Tuesday April 4: Direct Observational Constraints on Black Hole Driven Jets

Event Date: 

Tuesday, April 4, 2017 - 4:00pm

Event Location: 

  • Broida 1640
  • Physics Colloquium


Astrophysical black holes with jets of synchrotron emitting plasma can be supermassive (millions to billions of solar masses) or a few solar masses in stellar binary systems. The black hole accretion system can launch jets driven by the rotation of large scale magnetic field lines that is induced either by the in-spiralling matter or the rotation of space=time itself (frame dragging). In the past five years, direct observations of the emission from the jet launching region near black holes has been published. The data does not support a "one idea fits all", scale invariant, standard model of jet launching. Jets from tellar mass, Galactic black holes (GBHs), are different than supermassive black hole jets in Radio Loud Quasars (RLQs). This raises the new physical question, why? A black hole has no intrinsic electromagnetic field that is magnetic. Magnetic "hair" must be imposed by the accreting plasma. The differences between jet launching in GBHs and RLQs seems to reflect differences in the accreting plasma physics.

In RLQs, a deficit of emission form the innermost accretion flow is associated with jet (with a bulk Lorentz factor ~10) launching and the magnitude of the deficit of this emissiom scales with jet power.

GBHs have two modes of jet production. In direct contrast to RLDs, discrete "superluminal" ejections (bulk Lorentz factor ~1.2 -1.9) have a "jet" power that scales with the magnitude of a strong powerlaw X-ray flare (that can approach the Eddington luminosity for strong flares) that initiates prior to the ejection by minutes to hours. The other mode, the continuous compact jet (bulk Lorentz factor ~ 1.0 -1.1) has a radio luminosity that scales with the luminosity of the hard X-ray powerlaw which can exceed 50% of the Eddington luminosity for the strongest compact jets.