Ananke: Gaia on FIRE
The Ananke framework (Sanderson et al 2019) generates realistic synthetic stellar surveys from cosmological baryonic simulations. We have used Ananke to create a set of synthetic phase-space surveys designed to resemble Data Release 2 of the Gaia astrometric survey from different solar viewpoints in the Latte suite of FIRE-2 simulations of Milky Way-mass galaxies. Sanderson et al 2019 describes these synthetic surveys in detail.
Access the synthetic surveys on yt-hub: ananke.hub.yt
RGB flux map in galactic coordinates (|b|<50) of a synthetic survey of the FIRE-2 simulated galaxy m12f. Total flux in each of the three Gaia passbands was assigned to a different color channel, and the resulting image was median-filtered to diminish the effect of “hot” pixels caused by nearby stars.
We generated 3 synthetic surveys (each using different solar positions) from each of 3 Latte simulations, for a total of 9 synthetic surveys.
Each synthetic Gaia DR2-like survey features:
- Cosmological formation histories with self-consistent dark-matter and gas accretion, satellite galaxies, and tidal streams/shells.
- Spatially resolved stellar populations and young star clusters in realistically thin and dynamically complex star-forming disks. The Latte simulations provide sufficient resolution to model kinematically cold, single-age, mono-abundance stellar populations at mass resolution ~5000 Msun at z = 0, comparable to (massive) star clusters. Furthermore, the gas spatial resolution (as small as 1 pc) and temperature range (as cold as 10 K) resolve the formation of giant molecular clouds (GMCs) and the clustered formation of young stars inside of them.
- Complete stellar populations synthesized using a Kroupa stellar initial mass function (IMF) and PARSEC model stellar isochrones.
- Self-consistent dust extinction calculated using a constant dust-to-metals ratio, documented for easy adaptation to other extinction models. This provides realistic correlations between (young) stars and gas, including dust extinction near star-forming regions.
- Simulated Gaia DR2-like uncertainties based on survey averages, with intrinsic values provided for use with more sophisticated error models.
The result is a self-consistent, dust-extincted synthetic survey of each simulated galaxy that leaves intact important observational relationships between gas, dust extinction, stellar populations, and dark matter.
Coming Soon: access through the NASA/IPAC Infrared Science Archive
| Quantity | Explanation | Data type | Unit |
|---|---|---|---|
| Fields with names identical to those in DR2 | |||
| Indices | |||
| source_id | Unique source identifier (per mock catalog) | long | |
| random_index | Random index used to select subsets | long | |
| Astrometry | |||
| ra | Right ascension | double | Angle (deg) |
| ra_error | Standard error of right ascension | double | Angle (deg) |
| dec | Declination | double | Angle (deg) |
| dec_error | Standard error of declination | double | Angle (deg) |
| parallax | Parallax | double | Angle (mas) |
| parallax_error | Standard error of parallax | double | Angle (mas) |
| parallax_over_error | Parallax divided by its error | float | |
| pmra | Proper motion in RA direction | double | Angular Velocity (mas/year) |
| pmra_error | Standard error of proper motion in RA direction | double | Angular Velocity (mas/year) |
| pmdec | Proper motion in declination direction | double | Angular Velocity (mas/year) |
| pmdec_error | Standard error of proper motion in declination direction | double | Angular Velocity (mas/year) |
| l | Galactic longitude (converted from RA, dec) | double | Angle (deg) |
| b | Galactic latitude (converted from RA, dec) | double | Angle (deg) |
| Photometry | |||
| phot_g_mean_mag | Extincted apparent G-band mean magnitude | float | Magnitude (mag) |
| phot_g_mean_mag_error | Standard error of G-band mean magnitude | float | Magnitude (mag) |
| phot_bp_mean_mag | Extincted apparent GBp-band mean magnitude | float | Magnitude (mag) |
| phot_bp_mean_mag_error | Standard error of GBp-band mean magnitude | float | Magnitude (mag) |
| phot_rp_mean_mag | Extincted apparent GRp band mean magnitude | float | Magnitude (mag) |
| phot_rp_mean_mag_error | Standard error of GRp-band mean magnitude | float | Magnitude (mag) |
| bp_rp | Reddened GBp–GRp colour | float | Magnitude (mag) |
| bp_g | Reddened GBp–G colour | float | Magnitude (mag) |
| g_rp | Reddened G–GRp colour | float | Magnitude (mag) |
| a_g_val | line-of-sight extinction in the G band, AG | float | Magnitude (mag) |
| e_bp_min_rp_val | line-of-sight reddening E(GBp-GRp) | float | Magnitude (mag) |
| Spectroscopy | |||
| radial_velocity | Radial velocity | double | Velocity (km/s) |
| radial_velocity_error | Standard error of radial velocity a | double | Velocity (km/s) |
| Stellar Parametersb | |||
| teff_val | Stellar effective temperature | float | Temperature (K) |
| lum_val | Stellar luminosity | float | Luminosity (LSun) |
| Other fields not in the Gaia DR2 data model | |||
| Indices | |||
| parentid | array index of the generating star particle in the snapshot file | long | |
| partid | 0 if phase-space coordinates are identical to the generating star particle, 1 otherwise | short | |
| Phase space | |||
| ra_true | true ra | double | Angle (deg) |
| dec_true | true dec | double | Angle (deg) |
| rad_true | true LSR-centric distance | double | Distance (kpc) |
| dmod_true | true distance modulus | double | Magnitude (mag) |
| parallax_true | true parallax | double | Angle (mas) |
| pmra_true | true pm in ra direction | double | Angular Velocity (mas/yr) |
| pmdec_true | true pm in dec direction | double | Angular Velocity (mas/yr) |
| radial_velocity_true | true RV | double | Velocity (km/s) |
| l_true | true Galactic long | double | Angle (deg) |
| b_true | true Galactic lat | double | Angle (deg) |
| px_true, py_true, pz_true | true position relative to LSRc | double | Distance(kpc) |
| vx_true, vy_true, vz_true | true velocity relative to LSRc | double | Velocity (km/s) |
| Photometry | |||
| phot_g_mean_mag_true | true (i.e. after extinction, but before error convolution) apparent G-band mean magnitude | float | Magnitude (mag) |
| phot_bp_mean_mag_true | true apparent GBp-band mean magnitude | float | Magnitude (mag) |
| phot_rp_mean_mag_true | true apparent GRp-band mean magnitude | float | Magnitude (mag) |
| bp_rp_true | true GBp–GRp colour | float | Magnitude (mag) |
| bp_g_true | true GBp– G colour | float | Magnitude (mag) |
| g_rp_true | true G –GRp colour | float | Magnitude (mag) |
| phot_g_mean_mag_int | intrinsic (i.e. before extinction or error convolution) apparent G-band magnitude | float | Magnitude (mag) |
| phot_bp_mean_mag_int | intrinsic apparent GBp-band mean magnitude | float | Magnitude (mag) |
| phot_rp_mean_mag_int | intrinsic apparent GRp-band mean magnitude | float | Magnitude (mag) |
| bp_rp_int | intrinsic GBp–GRp color | float | Magnitude (mag) |
| bp_g_int | intrinsic GBp– G color | float | Magnitude (mag) |
| g_rp_int | intrinsic G-GRp color | float | Magnitude (mag) |
| Extinction | |||
| lognh | log10 equivalent H column density along line of sight to star | float | cm-2 |
| ebv | E(B-V) reddening, calculated from equivalent NH | float | Magnitude (mag) |
| A0 | A0, extinction at 550 nm, assuming RV=3.1 | float | Magnitude (mag) |
| Stellar Parameters | |||
| mact | current stellar mass | float | Mass (Solar Mass) |
| mtip | mass of a star at tip of giant branch for given age, metallicityd | float | Mass (Solar Mass) |
| mini | stellar mass on zero-age main sequence | float | Mass (Solar Mass) |
| age | log10 stellar age; identical for all stars generated from the same particle | float | Time (log yr) |
| logg | surface gravity | float | Surface Gravity (log cgs) |
| Abundancese | |||
| feh | [Fe/H] | float | Abundances (dex) |
| alpha | [Mg/Fe] | float | Abundances (dex) |
| carbon | [C/H] | float | Abundances (dex) |
| helium | [He/H] | float | Abundances (dex) |
| nitrogen | [N/H] | float | Abundances (dex) |
| sulphur | [S/H] | float | Abundances (dex) |
| oxygen | [O/H] | float | Abundances (dex) |
| silicon | [Si/H] | float | Abundances (dex) |
| calcium | [Ca/H] | float | Abundances (dex) |
| magnesium | [Mg/H] | float | Abundances (dex) |
| neon | [Ne/H] | float | Abundances (dex) |
a. constant noise floor of 0.11 km/s added in quadrature
b. not error-convolved
c. see Sanderson et al. 2018 for a discussion of the coordinate systems
d. evolved stars are those with mact > mtip
e. all relative to solar; identical for all stars generated from the same particle.