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tests:collision:mock_data:challenge_1

Challenge 1: single mass clusters

Isolated models:

The N-body models can be described as:

  1. Initial conditions: Plummer (1911), N = 32768, all stars the same mass
  2. No primordial binaries, no central black hole
  3. Isolation

The data has the following format. Note that the first column can be used to recognise binaries (MN=2). The single components of the binaries are not given.

$M\times N$ $X$ $Y$ $Z$ $V_x$ $V_y$ $V_z$
[NBODY] [NBODY] [NBODY]

Tidally limited models:

The N-body models can be described as:

  1. Initial conditions: Plummer (1911), N = 65536, all stars the same mass
  2. No primordial binaries, no central black hole
  3. Circular orbit in a weak tidal field due to a point-mass galaxy with initially r_jacobi/r_h = 100

The model was ran until complete dissolution (roughly 6e5 N-body times) with Sverre Aarseth's NBODY6. Two-body relaxation drives the evolution: core collapse occurs at roughly T = 1.2e4 and the cluster expands until it fills the Roche-volume roughly half-mass the evolution (T = 3e5). More details about this run can be found Alexander & Gieles (2012).

Below are 3 snapshots at interesting moments of the evolution. The Heggie & Mathieu (1986) N-body units are used: G=M=r_vir=1 (i.e. the mass of individual stars is m=1/65536). The 6 columns contain:

$X$ $Y$ $Z$ $V_x$ $V_y$ $V_z$
[NBODY] [NBODY]
  1. pl_eq_n64k_rjrh100_t012102.gz : In a core minimum just after core collapse [NEW: 19 Aug, 16:15]
  2. pl_eq_n64k_rjrh100_t013650.gz : In a core maximum
  3. pl_eq_n64k_rjrh100_t323790.gz : When ~75% of the stars is lost and the cluster is Roche-filling

Update 14-Oct-2014: More snapshots for this model (roughly) equally spaced by $5\times10^4$ $N$-body times covering the entire life-cycle:

Update: 29 Okt 2014: New version of the 10 snapshots above:

  1. Removed the individual components of binaries, and added the binary com pos and vel in the end of the file
  2. New first column with MxN = 1 for single stars and MxN = 2 for binaries
  3. New column (8) = 1 if r<rt
  4. New column (9) = 1 if E_Jacobi < E_crit

Update 29-Nov-2014:

  1. Fixed bug in energy computation
  2. New column (8): phi (= specific potential)
  3. New column (9); E_J = jacobi energy (see e.g. Fukushige & Heggie (2000), below equation 3)
  4. Added top line with: N, rt, E_crit

First line: N, rt, E_crit

$M\timesN$ $X$ $Y$ $Z$ $V_x$ $V_y$ $V_z$ $\phi$ $E_J$ r < rt E<Ecrit
[NBODY] [NBODY] [NBODY] [NBODY][NBODY]0 or 1 0 or 1

For the last snapshot a table with specific energy and the z-component of the specific angular momentum vector can be found here:

  1. pl_eq_n64k_rjrh100_t323790.ejz.gz : When ~75% of the stars is lost and the cluster is Roche-filling

Note: the initial Jacobi radius of this model was $r_{\rm J}= 78.17$, such that the angular frequency of the orbit is $\Omega = 8.354\times 10^{-4}$ and the critical energy $E_{\rm crit} = -7.469\times 10^{-3}$ at T=323790 .

Illustration of the model evolution, moments of the snapshots are marked with dashed lines:

Properties of the clusters:

Cluster Mass $r_{\rm c}$ $r_{\rm h}$ $r_{\rm J}$
1 0.975$5.25\times 10^{-3}$ 1.143 77.3
2 0.953$8.61\times 10^{-3}$ 1.334 76.6
3 0.238$0.199$ 6.871 48.3
tests/collision/mock_data/challenge_1.txt · Last modified: 2016/12/16 13:54 by v.henault-brunet