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Author : John David Capriotti
Publisher :
ISBN 13 :
Total Pages : 130 pages
Book Rating : 4.:/5 (319 download)
Download or read book Dark Matter Halos and Tidal Effects in Parabolic Galaxy Encounters written by John David Capriotti and published by . This book was released on 1998 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Robyn Ellyn Sanderson
Publisher :
ISBN 13 :
Total Pages : 188 pages
Book Rating : 4.:/5 (774 download)
Download or read book Understanding Dark Matter Halos with Tidal Caustics written by Robyn Ellyn Sanderson and published by . This book was released on 2011 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The products of interactions between galaxies with a high mass ratio and low orbital angular momentum are studied. The interactions scatter the material from the smaller galaxy into structures with distinctive dynamics and morphology, including high local densities and a simple density profile related to properties of the participating galaxies. The role of the larger galaxy's tides in creating these structures and their relation to a well-studied class of mathematical objects motivates us to name them "tidal caustics". We study the densities achievable in tidal caustics for a typical merger of this type using an example from the Andromeda galaxy to determine whether they are sufficient to produce a detectable gamma-ray signal from self-interactions in the dark matter component, for likely particle models of dark matter. We find that the expected signal is an order of magnitude too low to be detected with current instruments. We also study the constraints that can be placed on the properties of the participating galaxies by observing the surface brightness profiles of the tidal caustics. We find that the local gravity and gravity gradient of the larger galaxy, and the energy spread and initial phase space density of the smaller galaxy, can be jointly constrained by fitting this profile. The constraints are degenerate but model-independent. We find that measurements of multiple caustics and the velocity of the material in each caustic along the line of sight give information about the orbital angular momentum and the deviations from spherical symmetry in the larger galaxy, though this information is somewhat model-dependent. We discuss the main technical difficulty in fitting the surface brightness profile: determining the inclination angle of the caustic. We demonstrate that a simple model can successfully recover the necessary parameters for some cases, and that a simple modification to this model will improve its success rate.
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 : Philip L. Arras
Publisher :
ISBN 13 :
Total Pages : 584 pages
Book Rating : 4.E/5 ( download)
Download or read book An Environmental Impact Study written by Philip L. Arras and published by . This book was released on 2000 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 726 pages
Book Rating : 4.F/5 ( download)
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1998 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 4 pages
Book Rating : 4.:/5 (873 download)
Download or read book The First Dark Microhalos written by and published by . This book was released on 2005 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Earth-mass dark matter halos are likely to have been the first bound structures to form in the Universe. Whether such objects have survived to the present day in galaxies depends on, among other factors, the rate of encounters with normal stars. In this letter, we estimate the amount of tidal heating and mass loss in microhalos as a result of stellar encounters. We find that while microhalos are only mildly heated in dwarf galaxies of low stellar density, and they should have been completely destroyed in bulge or M32-like regions of high stellar density. In disk galaxies, such as the Milky Way, the disruption rate depends strongly on the orbital parameters of the microhalo; while stochastic radial orbits in triaxial Galactic potential are destroyed first, systems on non-planar retrograde orbits with large pericenters survive the longest. Since many microhalos lose a significant fraction of their material to unbound tidal streams, the final dark matter distribution in the solar neighborhood is better described as a superposition of microstreams rather than as a set of discrete spherical clumps in an otherwise homogeneous medium. Different morphologies of microhalos have implications for direct and indirect dark matter detection experiments.
Author : Massimo Persic
Publisher :
ISBN 13 :
Total Pages : 632 pages
Book Rating : 4.3/5 (91 download)
Download or read book Dark and Visible Matter in Galaxies written by Massimo Persic and published by . This book was released on 1997 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Matthew William Craig
Publisher :
ISBN 13 :
Total Pages : 314 pages
Book Rating : 4.:/5 (34 download)
Download or read book At the Heart of Darkness written by Matthew William Craig and published by . This book was released on 1997 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : P Murdin
Publisher : CRC Press
ISBN 13 : 1000523039
Total Pages : 5610 pages
Book Rating : 4.0/5 (5 download)
Download or read book Encyclopedia of Astronomy & Astrophysics written by P Murdin and published by CRC Press. This book was released on 2001-01-01 with total page 5610 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a unique collaboration, Nature Publishing Group and Institute of Physics Publishing have published the most extensive and comprehensive reference work in astronomy and astrophysics. This unique resource covers the entire field of astronomy and astrophysics and this online version includes the full text of over 2,750 articles, plus sophisticated search and retrieval functionality and links to the primary literature. The Encyclopaedia's authority is assured by editorial and advisory boards drawn from the world's foremost astronomers and astrophysicists. This first class resource is an essential source of information for undergraduates, graduate students, researchers and seasoned professionals, as well as for committed amateurs, librarians and lay people wishing to consult the definitive astronomy and astrophysics reference work.
Author : M. Wilkinson
Publisher :
ISBN 13 :
Total Pages : 154 pages
Book Rating : 4.:/5 (799 download)
Download or read book The Dark Matter Halos of Galaxies written by M. Wilkinson and published by . This book was released on 1999 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jun-Hwan Choi
Publisher : ProQuest
ISBN 13 : 9780549330585
Total Pages : 226 pages
Book Rating : 4.3/5 (35 download)
Download or read book The Dynamics of Satellite and Dark Matter Halo Interactions on Galaxy Formation and Evolution written by Jun-Hwan Choi and published by ProQuest. This book was released on 2007 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Houjun Mo
Publisher : Cambridge University Press
ISBN 13 : 0521857937
Total Pages : 841 pages
Book Rating : 4.5/5 (218 download)
Download or read book Galaxy Formation and Evolution written by Houjun Mo and published by Cambridge University Press. This book was released on 2010-05-20 with total page 841 pages. Available in PDF, EPUB and Kindle. Book excerpt: A coherent introduction for researchers in astronomy, particle physics, and cosmology on the formation and evolution of galaxies.
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:
Author : Jean-Rene Gauthier
Publisher :
ISBN 13 : 9781124868011
Total Pages : 122 pages
Book Rating : 4.8/5 (68 download)
Download or read book A Comprehensive Study of the Cool Gas Content of Massive Dark Matter Halos written by Jean-Rene Gauthier and published by . This book was released on 2011 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is based on the results of an on-going investigation of the cool, T & sim; 104 K, gas present in massive dark matter halos traced by luminous red galaxies (LRGs) at z & sim; 0.5. It consists of three parts. The first part (Chapter 2) presents a series of measurements of the large-scale clustering of MgII lambdalambda 2796,2803 absorbers with respect to a population of LRGs. From the cross-correlation measurements between the absorbers and the galaxies, the mean bias of the dark matter halos in which the absorbers reside is derived. One finds a 1-sigma anti-correlation between mean halo bias and absorber strength W r(2796) that translates into a 1-sigma anti-correlation between mean galaxy mass and Wr(2796). The results indicate that a significant fraction of the MgII absorber population of W r(2796) = 1-1.5A are found in group-size dark matter halos of log Mh 13.4, whereas absorbers of Wr(2796) 1.5A are primarily seen in halos of log Mh 12.7. In the second part of this thesis, a series of constraints on the covering fraction of cool gas are derived in Chapter 3. The results of an on-going spectroscopic follow-up of close LRG-Mg II absorber pairs are presented in Chapter 4. This spectroscopic sample consists of 70 photometrically selected LRGs at physical projected separations rho & sim; 400 kpc/h from a QSO sightline. The moderate-resolution spectra confirm a physical association between the cool gas revealed by the presence of MgII absorption features and the LRG halo in 15 cases. From a pair sample with no prior knowledge of the presence/absence of MgII absorbers, a covering fraction kappa = 0.13+0.05-0.06 is found for Wr(2796) 0.3A and rho
Author : Karia Radh Dibert
Publisher :
ISBN 13 :
Total Pages : 40 pages
Book Rating : 4.:/5 (18 download)
Download or read book The Effects of Inelastic Self-interacting Dark Matter on Galactic Halo Properties V written by Karia Radh Dibert and published by . This book was released on 2018 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Self-interacting dark matter, which serves as an alternative to collisionless cold dark matter, may be useful for solving the small-scale galaxy formation problems present in the Lambda-Cold Dark Matter model. So far, most self-interacting dark matter simulations have considered only elastic collisions between particles. Using the results of a numerical implementation in the AREPO code, the effects of two-state inelastic dark matter on the density profiles, velocity dispersions, pseudo-phase-space density profiles, orbital anisotropy parameter profiles, and principal axis ratios of galactic halos are examined. We find that inelastic self-interacting dark matter halos differ from both cold dark matter halos and elastic self-interacting dark matter halos in density profiles, in velocity dispersion profiles, in pseudo-phase-space density profiles, and in orbital anisotropy parameter profiles, while the shapes of the halos generated by elastic and inelastic self-interacting dark matter models are relatively similar.
Author : Gerard Lemson
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (61 download)
Download or read book Environmental Influences on Dark Matter Halos and Consequences for the Galaxies Within Them written by Gerard Lemson and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Martina Kleinheinrich
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (17 download)
Download or read book Dark Matter Halos of Galaxies Studied with Weak Gravitational Lensing written by Martina Kleinheinrich and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
