The EAGLE simulations of galaxy formation: Public release of halo and galaxy catalogues

TLDR: A relational database storing a large number of properties of haloes and galaxies and their merger trees, including stellar masses, star formation rates, metallicities, photometric measurements and mock gri images is made available for general use.

About: This article is published in Astronomy and Computing.The article was published on 2016-04-01 and is currently open access. It has received 409 citations till now. The article focuses on the topics: Galaxy formation and evolution & Galaxy.

Figures

Table B.1: – continued. Columns in this table exist for each of three different components: star-forming gas (SF), non-star-forming gas (NSF) and stars (Stars). As these properties are repeated for each of these components, we only describe them once. In the database each property will be preceded with either [SF/NSF/Stars] before its name. For instance, the metallicity field will exist in three variants: SF Metallicity, NSF Metallicity and Stars Metallicity for the metallicity of the star-forming gas, of the non star-forming gas and of the stars, respectively. Any sum used to describe a property is the sum of all particles for that component only.

Figure 1: Mock gri images of a galaxy at z = 0.1 as available in the database. The left, central and right panels correspond to the Image face, Image edge and Image box views (in the database nomenclature) of the same simulated galaxy (GalaxyID = 16116800 in the Ref-L0100N1504 simulation). The images are 60 pkpc on a side. Note the clear presence of a bulge, of dust absorption and of spiral arms.

Table B.3: Full listing of the content of the galaxy sizes table and description of the columns. These properties are contained in tables denoted [modelname] Sizes. This table contains half-mass sizes of the stellar component of galaxies using spherical apertures (Furlong et al. (in prep.). The GalaxyID column can be used to join this table to the corresponding [modelname] SubHalo table. Only galaxies with total stellar mass M∗ > 108 M have entries in this table.

Table B.2: Full listing of the content of the halo table and description of the columns. These properties are contained in tables denoted [modelname] FOF. This table can be linked to the [modelname] SubHalo table using the unique GroupID identifier.

Table 2: sql tables available for each simulation. The tables are prefixed with the name of the simulation to which they correspond. For example, the table of magnitudes for the 50 Mpc Ref- model is labelled RefL0050N0752 Magnitudes as can be seen on Figure 3.

Table B.5: Full listing of the content of the magnitudes table and description of the columns. These properties are contained in tables denoted [modelname] Magnitudes. This table contains absolute rest-frame magnitudes without dust attenuation for all galaxies with M∗ > 108.5 M contained in the SubHalo table. This table can be joined to the SubHalo table using the GalaxyID field. The magnitudes in the different SDSS (Doi et al., 2010) and UKIRT (Hewett et al., 2006) filters have been computed in 30 pkpc spherical apertures following the procedure described by Trayford et al. (2015).

Frequently asked questions

Q1. How many square field of view is used for observations in the SDSS gri bands?

A square field of view of 60 pkpc on a side is used for observations in the SDSS gri bands (Doi et al., 2010), with the galaxy spectra red-shifted to z = 0.1 to approximate SDSS colours. 

Q2. What is the main advantage of the eagle database?

The database allows multiple indexing of the data that significantly enhances access speed and allows the selection of smaller data subsets that can be quickly analysed using simple scripting languages. 

Q3. What is the main purpose of the simulations?

The simulations include subgrid formulations to account for processes that cannot be directly resolved in the calculation and that describe how stars and black holes form and impact the matter distribution around them. 

Q4. What is the purpose of this paper?

The aim of this paper is to introduce and make available a relational database that can be queried using the Structured Query Language (sql) to explore and exploit the halo and galaxy catalogues of the main eagle simulations. 

Q5. What are the main points of the paper presenting eagle?

The papers presenting eagle have shown that the simulation broadly reproduces a wide set of observational properties of galaxies and the intergalactic medium. 

Q6. How long does it take to join multiple tables?

More complex queries (i.e. joining multiple tables or navigating the merger trees for multiple galaxies at the sametime) can take up to a few seconds. 

Q7. What is the algorithm used to trace subhaloes?

In essence, the algorithm traces subhaloes using the Nlink most bound particles of any species, identifying the subhalo that contains the majority of these particles as a subhalo’s descendant at the next output time. 

Q8. Why is the black hole mass not captured in the database?

due to the coarse time sampling of the outputs, the high temporal variability of the black hole accretion rates cannot be captured in the database outputs and as such the quantity BlackHoleMassAccretionRate should be treated with great care. 

Q9. What is the name of the simulation suite?

The simulation suite was run with a modified version of the gadget-3 Smoothed Particle Hydrodynamics (SPH) code (last described by Springel, 2005), and includes a full treatment of gravity and hydrodynamics. 

Q10. How can a user submit a query to the eagle database?

sql queries can be typed in the main text box (number 1 in the Figure) and are submitted to the database by pressing either of the buttons to the right (number 2).