806 research outputs found
Two fundamental constants of gravity unifying the dark matter and the dark energy
The common nature of the dark sector - dark energy and dark matter - as shown
in [1] follows readily from the consideration of generalized Newtonian
potential as a weak-field General Relativity. That generalized potential
satisfying the Newton's theorem on the equivalence of sphere's gravity and that
of a point-mass located in its center, contains an additional constant which
along with the gravitational constant is able to explain quantitatively both
the dark energy (cosmological constant) and dark matter. So, gravity is defined
not by one but two fundamental constants. We show that, the second constant is
dimensional-independent and matter-uncoupled and hence is even more universal
than the gravitational constant, thus affecting the strategy of observational
studies of dark energy and of the search of dark matter.Comment: To appear in Eur Phys J C; 5 page
Gravity lens critical test for gravity constants and dark sector
The recent study of the strong gravitational lens ESO 325-G004 [1] leads to a
new possibility for testing General Relativity and its extensions. Such gravity
lens observational studies can be instrumental for establishing a limitation on
the precision of testing General Relativity in the weak-field regime and on the
two gravity constants (the Newtonian and cosmological ones) as described in
[2]. Namely, we predict a critical value for the involved weak-field parameter
\gamma_{cr}=0.998 (for M= 1.5 10^{11} M_{\odot} lens mass and r=2 kpc light
impact distance), which remarkably does not depend on any hypothetical variable
but is determined only by well measured quantities. If the critical parameter
\gamma_{cr} will be established at future observations, this will mark the
first discrepancy with General Relativity of conventional weak-field Newtonian
limit, directly linked to the nature of dark sector of the Universe.Comment: To appear in Eur Phys J C; 3 pages; minor revisio
The cosmological constant derived via galaxy groups and clusters
The common nature of dark matter and dark energy is argued in [1] based on
the approach that the cosmological constant \Lambda enters the weak-field
General Relativity following from Newton theorem on the "sphere-point mass"
equivalency [2]. Here we probe the \Lambda-gravity description of dark matter
in galaxy systems, from pairs up to galaxy clusters using the data of various
sources, i.e. of Local Supercluster galaxy surveys, gravity lensing and Planck
satellite. The prediction that the cosmological constant has to be the lower
limit for the weak-field \Lambda obtained from galaxy systems of various degree
of virialization is shown to be supported by those observations. The results
therefore support the \Lambda-gravity nature of dark matter in the studied
systems, implying that the positivity of the cosmological constant might be
deduced decades ago from the dynamics of galaxies and galaxy clusters far
before the cosmological SN surveys.Comment: To appear in Eur Phys J C, 7 page
Spectroscopy of Stellar-Like Objects Contained in the Second Byurakan Survey. I
The results of spectroscopic observations of 363 star-like objects from the
Second Byurakan Survey (SBS) are reported. This SBS's subsample has proven to
be a rich source of newly identified quasars, Seyfert type galaxies, degenerate
stars and hot subdwarfs. In the subsample here studied, we identified 35 new
QSOs, 142 White Dwarfs (WDs) the majority of which, 114 are of DA type, 55
subdwarfs (29 of which are sdB-type stars), 10 HBB, 16 NHB, 54 G-type and 25
F-type stars, two objects with composite spectra, four Cataclismic Variables
(CV), two peculiar emission line stars, 17 objects with continuous spectra, as
well as one planetary nebula. Among the 35 QSOs we have found two Broad
Absorption Line (BAL) QSOs, namely SBS 1423+500 and SBS 1435+500A. Magnitudes,
redshifts, and slit spectra for all QSOs, also some typical spectra of the
peculiar stars are presented. We estimate the minimum surface density of bright
QSOs in redshift range 0.3<z<2.2 to be 0.05 per sq. deg. for B<17.0 and 0.10
per sq. deg. for B<17.5.Comment: 22 pages, 3 tables, 4 figures, PASP in pres
An example of the stochastic dynamics of a causal set
An example of a discrete pregeometry on a microscopic scale is introduced.
The model is a directed dyadic acyclic graph. This is the particular case of a
causal set. The particles in this model must be self-organized repetitive
structures. The dynamics of this model is a stochastic sequential growth
dynamics. New vertexes are added one by one. The probability of this addition
depends on the structure of existed graph. The particular case of the dynamics
is considered. The numerical simulation provides some symptoms of
self-organization.Comment: 7 pages, 5 figures, work presented at the conference "Foundations of
Probability and Physics-6" (FPP6) held on 12-15 June 2011 at the Linnaeus
University, V\"axj\"o, Swede
Recognition of the Russian threat in Poland. From othering to securitisation
The theory-driven research aims to investigate securitisation as a phenomenon applied to a particular case of Polish perception of Russia. Despite the fact that Russia’s expansionist ambitions toward neighbouring states have permanently given cause for concern, identifying an object as a potential threat to own national sovereignty requires a political will to proclaim it as such and to deal with it. We state that the traditional approach to security does not allow illustrating the whole mosaic of bilateral relations, one of the elements of which is national memory.
In the absence of any objective criteria for measuring and classifying threats, constructivists argue that threat is a subjective category. This study aims to identify the conditions behind securitisation of Russia, which shape the general public agreement over Polish defence policy. The work intends to test the assumption that public support for an increase in military spending depends on securitisation of Russia by political elites, the premise of which is the mobilisation of collective memory.
The author hopes to contribute to the existing literature on securitisation by addressing the question of threat construction through the role of external conditions and mobilisation of historical memory to facilitate the adoption of certain defence policy measures. Support for possible Polish engagement in military actions in accordance with the NATO principle of collective defence is observed against the background of the Russian-Ukrainian escalation in 2014. Although security concerns expressed in relation to Russian external policy prove to be largely independent of historical controversies, national memory reinforces the self-identification process, when shared memory is called upon to draw an unambiguous line between own community and Others
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