Signatures of $f(Q)$-gravity in cosmology
  We investigate the impact on cosmological observables of $f(Q)$-gravity, a
specific class of modified gravity models in which gravity is described by the
non-metricity scalar, $Q$. In particular we focus on a specific model which is
indistinguishable from the $\Lambda$-cold-dark-matter ($\Lambda$CDM) model at
the background level, while showing peculiar and measurable signatures at
linear perturbation level. These are attributed to a time-dependent Planck mass
and are regulated by a single dimensionless parameter, $\alpha$. In comparison
to the $\Lambda$CDM model, we find for positive values of $\alpha$ a suppressed
matter power spectrum and lensing effect on the Cosmic Microwave Background
radiation (CMB) angular power spectrum and an enhanced integrated-Sachs-Wolfe
tail of CMB temperature anisotropies. The opposite behaviors are present when
the $\alpha$ parameter is negative. We also investigate the modified
Gravitational Waves (GWs) propagation and show the prediction of the GWs
luminosity distance compared to the standard electromagnetic one. Finally, we
infer the accuracy on the free parameter of the model with standard sirens at
future GWs detectors.
