Testing generalized logotropic models with cosmic growth

Boshkayev K. Konysbayev T. Luongo O. Muccino M. Pace F.
15 July 2021 American Physical Society

Physical Review D
2021 #104 Issue 2

We check the dynamical and observational features of four typologies of logotropic dark energy models, leading to a thermodynamic cosmic speed up fueled by a single fluid that unifies dark energy and dark matter. We first present two principal Anton-Schmidt fluids where the Grüneisen parameter is free to vary and then fixed to the special value . We also investigate the pure logotropic model, corresponding to . Finally, we propose a new logotropic paradigm that works as a generalized logotropic fluid, in which we split the role of dark matter and baryons. We demonstrate that the logotropic paradigms may present drawbacks in perturbations, showing a negative adiabatic sound speed which make perturbations unstable. We thus underline which model is favored over the rest. The Anton-Schmidt model with is ruled out while the generalized logotropic fluid seems to be the most suitable one, albeit weakly disfavored than the model. To fix numerical constraints, we combine low- and higher-redshift domains through experimental fits based on Monte Carlo Markov Chain procedures, taking into account the most recent Pantheon supernovae Ia catalog, Hubble measurements, and data points based on the linear growth function for the large scale structures. We also consider two model selection criteria to infer the statistical significance of the four models under examination. We conclude there is a statistical advantage to handle the Anton-Schmidt fluid with the Grüneisen parameter free to vary and/or fixed to . The generalized logotropic fluid indicates suitable results, more statistically favored than the other models until the sound speed is positive, becoming unstable in perturbations elsewhere. We emphasize that the paradigm works statistically better than any kind of logotropic and generalized logotropic models, while the Chevallier-Polarski-Linder parametrization is statistically comparable with logotropic scenarios. Finally, we propose that generalizing the Grüneisen parameter by including the effects of temperature would guarantee the sound speed to be positive definite at all redshifts.

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National Nanotechnology Laboratory of Open Type, Al-Farabi Kazakh National University, Al-Farabi av. 71, Almaty, 050040, Kazakhstan
Department of Physics, Nazarbayev University, Nur-Sultan, 010000, Kazakhstan
Department of Engineering Physics, Satbayev University, 22 Satbayev str., Almaty, 050013, Kazakhstan
Dipartimento di Matematica, Università di Pisa, Largo B. Pontecorvo 5, Pisa, 56127, Italy
Divisione di Fisica, Università di Camerino, Via Madonna delle Carceri, 9, Camerino, 62032, Italy
INFN, Laboratori Nazionali di Frascati, Via Enrico Fermi, 54, Frascati (, 00044, RM, Italy
Dipartimento di Fisica ed Astronomia “, Alma Mater Studiorum Università, di Bologna, Via Gobetti 93/2, Bologna, I-40129, Italy
Jodrell Bank Centre for Astrophysics, School of Natural Sciences, University of Manchester, Alan Turing Building, Oxford Road, Manchester, M13 9PL, United Kingdom

National Nanotechnology Laboratory of Open Type
Department of Physics
Department of Engineering Physics
Dipartimento di Matematica
Divisione di Fisica
INFN
Dipartimento di Fisica ed Astronomia “
Jodrell Bank Centre for Astrophysics

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