VHE emission from binary systems Outline Binary systems
VHE emission from binary systems Outline • Binary systems • Microquasar • Pulsar binaries • The MAGIC telescope • Observations of LS I +61 303 • Conclusions Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Binary systems System of two stellar objects or one stellar and one compact object More interesting star + compact object Compact objects: Black Hole Neutron Star HMXB High Mass X-ray Binaries LMXB Low Mass X-ray Binaries Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Microquasar Special Binaries: • Accretion powered • Relativistic plasma outflow (jet) emitting at radio frequencies • Downscaled versions of the extragalactic quasars • Companion star O or B star • relativistic jets with v ~ 0. 6 c Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Microquasars Very interesting objects: Timescales of processes scale with the mass of the black hole! Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Accretion the central engine Two mayor types of accretion possible depending on the companion star. Strong stellar wind which is accreted by the compact object moving in the wind Companion star overfills its roche lobe and mater flows onto compact object Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
The different states Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Energy spectrum of Cygnus X 1 Different components: low hard state • unscattered black body • Fe Kα / compton reflection • main comptonization component (scattered by e) • different compton scattering not in the hot disc high soft state Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Jet as the source of VHE -rays Details of Jet formation unknown! Magneto hydrodynamic simulations (MHD) show relativistic plasma outflows. Radio jets Tobias Jogler X-ray jets Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Particle acceleration in jets SSC (Self Synchrotron inverse Compton) model • Te. V energetic electrons in the jet emit synchrotron radiation • Te. V electrons up scatter (IC) the synchrotron γ to VHE Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Binary pulsars Rotational powered Pulsar creates relativistic Pulsar Wind Nebula (PWN) PWN are emitter of VHE γ - rays (maybe the dominant) Variability of source due to absorption Very interesting to understand colliding winds and shock formation Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
The MAGIC telescope La Palma, asl. 2200 m 17 m diameter Mirror 3. 5 ° Fo. V Camera Trigger Threshold of E = 60 Ge. V Sensitivity of 2. 2 % Crab flux Can operate under moonlight conditions Very sensitive Instrument to study faint VHE gamma ray sources Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Imaging Air Cherenkov Telescopes Gamma ray Particle shower Cherenkov light Image of particle shower in telescope camera ~ 1 o Che ren k ov l igh t ~ 10 km ~ 120 m Tobias Jogler Reconstruct: arrival direction, energy reject hadron background Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Observations of LS I +61 303 Observed during two cycles with the MAGIC telescope 2005 -2006 Variable source which emits mostly around phase 0. 6 Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Spectral behavior Spectra for different orbital phases Spectral behavior is stable even if flux changes by factor of 3 Sensitivity to shape of the spectrum is limited by statistics LS I +61 303 is more luminous in VHE than in the x-ray band! Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Short time variability Search for short time variability on timescales 30 -120 min Two long nights with t > 5 h No short time variabillity found within the sensitivity of MAGIC Tobias Jogler Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
Conclusions • • • Tobias Jogler Different Binary types can produce VHE γ-rays Very interesting field with unique possibilities Many open questions Detailed studies need a lot of observation time With detailed, simultaneous studies at different wavelength models can be constrained Max-Planck Institut für Physik IMPRS YSW Ringberg 2007
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