Gravitational lensing limits on the cosmological constant in a flat universe

1990 ◽  
Vol 365 ◽  
pp. L43 ◽  
Author(s):  
Edwin L. Turner
Keyword(s):  
Cosmological Constant ◽  
Gravitational Lensing ◽  
Flat Universe

scholarly journals SNe Ia Redshift in a Nonadiabatic Universe

Universe ◽  
2018 ◽  
Vol 4 (10) ◽  
pp. 104 ◽  
Author(s):  
Rajendra Gupta
Keyword(s):  
Cosmological Constant ◽  
Deceleration Parameter ◽  
Hubble Constant ◽  
Cosmological Models ◽  
Single Parameter ◽  
New Approach ◽  
Cosmological Principle ◽  
Flat Universe ◽  
Λcdm Model ◽  
Two Parameters

By relaxing the constraint of adiabatic universe used in most cosmological models, we have shown that the new approach provides a better fit to the supernovae Ia redshift data with a single parameter, the Hubble constant H0, than the standard ΛCDM model with two parameters, H0 and the cosmological constant Λ related density, ΩΛ. The new approach is compliant with the cosmological principle. It yields the H0 = 68.28 (±0.53) km s−1 Mpc−1 with an analytical value of the deceleration parameter q0 = −0.4. The analysis presented is for a matter-only, flat universe. The cosmological constant Λ may thus be considered as a manifestation of a nonadiabatic universe that is treated as an adiabatic universe.

scholarly journals Extreme gravitational lensing in vicinity of Schwarzschild-de Sitter black holes

Open Physics ◽  
2007 ◽  
Vol 5 (4) ◽  
Author(s):  
Pavel Bakala ◽  
Petr Čermák ◽  
Stanislav Hledík ◽  
Zdeněk Stuchlík ◽  
Kamila Truparová
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Gravitational Lensing ◽  
High Performance ◽  
Computer Code ◽  
De Sitter ◽  
Simulation Code ◽  
Black Hole Spacetimes ◽  
Optical Projection ◽  
Free Falling

AbstractWe have developed a realistic, fully general relativistic computer code to simulate optical projection in a strong, spherically symmetric gravitational field. The standard theoretical analysis of optical projection for an observer in the vicinity of a Schwarzschild black hole is extended to black hole spacetimes with a repulsive cosmological constant, i.e, Schwarzschild-de Sitterspacetimes. Influence of the cosmological constant is investigated for static observers and observers radially free-falling from the static radius. Simulations include effects of the gravitational lensing, multiple images, Doppler and gravitational frequency shift, as well as the intensity amplification. The code generates images of the sky for the static observer and a movie simulations of the changing sky for the radially free-falling observer. Techniques of parallel programming are applied to get a high performance and a fast run of the BHC simulation code.

scholarly journals Deflection of light around a rotating BTZ black hole

2020 ◽  
Vol 35 (39) ◽  
pp. 2050323
Author(s):  
Shubham Kala ◽  
Hemwati Nandan ◽  
Prateek Sharma
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Test Particle ◽  
Gravitational Lensing ◽  
Critical Parameters ◽  
Btz Black Hole ◽  
Bending Angle ◽  
Retrograde Motion ◽  
Test Particles ◽  
Dimensional Gravity

We present a detailed study of gravitational lensing around a rotating Bañados–Teitelboim–Zanelli (BTZ) black hole in (2 + 1)-dimensional gravity. The study of orbits for massless test particle around this BH spacetime is performed to describe the nature of cosmological constant in lower dimensions. We study the effect of cosmological constant on the photon orbit in view of other critical parameters. The bending angle of light is studied in view of different values of cosmological constant for direct and retrograde motion of test particles. It is being observed that the bending angle slightly decreases as the value of cosmological constant increases in the negative region.

scholarly journals Global Dynamics of the Hořava–Lifshitz Cosmological Model in a Non-Flat Universe with Non-Zero Cosmological Constant

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 445
Author(s):  
Fabao Gao ◽  
Jaume Llibre
Keyword(s):  
Differential Equations ◽  
Cosmological Model ◽  
Cosmological Constant ◽  
Qualitative Theory ◽  
Global Dynamics ◽  
Model Based ◽  
Flat Universe

When the cosmological constant is non-zero, the dynamics of the cosmological model based on Hořava–Lifshitz gravity in a non-flat universe are characterized by using the qualitative theory of differential equations.

Quasar populations in a cosmological constant-dominated flat universe

1995 ◽  
Vol 445 ◽  
pp. 553 ◽  
Author(s):  
Sangeeta Malhotra ◽  
Edwin L. Turner
Keyword(s):  
Cosmological Constant ◽  
Flat Universe

CONSTRAINT ON THE COSMOLOGICAL CONSTANT FROM GRAVITATIONAL LENSING IN AN EVOLUTIONARY MODEL OF GALAXIES

1998 ◽  
Vol 13 (24) ◽  
pp. 4227-4236 ◽  
Author(s):  
DEEPAK JAIN ◽  
N. PANCHAPAKESAN ◽  
S. MAHAJAN ◽  
V. B. BHATIA
Keyword(s):  
Cosmological Constant ◽  
Galaxy Evolution ◽  
Optical Depth ◽  
Gravitational Lensing ◽  
Statistical Study ◽  
Evolutionary Model ◽  
Building Blocks ◽  
Lens Model ◽  
Gravitational Lenses ◽  
Luminosity Evolution

We study the effect of the cosmological constant on the statistical properties of gravitational lenses in flat cosmologies (Ω0+λ0=1). It is shown that some of the lens observables are strongly affected by the cosmological constant, especially in a low-density universe, and its existence might be inferred by a statistical study of the lenses. In particular, the optical depth of the lens distribution may be used best for this purpose without depending much on the lens model. We calculate the optical depth (probability of a beam encountering a lens event) for a source in a new picture of galaxy evolution based on number evolution in addition to pure luminosity evolution. It seem that present-day galaxies result from the merging of a large number of building blocks. We have tried to put a limit on the cosmological constant in this new picture of galaxy evolution. This evolutionary model of galaxies permits a larger value of the cosmological constant.

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