Bayesian deep learning for cosmic volumes with modified gravity
- URL: http://arxiv.org/abs/2309.00612v2
- Date: Mon, 12 Feb 2024 17:15:34 GMT
- Title: Bayesian deep learning for cosmic volumes with modified gravity
- Authors: Jorge Enrique Garc\'ia-Farieta, H\'ector J Hort\'ua and Francisco-Shu
Kitaura
- Abstract summary: This study aims at extracting cosmological parameters from modified gravity (MG) simulations through deep neural networks endowed with uncertainty estimations.
We train both BNNs with real-space density fields and power-spectra from a suite of 2000 dark matter only particle mesh $N$-body simulations.
BNNs excel in accurately predicting parameters for $Omega_m$ and $sigma_8$ and their respective correlation with the MG parameter.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: The new generation of galaxy surveys will provide unprecedented data allowing
us to test gravity at cosmological scales. A robust cosmological analysis of
the large-scale structure demands exploiting the nonlinear information encoded
in the cosmic web. Machine Learning techniques provide such tools, however, do
not provide a priori assessment of uncertainties. This study aims at extracting
cosmological parameters from modified gravity (MG) simulations through deep
neural networks endowed with uncertainty estimations. We implement Bayesian
neural networks (BNNs) with an enriched approximate posterior distribution
considering two cases: one with a single Bayesian last layer (BLL), and another
one with Bayesian layers at all levels (FullB). We train both BNNs with
real-space density fields and power-spectra from a suite of 2000 dark matter
only particle mesh $N$-body simulations including modified gravity models
relying on MG-PICOLA covering 256 $h^{-1}$ Mpc side cubical volumes with
128$^3$ particles. BNNs excel in accurately predicting parameters for
$\Omega_m$ and $\sigma_8$ and their respective correlation with the MG
parameter. We find out that BNNs yield well-calibrated uncertainty estimates
overcoming the over- and under-estimation issues in traditional neural
networks. We observe that the presence of MG parameter leads to a significant
degeneracy with $\sigma_8$ being one of the possible explanations of the poor
MG predictions. Ignoring MG, we obtain a deviation of the relative errors in
$\Omega_m$ and $\sigma_8$ by at least $30\%$. Moreover, we report consistent
results from the density field and power spectra analysis, and comparable
results between BLL and FullB experiments which permits us to save computing
time by a factor of two. This work contributes in setting the path to extract
cosmological parameters from complete small cosmic volumes towards the highly
nonlinear regime.
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