Search for Gamma-ray Spectral Lines with the Fermi Large Area Telescope and Dark Matter Implications PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Search for Gamma-ray Spectral Lines with the Fermi Large Area Telescope and Dark Matter Implications PDF full book. Access full book title Search for Gamma-ray Spectral Lines with the Fermi Large Area Telescope and Dark Matter Implications by Andrea Marie Albert. Download full books in PDF and EPUB format.
Author: Andrea Marie Albert
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Abstract: Measurements indicate that ~85% of the matter in the universe neither emits nor reflects light--appropriately called "dark matter". We believe dark matter may be primary composed of new particles, but we know very little about their nature. What dark matter is and how it interacts is one of the top cosmological mysteries today. Detecting a signal from particle dark matter would not only offer insight into the fundamental nature of dark matter, but it would also be strong evidence for physics existing beyond the Standard Model. A promising dark matter candidate is a weakly interacting massive particle (WIMP). Measurements indicate that the Milky Way Galaxy resides in a halo of dark matter, making it an ideal laboratory for investigating these elusive particles. As WIMPs are predicted to be heavy, their interactions should produce high-energy gamma rays that would be detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (Fermi). If WIMPs annihilate directly into gamma rays, the gamma-ray energy would be the same as the rest mass energy of the WIMPs, which is currently unknown. This process would cause a "pile-up" of gamma rays at a specific energy, producing a sharp line (or bump) in the otherwise relatively smooth gamma-ray energy spectrum. This distinctive signal would not only be strong evidence for the existence of WIMPs, but would also provide information about their mass. We have searched for spectral lines in the energy range 5 to 300 GeV using 3.7 years of Fermi LAT data, reprocessed with updated calorimeter calibration constants, and an improved energy dispersion model from previous LAT Collaboration line searches. We search in five regions selected to optimize sensitivity to different theoretically-motivated density distributions of WIMPs. We do not find any globally significant lines in our a priori search regions and present 95% confidence limits for annihilation cross section and decay lifetimes. We extensively discuss potential systematic effects in the search. Finally, we consider claims of evidence for a spectral line at 130 GeV, compare our results to previous work, and discuss why this search finds a somewhat lower statistical significance for a potential line than other works.
Author: Andrea Marie Albert
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Abstract: Measurements indicate that ~85% of the matter in the universe neither emits nor reflects light--appropriately called "dark matter". We believe dark matter may be primary composed of new particles, but we know very little about their nature. What dark matter is and how it interacts is one of the top cosmological mysteries today. Detecting a signal from particle dark matter would not only offer insight into the fundamental nature of dark matter, but it would also be strong evidence for physics existing beyond the Standard Model. A promising dark matter candidate is a weakly interacting massive particle (WIMP). Measurements indicate that the Milky Way Galaxy resides in a halo of dark matter, making it an ideal laboratory for investigating these elusive particles. As WIMPs are predicted to be heavy, their interactions should produce high-energy gamma rays that would be detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope (Fermi). If WIMPs annihilate directly into gamma rays, the gamma-ray energy would be the same as the rest mass energy of the WIMPs, which is currently unknown. This process would cause a "pile-up" of gamma rays at a specific energy, producing a sharp line (or bump) in the otherwise relatively smooth gamma-ray energy spectrum. This distinctive signal would not only be strong evidence for the existence of WIMPs, but would also provide information about their mass. We have searched for spectral lines in the energy range 5 to 300 GeV using 3.7 years of Fermi LAT data, reprocessed with updated calorimeter calibration constants, and an improved energy dispersion model from previous LAT Collaboration line searches. We search in five regions selected to optimize sensitivity to different theoretically-motivated density distributions of WIMPs. We do not find any globally significant lines in our a priori search regions and present 95% confidence limits for annihilation cross section and decay lifetimes. We extensively discuss potential systematic effects in the search. Finally, we consider claims of evidence for a spectral line at 130 GeV, compare our results to previous work, and discuss why this search finds a somewhat lower statistical significance for a potential line than other works.
Author: Yvonne Vasetta Edmonds
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 161
Get Book Here
Book Description
The most popular class of dark matter candidates is the class of weakly-interacting massive particles (WIMPs). The Fermi Large Area Telescope has the possibility of indirectly detecting WIMPs by the flux from their annihilation/decay products. When a WIMP annihilates or decays directly into a photon gamma and another particle Y the photons are monochromatic. Detection of the resulting spectral line(s) would provide convincing evidence for particulate dark matter and could provide the WIMP mass. In the case of no detection, knowledge of the dark matter distribution can be used to place limits on the annihilation cross section and lifetime for the WIMP(s) to Y-gamma channel. We present the spectrum from 4.8 to 264 GeV and spectral line flux upper limits, obtained from a subset of this spectrum, from 7 to 200 GeV. The spatial region of the dataset covers a large portion of the sky, the high latitudes plus the Galactic Center. We report upper limits on the WIMP cross sections for annihilation to gamma-gamma and Z-gamma and lower limits on the WIMP lifetime for decay to gamma-neutrino. We discuss the implications of the spectrum and line flux limits for several dark matter models with optimistic branching ratios for photon channels.
Author: Andrea Albert
Publisher: Morgan & Claypool Publishers
ISBN: 1681742705
Category : Science
Languages : en
Pages : 82
Get Book Here
Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
Get Book Here
Book Description
There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce [gamma] rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for [gamma]-ray spectral lines and [gamma]-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.
Author: Jelena Aleksić
Publisher: Springer
ISBN: 3319231235
Category : Science
Languages : en
Pages : 213
Get Book Here
Book Description
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.
Author: Wang Ping
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 167
Get Book Here
Book Description
This thesis focuses on the search for unknown dark matter (DM) satellites in the Milky Way using the Fermi Large Area Space Telescope (LAT). The Fermi Gamma-ray Space Telescope (Fermi) is a next generation space observatory, which was successfully launched on June 11th, 2008. The LAT is the principal scientific instrument onboard. Its unprecedented angular resolution and sensitivity in the 100 MeV to > 300 GeV energy range makes it an excellent instrument for probing the sky for DM satellites. Current N-body simulations based on the Lambda-CDM cosmology model predict a large number of as yet unobserved DM satellites in our galaxy; some satellites are predicted to be extended sources (> 1deg extension) as seen by the LAT. Our work assumes that a significant component of DM is a Weakly Interacting Massive Particle (WIMP) in the 100 GeV mass range. The annihilation of WIMPs results in many high energy gamma rays that can be well measured by the LAT. The WIMP produced gamma-ray spectrum from the putative DM satellites is considerably harder than most astrophysical sources. Also, DM satellites have no astronomical counterparts in the X-ray and radio bands, and the emission has no time variability. My thesis will focus on a blind analysis in the search for unknown DM satellites using one year of LAT data, and setting constraints on some WIMP models based on the results of our analysis in which we find no candidates.
Author: Yvonne Vasetta Edmonds
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The most popular class of dark matter candidates is the class of weakly-interacting massive particles (WIMPs). The Fermi Large Area Telescope has the possibility of indirectly detecting WIMPs by the flux from their annihilation/decay products. When a WIMP annihilates or decays directly into a photon gamma and another particle Y the photons are monochromatic. Detection of the resulting spectral line(s) would provide convincing evidence for particulate dark matter and could provide the WIMP mass. In the case of no detection, knowledge of the dark matter distribution can be used to place limits on the annihilation cross section and lifetime for the WIMP(s) to Y-gamma channel. We present the spectrum from 4.8 to 264 GeV and spectral line flux upper limits, obtained from a subset of this spectrum, from 7 to 200 GeV. The spatial region of the dataset covers a large portion of the sky, the high latitudes plus the Galactic Center. We report upper limits on the WIMP cross sections for annihilation to gamma-gamma and Z-gamma and lower limits on the WIMP lifetime for decay to gamma-neutrino. We discuss the implications of the spectrum and line flux limits for several dark matter models with optimistic branching ratios for photon channels.
Author: Steven Schramm
Publisher: Springer
ISBN: 3319444530
Category : Science
Languages : en
Pages : 341
Get Book Here
Book Description
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.
Author: Yann Mambrini
Publisher: Springer Nature
ISBN: 3030781399
Category : Science
Languages : en
Pages : 518
Get Book Here
Book Description
This book provides a comprehensive and instructive coverage of particle physics in the early universe, in a logical way. It starts from the thermal history of the universe by investigating some of the main arguments such as Big Bang nucleosynthesis, the cosmic microwave background (CMB) and the inflation, before treating in details the direct and indirect detection of dark matter and then some aspects of the physics of neutrino. Following, it describes possible candidates for dark matter and its interactions. The book is targeted at theoretical physicists who deal with particle physics in the universe, dark matter detection and astrophysical constraints, and at particle physicists who are interested in models of inflation or reheating. This book offers also material for astrophysicists who work with quantum field theory computations. All that is useful to compute any physical process is included: mathematical tables, all the needed functions for the thermodynamics of early universe and Feynman rules. In light of this, this book acts as a crossroad between astrophysics, particle physics and cosmology.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The Fermi Gamma-Ray Space Telescope has been scanning the gamma ray sky since it was launched by NASA in June 2008 and has a mission lifetime goal of 10 years. Largely due to our particle physics heritage, one of the main physics topics being studied by the Fermi LAT Collaboration is the search for dark matter via indirect detection. My talk will review the progress of these studies, something on how the LAT detector enables them, and expectations for the future. I will discuss both gamma-ray and (electron + positron) searches for dark matter, and some resulting theoretical implications.
