Browsing by Author "Hadi, H."
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Item Open Access D-bound and Bekenstein bound for McVittie solution surrounded by dark energy cosmological fields(Springer, 2020-07) Hadi, H.; Darabi, F.; Atazadeh, K.; Heydarzade, YaghoubThe cosmological candidate fields for dark energy as quintessence, phantom and cosmological constant are studied in terms of an entropic hypothesis imposed on the McVittie solution surrounded by dark energy. We certify this hypothesis as “D-bound-Bekenstein bound identification” for dilute systems and use it as a criterion to determine which candidate of dark energy can satisfy this criterion for a dilute McVittie solution. It turns out that only the cosmological constant can pass this criterion successfully while the quintessence and phantom fields fail, as non-viable dark energy fields for this particular black hole solution. Moreover, assuming this black hole to possess the saturated entropy, the entropy-area law and the holographic principle can put two constraints on the radius R of the cosmological horizon. The first one shows that the Hubble radius is discrete such that for any arbitrary value of the black hole mass m0m0, the value of R is determined up to an integer number. The latter one shows that when a black hole is immersed in a cosmological background, the radius of the cosmological horizon is constrained as R<1HR<1H.Item Open Access D-bound and the Bekenstein bound for the surrounded Vaidya black hole(Springer Science and Business Media Deutschland GmbH, 2020-11) Hadi, H.; Darabi, F.; Atazadeh, K.; Heydarzade, YaghoubWe study the Vaidya black hole surrounded by the exotic quintessence-like, phantom-like and cosmological constant-like fields by means of entropic considerations. Explicitly, we show that for this thermodynamical system, the requirement of the identification of the D-bound and Bekenstein entropy bound can be considered as a thermodynamical criterion by which one can rule out the quintessence-like and phantom-like fields, and prefer the cosmological constant as a viable cosmological field.Item Open Access Entropic considerations on the Universe and Universe-black hole systems(IOP Publishing Ltd, 2020-08) Hadi, H.; Darabi, F.; Heydarzade, YaghoubWe study the entropic considerations on the Universe system and the Universe-black hole system, filled by cosmological constant or exotic quintessence-like and phantom-like fields having negative pressure, using their relevant entropic bounds. It turns out that for both systems these considerations single out the cosmological constant, among the negative pressure candidate fields, as the viable cosmological field.