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Radiation properties of the accretion disk around a black hole in Einstein-Maxwell-scalar theory

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Chinese Physics C 2024年第2期48卷 162-170页

作者： Mirzabek Alloqulov Sanjar Shaymatov Bobomurat Ahmedov abdul jawad New Uzbekistan University Movarounnahr street 1Tashkent 100000Uzbekistan Institute of Fundamental and Applied Research National Research University TIIAMEKori Niyoziy 39Tashkent 100000Uzbekistan University of Tashkent for Applied Sciences Str.Gavhar 1Tashkent 100149Uzbekistan Institute for Theoretical Physics and Cosmology Zhejiang University of TechnologyHangzhou 310023China Central Asian University Milliy Bog Street 264Tashkent 111221Uzbekistan National University of Uzbekistan Tashkent 100174Uzbekistan Power Engineering Faculty Tashkent State Technical UniversityTashkent 100095Uzbekistan Ulugh Beg Astronomical Institute Astronomy St 33Tashkent 100052Uzbekistan Institute of Theoretical Physics National University of UzbekistanTashkent 100174Uzbekistan Department of Mathematics COMSATS University IslamabadLahore CampusLahore-54000Pakistan

In this study,we explore the properties of a non-rotating black hole in the Einstein-Maxwell-scalar(EMS)theory and investigate the luminosity of the accretion disk surrounding *** determine all the orbital parameters of particles in the accretion disk,including the radius of the innermost stable circular orbit(ISCO)with angular velocity,angular momentum,and ***,we study the radiative efficiency for different values of black hole ***,we analyze the flux,differential luminosity,and temperature of the accretion disk.

关键词： Einstein-Maxwell-scalar theory black hole accretion disk

Anisotropic Inflationary Scenario Via Generalized Chaplygin Gas Model

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Communications in Theoretical Physics 2016年第5期65卷 653-658页

作者： abdul jawad Shamaila Rani Department of Mathematics COMSATS Institute of Information Technology

We investigate generalized chaplygin gas for warm inflationary scenario in the context of locally rotationally symmetric Bianchi type I universe *** assume two different cases of dissipative coefficient,i.e.,constant as well as function of scalar *** construct dynamical equations as well as a relationship between scalar and radiation energy densities under slow-roll *** also derive slow-roll parameters,scalar and tensor power spectra,scalar spectral index,tensor to scalar ratio for analyzing inflationary background during high dissipative *** also use the WMAP7 data for the discussion of our parameters.

关键词： anisotropic universe model inflation generalized chaplygin gas

Accretion onto Charged Black Holes in Einstein and Massive Theories of Gravity

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Communications in Theoretical Physics 2019年第6期71卷 702-710页

作者： abdul jawad Shahid Chaudhary Department of Mathematics COMSATS UniversityIslamabadLahore Campus-54000Pakistan Department of Mathematics Sharif College of Engineering and TechnologyLahore-54000Pakistan

The accretion process is being investigated onto some important black holes such as Born-Infeld-AdS black hole, non-linear charged black hole solution in AdS space-time and Einstein-Yang-Mills massive gravity in the presence of Born-Infeld nonlinear electrodynamics. We find out the relations of radial velocity, energy density and change of mass for mention black holes and analyze their behavior graphically for different values of equation of state parameters ω.We also examine the relations for critical speed for these black holes. It is observed that for different state parameters different fluids exhibit different evolutions in black holes backgrounds. The energy density of some fluids is negative or positive near the black hole while other fluids become cause to increase or decrease in black hole mass.

关键词： accretion black holes Einstein gravity massive gravity

New Agegraphic Pilgrim Dark Energy in f(T, T_G) Gravity

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Communications in Theoretical Physics 2015年第8期64卷 145-150页

作者： abdul jawad Ujjal Debnath Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Indian Institute of Engineering Science and Technology

In this work, we briefly discuss a novel class of modified gravity like f(T, TG) gravity. In this background,we assume the new agegraphic version of pilgrim dark energy and reconstruct f(T, TG) models for two specific values of s. We also discuss the equation of state parameter, squared speed of sound and wDE-w DEplane for these reconstructed f(T, TG) models. The equation of state parameter provides phantom-like behavior of the universe. The wDE-w DEplane also corresponds to ΛCDM limit, thawing and freezing regions for both models.

关键词： f(T TG) gravity Pilgrim DE models cosmological par

Reconstruction of Scalar Field Dark Energy Models in Kaluza-Klein Universe

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Communications in Theoretical Physics 2013年第8期60卷 183-188页

作者： M.Sharif abdul jawad Department of Mathematics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

This paper is devoted to study the modified holographic dark energy model by taking its different aspects in the t/at Kaiuza-Klein universe. We construct the equation of state parameter which evolutes the universe from quintessence region towards the vacuum. It is found that the modified holographic model exhibits instability against small perturbations in the early epoch of the universe but becomes stable in the later times. We also develop its correspondence with some scalar field dark energy models. It is interesting to mention here that ail the results are consistent with the present observations.

关键词： Kaluza-Klein cosmology modified holographic dark energy scalar field models

Generalized Ghost Pilgrim Scalar Field Models of Dark Energy

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Communications in Theoretical Physics 2015年第11期64卷 590-596页

作者： abdul jawad Ujjal Debnath Fazal Batool Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Indian Institute of Engineering Science and Technology Department of Mathematics Lahore Leads University

We assume generalized ghost Pilgrim dark energy(GGPDE) model in the presence of cold dark matter in flat FRW *** suitable choice of interaction term between GGPDE and cold dark matter,we investigate the nature of equation of state parameter for ***,we investigate the natures of dynamical scalar field models(such as quintessence,tachyon,k-essence,and dilaton dark energy) and concerned potentials through the correspondence phenomenon between GGPDE and these models.

关键词： generalized ghost Pilgrim dark energy scalar field

Warm Standard Scalar Field Modified Chaplygin Gas Inflation Inspired by Generalized Dissipative Coefficient on the Brane

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Communications in Theoretical Physics 2017年第8期67卷 272-284页

作者： abdul jawad Faiza Gulshan Shamaila Rani Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Lahore Leads University

We discuss the warm inflation in the presence of standard scalar field model and modified Chaplyggin gas in brahe-world scenario. We consider weak and strong dissipative regimes with generalized dissipative coefficient. We extract various inflationary parameters. For example, we analyze the behavior of different ratios （ratio of dissipative co-efficient and Hubble parameter Г/3H, ratio of temperature and Hubble parameter T/ H, scalar-to-tensor ratio ＇r） with respect to spectral index ns for the weak and strong dissipative regimes through parametric plotting. It is found that T/H and Г/3H satisfied the required conditions in both dissipative regimes. It is also noted that the spectral index （ns） ns=0.96＋0.10-0.10 It is remarked here that our results are consistence with observational data WMAP7, WMAP9, and recent Planck data.

关键词： brane-world model standard scalar field model modified chaplygin gas inflationary parameters

Charged Noncommutative Wormhole Solutions via Power-Law f(T) Models

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Communications in Theoretical Physics 2016年第10期65卷 411-422页

作者： Shamaila Rani abdul jawad M.Bilal Amin Department of Mathematics COMSATS Institute of Information Technology

In this paper,we explore static spherically symmetric charged wormhole solutions in extended teleparallel gravity taking power-law f(T) *** consider noncommutative geometry under Lorentzian *** order to obtain matter components,we develop field equations using effective energy-momentum tensor for non-diagonal *** explore solutions by considering various viable power-law f(T) models,which also include teleparallel gravity *** violation of energy conditions obtain by exotic matter to form wormhole solutions in teleparallel case while,physical acceptable wormhole solutions exist for charged noncommutative wormhole solutions for some cases of power-law *** effective energy-momentum tensor and charge are responsible for the violation of the energy ***,we check the equilibrium condition for these *** equilibrium condition meets for the teleparallel case and some power-law solutions while remaining solutions are either in less equilibrium or in disequilibrium situation.

关键词： f(T) gravity wormhole Lorentzian distribution noncommutative geometry

Dynamics of Particles Around a Regular Black Hole with Nonlinear Electrodynamics

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Communications in Theoretical Physics 2016年第11期65卷 509-516页

作者： abdul jawad Farhad Ali Mubasher Jamil Ujjal Debnath Department of Mathematics COMSATS Institute of Information Technology Department of Mathematics Kohat University of Science and Technology Department of Mathematics School of Natural Sciences (SNS) National University of Sciences and Technology (NUST) Department of Mathematics Indian Institute of Engineering Science and Technology

We investigate the dynamics of a charged particle being kicked off from its circular orbit around a regular black hole by an incoming massive particle in the presence of magnetic field. The resulting escape velocity, escape energy and the effective potential are analyzed. It is shown that the presence of even a very weak magnetic field helps the charged particles in escaping the gravitational field of the black hole. Moreover the effective force acting on the particle visibly reduces with distance. Thus particle near the black hole will experience higher effective force as compared to when it is far away.

关键词： center of mass energy escape velocity electrodynamics regular black hole