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FIZIKA B 16 (2007) 3, 141 - 158
 
NONSINGULAR COSMOLOGICAL MODELS WITH A VARIABLE COSMOLOGICAL TERM
L
ANIRUDH PRADHAN a,c KASHIKA SRIVASTAVAa,d and AMRIT LAL AHUJAb
aDepartment of Mathematics, Hindu Post-graduate College, Zamania-232 331, Ghazipur, India
bInter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune-411 007, India
E-addresses:
cpradhan@iucaa.ernet.in;
bahuja@iucaa.ernet.in;
dkash_gg@yahoo.co.uk
Received 9 March 2007; Revised manuscript received 23 June 2007
Accepted 22 October 2007 Online 15 February 2008
Exact solutions of the Einstein's field equations describing a spherically
symmetric cosmological model without a big bang or any other kind of singularity
recently obtained by Dadhich and Patel (2000) are revisited. The matter content
of the model is a shear-free perfect fluid with isotropic pressure and a radial
heat flux. Three different exact solutions are obtained both for perfect fluid
and fluid with bulk viscosity. It turns out that the cosmological term
L(t) is a decreasing function of time, which is consistent with recent
observations of type Ia supernovae.
PACS numbers: 98.80.Es, 98.80.-k
UDC 524.83
Keywords: non-singular models, cosmology, variable cosmological constant,
causality principle
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