Zeldovich pancake

A Zeldovich pancake is a theoretical condensation of gas out of a primordial density fluctuation following the Big Bang. In 1970, Yakov B. Zeldovich showed that for an ellipsoid of gas on a supergalactic scale, an approximation can be used that will model the collapse as occurring most rapidly along the shortest axis, resulting in a pancake form.{{cite book

In 1989, Zeldovich and S. F. Shandarin showed that initial overlapping density fluctuations of random Gaussian fields would result in "dense pancakes, filaments, and compact clumps of matter".{{cite journal

At a higher level, the collapse of larger structures according to the Zeldovich approximation is known as second-generation pancakes or superpancakes. At still higher levels there is a transition to a hierarchical clustering model in which a hierarchy of collapsing structures exist. The Truncated Zeldovich Approximation allowed the method to be applied to these hierarchical, or bottom-up models of cosmological structure. This approach truncates the power law fluctuation spectrum at large values of k before applying the Zeldovich Approximation.{{cite journal

The first example of a Zeldovich pancake may have been identified in 1991 using the Very Large Array in New Mexico.{{cite news

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