Burst3D · Type I bursts in 3D
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2016-10-01 → 2019-09-30
- EU contribution
- €251,858
- Participants
- 2
- Scheme
- MSCA-IF-GF
Lines connect the coordinator with its partners.
Results in brief
Type I bursts in 3D
Dr Cavecchi runs computer simulations of the Type I Bursts that take place on neutron stars. The neutron stars are fascinating objects that result from the explosion of massive stars, the so called supernovae. What is left of the core of the original star collapses to form a new object, the neutron star, which encloses the mass of almost two suns within 10 Km; the approximate size of a small city. Due to their high mass in such a small volume, the density of matter near the centre of the neutron stars exceed even the density found in the nuclei of atoms on Earth. The physics governing this state of matter is not well understood and is the subject of theoretical and experimental work. The neutron stars offer a great opportunity to study the behaviour of this matter, but the centres of the stars cannot be observed directly and we have to reply on other proxies. The Type I Bursts are thermonuclear explosion on the surface of neutron stars that strip matter from a companion star. They produce extremely bright X-ray flashes that makes them ideal to observe the neutron stars. Dr Cavecchi runs magnetohydrodynamical simulations of these explosions, trying to understand how the nuclear flame propagates on the surface of the star. With precise models of the flame propagation, it is possible to construct synthetic images of the bursts that, once compared to the observed ones, can inform us about the properties of the star where they burn. In this way, we can shed light on the mysterious behaviour of matter in the centre of the neutron stars. During this action, Dr. Cavecchi showed how to reconcile the theory of nuclear burning with the observed frequency of ignition of Type I Bursts. He also showed how the subsequent flame propagates. Contrary to our previous picture, the flame does not develop with an orderly front: the latter breaks down into small vortices which make the flame proceed up to 10 times faster. These vortices may also hold the key to explain the lightcurves during the cooling phase of the bursts.
Data: CORDIS, © European Union
Project objective
On Earth, nuclear explosions take place in controlled environments or use small amounts of fuel. Despite that, they generate spectacular amounts of energy. When nuclear reactions ignite on a neutron star, the whole surface can burn, resulting in extremely bright X-ray flashes that outshine all the other emission. These flashes are known as type I bursts. Their emission encodes information about the neutron star mass and radius and this makes them ideal probes to explore such stars' properties.Much effort has been invested to describe nuclear explosions, both on Earth and in space, but the modelling of the type I bursts entails extra difficulties. In particular, simulating deflagrating flames in the extreme conditions of neutron stars has proven particularly challenging. Nonetheless, in the last several years I have been able to produce the first ab initio 2D simulations of type I bursts where the deflagration takes place inside a burning hurricane that expands to engulf the whole surface of the star. However, 2D simulations have inherent limitations.With this project I intend to model the nuclear explosions during the bursts combining detailed microphysics with a magnetohydrodynamical description set for the first time in a 3D spherical geometry to be able to capture the combination of all the relevant effects. Understanding all the different facets of the bursts and their physical ingredients, I will produce unprecedented simulations which I will couple to a ray tracing code that takes into account the general relativistic effects of the star's gravity and rotation on the emitted photons. I will be able to produce extremely accurate synthetic lightcurves to confront with the observations in order to extract the information about the neutron star contained in the X-ray emission. Once the parameters of the bursters are known, these can be used to constrain the yet unknown behavior of matter in the core of neutron stars.
Original text from CORDIS.
Participants
- UNIVERSITY OF SOUTHAMPTON · SOUTHAMPTONCoordinatorUnited Kingdom
- TRUSTEES OF PRINCETON UNIVERSITY · Princeton, NjUnited States
Links
Data: CORDIS, © European Union