Prashanth Jaikumar
California State University Long Beach
March 28-29, 2011
! Collaborators: Brian Niebergal (Scotia Bank), Rachid Ouyed (U.Calgary)
3rd Mini-Workshop on Neutron Stars and Neutrinos, Arizona State University (Organizers: Cecilia Lunardini and Igor Shovkovy)
Introduction
Part 1: Strange Quark Matter (SQM) • Hypothesis • Strangelets • Neutron Stars vs. Quark Stars
Part 2: Numerical Studies of Combustion • Previous work • Setting up Reactive Diffusive Hydrodynamics • Simulation Results (1D) • Astrophysical implications
Images from http://www.paultan.org
Witten (1984) argued that at high density, bulk SQM can be more stable than nuclear matter
µ(uds) ≈ 0.89µ(ud)
Witten Hypothesis: Quark matter with (u,d,s) may have lower energy/baryon
1. Coulomb energy disfavors very large blobs 2. Surface tension disfavors very small blobs 3. Interactions (α_strong) favor more strange quarks
The estimates are model dependent and fairly simplistic
Berger & Jaffe: PRC 35, 213 (1987)
1. Primordial (Witten): 1st order PT in Early Universe (T ~ 200 MeV) Strangelets formed by freezing of lumps with baryon excess inside
2. Heavy-ion Collisions: Forward rapidity region at RHIC Short lifetime; production rate < 1 in 10^6 collisions for 0.1ns or more (STAR)
3. Binary collision of strange stars (if they exist) can eject strangelets Expected strangelet flux is below current detection limits (1 in 10^14 for A~1000)
April 19, 2011: AMS-02 launched for use at ISS; should find CFL strangelets
Q: Can these 2 classes of stars co-exist?
Answer: Its possible!
Reason 1: Strangelets have some + charge, so repel ordinary nuclei. Quark Star with nuclear crust may exist.
Reason 2: Limits on Strangelet flux from binary SS collisions less than NS-NS collisions (Bauswein, PRL 103, 011101 (2009))
u,d,s- quark core - lambda clustering - neutrino sparking - outside strangelet
Olinto (PLB 192, 71 (1987)): 1D Reactive-Diffusive Diffusion of massless strange quarks across a zero-width interface
a(x) = (nd − ns)/(nd + ns)
a(x) = −D∇a+R(a)
R(a) is a reaction rate d+u -> u+s
Steady State Result: v = x ∼�
D
τ≈ 10− 100 km/s
( Horvath & Benvenuto (1988), Cho (1984), Lugones (2002), Drago et al., ApJ 659, 1519 (2007) )
Drago et al. found that for a variety of QM and NM EOS,
1) Only Deflagration, no Detonation 2) Instabilities in Laminar Flow
h = 4(P+B) Finite-T Bag model
Interface slowed and halted by advection (jump conditions)
Neutrino emissivity peaks in the interface region
Brian Niebergal's webpage
1) Vburn = 0.002 to 0.04c - Faster than analytic estimates
2) Neutrino cooling is essential - determines progress and fate of interface
3) Transition may be explosive? (Quark-Nova)
- Publicly available !(http://quarknova.ucalgary.ca/)! - Burn Hadrons -> SQM! - Study conversion speeds!
Parent Neutron Star
A B
C
A) Initial laminar burning -> fast
B) Instabilities -> Rayleigh-Taylor, Landau-Darrieus etc. -> Detonation?
C) Deleptonization -> Interface halts! -> 2nd Core collapse.. ->Black-Hole?
If detonation can be achieved, binding energy release is huge and fast ~ 10^52 ergs
Quark matter in Neutron Stars: Quark-Novae: Gamma-Ray Bursts Neutrino Burst Gravitational Waves: Nucleosynthesis:
Multi-D simulations:
Wrinkling instability of Interface versus diffusive stabilization
Equation of State :
Mixed Phases, Color Superconductor..
1. Detecting Quark Matter in Neutron Stars is Elusive – Deflagration Detonation Quark-Nova
2. 1D simulations indicate fast burning speeds, but neutrinos slow it down
3. Multi-D simulations are planned for the future – unstable front..?
4. Many astrophysical applications where burst of energy arises in short time - Most likely from compact star phenomena...
Numerical simulation of the hydrodynamical combustion to strange quark matter
Brian Niebergal, Rachid Ouyed, and Prashanth Jaikumar
PHYSICAL REVIEW C 82, 062801(R) (2010)