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We use the latest compilation of observational H(z) measurements obtainedwith cosmic chronometers in the redshift range $0<z<2$ to place constraints oncosmological parameters. We consider the sample alone and in combination withother state-of-the art cosmological probes: CMB data from the latest Planck2015 release, the most recent estimate of the Hubble constant $H_{0}$, acompilation of recent BAO data, and the latest SNe sample. Since cosmicchronometers are independent of the assumed cosmological model, we are able toprovide constraints on the parameters that govern the expansion history of theUniverse in a way that can be used to test cosmological models. We show thatthe H(z) measurements obtained with cosmic chronometer from the BOSS surveyprovide enough constraining power in combination with CMB data to constrain thetime evolution of dark energy, yielding constraints competitive with thoseobtained using SNe and/or BAO. From late-Universe probes alone we find that$w_0=-0.9\pm0.18$ and $w_a=-0.5\pm1.7$, and when combining also CMB data weobtain $w_0=-0.98\pm0.11$and $w_a=-0.30\pm0.4$. These new constraints implythat nearly all quintessence models are disfavoured, only phantom models or apure cosmological constant being allowed. For the curvature we find$\Omega_k=0.003\pm0.003$, including CMB data. Cosmic chronometers data areimportant also to constrain neutrino properties by breaking or reducingdegeneracies with other parameters. We find that $N_{eff}=3.17\pm0.15$, thusexcluding the possibility of an extra (sterile) neutrino at more than$5\sigma$, and put competitive limits on the sum of neutrino masses, $\Sigmam_{\nu}< 0.27$ eV at 95% confidence level. Finally, we constrain the redshiftevolution of dark energy, and find w(z) consistent with the $\Lambda$CDM modelat the 40% level over the entire redshift range $0<z<2$. [abridged]

Constraining the time evolution of dark energy, curvature and neutrino properties with cosmic chronometers