# International conference PUMA22 Probing the Universe with Multimessenger Astrophysics

Sep 26 – 30, 2022
Sestri Levante
Europe/Rome timezone

## Fast emulation of two-point angular statistics for photometric galaxy surveys

Sep 28, 2022, 12:00 PM
20m
Sestri Levante

#### Sestri Levante

Grand Hotel dei Castelli, Via Penisola Levante, 26, 16039 Sestri Levante (GE), Italy
Oral contribution

### Speaker

Biggio Luca (ETH Zurich)

### Description

We develop a set of machine-learning based cosmological emulators, to obtain fast model predictions for the C(ℓ) angular power spectrum coefficients characterising tomographic observations of galaxy clustering and weak gravitational lensing from multi-band photometric surveys (and their cross-correlation). A set of neural networks are trained to map cosmological parameters into the coefficients, achieving a speed-up O($10^3$) in computing the required statistics for a given set of cosmological parameters, with respect to standard Boltzmann solvers, with an accuracy better than 0.175% (<0.1% for the weak lensing case). This corresponds to ∼2% or less of the statistical error bars expected from a typical Stage IV photometric surveys. Such overall improvement in speed and accuracy is obtained through (i) a specific pre-processing optimisation, ahead of the training phase, and (ii) a more effective neural network architecture, compared to previous implementations.

### Primary author

Biggio Luca (ETH Zurich)