Collapse to Black Holes in Brans-Dicke Theory: I. Horizon Boundary Conditions for Dynamical Spacetimes

TL;DR

This paper introduces a new numerical code for simulating gravitational collapse in Brans-Dicke theory, capable of tracking black hole formation in dynamical, radiative spacetimes without singularities.

Contribution

The authors develop a novel numerical method that evolves spherically symmetric collapse in Brans-Dicke theory, handling horizons and radiation effectively.

Findings

Successfully simulates collapse to black holes in Brans-Dicke theory.

Handles dynamical spacetimes with gravitational radiation.

Addresses longstanding theoretical questions about black hole formation.

Abstract

We present a new numerical code that evolves a spherically symmetric configuration of collisionless matter in the Brans-Dicke theory of gravitation. In this theory the spacetime is dynamical even in spherical symmetry, where it can contain gravitational radiation. Our code is capable of accurately tracking collapse to a black hole in a dynamical spacetime arbitrarily far into the future, without encountering either coordinate pathologies or spacetime singularities. This is accomplished by truncating the spacetime at a spherical surface inside the apparent horizon, and subsequently solving the evolution and constraint equations only in the exterior region. We use our code to address a number of long-standing theoretical questions about collapse to black holes in Brans-Dicke theory.