Gravitational Collapse and Singularities in Some Non-Schwarzschild's Space-Times
Chifu Ebenezer Ndikilar,
Abu Ovansa Samson,
Hafeez Yusuf Hafeez
Issue:
Volume 6, Issue 6, December 2018
Pages:
93-100
Received:
6 November 2018
Accepted:
19 November 2018
Published:
7 January 2019
DOI:
10.11648/j.ijass.20180606.11
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Abstract: Singularities in three non-Schwarzschild space-times: Minkowski, Friedman-Lemaitre-Robertson-Walker and Reissner-Nordstromare investigated. Gravitational collapse in the Schwarzschild solution is obvious and widely studied. However, gravitational collapse should not be limited to Schwarzschild solution only as interesting findings exist in other metric fields. The Ricci curvature scalar for each space-time is evaluated and used in the determination of true curvature singularities. The Ricci scalar has proved to be very effective in determining the presence of singularities or otherwise in space-time geometry. Results indicate that there are inherent singularities in components of space-time in all three cases. Gravitational singularities in Minkowski space are found to be consequences of the choice of coordinate. Minkowksi space possesses only coordinate singularities and no curvature singularity. This differs with Schwarzschild’s metric which has true curvature singularity. Friedman-Lemaitre-Robertson-Walker (FLRW) and Reissner-Nordstrom metrics have true curvature singularities. Gravitational collapse in the FLRW metric yields a curvature singularity which shows the universe started a finite time ago. Cosmic strings, white holes and blackholes are deduced from the Reissner-Nordstrom singularities. Reissner-Nordstrom solution show that the addition of small amounts of electric charge or angular momentum could completely alter the nature of the singularity, causing the matter to fall through a ‘wormhole’ and emerge into another universe. Analysis of gravitational collapse in this article provides one of the most exciting research frontiers in gravitation physics and high energy astrophysics; as the debate on their physical existence persists.
Abstract: Singularities in three non-Schwarzschild space-times: Minkowski, Friedman-Lemaitre-Robertson-Walker and Reissner-Nordstromare investigated. Gravitational collapse in the Schwarzschild solution is obvious and widely studied. However, gravitational collapse should not be limited to Schwarzschild solution only as interesting findings exist in other me...
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On the Effects of Spin Properties on Timing Noise Parameters of Rotation-Powered Pulsars
Evaristus Uzochukwu Iyida,
Christian Ikechukwu Eze,
Innocent Okwudili Eya,
Augustine Ejikeme Chukwude
Issue:
Volume 6, Issue 6, December 2018
Pages:
101-107
Received:
3 November 2018
Accepted:
22 November 2018
Published:
13 January 2019
DOI:
10.11648/j.ijass.20180606.12
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Abstract: Detailed investigation of improved timing observations has shown that the spin properties of a large population of rotation-powered pulsars on a varied range of timescales are strongly dominated by random fluctuations. Even though, there is no widely accepted way to characterize timing noise in these pulsars mainly due to the enormous complexity in their structure and true dynamical behavior, the measurements of these pulsar spin properties are essential for extracting important information about their spin down evolution. In this paper, a statistical analysis of a large sample of Jodrell Bank Observatory (JBO) radio pulsars with improved and published data on stability parameters (∆8) and other quantities that are used to parameterize pulsar rotational fluctuations on observation timescales [timing noise activity parameter A, timing noise statistic (σ23) and pulsar clock stability parameter σZ (T)] was compiled for an in-depth characterization of the spin-down evolution of rotation-powered pulsars. The existence of any relationship will go a long way in helping us probe the properties and dynamics of a neutron star. The results of our analysis reveal that radio pulsar spin-down parameters are reasonably coupled to timing noise activity. A simple regression analysis of our data show that timing irregularities in pulsar is more than 75% correlated with the magnitude of pulsar spin-down variables. The implications of the result of the improved measurements of the key parameters characterizing the spin-down of pulsars on long timescales are discussed.
Abstract: Detailed investigation of improved timing observations has shown that the spin properties of a large population of rotation-powered pulsars on a varied range of timescales are strongly dominated by random fluctuations. Even though, there is no widely accepted way to characterize timing noise in these pulsars mainly due to the enormous complexity in ...
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