Cosmological multifield emulator

We demonstrate the use of deep network to learn the distribution of data from state-of-the-art hydrodynamic simulations of the CAMELS project. To this end, we train a generative adversarial network to generate images composed of three different channels that represent gas density (Mgas), neutral hydrogen density (HI), and magnetic field amplitudes (B). We consider an unconstrained model and another scenario where the model is conditioned on the matter density Ω_ m and the amplitude of density fluctuations σ_8. We find that the generated images exhibit great quality which is on a par with that of data, visually. Quantitatively, we find that our model generates maps whose statistical properties, quantified by probability distribution function of pixel values and auto-power spectra, agree reasonably well with those of the real maps. Moreover, the cross-correlations between fields in all maps produced by the emulator are in good agreement with those of the real images, which indicates that our model generates instances whose maps in all three channels describe the same physical region. Furthermore, a CNN regressor, which has been trained to extract Ω_ m and σ_8 from CAMELS multifield dataset, recovers the cosmology from the maps generated by our conditional model, achieving R^2 = 0.96 and 0.83 corresponding to Ω_ m and σ_8 respectively. This further demonstrates the great capability of the model to mimic CAMELS data. Our model can be useful for generating data that are required to analyze the information from upcoming multi-wavelength cosmological surveys.