pic] Meiksin's research has concentrated largely on aspects of extra-galactic astronomy and cosmology. His principal interests are the structure of the Intergalactic Medium (the baryons left over from the Big Bang that didn't make galaxies) and the Large-Scale Structure of the Universe. He is also a Participant of the Sloan Digital Sky Survey , and maintains a keen interest in the science that may be achieved with LOFAR and an envisioned Square Kilometre Array .

Meiksin coordinates the Edinburgh Centre for Computational Astrophysics.

The Intergalactic Medium

Observations of intervening absorption lines in quasar spectra at redshifts up to z = 6 provide invaluable insight into the primordial density fluctuation spectrum and the chemical composition of some of the earliest formed cosmological structures, as well as of the UV background that ionizes them. Both the Lyman-α forest and the metal absorption systems are sensitive probes of the epochs of galaxy formation, reionization, reheating, and the chemical enrichment of the universe. Meiksin and his collaborators have used numerical simulations of the formation of structure in the IGM to study the properties of the Lyman-α forest predicted in Cold Dark Matter dominated cosmologies. The simulations show that the structures giving rise to the Lyman-α forest span a wide range in morphologies, from sponge-like to sheet-like to filamentary to spheroidal. Virtually all the baryons in the Universe are found to be contained in these structures at high redshifts.

For more publications and to learn more about my research on the Lyman-α forest, click here for the IGM web pages at the Edinburgh Centre for Computational Astrophysics.


21-cm Tomography

Measurements of the spectral and spatial structures of the 21-cm line emission and absorption from HI at high redshifts may provide a means of probing the epoch of heating of the IGM at 5 < z < 10 and its nature. With his collaborators, Meiksin has shown how, through a combination of preheating and radiation, an early generation of sources could excite 21-cm radiation from a warm HI component of the IGM prior to its complete reionization. The resulting patchwork of 21-cm emission could serve as a valuable tool for understanding the epoch, nature, and sources of the reionization of the universe, as well as the morphology of the IGM at early times. The patchwork may be detectable using the Low Frequency Radio Array ( LOFAR ) in the Netherlands, or by a Square Kilometre Array ( SKA ).

To learn more about LOFAR , click here

To learn more about the Square Kilometre Array, click here


The Large-Scale Structure of the Universe

Our understanding of the formation of galaxies and their clustering has developed enormously in the past 2 decades. The picture that has evolved is that structures arise from the gravitational instability of initially small density perturbations in an otherwise homogeneous expanding universe. The Cold Dark Matter model has been the most successful in predicting the observed properties and clustering patterns of galaxies. An essential tool in establishing the connection between the initial density perturbations and the clustering pattern of galaxies measured today is the power spectrum of the density fluctuations. Meiksin and his collaborators have shown that gravitational growth will induce correlations in the power spectrum between different modes, which must be accounted for in making any statistical comparison between the clustering of the galaxies and model predictions. They have also shown that current large redshift surveys like the 2dF and the Sloan Digital Sky Survey may be able to detect a component in the power spectrum due to acoustic oscillations of the baryons at the time of matter-radiation decoupling in the early universe.

For publications and to learn more about the Sloan Digital Sky Survey, click here