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Author :
Release : 2012
Genre :
Kind : eBook
Book Rating : 480/5 ( reviews)
Book Synopsis Simulations of Cosmic Reionization by :
Download or read book Simulations of Cosmic Reionization written by . This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Milan Raicevic
Release : 2010
Genre : Radiative transfer
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Book Synopsis Simulations of Cosmic Reionization by : Milan Raicevic
Download or read book Simulations of Cosmic Reionization written by Milan Raicevic. This book was released on 2010. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we investigate numerically how ionizing photons emitted by stars in galaxies cause the reionization of the Universe, the transition during which most of the gas in the Universe from a mostly neutral, to a highly ionised state it is in today. To this end, we discuss and improve two techniques for the transport of ionising radiation across cosmological volumes, analyse the sources of ionising photons at high redshifts predicted by a semi-analytical galaxy formation model (GALFORM), and combine these to make consistent model of how reionization proceeds. Our improvements to the hybrid characteristics (HC) radiative transport scheme are significant, making the code faster and more accurate, as demonstrated by our contribution to a code comparison paper (Iliev et al., 2009). Our improvements to the SimpleX radiative transport scheme allow for accurate and significantly better numerically converged calculations of the speeds of ionization fronts of cosmological HII regions. This is accomplished by a much more thorough analysis of how to properly model the density?eld on the unstructured density?eld in SimpleX. The dependence of the ionizing emissivity of GALFORM galaxies on various parameters of the model is examined. We show that massive stars formed in abundance because of the assumed top-heavy stellar initial mass function during starbursts in the Baugh et al. (2005) model, triggered by galaxy mergers, are the dominant source of ionizing photons. We show that the luminosity functions predicted by this model are in good agreement with the most recent Hubble Space Telescope results at z \gtrsim 8. The model also demonstrates that most photons are produced in faint galaxies which are not yet seen in the current data. We then combine the sources predicted by GALFORM with the SimpleX RT scheme to model inhomogeneous reionization including the effects of source suppression. We investigate how the morphology of reionization depends on the model for the sources, which may be crucial for future observations of this cosmic epoch.
Author : Andrei Mesinger
Release : 2019-12-23
Genre : SCIENCE
Kind : eBook
Book Rating : 348/5 ( reviews)
Book Synopsis The Cosmic 21-cm Revolution by : Andrei Mesinger
Download or read book The Cosmic 21-cm Revolution written by Andrei Mesinger. This book was released on 2019-12-23. Available in PDF, EPUB and Kindle. Book excerpt: The redshifted 21-cm signal is set to transform astrophysical cosmology, bringing a historically data-starved field into the era of Big Data. Corresponding to the spin-flip transition of neutral hydrogen, the 21-cm line is sensitive to the temperature and ionization state of the cosmic gas, as well as to cosmological parameters. Crucially, with the development of new interferometers it will allow us to map out the first billion years of our Universe, enabling us to learn about the properties of the unseen first generations of galaxies. Rapid progress is being made on both the observational and theoretical fronts, and important decisions on techniques and future direction are being made. The Cosmic 21-cm Revolution gathers contributions from current leaders in this fast-moving field, providing both an overview for graduate students and a reference point for current researchers.
Author : Andrei Mesinger
Release : 2015-11-28
Genre : Science
Kind : eBook
Book Rating : 57X/5 ( reviews)
Book Synopsis Understanding the Epoch of Cosmic Reionization by : Andrei Mesinger
Download or read book Understanding the Epoch of Cosmic Reionization written by Andrei Mesinger. This book was released on 2015-11-28. Available in PDF, EPUB and Kindle. Book excerpt: The dawn of the first stars, galaxies and black holes signaled a fundamental milestone in our Universe’s evolution: the Epoch of Reionization. The light from these galactic ancestors began spreading out, ionizing virtually every atom in existence. Our Universe transitioned from darkness to light, from cold to hot, from simple and boring to the wondrous cosmic zoo we see around us today. Despite its importance, observations of reionization have been few, and their interpretation has been highly controversial. Fortunately, this is rapidly changing. We will soon enter the "Big Data” era of this mysterious epoch, driven by an upcoming wave of observations with state-of-the-art telescopes as well as new sophisticated analysis tools. The aim of this volume is to summarize the current status and future outlook of the reionization field. We bring together leading experts in many sub-disciplines, highlighting the measurements that will illuminate our understanding of reionization and the cosmic dawn: (i) 21cm interferometry; (ii) high-redshift quasar spectra; (iii) high-redshift galaxy surveys; (iv) primary and secondary anisotropies of the Cosmic Microwave Background; (v) high-resolution studies of the metal content of early galaxies. We seek a roadmap to interpreting the wealth of upcoming observations. What is the best use of limited observational resources? How do we develop theoretical tools tailored for each observation? Ultimately, what will we learn about the epoch of reionization and our galactic ancestors?
Author :
Release : 2014
Genre :
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Book Synopsis Cosmic Reionization On Computers I. Design and Calibration of Simulations by :
Download or read book Cosmic Reionization On Computers I. Design and Calibration of Simulations written by . This book was released on 2014. Available in PDF, EPUB and Kindle. Book excerpt:
