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Jamie Holder VERITAS Collaboration Bartol Research Institute/ University of Delaware

LS I +61 ° 303: The High Energy View. Jamie Holder VERITAS Collaboration Bartol Research Institute/ University of Delaware. "Getting Involved with GLAST" Workshop, Harvard, June 2007. LS I +61° 303.

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Jamie Holder VERITAS Collaboration Bartol Research Institute/ University of Delaware

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  1. LS I +61° 303: The High Energy View Jamie Holder VERITAS Collaboration Bartol Research Institute/ University of Delaware "Getting Involved with GLAST" Workshop, Harvard, June 2007

  2. LS I +61° 303 • HMXB composed of a Be star with circumstellar disk and a compact object (neutron star or BH) • highly eccentric ( e=0.72±0.15) • distance 2 kpc • orbital period 26.4960 days (strong periodic radio outbursts) • Detected by COS-B; confirmed by EGRET • MAGIC detected variable TeV emission J.Casares et al (MNRAS 360, 1105 (2005))

  3. LS I +61° 303: High energy emission.

  4. Romero et al. astro-ph/0706.1320 Dhawan et al. Proceedings of the VI Microquasar Workshop LS I +61° 303: supporting evidence pulsar wind Be star wind • Radio observations show rotating tail • X-ray observations show no spectral features (no jet break, accretion disk bump) • Supports pulsar wind model • Relative wind strengths are such that you cannot produce simple elongated shape seen in VLBI images. • Gamma-ray lightcurve is more easily explained by variable accretion • Prefer microquasar model • Within both of these scenarios, the details can still vary widely: e.g. leptonic or hadronic particle acceleration? Importance of Be star wind clumping? Is the gamma-ray lightcurve dominated by photon-photon absorption? etc etc.

  5. LS I +61° 303 - data Chernyakova et al. MNRAS, 372, 1585, 2006 • Also 50ks exposure with Chandra at phase 0.0 • but, in general, we don't have a very detailed picture of the emission from LS I +61° 303

  6. LS I +61° 303: VERITAS-II Results Maier et al, Merida ICRC , 2007 • 44 hours of data from September 2007 - February 2008 • Majority of observations with only two telescopes • Four Telescopes now operating - sensitivity for future observations will be much better. measured3 Telescope sensitivity

  7. LS I +61° 303: Swift Results Holder, Falcone & Morris, Merida ICRC , 2007 • Swift XRT observations from September to December 2007 • Preliminary analysis shows strong variability • Orbital structure of lightcurve is not terribly clear • Contemporaneous UVOT data also available

  8. LS I +61° 303: Summary and Straw Proposal • In order to constrain the models and understand the nature of LS I +61 303 and the origin of the high energy emission we need better data • This must be contemporaneous, broad-band, well sampled, and with time resolved spectra. • It should cover multiple orbital cycles • GLAST will provide excellent coverage over its energy range • These observations should be supported at other wavelengths by e.g.: • TeV: VERITAS-IV / MAGIC (II?) • Optical: Swift / VERITAS Multiwavelength Associates • X-ray: Swift / RXTE • Radio: NRAO? • A possible scenario, at least for VERITAS-IV, would be to make limited observations in the 2007 - 2008 observing season, then sample every few days from September 2008 - February 2009, as well as taking a deep exposure over one orbital cycle. • Other ideas/ suggestions welcome!

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