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Survey of Micro Quasars

Survey of Micro Quasars. Outline. Reminder: what is a microquasar? Established and Candidate microquasars Gamma ray candidates: LSI +615, LS 5039 As seen in DC2 Models for gamma ray spectra. What and Where. High Mass XRB live near galactic plane Low Mass XRB live in the bulge.

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Survey of Micro Quasars

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  1. Survey of Micro Quasars

  2. Outline • Reminder: what is a microquasar? • Established and Candidate microquasars • Gamma ray candidates: • LSI +615, LS 5039 • As seen in DC2 • Models for gamma ray spectra

  3. What and Where High Mass XRB live near galactic plane Low Mass XRB live in the bulge microQuasar ≡ X-ray binary with jets

  4. Candidate Microquasars * * * * * - g-ray candidates

  5. LS 5039 & LS I +613 • 2EG J0431+6119 (aka 3EG J0435+6137) • = 9.2±0.6 x 10-7 cm-2s-1 E>100 MeV • = 2.46 Not visible by HESS •  = 35.2 x 10-8 cm-2s-1 E>100 MeV • = 2.2 HESS: G=2.12

  6. HESS: Detected again this year H.E.S.S. preliminary LS 5039

  7. H.E.S.S. lightcurve (2004) LS 5039 Aharonian et al., Science 309(746 ), 2005 No significant variations

  8. H.E.S.S. spectrum: hard O6V star LS 5039 Aharonian et al., Science 309(746 ), 2005

  9. LS 5039, LS I +615 & Friends Candidates in DC2 Toby’s HEALPIX map + Saclay sources SS 433 GRS 1915+105 Circinus X1 XTE J1550-564 GGRO J1655-40 V 4641 Sgr GRS 1758-258 Cyg X1 GX 339-4 1E 1740.7-294.2 Cyg X3 LS5039 G = -2.42 LS I +615 G = -2.75

  10. Models for g-ray Emission log eL e(erg s -1)

  11. Standard Disk Model: Star, Disk, Corona • Star • blackbody – T ~ 104K – peak @ kT – E ~ 10 eV • Accretion Disk • Energy emission due to angular momentum transport • Inner radius ~3rs≈ 9 Mx km (eg 18 km for 2 solar masses) • Tin ~ 2 107 K • 1 solar mass  10M K  ~ 1 keV • Integrate radial temp spectrum

  12. Standard Disk Model: Hard X-rays • Observations show hard x-ray spectra • Requires 109 K • Hence postulate corona

  13. Dynamics in Disk-Jet System High luminosity from inner disk; Soft x-rays GRS 1915+105 Low luminosity from corona; Hard x-rays T (hrs)

  14. Jet Observations • mQ jets too small to image anytime soon • complicated MHD calculations! • practical models of jets used in calcs: • inject blobs of plasma at some height above the disk, bulk Lorentz G (eg 5) • isotropic lepton spectrum in blob, power law (-2) with min, max g corresponding to inferred max E in TeV range

  15. Jet Interactions with Stellar Photon Field

  16. Jet Interactions with Disk, Corona

  17. Leptonic Jet Models Dermer G=2; p=2.25 Includes gg annihilation with stellar field Parades G=1.1; p=2.2 • Inverse compton from star dominates at high energy • ignores variability and non-contemporaneous measurements

  18. Recall from mQ II: LS 5039 Spectral fitassuming it is a pulsar G.Dubus Pulsar wind parameters: 1036 erg/s, gw=106 and s=0.001 no absorption nebular emission But TeV and star photons create e+e- pairs ! Dubus, in prep.

  19. Additional Variability • Two potential sources: • Precession of jet by drag of star gravity on disk • Assumed to transmit to jet For “LS5039”; q~100  T~ 100 days Huge variation depending on angle of jet to disk GRO J1655-40, V 4641 Sgr show significant misalignments SS 433 shows 162 day period

  20. Variability 2 • Orbital effects on accretion (“two-peak” accretion model) and extinction of g’s by stellar field Lower density wind Lower compact obj speed High density wind High compact speed Colours represent 3 epochs Dubus From mQ II: Extinction at high E due to gg interactions vs orbital phase

  21. What will GLAST Contribute? • There is only statistics of TWO for observations in GLAST energy range (LS 5039, LS I +613) • And LS 5039 might not even be a microquasar! • Need more candidates • Survey mode should allow us to examine known candidates • Hopefully ACTs will see more (eg LS I +613 from some northern telescope?) before we go up • Definitive IDs from precise positions, variability • Keep an eye out for variability • MW observations with x-ray, radio • Correlate gamma ray variability with disk-jet variations? • Untangle precession, orbital effects • Hopefully more understanding of disk-jet variations by then

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