THE LYMAN ALPHA FOREST IN THE SPECTRA OF QUASISTELLAR OBJECTS

摘要: Observations of redshifted Lyman alpha (Ly alpha) forest absorption in the spectra quasistellar objects (QSOs) provide a highly sensitive probe distribution gaseous matter universe. Over past two decades, optical spectroscopy with large ground-based telescopes, and more recently ultraviolet (UV) from space, have yielded wealth information on what appears to be gaseous, photoionized intergalactic medium (IGM), partly enriched by products stellar nucleosynthesis, residing coherent structures over many hundreds kiloparsecs. Recent progress cosmological hydro-simulations based or hierarchical structure formation models has led important insights into physical giving rise forest. If these ideas are correct, truly inter- protogalactic [at high redshift (z similar 3), main repository baryons] collapses under influence dark gravity flattened filamentary structures, which seen against background QSOs. With decreasing redshift, galaxies forming denser regions may contribute an increasing part Ly cross section. Comparisons between data samples new generation telescopes artificial simulations promise become useful tool.