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Four new cosmological quantities were introduced which are the horizon expansion speed, horizon expansion acceleration, horizon volume speed and horizon volume acceleration of the universe expansion. These quantities have been investigated in five general cosmic models. The distributions of the space expansion speed of the universe in these models decrease up to minimum values, then they increase slowly until Gyr, and hence rise appreciably faster. In the observed general model the minimum space expansion speed is at Gyr. However, the distributions of the horizon expansion speed of the universe in the general models continuously reduce with cosmic time. At the present time in the observed general model . On the other hand, the distributions of the horizon volume speed of the universe expansion surge slowly until yr, afterwards they ascend more rapidly up to maximum values, and hence they decrease gradually towards zero. At the present time in the observed general model . While the maximum horizon volume speed is at Gyr. The distributions of the speed expansion acceleration of the universe in the general models exhibit steep rise towards and remain very close to this value, then they increase very slowly up to Gyr, then they rise more rapidly, however after Gyr they surge substantially faster. Nevertheless, the distributions of the horizon expansion acceleration of the universe in the general models display sharp ascension towards and stay so adjacent to this value hence after Gyr. Finally, the distributions of the horizon volume acceleration of the universe expansion in the general models reduce with time unit Gyr where they remain close to . At the present time in the observed general model . It is found that the four new cosmological quantities are strongly related to the distribution of the total pressure of the universe.
Bennett CL, et al. Astrophys. J. 2014;794:135.
Bukhari FA. Five general cosmic models. Journal of King Abdulaziz University, Science. 2013;25.
Kumar P, Singh CP. Astrophys Space Sci. 2017;362:52.
Brans C, Dicke H. Phys. Rev. 1961;124:925.
Bertotti B, Iess L, Tortora P. Nature. 2003;426: 374
Will C. Living Rev. Relativ. 2006;9:3.
Sultan J. MNRAS. 2016;457:212.
Capistrano AJS. MNRAS. 2015;448:1232.
Santos B, Coley AA. Chandrachani Devi, J. Alcaniz, S. J CAP02. 2017;047.
Bukhari FA. Cosmological distances in five general cosmic models, International Journal of Astronomy and Astroph.ysics. 2013;3:183-188.
Bukhari FA. Distribution of Mass and Energy in Five General Cosmic Models, International Journal of Astronomy and Astrophysics. 2015; 5:20-27.
Bukhari FA. Distribution of pressure in five general cosmic models, in preparation.