Results 21 to 30 of about 727,203 (295)

Constraints on holographic dark energy models using the differential ages of passively evolving galaxies [PDF]

, 2007
Using the absolute ages of passively evolving galaxies observed at different redshifts, one can obtain the differential ages, the derivative of redshift $z$ with respect to the cosmic time $t$ (i.e. ${\rm d} z/{\rm d}t$). Thus, the Hubble parameter $H(z)$
Abraham R. G., Alam U., Huang Q. G., Peiris H. V., Riess A. G., TONG-JIE ZHANG, ZE-LONG YI   +6 more
core   +1 more source

Structure of the Baryon Halo Around a Supermassive Primordial Black Hole

Particles
According to some theoretical models, primordial black holes with masses of more than 108 solar masses could be born in the early universe, and their possible observational manifestations have been investigated in a number of works. Dense dark matter and
Boris Murygin, Viktor Stasenko, Yury Eroshenko   +2 more
doaj   +1 more source

Searching for the dark force with 21-cm spectrum in light of EDGES

Physics Letters B, 2019
The EDGES Collaboration has recently announced the detection of the 21-cm spectrum with an absorption profile centred at 78 megahertz, of which the depth is deeper than that expected by the standard cosmological paradigm. To enrich the heating process of
Chunlong Li, Yi-Fu Cai
doaj   +1 more source

Possible combinations of early and late time cosmologies through BAO scales

European Physical Journal C: Particles and Fields, 2023
The theoretical scenarios of early universe and late time accelerated expansion constitute an open problem in cosmology. Relative Baryon Acoustic Oscillation (BAO) scales measured by 6dFGS, $$\mathrm SDSS+2dFGRS$$ S D S S + 2 d F G R S , BOSS DR11 Ly ...
Sanjeev Kalita, Chayanika Rabha
doaj   +1 more source

The bispectrum of redshifted 21-cm fluctuations from the dark ages [PDF]

, 2006
Brightness-temperature fluctuations in the redshifted 21-cm background from the cosmic dark ages are generated by irregularities in the gas-density distribution and can then be used to determine the statistical properties of density fluctuations in the ...
Ali S., Annalisa Pillepich, Cristiano Porciani, Field G. B., Sabino Matarrese, Scott D.   +5 more
core   +2 more sources

Detecting the signature of helium reionization through 3HeII 3.46 cm line-intensity mapping

Astronomy & Astrophysics
Context. Helium reionization is the most recent phase change of the intergalactic medium, yet its timing and main drivers remain uncertain. Among the probes to trace to trace how it unfolds, the 3.46 cm hyperfine line of singly ionized helium has opened ...
Spina Benedetta, Porciani Cristiano, Bosman Sarah E. I., Davies Frederick B., Garaldi Enrico, Keenan Ryan P., Schimd Carlo   +6 more
doaj   +1 more source

Aging and dark adaptation

Vision Research, 1999
Older adults have serious difficulty seeing under low illumination and at night, even in the absence of ocular disease. Optical changes in the aged eye, such as pupillary miosis and increased lens density, cannot account for the severity of this problem, and little is known about its neural basis.
Jackson, Gregory R., Owsley, Cynthia, McGwin, Gerald   +2 more
openaire   +2 more sources

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

, 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.
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
core   +1 more source

Lyα visibility from z = 4.5 to 11 in the UDS field: Evidence for a high neutral hydrogen fraction and small ionized bubbles at z ∼ 7

Astronomy & Astrophysics
The resonant scattering nature of Lyα photons interacting with neutral hydrogen makes Lyα emitters (LAEs) robust tracers of the intergalactic neutral hydrogen fraction, and thus sensitive probes of cosmic reionization.
Napolitano L., Pentericci L., Dickinson M., Arrabal Haro P., Taylor A. J., Calabrò A., Bhagwat A., Santini P., Arevalo-Gonzalez F., Begley R., Castellano M., Ciardi B., Donnan C. T., Dottorini D., Dunlop J. S., Finkelstein S. L., Fontana A., Giavalisco M., Hirschmann M., Jung I., Koekemoer A. M., Kokorev V., Llerena M., Lucas R. A., Mascia S., Merlin E., Pérez-González P. G., Stanton T. M., Tripodi R., Wang X., Weiner B. J.   +30 more
doaj   +1 more source

Irish and Welsh Law in the European Contexts

Clio@Themis, 2021
This paper traces the relationship of the Roman Empire with Ireland and Wales from roughly the fifth to the seventh centuries and probes the role that Roman and Canon law played there following the events of 410, based on evidence from authors, such as ...
Thomas Charles-Edward, Jaqueline Bemmer
doaj   +1 more source