Download or read book Probing Model independent Modified Gravity and Axion Dark Matter written by Sankarshana Srinivasan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modified Gravity Progresses And Outlook Of Theories Numerical Techniques And Observational Tests written by Baojiu Li and published by World Scientific. This book was released on 2019-10-10 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modified gravity theories have been a main focus of theoretical cosmology research in the past decade or so, and have been quickly developing into a mature research field that attracts attention, interest and effort from both theoretical and observational cosmologists. To be prepared for fully exploiting the future observational data, and to provide a guidance for people who are new to this field, it is useful to have a comprehensive review to summarise the current state of knowledge and to foresee the future developments.This book presents expert reviews on different topics in the field, which are then coordinated and organised in a self-consistent and self-contained manner. It is suitable for graduate students and researchers interested in the frontier research of gravity theories.
Download or read book Probing Cosmic Dark Matter and Dark Energy with Weak Gravitational Lensing Statistics written by Masato Shirasaki and published by Springer. This book was released on 2015-11-18 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book the applicability and the utility of two statistical approaches for understanding dark energy and dark matter with gravitational lensing measurement are introduced. For cosmological constraints on the nature of dark energy, morphological statistics called Minkowski functionals (MFs) to extract the non-Gaussian information of gravitational lensing are studied. Measuring lensing MFs from the Canada–France–Hawaii Telescope Lensing survey (CFHTLenS), the author clearly shows that MFs can be powerful statistics beyond the conventional approach with the two-point correlation function. Combined with the two-point correlation function, MFs can constrain the equation of state of dark energy with a precision level of approximately 3–4 % in upcoming surveys with sky coverage of 20,000 square degrees. On the topic of dark matter, the author studied the cross-correlation of gravitational lensing and the extragalactic gamma-ray background (EGB). Dark matter annihilation is among the potential contributors to the EGB. The cross-correlation is a powerful probe of signatures of dark matter annihilation, because both cosmic shear and gamma-ray emission originate directly from the same dark matter distribution in the universe. The first measurement of the cross-correlation using a real data set obtained from CFHTLenS and the Fermi Large Area Telescope was performed. Comparing the result with theoretical predictions, an independent constraint was placed on dark matter annihilation. Future lensing surveys will be useful to constrain on the canonical value of annihilation cross section for a wide range of mass of dark matter annihilation. Future lensing surveys will be useful to constrain on the canonical value of annihilation cross section for a wide range of mass of dark matter.
Download or read book Non standard Models of Dark Matter and Their Experimental Signatures written by Marat Freytsis and published by . This book was released on 2012 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The weakly interacting massive particle (WIMP) paradigm gives an elegant mechanism for the generation of dark matter densities with the appropriate properties to be consistent with current observations. While in its minimal implementation, the only opportunity to test the reality of the scenario is by directly detecting the WIMP itself, cosmic ray anomalies observed several years ago imply the possibility of an extended dark matter sector in which secondary annihilations or decays can occur before interacting with the standard model. This opens up the possibility of detecting other parts of dark sector in a much wider set of experiments than those typically considered in connection to dark matter. In this dissertation I study several alternative models, capable of yielding signals across a broad range of experimental approaches. I study the prospects for detecting a light boson X with mass mX ≤ 100 MeV at a low energy electron-proton collider. Focus is on the case where X dominantly decays to e+e- as motivated by recent "dark force" models. In order to evade direct and indirect constraints, X must have small couplings to the standard model ([alpha]X ≤ 10-8) and a sufficiently large mass (mX ≥ 10 MeV). By comparing the signal and background cross sections for the $e-p e+e- final state, I conclude that dark force detection requires an integrated luminosity of around 1 ab-1. This proposal is currently being implements by the DarkLight collaboration at the Thomas Jefferson National Accelerator Facility. I also investigate the bounds on axion-like states from flavor-changing neutral current b → s decays, assuming the axion couples to the standard model through mixing with the Higgs sector. Such GeV-scale axions have received renewed attention in connection with observed cosmic ray excesses. I find that existing B → K l+l- data impose stringent bounds on the axion decay constant in the multi-TeV range, relevant for constraining the "axion portal" model of dark matter. Such bounds also constrain light Higgs scenarios in the next-to-minimal supersymmetric standard model. These bounds can be improved by dedicated searches in B-factory data and at LHCb. While looking at direct dark matter detection experiments themselves, it is often assumed that the first evidence for dark matter will come from experiments probing spin-independent interactions, with much higher sensitivities due to coherence effects. I explore models that would be invisible in such experiments, but detectable via spin-dependent interactions. The existence of much larger (or even only) spin-dependent tree-level interactions is not sufficient, due to potential spin-independent subdominant or loop-induced interactions, and I find that in this way most models with detectable spin-dependent interactions would also generate detectable spin-independent interactions. Models in which a light pseudoscalar acts as the mediator seem to uniquely evade this conclusion. In presenting a particular viable dark matter model generating such an interaction, a tens of MeV--GeV-scale axion is found to be an attractive candidate independently of considerations presented earlier.
Download or read book Dark Matter and Dark Energy written by Sabino Matarrese and published by Springer Science & Business Media. This book was released on 2011-02-10 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together reviews from leading international authorities on the developments in the study of dark matter and dark energy, as seen from both their cosmological and particle physics side. Studying the physical and astrophysical properties of the dark components of our Universe is a crucial step towards the ultimate goal of unveiling their nature. The work developed from a doctoral school sponsored by the Italian Society of General Relativity and Gravitation. The book starts with a concise introduction to the standard cosmological model, as well as with a presentation of the theory of linear perturbations around a homogeneous and isotropic background. It covers the particle physics and cosmological aspects of dark matter and (dynamical) dark energy, including a discussion of how modified theories of gravity could provide a possible candidate for dark energy. A detailed presentation is also given of the possible ways of testing the theory in terms of cosmic microwave background, galaxy redshift surveys and weak gravitational lensing observations. Included is a chapter reviewing extensively the direct and indirect methods of detection of the hypothetical dark matter particles. Also included is a self-contained introduction to the techniques and most important results of numerical (e.g. N-body) simulations in cosmology. " This volume will be useful to researchers, PhD and graduate students in Astrophysics, Cosmology Physics and Mathematics, who are interested in cosmology, dark matter and dark energy.
Download or read book Probing the Dark Sector written by Istvan Laszlo and published by . This book was released on 2012 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmology today is in a golden era, data is pouring in and exciting and challenging questions are being raised. We know that we live in an accelerating Universe populated largely by dark matter and dark energy, yet we have little information on the nature of either of these mysterious components. Theories abound and data is coming in with far greater quantity and precision than ever before and promises to enable distinguishing between these theories, however as we improve instruments we find ourselves plagued with how to effectively model signatures of the theories, and also how to truly interpret the data. Uncertainties in the nonlinear regime of theoretical predictions and in handling astrophysical systematics in observables are now emerging as leading issues that hinder constraining power. This thesis investigates the dark sector, considering first how one can approach the generation of correct nonlinear predictions for growth where gravity is modified (MG) in an attempt to explain the acceleration of the Universe. Next, we examine a possible Yukawa type self coupling of dark matter, motivated by the problems in small scale [LAMDA]CDM simulations of growth of structure, such as the cuspiness of halo density profiles and over production of small haloes. Finally, forecasts of constraining power for future surveys are made, in light of a key astrophysical systematic in weak lensing observations, namely the actual alignment of galaxies that form in the same halo which mixes in with the lensing signal in two ways, both generically summed up as Intrinsic Alignments(IA). We find that the standard approach of using fits developed in [LAMDA]CDM to generate nonlinear predicted matter power spectra for MG theories is valid, at least to mildly nonlinear scales. In the context of dark matter, there is no evidence against an interaction, yet also no preference for one. Finally for future survey forecasts, we find that previous forecasts were optimistic, and without a strong model for IA, additional probes will be required to compliment the weak lensing shear results and arrive at constraints similar to those derived from a survey in the absence of or with perfectly known IA contamination.
Download or read book Introduction to Modified Gravity written by Albert Petrov and published by Springer Nature. This book was released on 2023-11-16 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews various modified gravity models, including those with modifications in the pure gravitational sector; those involving extra fields, that is, scalar-tensor and vector-tensor gravity theories; gravity models with Lorentz symmetry breaking; and nonlocal gravity models. The authors discuss both classical and quantum aspects of these theories. The book is unique in bringing together all the current alternatives to Einstein gravity in one source and serves as an excellent starting point for graduate students and other newcomers seeking an overview. This second edition has been expanded with new results from a variety of approaches including f(R,Q,P) gravity, galileon gravity and massive gravity. Extended discussions of Lorentz-breaking terms and of non-local field theory have been added and a completely new chapter is devoted to models based on non-Riemannian geometry.
Download or read book Probes of Dark Matter from the Universe s Past and Present written by Chih-Liang Wu (Scientist in physics) and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are compelling evidences of gravitational effects from dark matter in cosmology and astronomy. By studying other imprints besides gravity, we might be able to infer its properties and interactions with Standard Model particles. This thesis explores how different dark matter models generate interesting observables and what can be learned by looking into various datasets. I demonstrate that novel techniques and datasets from indirect searches can be combined to set stringent constraints on the model parameters. In particular, this thesis details the calculations of constraints from two directions: on the one hand I will show how to constrain the rate of scattering, decay, and annihilation by taking advantage of cosmological observables including the Cosmic Microwave Background and the 21-cm neutral hydrogen line; on the other hand I will exploit astronomical datasets to infer properties of dark matter substructures and halo structures. The sources of the observables span a wide of range of cosmological time from cosmological recombination to the late-time universe, and they can be applied to probe complementary parameter space. With the upcoming precision measurements of astronomy, these novel ideas and calculations of indirect detections will lead insight into the nature of dark matter.
Download or read book Probing Macroscopic Dark Matter Parameter Space written by Jagjit Singh Sidhu and published by . This book was released on 2021 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Worlds New Horizons in Astronomy and Astrophysics written by National Research Council and published by National Academies Press. This book was released on 2011-02-04 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by discoveries, and enabled by leaps in technology and imagination, our understanding of the universe has changed dramatically during the course of the last few decades. The fields of astronomy and astrophysics are making new connections to physics, chemistry, biology, and computer science. Based on a broad and comprehensive survey of scientific opportunities, infrastructure, and organization in a national and international context, New Worlds, New Horizons in Astronomy and Astrophysics outlines a plan for ground- and space- based astronomy and astrophysics for the decade of the 2010's. Realizing these scientific opportunities is contingent upon maintaining and strengthening the foundations of the research enterprise including technological development, theory, computation and data handling, laboratory experiments, and human resources. New Worlds, New Horizons in Astronomy and Astrophysics proposes enhancing innovative but moderate-cost programs in space and on the ground that will enable the community to respond rapidly and flexibly to new scientific discoveries. The book recommends beginning construction on survey telescopes in space and on the ground to investigate the nature of dark energy, as well as the next generation of large ground-based giant optical telescopes and a new class of space-based gravitational observatory to observe the merging of distant black holes and precisely test theories of gravity. New Worlds, New Horizons in Astronomy and Astrophysics recommends a balanced and executable program that will support research surrounding the most profound questions about the cosmos. The discoveries ahead will facilitate the search for habitable planets, shed light on dark energy and dark matter, and aid our understanding of the history of the universe and how the earliest stars and galaxies formed. The book is a useful resource for agencies supporting the field of astronomy and astrophysics, the Congressional committees with jurisdiction over those agencies, the scientific community, and the public.
Download or read book Probing Dark Matter with Strong Gravitational Lensing written by Simon Birrer and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Generalized Perturbations in Modified Gravity and Dark Energy written by Jonathan Pearson and published by Springer. This book was released on 2016-08-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When predictions of Einstein's theory of General Relativity are compared against observations of our Universe, a huge inconsistency is found. The most popular fix for this inconsistency is to "invent" around 94% of the content of the universe: dark matter and dark energy. The dark energy is some exotic substance responsible for the apparent observed acceleration of the Universe. Another fix is to modify the theory of gravity: it is entirely plausible that Einstein's theory of General Relativity breaks down on cosmological scales, just as Newton's theory of gravity breaks down in the extreme gravitational field of the Sun. There are many alternative theories of gravity, each with the aim of describing observations of our Universe where General Relativity fails. Whether it is dark energy or some modified theory of gravity, it is clear that there is some "dark sector" in the Universe. In this thesis the author constructs a unifying framework for understanding the observational impact of general classes of dark sector theories, by formulating equations of state for the dark sector perturbations.
Download or read book Generalized Perturbations in Modified Gravity and Dark Energy written by Jonathan Andrew Pearson and published by . This book was released on 2013-10-31 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: When recent observational data and the GR+FRW+CDM model are combined we obtain the result that the Universe is accelerating, where the acceleration is due to some not-yet-understood "dark sector". There has been a considerable number of theoretical models constructed in an attempt to provide a description of the dark sector: dark energy and modified gravity theories. The proliferation of modified gravity and dark energy models has brought to light the need to construct a "generic" way to parameterize perturbations in the dark sector. In this thesis we discuss our new way of approaching this problem. We write down an effective action for linearized perturbations to the gravitational field equations for a given field content and use it to compute generalized gravitational field equations for linearized perturbations. Our approach is inspired by that taken in particle physics, where the most general modifications to the standard model are written down for a given field content that is compatible with some assumed symmetry (which we take to be isotropy of the background spatial sections). After applying the formalism we obtain equations of state for dark sector perturbations, where the number of free parameters for wide classes of theories are identified.
Download or read book Modified Gravity and the Phantom of Dark Matter written by Joel Richard Brownstein and published by . This book was released on 2009 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrophysical data analysis of the weak-field predictions support the claim that modified gravity (MOG) theories provide a self-consistent, scale-invariant, universal description of galaxy rotation curves, without the need of non-baryonic dark matter. Comparison to the predictions of Milgrom's modified dynamics (MOND) provide a best-fit and experimentally determined universal value of the MOND acceleration parameter. The predictions of the modified gravity theories are compared to the predictions of cold non-baryonic dark matter (CDM), including a constant density core-modified fitting formula, which produces excellent fits to galaxy rotation curves including the low surface brightness and dwarf galaxies. Upon analysing the mass profiles of clusters of galaxies inferred from X-ray luminosity measurements, from the smallest nearby clusters to the largest of the clusters of galaxies, it is shown that while MOG provides consistent fits, MOND does not fit the observed shape of cluster mass profiles for any value of the MOND acceleration parameter. Comparison to the predictions of CDM confirm that whereas the Navarro-Frenk-White (NFW) fitting formula does not fit the observed shape of galaxy cluster mass profiles, the core-modified dark matter fitting formula provides excellent best-fits, supporting the hypothesis that baryons are dynamically important in the distribution of dark matter halos.
Download or read book Model independent Probes of Cosmology Gravitation written by C. Pittordis and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Probing Dark Matter with Intrinsic and Extrinsic Galaxy Alignments written by Michael Loyola Brown and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Probing Dark Matter with Resonant Dynamics of the Galactic Bar written by Rimpei Chiba and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
