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Author: Samantha W. Brunker Publisher: ISBN: Category : Dwarf galaxies Languages : en Pages : 0
Book Description
Green Pea galaxies are compact, extreme star-forming galaxies observed at intermediate redshifts (z = 0.15-0.4). Interest in the Green Pea galaxies has been steadily growing, especially once the Green Peas were discovered to exhibit escaping ionizing radiation. Green Pea galaxies have become prime analogs for studying the contributions of star-forming galaxies to reionization. Despite the intense interest in these unusual galaxies, there are several open questions regarding the nature of the Green Peas. This dissertation focuses on the KISSR Green Pea galaxies with the aim of addressing three outstanding questions regarding the Green Peas: (1) What is the range of characteristic properties of the Green Peas? (2) What triggered the starburst activity in the Green Peas? and (3) Why are the Green Peas low-metallicity systems? First, we confirm that the KISSR Green Pea galaxies are consistent with the properties of the original Green Pea galaxy sample. We show that the KISSR Green Peas are a factor of 17 times brighter than a typical star-forming galaxy of the same mass, which means 94% of the light is coming from the starburst population. Second, we designed and carried out a redshift survey using the Hydra multi-fiber positioner and Bench Spectrograph on the WIYN 3.5m telescope, which we used to investigate what impact a Green Pea's environment has on its star formation. We observed and measured redshifts for 1312 galaxies distributed between the 13 KISSR Green Pea fields. We used three density analysis techniques to quantify the galaxian densities around the KISSR Green Peas. Based on the combined results from these density analyses, we sorted the KISSR Green Peas into specific environment categories. We find that none of the KISSR Green Peas live in higher-density environments. A majority of them live in voids or in low-density environments tending towards isolation. We compare the measured densities for each Green Pea with several of their key physical properties. We find that there is no correlation between the galaxy properties and the galaxian densities, and we conclude that environment is not a strong factor in driving the star-formation activity in the KISSR Green Peas. Lastly, we present an analysis of the chemical compositions of the KISSR Green Peas. We successfully measured the weak [O III]A4363 emission line in 9 of the 13 KISSR Green Peas at a level that resulted in robust direct-method abundances. We confirm that the KISSR Green Peas are low-metallicity systems. We found that the Green Peas have slightly elevated N/O ratios, for which we propose a chemical evolution history that deviates from what is expected for "normal" star-forming galaxies. The multifaceted approach to studying Green Pea galaxies presented in this dissertation will provide a basis for a better understanding of the nature of Green Peas and how they fit into the larger narrative of galaxy formation and evolution.
Author: Samantha W. Brunker Publisher: ISBN: Category : Dwarf galaxies Languages : en Pages : 0
Book Description
Green Pea galaxies are compact, extreme star-forming galaxies observed at intermediate redshifts (z = 0.15-0.4). Interest in the Green Pea galaxies has been steadily growing, especially once the Green Peas were discovered to exhibit escaping ionizing radiation. Green Pea galaxies have become prime analogs for studying the contributions of star-forming galaxies to reionization. Despite the intense interest in these unusual galaxies, there are several open questions regarding the nature of the Green Peas. This dissertation focuses on the KISSR Green Pea galaxies with the aim of addressing three outstanding questions regarding the Green Peas: (1) What is the range of characteristic properties of the Green Peas? (2) What triggered the starburst activity in the Green Peas? and (3) Why are the Green Peas low-metallicity systems? First, we confirm that the KISSR Green Pea galaxies are consistent with the properties of the original Green Pea galaxy sample. We show that the KISSR Green Peas are a factor of 17 times brighter than a typical star-forming galaxy of the same mass, which means 94% of the light is coming from the starburst population. Second, we designed and carried out a redshift survey using the Hydra multi-fiber positioner and Bench Spectrograph on the WIYN 3.5m telescope, which we used to investigate what impact a Green Pea's environment has on its star formation. We observed and measured redshifts for 1312 galaxies distributed between the 13 KISSR Green Pea fields. We used three density analysis techniques to quantify the galaxian densities around the KISSR Green Peas. Based on the combined results from these density analyses, we sorted the KISSR Green Peas into specific environment categories. We find that none of the KISSR Green Peas live in higher-density environments. A majority of them live in voids or in low-density environments tending towards isolation. We compare the measured densities for each Green Pea with several of their key physical properties. We find that there is no correlation between the galaxy properties and the galaxian densities, and we conclude that environment is not a strong factor in driving the star-formation activity in the KISSR Green Peas. Lastly, we present an analysis of the chemical compositions of the KISSR Green Peas. We successfully measured the weak [O III]A4363 emission line in 9 of the 13 KISSR Green Peas at a level that resulted in robust direct-method abundances. We confirm that the KISSR Green Peas are low-metallicity systems. We found that the Green Peas have slightly elevated N/O ratios, for which we propose a chemical evolution history that deviates from what is expected for "normal" star-forming galaxies. The multifaceted approach to studying Green Pea galaxies presented in this dissertation will provide a basis for a better understanding of the nature of Green Peas and how they fit into the larger narrative of galaxy formation and evolution.
Author: Tianxing Jiang Publisher: ISBN: Category : Cosmic abundances Languages : en Pages : 106
Book Description
Green pea galaxies are a class of rare, compact starburst galaxies that have powerful optical emission line [OIII]$\lambda$5007. They are the best low-redshift analogs of high-redshift (z$>$2) Lyman-alpha emitting galaxies (LAEs). They provide unique opportunities to study physical conditions in high-redshift LAEs in great detail. In this dissertation, a few physical properties of green peas are investigated. The first study in the dissertation presents star formation rate (SFR) surface density, thermal pressure in HII regions, and a correlation between them for 17 green peas and 19 Lyman break analogs, which are nearby analogs of high-redshift Lyman break galaxies. This correlation is consistent with that found from the star-forming galaxies at z $\sim$ 2.5. In the second study, a new large sample of 835 green peas in the redshift range z = 0.011 -- 0.411 are assembled from Data Release 13 of the Sloan Digital Sky Survey (SDSS) with the equivalent width of the line [OIII]$\lambda$5007 $>$ 300\AA\ or the equivalent width of the line H$\beta$ $>$ 100\AA. The size of this new sample is ten times that of the original 80 star-forming green pea sample. With reliable T$_e$-based gas-phase metallicity measurements for the 835 green peas, a new empirical calibration of R23 (defined as ([OIII]$\lambda$$\lambda$4959,5007 + [OII]$\lambda$$\lambda$3726,3729)/H$\beta$) for strong line emitters is then derived. The double-value degeneracy of the metallicity is broken for galaxies with large ionization parameter (which manifests as log([OIII]$\lambda$$\lambda$4959,5007/[OII]$\lambda$$\lambda$3726,3729) $\geq$ 0.6). This calibration offers a good way to estimate metallicities for extreme emission-line galaxies and high-redshift LAEs. The third study presents stellar mass measurements and the stellar mass-metallicity relation of 828 green peas from the second study. The stellar mass covers 6 orders of magnitude in the range 10$^{5}$ -- 10$^{11}$ M$_{\odot}$, with a median value of 10$^{8.8}$ M$_{\odot}$. The stellar mass-metallicity relation of green peas is flatter and displays about 0.2 - 0.5 dex offset to lower metallicities in the range of stellar mass higher than 10$^{8}$ M$_{\odot}$ compared to the local SDSS star-forming galaxies. A significant dependence of the stellar mass-metallicity relation on star formation rate is not found in this work.
Author: Michael Nielsen Publisher: Princeton University Press ISBN: 0691202850 Category : Science Languages : en Pages : 272
Book Description
How the internet and powerful online tools are democratizing and accelerating scientific discovery Reinventing Discovery argues that we are living at the dawn of the most dramatic change in science in more than three hundred years. This change is being driven by powerful cognitive tools, enabled by the internet, which are greatly accelerating scientific discovery. There are many books about how the internet is changing business, the workplace, or government. But this is the first book about something much more fundamental: how the internet is transforming our collective intelligence and our understanding of the world. From the collaborative mathematicians of the Polymath Project to the amateur astronomers of Galaxy Zoo, Reinventing Discovery tells the exciting story of the unprecedented new era in networked science. It will interest anyone who wants to learn about how the online world is revolutionizing scientific discovery—and why the revolution is just beginning.
Author: Polychronis Papaderos Publisher: Springer Science & Business Media ISBN: 3642220185 Category : Science Languages : en Pages : 347
Book Description
Dwarf galaxy research constitutes an extremely vibrant field of astrophysical research, with many long-standing questions still unsettled and new ones constantly arising. The intriguing diversity of the dwarf galaxy population, observed with advanced ground-based and space-borne observatories over a wide spectral window providing an unprecedented level of detail, poses new challenges for both observers and theoreticians. The aim of this symposium was to bring together these two groups to exchange ideas and new results on the many evolutionary aspects of and open issues concerning dwarf galaxies. The main topics addressed include: the birth of dwarf galaxies: theoretical concepts and observable relics across wavelengths and time, the morphological, structural and chemical evolution of dwarf galaxies, possible evolutionary connections between early-type and late-type dwarfs, the star formation history of dwarf galaxies and its dependence on intrinsic and environmental properties, the origin and implications of starburst activity in dwarf galaxies, the fate of dwarfish systems born out of tidally ejected matter in galaxy collisions.
Author: Kieran Jay Edwards Publisher: Springer Science & Business Media ISBN: 3319065998 Category : Technology & Engineering Languages : en Pages : 112
Book Description
With the onset of massive cosmological data collection through media such as the Sloan Digital Sky Survey (SDSS), galaxy classification has been accomplished for the most part with the help of citizen science communities like Galaxy Zoo. Seeking the wisdom of the crowd for such Big Data processing has proved extremely beneficial. However, an analysis of one of the Galaxy Zoo morphological classification data sets has shown that a significant majority of all classified galaxies are labelled as “Uncertain”. This book reports on how to use data mining, more specifically clustering, to identify galaxies that the public has shown some degree of uncertainty for as to whether they belong to one morphology type or another. The book shows the importance of transitions between different data mining techniques in an insightful workflow. It demonstrates that Clustering enables to identify discriminating features in the analysed data sets, adopting a novel feature selection algorithms called Incremental Feature Selection (IFS). The book shows the use of state-of-the-art classification techniques, Random Forests and Support Vector Machines to validate the acquired results. It is concluded that a vast majority of these galaxies are, in fact, of spiral morphology with a small subset potentially consisting of stars, elliptical galaxies or galaxies of other morphological variants.
Author: Tyler Thrasher Publisher: Sasquatch Books ISBN: 1632174928 Category : Art Languages : en Pages : 293
Book Description
At the intersection of science, art, and design, this must-have coffee table book highlights 100 mind-blowing colors that you’ve likely never seen before. From Instagram sensation and self-described "mad scientist artist" Tyler Thrasher and creator of the popular Matter subscription box Terry Mudge, this book comes with a foreword by Hank Green. This gorgeous compendium contains 100 amazing colors that you might otherwise live your whole life unaware of. These colors exist in the strangest of places, and serve extremely specific functions in nature, or were human-made with one goal in mind. In this oversized, design-forward book you'll find entries for each of the 100 colors, organized in gradient order, with structural and impossible colors set at the end. Each entry has a 2-page spread with a full-page image of the color plus snappy descriptions, and easy-to-understand category symbols. Some entries include diagrams. Even includes structural colors and colors outside the range of human visibility! Also included is a brief introduction to color theory, a myth-busting section, plus index, glossary, and notes. Here is your universe in living color: Cosmic Latte: The average color of the universe. Dragon’s Blood: A tropical tree that bleeds red resin with incredible medicinal potential. Sonoluminescence: A color created by sound! Eigengrau: The color we perceive in the absence of light (and no, it's not "pitch black"). Perfect for anyone who loves science or art, and bursting with astonishing facts and stunning photography, The Universe in 100 Colors is a wonder for the senses.
Author: Nigel Shadbolt Publisher: Springer ISBN: 3030108899 Category : Computers Languages : en Pages : 260
Book Description
Social machines are a type of network connected by interactive digital devices made possible by the ubiquitous adoption of technologies such as the Internet, the smartphone, social media and the read/write World Wide Web, connecting people at scale to document situations, cooperate on tasks, exchange information, or even simply to play. Existing social processes may be scaled up, and new social processes enabled, to solve problems, augment reality, create new sources of value, and disrupt existing practice. This book considers what talents one would need to understand or build a social machine, describes the state of the art, and speculates on the future, from the perspective of the EPSRC project SOCIAM – The Theory and Practice of Social Machines. The aim is to develop a set of tools and techniques for investigating, constructing and facilitating social machines, to enable us to narrow down pragmatically what is becoming a wide space, by asking ‘when will it be valuable to use these methods on a sociotechnical system?’ The systems for which the use of these methods adds value are social machines in which there is rich person-to-person communication, and where a large proportion of the machine’s behaviour is constituted by human interaction.
Author: Samantha W. Brunker
Author: Samantha W. Brunker
Author: Tianxing Jiang
Author: Heather Rose Kurtz
Author: 
Author: Michael Nielsen
Author: Jean-René Roy
Author: Polychronis Papaderos
Author: Kieran Jay Edwards
Author: Tyler Thrasher
Author: Nigel Shadbolt