Quasars and the Intergalactic Medium at Cosmic Dawn

Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization

The H atoms inside minihalos (i.e. halos with virial temperatures Tvir ≤ 10 K, in the mass range roughly from 10M⊙ to 10 8 M⊙) during the cosmic dark ages in a ΛCDM universe produce a redshifted background of collisionally-pumped 21-cm line radiation which can be seen in emission relative to the cosmic microwave background (CMB). Previously, we used semi-analytical calculations of the 21-cm sig...

Intergalactic Medium

The 21 Centimeter Background from the Cosmic Dark Ages: Minihalos and the Intergalactic Medium before Reionization

The H atoms inside minihalos (i.e. halos with virial temperatures Tvir ≤ 10K, in the mass range roughly from 10M⊙ to 10 M⊙) during the cosmic dark ages in a ΛCDM universe produce a redshifted background of collisionally-pumped 21-cm line radiation which can be seen in emission relative to the cosmic microwave background (CMB). Previously, we used semi-analytical calculations of the 21-cm signal...

Optical Depth of the Cosmic Microwave Background and Reionization of the Intergalactic Medium

We examine the constraints on the epoch of reionization (redshift zr) set by recent WMAP-3 observations of τe = 0.09 ± 0.03, the electron-scattering optical depth of the cosmic microwave background (CMB), combined with models of highredshift galaxy and black hole formation. Standard interpretation begins with the computed optical depth, τe = 0.042± 0.003, for a fully ionized medium out to zr = ...

Simulations of the Intergalactic Medium

I present a review by epoch of baryons in the intergalac-tic medium (IGM), from the first star until today. Recent observations indicate a protracted period of reionization, suggesting multiple populations of reionizers; detection of these z ∼ > 6 sources is a key goal that is now coming within reach. The optical Lyman alpha forest (2 ∼ < z ∼ < 4) is well-described by the Fluctuating Gunn-Peter...