Keyword

cosmology

5 papers tagged “cosmology”

PhysicsNature · Jul 2024 Open access

Spectroscopic confirmation of two luminous galaxies at a redshift of 14

Stefano Carniani

Using JWST/NIRSpec observations from the JWST Advanced Deep Extragalactic Survey (JADES), the authors obtained spectroscopic confirmation of two unusually luminous galaxies, JADES-GS-z14-0 and JADES-GS-z14-1, at redshifts of about 14. These are among the most distant galaxies ever spectroscopically confirmed, existing roughly 290–300 million years after the Big Bang. Their brightness challenges pre-JWST models of how rapidly luminous galaxies could form in the early universe.

astrophysics cosmology early universe high-redshift galaxies

PhysicsThe Astrophysical Journal Letters · Jul 2022 Open access

A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km s−1 Mpc−1 Uncertainty from the Hubble Space Telescope and the SH0ES Team

Adam G. Riess

This SH0ES Team paper presents a refined local measurement of the Hubble constant using Hubble Space Telescope observations of Cepheid variables calibrating Type Ia supernovae. By expanding and improving the distance-ladder sample, the authors achieve roughly 1 km/s/Mpc total uncertainty. The result reinforces the significant tension with the Hubble constant inferred from the early-universe CMB.

hubble constant cosmology distance ladder cepheids

PhysicsAstronomy & Astrophysics · Sept 2020 Open access

Planck 2018 results. VI. Cosmological parameters

N. Aghanim, Y. Akrami and M. Ashdown

This paper presents the cosmological parameter constraints from the final (2018) Planck satellite analysis of cosmic microwave background temperature and polarization anisotropies plus lensing. The data are well fit by a six-parameter flat Lambda-CDM model, yielding precise values for the matter density, baryon density, and other parameters. The inferred Hubble constant from the CMB is in tension with local distance-ladder measurements.

cosmology cmb planck cosmological parameters

AstronomyThe Astrophysical Journal · Jul 1965 Open access

A Measurement of Excess Antenna Temperature at 4080 Mc/s

A. A. Penzias and R. W. Wilson

Penzias and Wilson reported that the 20-foot horn-reflector antenna at Bell Telephone Laboratories in Holmdel, New Jersey, measured an excess zenith antenna temperature of about 3.5 K at 4080 Mc/s (4.08 GHz) that could not be attributed to known sources of noise. They found this excess radiation to be isotropic, unpolarized, and free of seasonal variation within their measurement limits. In a companion paper, Dicke and colleagues interpreted this signal as relic radiation from a hot early universe, and it is now recognized as the discovery of the cosmic microwave background, providing key observational support for the Big Bang model.

cosmic microwave background big bang radio astronomy blackbody radiation

AstronomyProceedings of the National Academy of Sciences · Mar 1929 Open access

A Relation between Distance and Radial Velocity among Extra-Galactic Nebulae

Edwin Hubble

Hubble combined distances to roughly two dozen extra-galactic nebulae (galaxies), estimated largely from Cepheid variables and other stellar indicators, with their measured radial velocities to test for a systematic relationship. He found an approximately linear correlation in which the radial velocity of a nebula increases with its distance, with a proportionality constant of about 500 km/s per megaparsec. This velocity–distance relation, now known as Hubble's law, provided the first observational evidence that the universe is expanding and became a cornerstone of modern cosmology.

hubble's law expanding universe redshift extragalactic nebulae