Download or read book A Detailed Study of Star Formation at Its Cosmic Peak written by Cody James Lamarche and published by . This book was released on 2019 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The star-formation-rate density of the universe has decreased by a factor of ~ 10 over the last 10 billion years, indicating a major change in either the efficiency with with galaxies form their stars or the availability of star-forming gas over the same time. In this thesis, we study the stellar populations within galaxies during the epoch of peak cosmic star-formation, ~ 10 billion years ago, using infrared observations of the ionized, neutral, and molecular phases of the interstellar medium (ISM) therein. In particular, we focus on two galaxies within this era, both of which have vigorous star-formation as well as active galactic nuclei (AGN), in an effort to learn more about the modes of star-formation at early times as well as the influence of AGN feedback on star-formation. As a first example, we examine the stellar population within 3C 368, a Fanaroff-Riley Class II (FR-II) galaxy at redshift 1.131. Our observations suggest a powerful AGN, accompanied by vigorous and extended star formation. We estimate the age of the starburst and find that it is nearly concurrent with the latest episode of AGN flaring, suggesting a link between the growth of the supermassive black hole and stellar population in this source. Our ionized-gas observations suggest a low gas-phase metallicity within this source, consistent with the weak molecular gas lines that we observe. We suggest that perhaps 3C 368 is accreting pristine molecular gas from an external source, thereby diluting its gas-phase metallicity. For our second example, we investigate the star-formation within SDP.11, a gravitationally-lensed galaxy at redshift 1.783. Our high-resolution gas and dust-continuum observations show intense star-formation in this source extended over several kiloparsecs. Gravitational-lens modeling further indicates that the star formation in this source is extended over a 3-5 kpc rotating disk, suggesting that the starburst present here may not be the result of a major merger, as is the case for local ultraluminous infrared galaxies (ULIRGs), but some other mechanism. The findings presented in this thesis support the idea of a different mode of star-formation being present in high-redshift galaxies. In contrast to local ULIRGs, which have intense star-formation confined to their centers, we find kiloparsec-scale star-forming disks present in galaxies during the epoch of peak cosmic star-formation. While local star-forming galaxies tend to be the product of major-mergers, high-redshift starburst galaxies may well be the product of another process, perhaps accretion of material from the cosmic web.
Download or read book Star Formation Rates of Galaxies written by Andreas Zezas and published by Cambridge University Press. This book was released on 2021-04-29 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Star-formation is one of the key processes that shape the current state and evolution of galaxies. This volume provides a comprehensive presentation of the different methods used to measure the intensity of recent or on-going star-forming activity in galaxies, discussing their advantages and complications in detail. It includes a thorough overview of the theoretical underpinnings of star-formation rate indicators, including topics such as stellar evolution and stellar spectra, the stellar initial mass function, and the physical conditions in the interstellar medium. The authors bring together in one place detailed and comparative discussions of traditional and new star-formation rate indicators, star-formation rate measurements in different spatial scales, and comparisons of star-formation rate indicators probing different stellar populations, along with the corresponding theoretical background. This is a useful reference for students and researchers working in the field of extragalactic astrophysics and studying star-formation in local and higher-redshift galaxies.
Download or read book Star Formation Across Cosmic Time and Its Influence on Galactic Dynamics written by Jonathan Freundlich and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations show that ten billion years ago, galaxies formed their stars at rates up to twenty times higher than now. As stars are formed from cold molecular gas, a high star formation rate means a significant gas supply, and galaxies near the peak epoch of star formation are indeed much more gas-rich than nearby galaxies. Is the decline of the star formation rate mostly driven by the diminishing cold gas reservoir, or are the star formation processes also qualitatively different earlier in the history of the Universe? Ten billion years ago, young galaxies were clumpy and prone to violent gravitational instabilities, which may have contributed to their high star formation rate. Stars indeed form within giant, gravitationally-bound molecular clouds. But the earliest phases of star formation are still poorly understood. Some scenarii suggest the importance of interstellar filamentary structures as a first step towards core and star formation. How would their filamentary geometry affect pre-stellar cores? Feedback mechanisms related to stellar evolution also play an important role in regulating star formation, for example through powerful stellar winds and supernovae explosions which expel some of the gas and can even disturb the dark matter distribution in which each galaxy is assumed to be embedded. This PhD work focuses on three perspectives: (i) star formation near the peak epoch of star formation as seen from observations at sub-galactic scales; (ii) the formation of pre-stellar cores within the filamentary structures of the interstellar medium; and (iii) the effect of feedback processes resulting from star formation and evolution on the dark matter distribution.
Download or read book A Statistical and Multi wavelength Study of Star Formation in Galaxies written by Corentin Schreiber and published by Springer. This book was released on 2016-09-12 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a pioneering method for gleaning the maximum information from the deepest images of the far-infrared universe obtained with the Herschel satellite, reaching galaxies fainter by an order of magnitude than in previous studies. Using these high-quality measurements, the author first demonstrates that the vast majority of galaxy star formation did not take place in merger-driven starbursts over 90% of the history of the universe, which suggests that galaxy growth is instead dominated by a steady infall of matter. The author further demonstrates that massive galaxies suffer a gradual decline in their star formation activity, providing an alternative path for galaxies to stop star formation. One of the key unsolved questions in astrophysics is how galaxies acquired their mass in the course of cosmic time. In the standard theory, the merging of galaxies plays a major role in forming new stars. Then, old galaxies abruptly stop forming stars through an unknown process. Investigating this theory requires an unbiased measure of the star formation intensity of galaxies, which has been unavailable due to the dust obscuration of stellar light.
Download or read book Star Formation in Galaxies written by and published by . This book was released on 1987 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Worlds New Horizons in Astronomy and Astrophysics written by National Research Council and published by National Academies Press. This book was released on 2011-02-04 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Download or read book The Origin of Stars and Planetary Systems written by Charles J. Lada and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: A few years after the publication of The Physics of Star Formation and Early Stellar Evolution, we received a request from the publisher for an up dated second edition of this popular reference book. As originally intended, the volume had proved to be a useful "text" book for graduate astronomy courses and seminars which dealt with topics related to stellar origins. The book was based on a series of lectures delivered by a distinguished group of leading researchers at a NATO Advanced Study Institute (ASI) held in May 1990 on the island of Crete, Greece. The primary goal of the ASI was in fact to produce a book which "would simultaneously provide a broad and systematic overview of, as well as a rigorous introduction to, the fun damental physics and astronomy at the heart of modern research in star formation and early stellar evolution. " However, by 1995 concern had arisen among those who used the text as a reference for graduate seminars and courses that the book would need to be updated to stay abreast of the discoveries and progress in this rapidly evolving field. After some discussion we concluded that a new edition of the book was warranted and that the goal of producing a new edition would be best accomplished by organizing a second ASI in Crete to review the progress in star formation research.
Download or read book Evolution of Stars and Stellar Populations written by Maurizio Salaris and published by John Wiley & Sons. This book was released on 2005-12-13 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Evolution of Stars and Stellar Populations is a comprehensive presentation of the theory of stellar evolution and its application to the study of stellar populations in galaxies. Taking a unique approach to the subject, this self-contained text introduces first the theory of stellar evolution in a clear and accessible manner, with particular emphasis placed on explaining the evolution with time of observable stellar properties, such as luminosities and surface chemical abundances. This is followed by a detailed presentation and discussion of a broad range of related techniques, that are widely applied by researchers in the field to investigate the formation and evolution of galaxies. This book will be invaluable for undergraduates and graduate students in astronomy and astrophysics, and will also be of interest to researchers working in the field of Galactic, extragalactic astronomy and cosmology. comprehensive presentation of stellar evolution theory introduces the concept of stellar population and describes "stellar population synthesis" methods to study ages and star formation histories of star clusters and galaxies presents stellar evolution as a tool for investigating the evolution of galaxies and of the universe in general
Download or read book Star Formation Efficiency in Extended UV Disks and at High Redshift written by Isadora Chaves Bicalho and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perhaps one of the most enigmatic domains of astrophysics is that of galaxy formation and evolution.A galaxy is defined by its stellar and gas contents. Hence, any theory of galaxy formation has to address the question of the formation of stars.Observations show that star formation takes place in dense molecular clouds.Therefore, the efficiency of star formation of a galaxy is determined by its ability to form molecular clouds.The determination of these processes and their efficiency is among the most important issues in our understanding of star formation.The present work studies the star formation laws in a wide range of physical and dynamical conditions, even in low density environmentsand down to molecular cloud scales, as well as high redshift galaxies, to explore the cosmic star formation history.Low density environments, like the outermost disk of galaxies mimic the physical conditions of dwarf galaxies and also that of galaxiesin the early Universe. Across the Hubble time, there was a peak in the star formation rate, at z ~1-2, about ten billions years ago. Then the average star formation rate dropped by a factor 20 down to the present rate. This Ph.D focuses on the star formation efficiency in two contexts: in low environments, like outer galaxy disks and at the epoch the near the peak of star formation.
Download or read book Principles of Star Formation written by Peter Bodenheimer and published by Springer Science & Business Media. This book was released on 2011-07-10 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astrophysics as well as to active researchers in the field.
Download or read book The Formation of Stars written by Steven W. Stahler and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 865 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive treatment of star formation, one of the most active fields of modern astronomy. The reader is guided through the subject in a logically compelling manner. Starting from a general description of stars and interstellar clouds, the authors delineate the earliest phases of stellar evolution. They discuss formation activity not only in the Milky Way, but also in other galaxies, both now and in the remote past. Theory and observation are thoroughly integrated, with the aid of numerous figures and images. In summary, this volume is an invaluable resource, both as a text for physics and astronomy graduate students, and as a reference for professional scientists.
Download or read book Star Formation in Galaxy Evolution Connecting Numerical Models to Reality written by Nickolay Y. Gnedin and published by Springer. This book was released on 2015-09-09 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the elaborated and updated versions of the 24 lectures given at the 43rd Saas-Fee Advanced Course. Written by four eminent scientists in the field, the book reviews the physical processes related to star formation, starting from cosmological down to galactic scales. It presents a detailed description of the interstellar medium and its link with the star formation. And it describes the main numerical computational techniques designed to solve the equations governing self-gravitating fluids used for modelling of galactic and extra-galactic systems. This book provides a unique framework which is needed to develop and improve the simulation techniques designed for understanding the formation and evolution of galaxies. Presented in an accessible manner it contains the present day state of knowledge of the field. It serves as an entry point and key reference to students and researchers in astronomy, cosmology, and physics.
Download or read book The Physics of Star Formation and Early Stellar Evolution written by Charles J. Lada and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 779 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origin of stars is one of the principle mysteries of nature. During the last two decades advances in technology have enabled more progress to be made in the quest to understand stellar origins than at any other time in history. The study of star formation has developed into one of the most important branches of mod ern astrophysical research. A large body of observational data and a considerable literat ure now exist concerning this topic and a 1arge community of international astronomers and physicists devote their efforts attempting to decipher the secrets of stellar birth. Yet, the young astronomerjphysicist or more advanced researcher desiring to obtain a basic background in this area of research must sift through a very diverse and sometimes bewildering literature. A literature which includes research in many discip1ines and sub discip1ines of classical astrophysics from stel lar structure to the interstellar medium and encompasses the entire range of the electromagnetic spectrum from radio to gamma rays. Often, the reward of a suc cessfu1 foray through the current literature is the realization that the results can be obsolete and outdated as soon as the ink is dry in the journal or the conference proceeding in which they are published.
Download or read book Galaxies at High Redshift written by I. Pérez-Fournon and published by Cambridge University Press. This book was released on 2003-03-20 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents lectures of the XI Canary Islands Winter School of Astrophysics written by experts in the field.
Download or read book Structure Formation in the Universe written by Robert G. Crittenden and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a series of lectures given at the NATO Advanced Study Institute (ASI) "Structure Formation in the Universe", held at the Isaac Newton Institute in Cambridge in August, 1999. The ASI was held at a critical juncture in the development of physical cosmology, when a flood of new data concerning the large scale structure of the Universe was just be coming available. There was an air of excitement and anticipation: would the standard theories fit the data, or would new ideas and models be re quired? Cosmology has long been a field of common interest between East and West, with many seminal contributions made by scientists working in the former Soviet Union and Eastern bloc. A major aim of the ASI was to bring together scientists from across the world to discuss exciting recent developments and strengthen links. However, a few months before the meeting it appeared that it might have to be cancelled. The war in the former Yugoslavia escalated and NATO began a protracted bombing cam paign against targets in Kosovo and Serbia. Many scientists felt uneasy about participating in a NATO-funded meeting in this situation. After a great deal of discussion, it was agreed that the developing East West conflict only heightened the need for further communication and that the school should go ahead as planned, but with a special session devoted to discussion of the legitimacy of NATO's actions.
Download or read book Studying the Large Scale Structure and Interstellar Medium of Galaxies During the Epochs of Peak Cosmic Star Formation and Reionization with Infrared Fine Structure Lines written by Bade D. Uzgil and published by . This book was released on 2016 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infrared (IR) fine-structure (FS) lines from trace metals in the interstellar medium (ISM) of galaxies are valuable diagnostics of the physical conditions in a broad range of astrophysical environments, such gas irradiated by stellar far-ultraviolet (FUV) photons or X-rays from accreting supermassive black holes, called active galactic nuclei (AGN). The transparency of these lines to dust and their high escape fractions into the intergalactic medium (IGM) render them as useful probes to study the epochs of peak cosmic star formation (SF) and Reionization.
Download or read book The Properties and Evolution of Star Forming Regions Over Cosmic Time written by Maren Cosens and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Star formation is key to the regulation of galactic environments. Studying the sites of ongoing star formation is therefore critical to understanding the evolution of galaxies over cosmic time. Integral Field Spectrographs (IFS) have allowed astronomers to probe the dynamical processes of galaxies at high redshift, z∼1-3, revealing unique kiloparsec-scale "clumps" of star formation. The relationships between clump size, luminosity, and velocity dispersion are particularly important to understanding clump formation and evolution. These relationships have been measured in a variety of studies but disagreement remains about their nature and possible evolution with redshift. To investigate the cause of these differences, I collected a comprehensive sample of clump observations across redshifts and developed a Bayesian Markov Chain Monte Carlo fitting routine to robustly explore the scaling relationships of star-forming regions. There is evidence of a break into two clump populations based on their star formation rate surface density with differences in slope due to either the formation mode or geometry of the clump and host galaxy disk, but there is added uncertainty from limited observations at small clump sizes. To address this limitation, I observed a sample of compact H II regions in the local starburst galaxy, IC 10, with the Keck Cosmic Web Imager IFS at the W. M. Keck Observatory. I found these H II regions are offset to higher luminosity and velocity dispersion for a given size. These H II regions do not appear to be virialized, and instead show evidence that they are young and expanding. Even in the most compact H II regions, warm gas pressure from photoinization heating provides the dominant contribution to outward pressure and expansion. Improvements in instrumentation are also key to improving studies of the characteristics and evolution of star-forming regions, as well as many other astronomical objects. Liger, an adaptive optics fed IFS and imager for Keck Observatory, will provide improvements in resolution, field of view, and wavelength coverage compared to current instruments. I have developed the mechanical design of three major components of the Liger imager and sequential spectrograph: the filter wheel; selectable cold pupil stop; and mounting stage for the imager detector and IFS pick-off mirrors.
