منابع مشابه
ASTRONOMY AND ASTROPHYSICS The entropy history of the universe.
ASTRONOMY AND ASTROPHYSICS The entropy history of the universe. Abstract. Although usual hierarchical clustering scenarios agree with the main observed properties of Lyman-α clouds and galaxies, they seem to fail to reproduce the cluster temperature-X-ray luminosity relation. A possible explanation is that the IGM is reheated by supernovae or quasars before cluster formation. In this article, u...
متن کاملExploring the Universe: Space-Based Astronomy and Astrophysics
For millennia until the Second World War, astronomical observations were limited to visible light, the type of electromagnetic radiation sensed by the human eye. When people look at the sky with the naked eye, they see only stars and patches of dark against dense star backgrounds, as in the southern Milky Way. With a telescope, one can see nebulae, or clouds of gas, shining either by fluorescen...
متن کاملUnsmoothing valuation-based indices using multiple regimes
Valuation error and valuation index smoothing have been the subject of a great deal of recent research efforts, largely due to concerns over the quality of investment decisions that can be made using valuation-based data. To date, unsmoothing models have assumed that the variances in valuation noise and market noise are at a constant ratio, producing a constant unsmoothing parameter. This paper...
متن کاملPrimordial Nucleosynthesis with CMB Inputs: Probing the Early Universe and Light Element Astrophysics
Cosmic microwave background (CMB) determinations of the baryon-to-photon ratio η ∝ Ωbaryonh 2 will remove the last free parameter from (standard) big bang nucleosynthesis (BBN) calculations. This will make BBN a much sharper probe of early universe physics, for example, greatly refining the BBN measurement of the effective number of light neutrino species, Nν,eff . We show how the CMB can impro...
متن کاملASTROPHYSICS The NASA Astrophysics Data System : Overview
The NASA Astrophysics Data System Abstract Service has become a key component of astronomical research. It provides bibliographic information daily, or near daily, to a majority of astronomical researchers worldwide. We describe the history of the development of the system and its current status. Urania (Boyce 1996), and the ADS role in the emerging electronic astronomical data environment are ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Nature
سال: 1985
ISSN: 0028-0836,1476-4687
DOI: 10.1038/313634a0