Report on 2101.08033v1

Abstract

Since the discovery of exoplanets around pulsars, there has been a debate on their origin.Popular scenarios include in situ formation or the dynamical capture of a planet in a dense stellar system.The possibility of a planet surviving its host star's supernova is often neglected, because a planet in orbit around a single exploding star is not expected to survive the supernova.A circum-binary planet, however, may stand a chance in staying bound when one of the binary components explodes.We investigate the latter and constrain the distribution of post-supernova orbital parameters of circum-binary planets.This is done by performing population synthesis calculations of binary stars until the first supernova.Just before the supernova, we add a planet in orbit around the binary to study its survivability.In our supernova model, the exploding star's mass is assumed to change instantaneously, and we apply a velocity kick to the newly formed remnant.The mass loss and velocity kick affect the orbits of the two stars and the planet.Only 2 • 10 -3 of systems survive the supernova while keeping the circum-binary planet bound.The surviving planetary orbits are wide (a > ∼ 10 au) and eccentric (e > ∼ 0.3).It turns out much more likely (3 • 10 -2 system fraction) that the newly formed compact object is ejected from the system, leaving the planet bound to its companion star in a highly eccentric orbit (typically > ∼ 0.9).We expect that the Milky way Galaxy hosts at most 10 x-ray binaries that are still orbited by a planet, and < ∼ 150 planets that survived in orbit around the compact object's companion.These numbers should be convolved with the fraction of massive binaries that is orbited by a planet.

Authors 2

1. Fedde Fagginger Auer Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA , Leiden , The Netherlands

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands

2. Simon Portegies Zwart Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA , Leiden , The Netherlands

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands