scholarly journals Manifestations of dark energy in the dynamics of the Solar system

2009 ◽  
Vol 5 (S264) ◽  
pp. 410-412
Author(s):  
Michal Křížek ◽  
Jan Brandts
Keyword(s):  
Dark Energy ◽  
Solar System ◽  
Hubble Constant ◽  
The Sun ◽  
Expansion Speed ◽  
Current Value ◽  
The Impact ◽  
The Universe

AbstractThe expansion speed of the Universe is increasing (Glanz 1998). This acceleration is attributed to dark energy which acts almost uniformly everywhere (including the Solar system) and thus essentially influences the Hubble constant. Its current value on a distance of 1 AU is H0 = 10 m/(yr AU). This is quite a large number and thus, the impact of dark energy should be detectable in the Solar system. We will illustrate it by several examples. Dark energy may partially be caused by gravitational aberration of the Sun, planets and other bodies.

scholarly journals Gravitational polarization of the quantum vacuum caused by two point-like bodies

2021 ◽  
Vol 503 (4) ◽  
pp. 5091-5099
Author(s):  
Dragan Slavkov Hajdukovic ◽  
Sergej Walter
Keyword(s):  
Dark Matter ◽  
Solar System ◽  
Charge Density ◽  
Numerical Method ◽  
Quantum Vacuum ◽  
Body System ◽  
Complex Fluid ◽  
The Impact ◽  
The Universe ◽  
Gravitational Charge

ABSTRACT In a recent paper, quantum vacuum was considered as a source of gravity, and the simplest, phenomenon, the gravitational polarization of the quantum vacuum by an immersed point-like body, was studied. In this paper, we have derived the effective gravitational charge density of the quantum vacuum, caused by two immersed point-like bodies. Among others, the obtained result proves that quantum vacuum can have regions with a negative effective gravitational charge density. Hence, quantum vacuum, the ‘ocean’ in which all matter of the Universe is immersed, acts as a complex fluid with a very variable gravitational charge density that might include both positive and negative densities; a crucial prediction that can be tested within the Solar system. In the general case of ${N \ge {\rm{3}}}$ point-like bodies, immersed in the quantum vacuum, the analytical solutions are not possible, and the use of numerical methods is inevitable. The key point is that an appropriate numerical method, for the calculation of the effective gravitational charge density of the quantum vacuum induced by N immersed bodies, might be crucial in description of galaxies, without the involvement of dark matter or a modification of gravity. The development of such a valuable numerical method, is not possible, without a previous (and in this study achieved) understanding of the impact of a two-body system.

scholarly journals The s-process in stellar sites

2018 ◽  
Vol 184 ◽  
pp. 01004
Author(s):  
Sergio Cristallo
Keyword(s):  
Solar System ◽  
Neutron Capture ◽  
Slow Neutron ◽  
Heavy Elements ◽  
The Sun ◽  
Capture Process ◽  
The Universe ◽  
Pollution Episodes

Stars are marvellous caldrons where all the elements of the Universe (apartfrom hydrogen and helium) have been synthesized. The solar system chemical distri-butionis the result of many pollution episodes from already extinct stellar generations, occurred at different epochs before the Sun formation. Main nucleosynthesis channels re-sponsiblefor the formation of heavy elements are the rapid neutron capture process (ther-process) and the slow neutron capture process (the s-process). Hereafter, I will describethe theory of the s-process and the stellar sites where it is active.

scholarly journals The dark sector cosmology

2020 ◽  
Vol 29 (14) ◽  
pp. 2030014
Author(s):  
Elcio Abdalla ◽  
Alessandro Marins
Keyword(s):  
Dark Energy ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Acoustic Oscillations ◽  
Dark Sector ◽  
Fundamental Physics ◽  
Observational Techniques ◽  
Distance Indicators ◽  
The Universe ◽  
Theoretical Developments

The most important problem in fundamental physics is the description of the contents of the Universe. Today, we know that 95% thereof is totally unknown. Two thirds of that amount is the mysterious Dark Energy described in an interesting and important review [E. J. Copeland, M. Sami and S. Tsujikawa, Int. J. Mod. Phys. D 15 (2006) 1753]. We briefly extend here the ideas contained in that review including the more general Dark Sector, that is, Dark Matter and Dark Energy, eventually composing a new physical Sector. Understanding the Dark Sector with precision is paramount for us to be able to understand all the other cosmological parameters comprehensively as modifications of the modeling could lead to potential biases of inferred parameters of the model, such as measurements of the Hubble constant and distance indicators such as the Baryon Acoustic Oscillations. We discuss several modern methods of observation that can disentangle the different possible descriptions of the Dark Sector. The possible applications of some theoretical developments are also included in this paper as well as a more thorough evaluation of new observational techniques at lower frequencies and gravitational waves.

The Odd Couple: Quasars & Black Holes

Daedalus ◽  
2014 ◽  
Vol 143 (4) ◽  
pp. 103-113 ◽  
Author(s):  
Scott Tremaine
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Solar System ◽  
Total Mass ◽  
Host Galaxy ◽  
The Sun ◽  
Central Black Hole ◽  
Frictional Forces ◽  
The Universe

Quasars emit more energy than any other object in the universe, yet are not much bigger than our solar system. Quasars are powered by giant black holes of up to ten billion (1010) times the mass of the sun. Their enormous luminosities are the result of frictional forces acting upon matter as it spirals toward the black hole, heating the gas until it glows. We also believe that black holes of one million to ten billion solar masses – dead quasars – are present at the centers of most galaxies, including our own. The mass of the central black hole appears to be closely related to other properties of its host galaxy, such as the total mass in stars, but the origin of this relation and the role that black holes play in the formation of galaxies are still mysteries.

scholarly journals Abundances of hydrogen and helium isotopes in the Protosolar Cloud

2009 ◽  
Vol 5 (S268) ◽  
pp. 71-79 ◽  
Author(s):  
Johannes Geiss ◽  
George Gloeckler
Keyword(s):  
Solar Wind ◽  
Solar System ◽  
Big Bang ◽  
The Sun ◽  
Density Profiles ◽  
Origin And Evolution ◽  
Naturally Occurring ◽  
System 2 ◽  
The Big Bang ◽  
The Universe

AbstractFor our understanding of the origin and evolution of baryonic matter in the Universe, the Protosolar Cloud (PSC) is of unique importance in two ways: 1) Up to now, many of the naturally occurring nuclides have only been detected in the solar system. 2) Since the time of solar system formation, the Sun and planets have been virtually isolated from the galactic nuclear evolution, and thus the PSC is a galactic sample with a degree of evolution intermediate between the Big Bang and the present.The abundances of the isotopes of hydrogen and helium in the Protosolar Cloud are primarily derived from composition measurements in the solar wind, the Jovian atmosphere and “planetary noble gases” in meteorites, and also from observations of density profiles inside the Sun. After applying the changes in isotopic and elemental composition resulting from processes in the solar wind, the Sun and Jupiter, PSC abundances of the four lightest stable nuclides are given.

scholarly journals A combined analysis of the H0 late time direct measurements and the impact on the Dark Energy sector

2021 ◽  
Vol 502 (2) ◽  
pp. 2065-2073
Author(s):  
Eleonora Di Valentino
Keyword(s):  
Dark Energy ◽  
Time Delay ◽  
Surface Brightness ◽  
Hubble Constant ◽  
New Physics ◽  
Late Time ◽  
Direct Measurements ◽  
Phantom Dark Energy ◽  
Surface Brightness Fluctuations ◽  
The Impact

ABSTRACT We combine 23 Hubble constant measurements based on Cepheids-SN Ia, TRGB-SN Ia, Miras-SN Ia, Masers, Tully Fisher, Surface Brightness Fluctuations, SN II, Time-delay Lensing, Standard Sirens and γ-ray Attenuation, obtaining our best optimistic H0 estimate, that is H0 = 72.94 ± 0.75 km s–1 Mpc–1 at 68 per cent CL. This is in 5.9σ tension with the ΛCDM model, therefore we evaluate its impact on the extended Dark Energy cosmological models that can alleviate the tension. We find more than 4.9σ evidence for a phantom Dark Energy equation of state in the wCDM scenario, the cosmological constant ruled out at more than 3σ in a w0waCDM model and more than 5.7σ evidence for a coupling between Dark Matter and Dark Energy in the IDE scenario. Finally, we check the robustness of our results; and we quote two additional combinations of the Hubble constant. The ultra-conservative estimate, H0 = 72.7 ± 1.1 km s–1 Mpc–1 at 68 per cent CL, is obtained removing the Cepheids-SN Ia and the Time-Delay Lensing based measurements, and confirms the evidence for new physics.

scholarly journals A dark energy quintessence model of the universe

2019 ◽  
Vol 35 (04) ◽  
pp. 2050002
Author(s):  
G. K. Goswami ◽  
Anirudh Pradhan ◽  
A. Beesham
Keyword(s):  
Dark Energy ◽  
Deceleration Parameter ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Time Dependent ◽  
Observational Constraints ◽  
History Of ◽  
Flrw Universe ◽  
The Universe ◽  
Quintessence Model

In this paper, we have presented a model of the Friedmann–Lemaitre–Robertson–Walker (FLRW) universe filled with matter and dark energy (DE) fluids by assuming an ansatz that deceleration parameter (DP) is a linear function of the Hubble constant. This results in a time-dependent DP having decelerating–accelerating transition phase of the universe. This is a quintessence model [Formula: see text]. The quintessence phase remains for the period [Formula: see text]. The model is shown to satisfy current observational constraints. Various cosmological parameters relating to the history of the universe have been investigated.

CAN w < -1 BE EXORCIZED?

2005 ◽  
Vol 14 (08) ◽  
pp. 1313-1320 ◽  
Author(s):  
PEDRO F. GONZÁLEZ-DÍAZ
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Constant ◽  
Phantom Energy ◽  
Current Value ◽  
The Universe

Dimming mechanisms based on the conversion of photons into axions have been recently suggested which could justify the observation of equation of state values w = P/ρ less than -1 that do not correspond to the presence of phantom energy in the universe. It is argued that, though such a mechanism may in fact increase the actual value of w, it does not actually solve the phantom problem because the produced axions precisely are of the kind which has been considered to make up phantom energy and therefore the suggested mechanism can never make the actual value of w to exactly reach the value -1 from below, such as it also happens with other suggested mechanisms intended to get rid of phantoms from cosmology. It is conjectured that the actual current value of w must likely be less than -1 but so close to it that present observational accuracies could not allow discriminating between a cosmological constant and the phantom energy as the form currently taken by dark energy in the universe.

scholarly journals Local Large-Scale Structure and the Assumption of Homogeneity

2014 ◽  
Vol 11 (S308) ◽  
pp. 295-298 ◽  
Author(s):  
Ryan C. Keenan ◽  
Amy J. Barger ◽  
Lennox L. Cowie
Keyword(s):  
Dark Energy ◽  
Large Scale ◽  
Near Infrared ◽  
Mass Density ◽  
Hubble Constant ◽  
A Value ◽  
Accelerating Expansion ◽  
Luminous Matter ◽  
Local Measurements ◽  
The Universe

AbstractOur recent estimates of galaxy counts and the luminosity density in the near-infrared (Keenan et al. 2010, 2012) indicated that the local universe may be under-dense on radial scales of several hundred megaparsecs. Such a large-scale local under-density could introduce significant biases in the measurement and interpretation of cosmological observables, such as the inferred effects of dark energy on the rate of expansion. In Keenan et al. (2013), we measured the K-band luminosity density as a function of distance from us to test for such a local under-density. We made this measurement over the redshift range 0.01 < z < 0.2 (radial distances D ~ 50 - 800 h70−1 Mpc). We found that the shape of the K-band luminosity function is relatively constant as a function of distance and environment. We derive a local (z < 0.07, D < 300 h70−1 Mpc) K-band luminosity density that agrees well with previously published studies. At z > 0.07, we measure an increasing luminosity density that by z ~ 0.1 rises to a value of ~ 1.5 times higher than that measured locally. This implies that the stellar mass density follows a similar trend. Assuming that the underlying dark matter distribution is traced by this luminous matter, this suggests that the local mass density may be lower than the global mass density of the universe at an amplitude and on a scale that is sufficient to introduce significant biases into the measurement of basic cosmological observables. At least one study has shown that an under-density of roughly this amplitude and scale could resolve the apparent tension between direct local measurements of the Hubble constant and those inferred by Planck team. Other theoretical studies have concluded that such an under-density could account for what looks like an accelerating expansion, even when no dark energy is present.

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