Download or read book The Globular Cluster Kinematics and Dark Matter Content of NGC 4649 written by Ainsley Campbell and published by . This book was released on 2011 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: The globular cluster system (GCS) of the elliptical galaxy NGC 4649 has been examined using the Gemini Multi-Object Spectrograph (GMOS); spectra for 156 candidate globular clusters (GCs) were obtained, extending to a galactocentric radius of 42 kpc. The system was found to have an even 78 GC candidates per population, using a colour of g-i = 0.92 (Faifer et al. 2011) to split the system into sub-populations. The populations refer to their metalicity; a g-i0.92 is considered metal-poor (MP), and a g-i0.92 is metal-rich (MR). Line-of-sight-velocity measurements and subsequent modelling, were used to measure the full GCS rotational velocity as 59+/-28 km/s, with a position angle of 218+/-28 degrees. The MR population was found to have rotational velocity of 81+/-42 km/s with a position angle of 221+/-29 degrees, while the MP population measures a rotational velocity of 30+/-36 km/s with a position angle of 202+/-73 degrees. The average velocity dispersion for the full GCS was calculated at 247+/-61 km/s, the MR population 266+/-94 km/s, and the MP population, 221+/-76 km/s. These findings are consistent (within uncertainties) with previous studies by Hwang et al.(2008), and Bridges et al. (2006). The velocity dispersion profile for all populations is constant with increasing radius, suggesting the presence of a dark matter (DM) halo. A tracer mass estimator was used to measure the mass at 42 kpc as (2.01+/-0.05)X10^{12} solar masses, for an isothermal potential, and (1.21+/-0.05)X10^{12} solar masses if the tracers followed the DM profile. Finally, it was estimated that M/L_{B}=22 - 44, consistent with the presence of considerable amounts of DM for a luminous galaxy.
Download or read book Globular Cluster Kinematics and Dark Matter Content of the Isolated Elliptical NGC 720 written by Amanda M. Schembri and published by . This book was released on 2011 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: We examine the globular cluster system (GCS) of the isolated elliptical NGC 720 using the Gemini Multi-Object Spectrograph (GMOS) and have obtained spectra for 241 candidate globular clusters (GCs) extending to a galactocentric radius of 40 kpc. Of the 241 candidates, 120 are confirmed GCs, where 46 are members of the metal-poor, blue, population and 74 are members of the metal-rich, red, population. A (g-i)=0.50 colour split is used to identify the blue and red populations. We measure the full GCS to have a rotational velocity (Vrot) of 50 +/- 7 km/s with a position angle (PA) of 170 +/- 69 degrees. The red population has a Vrot = 97 +/- 14 km/s with PA = 147 +\- 18 degrees and the blue population has a Vrot = 79 +/- 7 km/s with PA = 89 +/- 18 degrees. The full GCS has an average velocity dispersion of 168 +/- 22 km/s, for the red population is 156 +/- 30 km/s and for the blue population is 181 +/- 33 km/s. The velocity dispersion pro file for all populations is constant with increasing radius, suggesting the presence of a dark matter halo. Using a tracer mass estimator, we have measured the mass out to 40 kpc as 1.8(+0.6/-0.1)x10^12 Msun for a potential which traces the dark matter pro file. We also estimate the M/L_V = 30 - 70. This study extends our survey of GCSs to isolated environments.
Download or read book Globular Clusters Guides to Galaxies written by Tom Richtler and published by Springer Science & Business Media. This book was released on 2008-11-23 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal question of whether and how globular clusters can contribute to a better understanding of galaxy formation and evolution is perhaps the main driving force behind the overall endeavour of studying globular cluster systems. Naturally, this splits up into many individual problems. The objective of the Joint ESO-FONDAP Workshop on Globular Clusters - Guides to Galaxies was to bring together researchers, both observational and theoretical, to present and discuss the most recent results. Topics covered in these proceedings are: internal dynamics of globular clusters and interaction with host galaxies (tidal tails, evolution of cluster masses), accretion of globular clusters, detailed descriptions of nearby cluster systems, ultracompact dwarfs, formations of massive clusters in mergers and elsewhere, the ACS Virgo survey, galaxy formation and globular clusters, dynamics and kinematics of globular cluster systems and dark matter-related problems. With its wide coverage of the topic, this book constitutes a valuable reference of the scientific knowledge of the field.
Download or read book Learning in the Absence of Training Data written by Dalia Chakrabarty and published by Springer Nature. This book was released on 2023-07-13 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the concept of “bespoke learning”, a new mechanistic approach that makes it possible to generate values of an output variable at each designated value of an associated input variable. Here the output variable generally provides information about the system’s behaviour/structure, and the aim is to learn the input-output relationship, even though little to no information on the output is available, as in multiple real-world problems. Once the output values have been bespoke-learnt, the originally-absent training set of input-output pairs becomes available, so that (supervised) learning of the sought inter-variable relation is then possible. Three ways of undertaking such bespoke learning are offered: by tapping into system dynamics in generic dynamical systems, to learn the function that causes the system’s evolution; by comparing realisations of a random graph variable, given multivariate time series datasets of disparate temporal coverage; and by designing maximally information-availing likelihoods in static systems. These methodologies are applied to four different real-world problems: forecasting daily COVID-19 infection numbers; learning the gravitational mass density in a real galaxy; learning a sub-surface material density function; and predicting the risk of onset of a disease following bone marrow transplants. Primarily aimed at graduate and postgraduate students studying a field which includes facets of statistical learning, the book will also benefit experts working in a wide range of applications. The prerequisites are undergraduate level probability and stochastic processes, and preliminary ideas on Bayesian statistics.
Download or read book Dark Matter And Cosmic Web Story Second Edition written by Jaan Einasto and published by World Scientific. This book was released on 2024-04-29 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concepts of dark matter and the cosmic web are some of the most significant developments in cosmology in the past century. They have decisively changed the classical cosmological paradigm, which was first elaborated upon during the first half of the 20th century but ran into serious problems in the second half. Today, they are integral parts of modern cosmology, which explains everything from the Big Bang to inflation to the large-scale structure of the Universe.Dark Matter and Cosmic Web Story describes the contributions that led to a paradigm shift from the Eastern point of view. It describes the problems with the classical view, the attempts to solve them, the difficulties encountered by those solutions, and the conferences where the merits of the new concepts were debated. Amidst the science, the story of scientific work in a small country occupied by the Soviet Union and the tumultuous events that led to its breakup are detailed as well.The development of cosmology has often treated as a West-East conflict between the American school led by Jim Peebles in Princeton and the Soviet team led by Yakov Zeldovich in Moscow. Actually, the development of ideas was broader, and a certain role played the Tartu team. The Tartu cosmology school was founded by Ernst Öpik and has its own traditions and attitude to science. In the new edition of the book the interplay between three cosmology schools is written in more detail. The recent development of dark matter and cosmic web studies is described, as well as the evolution of global properties of the cosmic web.This book is accompanied by a website which contains additional material: copies of the originals of some crucial papers, astronomical movies, and movies which showcase the private life of the author. In this second edition, two chapters on the statistical description of the cosmic web and its development were added, as well as chapter on the sociology of science. To keep the length of this book reasonable, a lot of reorganisation of the text has been done as well.
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 Issues in Astronomy and Astrophysics 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 2981 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Astronomy and Astrophysics / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Astronomy and Astrophysics. The editors have built Issues in Astronomy and Astrophysics: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Astronomy and Astrophysics in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Astronomy and Astrophysics: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book The Distribution of Mass Within Spiral Galaxies written by Thomas Per Krister Martinsson and published by . This book was released on 2011 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Globular Cluster Systems written by Keith M. Ashman and published by Cambridge University Press. This book was released on 2008-12-11 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Globular clusters are roughly spherical, densely packed groups of stars found around galaxies. Most globular clusters probably formed at the same time as their host galaxies. Therefore they provide a unique fossil record of the conditions during the formation and early evolution of galaxies. This volume presents a comprehensive review of globular cluster systems. It summarizes their observed properties and shows how these constrain models of the structure of stars, the formation and evolution of galaxies and globular clusters, and the age of the Universe. For graduate students and researchers, this timely volume provides the definitive reference on globular cluster systems.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1991 with total page 838 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Most Interesting Galaxies in the Universe written by Joel L Schiff and published by Morgan & Claypool Publishers. This book was released on 2018-09-13 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prior to the 1920s it was generally thought, with a few exceptions, that our galaxy, the Milky Way, was the entire Universe. Based on the work of Henrietta Leavitt with Cepheid variables, astronomer Edwin Hubble was able to determine that the Andromeda Galaxy and others had to lie outside our own. Moreover, based on the work of Vesto Slipher, involving the redshifts of these galaxies, Hubble was able to determine that the Universe was not static, as had been previously thought, but expanding. The number of galaxies has also been expanding, with estimates varying from 100 billion to 2 trillion. While every galaxy in the Universe is interesting just by its very fact of being, the author has selected 51 of those that possess some unusual qualities that make them of some particular interest. These galaxies have complex evolutionary histories, with some having supermassive black holes at their core, others are powerful radio sources, a very few are relatively nearby and even visible to the naked eye, whereas the light from one recent discovery has been travelling for the past 13.4 billion years to show us its infancy, and from a time when the Universe was in its infancy. And in spite of the vastness of the Universe, some galaxies are colliding with others, embraced in a graceful gravitational dance. Indeed, as the Andromeda Galaxy is heading towards us, a similar fate awaits our Milky Way. When looking at a modern image of a galaxy, one is in awe at the shear wondrous nature of such a magnificent creation, with its boundless secrets that it is keeping from us, its endless possibilities for harboring alien civilizations, and we remain left with the ultimate knowledge that we are connected to its glory.
Download or read book The Dark Matter written by Wallace H. Tucker and published by William Morrow. This book was released on 1988 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fascinating and highly accessible treatment of the intriguing problem facing astronomers and cosmologists today: What is the universe made of, if only 50 percent of it can be accounted for by the luminous matter observable in galaxies?
Download or read book Wide Field Study of the Globular Cluster Systems in the Elliptical Galaxies NGC 4365 and NGC 4697 written by Mauricio Andrés Ortiz Alvarez and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Globular Cluster dark Matter Halo Connection written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structure and Dynamics of Globular Clusters written by S. G. Djorgovski and published by . This book was released on 1993 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Formation and Evolution of Star Clusters written by Kenneth Janes and published by . This book was released on 1991 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics and Evolution of Active Galactic Nuclei written by Hagai Netzer and published by Cambridge University Press. This book was released on 2013-09-16 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive introduction to the theory underpinning our study of active galactic nuclei and the ways we observe them.
