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pro vyhledávání: '"Gupta, Rajendra P."'
Autor:
Gupta, Rajendra
Publikováno v:
MNRAS 524, 3385-3395 (2023)
Deep space observations of the James Webb Space Telescope (JWST) have revealed that the structure and masses of very early Universe galaxies at high redshifts (z~15), existing at ~0.3 Gyr after the BigBang, maybe as evolved as the galaxies in existen
Externí odkaz:
http://arxiv.org/abs/2309.13100
Autor:
Gupta, Rajendra P.
Publikováno v:
Universe 2023, 9(2), 70
Equations governing the evolution of a star involve multiple coupling constants. Thus, the time it spends as a main-sequence star can be expected to depend on whether or not such constants vary over the time scale of stellar evolution. When the star
Externí odkaz:
http://arxiv.org/abs/2302.00552
Autor:
Gupta, Rajendra P.
Publikováno v:
Symmetry 15, 259 (2023)
Dirac, in 1937 proposed the variation of coupling constants derived from his large number hypothesis. Efforts have continued since then to constrain their variation by various methods. We briefly discuss several methods used for the purpose while foc
Externí odkaz:
http://arxiv.org/abs/2301.09795
Autor:
Gupta, Rajendra P.
A Kibble balance measures the $gravitational$ mass (weight) of a test mass with extreme precision by balancing the gravitational pull on the test mass against the electromagnetic lift force. The uncertainty in such mass measurement is currently ~$1\t
Externí odkaz:
http://arxiv.org/abs/2207.02680
Publikováno v:
Symmetry 15, 709 (2023)
A scalar-tensor theory of gravity is considered wherein the gravitational coupling $G$ and the speed of light $c$ are admitted as space-time functions and combine to form the definition of the scalar field $\phi$. The varying $c$ participates in the
Externí odkaz:
http://arxiv.org/abs/2204.00119
Autor:
Gupta, Rajendra P.
The 'extreme Population A (xA) quasars' approaching, sometimes exceeding the Eddington limit, are a type of quasars that could serve as a standard candle to measure distances too large for supernovae type Ia (SNe Ia) to be observable. For using xA qu
Externí odkaz:
http://arxiv.org/abs/2202.12758
Autor:
Gupta, Rajendra P
Publikováno v:
Modern Physics Letters A 37, 2250155 (2022)
Since Dirac predicted in 1937 possible variation of gravitational constant and other coupling constants from his large number hypothesis, efforts continue to determine such variation without success. Such efforts focus on the variation of one constan
Externí odkaz:
http://arxiv.org/abs/2201.11667
Autor:
Gupta, Rajendra P.
Type 1a supernovae, SNeIa, are used as standard candles in cosmology for determining the distances of the galaxies harboring them. We show that the luminosity of an SNIa depends on its distance from us when physical constants (the speed of light $c$,
Externí odkaz:
http://arxiv.org/abs/2112.10654
Autor:
Gupta, Rajendra P.1 (AUTHOR) rgupta4@uottawa.ca
Publikováno v:
Universe (2218-1997). Jun2024, Vol. 10 Issue 6, p266. 21p.
Autor:
Gupta, Rajendra P.
Publikováno v:
Astroparticle Physics (2021) 129, 102578
We have used the recently published varying physical constants (VPC) approach to resolve the primordial lithium abundance problem. The value of the ratio of $7Li$ to hydrogen $7Li/H=1.400(\pm 0.023){\times}10^{-10}$ we have calculated using this appr
Externí odkaz:
http://arxiv.org/abs/2010.13628