### Table of Contents

# Ideas for additional challenges

## Weighing dark remnants using luminous stars

Explore how/if the mass function of dark remnants can be constrained from a limited set of observables, using mock data from N-body simulations. This could be part of Miklos’ project on Challenge 2. Provided that this works, we can then consider a direct application to real data (e.g. Gaia-ESO survey - some of us are members of the consortium).

## Dark remnants & IMBH

Laura is applying her discrete Jeans modelling method to snapshots of N-body models that contain stellar-mass black holes. The idea is check if a concentration of dark remnants near the centre can be mistaken for an intermediate-mass black hole.

## Pal 5 model from Andreas Kuepper in streams section

Same analyses as in Challenge 2 and 3, but with cluster on eccentric orbit and “polluting” stars from tidal tails. The models posted in the streams section were not evolved with stellar evolution and for a Hubble time, but Andreas sent me files for that. Will upload them if there is interest.

## Models with initial rotation

Different models with angular momentum are within the group: collapsing spheres, cold fractal collapse, cluster mergers.

### Collapse of homogeneous spheres with angular momentum

Below snapshots of 3 cold(ish) collapses of homogeneous spheres with angular momentum. Initial virial ratios and angular momentum were taken from the 3 models described in Gott (1972). The models contain 2e5 stars, a Kroupa IMF between 0.1 and 100 Msun and snapshots are at t=30 [NBODY]. The amount of rotation is quantified with Peebles $\lambda$ parameter in the title:

- rot_collapse_lam0.127.gz NEW! Tuesday August 20
- rot_collapse_lam0.168.gz NEW! Tuesday August 20
- rot_collapse_lam0.212.gz NEW! Tuesday August 20

### Mergers

Merger between 2 clusters of equal mass, equal containing 1e5 stars, a Kroupa IMF between 0.1 and 100 Msun. The initial orbit of the cluster pair had zero energy and different angular momentum. The

- rot_merger_lam0.128.gz NEW! Tuesday August 20

For both collapse and mergers collapse contain:

$M$ | $X$ | $Y$ | $Z$ | $V_x$ | $V_y$ | $V_z$ |
---|---|---|---|---|---|---|

[$M_\odot$] | [NBODY] | [NBODY] |

### Collapse of non-homogeneous spheres with angular momentum

(Based on simulations ran by Anna Lisa Varri, see Ref1 Ref2)

Below snapshots of two cold(ish) collapses of isolated spheres with N=64k, equal mass stars, non-homogeneous initial density distribution (fractal dimension D = 2.8, 2.4, as in the file name), and approximate solid-body rotation. The configurations are characterized by the same **initial** values of virial ratio and global angular momentum as in the homogeneous case #3 (with $\lambda=0.212$). The simulations have been performed with STARLAB and the snapshots are taken at T=20 [NBODY].

- rot_collapse_fracd2.4.gz NEW! Tuesday August 20
- rot_collapse_fracd2.8.gz NEW! Tuesday August 20

The file header contains: N, T, coordinates and velocities of the center of mass. The file format is as follow:

$ID$ | $M$ | $X$ | $Y$ | $Z$ | $V_x$ | $V_y$ | $V_z$ |
---|---|---|---|---|---|---|---|

[NBODY] | [NBODY] | [NBODY] |

## Mass modelling multiple-population GC with non-parametric method

Apply Pascal Steger's non-parametric method (developed for dwarf galaxies) to mock data from N-body simulation of globular cluster with two distinct chemical populations.

The data has the following format.

$m$ | $x$ | $y$ | $z$ | $v_x$ | $v_y$ | $v_z$ | population |
---|---|---|---|---|---|---|---|

[Msun] | [pc] | [pc] | [pc] | [km/s] | [km/s] | [km/s] | [1 or 2] |

## More ideas (but no mock data for these yet)

- What is the effect of binary stars?
- Is there a dynamical “smoking gun” for an intermediate mass black hole?