Cosmological constrains on new generalized Chaplygin gas model
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Cosmological constrains on new generalized Chaplygin gas model Fataneh Salahedin1, Reza Pazhouhesh1,a
, Mohammad Malekjani2
1 Department of Physics, Faculty of Sciences, University of Birjand, Birjand, Iran 2 Department of Physics, Bu-Ali Sina University, Hamedan 65178, Iran
Received: 17 March 2020 / Accepted: 29 April 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract We use different combinations of data samples to investigate the new generalized Chaplygin gas (NGCG) model in the context of dark energy (DE) cosmology. Using the available cosmological data, we put constraints on the the free parameters of NGCG model based on the statistical Markov chain Monte Carlo method. We then find the best fit values of cosmological parameters and those confidence regions in NGCG cosmology. Our result for the matter density parameter calculated in NGCG model is in excellent agreement with that of the standard CDM cosmology. We also find that the equation of state of DE of the model slightly favors the phantom regime. We show that the big tension between the lowand high-redshift observations appearing in CDM universe to predict the Hubble constant H0 can be alleviated in NGCG model. However, from the statistical point of view, our results show that the standard CDM model fits the observations better than the NGCG cosmology.
1 Introduction The analysis of various observational data, including those of cosmic microwave background (CMB) [1,2], supernovae type Ia (SNIa) [3,4], large-scale structures (LSS), baryon acoustic oscillation (BAO) [5] and other cosmic observations strongly suggest that the present universe is undergoing an accelerated phase of expansion. In order to explain this acceleration, an unknown component with negative pressure the so-called dark energy (DE) was proposed [6]. The earliest and simplest model for DE is the cosmological standard [7] with constant equation of state (EoS) parameter equal to −1. This model can successfully describe observations, while it indeed encounters some of theoretical problems; for example the coincidence and fine-tuning problems [8,9]. Therefore, some of other DE models have been proposed in the literature, such as quintessence [10], phantom [11,12], holographic [13], oscillating Quintom [14], agegraphic [15] and Ghost [16]. Although these models can solve or alleviate the problems of CDM, they should be confirmed by the cosmic observations. Many investigations have been done to examine these DE models in the light of observational data (reader can see [17–21]). Besides the DE models, modified gravity theories such as scalar tensor cosmology [22] and braneworld models [23] were proposed to solve the challenge of acceleration of universe.
a e-mail: [email protected] (corresponding author)
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The Chaplygin gas model is a candidate of DE that unifies dark matter and DE. In fact, this model plays a dual role at different epochs
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