Results 1 to 10 of about 664,223 (186)

Violence in the Dark Ages [PDF]

The Astrophysical Journal, 2002
A wide range of observational and theoretical arguments suggest that the universe experienced a period of heating and metal enrichment, most likely from starbursting dwarf galaxies. Using a hydrodynamic simulation we have conducted a uniquely detailed theoretical investigation of this epoch at the end of the cosmological ``dark ages''.
Marc Davis, Evan Scannapieco, Robert J. Thacker, Robert J. Thacker   +3 more
core   +5 more sources

Galaxies into the Dark Ages [PDF]

The Astrophysical Journal, 2017
Abstract We consider the capabilities of current and future large facilities operating at 2–3 mm wavelength to detect and image the [C ii] 158 μm line from galaxies into the cosmic “dark ages” (z ∼ 10–20). The [C ii] line may prove to be a powerful tool in determining spectroscopic redshifts, and galaxy dynamics, for the first galaxies ...
Andrea Ferrara, Chris Carilli, Chris Carilli, Pratika Dayal, Eric J. Murphy   +4 more
openaire   +6 more sources

Dark energy in the dark ages [PDF]

Astroparticle Physics, 2006
Non-negligible dark energy density at high redshifts would indicate dark energy physics distinct from a cosmological constant or ``reasonable'' canonical scalar fields. Such dark energy can be constrained tightly through investigation of the growth of structure, with limits of \la2% of total energy density at z\gg1 for many models.
Abazajian, Caldwell, Dodelson, Doran, Doran, Eric V. Linder, Fry, Linder, Linder, Linder, Linder, Linder, Linder, Linder, Seljak, Wetterich   +15 more
openaire   +7 more sources

A smoother end to the dark ages [PDF]

, 2011
Independent lines of evidence suggest that the first stars, which ended the cosmic dark ages, came in pairs, rather than singly. This could change the prevailing view that the early Universe had a Swiss-cheese-like appearance.
A Stacy, A Venkatesan, IF Mirabel, M Dijkstra, M Ricotti, MJ Turk, P Madau, SCO Glover, SP Oh, SR Furlanetto, T Abel, V Bromm, X Chen, Z Haiman, Z Haiman, Zoltán Haiman   +15 more
arxiv   +3 more sources

Constraints on the cosmic equation of state: age conflict versus phantom energy. Age-redshift relations in an accelerated universe [PDF]

Astron.Astrophys. 422 (2004) 831-839, 2004
The currently available values and confidence limits for Omega_m0, H_0 and globular cluster ages still indicate that the dark energy that dominates the Universe could also be a form of quintessence or phantom energy. In fact, current cosmological values favor phantom energy.
Aurich, Bolte, Caldwell, Carlberg, Carretta, Carroll, Cline, de Bernardis, del Popolo, Doran, Doran, Fassnacht, Freedman, Goliath, González-Díaz, Hu, Kneller, Knox, Krauss, Linder, Mauskopf, Parodi, Perlmutter, Ratra, Reichart, Riess, Riess, Spergel, Thomas, Turner, van den Bergh, Waga, Wetterich   +32 more
arxiv   +3 more sources

Particle decays during the cosmic dark ages [PDF]

, 2004
We consider particle decays during the cosmic dark ages with two aims: (1) to explain the high optical depth reported by the Wilkinson Microwave Anisotropy Probe (WMAP), and (2) to provide new constraints to the parameter space for decaying particles. We
Xuelei Chen, Marc Kamionkowski
openalex   +5 more sources

Indirect Dark Matter Signatures in the Cosmic Dark Ages I. Generalizing the Bound on s-wave Dark Matter Annihilation from Planck [PDF]

Phys. Rev. D 93, 023527 (2016), 2015
Recent measurements of the cosmic microwave background (CMB) anisotropies by Planck provide a sensitive probe of dark matter annihilation during the cosmic dark ages, and specifically constrain the annihilation parameter $f_\mathrm{eff} \langle \sigma v \rangle/m_\chi$.
Slatyer, Tracy R.
arxiv   +5 more sources

After the dark ages*

Journal of Physics A: Mathematical and Theoretical, 2022
Abstract After recalling some puzzles in cosmology and briefly reviewing the Friedmann–Lemaître cosmos a simple unified model of the ‘dark sector’ is described. This model involves a scalar field and a pseudo-scalar axion field that give rise to dark energy in the form of ‘quintessence’ and to ‘fuzzy’ dark matter, respectively ...
Fröhlich, Jürg
openaire   +3 more sources

Alleviation of Cosmic Age Problem In Interacting Dark Energy Model [PDF]

Phys. Lett. B 669 (2008) 201, 2008
We investigate the cosmic age problem associated with the old high-$z$ quasar APM 08279 + 5255 and the oldest globular cluster M 107, both being difficult to accommodate in $\Lambda$CDM model. By evaluating the age of the Universe in a model that has an extremely phantom like form of dark energy (DE), we show that simply introducing the dark energy ...
Shuang Wang, Y. Zhang
arxiv   +3 more sources

The Dark Age in Africa [PDF]

Nature, 1960
Old Africa Rediscovered By Basil Davidson. Pp. 287 + 28 plates. (London: Victor Gollancz, Ltd., 1959.) 25s. net.
M. C. Burkitt
openaire   +3 more sources