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New method may resolve difficulty in measuring universe's expansion（图）
New method difficulty measuring universe
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2019/10/23
Astronomers using National Science Foundation radio telescopes have demonstrated how a combination of gravitational-wave and radio observations, along with theoretical modeling, can turn the mergers o...
The linear expansion hyperspherical universe
large scale structure of universe bolometric flux luminosity distance quasars galaxies redshift space redshift periodicity
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2011/9/25
From Karlsson’s formula and the polar effect, we realize that the half periodic parameter of redshift is 0.206, in theory, we finally explain why the great wall is at redshift Z=0.079 in redshift spac...
Hubble's law and faster than light expansion speeds
Hubble's law faster than light expansion speeds
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2011/10/14
Naively applying Hubble's law to a sufficiently distant object gives a receding velocity larger than the speed of light. By discussing a very similar situation in special relativity, we argue that Hub...
Peculiar motions, accelerated expansion and the cosmological axis
Peculiar motions accelerated expansion cosmological
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2011/10/12
Peculiar velocities change the expansion rate of any observer moving relative to the smooth Hubble flow. As a result, observers in a galaxy like our Milky Way can experience accelerated expansion with...
An effective theory of accelerated expansion
dark energy theory in ation
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2011/10/8
We work out an effective theory of accelerated expansion to describe general phenomena of inflation and acceleration (dark energy) in the Universe. Our aim is to determine from theoretical grounds, in...
Manifestly gauge invariant theory of the nonlinear cosmological perturbations in the leading order of the gradient expansion
nonlinear cosmological perturbation, gauge invariance, non-Gaussianity PACS number(s):98.80.Cq
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2011/9/29
In the full nonlinear cosmological perturbation theory in the leading order of the gradient expansion, all the types of the gauge invariant perturbation variables are defined. The metric junction cond...
Light propagation and the average expansion rate in near-FRW universes
Light propagation average expansion rate universes
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2011/9/29
We consider universes which are close to Friedmann-Robertson-Walker in the sense that metric perturbations, their time derivatives and first spatial derivatives are small, but second spatial derivativ...
Effective field theory for hydrodynamics: thermodynamics, and the derivative expansion
Effective field theory hydrodynamics:thermodynamics derivative expansion
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2011/10/14
We consider the low-energy effective field theory describing the infrared dynamics of non-dissipative fluids. We extend previous work to accommodate conserved charges, and we clarify the matching betw...
The influence of inhomogeneities on the large-scale expansion of the universe
influence of inhomogeneities large-scale expansion of the universe
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2010/11/12
The evolution of an inhomogeneous universe composed entirely of matter is followed from an early, nearly uniform state until the time when the inhomogeneities have begun to grow large. The particular ...
Forming Protostars in Molecular Clouds with Shocked Envelope Expansion and Core Collapse
ISM clouds — ISM individual (FeSt 1-457)— line: profiles — radiative transfer — stars
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2010/11/12
Spectral observations of molecular line profiles reveal the so-called ‘blue profiles’ for
double-peaked molecular lines with stronger blue and weaker red peaks as notable features for star-forming cl...
Probing the course of cosmic expansion with a combination of observational data
cosmic expansion combination of observational data
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2010/11/16
We study the cosmic expansion history by reconstructing the deceleration parameter q(z)
from the SDSS-II type Ia supernova sample (SNIa) with two different light curve fits (MLCS2k2
and SALT-II), th...
Constraining the expansion rate of the Universe using low-redshift ellipticals as cosmic chronometers
Cosmology and Extragalactic Astrophysics (astro-ph.CO)
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2010/12/24
We present a new methodology to determine the expansion history of the Universe analyzing the spectral properties of early type galaxies (ETG). We found that for these galaxies the 4000\AA break is a ...
Flare Ribbon Expansion and Energy Release
Sun activity—Sun flares chromosphere corona X-rays gamma rays
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2010/9/16
We report a detailed examination about the relationship between the evolution of the Hα flare ribbons and the released magnetic energy during the April 10 2001 flare. In the Hα images, several bright ...
Uniformity Despite Diversity：PN Expansion Velocities in the Local Group
PN Expansion Velocities Local Group
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2009/7/1
Uniformity Despite Diversity：PN Expansion Velocities in the Local Group。
Expansion Parallax for the Compact Planetary Nebula M2-43
Parallax Compact Planetary Nebula M2-43
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2009/6/30
Expansion Parallax for the Compact Planetary Nebula M2-43。