caa a22 4500 467887780 CHVBK 20180406152739.0 cr unu---uuuuu 170328e20060501xx s 000 0 eng 10.1007/s10714-006-0261-x doi (NATIONALLICENCE)springer-10.1007/s10714-006-0261-x f ( R ) theories of gravity in the Palatini approach matched with observations [Elektronische Daten] [S. Capozziello, V. Cardone, M. Francaviglia] We investigate the viability of f(R) theories in the framework of the Palatini approach as solutions to the problem of the observed accelerated expansion of the universe. Two physically motivated popular choices for f(R) are considered,: power law, f(R) = β R n , and logarithmic, f(R) = α ln R. Under the Palatini approach, both Lagrangians give rise to cosmological models comprising only standard matter and undergoing a present phase of accelerated expansion. We use the Hubble diagram of type Ia Supernovae and the data on the gas mass fraction in relaxed galaxy clusters to see whether these models are able to reproduce what is observed and to constrain their parameters. It turns out that they are indeed able to fit the data with values of the Hubble constant and of the matter density parameter in agreement with some model independent estimates, but the today deceleration parameter is higher than what is measured in the concordance ΛCDM model. Springer Science and Business Media Inc., New York, 2006 Higher order theories of gravity nationallicence Palatini approach nationallicence Observational cosmology nationallicence Capozziello S. Dipartimento di Scienze Fisiche, Università di Napoli "Federico II,” and INFN, Sez. di Napoli, Compl.,via Cinthia Univ. Monte S. Angelo, Ed. N, 80121, Napoli, Italy aut Cardone V. Dipartimento di Fisica "E.R. Caianiello,”, Università di Salerno and INFN, Sez. di Napoli, Gruppo Coll. di Salerno via S. Allende, 84081-Baronissi, (Salerno), Italy aut Francaviglia M. Dipartimento di Matematica, Università di Torino Via C. Alberto 10, 10123, Torino, Italy aut General Relativity and Gravitation Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 38/5(2006-05-01), 711-734 0001-7701 38:5<711 2006 38 10714 https://doi.org/10.1007/s10714-006-0261-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10714-006-0261-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Capozziello S. Dipartimento di Scienze Fisiche, Università di Napoli "Federico II,” and INFN, Sez. di Napoli, Compl.,via Cinthia Univ. Monte S. Angelo, Ed. N, 80121, Napoli, Italy aut NATIONALLICENCE 700 1- Cardone V. Dipartimento di Fisica "E.R. Caianiello,”, Università di Salerno and INFN, Sez. di Napoli, Gruppo Coll. di Salerno via S. Allende, 84081-Baronissi, (Salerno), Italy aut NATIONALLICENCE 700 1- Francaviglia M. Dipartimento di Matematica, Università di Torino Via C. Alberto 10, 10123, Torino, Italy aut NATIONALLICENCE 773 0- General Relativity and Gravitation Kluwer Academic Publishers-Plenum Publishers; http://www.springer-ny.com 38/5(2006-05-01), 711-734 0001-7701 38:5<711 2006 38 10714 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer