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In a milestone that will bear on future discoveries in nuclear and particle physics, today an international team including scientists from MIT announced that they have established a new upper limit on...
Simulations of damped Ly alpha and Lyman limit absorbers in different cosmologies: Implications for structure formation at high redshift
formation large scale structure of the Universe
2014/12/26
We use hydrodynamic cosmological simulations to study damped Lyα (DLA) and Lyman limit (LL) absorption at redshifts z = 2-4 in five variants of the cold dark matter scenario: COBE-normalized (CCDM), c...
Using data from the Two Micron All Sky Survey, we identify a population of infrared carbon stars with J-KS ≥ 2 in the Milky Way. These stars are shown to trace the stellar bar previously identified in...
Randall-Sundrum limit of f(R) brane-world models
Randall-Sundrum limit brane-world models
2011/10/17
By setting some special boundary conditions in the variational principle we obtain junction conditions for the five-dimensional $f(R)$ gravity which in the Einstein limit $f(R)\rightarrow R$ transform...
The fate of Cyg X-1: an empirical limit on BH-NS merger rate
Cyg X-1:empirical limit BH-NS merger rate
2011/10/12
The recent distance determination allowed precise estimation of the orbital parameters of Cyg X-1, which contains a massive 14.8 Msun BH with a 19.2 Msun O star companion. This system appears to be th...
Weak-field limit of Kaluza-Klein models with spherical compactification II: agreement with the observations
Weak-field limit Kaluza-Klein models spherical compactification agreement observations
2011/10/17
We investigate the classical gravitational tests for the Kaluza-Klein model with spherical (of a radius $a$) compactification of the internal space. The model contains also a bare cosmological constan...
Weak-field limit of Kaluza-Klein models with spherical compactification I: problematic aspects
Weak-field limit Kaluza-Klein models spherical compactification problematic aspects
2011/10/17
We investigate classical gravitational tests for the Kaluza-Klein model with spherical compactification of the internal two-dimensional space. In the case of the absence of a multidimensional bare cos...
A Lower Limit on the Halo Mass to form Supermassive Black Holes
black hole physics — hydrodynamics— galaxies: nuclei—accretion:accretion discs
2011/10/11
We consider a scenario where supermassive black holes form through direct accumulation of gas at the centre of proto-galaxies. In the first stage, the accumulated gas forms a super-massive star whose ...
A new limit on the Ultra-High-Energy Cosmic-Ray flux with the Westerbork Synthesis Radio Telescope
the Ultra-High-Energy Cosmic-Ray flux the Westerbork Synthesis Radio Telescope
2011/1/13
A particle cascade (shower) in a dielectric, for example as initiated by an ultra-high energy cosmic ray, will have an excess of electrons which will emit coherent \v{C}erenkov radiation, known as the...
Colour-magnitude diagrams, probabilistic synthesis models and the upper mass limit of the initial mass function
Cosmology and Extragalactic Astrophysics (astro-ph.CO)
2011/1/5
We present the underlying relations between colour-magnitude diagrams (CMDs) and synthesis models through the use of stellar luminosity distribution func- tions. CMDs studies make a direct use of the ...
Very Large Array observations of the 8 o'clock arc lens system: Radio emission and a limit on the star-formation rate
Cosmology and Extragalactic Astrophysics (astro-ph.CO)
2010/12/23
The 8 o'clock arc is a gravitationally lensed Lyman Break Galaxy (LBG) at redshift z=2.73 that has a star-formation rate (SFR) of 270 solar-mass/year (derived from optical and near-infrared spectrosco...
Quantum Cosmology Close to the Classical Big Bang Singularity and in the Semiclassical Limit
Quantum Cosmology Semiclassical Limit Big Bang Singularity
2010/3/18
We investigate a cosmological model whose energy content is described by a Chaplygin gas represented by a scalar field $\phi$ with an associated potential producing a big bang singularity such that fo...
A CCD Search for Wide Metal-Poor Binary Stars：Approaching the Metal-Depleted Substellar Limit
Wide Metal-Poor Binary Stars Metal-Depleted Substellar Limit
2009/6/18
A CCD Search for Wide Metal-Poor Binary Stars：Approaching the Metal-Depleted Substellar Limit。
The Mass/Eccentricity Limit in Double Star Astronomy
Stellar evolution statistics binaries
2009/5/19
A research that we conducted in 1963 on the evolution of
the binaries based on the available orbital data to obtain a philosophical
degree, led to the establishment of an interesting and new diagram...