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Results from Galactic Source Observations with VERITAS

Results from Galactic Source Observations with VERITAS. Amanda Weinstein for the VERITAS Collaboration Moriond, Feb. 4, 2009. Outline. Introduction to VERITAS VERITAS Galactic Science Program Overview Highlight results Summary and future prospects. VERITAS at Whipple Observatory.

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Results from Galactic Source Observations with VERITAS

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  1. Results from Galactic Source Observations with VERITAS Amanda Weinstein for the VERITAS Collaboration Moriond, Feb. 4, 2009

  2. Outline • Introduction to VERITAS • VERITAS Galactic Science Program • Overview • Highlight results • Summary and future prospects

  3. VERITAS at Whipple Observatory Data, October 2007-June 2008: ● Good weather, 4-telescopes ~800 hours ● Moonlight ~100hrs → ~35% moonlight data this fall Since March 2006 T2 109 m Fall 2006 85 m T3 82 m 35 m T4 T1 April 2007 ● FLWO,Mt. Hopkins, Az (1268 m asl) Specifications: ● Angular resolution ~ 0.1° ● Energy resolution ~ 15-20 % Sensitivity: ● 1% Crab @ 5 s ~ 47 hrs ● 5% Crab @ 5 s ~ 2.5 hrs

  4. VERITAS Galactic Science Program Dark accelerators… Unidentified Objects SNR/PWN Key Science Project Composite and shell-type SNR Strategy: search for TeV PWN associated with pulsars E/d2 > 1x1035 ergs/s/kpc2 Cygnus Region Sky Survey (Key Science Project) e.g. HMXBs, LMXBs, magnetars (microquasars) Combination of dedicated and serendipitous observations (objects in FOV of other targets, survey) Galactic Compact Objects

  5. Crab Galactic Science LSI 61+303 MGRO J1908+06 IC443 AGILE 2021+4024 Geminga PSR J1740+1000 PSR J0631+1036 PSR J0205+6449 Cas A

  6. Young (330yrs) SNR at a distance of ~3.4 kpc Massive star progenitor 5’ (4.5 pc) diameter (comparable to TeV angular resolution) Discovered in TeV by HEGRA (232 hrs, 5 s), confirmed by MAGIC (47 hrs, 5.3 s) Flux ~ 3.3 % Crab above 1 TeV Power-law index of 2.3 ± 0.2stat ± 0.2sys Well studied SNR in a relatively clean environment Extensive modeling of cosmic-ray acceleration and gamma-ray production exists Cas A • VERITAS: wobble-mode observations, 0.5º offset, during Oct/Nov 2007 with 4 telescopes • Exposure: 20.3 hr: 9.8 s detection • Flux: ~ 3% Crab • Consistent with a point source

  7. Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime: Feb / Mar 2007 with 3 telescopes, PWN location Oct / Nov 2007 with 4 telescopes Center of Feb/Mar hot spot: 06 16.9 +22 33 Flux ~3% Crab 8.2σ peak significance pre-trials IC 443 • Middle-aged SNR ~ few – 10 kyr • SNR shell / molecular cloud interaction (beam dump) • PWN (southern edge): spin-down luminosity uncertain (1036 erg/s – 5 x 1037 erg/s) • Co-discovered (MAGIC/VERITAS) in TeV in 2007 • Green – Radio • Red – Optical • Blue – X-rays PRELIMINARY VERITAS position PWN

  8. IC 443 • 2-D Gaussian profile fit • Centroid: 06 16.9 +22 32.4 ± 0.03º(stat) ± 0.07º(syst) • Extension: σ ~ 0.17º ± 0.02º(stat) ± 0.04º(syst) • Not coincident w/radio/optical shell to northeast • Overlap with CO indicating molecular cloud along line of sight • Maser emission suggests SNR shock interacting with cloud • TeV emission could be • CR-induced pion production in cloud(1,2) • associated with the pulsar wind nebula to the south (relic electrons?)(3) • Zhang, L. and Fang, J. Ap. J. 675 L21 (2008). • Torres, D. F. et al. arXiv:0804.2526. • (3) Bartko, H. and Bednarek, W. arXiv:0712.2964. Elongation along cloud

  9. LSI 61+303 J.Casares et al (MNRAS 360, 1105 (2005)) MW: Fermi ~25hrs ~21hrs ~45hrs 50% moonlight data MW: Swift/RXTE VERITAS: phases 0.2-0.9 MW: Swift, RXTE Microquasar? Binary pulsar?

  10. LSI+61 303: 2006-2008 RXTE(2-10keV) 2007-2008 2006-2007 SWIFT(0.2-10keV) 8.4σ detection 7.3σ detection

  11. LSI+61 303: 2006-2008 2007-2008 Consistent with 2006-2007 spectrum 2006-2007 only Consistent with MAGIC • Γ=2.40± 0.16 (stat) ±0.2 (sys) • Γ=2.6± 0.6 (stat) ±0.2 (sys) Phase-resolved (0.5-0.8)

  12. LSI 61+303 2008-2009 2007-2008 2006-2007 apastron PRELIMINARY 4.5σ detection 8.4σ detection No strong excess (2.6σ) periastron PRELIMINARY 3.6σ pre-trials Strong indication of orbit-to-orbit variability

  13. Nov 2008 In Context Fermi data (Dubois, AAS, 2009) Nov. 2008 data part of a MWL campaign: detects the source continuously Emission peaks at periastron PRELIMINARY orbit-orbit variability(?) Sees clear periodicity VERITAS data: 99% upper flux limit: F(E>500 GeV)< 1.26x10-12 cm-2s-1 (2.1% Crab) ? Apastron, 2006-2007

  14. VERITAS Sky Survey • Partial survey of Cygnus region • -1 < b < 4 and 67 < l < 82 • Completed this fall (along with a small/moderate amount of followup) • At least 6 hrs acceptance-corrected exposure at each point in the survey • Survey analysis ongoing (release pending additional observations in April)

  15. VERITAS Data taken under aegis of sky survey ~22h of 4-telescope data 4.85σ detection ~0.19°± 0.04° extension position in agreement with HESS J1908+063 MGROJ1908+06 / HESS J1908+063 • Needed a test case for Sky Survey extended source search, chose MGRO J1908+06/HESS J1908+063 • MGRO unidentified source • 80% of Crab Nebula Flux, <2.6° diam. extension at 20 TeV • Detected in HESS galactic plane survey • 14% Crab flux > 300 GeV • Source extension 0.21°± 0.07° (stat) ±0.05°(sys) PRELIMINARY Significance Map (smoothed)

  16. AGILE 2021+4024 • Observations (initially under moonlight) triggered by AGILE atels • 7 hour exposure • 99% upper limit at 2% Crab flux above 300 GeV.

  17. A new guide: Future prospects • new Fermi pulsars, or sources w/PWNe associations → PWN searches, searches for pulsed emission from gamma-ray loud pulsars (if cutoff is favorable), new Fermi XRBs • GeV-TeV connection → disentangling nature of object, emission (e.g LSI, IC443…) • Coordinated GeV-TeV observations

  18. Summary • VERITAS Galactic science program in first 2 years has been fruitful • SNR/PWN detections: Crab, CasA, IC443 • UnID detections: MGRO J1908+06/HESS J1908+063 • Long-term observations (+MWL) of LSI 61+303 have contained some suprises • Expect: updated analyses of SNR detections (Cas A, IC443) • Expect a number of new results by summer, including the Sky Survey • Moving T1 will improve our sensitivity to galactic sources • Fermi data and VERITAS Sky Survey results will likely modify our observing strategy for the coming year

  19. EXTRA/ BACKUP

  20. The Crab: A Standard Candle 5σ Detection Sensitivity 1% Crab in 47 hours 5% Crab in 2.5 hours Measured sensitivity to the Crab Nebula at high elevation (>65°) HESS ~1% Crab in 25 hours (but mirror reflectivity now degraded) MAGIC ~2% Crab in 50 hours

  21. Geminga • VERITAS Observations: 13.3 hours at high elevation • Upper Limit to steady emission(>300 GeV): <2x10-8 γ/m2/s (~1% Crab flux) • Upper Limit to pulsed emission(>300 GeV): <1x10-8 γ/m2/s (~0.5% of Crab flux)

  22. IC443 IC443 • Green – Radio • Red – Optical • Blue – X-rays

  23. Observed (wobble, 0.5º offset) during two epochs, for 37.1 hrs total livetime: Feb / Mar 2007 with 3 telescopes, PWN location Oct / Nov 2007 with 4 telescopes Center of Feb/Mar hot spot: 06 16.9 +22 33 Flux ~3% Crab 8.2σ peak significance pre-trials IC 443 • Middle-aged SNR ~ few – 10 kyr • SNR shell / molecular cloud interaction (beam dump) • PWN (southern edge): spin-down luminosity uncertain (1036 erg/s – 5 x 10 1037 erg/s) • Co-discovered (MAGIC/VERITAS) in TeV in 2007 PRELIMINARY PWN

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