A search for cosmological anisotropy using the Lyman alpha forest from
  SDSS quasar spectra
  The Cosmological Principle, the combined assumptions of cosmological isotropy
and homogeneity, underpins the standard model of Big Bang cosmology with which
we interpret astronomical observations. A new test of isotropy over the
redshift range $2<z<4$ and across large angular scales on the sky is presented.
We use the cosmological distribution of neutral hydrogen, as probed by the
Ly$\alpha$ forest seen towards distant quasars. The Sloan Digital Sky Survey
provides the largest dataset of quasar spectra available to date. We use
combined information from Data Releases 12 and 14 to select a sample of 142,661
quasars most suitable for this purpose. The scales covered by the data extend
beyond post-inflation causality scales, thus probing initial conditions in the
early universe. We identify significant spatially correlated systematic effects
that can emulate cosmological anisotropy. Once these systematics have been
accounted for, the data are found to be consistent with isotropy, providing an
important independent check on the standard model, consistent with results from
cosmic microwave background data.
