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Cosmic Reionization On Computers. Properties of the Post-reionization IGM.

2016
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Release : 2016
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Book Synopsis Cosmic Reionization On Computers. Properties of the Post-reionization IGM. by :

Download or read book Cosmic Reionization On Computers. Properties of the Post-reionization IGM. written by . This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: We present a comparison between several observational tests of the post-reionization IGM and the numerical simulations of reionization completed under the Cosmic Reionization On Computers (CROC) project. We show that CROC simulations reproduce "out-of-the-box" the observed distributions of Gunn-Peterson optical depths, underscoring the importance of self-consistent modeling of radiative transfer. We also show that CROC simulations match well the observed distributions of dark gaps from SDSS quasars. Finally, we introduce a novel statistical probe of the small-scale structure in the IGM: heights and widths of transmission peaks. Simulations match the peak height distributions reasonably well, but do not reproduce the observed abundance of wide peaks.

Cosmic Reionization On Computers III. The Clumping Factor

2015
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Release : 2015
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Book Synopsis Cosmic Reionization On Computers III. The Clumping Factor by :

Download or read book Cosmic Reionization On Computers III. The Clumping Factor written by . This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: We use fully self-consistent numerical simulations of cosmic reionization, completed under the Cosmic Reionization On Computers project, to explore how well the recombinations in the ionized intergalactic medium (IGM) can be quantified by the effective "clumping factor." The density distribution in the simulations (and, presumably, in a real universe) is highly inhomogeneous and more-or-less smoothly varying in space. However, even in highly complex and dynamic environments, the concept of the IGM remains reasonably well-defined; the largest ambiguity comes from the unvirialized regions around galaxies that are over-ionized by the local enhancement in the radiation field ("proximity zones"). This ambiguity precludes computing the IGM clumping factor to better than about 20%. Furthermore, we discuss a "local clumping factor," defined over a particular spatial scale, and quantify its scatter on a given scale and its variation as a function of scale.

Cosmic Reionization On Computers

2016
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Release : 2016
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Book Synopsis Cosmic Reionization On Computers by :

Download or read book Cosmic Reionization On Computers written by . This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: In this paper I show that simulations of reionization performed under the Cosmic Reionization On Computers (CROC) project do converge in space and mass, albeit rather slowly. A fully converged solution (for a given star formation and feedback model) can be determined at a level of precision of about 20%, but such a solution is useless in practice, since achieving it in production-grade simulations would require a large set of runs at various mass and spatial resolutions, and computational resources for such an undertaking are not yet readily available. In order to make progress in the interim, I introduce a weak convergence correction factor in the star formation recipe, which allows one to approximate the fully converged solution with finite resolution simulations. The accuracy of weakly converged simulations approaches a comparable, ~20% level of precision for star formation histories of individual galactic halos and other galactic properties that are directly related to star formation rates, like stellar masses and metallicities. Yet other properties of model galaxies, for example, their HI masses, are recovered in the weakly converged runs only within a factor of two.

Cosmic Reionization on Computers. Ultraviolet Continuum Slopes and Dust Opacities in High Redshift Galaxies

2016
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Release : 2016
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Book Synopsis Cosmic Reionization on Computers. Ultraviolet Continuum Slopes and Dust Opacities in High Redshift Galaxies by :

Download or read book Cosmic Reionization on Computers. Ultraviolet Continuum Slopes and Dust Opacities in High Redshift Galaxies written by . This book was released on 2016. Available in PDF, EPUB and Kindle. Book excerpt: In this study, we compare the properties of stellar populations of model galaxies from the Cosmic Reionization On Computers (CROC) project with the exiting UV and IR data. Since CROC simulations do not follow cosmic dust directly, we adopt two variants of the dust-follows-metals ansatz to populate model galaxies with dust. Using the dust radiative transfer code Hyperion, we compute synthetic stellar spectra, UV continuum slopes, and IR fluxes for simulated galaxies. We find that the simulation results generally match observational measurements, but, perhaps, not in full detail. The differences seem to indicate that our adopted dust-follows-metals ansatzes are not fully sufficient. While the discrepancies with the exiting data are marginal, the future JWST data will be of much higher precision, rendering highly significant any tentative difference between theory and observations. It is, therefore, likely, that in order to fully utilize the precision of JWST observations, fully dynamical modeling of dust formation, evolution, and destruction may be required.

Cosmic Reionization On Computers II. Reionization History

2014
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Release : 2014
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Download or read book Cosmic Reionization On Computers II. Reionization History written by . This book was released on 2014. Available in PDF, EPUB and Kindle. Book excerpt:

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