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)