COLIBRE: calibrating subgrid feedback in cosmological simulations that include a cold gas phase

Chaikin, E, Schaye, J, Schaller, M, Ploeckinger, S, Bahé, YM, Benítez-Llambay, A, Correa, C, Moreno, VJF, Frenk, CS, Huško, F, Kugel, R, McGibbon, R, Richings, AJ, Trayford, JW, Borrow, J, Crain, RA ORCID: 0000-0001-6258-0344, Helly, JC, Lacey, CG, Ludlow, A and Nobels, FSJ (2026) COLIBRE: calibrating subgrid feedback in cosmological simulations that include a cold gas phase. Monthly Notices of the Royal Astronomical Society, 548 (1). ISSN 0035-8711

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Abstract

We present the calibration of stellar and active galactic nucleus (AGN) feedback in the subgrid model for the new colibre hydrodynamical simulations of galaxy formation. colibre directly simulates the multiphase interstellar medium and the evolution of dust grains, which is coupled to the chemistry. colibre is calibrated at three resolutions: particle masses of m gas ≈ m dm ∼ 10 7 (m7), 10 6 (m6), and 10 5 M (m5). To calibrate the colibre feedback at m7 resolution, we run Latin hypercubes of ≈ 200 simulations that vary up to four subgrid parameters in cosmological volumes of ( 50 cMpc ) 3 . We train Gaussian process emulators on these simulations to predict the z = 0 galaxy stellar mass function (GSMF) and size–stellar mass relation (SSMR) as functions of the model parameters, which we then fit to observations. The trained emulators not only provide the best-fitting parameter values but also enable us to investigate how different aspects of the prescriptions for supernova and AGN feedback affect the predictions. In particular, w e demonstrat e that while the observed z = 0 GSMF and SSMR can be matched individually with a relatively simple supernova feedback model, simultaneously r epr oducing both necessitates a more sophisticated prescription. We show that the calibrated m7 colibre model not only r epr oduces the calibration target observables, but also matches various other galaxy properties to which the model was not calibrated. Finally, we apply the calibrated m7 model to the m6 and m5 resolutions and, after slight manual adjustments of the subgrid paramet ers, achiev e a similar lev el of agreement with the observ ed z = 0 GSMF and SSMR.

Item Type:	Article
Uncontrolled Keywords:	galaxies: evolution; galaxies: formation; galaxies: general; methods: numerical; methods: numerical; galaxies: general; galaxies: formation; galaxies: evolution; 5109 Space Sciences; 51 Physical Sciences; 5107 Particle and High Energy Physics; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	3 February 2026
Date of first compliant Open Access:	24 April 2026
Date Deposited:	24 Apr 2026 15:23
Last Modified:	24 Apr 2026 15:23
DOI or ID number:	10.1093/mnras/stag300
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28452

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