arXiv subjects

Naba Jyoti Gogoi

Publications and source records attributed to Naba Jyoti Gogoi.

6 recordsLinked to original sources

arXiv2026

Extended Thermodynamics and Throttling Process of Charged AdS Black Holes in ModMax-dRGT Massive Gravity with Sharma-Mittal Entropy

We investigate the extended thermodynamics, including the Joule-Thomson expansion and $P-V$ criticality, of a four-dimensional charged anti-de Sitter (AdS) black hole within the combined framework of ModMax nonlinear electrodynamics and dRGT-like massive gravity. Operating in the extended phase space and employing the generalised Sharma-Mittal entropy to account for non-extensive statistical correlations, we derive exact analytical expressions for the modified Hawking temperature, specific heat, Joule-Thomson coefficient, and the equation of state. Our analysis of the throttling process reveals that the conformal nonlinearities of the ModMax field ($γ$) expand the physically accessible cooling domain by shifting the inversion transition to smaller horizon radii. While the Sharma-Mittal parameters ($δ$, $R$) critically govern local thermodynamic stability and the inversion radius, the global inversion phase boundary remains fundamentally dictated by the massive graviton background. Furthermore, an analysis of the Gibbs free energy uncovers a van der Waals-like first-order phase transition characterized by a distinct swallow-tail structure. We observe a clear physical decoupling in the critical regime: ModMax nonlinearities modify the critical phase boundary by suppressing electromagnetic interactions, Sharma-Mittal parameters dictate the relative thermal stability of competing phases, and massive gravity governs the overarching macroscopic phase landscape. These results highlight the sensitivity of thermodynamic phase phenomena as robust diagnostic tools for distinguishing nonlinear and non-extensive modifications to black hole physics.

gr-qc↗

arXiv2025

Revisiting thermodynamic topology of Hawking-Page and Davies type phase transitions

In this work, we propose a common vector field to study the thermodynamic topology of the Davies type and Hawking-Page phase transitions. Existing literature has shown that studying these two types of phase transitions typically requires defining two separate vector fields . In our approach, we adopt Duan's $ϕ$-mapping topological current theory to define a novel vector field, denoted as $ϕ$, whose critical points exactly correspond to the Davies point and the Hawking-Page phase transition point. More importantly, we can differentiate between these two points by their topological charge. While, the topological charge for the critical point corresponding to the Davies-type phase transition is found to be $-1$, the same for the Hawking-Page phase transition point, it is $+1$. Although our analysis is applicable to all black hole systems where both types of phase transitions are found, we illustrate it using three simple systems as examples: the Schwarzschild AdS black hole, the Reissner-Nordström AdS black hole in the grand canonical ensemble, and finally the Kerr AdS black holes in the grand canonical ensemble. It is wellknown that these black holes exhibit both Davies and Hawking-Page phase transitions. With our proposed vector $ϕ$, the critical points obtained for these three systems exactly match the Davies-type and Hawking-Page phase transition points, and the associated topological charges are found to be $-1$ for the Davies point and $+1$ for the Hawking-Page phase transition point.

hep-th↗

arXiv2024

Lyapunov Exponents and Phase Transition of Hayward AdS Black Hole

In this paper, we study the relationship between the phase transition and Lyapunov exponents for 4D Hayward anti-de Sitter (AdS) black hole. We consider the motion of massless and massive particles around an unstable circular orbit of the Hayward AdS black hole in the equatorial plane and calculate the corresponding Lyapunov exponents. The phase transition is found to be well described by the multivaled Lyapunov exponents. It is also found that different phases of Hayward AdS black hole coincide with different branches of the Lyapunov exponents. We also study the discontinuous change in the Lyapunov exponents and find that it can serve as an order parameter near the critical point. The critical exponent of change in Lyapunov exponent near the critical point is found to be $1/2$.

hep-th↗

arXiv2023

Thermodynamic topology of 4D Euler-Heisenberg-AdS black hole in different ensembles

We study the thermodynamic topology of 4D Euler-Heisenberg-AdS (EHAdS) black hole and higher-order QED corrected Euler-Heisenberg-AdS black hole in different ensembles using generalized off-shell free energy. In this approach, black holes are viewed as defects in the thermodynamic space. We work in two ensembles: canonical ensemble in which the charge is kept fixed and grand canonical ensemble in which the conjugate potential $ϕ_e$ is kept fixed. In each case, the local and global topology of the thermodynamic space is investigated via the computation of winding numbers at the defects. For 4D Euler-Heisenberg-AdS black hole in canonical ensemble, the topological class is found to be different depending on the Euler-Heisenberg (EH) parameter $a$. The topological numbers for $a<0$ and $a>0$ cases are found to be $W=+1$ and $W=0$ respectively. The topological number is found to be independent of the variation in pressure $P$ and charge $Q$ of the black hole. With the introduction of higher order QED correction, the difference in the topological class of 4D EHAdS black hole with the sign of $a$ is observed to go away.The topological number in this case is found to be $W=+1$ irrespective of the values of $a$, $P$ and $Q$. In the grand canonical ensemble, the topological number for both EHAdS and higher order QED corrected EHAdS black hole is found to be $W=0$, independent of the values of $P$, $ϕ_e$ and $a$. Therefore, we infer that the topological class of both 4D EHAdS black hole and higher order QED corrected EHAdS black hole is ensemble dependent. Moreover, in the canonical ensemble, higher order QED correction alters the topological class of the black hole for positive values of EH parameter $a$. In the grand canonical ensemble, the higher order corrections do not change the thermodynamic topology of the black hole.

hep-th↗

arXiv2023

Joule-Thomson expansion and Optical behaviour of Reissner-Nordström-Anti-de Sitter black holes in Rastall gravity surrounded by a Quintessence field

This paper deals with the thermodynamics, Joule-Thomson expansion and optical behaviour of a Reissner-Nordström-anti-de Sitter black hole in Rastall gravity surrounded by a quintessence field. The black hole solution obtained in this framework is different from a corresponding black hole in General Relativity. The black hole metric function, as well as the Hawking temperature, is affected by the presence of energy-momentum conservation violation. The presence of energy-momentum conservation violation also affects the isenthalpic and inversion temperature curves, and with an increase in the Rastall parameter, the inversion temperature rises slowly. The impacts of other parameters, such as charge, structural constant etc., are investigated and compared. The black hole shadow, as well as the energy emission rate of the black hole, decreases with an increase in the Rastall parameter. Hence, the black holes evaporate slowly in presence of energy-momentum conservation violation.

gr-qc↗

arXiv2023

Thermodynamic topology of 4D Dyonic AdS black holes in different ensembles

We study the thermodynamic topology of four dimensional dyonic Anti-de-Sitter(AdS) black hole in three different ensembles: canonical, mixed and grand canonical ensemble. While canonical ensemble refers to the ensemble with fixed electric and magnetic charges, mixed ensemble is an ensemble where we fix magnetic charge and electric potential. In the grand canonical ensemble, potentials corresponding to both electric and magnetic charges are kept fixed. In each of these ensembles, we first compute the topological charges associated with critical points. We find that while in both canonical and mixed ensembles, there exists one conventional critical point with topological charge $-1$, in the grand canonical ensemble, we find no critical point. Then, we consider the dyonic AdS black hole as topological defects in thermodynamic space and study its local and global topology by computing the winding numbers at the defects. We observe that while the topologies of the black hole in canonical and mixed ensembles are identical with total topological charge equaling $1$, in the grand canonical ensemble, depending on the values of potentials, the total topological charge is either equal to $0$ or $1$. In canonical and mixed ensembles, either one generation and one annihilation points or no generation/annihilation points are found. In the grand canonical ensemble, depending on the values of potentials, we find either one generation point or no generation/annihilation point. Thus, we infer that the topological class of $4$D dyonic AdS black hole is ensemble dependent.

hep-th↗