Assistant Professor at the University of Birmingham

Disc formation simulations

The main results described in this paper are shown in the five movies below. In the first three, the orbit of the disrupted star is fixed (with an eccentricity e=0.8 and a penetration factor β=5) varying both the gravitational potential (either relativistic or Keplerian) and the cooling (either efficient or inefficient). In the last two, the gravitational potential and the cooling are fixed (to relativistic and efficient) and the orbit of the star (either the eccentricity or the penetration factor) is varied.

1. Relativistic potential and efficient cooling (model RI5e.8 in the paper): relativistic apsidal precession induces self-crossings of the stream which generate shocks. As a result, the debris move from their initial eccentric orbits to circular orbits. They settle into a thin and narrow ring.

2. Keplerian potential and efficient cooling (model KI5e.8 in the paper): when relativistic precession is switched off, the debris keep their initial eccentric orbits instead of moving to circular orbits. They settle into an elliptical structure.

3. Relativistic potential and inefficient cooling (model RA5e.8 in the paper): the debris settle into a thick and extended torus instead of a thin and narrow ring.

4. Lower penetration factor of β=1 (model RI1e.8 in the paper): as the stream passes further from the black hole, apsidal relativistic precession is weaker which leads to weaker shocks. As a result, the debris move slower to circular orbits.

5. Larger eccentricity of e=0.95 (model RI5e.95 in the paper): as the stream is more eccentric, it self-crosses after its first passage near the black hole which involves more material. Therefore, the debris move faster to circular orbits.