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Browsing by Subject "Cosmology"

Browsing by Subject "Cosmology"

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  • Ensemble Average of Three-dimensional Minkowski Tensors of a Gaussian Random Field in Redshift Space 
    Appleby, S; Joby, P. K; Pravabati, C; Park, C (IOP Publishing, 2019-11-20)
    We present the ensemble expectation values for the translation-invariant, rank-2 Minkowski tensors in three dimensions, for a linearly redshift-space-distorted Gaussian random field. The Minkowski tensors W1 0,2, W2 0,2 ...
  • Ether, Luminosity and Galactic Source Counts 
    Tomaschitz, R (Kluwer Academic Publishers, 1998-08)
    An interpretation of the cosmological redshift in terms of a cosmic ether is given. We study a Robertson-Walker cosmology in which the ether is phenomenologically defined by a homogeneous and isotropic permeability tensor. ...
  • Evolution of metals and dust in the universe 
    Khare, P; Kulkarni, V. P; Lauroesch, L. T; Fall, S. M; York, D. G; Welty, D. E; Crotts, A. P. S; Truran, J. W; Nakamura, O (Astronomical Society of India, 2005-06)
    With the aim of determining the evolution of metals and dust in the universe, we have observed 8 Damped Lyman-alpha Absorbers (DLAs) with the Multiple Mirror Telescope and the Hubble Space Telescope at 0:1 < z < 1:5, ...
  • Extragalactic Radio Sources and Cosmology 
    Swarup, G (Astronomical Society of India, 1977-06)
  • A feasibility study of cosmic microwave radiation via graphite needles 
    Sivaram, C; Shah, G. A (D. Reidel Publishing Co.,, 1985-12)
    It is pointed out that the total amount of microwave radiation that could possibly be generated by all the graphite needles in space would be considerably smaller than the observed total energy of the cosmic microwave ...
  • Formation and Abundance of Late-forming Primordial Black Holes as Dark Matter 
    Chakraborty, Amlan; Chanda, Prolay K; Pandey, Kanhaiya L; Das, Subinoy (American Astronomical Society, 2022-06-20)
    We propose a novel mechanism where primordial black hole (PBH) dark matter is formed much later in the history of the universe, between the epochs of Big Bang nucleosynthesis and cosmic microwave background photon decoupling. ...
  • Fundamental interactions in the early universe 
    Sivaram, C (Springer, 1994-05)
    A unified approach to fundamental interactions as explored earlier is further elaborated and its consequences for the early universe studied especially in connection with the energy dependence of the coupling constants.
  • General upper limits to the age of the universe 
    Joshi, P. S (Astronomical Society of Indian, 1986-03)
    An inhomogeneous and anisotropic universe is modeled by means of a general class of relativistic space-times, and conclusions are derived concerning the most general upper bounds that can be set on the age of the universe. ...
  • The Hubble constant 
    Narlikar, J. V (Astronomical Society of India, 1996)
    In this talk the history of Hubble's constant is reviewed from the discovery of the velocity-distance relation to the present day measurements with the Hubble Space Telescope. The problems encountered in fixing the true ...
  • 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 ...
  • Large number coincidences and unification of the parameters underlying elementary particles astrophysics and cosmology 
    Sivaram, C (World Scientific, 1984)
    The Ubiquitous occurrence of the Dirac-Eddington large dimensionless numbers when relating the physical parameters such as mass, radius, angular momentum etc. of typical astrophys1cal objects like stars and galax1es to ...
  • Minkowski Tensors in Redshift Space—Beyond the Plane-parallel Approximation 
    Appleby, Stephen; Kochappan, Joby P; Pravabati, C; Park, Changbom (American Astronomical Society, 2023-01-10)
    The Minkowski tensors (MTs) can be used to probe anisotropic signals in a field, and are well suited for measuring the redshift-space distortion (RSD) signal in large-scale structure catalogs. We consider how the linear ...
  • Mond, dark matter and the cosmological constant 
    Sivaram, C (Springer, 1994-09)
    A possible connection between MOND (Modification of Newtonian Dynamics) proposed as an alternative hypothesis to dark matter in galaxies and clusters and a residual cosmological constant term dominating cosmological dynamics ...
  • Nobel Recognition of Cosmology 
    Narlikar, J. V (Astronomical Society of India, 1978-12)
  • A non-anthropic origin for a small cosmological constant 
    Sivaram, C (World Scientific Publishing, 1999-11)
    An impressive variety of recent observations which include luminosity evolutions of high redshift supernovae strongly suggest that the cosmological constant (Λ) is not zero. Even though the Λ-term may dominate cosmic ...
  • A non-anthropic origin for a small cosmological constant 
    Sivaram, C (Astronomical Society of India, 1999)
    An impressive variety of recent observations which include luminosity evolutions of high red shift supernovae strongly suggest that the cosmological constant (/\)is not zero. Even though the /\-term may dominate cosmic ...
  • Non-zero rest mass neutrinos and the cosmological constant 
    Sivaram, C (Kluwer Academic Publisher, 1985-11)
    Recently it was pointed out that a non-zero cosmological constant can play a role in the formation of neutrino halos only in the case of neutrinos of very low rest mass (mν ≤ 0.1 eV). However, phase-space considerations ...
  • Non-zero rest mass neutrinos and the cosmological constant 
    Sivaram, C (Kluwer Academic Publishers, 1985-11)
    Recently it was pointed out that a non-zero cosmological constant can play a role in the formation of neutrino halos only in the case of neutrinos of very low rest mass (mν ≤ 0.1 eV). However, phase-space considerations ...
  • Nonthermal warm dark matter limits from small-scale structure 
    Banerjee, Arka; Das, Subinoy; Maharana, Anshuman; Nadler, Ethan O.; Sharma, Ravi Kumar (American Physical Society, 2023-08-15)
    We present small-scale structure constraints on sterile dark matter produced from a heavy mediator particle, inspired by models of moduli decay. Dark matter particles produced through this mechanism can contribute to the ...
  • On structure formation in the universe 
    Satya Narayanan, A (Springer, 1994-12)
    The formation of structures in the universe is one of the most challenging problems of cosmology. In this paper, an attempt to explain the formation of galaxies through the generation of vortices (with dissipation) in an ...

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