Download or read book Dark Matter Constraints from Observations of 25 Milky Way Satellite Galaxies with the Fermi Large Area Telescope written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dwarf spheroidal satellite galaxies of the Milky Way are some of the most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are widely considered to be among the most promising targets for the indirect detection of dark matter via gamma rays. Here we report on gamma-ray observations of 25 Milky Way dwarf spheroidal satellite galaxies based on 4 years of Fermi Large Area Telescope (LAT) data. None of the dwarf galaxies are significantly detected in gamma rays, and we present gamma-ray flux upper limits between 500 MeV and 500 GeV. We determine the dark matter content of 18 dwarf spheroidal galaxies from stellar kinematic data and combine LAT observations of 15 dwarf galaxies to constrain the dark matter annihilation cross section. We set some of the tightest constraints to date on the the annihilation of dark matter particles with masses between 2 GeV and 10 TeV into prototypical Standard Model channels. We find these results to be robust against systematic uncertainties in the LAT instrument performance, diffuse gamma-ray background modeling, and assumed dark matter density profile.

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.

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 Searching for Dark Matter with Cosmic Gamma Rays written by Andrea Albert and published by Morgan & Claypool Publishers. This book was released on 2016-09-06 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Searching for Dark Matter with Cosmic Gamma Rays summarizes the evidence for dark matter and what we can learn about its particle nature using cosmic gamma rays. It has almost been 100 years since Fritz Zwicky first detected hints that most of the matter in the Universe that doesn't directly emit or reflect light. Since then, the observational evidence for dark matter has continued to grow. Dark matter may be a new kind of particle that is governed by physics beyond our Standard Model of particle physics. In many models, dark matter annihilation or decay produces gamma rays. There are a variety of instruments observing the gamma-ray sky from tens of MeV to hundreds of TeV. Some make deep, focused observations of small regions, while others provide coverage of the entire sky. Each experiment offers complementary sensitivity to dark matter searches in a variety of target sizes, locations, and dark matter mass scales. We review results from recent gamma-ray experiments including anomalies some have attributed to dark matter. We also discuss how our gamma-ray observations complement other dark matter searches and the prospects for future experiments.

Download or read book Aspects of WIMP Dark Matter Searches at Colliders and Other Probes written by Enrico Morgante and published by Springer. This book was released on 2017-10-05 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis covers several theoretical aspects of WIMP (weakly interacting massive particles) dark matter searches, with a particular emphasis on colliders. It mainly focuses on the use of effective field theories as a tool for Large Hadron Collider (LHC) searches, discussing in detail the issue of their validity, and on simplified dark matter models, which are receiving a growing attention from the physics community. It highlights the theoretical consistency of simplified models, which is essential in order to correctly exploit their potential and for them to be a common reference when comparing results from different experiments. This thesis is of interest to researchers (both theorists and experimentalists) in the field of dark matter searches, and offers a comprehensive introduction to dark matter and to WIMP searches for students and non-experts.

Download or read book Optimized Dark Matter Searches in Deep Observations of Segue 1 with MAGIC written by Jelena Aleksić and published by Springer. This book was released on 2015-11-06 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the results of indirect dark matter searches in the gamma-ray sky of the near Universe, as seen by the MAGIC Telescopes. The author has proposed and led the 160 hours long observations of the dwarf spheroidal galaxy Segue 1, which is the deepest survey of any such object by any Cherenkov telescope so far. Furthermore, she developed and completely characterized a new method, dubbed “Full Likelihood”, that optimizes the sensitivity of Cherenkov instruments for detection of gamma-ray signals of dark matter origin. Compared to the standard analysis techniques, this novel approach introduces a sensitivity improvement of a factor of two (i.e. it requires 4 times less observation time to achieve the same result). In addition, it allows a straightforward merger of results from different targets and/or detectors. By selecting the optimal observational target and combining its very deep exposure with the Full Likelihood analysis of the acquired data, the author has improved the existing MAGIC bounds to the dark matter properties by more than one order of magnitude. Furthermore, for particles more massive than a few hundred GeV, those are the strongest constraints from dwarf galaxies achieved by any gamma-ray instrument, both ground-based or space-borne alike.

Download or read book Dark Matter Searches with the Fermi LAT in the Direction of Dwarf Spheroidals written by and published by . This book was released on 2015 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Search for Dark Matter with the ATLAS Detector written by Johanna Gramling and published by Springer. This book was released on 2018-08-01 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses searches for Dark Matter at the CERN’s LHC, the world’s most powerful accelerator. It introduces the relevant theoretical framework and includes an in-depth discussion of the Effective Field Theory approach to Dark Matter production and its validity, as well as an overview of the formalism of Simplified Dark Matter models. Despite overwhelming astrophysical evidence for Dark Matter and numerous experimental efforts to detect it, the nature of Dark Matter still remains a mystery and has become one of the hottest research topics in fundamental physics. Two searches for Dark Matter are presented, performed on data collected with the ATLAS experiment. They analyze missing-energy final states with a jet or with top quarks. The analyses are explained in detail, and the outcomes and their interpretations are discussed, also in view of the precedent analysis of theoretical approaches. Given its depth of coverage, the book represents an excellent reference guide for all physicists interested in understanding the theoretical and experimental considerations relevant to Dark Matter searches at the LHC.

Download or read book Search for Dark Matter with ATLAS written by Ruth Pöttgen and published by Springer. This book was released on 2016-06-29 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes in detail a search for weakly interacting massive particles as possible dark matter candidates, making use of so-called mono-jet events. It includes a detailed description of the run-1 system, important operational challenges, and the upgrade for run-2. The nature of dark matter, which accounts for roughly 25% of the energy-matter content of the universe, is one of the biggest open questions in fundamental science. The analysis is based on the full set of proton-proton collisions collected by the ATLAS experiment at the Large Hadron Collider at √s = 8 TeV. Special attention is given to the experimental challenges and analysis techniques, as well as the overall scientific context beyond particle physics. The results complement those of non-collider experiments and yield some of the strongest exclusion bounds on parameters of dark matter models by the end of the Large Hadron Collider run-1. Details of the upgrade of the ATLAS Central Trigger for run-2 are also included.

Download or read book Searching for Dark Matter Annihilation from Milky Way Dwarf Spheroidal Galaxies with Six Years of Fermi Large Area Telescope Data written by 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 Searching for Dark Matter with the ATLAS Detector written by Steven Schramm and published by Springer. This book was released on 2016-11-23 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the search for Dark Matter at the LHC in the mono-jet plus missing transverse momentum final state, using the full dataset recorded in 2012 by the ATLAS Experiment. It is the first time that the number of jets is not explicitly restricted to one or two, thus increasing the sensitivity to new signals. Instead, a balance between the most energetic jet and the missing transverse momentum is required, thus selecting mono-jet-like final states. Collider searches for Dark Matter have typically used signal models employing effective field theories (EFTs), even when comparing to results from direct and indirect detection experiments, where the difference in energy scale renders many such comparisons invalid. The thesis features the first robust and comprehensive treatment of the validity of EFTs in collider searches, and provides a means by which the different classifications of Dark Matter experiments can be compared on a sound and fair basis.

Download or read book Science With The Cherenkov Telescope Array written by The Cta Consortium and published by World Scientific. This book was released on 2018-12-31 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the science to be carried out by the upcoming Cherenkov Telescope Array, a major ground-based gamma-ray observatory that will be constructed over the next six to eight years. The major scientific themes, as well as core program of key science projects, have been developed by the CTA Consortium, a collaboration of scientists from many institutions worldwide.CTA will be the major facility in high-energy and very high-energy photon astronomy over the next decade and beyond. CTA will have capabilities well beyond past and present observatories. Thus, CTA's science program is expected to be rich and broad and will complement other major multiwavelength and multimessenger facilities. This book is intended to be the primary resource for the science case for CTA and it thus will be of great interest to the broader physics and astronomy communities. The electronic version (e-book) is available in open access.

Download or read book Higgs Supersymmetry and Dark Matter After Run I of the LHC written by Béranger Dumont and published by Springer. This book was released on 2016-09-21 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work was nominated as an outstanding PhD thesis by the LPSC, Université Grenoble Alpes, France. The LHC Run 1 was a milestone in particle physics, leading to the discovery of the Higgs boson, the last missing piece of the so-called "Standard Model" (SM), and to important constraints on new physics, which challenge popular theories like weak-scale supersymmetry. This thesis provides a detailed account of the legacy of the LHC Run 1 ≤¥regarding these aspects. First, the SM and the need for its extension are presented in a concise yet revealing way. Subsequently, the impact of the LHC Higgs results on scenarios of new physics is assessed in detail, including a careful discussion of the relevant uncertainties. Two approaches are considered: generic modifications of the Higgs couplings, possibly arising from extended Higgs sectors or higher-dimensional operators; and tests of specific new physics models. Lastly, the implications of the null results of the searches for new physics are discussed with a particular focus on supersymmetric dark matter candidates. Here as well, two approaches are presented: the "simplified models" approach, and recasting by event simulation. This thesis stands out for its educational approach, its clear language and the depth of the physics discussion. The methods and tools presented offer readers essential practical tools for future research.

Download or read book Constraints on Dark Matter and Milky Way Satellite Galaxies from Cosmological Simulations written by Miguel Eduardo Rocha Gaso and published by . This book was released on 2014 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmological simulations describing the non-linear evolution of dark matter structures in the Universe have become an indispensable tool to study the predictions made by our standard model of cosmology, and to confront them with observations. In this thesis I present a new idea for using cosmological simulations to infer the accretion times of Milky Way satellite galaxies from their observed positions and kinematics. We find that Carina, Ursa Minor, and Sculptor were all accreted early, more than 8 Gyr ago. Five other dwarfs, including Sextans and Segue 1, are also probable early accreters, though with larger uncertainties. On the other extreme, Leo T is just falling into the Milky Way for the first time while Leo I fell ~2 Gyr ago and is now climbing out of the Milky Way's potential after its first perigalacticon. The energies of several other dwarfs, including Fornax and Hercules, point to intermediate infall times, 2 - 8 Gyr ago. Our analysis suggests that the Large Magellanic Cloud crossed inside the Milky Way virial radius recently, within the last ~4 billion years. Also I present new constrains on how strongly dark matter particles can interact with themselves. For this we use a set cosmological simulations that implement a new self-consistent algorithm to treat dark matter self-interactions. We find that self-interacting dark matter models with cross sections in the order [sigma]/m ~ 0.5 cm2 /g ~ 1 barn/GeV would be capable of reproducing the observed core sizes and central densities of dark matter halos in a wide range of scales, from tiny dwarf galaxies to large galaxy clusters, without violating any other observational constraints. Higher resolution simulations over a wider range of masses and properly accounting for the effects of baryonic processes that are not yet included in our simulation will be required to confirm our expectations and place better constraints. I discuss our plans for achieving this goal and show some preliminary results from a new set of simulations.

Download or read book Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope written by and published by . This book was released on 2012 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10−26 cm3 s−1 at 5 GeV to about 5 x 10−23 cm3 s−1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (≈3 x 10−26 cm3 s−1 for a purely s-wave cross section), without assuming additional boost factors.

Download or read book Production Yield of Muon Induced Neutrons in Lead written by Holger Kluck and published by Springer. This book was released on 2015-07-28 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this book is a major step towards understanding and eventually suppressing background in the direct search for dark matter particles scattering off germanium detectors. Although the flux of cosmic muons is reduced by many orders of magnitude in underground laboratories, the remaining energetic muons induce neutrons through various processes, neutrons that can potentially mimic a dark matter signal. This thesis describes the measurement of muon-induced neutrons over more than 3 years in the Modane underground laboratory. The data are complemented by a thorough modeling of the neutron signal using the GEANT4 simulation package, demonstrating the appropriateness of this tool to model these rare processes. As a result, a precise neutron production yield can be presented. Thus, future underground experiments will be able to reliably model the expected rate of muon-induced neutrons, making it possible to develop the necessary shielding concept to suppress this background component.

Download or read book Searching for Dwarf Spheroidal Galaxies and Other Galactic Dark Matter Substructures with the Fermi Large Area Telescope written by and published by . This book was released on 2013 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past century, it has become clear that about a quarter of the known universe is composed of an invisible, massive component termed ''dark matter''. Some of the most popular theories of physics beyond the Standard Model suggest that dark matter may be a new fundamental particle that could self-annihilate to produce [gamma] rays. Nearby over-densities in the dark matter halo of our Milky Way present some of the most promising targets for detecting the annihilation of dark matter. We used the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope to search for [gamma] rays produced by dark matter annihilation in Galactic dark matter substructures. We searched for [gamma]-ray emission coincident with Milky Way dwarf spheroidal satellite galaxies, which trace the most massive Galactic dark matter substructures. We also sought to identify nearby dark matter substructures that lack all astrophysical tracers and would be detectable only through [gamma]-ray emission from dark matter annihilation. We found no conclusive evidence for [gamma]-ray emission from dark matter annihilation, and we set stringent and robust constraints on the dark matter annihilation cross section. While [gamma]-ray searches for dark matter substructure are currently the most sensitive and robust probes of dark matter annihilation, they are just beginning to intersect the theoretically preferred region of dark matter parameter space. Thus, we consider future prospects for increasing the sensitivity of [gamma]-ray searches through improvements to the LAT instrument performance and through upcoming wide- field optical surveys.