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Short Story

Short Story. BAT detects the spectral signature of cold, otherwise invisible particles, in two powerful quasar jets For the first time we can count ALL particles in the jet! Energy budget of jet dictates heavier particles MUST be present: PROTONS. Powerful quasar jets are made of e-p.

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Short Story

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  1. Short Story • BAT detects the spectral signature of cold, otherwise invisible particles, in two powerful quasar jets • For the first time we can count ALL particles in the jet! • Energy budget of jet dictates heavier particles MUST be present: PROTONS Powerful quasar jets are made of e-p

  2. Cosmic fireworks Jets originate near the supermassive black hole

  3. They move FAST • … almost as fast as light: v=0.999c! • Relativistic • This enhances the emitted light (beaming); very bright, visible from very far

  4. What are jets made of?A long standing debate • Matter; magnetic fields • Must be neutral: either pairs e+e-(electron-positron) or electrons-protons e-p • Which one: pairs or e-p?

  5. The long story… How we weigh jets (1) • We see the hot (relativistic) particles because they emit light • Comptonization allows us to see the cold (non relativistic) particles

  6. How we weigh jets (2) • Cold particles Compton-scatter external radiation around jet • A big bump in the X-ray light distribution, peaking at 10 keV • Never observed before! Too small energy window, intrinsically transient feature • When bump observed: derive number of cold (invisible) particles

  7. Extract a spectrum (distribution of light with energy) BAT observes 4 quasar jets • Distance ~ 11 billion light years • Luminous! • Shining in our eyes A BAT Image

  8. Light distribution As observed before. Boring!!

  9. The other two: Surprise The big bump! Signature of COLD particles

  10. Need protons! • Energetic budget of jet: to keep up motion need to have Pjet >> Lrad kinetic energy must be larger than emitted energy • Pairs do not make it – too light

  11. Why protons? • Make jet neutral • Heavier than electrons, can carry the momentum/kinetic energy further down the jet Total mass in the jet: about 1 planet Jupiter

  12. Summary • Jet composition is no longer a mystery • Energy budget of jet dictates heavier particles MUST be present: PROTONS • Total mass in jet: 1 Jupiter • Swift paves the way for GLAST

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