EAGLE takes off

The first EAGLE paper is now available on the astro-ph archive. It will tell you everything you wanted to know about the project (and more probably more!).  Most importantly, it sets out the project philosophy and shows just how much the simulated universe looks like the real one.

mf_hydro_comp

This plot counts the numbers of galaxies of different masses. It compares the main Eagle simulation (the dark blue line) to previous work (the other lines) and observational data (the fray points)… you’re meant to see that EAGLE fits the data really well – it captures both the flat part (similar numbers of galaxies with masses to our Milky Way galaxy and with mass 10 times smaller), and the exponential break at higher masses (galaxies much larger than our own are incredibly rare). EAGLE is a huge step forward compared to previous work. There are many more comparisons like this in the paper.

Here’s the paper’s abstract….

We introduce the Virgo Consortium’s EAGLE project, a suite of hydrodynamical simulations that follow the formation of galaxies and black holes in representative volumes. We discuss the limitations of such simulations in light of their finite resolution and poorly constrained subgrid physics, and how these affect their predictive power. One major improvement is our treatment of feedback from massive stars and AGN in which thermal energy is injected into the gas without the need to turn off cooling or hydrodynamical forces, allowing winds to develop without predetermined speed or mass loading factors. Because the feedback efficiencies cannot be predicted from first principles, we calibrate them to the z~0 galaxy stellar mass function and the amplitude of the galaxy-central black hole mass relation, also taking galaxy sizes into account. The observed galaxy mass function is reproduced to 0.2 dex over the full mass range, 108<M/M1011, a level of agreement close to that attained by semi-analytic models, and unprecedented for hydrodynamical simulations. We compare our results to a representative set of low-redshift observables not considered in the calibration, and find good agreement with the observed galaxy specific star formation rates, passive fractions, Tully-Fisher relation, total stellar luminosities of galaxy clusters, and column density distributions of intergalactic CIV and OVI. While the mass-metallicity relations for gas and stars are consistent with observations for M109M, they are insufficiently steep at lower masses. The gas fractions and temperatures are too high for clusters of galaxies, but for groups these discrepancies can be resolved by adopting a higher heating temperature in the subgrid prescription for AGN feedback. EAGLE constitutes a valuable new resource for studies of galaxy formation.

 

 

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