Download or read book Dwarf Galaxies as Probes of the Nature and Distribution of Dark Matter written by Anna Genina and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dark Matter in Dwarf Spheroidal Galaxies written by and published by . This book was released on 2014 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: From their unique location in orbit around the Milky Way, dwarf spheroidal galaxies are excellent laboratories for studying dark matter. In this thesis, information from the dynamics of stars in dwarf spheroidal galaxies is used to infer the mass distribution of dark matter in these objects. A more precise measurement of the mass distribution would give us valuable clues about the nature of dark matter and can help us to target dark matter searches. Classically, the mass of a dwarf galaxy is estimated from measurements of the stellar velocity dispersion profile which tells us the width of the stellar velocity distribution at different distances from the galactic centre. Unfortunately, the velocity dispersion profile only constrains the mass of the galaxy at one radius and places little constraint on dark matter models. To improve upon the classic analysis, one can complement information from the velocity dispersion measurements (the second moment of the velocity distribution) with information from higher moments which constrain the shape of the velocity distribution. We relax assumptions made in previous works and develop new methods that for the first time allow us to draw robust conclusions about the ability of higher moments to differentiate between dark matter models that are indistinguishable in the classic analysis. Whilst our methods are not able to verify predictions from cosmological simulations of dark matter, we found that the fourth moment of the velocity distribution can dramatically improve constraints on the mass distribution of dwarf galaxies and can be used to improve the precision of dark matter detection experiments.
Download or read book Connecting Quarks with the Cosmos written by National Research Council and published by National Academies Press. This book was released on 2003-03-12 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances made by physicists in understanding matter, space, and time and by astronomers in understanding the universe as a whole have closely intertwined the question being asked about the universe at its two extremesâ€"the very large and the very small. This report identifies 11 key questions that have a good chance to be answered in the next decade. It urges that a new research strategy be created that brings to bear the techniques of both astronomy and sub-atomic physics in a cross-disciplinary way to address these questions. The report presents seven recommendations to facilitate the necessary research and development coordination. These recommendations identify key priorities for future scientific projects critical for realizing these scientific opportunities.
Download or read book The Elephant in the Universe written by Govert Schilling and published by Harvard University Press. This book was released on 2022-01-01 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: An award-winning science journalist details the quest to isolate and understand dark matter--and shows how that search has helped us to understand the universe we inhabit. When you train a telescope on outer space, you can see luminous galaxies, nebulae, stars, and planets. But if you add all that together, it constitutes only 15 percent of the matter in the universe. Despite decades of research, the nature of the remaining 85 percent is unknown. We call it dark matter. In The Elephant in the Universe, Govert Schilling explores the fascinating history of the search for dark matter. Evidence for its existence comes from a wealth of astronomical observations. Theories and computer simulations of the evolution of the universe are also suggestive: they can be reconciled with astronomical measurements only if dark matter is a dominant component of nature. Physicists have devised huge, sensitive instruments to search for dark matter, which may be unlike anything else in the cosmos--some unknown elementary particle. Yet so far dark matter has escaped every experiment. Indeed, dark matter is so elusive that some scientists are beginning to suspect there might be something wrong with our theories about gravity or with the current paradigms of cosmology. Schilling interviews both believers and heretics and paints a colorful picture of the history and current status of dark matter research, with astronomers and physicists alike trying to make sense of theory and observation. Taking a holistic view of dark matter as a problem, an opportunity, and an example of science in action, The Elephant in the Universe is a vivid tale of scientists puzzling their way toward the true nature of the universe.
Download or read book Dark Matter in the Universe written by Marc S. Seigar and published by Morgan & Claypool Publishers. This book was released on 2015-10-12 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of dark matter, in both astrophysics and particle physics, has emerged as one of the most active and exciting topics of research in recent years. This book reviews the history behind the discovery of missing mass (or unseen mass) in the Universe, and ties this into the proposed extensions to the Standard Model of Particle Physics (such as Supersymmetry), which were being proposed within the same time frame. This book is written as an introduction to these problems at the forefront of astrophysics and particle physics, with the goal of conveying the physics of dark matter to beginning undergraduate majors in scientific fields. The book goes onto describe existing and upcoming experiments and techniques, which will be used to detect dark matter either directly on indirectly.
Download or read book Discovery Demographics and Dark Matter Implications of Faint Dwarf Galaxies in Wide area Optical Surveys written by Mitch Alexander McNanna and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combined sky coverage and depth of modern wide-area ground-based optical imaging surveys, in particular the Dark Energy Survey, have made possible the discovery and cataloging of the least luminous known galaxies. The demographics of faint dwarf galaxies throughout our local environment and the properties of the smallest individual ultra-faint galaxies have broad implications for astrophysics. I have designed and implemented search algorithms to identify faint dwarf galaxies both within the gravitational influence of the Milky Way and beyond out to the edges of the Local Group. The census of ultra-faint Milky Way satellites has placed competitive constraints on several alternative dark matter models, established the importance of the Large Magellanic Cloud in the formation of our local galactic environment, and increased our understanding of the connection between the smallest galaxies and the dark matter halos that host them. The search for faint field dwarf galaxies beyond the Milky Way uncovered one of the most diffuse dwarf galaxies ever discovered, the largest galaxy known at its luminosity. By comparing the current catalog of nearby dwarf galaxies to the results of searches over simulated versions of the Local Group, I conclude that we have likely exhausted the power of searches for resolved stellar populations in current wide-area sky coverage. Looking forward, this work informs what we might expect to discover in future surveys covering new areas of sky or with deeper data and how these discoveries will change our understanding of the particle properties of dark matter and the nature of galaxy formation.
Download or read book Progress in Dark Matter Research written by J. Val Blain and published by Nova Publishers. This book was released on 2005 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is generally believed that most of the matter in the universe is dark, i.e. cannot be detected from the light which it emits (or fails to emit). Its presence is inferred indirectly from the motions of astronomical objects, specifically stellar, galactic, and galaxy cluster/supercluster observations. It is also required in order to enable gravity to amplify the small fluctuations in the cosmic microwave background enough to form the large-scale structures that we see in the universe today. For each of the stellar, galactic, and galaxy cluster/supercluster observations the basic principle is that if we measure velocities in some region, then there has to be enough mass there for gravity to stop all the objects flying apart. Dark matter has important consequences for the evolution of the Universe and the structure within it. According to general relativity, the Universe must conform to one of three possible types: open, flat, or closed. The total amount of mass and energy in the universe determines which of the three possibilities applies to the Universe. In the case of an open Universe, the total mass and energy density (denoted by the Greek letter Omega) is less than unity. If the Universe is closed, Omega is greater than unity. For the case where Omega is exactly equal to one the Universe is "flat". This book details leading-edge research from around the globe.
Download or read book Dwarf Galaxies Keys to Galaxy Formation and Evolution written by Polychronis Papaderos and published by Springer Science & Business Media. This book was released on 2012-04-23 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Dark Matter in Late type Dwarf Galaxies written by Robert A. Swaters and published by . This book was released on 1999 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this thesis a study of the rotation curves and the dark matter properties of late-type dwarf galaxies is presented."--Abstract.
Download or read book Modern Cosmology written by Scott Dodelson and published by Academic Press. This book was released on 2003-03-13 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced text for senior undergraduates, graduate students and physical scientists in fields outside cosmology. This is a self-contained book focusing on the linear theory of the evolution of density perturbations in the universe, and the anisotropiesin the cosmic microwave background.
Download or read book In Search of Dark Matter written by Ken Freeman and published by Springer Science & Business Media. This book was released on 2006-08-25 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written for the educated non-scientist and scientist alike, it spans a variety of scientific disciplines, from observational astronomy to particle physics. Concepts that the reader will encounter along the way are at the cutting edge of scientific research. However the themes are explained in such a way that no prior understanding of science beyond a high school education is necessary.
Download or read book Dark Matter in the Universe written by John N. Bahcall and published by World Scientific. This book was released on 2004 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: If standard gravitational theory is correct, then most of the matterin the universe is in an unidentified form which does not emit enoughlight to have been detected by current instrumentation. This book isthe second editon of the lectures given at the 4th Jerusalem WinterSchool for Theoretical Physics, with new material added. The lecturesare devoted to the missing matter problem in the universe, thesearch to understand dark matter. The goal of this volume is to makecurrent research work on unseen matter accessible to students withoutprior experience in this area and to provide insights for experts inrelated research fields. Due to the pedagogical nature of the originallectures and the intense discussions between the lecturers and thestudents, the written lectures included in this volume often containtechniques and explanations not found in more formal journalpublications.
Download or read book Dark Sky Dark Matter written by J.M Overduin and published by CRC Press. This book was released on 2002-09-01 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Olbers' paradox states that given the Universe is unbounded, governed by the standard laws of physics, and populated by light sources, the night sky should be ablaze with light. Obviously this is not so. However, the paradox does not lie in nature but in our understanding of physics. A Universe with a finite age, such as follows from big-bang theor
Download or read book Faint Galaxies and Small Halos written by Ethan Oliver Nadler and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses the intersection of dark matter and galaxy formation physics by modeling the faintest galaxies in the Universe in a cosmological context. In the first part of this work, I present an empirical model for the connection between faint galaxies and small dark matter halos. Combining this model with tailored cosmological simulations of Milky Way analogs and state-of-the-art satellite galaxy observations yields new insights into dwarf galaxy formation and hierarchical structure formation. Next, I show that these same dwarf galaxy observations place stringent constraints on microphysical dark matter properties including its warmth, self-interactions, Standard Model interactions, minimum particle mass, and formation epoch. Finally, I describe a unified framework that combines dark matter constraints from dwarf galaxies and strong gravitational lensing, paving the way for next-generation surveys of small-scale cosmic structure to deliver unprecedented insights into dark matter physics.
Download or read book Star forming Dwarf Galaxies and Related Objects written by D. Kunth and published by Atlantica Séguier Frontières. This book was released on 1985 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stellar Streams as Probes of the Large scale Distribution of Matter Around Galaxies written by Anjali Doney Varghese and published by . This book was released on 2011 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: About 75% of the matter content of the Universe consists of a mysterious form, termed dark matter. The shapes of dark matter halos around galaxies hold important clues to the underlying nature of their constituent particles and have been an active area of research for several decades. Although, several techniques have been employed to find consistent estimates of the profiles of dark matter halos, it has proved to be a difficult task. In recent years, interesting stellar structures have been observed around galaxies. These structures are thought to be the remnants of galaxy mergers and have emerged as a useful tool to study dark halos at galactic scales. Prominent among these are thing, long features known aptly as stellar streams, or tidal streams as they are formed due to the tidal disruption of small satellite galaxies by the gravitational field of their large host galaxies. Since a tidal stream closely follows the orbit of its progenitor, it can be used as an effective tracer of the halo density profile. In this thesis, I extend previous modelling efforts with a significant improvement in methodology. The fitting routine used is based on Bayesian sampling. We examine how effectively the dark matter distribution of galaxies can be constrained, the quality and quantity of information needed to do so and specifically, whether it is at all possible to estimate the profiles of dark halos of external galaxies with only the projected coordinates of their stellar streams.
Download or read book Statistical Analysis of ALFALFA Galaxies written by Emmanouil Papastergis and published by . This book was released on 2013 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arecibo Legacy Fast ALFA (ALFALFA) survey is a blind, extragalactic survey in the 21cm emission line of atomic hydrogen (HI). Presently, sources have been cataloged over [ALMOST EQUAL TO]4 000 deg2 of sky (~60% of its final area), resulting in the largest HI-selected sample to date. We use the rich ALFALFA dataset to measure the statistical properties of HI-bearing galaxies, such as their mass distribution and clustering characteristics. These statistical distributions are determined by the properties of dark matter on galactic scales, and by the complex baryonic processes through which galaxies form over cosmic time. As a result, detailed studies of these distributions can lead to important insights in galaxy formation & evolution and near-field cosmology. In particular, we measure the space density of HI-bearing galaxies as a function of the width of their HI profile (i.e. the velocity width function of galaxies), and find substantial disagreement with the distribution expected in a lambda cold dark matter ([LAMDA]CDM) universe. In particular, the number of galaxies with maximum rotational velocities vrot [ALMOST EQUAL TO] 35 km s[-]1 (as judged by their HI velocity width) is about an order of magnitude lower than what predicted based on populating [LAMDA]CDM halos with modeled galaxies. We identify two possible solutions to the discrepancy: First, an alternative dark matter scenario in which the formation of low-mass halos is heavily suppressed (e.g. a warm dark matter universe with keV-scale dark matter particles). Secondly, we consider the possibility that rotational velocitites of dwarf galaxies derived from HI velocity widths may systematically underestimate the true mass of the host halo, due to the shape of their rotation curves. In this latter scenario, quantitative predictions for the internal kinematics of dwarf galaxies can be made, which can be checked in the future to probe the nature of dark matter. Furthermore, we take advantage of the overlap of ALFALFA with the Sloan Digital Sky Survey (SDSS), to measure the number density of galaxies as a function of their "baryonic" mass (stars + atomic gas). In the context of a [LAMDA]CDM cosmological model, the measured distribution reveals that low-mass halos are heavily "baryon depleted", i.e. their baryonic-to-dark mass ratio is much lower than the cosmological value. These baryon deficits are usually attributed to stellar feedback (e.g. supernova-driven gas outflows), but the efficiency implied by our measurement is extremely high. Whether such efficient feedback can be accommodated in a consistent picture of galaxy formation is an open question, and remains one of the principle scientific drivers for hydrodynamic simulations of galaxy formation. Lastly, we measure the clustering properties of HI-selected samples, through the two-point correlation function of ALFALFA galaxies. We find no compelling evidence for a dependence of clustering on HI mass, suggesting that the relationship between galactic gas mass and host halo mass is not tight. We furthermore find that HI galaxies cluster more weakly than optically selected ones, when no color selection is applied. However, SDSS galaxies with blue colors have very similar clustering characteristics with ALFALFA galaxies, both in real as well as in redshift space. On the other hand, HI galaxies cluster much more weakly than optical galaxies with red colors, and in fact "avoid" being located within [ALMOST EQUAL TO]3 Mpc from the latter. By considering the clustering properties of [LAMDA]CDM halos, we confirm our previous intuition for an MHI -Mh relation with large scatter, and find that spin parameter may be a key halo property related to the gas content of present-day galaxies.
