Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-08-17
Astronomy and Astrophysics
Astrophysics
13 pages, 11 figures, accepted by ApJ with minor revisions
Scientific paper
10.1086/524400
Radiative cooling by metals in shocked gas mediates the formation of ionization front instabilities in the galaxy today that are responsible for a variety of phenomena in the interstellar medium, from the morphologies of nebulae to triggered star formation in molecular clouds. An important question in early reionization and chemical enrichment of the intergalactic medium is whether such instabilities arose in the H II regions of the first stars and primeval galaxies, which were devoid of metals. We present three-dimensional numerical simulations that reveal both shadow and thin-shell instabilities readily formed in primordial gas. We find that the hard UV spectra of Population III stars broadened primordial ionization fronts, causing H2 formation capable of inciting violent thin- shell instabilities in D-type fronts, even in the presence of intense Lyman-Werner flux. The high post- front gas temperatures associated with He ionization sustained and exacerbated shadow instabilities, unaided by molecular hydrogen cooling. Our models indicate that metals eclipsed H2 cooling in I-front instabilities at modest concentrations, from 0.001- 0.01 solar. We conclude that ionization front instabilities were prominent in the H II regions of the first stars and galaxies, influencing the escape of ionizing radiation and metals into the early universe.
Norman Michael L.
Whalen Daniel
No associations
LandOfFree
Ionization Front Instabilities in Primordial H II Regions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Ionization Front Instabilities in Primordial H II Regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ionization Front Instabilities in Primordial H II Regions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-329296