Behavior of interacting Ricci dark energy in logarithmic f(T) gravity

Journal of Theoretical and Applied Physics, Sep 2013

In the present work, we have considered a modified gravity model dubbed as ‘logarithmic f(T) gravity’ as reported by Bamba et al. (J. Cosmol. Astropart. Phys 1101:21, 2011) and investigated the behavior of Ricci dark energy interacting with pressureless Dark Matter. We have chosen the interaction term in the form Q=3H δ ρ m and investigated the behavior of the Hubble parameter H as a function of the redshift z. For this reconstructed H, we have investigated the behavior of the fractional density contribution due to the Ricci dark energy and torsion. Subsequently, we investigated the equation of state parameter wRDE which is found to have a phantom-like behavior for all choices of c2 in the Ricci dark energy density. PACS 98.80.-k;95.36.+x;04.50.Kd

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Behavior of interacting Ricci dark energy in logarithmic f(T) gravity

Journal of Theoretical and Applied Physics Behavior of interacting Ricci dark energy in logarithmic f (T ) gravity Rahul Ghosh 0 Antonio Pasqua 2 Surajit Chattopadhyay 1 0 Department of Mathematics, Bhairab Ganguly College , Kolkata 700 056 , India 1 Pailan College of Management and Technology , Bengal Pailan Park, Kolkata 700 104 , India 2 Department of Physics, University of Trieste , Via Valerio 2, Trieste 34127 , Italy In the present work, we have considered a modified gravity model dubbed as 'logarithmic f (T ) gravity' as reported by Bamba et al. (J. Cosmol. Astropart. Phys 1101:21, 2011) and investigated the behavior of Ricci dark energy interacting with pressureless Dark Matter. We have chosen the interaction term in the form Q = 3Hδρm and investigated the behavior of the Hubble parameter H as a function of the redshift z. For this reconstructed H, we have investigated the behavior of the fractional density contribution due to the Ricci dark energy and torsion. Subsequently, we investigated the equation of state parameter wRDE which is found to have a phantom-like behavior for all choices of c2 in the Ricci dark energy density. Logarithmic f (T ) gravity; Ricci dark energy; Dark Matter (DM) - Background The accelerated expansion of the universe is well established by the works of [1,2]. The ‘dark energy’ (DE), characterized by negative pressure, is responsible for this cosmic acceleration [3-6]. The importance of modified gravity for late acceleration of the universe has been reviewed by [7,8]. Various modified gravity theories have been proposed so far. These include f (R) [9,10], f (T ) [11-14], f (G) [15,16], Hoˇrava-Lifshitz [17,18], and GaussBonnet [19,20] theories. One of the newest extended theories of gravity is the so-called f (T ) gravity, which is a theory formulated in a spacetime possessing absolute parallelism [12]. Some fundamental aspects of f (T ) theories have been studied in the works of [21] and [22]. In this theory of modified gravity, the teleparallel Lagrangian density described by the torsion scalar T has been promoted to be a function of T, i.e., f (T ), in order to account for the late time cosmic acceleration [23,24]. Some relevant works in f (T ) theory must be mentioned here. Jamil et al. [25] derived the exact solutions of static wormholes in f (T ) modified gravity theory. Jamil et al. [26] investigated the null, weak, strong, and dominant energy conditions in generalized teleparallel gravities. Jamil et al. [27] studied the statefinder parameters {r, s} in f (T ) cosmology. Jamil et al. [28] studied the Noether symmetries of f (T ) cosmology involving matter and DE. Jamil et al. [29] tried to resolve the Dark Matter (DM) problem in the light of f (T ) modified gravity theory, successfully obtaining the flat rotation curves of galaxies containing DM as component. They also obtained the density profile of Dark Matter in galaxies. Jamil et al. [30] studied the interacting DE model in the framework of f (T ) modified gravity theory for a particular choice of f (T ). Bamba et al. [31] studied the generalized second law of thermodynamics in the framework of f (T ) modified gravity. Models of DE include quintessence [32], quintom [33], phantom [34], Chaplygin gas [35], tachyon [36], h-essence [37], etc. Other relevant works on models of DE have been recently done. Setare [38] studied the interacting holographic dark energy (HDE) model in non-flat universe. Setare [39] studied the bulk brane interaction in order to obtain the equation of state (EoS) parameter for the HDE model in non-flat universe enclosed by the event horizon. Setare [40] studied the cosmological application of the HDE model in the framework of Brans-Dicke cosmology. Setare et al. [41] considered the HDE model in a nonflat universe from the viewpoint of statefinder parameters. All DE models can be classified according to the behavior of the equation of state parameter wD as follow [33]: (1) Cosmological constant: its EoS parameter is exactly equal to −1, that is, wDE = −1; (2) Quintessence: its EoS parameter remains above the cosmological constant boundary, that is, wDE ≥ −1; (3) Phantom: its EoS parameter lies below the cosmological constant boundary, that is, wDE ≤ −1; and (4) Quintom: its EoS parameter is able to evolve across the cosmological constant boundary. Inspired by the holographic principle [42,43], a new model of DE, dubbed as Holographic DE (HDE), has been recently proposed and studied. Recently, Gao et al. [44] proposed the Ricci scalar curvature as infrared cutoff of the system; this model is now known as Ricci dark energy (RDE) model. With a proper choice of parameters involved, the equation of state parameter of the RDE model can cross the value −1, so it has a quintom-like behavior [45]. We must remember here that the Ricci scalar curvature for a Friedmann-Robertson-Walker (FRW) universe is given by R = −6 H˙ + 2H2 + ak2 , where H is the Hubble parameter, a is the scale factor, (...truncated)


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Rahul Ghosh, Antonio Pasqua, Surajit Chattopadhyay. Behavior of interacting Ricci dark energy in logarithmic f(T) gravity, Journal of Theoretical and Applied Physics, 2013, pp. 48, Volume 7, Issue 1, DOI: 10.1186/2251-7235-7-48