# Data-driven estimation of the invisible energy of cosmic ray showers with the Pierre Auger Observatory

## TL;DR

This paper introduces a new data-driven method to estimate the invisible energy in cosmic ray showers, reducing uncertainties and improving energy measurements at the Pierre Auger Observatory.

## Contribution

A novel approach using ground-level muon measurements to estimate invisible energy, minimizing dependence on primary particle assumptions and interaction models.

## Key findings

- Significantly reduced systematic uncertainties in energy estimation.
- Improved accuracy of cosmic ray energy scale.
- Enhanced understanding of muon production in air showers.

## Abstract

The determination of the primary energy of extensive air showers using the fluorescence detection technique requires an estimation of the energy carried away by particles that do not deposit all their energy in the atmosphere. This estimation is typically made using Monte Carlo simulations and thus depends on the assumed primary particle mass and on model predictions for neutrino and muon production. In this work we present a new method to obtain the invisible energy from events detected by the Pierre Auger Observatory. The method uses measurements of the muon number at ground level, and it allows us to reduce significantly the systematic uncertainties related to the mass composition and the high energy hadronic interaction models, and consequently to improve the estimation of the energy scale of the Observatory.