scholarly journals The Acceleration of the Expansion of the Universe: A Brief Early History of the Supernova Cosmology Project (SCP)

2009 ◽  
Author(s):  
Gerson Goldhaber ◽  
David B. Cline
Keyword(s):  
Early History ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

scholarly journals Displaced new physics at colliders and the early universe before its first second

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Francesco D’Eramo ◽  
Sam Junius ◽  
Laura Lopez-Honorez ◽  
Alberto Mariotti
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Upper Bound ◽  
New Physics ◽  
Early History ◽  
Relic Density ◽  
History Of ◽  
Indirect Information ◽  
The Universe

Abstract Displaced vertices at colliders, arising from the production and decay of long-lived particles, probe dark matter candidates produced via freeze-in. If one assumes a standard cosmological history, these decays happen inside the detector only if the dark matter is very light because of the relic density constraint. Here, we argue how displaced events could very well point to freeze-in within a non-standard early universe history. Focusing on the cosmology of inflationary reheating, we explore the interplay between the reheating temperature and collider signatures for minimal freeze-in scenarios. Observing displaced events at the LHC would allow to set an upper bound on the reheating temperature and, in general, to gather indirect information on the early history of the universe.

Gamma-Ray Bursts as Probes of the Universe

2011 ◽  
Author(s):  
Joshua S. Bloom
Keyword(s):  
Star Formation ◽  
Cosmic Rays ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Ongoing Study ◽  
Observable Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact about GRBs that makes them such great probes is that they are fantastically bright and so can be seen to the farthest reaches of the observable Universe. In parallel with the ongoing study of GRB events and progenitors, new lines of inquiry have burgeoned: using GRBs as unique probes of the Universe in ways that are almost completely divorced from the nature of GRBs themselves. Topics discussed include studies of gas, dust, and galaxies; the history of star formation; measuring reionization and the first objects in the universe; neutrinos, gravitational waves, and cosmic rays; quantum gravity and the expansion of the universe; and the future of GRBs.

scholarly journals High Redshift Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 571-576
Author(s):  
K. Meisenheimer ◽  
H. Hippelein ◽  
M. Neeser
Keyword(s):  
Radio Emission ◽  
Electromagnetic Waves ◽  
High Redshift ◽  
Radio Galaxies ◽  
Early History ◽  
Radio Telescopes ◽  
Radio Waves ◽  
History Of ◽  
The Universe ◽  
Travel Distances

One hundred years after G. Marconi recorded radio waves over a distance of more than 1000 m, the most sensitive radio telescopes are able to detect the radio emission from light travel distances at least 1.4 × 1023 times greater. The electromagnetic waves from these distant objects are red shifted by Δλ/λ = z > 4. It is not the mere distance of high redshift objects which is fascinating, but rather the fact that one looks back into the early history of the universe by observing them: Objects at a redshift of 4 shined at a time when the universe had reached only about 1/5 of its present age.

Cosmological distances scale: Part 10. The global Anisotropy

2020 ◽  
pp. 9-25
Author(s):  
S. F. Levin
Keyword(s):  
Distance Scale ◽  
Accelerated Expansion ◽  
Cosmological Distance Scale ◽  
Cosmological Distance ◽  
Measurement Tools ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

A brief overview of the history of the origin and development of the cosmological distance scale based on redshift is given. Statistical aspects of the problem of calibration of scales of this type are considered and their analogy with the problems of calibration of measurement tools is shown. The analysis of the first data on the basis of which the “accelerated expansion of the Universe” was detected. The Consequences of Anisotropy for Distance Scale is analyzed.

Allan Rex Sandage. 18 June 1926 — 13 November 2010

2012 ◽  
Vol 58 ◽  
pp. 245-264 ◽  
Author(s):  
Donald Lynden-Bell ◽  
François Schweizer
Keyword(s):  
Stellar Evolution ◽  
Star Clusters ◽  
Optical Telescope ◽  
Elemental Abundances ◽  
Mount Wilson Observatory ◽  
History Of ◽  
Expansion Of The Universe ◽  
Edwin Hubble ◽  
Number Counts ◽  
The Universe

Allan Sandage was an observational astronomer who was happiest at a telescope. On the sudden death of Edwin Hubble, Sandage inherited the programmes using the world’s largest optical telescope at Palomar to determine the distances and number counts of galaxies. Over many years he greatly revised the distance scale and, on reworking Hubble’s analysis, discovered the error that had led Hubble to doubt the interpretation of the galaxies’ redshifts as an expansion of the Universe. Sandage showed that there was a consistent age of creation for the stars, the elements and the cosmos. Through work with Baade and Schwarzschild he discovered the key to the interpretation of the colour–magnitude diagrams of star clusters in terms of stellar evolution. With others he founded galactic archaeology, interpreting the motions and elemental abundances of the oldest stars in terms of a model for the Galaxy’s formation. He published several fine atlases and catalogues of galaxies and a definitive history of the Mount Wilson Observatory.

scholarly journals Accelerated expansion of the Universe in the presence of dark matter pressure

2020 ◽  
Vol 98 (2) ◽  
pp. 210-216
Author(s):  
Zeinab Rezaei
Keyword(s):  
Dark Matter ◽  
Equation Of State ◽  
Hubble Parameter ◽  
Energy Equation ◽  
Accelerated Expansion ◽  
Luminosity Distance ◽  
Modern Cosmology ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe

Expansion dynamics of the Universe is an important subject in modern cosmology. The dark energy equation of state determines these dynamics so that the Universe is in an accelerating phase. However, dark matter (DM) can also affect the accelerated expansion of the Universe through its equation of state. In the present work, we explore the expansion dynamics of the Universe in the presence of DM pressure. In this regard, applying the DM equation of state from the observational data related to the rotational curves of galaxies, we calculate the evolution of DM density. Moreover, the Hubble parameter, history of scale factor, luminosity distance, and deceleration parameter are studied while the DM pressure is taken into account. Our results verify that the DM pressure leads to higher values of the Hubble parameter at each redshift and the expansion of the Universe grows due to the DM pressure.

Deviations of R2 cosmology from the Einstein’s General Relativity

2020 ◽  
Vol 35 (36) ◽  
pp. 2044026
Author(s):  
E. V. Arbuzova
Keyword(s):  
General Relativity ◽  
Early Universe ◽  
Significant Influence ◽  
Particle Production ◽  
Cosmological Evolution ◽  
Evolution Of The Universe ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Einstein’S General Relativity

The cosmological history of the universe in the [Formula: see text] gravity is studied starting from the “very beginning” up to the present time. The primordial inflationary expansion of the universe is considered and it is shown that the gravitational particle production by the oscillating curvature, [Formula: see text], led to a consistent transition to the Friedmann cosmology, but the cosmological evolution in the early universe strongly differed from the standard one. It is shown that the effects of gravitational production of particles had a significant influence on the evolution of the universe.

A Brief History of Cosmology

2017 ◽  
Author(s):  
John Iliopoulos
Keyword(s):  
Big Bang ◽  
Modern Theory ◽  
Microwave Background ◽  
Detailed Measurement ◽  
New Concepts ◽  
History Of Cosmology ◽  
History Of ◽  
Expansion Of The Universe ◽  
The Big Bang ◽  
The Universe

We present the evolution of our ideas concerning the history of the Cosmos. They are based on Einstein’s theory of General Relativity in which E.P. Hubble and G. Lemaître brought two fundamental new concepts: the expansion of the Universe and the model of the Big Bang. They form the basic elements of the modern theory of Cosmology. We present very briefly the observational evidence which corroborates this picture based on a vast amount of data, among which the most recent ones come from the Planck mission with a detailed measurement of the cosmic microwave background (CMB) radiation. We show that during its evolution the Universe went through several phase transitions giving rise to the formation of particles, atoms, nuclei, etc. A particular phase transition, which occurred very early in the cosmic history, around 10–12 seconds after the Big Bang, is the Brout–Englert–Higgs (BEH) transition during which a fraction of the energy was transformed into mass, thus making it possible for most elementary particles to become massive.

scholarly journals Observations of Diffuse IR Background Radiation by IRTS and IRIS

1996 ◽  
Vol 168 ◽  
pp. 117-124 ◽  
Author(s):  
H. Okuda
Keyword(s):  
Background Radiation ◽  
Cosmic Background Radiation ◽  
Early History ◽  
Cosmic Background ◽  
Diffuse Background ◽  
History Of ◽  
The Universe

Diffuse background radiation is integrated light which is consisted of various components of interplanetary, stellar, interstellar, galactic and intergalactic origins as well as cosmic background radiation, the remnant of the pre-galactic phenomena in the early history of the universe.

scholarly journals Variable G versus the Accelerated Expansion of the Universe

2017 ◽  
Vol 26 (1) ◽  
pp. 293-296
Author(s):  
Bernard G. Colenbrander ◽  
Willem S. Hulscher
Keyword(s):  
Dark Matter ◽  
Local Density ◽  
Accelerated Expansion ◽  
Astronomical Observations ◽  
History Of ◽  
Expansion Of The Universe ◽  
Valid Evidence ◽  
Newtonian Constant ◽  
The Universe ◽  
Variable G

Abstract It is shown that the hypothesis of permitting variability of the Newtonian constant G, increasing with the local density of dark matter, implies that there is no need for the introduction of a cosmological constant or accelerated expansion of the universe. A higher value of G in the younger universe leads to an enhanced redshift of the spectra from e.g. supernovae, which results in an estimation of a larger distance and magnitude. Interpreting relevant astronomical observations in terms of both effects leads remarkably to a linear relationship between the redshift and the magnitude of the supernovae throughout the history of the universe. Furthermore it is shown, that from CMB measurements, no reliable conclusions can be drawn about the structure and geometry of the universe. It is concluded that, if the hypothesis survives further tests, no valid evidence is available that would point to an accelerated expansion of the universe and therefore it is not necessary to assume the existence of dark energy.

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