, detected by MAGIC, then VERITAS (8.4σ, Γ=2.4± 0.16stat ± 0.2sys). Strong emission only detected near apastron (ϕ=0.5-0.8) Detected by Fermi-LAT (BSL) Orbital modulation well measured. Emission peaks near periastron Cut-off at 6 GeV observed between LAT and TeV (but not contemporaneous data) No detection by VERITAS during initial Fermi observations 2010: March - November: Fermi detected increased flux and no orbital modulation December: VERITAS detects near Periastron (Atel #2948)
June 2011 VERITAS Transients: HESS J0632 10 Prelim inary VERITAS Feb-Mar 2010 Hinton ApJL 690 (2009) One of few unidentified TeV source in Galactic plane that is point-like, flux 3% Crab (HESS) MWL follow-up shows a hard spectrum X-ray source & faint radio source coincident with a massive B0pe star (MWC148). Located in Rosette Nebula and Monoceros loop (young stellar cluster/molecular cloud complex and SNR,1.4-1.6 kpc) VERITAS non-detection 2006-2009, VERITAS detection in 2010. Variable X-ray emission measured by Swift Binary system? Coincident with MWC 148? More data needed! Recent Development: High X ray and TeV state - ATELs #3152 (Swift) & #3153 (VERITAS) Feb. 2011. Indication of 320-day period, possibly orbital modulation? Swift (Bongiorno et al 2011)
Be star and X-ray pulsar Giant X-ray outbursts about every 5 years (October 1980, June 1983, March/April 1989, February 1994, May/June 2005) VHE emission maximum expected 10-20 days after X-ray flare (Orellana & Romero 2004). Dec. 2009: ToO triggered VERITAS. MJD 55150 55200 55250 /s] 2 Daily Swift-BAT Rate (15-50 keV) [cts/cm 0 0.2 0.4 0.6 0.8 1 1.2 2010 VERITAS Observations: Good coverage: 5-8 hrs in each bin, Zenith angle ~ 20° No TeV emission detected 99% Flux UL > 300 GeV: 0.5 - 2% of Crab
~800 hours per year quality dark time +150 hours of moonlight observations. Summer monsoons - shutdown July & August each year: very competitive for summer (galactic) sources 16:00-22:00 hrs TAC 2010-2011: 1,800 hrs + 350 hrs ToO requested! VERITAS typical breakdown of nominal observing time allocation in previous years: 12 150hrs 150hrs 50hrs 370hrs 80hrs Galactic KSP Blazar KSP Dark Matter KSP General TAC + ToO Spokeperson’s Discretionary Time
template based on existing VERITAS MoUs: VERITAS and Collaboration X agree to conduct coordinated observations on sources of mutual interest, through the exchange of alerts of transient activity. In the case of enhanced activity of a source detected by Collaboration X, VERITAS will be notified and: VERITAS will make a best effort to observe the target, taking into account the observing schedule and competing constraints, and will inform Collaboration X of the results. If observations are made, the VERITAS team will inform Collaboration X of the results of the observations prior to making them public with sufficient time to agree on a joint result. Rapid follow‐up observations can also be accomplished through the use of the VERITAS Spokesperson’s Discretionary time allocation. In the case of enhanced activity from a source detected by VERITAS, Collaboration X will be informed and: Collaboration X’s commitment to follow up..... 13 ctd. over
template based on existing VERITAS MoUs ctd: The sources and source categories, thresholds, etc will be agreed through discussion, and proposals to the VERITAS Time Allocation Committee (and Collaboration X’s .......) Any shared information that is not public (from either group) will be treated in confidence by both collaborations. Group members will be cautioned not to share these results outside of the collaboration in any form, including publications, web sites, e‐mail, ATELs or seminars. This agreement does not prevent either collaboration publishing their own data independently; however, if both collaborations agree that the scientific impact of the results would be enhanced by a joint publication, then authorship will be open to all members of both collaborations. 14
changes / enhancements: Number of alerts be limited to some number each? Some number of alerts be open (i.e. any source class, subject to competing obs. in VERITAS). Joint monitoring of sources? Next Steps: VERITAS Collaboration Meeting in Montreal next week. I will bring suggestions from this meeting to the VERITAS Science Board for further discussion. Any new agreement between VERITAS and another experiment must be approved by the VERITAS Science Board. 15
!"# • 5&6 /101 • 6&% /101 )*+, Birr Castle #"$%&'(('&)"$*#+,%-" !"#$%&'()*+, !"#$%&"'()*+,,)#-./01)2131.41 5&6%"78())!9:-/+94)9;)<=>3)!1?+-/@-4 /101.:9A1)+4)<>BB. 6&%C()&D1-0)09:-/+94);9,)!"E$7),-D+9 /101.:9A1 Birr Castle !"#$%&'()*+, Irish consortium looking to join Lofar Proposed site:Birr Castle Demense, home of the 1.8m Leviathan telescope in the 1800s Work underway to try to secure funding from a variety of sources.
20 MeV - 300 GeV Aeff ~ 0.8 m2 Figure 3.11: Cherenkov light pool on the ground (left). The image of the show as seen by four telescopes in an array (upper right). The four shower imag
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