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Jamie Holder and Gernot Maier University of Delaware/ McGill University

A summary of other eventdisplay analysis results from Fall 2006 and some other stuff wot I hav dun. Jamie Holder and Gernot Maier University of Delaware/ McGill University. VERITAS Collaboration Meeting, Tucson, January 2007. Overview. Results for November dark run Some other stuff.

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Jamie Holder and Gernot Maier University of Delaware/ McGill University

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  1. A summary of other eventdisplay analysis results from Fall 2006 and some other stuff wot I hav dun. Jamie Holder and Gernot Maier University of Delaware/ McGill University VERITAS Collaboration Meeting, Tucson, January 2007

  2. Overview • Results for November dark run • Some other stuff

  3. Summary of Observations • All Observations taken during the November dark run • Two-telescope data only • major noise problems resolved • relative gain gradient removed • Loose run selection criteria • Better than B weather • No major hardware problems

  4. Summary of Observations Details of the sources will be presented this afternoon

  5. Analysis • Eventdisplay/mscw_energy/anasum • 5.0/2.5 σ pixel cleaning • doublepass trace analysis • Cleaning Cuts: • Two images with ≥5 pixels • Hillas distance <1.2° • Angle between image axes >10° • Gamma Selection Cuts: • image size > 400 dc in each image • mean-scaled width < 0.5 • mean-scaled length < 0.5 • θ2 < 0.025 (θ<0.158°)

  6. Results: Ring Background • Ring Background Details: • Ring Radius = 0.5° • Ring Width = 0.15°

  7. Results: Reflected Region • Reflected Region Details: • Fixed number of regions • 3 for 0.3° offset • 5 for 0.5° offset

  8. Sky maps: Tycho Reflected Region Background Ring Background

  9. Sky maps: PSR J2021 Reflected Region Background Ring Background

  10. Sky maps: PSR J2229 Reflected Region Background Ring Background

  11. Sky maps: 1ES 0806 Reflected Region Background Ring Background

  12. Sky maps: 1ES 0647 Reflected Region Background Ring Background

  13. Point source upper limits • Using Helene method • Using Reflected Region results • Crab % calculated using Crab rate at the mean elevation of the observations.

  14. Swift Observations of LSI+61303 BAT 15 - 150 keV XRT 0.3 - 10 keV UVOT 170-650nm

  15. September October November December Observations • 24 observations so far (as of December 19th) • Total exposure ~50ksecs • Observations ongoing

  16. XRT Results • Strong detection with each exposure

  17. XRT Results • Clear variability in light curve (factor of 5)

  18. UVOT • Images taken with a range of filters • Mostly at shorter wavelengths

  19. UVOT • Example image with a blue filter • LSI is one of the brightest objects in the frame

  20. Summary • This was the multiwavelength state-of-the-art view before this year. • Mainly non-contemporaneous • Swift/VERITAS observations will greatly improve this • We should keep observing LSI!

  21. Magnetic Massive Stars as TeV source candidates Jamie Holder University of Delaware VERITAS Collaboration Meeting, Tucson, January 2007

  22. Introduction • Wolf-Rayet stars generate strong stellar winds • Integrated over their lifetime, the wind energy output is ~1037ergs/s • In Wolf-Rayet binary systems (e.g. WR20a) winds from two 70Msol stars collide with a relative speed of ~1000 km/s • This forms a shock region, where particle acceleration can occur (e.g. Bednarek 2005, Pittard 2006)

  23. HESS Result • HESS have recently detected emission from the region of WR20a (9σ result) • Extended ~0.2° • Flux ~10-15% Crab • Steady emission • Spectrum ~Crab-like • Offset w.r.t. WR20a

  24. HESS Interpretaion • WR 20a itself would be a point source • Westerland 2, a stellar cluster with massive star formation (Chandra sees 500 X-ray sources here). • Radio observations reveal wind blown "bubbles" around WR20a and WR20b and the core of Westerland 2, and a "blister" to the west, where the "bubble" is expands into a less dense region of the ISM. Radio Map (843MHz) WR20a WR20b

  25. Northern hemisphere: WR140 • Another colliding wind binary (Wolf-Rayet and O-type star) • RA= 20h 20m, dec=+43 degrees • Summer source (bad!), but unique to northern hemisphere (good!) • Pittard & Dougherty: • Integral predicted flux >1TeV= 1.2 × 10-14 photons s-1 cm-2 • requires >50 hours, but in the light of HESS result, who knows?

  26. Northern hemisphere: σ Ori E • Most massive stars do not have strong magnetic fields; however, there exist a class of magnetic massive stars • Bp stars: chemically peculiar (helium rich) • Magnetic fields of ~ 10,000 Gauss • These fields can channel the hypersonic, radiation-driven stellar wind into violent collision with itself, generating a shock of similar magnitude to a colliding wind binary system (Townsend and Owocki, 2006).

  27. Northern hemisphere: σ Ori E • RA 05h 38m dec -02° 32' • Visible now, to northern and southern hemispheres • In the same field of view are star clusters; e.g. NGC 2024 • Chandra sees 283 sources in this star-forming region • May have some trouble with bright stars... • 10 hours in January would give us a strong upper limit on this new candidate source class. NGC 2024 The flame nebula

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