Highlights of VERITAS Results M. Schroedter* for the VERITAS - PowerPoint PPT Presentation

Highlights of VERITAS Results M. Schroedter* for the VERITAS Collaboration # * Iowa State University, # http://veritas.sao.arizona.edu

VERITAS Collaboration VERITAS @ Adler Planetarium, June 2009 ~ 100 Scientists 22 Institutions in 4 Countries Support from: Smithsonian Inst. U.S. NSF U.S. DOE STFC (U.K.) NSERC (Canada) SFI (Ireland) Stage et al. 2006 U.S. Canada Ireland Adler Planetarium Purdue Univ. Univ. of Iowa McGill Univ. Cork Inst. Tech. Argonne Nat. Lab SAO Univ. of Massachusetts Galway-Mayo Inst. U.K. Barnard College UCLA Univ. of Utah N.U.I. Galway DePauw Univ. UCSC Washington Univ. Univ. College Dublin Leeds Univ. Grinnell College Univ. of Chicago + 25 Associate Members Iowa St. Univ. Univ. of Delaware ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Outline  Technique  VERITAS Telescope Array • Layout, technical details, performance  Science Highlights • Extragalactic • Discovery of Starburst Galaxy M82 • Radio Galaxy M87 • Galactic Sources • Boomerang • Dark Matter Searches Stage et al. 2006  VERITAS Upgrade Plans ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Atmospheric-Cherenkov Technique Upper atmosphere 1 TeV γ -ray produces z(m) relativistic particle shower ~2 o Cherenkov 8 km wavefront 1 m (3 ns) thick 1 3 x(m) 120 m 2 Sky y( o ) view 3 1 Detection area: 50,000 m 2 Scale larger than football field! Energy: 0.1-50 TeV well reconstructed 2 Energy resolution: ~18% source location x( o ) Angular res.: <0.12 o

New VERITAS Telescope Array T3 Fall 2006 81 m 126 m T4 Spring 2007 Whipple 10m T1-new Fall 2009 101 m 99 m N T2 Spring 2006 ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Technical Details Cosmic-ray event PMT Assembly Camera (x 4) 499 PMTs, 3.5 o FOV FADC Readout 500 Msps, dual-gain Stage et al. 2006 3-Level Trigger Telescope (x 4) Pixel, Telescope, Array Mirror Facets (x 350) 12-m diameter Davies-Cotton Deadtime ~10% @ 250 Hz f 1.0, 110 m 2 area Reflectivity ~ 88% (Recoated every 2 years) ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Old Old VERITAS Performance Effective Area (std. cuts) Canonical Performance Values:  Energy Range: 100 GeV – 30 TeV (spectra >150 GeV)  Energy Resolution: 15% – 20%  Crab Rate ~ 40 / min (trigger)  Sensitivity: 5% Crab in < 2.5 h 1% Crab in < 50 h  Angular Resolution: r 68 < 0.1 o  Pointing Accuracy: < 50 ’’ New: 30% less time! 1% Crab <50 h 5% Crab 2.5 h Stage et al. 2006 Energy Resolution Angular Resolution Pt. Source Sensitivity ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Outline  Technique  VERITAS Telescope Array • Layout, technical details, performance  Science Highlights • Extragalactic • Discovery of Starburst Galaxy M82 • Radio Galaxy M87 • Galactic Sources • Boomerang • Dark Matter Searches Stage et al. 2006  VERITAS Upgrade Plans ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

VERITAS Science Highlights M82 21 Sources 6 Classes Starburst galaxy M87 Black hole - jet Z=0.44

Extragalactic Sources  Active Galactic Nuclei • BH accretion powers relativistic jet & VHE particle acceleration. • Science goals: emission mechanism, jet physics, BH engine. • Sources of UHE cosmic rays? • Double-peaked SED Simultaneous MWL data crucial. a) Blazars (10) • Highly variable emission: 3 min • Probe EBL from spectra via: γ VHE + γ EBL  e + e - b) Radio Galaxies: M87, Cent-A • Closer, so structure can be better resolved.  Starburst Galaxy: M82 ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

M82: Starburst Galaxy  M82: Prototype starburst galaxy M82 • Interacting with group of galaxies over M81 hundreds of Myrs. • Tidal forces  active starburst region (HST shows > 200 massive star clusters. • SMBH < 3 x 10 7 M sun , no AGN activity. Johannes Schedler (Panther Observatory)  Starburst Region • High star formation and SNR rate. M82 • High CR density (from radio emission). • High gas density ~ 150 #/cm 3 • γ -rays from cosmic rays (p + and e - ) interacting with gas and B-field Clues on origin of CR ʼ s. • Previous limits < 10% Crab 0.1-10 keV, Chandra (HEGRA, Whipple). Also limits on NGC 253. ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

M82: Starburst Galaxy  VERITAS Data & Analysis • 2007-09: 137 h live time. Only dark time (no moonlight). • “Hard cuts” from a priori study Excess of Crab data at similar zenith ( θ ~ 40º).  Detection ! • 5.0 σ excess (pre-trials), 4.8 σ (post-trials). Consistent with point source at M82. • Many systematic checks of analysis procedure, background method, and potential biases. (E > 700 GeV) • Among weakest VHE sources ~0.9% Crab.  Interpretation Stage et al. 2006 • First detection of an extragalactic VHE source not clearly associated with AGN activity. “Discovery of Gamma-ray Emission • Consistent with predictions, general nature from a Starburst Galaxy,” of CR interactions. Acciari et al., submitted to Nature. ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

M82: Starburst Galaxy  Energy spectrum • Range: 0.9 to 5 TeV • Well fitted by pure power law Γ = 2.5 ± 0.6stat ± 0.2sys  Hadronic emission p CR + p ambient  π 0  γ γ TeV  π +/-  e, ν e + B-field  radio/IR synchro Measured 32 GHz flux is consistent with VHE γ -ray spectrum extrapolated to 20 GeV if Γ = 2.3 and B~8nT . Model of Persic et al. 2008  Leptonic signature (IC) e CRs + γ IR  e + γ IC Consistent with Chandra 5 keV Pohl (1994), Völk et al. (1996), Persic et al. flux for 1 GeV CR-electrons, 8 nT. (2008), de Cea del Pozo et al. (2009) ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

M87: Radio Galaxy Radio (Very Large Array) Radio map 150 kly Optical (Hubble) VHE resolution ~6000 lyr X-ray (Chandra)  Giant elliptical radio galaxy • Jet angle ~30 o • Super massive BH ~6x10 9 M   17 Mpc (z=0.004)  International multi- λ campaign ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

M87: Radio Galaxy  TeV γ -ray outburst VHE γ -rays • Duration ~ a week • Nucleus active in X-rays, 43 GHz  VLBA resolution at 6R S • Variability confined to nucleus • R S = 44,000 km VERITAS, VLBA, HESS, and MAGIC, Science 325 , July 2009. X-ray HST-1 X-rays Nucleus ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Outline  Technique  VERITAS Telescope Array • Layout, technical details, performance  Science Highlights • Extragalactic • Discovery of Starburst Galaxy M82 • Radio Galaxy M87 • Galactic Sources • Boomerang • Dark Matter Searches Stage et al. 2006  VERITAS Upgrade Plans ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Galactic TeV Sources  Supernova remnants (5) • Shell-type (IC 443, Cassiopeia A) • Pulsar-wind nebulae (Crab, Boomerang, G54.1)  X-ray Binary • LSI +61 303 all VERITAS sources • Be star + compact companion  Galactic plane is rich in  Unidentified γ -ray emission: • MGRO 1908, HESS J1857 • 90% photons seen at GeV energies. • Bright in VHE γ rays • Dark otherwise • Probe acceleration of e, p in shock fronts, colliding winds, superbubbles Extragalactic Hope to pin down CR Origin: Blazars, Radio galaxies need ν -signature! Starburst galaxy ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Boomerang/PSR J2229+6114  Energetic pulsar + wind nebula discovered by EGRET North • Age ~ 10,000 years • Period: ~50 ms • E-dot = 2.2x10 37 erg/s • Distance ~800 pc (Kothes et al.)  Likely associated with large SNR G106.3+27  Fermi-LAT Bright Source list  Emission at ~35 TeV reported by Milagro (Abdo et al., 2009) ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Boomerang/PSR J2229+6114  VERITAS Observations • Observations overlap radio shell • 33 h, 6.0 σ post-trials • Flux ~5% Crab above 1 TeV  TeV emission is extended • Spans a 0.4 o x 0.6 o region • Peak is 0.4 o from pulsar • Overlaps region of high CO density Color map: VERITAS Circle: Fermi error circle Dot: Pulsar position Black: 1.4 GHz DRAO V. A. Acciari et al., sub. to ApJ. Purple lines: CO ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Boomerang/PSR J2229+6114  Energy spectrum • Integrate over 0.32o radius centered on emission peak Milagro • Well fitted by pure power law Γ = 2.3 ± 0.3stat ± 0.3sys,  Extension of spectrum is consistent within errors with Milagro point at 35 TeV  If associated with pulsar Favors hadronic origin of VHE γ ? p CR + p ambient  π 0  γ γ ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter

Outline  Technique  VERITAS Telescope Array • Layout, technical details, performance  Science Highlights • Extragalactic • Discovery of Starburst Galaxy M82 • Radio Galaxy M87 • Galactic Sources • Boomerang • Dark Matter Searches Stage et al. 2006  VERITAS Upgrade Plans ν s and DM, Madison, 2009 Results from VERITAS Martin Schroedter