Title Page

Outline

1. Introduction

2. Physical Modeling

3. Numerical Results

4. Summary

FIZZLERS: WHAT AND WHO ARE THEY?


    What is a Fizzler?

      Stable, stationary degnerate equilibria do not exist between white dwarf and neutron star densities because of the large effective adiabatic index for dense material. However, for degenerate objects which rotate sufficiently rapidly, equilibria exist at the intermediate densities. Whether the equilibria are stable or not is to be determined. Objects may form in the intermediate density regime in the aborted supernova outbursts of rotating stars. Such objects were coined Fizzlers by Tommy Gold in the 1970s. Interest in fizzlers has recently picked up because they may be strong sources of gravitational radiation.

    What is the J-Threshold?

      A collapse will fizzle if the centrifugal acceleration becmes comparable to the gravitational acceleration near the equator of the star. That is, if

        (v2/R)/(GM/R2) ~ 1

      we expect rotation to be important. For a collapse problem, if we relate the velocity v to the conserved angular momentum J, we have

        (Jt/I)2(R3/GM) ~ 1

      where Jt is the critical angular momentum momentum and I is the moment-of-inertia of the star. To within constants of order unity,

        Jt2 ~ GRM3 ===> J > Jt = 2x1049 g cm2 s-1,

      halts collapse before neutron star parameters are reached. To halt collapse at lower density (larger R), requires larger J.


    Are There Reasonable Fizzler Candidates?



      Ref.: Kawaler, S. 1987, P.A.S.P.,99,1322


      The rough J(M)-relation is

      J ~ 6.3x1049 (M/Mo)2 g cm2 s-1.

      Extrapolating suggests that a 20 Mo star contains roughly 2.5x1052 g cm2 s-1. However, it is the core J which is relevant (and unobservable).

      Recent calculations of evolving rotating massive stars by Heger, Langer, & Woosley (2000), suggest that such stars are likely to produce Fe cores with specific angular momenta ~1016 cm2 s-1, fairly independently of the initial J and M of the main sequence star. So, for 1.4 Mo Fe cores, J ~ 3x1049 g cm2 s-1, near the approximate fizzler threshold of above.