theory of pulsar winds
DESCRIPTION
F. Curtis Michel Rice University 13 July 2005. Theory of Pulsar Winds. http://psr.rice.edu/PulsarMech. Valued Coworkers. Bonnie Hausman Hui Li Ian Smith Steve Sturner Jurgen Krause-Polstorff. Encyclopedia of the Future. Article: “How Radio Pulsars work” (outline). - PowerPoint PPT PresentationTRANSCRIPT
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Theory of Pulsar Winds
F. Curtis MichelRice University
13 July 2005
http://psr.rice.edu/PulsarMech
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Valued Coworkers
Bonnie Hausman
Hui Li
Ian Smith
Steve Sturner
Jurgen Krause-Polstorff
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Encyclopedia of the Future
Article: “How Radio Pulsars work” (outline).
Rotating NS + B -> central Q + quadrupole E field
Neutron star completely surrounded with MHD plasma
Aligned model good as any (“inclination ads nothing new”)
Weak particle acceleration because E fields shorted out
No plausible source of coherent radio emission
No idea of why radio spectrum what it is
Needs another hundred years of careful theoretical work
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Encyclopedia of the Future (alt)
Article: “How Radio Pulsars work” (outline).
Rotating NS + B -> central Q + quadrupole E field
Neutron star surrounded by dome/torus of MHD plasma
Inclined model essential
Huge particle acceleration because E fields not shorted out except in dome/torus of non neutral plasmas (single sign)
Particles accelerated and emit synchrotron gamma rays which magnetically convert to pairs and form dense bunches
Bunches amplify incoherent radiation to provide coherent radio emission and give typical “dirt effect” intensity (0.00001)
Inclination develops Huge EM waves that clear out system
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Aligned MHD model (GJ)
!!!
Electrons turn into protons????
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Well-Known (and Ignored) Pathologies of the Model
1) Assumes MHD everywhere
2) Assumes particles come from surface! Easily shown that this is inconsistent with (1) just above
3) Assumes flow changes sign across a boundary!!
4) Magnetic field lines near and beyond light cylinder purely cartoons
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Phenomenological Hollow Cone Model
Only the most generic connectionwith this model
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
It's all been done before:Proceedings of the American Physical Society
Phys. Rev.73, 5361948
University of California, Los Angeles, California, January 2-3, 1948
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Journal of Geophysical Research Vol. 70, No. 19 October 1, 1965
Electric Field Generated by a Rotating Magnetized Sphere
Edward W. Hones, Jr., and John E. Bergeson
Department of physics and AstronomyState University of Iowa, Iowa City
“Davis [1947, 1948] showed that plasma surrounding a rotating, conductingmagnetized sphere will rotate with the sphere if the plasma particles areis constrained to move along the magnetic lines of force.”
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Summary to here
Aligned MHD model usually credited with “charge density” but this was worked out 21 years earlier and revived 4 years earlier.
Model clearly assumes particles from surface, but clearly particles from low latitudes (+) trapped close to star on huge B fields (torus)
Particles from high latitudes (-) could escape but don't owing to positive charge on star (domes)
MHD true, but only where there is (non neutral) plasma and completely wrong everywhere else
NB: L. Davis, Jr. and P. Goldreich both physics professors, Caltech, 1967-2003
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Fig. 1 from QuietAligned Rotator
Pair productioncan't change resultsignificantly
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Need for quantitative Results
Had Jurgen Krause-Polstorff working at Rice Univ. with Prof.
Dick Wolf while FCM on sabbatical in France
Program was to directly simulate the aligned MHD model by
releasing charges from surface of rotating magnetized NS
Equilibrium conditions imposed by relaxation (to give MHD)
Particles released until none left (self terminating program)
Result, domes/torus with MHD in the domes and torus ONLY
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
The dome/torus of Krause-Polstorff
Dome (“-”)
Torus(“+”)
DiscontinuityMagnetic field line
Equipotential
Neutron star
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Which is right?
●Myth: MHD (everywhere) has to be true so plasma has to be everywhere
●Completely inconsistent with plasma-pulled-from-surface (has to be nonneutral!).
●Modified program to act “dynamically” to show that even if one forcedthe solution to be that of the aligned MHD, it simply fell apart!
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Collapse of GJ to Dome/Torus
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Backup Stills of GJ collapse to Dome/Torus
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Others who have discovered dome/torus
Shibata, 1989
Rylov, 1989
Zachariades, 1993
Neukirch, 1993
Thielheim and Wolfensteller, 1994
Spitkovski & Arons, 2002
Petri, Heyvaerts, & Bonazzola, 2002
Aly, 2005
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
The “Pulsar Equation”
Rip van Winkle all over again! 1985 to 2005
What has changed? Nothing!
1. Ignore problem (often observational papers)
2. Insist aligned MHD everywhere works (e.g. Mestel et al.)
3. Put in arbitrary “designer” gap to “fix” problem
4. Solve “pulsar equation” (can't work)
but Phys Rev Lett 2005!
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Pelizzari extensions
Assumed simple function
top figure close
computation too difficult (1976)
not important since model unphysical
See Michel, Rev. Mod Phys. 1982, 54, 1
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
The Bunching Mechanism
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Simple Calculation
Charge on neutron star
Curvature of B field
Electric field from Charge
Synchrotron Radiation rate
Synchrotron photon energy
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Remaining Calculations Condition for pair production
Photon energy scaled to electron rest mass
Gamma ray angle to B field
Gammas pair produce:
Bunch size
Coherent photon
Coherent fraction
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Cascade Process
1) Lorentz contracted electron E field
2) Curved “pulse” are the gamma rays
3) Same approx. for Bremmstrahlung
4) Might be underestimated in rates!
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Table listing bunch properties
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Radio Pulsar Efficiencies
Note: radioluminosityonly roughestimate
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Idealized spectrum from spherical bunchesvs
Measured spectrum for B0950
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
What's the point? Standard well-known equations
No “tooth-fairies” required
Coherence due to bunching
Not “simple” but is direct
Efficiency and Spectrum = Radio Pulsars!
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
CriticismsMight be too bright in X-rays (bunches hitting poles)poles covered by domes, acceleration vanishes
New considerations
Jet formation (acceleration of upper parts of domes by the waves)
Positron maintained discharge (from opposite polar caps)
Inclined dipole essential for pulsar action (not just to sweep the
“lighthouse” beam about)
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Crab Movie in X-rays
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Crab Nebula in X-rays
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Things to notice from Movie:
Clear Jet at about 7 O'Clock
Clear equatorial outflow
Inclination of spin axis about 30 deg to LOS
Completely consistent with Dome/Torus
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Truth Table
● Open cascade model● System “empty”● Coherence: bunching● Radio emission
“downwards”● NOT aligned● JETS and equatorial
outflow
● Filled MHD model● System “filled”● No known mechanism● Radio emission
“upwards”● Alignment
“unimportant”● 4pi?
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13 May 2005 F. Curtis Michel Ultra-Relativistic Jets in Astrophysics, Banff, Canada
Encyclopedia of the Future
Article: “How Radio Pulsars work” (outline).
Rotating NS + B -> central Q + quadrupole E field
Neutron star surrounded by dome/torus of MHD plasma
Inclined model essential
Huge particle acceleration because E fields not shorted out except in dome/torus of non neutral plasmas (single sign)
Particles accelerated and emit synchrotron gamma rays which magnetically convert to pairs and form dense bunches
Bunches amplify incoherent radiation to provide coherent radio emission and give typical “dirt effect” intensity (0.00001)
Inclination develops Huge EM waves that clear out system