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Many observations in recent times have shown evidence against the standard assumption of isotropy in the Big Bang model. Introducing a superhorizon scalar metric perturbation has been able to explain some of these anomalies. In this work,…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-21 Kaustav K. Das , Kishan Sankharva , Pankaj Jain

We use the Simon, Verde, & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain cosmological parameters in three dark energy cosmological models. We consider the standard $\Lambda$CDM model, the XCDM…

Astrophysics · Physics 2011-02-11 Lado Samushia , Bharat Ratra

Although bulk peculiar motions are commonplace in the universe, most theoretical studies either bypass them, or take the viewpoint of the idealised Hubble-flow observers. As a result, the role of these peculiar flows remains largely…

General Relativity and Quantum Cosmology · Physics 2021-09-24 C. G. Tsagas , M. I. Kadiltzoglou , K. Asvesta

An observer stationary with respect to comoving coordinates of the expanding universe should find the redshift distribution to be isotropic. However, a peculiar motion of the observer would introduce a dipole anisotropy in the observed…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-15 Ashok K. Singal

We examine the dark energy and matter densities allowed by precision measurements of distances out to various redshifts, in the presence of spatial curvature and (near) arbitrary behavior of the dark energy equation of state. Degeneracies…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-22 Arman Shafieloo , Eric V. Linder

The values of Hubble constant H0 by direct measurements with standard distance ladder are typically larger than those obtained from the observation of cosmic microwave background and the galaxy survey with inverse distance ladder. On the…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-26 Noriaki Kitazawa

A major issue in contemporary cosmology is the persistent discrepancy, known as the Hubble tension, between the Hubble constant ($H_0$) estimates from local measurements and those inferred from early-Universe observations under the standard…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-29 Surajit Kalita , Akhil Uniyal , Tomasz Bulik , Yosuke Mizuno

A major recent evelopment in observational cosmology has been an accurate measurement of the luminosity distance-redshift relation out to redshifts z=0.8 from Type Ia supernova standard candles. The results have been argued as evidence for…

Astrophysics · Physics 2016-01-13 Neil Trentham

The existence of critical points for the peculiar velocity field is a natural feature of the correlated vector field. These points appear at the junctions of velocity domains with different orientations of their averaged velocity vectors.…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-10 Hao Liu , Roya Mohayaee , Pavel Naselsky

Recent analyses of Cepheid distances to spiral galaxies have led to an announcement of a Hubble constant of $H_0 = 72 \pm 8$ km/sec/Mpc. The new Cepheid distances, however, show that there are numerous redshift distances with large excesses…

Astrophysics · Physics 2009-11-06 H. Arp

The success of precision cosmology depends not only on accurate observations, but also on the theoretical model - which must be understood to at least the same level of precision. Subtle relativistic effects can lead to biased measurements…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-23 Chris Clarkson , Obinna Umeh , Roy Maartens , Ruth Durrer

In order to keep pace with the increasing data quality of astronomical surveys the observed source redshift has to be modeled beyond the well-known Doppler contribution. In this letter I want to examine the gauge issue that is often glossed…

General Relativity and Quantum Cosmology · Physics 2018-02-01 Julian Adamek

We extract the Hubble law by the frequency-shift considerations of test particles revolving the Kerr black hole in asymptotically de Sitter spacetime. To this end, we take into account massive geodesic particles circularly orbiting the…

General Relativity and Quantum Cosmology · Physics 2023-05-29 Mehrab Momennia , Alfredo Herrera-Aguilar , Ulises Nucamendi

In a series of articles, we have shown that the newly discovered plasma-redshift cosmology gives a simpler, more accurate and consistent explanation of many cosmological phenomena than the big-bang cosmology. The SNe Ia observations are in…

Astrophysics · Physics 2007-05-23 Ari Brynjolfsson

Knowing the late time evolution of the Universe and finding out the causes for this evolution are the important challenges of modern cosmology. In this work, we adopt a model-independent cosmographic approach and approximate the Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-23 Salvatore Capozziello , Ruchika , Anjan A Sen

Experimental tests of homogeneous-universe classical standpoint cosmology are proposed after presentation of conceptual considerations that encourage this radical departure from the standard model. Among predictions of the new model are…

General Relativity and Quantum Cosmology · Physics 2007-05-23 G. F. Chew

The existence of 'peculiar' velocities due to the formation of cosmic structure marks a point of discord between the real Universe and the usually assumed Friedmann-Lema\'{i}tre-Robertson-Walker metric which accomodates only the smooth…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-09 Roya Mohayaee , Mohamed Rameez , Subir Sarkar

The three-dimensional distribution of astronomical objects observed in redshift space significantly differs from the true distribution since the distance to each object cannot be determined by its redshift $z$ only; for $z \ll 1$ the…

Astrophysics · Physics 2008-11-26 Yasushi Suto , Hiromitsu Magira , Y. P. Jing , Takahiko Matsubara , Kazuhiro Yamamoto

The cosmic expansion history, mapped by the Hubble parameter as a function of redshift, offers the most direct probe of the dark energy equation of state. One way to determine the Hubble parameter at different redshifts is essentially…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-11 Youhua Xu , Hu Zhan , Yeuk-Kwan Edna Cheung

According to astrophysical observations value of recession velocity in a certain point is proportional to a distance to this point. The proportionality coefficient is the Hubble constant measured with 5% accuracy. It is used in many…

General Physics · Physics 2017-06-16 Zeinulla Zhanabaev , Serik Khokhlov , Aldiyar Agishev
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