Speaker
Description
The energy spectrum of ultra-high-energy cosmic rays (UHECRs) above 2.5$\,$EeV is measured over the declination range $-90^\circ$ to $+44.8^\circ$ using 310,000 events from the Pierre Auger Observatory, corresponding to an exposure of $(104{,}900 \pm 3{,}100)\,\mathrm{km}^2\,\mathrm{sr}\,\mathrm{yr}$. The energy spectrum is studied as a function of declination to investigate possible variations across the sky. Within the statistical uncertainties, the spectra are found to be indistinguishable across declinations, after allowing or not for sky non-uniformities induced by the dipolar anisotropies in the arrival directions of ultra-high-energy cosmic rays. The high-statistics dataset enables a precise characterization of spectral features, including the ankle, the suppression at the highest energies, and a distinct ``instep'' feature at $\simeq 10~\mathrm{EeV}$. The instep is established with a significance above $5\sigma$, strengthening previous evidence. The absence of any declination dependence disfavors an interpretation in which the instep arises from a small number of distinctive sources. This presentation focuses on the analysis strategy adopted in this measurement and on some of the implications of these results.
