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Author : Wayne Ngan
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)
Download or read book Dynamical Signatures of Dark Matter Substructures on Tidal Streams written by Wayne Ngan and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure and Substructure of Cold Dark Matter Halos written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the structure and substructure of Lambda-CDM halos using a suite of high-resolution cosmological N-body simulations. Our analysis of the substructure population of dark matter halos focuses on their mass and peak circular velocity functions, as well as their spatial distribution and dynamics. In our analysis, we consider the whole population of subhalos physically associated with the main halo, defined as those that have, at some time, crossed within the virial radius of the main progenitor. We find that this population extends beyond 3 times the virial radius and includes objects on unorthodox orbits, several of which travel at velocities approaching the nominal escape speed from the system. We trace the origin of these unorthodox orbits to the tidal dissociation of bound groups, which results in the ejection of some systems along tidal streams. This process primarily influences low-mass systems leading to clear mass-dependent biases in their spatial distribution and kinematics: the lower the subhalo mass at accretion time the more concentrated and kinematically hotter their descendant population. When quantified in terms of present day subhalo mass these trends disappear, presumably due to the increased effect of dynamical friction and tidal stripping on massive systems. We confirm several of these results using the ultra-high resolution Aquarius simulations, which extend the dynamic range of the subhalo mass function by nearly 3 orders of magnitude. Using these simulations we confirm that the substructure mass function follows a power-law, $dN/dM\propto M^{-1.9}$, and exhibits very little halo-to-halo scatter. This implies that the total mass in substructure within a given halo is bounded to a small fraction of the total halo mass, with the smooth component dominating the halo inner regions. Using the Aquarius simulations we study the structure of galaxy-sized Lambda-CDM halos. We find that the spherically averaged density profiles become increasingly sh.
Author : Miguel A. Sánchez-Conde
Publisher : MDPI
ISBN 13 : 3039360442
Total Pages : 220 pages
Book Rating : 4.0/5 (393 download)
Download or read book The Role of Halo Substructure in Gamma-Ray Dark Matter Searches written by Miguel A. Sánchez-Conde and published by MDPI. This book was released on 2020-05-28 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important, open research topic today is to understand the relevance that dark matter halo substructure may have for dark matter searches. In the standard cosmological model, halo substructure or subhalos are predicted to be largely abundant inside larger halos, for example, galaxies such as ours, and are thought to form first and later merge to form larger structures. Dwarf satellite galaxies—the most massive exponents of halo substructure in our own galaxy—are already known to be excellent targets for dark matter searches, and indeed, they are constantly scrutinized by current gamma-ray experiments in the search for dark matter signals. Lighter subhalos not massive enough to have a visible counterpart of stars and gas may be good targets as well, given their typical abundances and distances. In addition, the clumpy distribution of subhalos residing in larger halos may boost the dark matter signals considerably. In an era in which gamma-ray experiments possess, for the first time, the exciting potential to put to test the preferred dark matter particle theories, a profound knowledge of dark matter astrophysical targets and scenarios is mandatory should we aim for accurate predictions of dark matter-induced fluxes for investing significant telescope observing time on selected targets and for deriving robust conclusions from our dark matter search efforts. In this regard, a precise characterization of the statistical and structural properties of subhalos becomes critical. In this Special Issue, we aim to summarize where we stand today on our knowledge of the different aspects of the dark matter halo substructure; to identify what are the remaining big questions, and how we could address these; and, by doing so, to find new avenues for research.
Author : Heidi Jo Newberg
Publisher : Springer
ISBN 13 : 3319193368
Total Pages : 256 pages
Book Rating : 4.3/5 (191 download)
Download or read book Tidal Streams in the Local Group and Beyond written by Heidi Jo Newberg and published by Springer. This book was released on 2015-12-29 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is written by leading scientists in the field, who review the current state of our knowledge of tidal streams in the Milky Way, the Andromeda galaxy, and in other nearby galaxies. The cosmological origins of dwarf galaxies and the physical processes by which they are tidally disrupted into streams and incorporated into galaxy halos are discussed. The techniques that have been used to identify tidal streams are presented and will be useful to researchers who would like to find substructures in the next generation of optical sky surveys, including Pan-STARRS and LSST. The methods that are currently under development to constrain both large scale distribution of dark matter in the Milky Way and the (small scale) lumpiness of the dark matter distribution are also explained. The authors also provide motivation for future spectroscopic surveys of Milky Way halo stars, which will aid both in the identification of tidal streams and the constraint of dark matter properties. This volume is aimed at graduate students who are beginning this field of research, but is also a resource for researchers who study tidal streams and related fields. In addition to presenting the physical processes by which tidal streams are created, it also reviews the current state of the observations and the progress towards utilizing these observations to constrain the distribution of dark matter in the Milky Way. The book will introduce anyone with a background in astrophysics to the field of tidal streams.
Author :
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.:/5 (893 download)
Download or read book Cold Dark Matter Substructure and Galactic Disks I written by and published by . This book was released on 2007 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: We conduct a series of high-resolution, fully self-consistent dissipation less N-body simulations to investigate the cumulative effect of substructure mergers onto thin disk galaxies in the context of the [Lambda]CDM paradigm of structure formation. Our simulation campaign is based on a hybrid approach combining cosmological simulations and controlled numerical experiments. Substructure mass functions, orbital distributions, internal structures, and accretion times are culled directly from cosmological simulations of galaxy-sized cold dark matter (CDM) halos. We demonstrate that accretions of massive subhalos onto the central regions of host halos, where the galactic disk resides, since z ≈ 1 should be common occurrences. In contrast, extremely few satellites in present-day CDM halos are likely to have a significant impact on the disk structure. This is due to the fact that massive subhalos with small orbital pericenters that are most capable of strongly perturbing the disk become either tidally disrupted or suffer substantial mass loss prior to z = 0. One host halo merger history is subsequently used to seed controlled N-body experiments of repeated satellite impacts on an initially-thin Milky Way-type disk galaxy. These simulations track the effects of six dark matter substructures, with initial masses in the range ≈ (0.7-2) x 101° M{sub {circle_dot}} (≈ 20-60% of the disk mass), crossing the disk in the past ≈ 8 Gyr. We show that these accretion events produce several distinctive observational signatures in the stellar disk including: a long-lived, low-surface brightness, ring-like feature in the outskirts; a significant flare; a central bar; and faint filamentary structures that (spuriously) resemble tidal streams in configuration space. The final distribution of disk stars exhibits a complex vertical structure that is well-described by a standard 'thin-thick' disk decomposition, where the 'thick' disk component has emerged primarily as a result of the interaction with the most massive subhalo. We conclude that satellite-disk encounters of the kind expected in [Lambda]CDM models can induce morphological features in galactic disks that are similar to those being discovered in the Milky Way, M31, and in other nearby and distant disk galaxies. These results highlight the significant role of CDM substructure in setting the structure of disk galaxies and driving galaxy evolution. Upcoming galactic structure surveys and astrometric satellites may be able to distinguish between competing cosmological models by testing whether the detailed structure of galactic disks is as excited as predicted by the CDM paradigm.
Author : Francisco Prada
Publisher :
ISBN 13 :
Total Pages : 408 pages
Book Rating : 4.3/5 (91 download)
Download or read book Satellites and Tidal Streams written by Francisco Prada and published by . This book was released on 2004 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Edvige Corbelli
Publisher : Springer Science & Business Media
ISBN 13 : 1402034075
Total Pages : 551 pages
Book Rating : 4.4/5 (2 download)
Download or read book The Initial Mass Function 50 Years Later written by Edvige Corbelli and published by Springer Science & Business Media. This book was released on 2007-10-06 with total page 551 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theideatocelebrate50yearsoftheSalpeterIMFoccurredduringtherecent IAU General Assembly in Sydney, Australia. Indeed, it was from Australia that in July 1954 Ed Salpeter submitted his famous paper "The Luminosity Function and Stellar Evolution" with the rst derivation of the empirical stellar IMF. This contribution was to become one of the most famous astrophysics papers of the last 50 years. Here, Ed Salpeter introduced the terms "original mass function" and "original luminosity function", and estimated the pro- bility for the creation of stars of given mass at a particular time, now known as the "Salpeter Initial Mass Function", or IMF. The paper was written at the Australian National University in Canberra on leave of absence from Cornell University (USA) and was published in 1955 as 7 page note in the Astroph- ical Journal Vol. 121, page 161. To celabrate the 50th anniversary of the IMF, along with Ed Salpeter’s 80th birthday, we have organized a special meeting that brought together scientists involved in the empirical determination of this fundamental quantity in a va- ety of astrophysical contexts and other scientists fascinated by the deep imp- cations of the IMF on star formation theories, on the physical conditions of the gas before and after star formation, and on galactic evolution and cosmology. The meeting took place in one of the most beautiful spots of the Tuscan countryside, far from the noise and haste of everyday life.
Author : Farbod Kamiab
Publisher :
ISBN 13 :
Total Pages : 85 pages
Book Rating : 4.:/5 (827 download)
Download or read book Satellite Dynamics in Dark Matter Halos written by Farbod Kamiab and published by . This book was released on 2010 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: I have used an analytic model of tidal interactions to predict the evolution of a substructure in a static dark matter halo. Given the initial conditions of the satellite and background halo, the model predicts with high accuracy the mass loss of the satellite and also its density evolution. The main phenomena taken into account in the model are tidal truncation at the tidal radius of the satellite and heating due to tidal shocks at the pericenter of its orbit.
Author : E. J. Alfaro
Publisher : Cambridge University Press
ISBN 13 : 9780521481779
Total Pages : 384 pages
Book Rating : 4.4/5 (817 download)
Download or read book The Formation of the Milky Way written by E. J. Alfaro and published by Cambridge University Press. This book was released on 1995-08-03 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review examines all the key physical processes involved in the formation and evolution of the Milky Way, based on an international meeting held in Granada (Spain).
Author : International Astronomical Union. Symposium
Publisher : Cambridge University Press
ISBN 13 : 9780521863483
Total Pages : 524 pages
Book Rating : 4.8/5 (634 download)
Download or read book Binary Stars as Critical Tools and Tests in Contemporary Astrophysics (IAU S240) written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2007-08-27 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU S240 focuses on recent advances across the broad field of binary star research.
Author : Peter G. Jonker
Publisher : Springer
ISBN 13 : 9789402421453
Total Pages : 589 pages
Book Rating : 4.4/5 (214 download)
Download or read book The Tidal Disruption of Stars by Massive Black Holes written by Peter G. Jonker and published by Springer. This book was released on 2021-11-19 with total page 589 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume provides an overview of the fast-developing field of tidal disruption events. For several decades, astronomers speculated that a hapless star could wander too close to a massive black hole and be torn apart by tidal forces. Yet it is only with the recent advent of wide-field transient surveys that such events have been detected. Written by a team of prominent researchers, the chapters detail the discoveries made so far in this burgeoning field of study across the entire electromagnetic spectrum, from gamma-rays through X-rays, ultra-violet, optical, infrared, and radio. In addition, they show how tidal disruption events can be used to study the properties of otherwise undetectable supermassive black holes; the populations and dynamics of stars in galactic nuclei; the physics of black hole accretion, including the potential to detect relativistic effects near a SMBH; and the physics of (radio) jet formation and evolution in a pristine environment. Finally, the book outlines important outstanding questions about TDEs. With more than 100 color images, the volume will be useful to researchers and others interested in learning more about this promising area of astrophysics. Previously published in Space Science Reviews in the Topical Collection “The Tidal Disruption of Stars by Massive Black Holes”
Author : International Astronomical Union. Colloquium
Publisher : Cambridge University Press
ISBN 13 : 9780521852043
Total Pages : 456 pages
Book Rating : 4.8/5 (52 download)
Download or read book Near-Field Cosmology with Dwarf Elliptical Galaxies (IAU C198) written by International Astronomical Union. Colloquium and published by Cambridge University Press. This book was released on 2005 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of IAUC 198, covering important issues related to near-field cosmology with dwarf elliptical galaxies.
Author : Scott Dodelson
Publisher : Academic Press
ISBN 13 : 0122191412
Total Pages : 462 pages
Book Rating : 4.1/5 (221 download)
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.
Author : Ignacio Ferreras
Publisher : UCL Press
ISBN 13 : 1911307614
Total Pages : 200 pages
Book Rating : 4.9/5 (113 download)
Download or read book Fundamentals of Galaxy Dynamics, Formation and Evolution written by Ignacio Ferreras and published by UCL Press. This book was released on 2019-04-02 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxies, along with their underlying dark matter halos, constitute the building blocks of structure in the Universe. Of all fundamental forces, gravity is the dominant one that drives the evolution of structures from small density seeds at early times to the galaxies we see today. The interactions among myriads of stars, or dark matter particles, in a gravitating structure produce a system with fascinating connotations to thermodynamics, with some analogies and some fundamental differences. Ignacio Ferreras presents a concise introduction to extragalactic astrophysics, with emphasis on stellar dynamics, and the growth of density fluctuations in an expanding Universe. Additional chapters are devoted to smaller systems (stellar clusters) and larger ones (galaxy clusters). Fundamentals of Galaxy Dynamics, Formation and Evolution is written for advanced undergraduates and beginning postgraduate students, providing a useful tool to get up to speed in a starting research career. Some of the derivations for the most important results are presented in detail to enable students appreciate the beauty of maths as a tool to understand the workings of galaxies. Each chapter includes a set of problems to help the student advance with the material.
Author : Michael Travis Busha
Publisher :
ISBN 13 :
Total Pages : 378 pages
Book Rating : 4.3/5 (91 download)
Download or read book The Equilibrium Structure of Dark Matter Halos written by Michael Travis Busha and published by . This book was released on 2007 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : International Astronomical Union. Symposium
Publisher : Astronomical Society of the Pacific
ISBN 13 :
Total Pages : 560 pages
Book Rating : 4.3/5 (91 download)
Download or read book Dark Matter in Galaxies written by International Astronomical Union. Symposium and published by Astronomical Society of the Pacific. This book was released on 2004 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : International Astronomical Union. Colloquium
Publisher : Cambridge University Press
ISBN 13 : 9780521849081
Total Pages : 586 pages
Book Rating : 4.8/5 (49 download)
Download or read book Outskirts of Galaxy Clusters (IAU C195) written by International Astronomical Union. Colloquium and published by Cambridge University Press. This book was released on 2004-12-16 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the International Astronomical Union Colloquium no. 195, held in Torino, Italy in 2004. The meeting investigated the formation of galaxies within a full cosmological context, focusing on the outer regions of galaxy clusters. The observed correlation of optical and radio properties of galaxies with their environment indicates that the formation and evolution of galaxies is intimately linked to the formation of large scale structure. With chapters written by leading authorities in the field, this timely volume investigates the role of the environment in determining the properties of galaxies. It describes the distribution of matter and galaxies on the largest scales in the Universe, the processes of cluster and galaxy formation, their role and interplay. This is a valuable collection of review articles for professional astronomers.
