At the earliest epochs of structure formation in cold dark matter (CDM) cosmologies, the smallest nonlinear objects are the numerous small halos that condense with virial temperatures below ∼ 104 K. Such "minihalos" are not yet resolved in large-scale three-dimensional cosmological simulations. Here we employ a semianalytic method, combined with three-dimensional simulations of individual minihalos, to examine their importance during cosmological reionization. We show that, depending on when reioni-zation takes place, they potentially play an important role as sinks of ionizing radiation. If reionization occurs at sufficiently high redshifts (zr ≳ 20), the intergalactic medium is heated to ∼ 104 K and most minihalos never form. On the other hand, if zr ≲ 20, a significant fraction (≳ 10%) of all baryons have already collapsed into minihalos, and are subsequently removed from the halos by photoevaporation as the ionizing background flux builds up. We show that this process can require a significant budget of ionizing photons, exceeding the production by straightforward extrapolations back in time of known quasar and galaxy populations by a factor of up to ∼ 10 and ∼ 3, respectively.

Haiman, Z., Abel, T., Madau, P. (2001). Photon consumption in minihalos during cosmological reionization. THE ASTROPHYSICAL JOURNAL, 551(2), 599-607 [10.1086/320232].

Photon consumption in minihalos during cosmological reionization

Madau, P
2001

Abstract

At the earliest epochs of structure formation in cold dark matter (CDM) cosmologies, the smallest nonlinear objects are the numerous small halos that condense with virial temperatures below ∼ 104 K. Such "minihalos" are not yet resolved in large-scale three-dimensional cosmological simulations. Here we employ a semianalytic method, combined with three-dimensional simulations of individual minihalos, to examine their importance during cosmological reionization. We show that, depending on when reioni-zation takes place, they potentially play an important role as sinks of ionizing radiation. If reionization occurs at sufficiently high redshifts (zr ≳ 20), the intergalactic medium is heated to ∼ 104 K and most minihalos never form. On the other hand, if zr ≲ 20, a significant fraction (≳ 10%) of all baryons have already collapsed into minihalos, and are subsequently removed from the halos by photoevaporation as the ionizing background flux builds up. We show that this process can require a significant budget of ionizing photons, exceeding the production by straightforward extrapolations back in time of known quasar and galaxy populations by a factor of up to ∼ 10 and ∼ 3, respectively.
Articolo in rivista - Articolo scientifico
Cosmology: Theory; Early universe; Galaxies: evolution; Galaxies: formation;
English
2001
551
2
599
607
none
Haiman, Z., Abel, T., Madau, P. (2001). Photon consumption in minihalos during cosmological reionization. THE ASTROPHYSICAL JOURNAL, 551(2), 599-607 [10.1086/320232].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/453349
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