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Browsing by Author "Arun, K"

Browsing by Author "Arun, K"

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  • Alternate Models to Dark Energy 
    Arun, K; Gudennavar, S. B; Prasad, A; Sivaram, C (Elsevier B.V, 2018-01)
    One of the unresolved questions currently in cosmology is that of the non-linear accelerated expansion of the universe. This has been attributed to the so called Dark Energy (DE). The accelerated expansion of the universe ...
  • A critique on Drexler dark matter 
    Sivaram, C; Arun, K; Nagaraja, R (Springer, 2011-05)
    Drexler dark matter is an alternate approach to dark matter that assumes that highly relativistic protons trapped in the halo of the galaxies could account for the missing mass. We look at various energetics involved in ...
  • Curvature, phase space, holography and black hole entropy 
    Sivaram, C; Arun, K (World Scientific Publishing, 2009-12)
    This paper discusses the thermodynamics of a black hole with respect to Hawking radiation and the entropy. We look at a unified picture of black hole entropy and curvature and how this can lead to the usual black hole ...
  • Dark energy constraints on masses and sizes of large scale cosmic structures 
    Rebecca, L; Arun, K; Sivaram, C (Springer, 2018-07)
    The requirement that their gravitational binding self-energy density must at least equal the background repulsive dark energy density for large scale cosmic structures implies a mass-radius relation of M/R2 ≈ 1 g/cm2, as ...
  • Dark matter density distributions and dark energy constraints on structure formation including MOND 
    Rebecca, L; Arun, K; Sivaram, C (Springer, 2020-09)
    In recent papers, it was shown explicitly that the sizes of gravitationally bound large-scale cosmic structures can be constrained from the requirement that their gravitational binding self-energy density should at least ...
  • Dark Matter Objects: Possible New Source of Gravitational Waves 
    Sivaram, C; Arun, K (Springer, 2019-10)
    Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier ...
  • Dieterici gas as a unified model for dark matter and dark energy 
    Sivaram, C; Arun, K; Nagaraja, R (Springer, 2011-10)
    The dominance of dark energy in the universe has necessitated the introduction of a repulsive gravity source to make q0 negative. The models for dark energy range from a simple term to quintessence, Chaplygin gas, ...
  • Effects of dark matter in star formation 
    Arun, K; Gudennavar, S; Prasad, A; Sivaram, C (Springer, 2019-02)
    The standard model for the formation of structure assumes that there existed small fluctuations in the early universe that grew due to gravitational instability. The origins of these fluctuations are as yet unclear. In ...
  • Enigmatic aspects of entropy inside the black hole: what do falling comoving observers see? 
    Sivaram, C; Arun, K (Springer, 2012-01)
    In a recent paper it was suggested that inclusion of mutual gravitational interactions can give a possible scenario for reversing gravitation collapse and averting a singular phase. We extend this idea to the still unsolved ...
  • Enigmatic aspects of the early universe: possibility of a `pre-big bang phase'! 
    Sivaram, C; Arun, K (Springer, 2011-05)
    In this paper it is suggested that inclusion of mutual gravitational interactions among the particles in the early dense universe can lead to a ‘pre-big bang’ scenario, with particle masses greater than the Planck mass ...
  • Evolution of primordial dark matter planets in the early Universe 
    Kiren, O. V; Arun, K; Sivarani, C (Elsevier B. V, 2021-08-15)
    In a recent paper we had discussed possibility of DM at high redshifts forming primordial planets composed entirely of DM to be oneof the reasons for not detecting DM (as the flux of ambient DM particles would be consequently ...
  • Evolution of time concept in physics and in philosophy 
    Sivaram, C; Arun, K; Kiren, O. V (Science Publications, 2015-07)
    What is ‘time’? This is a question that has perplexed many aphysicist and philosophers alike. The perception of the passage of timeappears ingrained in all biological systems where growth, evolution anddecay of objects, ...
  • Extended Equivalence Principle: Implications for Gravity, Geometry and Thermodynamics 
    Sivaram, C; Arun, K (Handronic Press Inc, 2012)
    The equivalence principle was formulated by Einstein in an attempt to extend the concept of inertial frames to accelerated frames. Thereby bringing in gravity. In recent decades, it has been realized that gravity is linked ...
  • Extremal charged black holes, dark matter and dark energy 
    Sivaram, C; Arun, K; Prasad, A (Springer, 2018-10)
    Formation of black holes may be constrained by intrinsic parameters characterizing them such as electric charge. Here we discuss the effects of a relatively minute excess of charge on extremal black hole formation and the ...
  • Forming supermassive black holes like J1342+0928 (invoking dark matter) in early universe 
    Sivaram, C; Arun, K; Kiren, O. V (Springer, 2018-02)
    Recent discovery of J1342+0928 using data from the WISE telescope and ground based surveys indicate presence of a supermassive black hole (SMBH) having a mass of 800 million solar mass at a redshift of about 7.6. This imply ...
  • Gravity of accelerations on quantum scales and its consequences 
    Sivaram, C; Arun, K; Kiren, O. V; Sreenath, B. N (Hadronic Press Inc, 2015-12)
    Gravity stands apart from other fundamental interactions in that it is locally equivalent to an accelerated frame and can be transformed away. Again it is indistinguishable from the geometry of space-time (which is an arena ...
  • Holography, dark energy and entropy of large cosmic structures 
    Sivaram, C; Arun, K (Springer, 2013-11)
    As is well known, black hole entropy is proportional to the area of the horizon suggesting a holographic principle wherein all degrees of freedom contributing to the entropy reside on the surface. In this note, we point ...
  • The Hubble tension: change in dark energy or a case for modified gravity? 
    Sivaram, C; Arun, K; Rebecca, Louise (Springer, 2022-03)
    Recently, much controversy has been raised about the cosmological conundrum involving the discrepancy in the value of the Hubble constant as implied by Planck satellite observations of the CMBR in the early Universe and ...
  • Hundred Years of Einstein's Cosmological Constant 
    Sivaram, C; Arun, K; Kiren, O. V; Sivaram, C (Isaac Scientific Publishing, 2018-06)
    It was little over a hundred years ago that Einstein introduced the ‘cosmological constant’ in his General Theory of Relativity in order to obtain a static universe, to conform to the philosophical view of the universe ...
  • Implications of Possible Alternate Scenarios for Short and Long Duration GRBs 
    Sivaram, C; Arun, K; Kiren, O. V (Bentham Open, 2014-12)
    Gamma-ray bursts (GRB) are the most luminous physical phenomena in the universe, consisting of flashes of gamma rays that last from seconds to hours. In this paper we look at possible alternate scenarios for both short and ...

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