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The Character of High Energy Emission From The Galactic Binary LS 1 +61 303

The Character of High Energy Emission From The Galactic Binary LS 1 +61 303. Andy Smith Smithsonian Astrophysical Observatory (for the VERITAS collaboration). LS 1 +61 303. -High Mass X-ray Binary -BH or NS? -26.496 day period -periodic outbursts in X-ray, radio, GeV ,

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The Character of High Energy Emission From The Galactic Binary LS 1 +61 303

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  1. The Character of High Energy Emission From The Galactic Binary LS 1 +61 303 Andy Smith Smithsonian Astrophysical Observatory (for the VERITAS collaboration)

  2. LS 1 +61 303 -High Mass X-ray Binary -BH or NS? -26.496 day period -periodic outbursts in X-ray, radio, GeV, and TeV gamma rays!

  3. LS 1 +61 303 Archival X-ray Outbursts (ROSAT,RXTE, XMM-Newton)

  4. LS 1 +61 303 TeV Emission (MAGIC)

  5. LS 1 +61 303 LS 1 +61 303 TeV Emission (MAGIC, VERITAS Radio Emission (VLA, GBI)

  6. Microquasar or Binary Pulsar?

  7. LS 1 +61 303 However, identification of system still an open issue- multiwavelength observations (with TeV) help to constrain rise time of high energy emission in different bands Pulsar Model given support by VLBA monitoring No X-ray or radio pulsations detected, but… Dhawan et al 2006

  8. VERITAS LS I +61 303 Observations: - New TeV Array in S. Arizona (see T.Weekes on Sat) -Sensitive in range 100 GeV->20 TeV -44h of data from September 2006-February 2007 -Observations covered phase bins 0.2-0.9 ->10 sigma detection in “active” phase bins (0.5-0.8)

  9. Phases 0.5->0.8

  10. TeV activity coincides with near-apastron passage

  11. Multiwavelength Monitoring • ToO observations approved for SWIFT and RXTE in late 2006 • RXTE: 2-10 keV monitoring in October • SWIFT 0.2-10 keV monitoring Sep->Dec (PSU data reduction: A.Falcone,D.Morris) • Flares observed by both instruments around phases 0.6->0.7

  12. Contemporaneous observations during Tev/X-ray flaring states

  13. Very high flux seen in both bands on same night- spectral analysis forthcoming

  14. Contemporaneous observations during X-ray flaring states

  15. TeV emission elevated, but not maximal Local TeV Peak Local X-ray Peak X-ray emission elevated, but not maximal

  16. Active TeV regions Active X-ray Regions

  17. Summary so far… • VERITAS observations confirm detection of LS 1 +61 303 as variable TeV source • One of 3 known “TeV” binaries- new class of sources • Multiwavelength observations show elevated TeV emission correlated with elevated X-ray behavior (not necessarily bijective....) • SWIFT observations show secondary X-ray peak near pre-periastron passage- no TeV observations yet for this region.

  18. Latest Observations…… TeV Emission X-ray Peaks

  19. Microquasar Scenario: X-ray Accretion Disk- ->Radio Loud Jets ->Upscatter stellar photons to TeV energies TeV Emission Accretion driven emission during and after density peaks. Supporting Evidence: -MERLIN Imaging -TeV emission agreeable with “Second Peak” Cons: No spectral evidence for accretion Where is primary peak?

  20. Or…….. Binary Pulsar Scenario: Shock acceleration at interface between pulsar and stellar wind drives X-ray/TeV emission- radio emission from cometary tail Cons: -No evidence for pulsations -Is stellar wind stronger than pulsar wind? -Difficult to say without greater understanding of orbital geometry Observational Evidence: -VLA imaging strongest evidence -Close rise time of X-ray/TeV emission

  21. Secondary X-ray Peak? TeV Emission X-ray Peaks

  22. Summary • Latest high energy observations of LS 1 +61 303 show evidence for correlation between X-ray and TeVbehavior • No clear indication of fundamental identification of system • Regardless of nature (MQ vs BP) , it is evident that “local“ compact systems are able to accelerate (most likely) electrons to TeV energies . • TeV binaries represents ideal laboratories for observations of high energy emission in the presence of strong gravity stellar environments.

  23. Watch this space....... • RXTE monitoring approved for bi-nightly observations from September 2007-->February 2008 • This, combined with TeV monitoring from VERITAS, will allow first multiwavelength observations taken between phases 0.9->0.2: more accurate measurement of full cycle behavior • If LS1 is a black hole, will add to study of BH dynamics. If it is a binary pulsar, will add to study of pulsar wind acceleration

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