Contents lists available at ScienceDirect New Astronomy journal homepage: www.elsevier.com/locate/newast Tsallis HDE with an IR cutof as Ricci horizon in a fat FLRW universe Umesh Kumar Sharma ⁎ ,a , Vandna Srivastava b a Department of Mathematics, Institute of Applied Sciences and Humanities, GLA University Mathura-281406, UP, India b Department of Mathematics, Applied Sciences, MIET, Meerut-250005, UP, India ARTICLE INFO Keywords: Phantom Quintessence k-essence THDE PACS: 98.80.-k ABSTRACT The THDE (Tsallis HDE) model using an IR cut of as Ricci horizon has been investigated in the context of a fat Friedmann-Lema ^ tre-Robertson-Walker Universe by describing an accelerated expansion stage which Universe is experiencing. Evolution of Universe from decelerated (earlier) to the accelerated (current) phase exhibits by deceleration parameter (DP) attained in the model of THDE. The good behavior of cosmos is represented by Tsallis parameter δ and the EoS parameter’s values as phantom era ( < 1 T ) and the quintessence era ( 1 T ). Stability of the THDE model has been suggested by squared sound speed v s 2 . Additionally, for the THDE model the relation between phantom, quintessence and k-essence scalar felds has been analysed which helps to annotate the accelerated phase of the expanded Universe. 1. Introduction Diferent observations (like measurements of CMB temperature and polarization anisotropies from the Planck satellite, SNeIa luminosity distance measurements and measurements of the clustering of the LSS) from diferent survey provide a noteworthy description of the Universe Aghanim (2018); Scolnicv (2018); Alam (2017). These observations are pointing to ΛCDM model which describes the spatially fat Universe comprising of two dark components :- Dark Energy (DE) and Dark Matter (DM) Sahni (2004). DE represents about 70% of the total energy consist of a component which is known for its numerousness and stand responsible for the acceleration of the current scenario of expanded Universe and about 5% baryons (the visible matter). Remaining about 25% is associated to DM. Although the nature and cosmological prop- erties are unrevealed but still researchers accepted the dark energy as a key to unveil the lining of Universe. CC-cosmological constant (or the vacuum energy) has been introduced to explain the efects of DE with a constant equation of state (EoS) parameter ω = where vacuum energy plays an important role. With the predictions of ΛCDM model for which observational data are remarkably consistent. Two fundamental pro- blem arises in front of cosmologists: 1- Fine tuning: (required by vacuum energy) which gives the comparison between observational cosmolo- gical constant and fundamental Plank Scale. Fundamental Plank scale is greater than the observed value 10 123 ρ p . 2- Coincidence Problem: Although with the expansion of Universe evolutionary of two densities of DE and DM is diferent but coincidently their amount exists in same magnitude. Requirement of the proportion of DM and DE densities is equal or tending to unity leads to various dynamic dark energy models have been stated in the literature. Some references . Barbieri et al. (2005); Heckman et al. (2019); Higgs (2015); Benisty et al. (2019); Nunes and Pan (2016); Kamenshchik et al. (2001); Freese and Lewis (2002); Hlozek et al. (2015); . Visinelli and Vagnozzi (2019); Ratra and PJE (1988); Peracaula et al. (2018); Wetterich (1988); Bento et al. (2002); Li (2004); PJE and Vilenkin (1999); Caldwell et al. (1998); Capozziello et al. (2018); Benisty and Guendelman (2018); Rinaldi (2015); Cicoli et al. (2012); Di et al. (2020) are included for some recent and infuential approaches to explain DE and cosmic acceleration alternatively which could alle- viate or even solve two problems. On modifying standard HDE as = S A (δ is non-extensive para- meter and γ is a constant). Tsallis HDE Tavayef et al. (2018), a new dark energy model has been recently proposed taking Tsallis entropy as its foundation Tsallis and LJL (2013) and holographic principle(i.e. Finite number of degrees of freedom in a system which is bounded and related to the area of its boundary) and energy density = BL D 2 4 where B is a (not known) parameter and L is an I R cut-of. With the value = 1 and = G 1 4 ( = = = h k c 1 B in units) power-law distribution of probability neutralizes and in the system of the ordinary probability distribution the Bekenstein entropy is recouped Vershynina (2019). In Zadeh et al. (2018a), the researchers investigated the dynamics in both interacting and non-interacting cases in FRW fat Universe. Inside Brans-Dicke gravity theory and Brane cosmology Ghafari et al. (2018, 2019), THDE and its outgrowths with an IR cutof as Hubble horizon is analysed. Sheykhi Sheykhi (2018) by considering an IR cut of to be the https://doi.org/10.1016/j.newast.2020.101519 Received 4 August 2020; Accepted 3 October 2020 ⁎ Corresponding author. E-mail addresses: sharma.umesh@gla.ac.in (U.K. Sharma), vandna.rathor@miet.ac.in (V. Srivastava). New Astronomy 84 (2021) 101519 Available online 09 October 2020 1384-1076/ © 2020 Elsevier B.V. All rights reserved. T