User Tools

Site Tools


This is an old revision of the document!

Mock data for the 5th Gaia Challenge (dwarf spheroidals and globular clusters)


We have mocks for:

  1. Globular clusters (distance 5 kpc, max angular radius 1 deg):
  2. Dwarf spheroidal galaxies (distance 70 kpc, max angular radius 0.5 deg)

Both objects are assumed to have quasi-Plummer stellar density profiles, that is Plummer profiles with inner slope –0.1 and outer slope –5.
The mock globular clusters have no dark matter and no mass segregation in the stars. They can contain central intermediate-mass black holes.
The mock dwarf spheroidals are embedded in a dark matter halo, the stars contribute negligibly to the mass, and there is no central black hole.

Physical mocks

We will use different physical situations for the mock data:

  1. DF: Single-component spherical models based on distribution functions.
  2. 2-comp: Two-component spherical models (dwarf spheroidals only).
  3. Stripped: Output of an N-body run of a system orbiting a Milky Way potential on an orbit with apocenter/pericenter ratio of 3.4, fairly typical of isotropic systems. See Justin Read's explanations of tidally stripped models.

These mocks (except for the globular cluster DF mocks) were created in the 3rd Gaia Challenge and are available here. To keep the number of mocks more manageable, we propose to no longer use the NonPlum mocks, which have unrealistically steep inner stellar density profiles.

Astronomical set-ups

For each physical situation, we will use different astronomical set ups:

  1. cart6D: six-dimensional cartesian mock with 2 km/s velocity errors.
  2. GaiaSimple: Gaia mission mocks with 2 km/s errors in line-of-sight (LOS) velocities, equivalent errors in proper motions (PMs), and no field stars.
  3. GaiaDR2errs: Same as GaiaSimple, but with realistic Gaia-DR2 errors
  4. GaiaDR2Full: Same as GaiaDR2errs, but also with field stars
  5. GaiaDR3errs: Same as GaiaDR2errs, but for realistic Gaia-DR4 (not Gaia-DR3!) errors (4.4x less than Gaia DR2)
  6. GaiaDR3Full: Same as GaiaDR3errs, but also with field stars
  7. Gaia10yrerrs: Same as GaiaDR3errs, but for realistic Gaia-10-year errors (2.8x less than Gaia-DR4)
  8. Gaia10yrFull: Same as Gaia10yrerrs, but also with field stars
  9. Theiaerrs: Same as GaiaDR3errs, but for realistic Theia mission concept errors (65x less than Gaia-DR4)
  10. TheiaFull: Same as Theiaerrs, but also with field stars

For the Gaia mocks, the LOS velocities will have lower errors than from the Gaia RVS instrument, assuming instead equivalently equal errors to the plane-of-sky errors at the distance of the object.

The globular clusters will have mocks for all astronomical set ups, except Theia.
The dwarf spheroidals will have mocks for all astronomical set ups, except Gaia DR2.

The output formats are:

  • cart6D: x, y, z, v_x, v_y, v_z, with positions in kpc and velocities in km/s.
  • Gaia/Theia: RA, Dec, PM_RA, err(PM_RA), PM_Dec, err(PM_Dec), v_LOS, err(v_LOS), with coordinates in decimal degrees, PMs in mas/yr and LOS velocities in km/s. Files with realistic velocity errors have a final column providing apparent magnitude.

The detailed explanation of how Gary Mamon built the Gaia/Theia mocks is given here.

Variations per mock

For each physical/astronomical setup, we have files with 1000 or 10000 system velocities (even 100000 system velocities for GCs), plus possible additional field stars. You are encouraged to run your models on the first 5 mocks of 1000 and on the mock of 10000. For the cart6D mocks, we propose to only analyze those using the z axis for the LOS.

Modeling modes

You are encouraged to run your models on these mocks, both in LOS-only mode and in LOS+PM mode. And to be fair, you should assume radial profiles of stellar density, mass density and stellar velocity anisotropy that are either non-parametric or parametrized with the correct general shape, but with free inner and outer slopes (for densities) or anisotropies, and free scales (for the stellar and mass densities and for the velocity anisotropy).

You can find the mocks at these locations:

  • here for the dSph cart6D ones (2.4 MB, ASCII)
  • here for the dSph Gaia-like and the standard GC mocks (290 MB .tar.gz file, CSV) [new: added magnitudes in last column (except for cart6D and GaiaSimple)]
  • here for the GC mocks with possible rotation (268 MB .tar.gz file, CSV)

If you previously worked this summer with ASCII files for GCs found on this site, please start again with the CSV files (debugged, and the CSV output is easier to read in TopCat).

Back to 5th Gaia Challenge home page

gc5_mocks.1571250800.txt.gz · Last modified: 2019/10/16 18:33 by gmamon