Who needs charge neutrality?

17.42 Final talk of the day "Effects of Ultra-Strong Electric Fields in Compact Stars" Manuel Malheiros, the man who guided us safely back from downtown Joao Pessoa at 2am last night.

17.52 Looks like he's going to take on some inviolable tenets of neutron star structure - namely the assumption of local charge neutrality. We're going to relax this to global charge neutrality. This should be good.

17.57 We're promised new effects from electric fields in gravity. Enticing....

17.58 Neutron star vital statistics are shown. Electric fields of 10^14 - 10^18 V/cm are the surprise one. Ok, how's this going to work?

17.59 The basics of neutron star physics are (very) rapidly covered: composition, structure, TOV equations (general relativistic hydrostatic equilibrium), the unconstrained nature of the core physics. Half of Shapiro and Teukolsky seems to flash by my eyes in 60 seconds.

18.06 We get to the new stuff. Basically - If neutron stars are gravitationally bound, neutrons are unbound, and COulomb is only a small addition, why can we not have a small amount of charge asymmetry? Back of the envelope calculations show that one can have a charge equal to the square root of the gravitational constant times the mass of the star. This is similar to the charged black hole relation. Intriguing...

18.13 With an E-field, TOV equations are modified - the E-field couples to gravity in general relativity.

18.14 And time is up, so results are going to come thick and fast now...

18.15 Max mass changes with an E-field. More charge, greater max mass, and greater radius - which is intuitive, since the E-force is repulsive. This is the main effect of relaxing local charge neutrality.

18.16 Two minutes after the end of the talk, and we are on to the second section of the talk. I'm not sure I'll be able to keep up.

18.18 The second section is strange stars, specifically the appearance of an electrostatic layer at the stars surface caused by a separation of the quark matter and electrons.

18.25 A question that I was wondering myself is asked - where would the charge, or charge separation, come from? What is the mechanism that produces local charge non-neutrality? Answer - there isn't one! His point is to raise the possibility, rather than postulate the physical mechanism.

18.28 And that's it! Until next time....