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The Aquila comparison project : the effects of feedback and numerical methods on simulations of galaxy formation

Scannapieco, C.; Wadepuhl, M.; Parry, O.H.; Navarro, J.F.; Jenkins, A.; Springel, V.; Teyssier, R.; Carlson, E.; Couchman, H.M.P.; Crain, R.A.; Dalla Vecchia, C.; Frenk, C.S.; Kobayashi, C.; Monaco, P.; Murante, G.; Okamoto, T.; Quinn, T.; Schaye, J.; Stinson, G.S.; Theuns, T.; Wadsley, J.; White, S.D.M.; Woods, R.

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C. Scannapieco

M. Wadepuhl

O.H. Parry

J.F. Navarro

V. Springel

R. Teyssier

E. Carlson

H.M.P. Couchman

R.A. Crain

C. Dalla Vecchia

C. Kobayashi

P. Monaco

G. Murante

T. Okamoto

T. Quinn

J. Schaye

G.S. Stinson

T. Theuns

J. Wadsley

S.D.M. White

R. Woods


We compare the results of various cosmological gas-dynamical codes used to simulate the formation of a galaxy in the Λ cold dark matter structure formation paradigm. The various runs (13 in total) differ in their numerical hydrodynamical treatment [smoothed particle hydrodynamics (SPH), moving mesh and adaptive mesh refinement] but share the same initial conditions and adopt in each case their latest published model of gas cooling, star formation and feedback. Despite the common halo assembly history, we find large code-to-code variations in the stellar mass, size, morphology and gas content of the galaxy at z= 0, due mainly to the different implementations of star formation and feedback. Compared with observation, most codes tend to produce an overly massive galaxy, smaller and less gas rich than typical spirals, with a massive bulge and a declining rotation curve. A stellar disc is discernible in most simulations, although its prominence varies widely from code to code. There is a well-defined trend between the effects of feedback and the severity of the disagreement with observed spirals. In general, models that are more effective at limiting the baryonic mass of the galaxy come closer to matching observed galaxy scaling laws, but often to the detriment of the disc component. Although numerical convergence is not particularly good for any of the codes, our conclusions hold at two different numerical resolutions. Some differences can also be traced to the different numerical techniques; for example, more gas seems able to cool and become available for star formation in grid-based codes than in SPH. However, this effect is small compared to the variations induced by different feedback prescriptions. We conclude that state-of-the-art simulations cannot yet uniquely predict the properties of the baryonic component of a galaxy, even when the assembly history of its host halo is fully specified. Developing feedback algorithms that can effectively regulate the mass of a galaxy without hindering the formation of high angular momentum stellar discs remains a challenge.


Scannapieco, C., Wadepuhl, M., Parry, O., Navarro, J., Jenkins, A., Springel, V., …Woods, R. (2012). The Aquila comparison project : the effects of feedback and numerical methods on simulations of galaxy formation. Monthly Notices of the Royal Astronomical Society, 423(2), 1726-1749.

Journal Article Type Article
Publication Date Jun 21, 2012
Deposit Date Mar 4, 2013
Publicly Available Date Aug 22, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 423
Issue 2
Pages 1726-1749
Keywords Methods: numerical, Galaxies: evolution, Galaxies: formation, Cosmology: theory.


Published Journal Article (19.3 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS Published by Oxford University Press on behalf of Royal Astronomical Society. All rights reserved.

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