Zeldovich einasto (1 Ergebnisse)
Giant voids in the Universe in Nature 300, 2 December 1982, pp. 407-413
Zeldovich [Zel'dovich], YA. B., Einasto, J. & S. F. Shandarin
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First edition in original wraps of an important work in the formation of our modern cosmological paradigm. Yakov Zeldovich's work was noted to be of import to the February 2016 announcement of the detection of gravitational waves - ripples in the fabric of spacetime - that were first predicted by Einstein's theory of general rel…ativity over 100 years ago. Russian scientists, specifically Zeldovich, contributed to the advances ("We Proved Einstein Right," RT, 12 February 2016; Graham, "Gravitational Waves Detected", Young Herald, 15 February 2016. Confirmation of Einstein's discovery is considered the most important scientific discovery in decades. For this 1982 paper, the authors began with a question: "Can we find observational evidence which can be used to discriminate between various theories of the formation of galaxies?" (Einasto, Yakov Zeldovich and the Cosmic Web Paradigm, IAU Symposium 308, 2015). As Einasto later wrote "if there exist some regularities in the large-scale distribution of galaxies, these regularities must reflect the conditions in the Universe during the formation of galaxies. Thus we had a leading idea to answer the Zeldovich question: We have to study the distribution of galaxies on large scales. We started to collect redshift data from all available sources. Since we needed data on large-scale distribution of galaxies, we collected redshifts not only for galaxies, but also from near cluster. as well as active galaxies" (ibid) The three then "used the redshift data they had collected "to plot galaxies on various â??slices' through the universe" and studied galaxy distribution based on cluster analysis (Gott, The Cosmic Web, 72). The authors and were able to depict these â??slices' as "two-dimensional cuts through the universe showed empty cells surrounded by walls. The slices were 487 million light-years by 487 million light-years and were 24 million light-years thick" (ibid). [The paper] brought together the work of the three scientists in an interesting way and "was quite a tour de force. Zeldovich brought the theory", known as the pancake theory (Gott, 72). The Zeldovich pancake is a theory of the formation of galaxies. The theory posits a condensation of gas emerging from "a primordial density fluctuation following the Big Bang" (Wikipedia). The paper includes a detailed discussion of the Zeldovich picture of pancakes making cells, filaments, forming where cell walls met, and clusters forming at the corners of the cells" (Gott). While Zeldovich â??brought the theory', "Einasto brought the observations", extending "the methods of studying matter distribution in galaxies using available photometric data about a galaxy as a whole as well as its basic individual stellar population. These he combined with spectroscopic measurements of the motions of the stars and gas inside the galaxy" (ibid; Ambartsumian International Prize). Einasto's methods were specific enough that the â??slices' the paper depicted showed the filaments Einasto had found. "Shandarin brought simulations" (ibid). In addition to N-body computer simulations based on the adiabatic picture, the test "used was the size of the largest connected structures based on a â??friends-of-friends' approach. Draw a sphere around each galaxy of a certain radius and link it to each â??friend' galaxy within that radius. As the radius for friendship is increased, the structures containing all friends of friends grow larger. The simulations showed the size of the friends-of-friends networks grew rapidly as the radius of the spheres linking them increased. Soon, the largest network spread all the way across the entire observational box. The observations followed exactly the same pattern. The high-density regions containing the galaxies looked connected across the entire universe. I always took this famous paper to be the archetypal one in favor of a cell structure for the universe, the picture that Zeldovich proposed" (ibid). Zeldovich also played a key r.
