A. Qadir - Academia.edu (original) (raw)
Papers by A. Qadir
Pramana, Oct 2, 2015
The set of three static spherically symmetric solutions of the Einstein–Maxwell field equations b... more The set of three static spherically symmetric solutions of the Einstein–Maxwell field equations by Maurya and Gupta, Astrophys. Space Sci.333, 149 (2011) are modified by introducing the variable cosmological term. Motivated by Tiwari et al, Indian J. Pure Appl. Math.31, 1017 (2000), some particular values of the cosmological term are taken to obtain well-behaved solutions of the Einstein–Maxwell field equations. All the results given by Maurya and Gupta can be obtained as particular cases of our solutions by choosing a cosmological term equal to zero.
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Physical Review D
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Lettere al Nuovo Cimento, 1980
An alternative model for identifying pulsars with rotating neutron stars is proposed in order to ... more An alternative model for identifying pulsars with rotating neutron stars is proposed in order to explain the observed pulsar emission figures. Equations of a dimensionless quantity, independent of the neutron star parameters, are obtained with respect to the deceleration rate. It is noted that this rate is directly related to the energy generation processes of pulsars.
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SPIE Proceedings, 2013
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Noraiz Tahir, Asghar Qadir, Muhammad Sakhi, and Francesco De Paolis Department of Mathematics and... more Noraiz Tahir, Asghar Qadir, Muhammad Sakhi, and Francesco De Paolis Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via per Arnesano, I-73100 Lecce, Italy INFN, Sezione di Lecce, Via per Arnesano, I-73100 Lecce, Italy Abdus Salam School of Mathematics, G.C. University, Lahore, Pakistan Department of Physics, Quaid-e-Azam University, Islamabad, Pakistan noraiz.tahir@le.infn.it asgharqadir46@gmail.com sakhi.cosmos@gmail.com †††† francesco.depaolis@le.infn.it
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Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polari... more Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polarization, offer a unique view of the universe properties and of the formation and evolution of its structures. The last release, close to be finalized, of the Planck mission results sets the scene for cosmological models and parameters, while the comparison with other types of data sets raises the issue of possible tensions about some parameters, first of all the Hubble constant. At the same time, on the extragalactic side, Planck carried out the deepest systematic all-sky survey of SZ galaxy clusters and detected thousands of dusty galaxies and many hundreds of extragalactic radio sources, also allowing us to investigate many specific topics, including molecular hydrogen clouds in galactic halos. The exploitation of future generation of CMB missions and the next radio facilities will allow us to deeply investigate several topics in cosmology and astrophysics, from the existence of primord...
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The European Physical Journal C
The analysis of WMAP and Planck CMB data has shown the presence of temperature asymmetries toward... more The analysis of WMAP and Planck CMB data has shown the presence of temperature asymmetries towards the halos of several galaxies, which is probably due to the rotation of clouds present in these halos about the rotational axis of the galaxies. It had been proposed that these are hydrogen clouds that should be in equilibrium with the CMB. However, standard theory did not allow equilibrium of such clouds at the very low CMB temperature, but it was recently shown that the equilibrium could be stable. This still does not prove that the cloud concentration and that the observed temperature asymmetry is due to clouds in equilibrium with the CMB. To investigate the matter further, it would be necessary to trace the evolution of such clouds, which we call “virial clouds”, from their formation epoch to the present, so as to confront the model with the observational data. The task is to be done in two steps: (1) from the cloud formation before the formation of first generation of stars; (2) f...
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arXiv: Astrophysics, 1995
Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and m... more Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and may lead to the birth of massive halo objects (MHOs) observed indirectly by microlensing. We present a method to detect these molecular clouds in the halo of M31 using the Doppler shift effect. We also consider the possibility to directly observe MHOs in the halo of M31 via their infrared emission.
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Arxiv preprint astro-ph/ …, 1995
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This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck o... more This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-South and East-West temperature asymmetry is found, extending up to galactocentric distances of about 1.5. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the CMB temperature asymmetry method thus is shown to act as a direct tool to map the galactic haloes and/or the intergalactic bridges, invisible in other bands or by other methods.
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Using geometric methods for linearizing systems of second order cubically semi-linear ordinary di... more Using geometric methods for linearizing systems of second order cubically semi-linear ordinary differential equations and third order quintically semi-linear ordinary differential equations, we extend to the fourth order by differentiating the third order equation. This yields criteria for linearizability of a class of fourth order semi-linear ordinary differential equations, which have not been discussed in the literature previously. It is shown that the procedure can be extended to higher order. Though the results for the higher orders are complicated, they are doable by algebraic computing. The standard Lie approach, as developed at present does not seem to be amenable to giving results that can be handled even by algebraic computing.
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Astronomy and Astrophysics
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Astronomy & Astrophysics, 2015
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Journal of Nonlinear Mathematical Physics, 2008
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Journal of Mathematical Physics, 1987
ABSTRACT
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Journal of mathematical physics, 1993
... conservation laws that may be admitted in the standard form of general relativity.&am... more ... conservation laws that may be admitted in the standard form of general relativity.&amp;amp;#x27; Some more rigorous work was done on the important role of Ricci collineations admitted by certain relativistic matter fields and the related conservation laws that may ... c3= -csc aA,+cot 8A2+A3(t,r,4 ...
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Physical Review D, 2001
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gravityresearchfoundation.org
Perlurbative Invariance: A Proposal for a New Physical Principle Asghar Qadir* Department of Math... more Perlurbative Invariance: A Proposal for a New Physical Principle Asghar Qadir* Department of Mathematics, Quaid-i-Azam University, Islamabad, Pakistan and Department of Mathematical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 3126], Saudi Arabia ...
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Lettere Al Nuovo Cimento (19711985), 1974
... K. AHMED Department o] Physics, University o/ Islamabad - Islamabad ... Following BELLINI and... more ... K. AHMED Department o] Physics, University o/ Islamabad - Islamabad ... Following BELLINI and GIA~BIAGI (~) (hereafter referred to as BG), we have re-exaznined the problem of infra-red divergence in v-dimensional quantum electro-dynamics. ...
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Pramana, Oct 2, 2015
The set of three static spherically symmetric solutions of the Einstein–Maxwell field equations b... more The set of three static spherically symmetric solutions of the Einstein–Maxwell field equations by Maurya and Gupta, Astrophys. Space Sci.333, 149 (2011) are modified by introducing the variable cosmological term. Motivated by Tiwari et al, Indian J. Pure Appl. Math.31, 1017 (2000), some particular values of the cosmological term are taken to obtain well-behaved solutions of the Einstein–Maxwell field equations. All the results given by Maurya and Gupta can be obtained as particular cases of our solutions by choosing a cosmological term equal to zero.
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Physical Review D
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Lettere al Nuovo Cimento, 1980
An alternative model for identifying pulsars with rotating neutron stars is proposed in order to ... more An alternative model for identifying pulsars with rotating neutron stars is proposed in order to explain the observed pulsar emission figures. Equations of a dimensionless quantity, independent of the neutron star parameters, are obtained with respect to the deceleration rate. It is noted that this rate is directly related to the energy generation processes of pulsars.
Bookmarks Related papers MentionsView impact
SPIE Proceedings, 2013
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Noraiz Tahir, Asghar Qadir, Muhammad Sakhi, and Francesco De Paolis Department of Mathematics and... more Noraiz Tahir, Asghar Qadir, Muhammad Sakhi, and Francesco De Paolis Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via per Arnesano, I-73100 Lecce, Italy INFN, Sezione di Lecce, Via per Arnesano, I-73100 Lecce, Italy Abdus Salam School of Mathematics, G.C. University, Lahore, Pakistan Department of Physics, Quaid-e-Azam University, Islamabad, Pakistan noraiz.tahir@le.infn.it asgharqadir46@gmail.com sakhi.cosmos@gmail.com †††† francesco.depaolis@le.infn.it
Bookmarks Related papers MentionsView impact
Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polari... more Cosmological and astrophysical surveys from radio to far-infrared, in both temperature and polarization, offer a unique view of the universe properties and of the formation and evolution of its structures. The last release, close to be finalized, of the Planck mission results sets the scene for cosmological models and parameters, while the comparison with other types of data sets raises the issue of possible tensions about some parameters, first of all the Hubble constant. At the same time, on the extragalactic side, Planck carried out the deepest systematic all-sky survey of SZ galaxy clusters and detected thousands of dusty galaxies and many hundreds of extragalactic radio sources, also allowing us to investigate many specific topics, including molecular hydrogen clouds in galactic halos. The exploitation of future generation of CMB missions and the next radio facilities will allow us to deeply investigate several topics in cosmology and astrophysics, from the existence of primord...
Bookmarks Related papers MentionsView impact
The European Physical Journal C
The analysis of WMAP and Planck CMB data has shown the presence of temperature asymmetries toward... more The analysis of WMAP and Planck CMB data has shown the presence of temperature asymmetries towards the halos of several galaxies, which is probably due to the rotation of clouds present in these halos about the rotational axis of the galaxies. It had been proposed that these are hydrogen clouds that should be in equilibrium with the CMB. However, standard theory did not allow equilibrium of such clouds at the very low CMB temperature, but it was recently shown that the equilibrium could be stable. This still does not prove that the cloud concentration and that the observed temperature asymmetry is due to clouds in equilibrium with the CMB. To investigate the matter further, it would be necessary to trace the evolution of such clouds, which we call “virial clouds”, from their formation epoch to the present, so as to confront the model with the observational data. The task is to be done in two steps: (1) from the cloud formation before the formation of first generation of stars; (2) f...
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arXiv: Astrophysics, 1995
Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and m... more Molecular hydrogen clouds can contribute substantially to the galactic halo< dark matter and may lead to the birth of massive halo objects (MHOs) observed indirectly by microlensing. We present a method to detect these molecular clouds in the halo of M31 using the Doppler shift effect. We also consider the possibility to directly observe MHOs in the halo of M31 via their infrared emission.
Bookmarks Related papers MentionsView impact
Arxiv preprint astro-ph/ …, 1995
Bookmarks Related papers MentionsView impact
This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck o... more This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-South and East-West temperature asymmetry is found, extending up to galactocentric distances of about 1.5. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the CMB temperature asymmetry method thus is shown to act as a direct tool to map the galactic haloes and/or the intergalactic bridges, invisible in other bands or by other methods.
Bookmarks Related papers MentionsView impact
Using geometric methods for linearizing systems of second order cubically semi-linear ordinary di... more Using geometric methods for linearizing systems of second order cubically semi-linear ordinary differential equations and third order quintically semi-linear ordinary differential equations, we extend to the fourth order by differentiating the third order equation. This yields criteria for linearizability of a class of fourth order semi-linear ordinary differential equations, which have not been discussed in the literature previously. It is shown that the procedure can be extended to higher order. Though the results for the higher orders are complicated, they are doable by algebraic computing. The standard Lie approach, as developed at present does not seem to be amenable to giving results that can be handled even by algebraic computing.
Bookmarks Related papers MentionsView impact
Astronomy and Astrophysics
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Astronomy & Astrophysics, 2015
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Nonlinear Mathematical Physics, 2008
Bookmarks Related papers MentionsView impact
Journal of Mathematical Physics, 1987
ABSTRACT
Bookmarks Related papers MentionsView impact
Journal of mathematical physics, 1993
... conservation laws that may be admitted in the standard form of general relativity.&am... more ... conservation laws that may be admitted in the standard form of general relativity.&amp;amp;#x27; Some more rigorous work was done on the important role of Ricci collineations admitted by certain relativistic matter fields and the related conservation laws that may ... c3= -csc aA,+cot 8A2+A3(t,r,4 ...
Bookmarks Related papers MentionsView impact
Physical Review D, 2001
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gravityresearchfoundation.org
Perlurbative Invariance: A Proposal for a New Physical Principle Asghar Qadir* Department of Math... more Perlurbative Invariance: A Proposal for a New Physical Principle Asghar Qadir* Department of Mathematics, Quaid-i-Azam University, Islamabad, Pakistan and Department of Mathematical Sciences, King Fahd University of Petroleum and Minerals, Dhahran 3126], Saudi Arabia ...
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Lettere Al Nuovo Cimento (19711985), 1974
... K. AHMED Department o] Physics, University o/ Islamabad - Islamabad ... Following BELLINI and... more ... K. AHMED Department o] Physics, University o/ Islamabad - Islamabad ... Following BELLINI and GIA~BIAGI (~) (hereafter referred to as BG), we have re-exaznined the problem of infra-red divergence in v-dimensional quantum electro-dynamics. ...
Bookmarks Related papers MentionsView impact