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Author: Miguel A. Sánchez-Conde Publisher: MDPI ISBN: 3039360442 Category : Mathematics Languages : en Pages : 220
Book Description
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: Miguel A. Sánchez-Conde Publisher: MDPI ISBN: 3039360442 Category : Mathematics Languages : en Pages : 220
Book Description
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: Miguel A. Sánchez-Conde Publisher: ISBN: 9783039360451 Category : Astronomy Languages : en Pages : 220
Book Description
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: Leanne Delma Duffy Publisher: ISBN: Category : Dark matter (Astronomy) Languages : en Pages : 79
Book Description
ABSTRACT: The axion is one of the leading particle candidates for the universe's dark matter component. Despite possessing very small couplings, the axion's interaction with photons can be utilized to search for it using a microwave cavity detector. The Axion Dark Matter eXperiment (ADMX) uses such a detector to search for axions in our galactic halo. ADMX has recently added a new, high resolution channel to search for axions in discrete flows. ADMX's medium resolution channel searches for axions in the thermalized component of the halo. We review the motivation for the axion and its properties which make it a good dark matter candidate. We also review the arguments for the existence of discrete flows in galactic halos. A flow of discrete axions with small velocity dispersion will appear as a very narrow peak in the output of a microwave cavity detector. A high resolution search can detect such a peak with large signal to noise. We have performed such a search. The details of the high resolution axion search and analysis procedure are presented. In this search, no axion signal was found in the mass range 1.98-2.17 micro-eV. We place upper limits on the density of axions in local discrete flows based on this result.
Author: National Research Council Publisher: National Academies Press ISBN: 030917113X Category : Science Languages : en Pages : 222
Book Description
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.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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: Tomer Dov Yavetz Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Our method relies on a wave generalization of the classic Schwarzschild approach for constructing self-consistent halos -- such a halo consists of a suitable superposition of waves instead of particle orbits, chosen to yield a desired mean density profile. As an illustration, we apply the method to spherically symmetric halos. We derive an analytic relation between the particle distribution function and the wave superposition amplitudes, and show how it simplifies in the high energy (WKB) limit. We verify the stability of such constructed halos by numerically evolving the Schrodinger-Poisson system. The proposed algorithm provides an efficient and accurate way to simulate the time-dependent halo substructures from wave interference, and to test how they will affect dynamical tracers or other observables in a galaxy. The dissertation concludes with a brief discussion of the future prospects of these two methods, especially in the context of upcoming ground- and space-based missions like Rubin LSST and the Roman Space Telescope.
Author: Daniel Alejandro Gilman Publisher: ISBN: Category : Languages : en Pages : 257
Book Description
Dark matter makes up most of the mass in the Universe, and yet its particle nature remains unknown. Structure formation arguments provide a promising avenue to address this confounding mystery, as the mass and formation mechanism of the dark matter manifests in the abundance and density profiles of dark matter halos. Measurements of the halo mass function and the mass-concentration relation can therefore be cast as direct constraints on the particle nature of dark matter itself. Strong gravitational lensing by galaxies offers a unique probe of dark matter structure across cosmological distance, circumventing the use of luminous matter to trace the underlying dark matter. Observables from strong lens systems, particularly the image magnifications in quadruply-imaged quasars, probe the halo mass function directly on sub-galactic scales, below $10^8$ solar masses. In this low-mass regime, where halos become devoid of stars and gas, various dark matter models make unique predictions that lensing can constrain. In this dissertation, I present the development and implementation of a forward modeling framework that constrains any model based on dark matter theory, provided the model predicts the form of the halo mass function, and the density profile of individual halos. Using the framework I developed, my thesis presents an unprecedented constraint on the free-streaming length of dark matter that corresponds to a lower limit of $5.2 \rm{keV}$ on the mass of a thermal relic dark matter particle. In addition, I present the first constraint on the mass-concentration relation of Cold Dark Matter halos on sub-galactic scales across cosmological distance. The flexibility of the framework I developed broadens the scope of strong-lensing analyses to any structure formation model based on dark matter theory, underscoring the power of strong gravitational lensing as a probe of fundamental physics.
Author: Scott Dodelson Publisher: Academic Press ISBN: 0122191412 Category : Science Languages : en Pages : 462
Book Description
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: Miguel A. Sánchez-Conde
Author: Miguel A. Sánchez-Conde
Author: Mark Richard Lovell
Author: Miguel A. Sánchez-Conde
Author: Leanne Delma Duffy
Author: National Research Council
Author: Donnino Anderhalden
Author: 
Author: Tomer Dov Yavetz
Author: Daniel Alejandro Gilman
Author: Scott Dodelson