DOCSLIB.ORG

Formation of Structure in Dark Energy Cosmologies

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Formation of Structure in Dark Energy Cosmologies HELSINKI INSTITUTE OF PHYSICS INTERNAL REPORT SERIES HIP-2006-08 Formation of Structure in Dark Energy Cosmologies Tomi Sebastian Koivisto Helsinki Institute of Physics, and Division of Theoretical Physics, Department of Physical Sciences Faculty of Science University of Helsinki P.O. Box 64, FIN-00014 University of Helsinki Finland ACADEMIC DISSERTATION To be presented for public criticism, with the permission of the Faculty of Science of the University of Helsinki, in Auditorium CK112 at Exactum, Gustaf H¨allstr¨omin katu 2, on November 17, 2006, at 2 p.m.. Helsinki 2006 ISBN 952-10-2360-9 (printed version) ISSN 1455-0563 Helsinki 2006 Yliopistopaino ISBN 952-10-2961-7 (pdf version) http://ethesis.helsinki.fi Helsinki 2006 Helsingin yliopiston verkkojulkaisut Contents Abstract vii Acknowledgements viii List of publications ix 1 Introduction 1 1.1Darkenergy:observationsandtheories..................... 1 1.2Structureandcontentsofthethesis...................... 6 2Gravity 8 2.1Generalrelativisticdescriptionoftheuniverse................. 8 2.2Extensionsofgeneralrelativity......................... 10 2.2.1 Conformalframes............................ 13 2.3ThePalatinivariation.............................. 15 2.3.1 Noethervariationoftheaction..................... 17 2.3.2 Conformalandgeodesicstructure.................... 18 3 Cosmology 21 3.1Thecontentsoftheuniverse........................... 21 3.1.1 Darkmatter............................... 22 3.1.2 Thecosmologicalconstant........................ 23 3.2Alternativeexplanations............................. 24 3.2.1 Quintessence............................... 25 3.2.2 Quartessence............................... 26 3.2.3 Gravitationaldarkenergy........................ 28 3.2.4 Darkenergyfrombackreaction..................... 30 4Perturbations 33 4.1Gauges....................................... 33 4.2Scalarperturbations............................... 37 4.3CMBPhysics................................... 40 4.3.1 Themultipoleexpansion......................... 40 4.3.2 Recombination.............................. 43 iii CONTENTS iv 5 Parameterizations 46 5.1ModifiedFriedmannequations......................... 48 5.1.1 CaseII:assuminginteractions...................... 49 5.1.2 CaseIII:assumingextradimensions.................. 51 5.2Fluiddarkenergy................................. 54 5.2.1 Models with −1 <w<0 ........................ 56 5.2.2 Phantom models with w<−1 ..................... 60 2 5.2.3 Models with cs < 0............................ 60 5.2.4 Asummary................................ 61 6Models 63 6.1 Gauss-Bonnet gravity: Stability of perturbations . ............. 63 6.2Isocurvaturequintessence:ISW-LSScorrelation................ 68 6.3Gravitationaldarkenergy:Matterpowerspectrum.............. 70 7 Summary 77 A Conformal transformation 79 B Perturbed FRW metric 82 B.1Velocitiesandviscosities............................. 83 List of Figures 3.1 Confidence contours arising from matching the CMB peak locations for f(R)gravity.................................... 30 4.1RecombinationofHydrogen............................ 45 5.1Darkenergyperturbationsintwogauges.................... 57 5.2Phantomdarkenergyperturbationsintwogauges............... 57 5.3CMBtemperatureanisotropieswithdarkenergy................ 59 5.4 CMB temperature anisotropies with phantom dark energy. 59 6.1ConstraintsforGauss-Bonnetdarkenergy.................... 65 6.2 Effective gravitational constant and the growth rate of perturbations for Gauss-Bonnetdarkenergy............................ 66 6.3 Contributions to the ISW-LSS cross correlation with and without quintessence isocurvature.................................... 70 6.4 CMB anisotropies and matter power spectrum with and without quintessence isocurvature.................................... 71 6.5ISW-LSScrosscorrelationsinvariousmodels.................. 72 6.6 Confidence contours arising from matching the matter power spectrum for f(R)gravity.................................... 73 v List of Tables 2.1Actionsforgeneralizedgravitytheories..................... 12 3.1Quintessencemodels................................ 26 3.2Unifiedmodelsofdarkmatteranddarkenergy................. 27 5.1Summarizingfluiddarkenergy.......................... 61 vi Koivisto, Tomi: Formation of Structure in Dark Energy Cosmologies, University of Helsinki, 2006, 115 p., Helsinki Institute of Physics Internal Report Series, HIP-2006-08, ISSN 1455-0563, ISBN 952-10-2360-9 (printed version), ISBN 952-10-2961-7 (pdf version). Classification (pacs): 98.80.-k,98.80.Jk, 95.36.+x, 98.80.Es, 95.30.Sf, 04.20.-q Keywords: Cosmology: Theory, Large-Scale Structure of Universe, Dark Energy, Scalar-tensor theories, Cosmic microwave background, Cosmological perturbations, Modified gravity, Variational principles in relativity Abstract Acceleration of the universe has been established but not explained. During the past few years precise cosmological experiments have confirmed the standard big bang scenario of a flat universe undergoing an inflationary expansion in its earliest stages, where the per- turbations are generated that eventually form into galaxies and other structure in matter, most of which is non-baryonic dark matter. Curiously, the universe has presently entered into another period of acceleration. Such a result is inferred from observations of extra- galactic supernovae and is independently supported by the cosmic microwave background radiation and large scale structure data. It seems there is a positive cosmological constant speeding up the universal expansion of space. Then the vacuum energy density the constant describes should be about a dozen times the present energy density in visible matter, but particle physics scales are enormously larger than that. This is the cosmological constant problem, perhaps the greatest mystery of contemporary cosmology. In this thesis we will explore alternative agents of the acceleration. Generically, such are called dark energy. If some symmetry turns off vacuum energy, its value is not a problem but one needs some dark energy. Such could be a scalar field dynamically evolving in its potential, or some other exotic constituent exhibiting negative pressure. Another option is to assume that gravity at cosmological scales is not well described by general relativity. In a modified theory of gravity one might find the expansion rate increasing in a universe filled by just dark matter and baryons. Such possibilities are taken here under investigation. The main goal is to uncover observational consequences of different models of dark energy, the emphasis being on their implications for the formation of large-scale structure of the universe. Possible properties of dark energy are investigated using phenomenological paramaterizations, but several specific models are also considered in detail. Difficulties in unifying dark matter and dark energy into a single concept are pointed out. Considerable attention is on modifications of gravity resulting in second order field equations. It is shown that in a general class of such models the viable ones represent effectively the cosmological constant, while from another class one might find interesting modifications of the standard cosmological scenario yet allowed by observations. The thesis consists of seven research papers preceded by an introductory discussion. vii Acknowledgements I would like to thank my supervisors dr. Hannu Kurki-Suonio and prof. Finn Ravndal. Hannu’s lucid teaching of cosmology and reliable guidance have continuously been of great help in my studies and in preparation of this dissertation. I am also very grateful to Finn, whose encouragement and insights to physics were an invaluable stimulus for my research. In addition, I have benefitted much from advices and arrangements of prof. Kari Enqvist. I wish to thank dr. David Mota for inspirational collaborations. I thank the referees of the thesis, profs. Øystein Elgarøy and Kimmo Kainulainen, for their careful reading of the manuscript. Helsinki Institute of Physics and the Theoretical Physics Division of the Department of Physical Sciences at the University of Helsinki have provided a pleasant working environ- ment. Thanks go to their personnel. For instance, discussions with Sami, Teppo and Torsti and my officemates Lotta, Janne, Touko, Vappu and Vesa have been helpful and amusing. I am also grateful to the people at Theoretical Physics Division at the Department of Physics and Institute of Theoretical Astrophysics of the Oslo University for their kind hospitality during my stay in Oslo the academic year 2004–2005. I especially thank the students and graduate students, H˚avard, Petter, Morad and others. In addition, I thank Kreivi and Raato for technical support; Thomas Sotiriou for enlightening correspondance; Puukko, Kanalja and others at the Interzone for interesting conversations; Simo and Riku for musical diversions; and Sky Lee for useful comments. I thankfully acknowledge financial support from the Finnish Cultural Foundation, Mag- nus Ehrnrooth Foundation, NordForsk, Waldemar von Frenckells Stiftelse and Emil Aal- tosen S¨a¨ati¨o. Finally, my very special thanks to Paula, Sinikka and Voitto, to my cherished wife Silja Matilda Koivisto and to her parents. Tomi Koivisto Helsinki, October 2006 viii List of publications This thesis is based on the following papers. [1] The CMB spectrum in Cardassian models. With Hannu Kurki-Suonio and Finn Ravndal Phys.Rev.D71:064027,2005 [astro-ph/0409163] [2] Growth of perturbations in dark matter coupled with quintessence. Phys.Rev.D72:043516,2005
Load more

Recommended publications
  • Galaxies 2013, 1, 1-5; Doi:10.3390/Galaxies1010001
    Galaxies 2013, 1, 1-5; doi:10.3390/galaxies1010001 OPEN ACCESS galaxies ISSN 2075-4434 www.mdpi.com/journal/galaxies Editorial Galaxies: An International Multidisciplinary Open Access Journal Emilio Elizalde Consejo Superior de Investigaciones Científicas, Instituto de Ciencias del Espacio & Institut d’Estudis Espacials de Catalunya, Faculty of Sciences, Campus Universitat Autònoma de Barcelona, Torre C5-Parell-2a planta, Bellaterra (Barcelona) 08193, Spain; E-Mail: [email protected]; Tel.: +34-93-581-4355 Received: 23 October 2012 / Accepted: 1 November 2012 / Published: 8 November 2012 The knowledge of the universe as a whole, its origin, size and shape, its evolution and future, has always intrigued the human mind. Galileo wrote: “Nature’s great book is written in mathematical language.” This new journal will be devoted to both aspects of knowledge: the direct investigation of our universe and its deeper understanding, from fundamental laws of nature which are translated into mathematical equations, as Galileo and Newton—to name just two representatives of a plethora of past and present researchers—already showed us how to do. Those physical laws, when brought to their most extreme consequences—to their limits in their respective domains of applicability—are even able to give us a plausible idea of how the origin of our universe came about and also of how we can expect its future to evolve and, eventually, how its end will take place. These laws also condense the important interplay between mathematics and physics as just one first example of the interdisciplinarity that will be promoted in the Galaxies Journal. Although already predicted by the great philosopher Immanuel Kant and others before him, galaxies and the existence of an “Island Universe” were only discovered a mere century ago, a fact too often forgotten nowadays when we deal with multiverses and the like.
    [Show full text]
  • Parallel Sessions
    Identification of Dark Matter July 23-27, 2012 9th International Conference Chicago, IL http://kicp-workshops.uchicago.edu/IDM2012/ PARALLEL SESSIONS http://kicp.uchicago.edu/ http://www.nsf.gov/ http://www.uchicago.edu/ http://www.fnal.gov/ International Advisory Committee Daniel Akerib Elena Aprile Rita Bernabei Case Western Reserve University, Columbia University, USA Universita degli Studi di Roma, Italy Cleveland, USA Gianfranco Bertone Joakim Edsjo Katherine Freese University of Amsterdam Oskar Klein Centre / Stockholm University of Michigan, USA University Richard Gaitskell Gilles Gerbier Anne Green Brown University, USA IRFU/ CEA Saclay, France University of Nottingham, UK Karsten Jedamzik Xiangdong Ji Lawrence Krauss Universite de Montpellier, France University of Maryland, USA Arizona State University, USA Vitaly Kudryavtsev Reina Maruyama Leszek Roszkowski University of Sheffield University of Wisconsin-Madison University of Sheffield, UK Bernard Sadoulet Pierre Salati Daniel Santos University of California, Berkeley, USA University of California, Berkeley, USA LPSC/UJF/CNRS Pierre Sikivie Daniel Snowden-Ifft Neil Spooner University of Florida, USA Occidental College University of Sheffield, UK Max Tegmark Karl van Bibber Kavli Institute for Astrophysics & Space Naval Postgraduate School Monterey, Research at MIT, USA USA Local Organizing Committee Daniel Bauer Matthew Buckley Juan Collar Fermi National Accelerator Laboratory Fermi National Accelerator Laboratory Kavli Institute for Cosmological Physics Scott Dodelson Aimee
    [Show full text]
  • THE COSMIC COCKTAIL Three Parts Dark Matter
    release For immediate release Contact: Andrew DeSio Publication Date: June 11, 2014 (609) 258-5165 [email protected] Weaving a tale of scientific discovery, adventures in cosmology, and the hunt for dark matter, Dr. Katherine Freese explores just what exactly the universe is made out of in THE COSMIC COCKTAIL Three Parts Dark Matter “Freese tells her trailblazing and very personal story of how the worlds of particle physics and astronomy have come together to unveil the mysterious ingredients of the cosmic cocktail that we call our universe.” Brian Schmidt, 2011 Nobel Laureate in Physics, Australian National University What is dark matter? Where is it? Where did it come from? How do scientists study the stuff when they can’t see it? According to current research, our universe consists of only 5% ordinary matter (planets, comets, galaxies) while the rest is made of dark matter (26%) and dark energy (69%). Scientists and researchers are hard at work trying to detect these mysterious phenomena. And there are none further ahead in the pursuit than Dr. Katherine Freese, one of today’s foremost pioneers in the study of dark matter. In her splendidly written new book THE COSMIC COCKTAIL: Three Parts Dark Matter (Publication Date: June 11, 2014; $29.95), Dr. Freese tells the inside story of the epic quest to solve one of the most compelling enigmas of modern science—what is the universe made of? Blending cutting-edge science with her own behind-the-scenes insights as a leading researcher in the field, acclaimed theoretical physicist Katherine Freese recounts the hunt for dark matter, from the predictions and discoveries of visionary scientists like Fritz Zwicky— the Swiss astronomer who coined the term "dark matter" in 1933—to the deluge of data today from underground laboratories, satellites in space, and the Large Hadron Collider.
    [Show full text]
  • Some Aspects in Cosmological Perturbation Theory and F (R) Gravity
    Some Aspects in Cosmological Perturbation Theory and f (R) Gravity Dissertation zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn von Leonardo Castañeda C aus Tabio,Cundinamarca,Kolumbien Bonn, 2016 Dieser Forschungsbericht wurde als Dissertation von der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Bonn angenommen und ist auf dem Hochschulschriftenserver der ULB Bonn http://hss.ulb.uni-bonn.de/diss_online elektronisch publiziert. 1. Gutachter: Prof. Dr. Peter Schneider 2. Gutachter: Prof. Dr. Cristiano Porciani Tag der Promotion: 31.08.2016 Erscheinungsjahr: 2016 In memoriam: My father Ruperto and my sister Cecilia Abstract General Relativity, the currently accepted theory of gravity, has not been thoroughly tested on very large scales. Therefore, alternative or extended models provide a viable alternative to Einstein’s theory. In this thesis I present the results of my research projects together with the Grupo de Gravitación y Cosmología at Universidad Nacional de Colombia; such projects were motivated by my time at Bonn University. In the first part, we address the topics related with the metric f (R) gravity, including the study of the boundary term for the action in this theory. The Geodesic Deviation Equation (GDE) in metric f (R) gravity is also studied. Finally, the results are applied to the Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime metric and some perspectives on use the of GDE as a cosmological tool are com- mented. The second part discusses a proposal of using second order cosmological perturbation theory to explore the evolution of cosmic magnetic fields. The main result is a dynamo-like cosmological equation for the evolution of the magnetic fields.
    [Show full text]
  • Open Sloan-Dissertation.Pdf
    The Pennsylvania State University The Graduate School LOOP QUANTUM COSMOLOGY AND THE EARLY UNIVERSE A Dissertation in Physics by David Sloan c 2010 David Sloan Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2010 The thesis of David Sloan was reviewed and approved∗ by the following: Abhay Ashtekar Eberly Professor of Physics Dissertation Advisor, Chair of Committee Martin Bojowald Professor of Physics Tyce De Young Professor of Physics Nigel Higson Professor of Mathematics Jayanth Banavar Professor of Physics Head of the Department of Physics ∗Signatures are on file in the Graduate School. Abstract In this dissertation we explore two issues relating to Loop Quantum Cosmology (LQC) and the early universe. The first is expressing the Belinkskii, Khalatnikov and Lifshitz (BKL) conjecture in a manner suitable for loop quantization. The BKL conjecture says that on approach to space-like singularities in general rela- tivity, time derivatives dominate over spatial derivatives so that the dynamics at any spatial point is well captured by a set of coupled ordinary differential equa- tions. A large body of numerical and analytical evidence has accumulated in favor of these ideas, mostly using a framework adapted to the partial differential equa- tions that result from analyzing Einstein's equations. By contrast we begin with a Hamiltonian framework so that we can provide a formulation of this conjecture in terms of variables that are tailored to non-perturbative quantization. We explore this system in some detail, establishing the role of `Mixmaster' dynamics and the nature of the resulting singularity. Our formulation serves as a first step in the analysis of the fate of generic space-like singularities in loop quantum gravity.
    [Show full text]
  • The Cosmological Constant Einstein’S Static Universe
    Some History TEXTBOOKS FOR FURTHER REFERENCE 1) Physical Foundations of Cosmology, Viatcheslav Mukhanov 2) Cosmology, Michael Rowan-Robinson 3) A short course in General Relativity, J. Foster and J.D. Nightingale DERIVATION OF FRIEDMANN EQUATIONS IN A NEWTONIAN COSMOLOGY THE COSMOLOGICAL PRINCIPAL Viewed on a sufficiently large scale, the properties of the Universe are the same for all observers. This amounts to the strongly philosophical statement that the part of the Universe which we can see is a fair sample, and that the same physical laws apply throughout. => the Hubble expansion is a natural property of an expanding universe which obeys the cosmological principle Distribution of galaxies on the sky Distribution of 2.7 K microwave radiation on the sky vA = H0. rA vB = H0. rB v and r are position and velocity vectors VBA = VB – VA = H0.rB – H0.rA = H0 (rB - rA) The observer on galaxy A sees all other galaxies in the universe receding with velocities described by the same Hubble law as on Earth. In fact, the Hubble law is the unique expansion law compatible with homogeneity and isotropy. Co-moving coordinates: express the distance r as a product of the co-moving distance x and a term a(t) which is a function of time only: rBA = a(t) . x BA The original r coordinate system is known as physical coordinates. Deriving an equation for the universal expansion thus reduces to determining a function which describes a(t) Newton's Shell Theorem The force acting on A, B, C, D— which are particles located on the surface of a sphere of radius r—is the gravitational attraction from the matter internal to r only, acting as a point mass at O.
    [Show full text]
  • The Dark Energy of the Universe the Dark Energy of the Universe
    The Dark Energy of the Universe The Dark Energy of the Universe Jim Cline, McGill University Niels Bohr Institute, 13 Oct., 2015 image: bornscientist.com J.Cline, McGill U. – p. 1 Dark Energy in a nutshell In 1998, astronomers presented evidence that the primary energy density of the universe is not from particles or radiation, but of empty space—the vacuum. Einstein had predicted it 80 years earlier, but few people believed this prediction, not even Einstein himself. Many scientists were surprised, and the discovery was considered revolutionary. Since then, thousands of papers have been written on the subject, many speculating on the detailed properties of the dark energy. The fundamental origin of dark energy is the subject of intense controversy and debate amongst theorists. J.Cline, McGill U. – p. 2 Outline Part I History of the dark energy • Theory of cosmological expansion • The observational evidence for dark energy • Part II What could it be? • Upcoming observations • The theoretical crisis !!! • J.Cline, McGill U. – p. 3 Albert Einstein invents dark energy, 1917 Two years after introducing general relativity (1915), Einstein looks for cosmological solutions of his equations. No static solution exists, contrary to observed universe at that time He adds new term to his equations to allow for static universe, the cosmological constant λ: J.Cline, McGill U. – p. 4 Einstein’s static universe This universe is a three-sphere with radius R and uniform mass density of stars ρ (mass per volume). mechanical analogy potential energy R R By demanding special relationships between λ, ρ and R, λ = κρ/2 = 1/R2, a static solution can be found.
    [Show full text]
  • Conference Program
    Identification of Dark Matter July 23-27, 2012 9th International Conference Chicago, IL http://kicp-workshops.uchicago.edu/IDM2012/ CONFERENCE PROGRAM http://kicp.uchicago.edu/ http://www.nsf.gov/ http://www.uchicago.edu/ http://www.fnal.gov/ International Advisory Committee Daniel Akerib Elena Aprile Rita Bernabei Case Western Reserve University, Columbia University, USA Universita degli Studi di Roma, Italy Cleveland, USA Gianfranco Bertone Joakim Edsjo Katherine Freese University of Amsterdam Oskar Klein Centre / Stockholm University of Michigan, USA University Richard Gaitskell Gilles Gerbier Anne Green Brown University, USA IRFU/ CEA Saclay, France University of Nottingham, UK Karsten Jedamzik Xiangdong Ji Lawrence Krauss Universite de Montpellier, France University of Maryland, USA Arizona State University, USA Vitaly Kudryavtsev Reina Maruyama Leszek Roszkowski University of Sheffield University of Wisconsin-Madison University of Sheffield, UK Bernard Sadoulet Pierre Salati Daniel Santos University of California, Berkeley, USA University of California, Berkeley, USA LPSC/UJF/CNRS Pierre Sikivie Daniel Snowden-Ifft Neil Spooner University of Florida, USA Occidental College University of Sheffield, UK Max Tegmark Karl van Bibber Kavli Institute for Astrophysics & Space Naval Postgraduate School Monterey, Research at MIT, USA USA Local Organizing Committee Daniel Bauer Matthew Buckley Juan Collar Fermi National Accelerator Laboratory Fermi National Accelerator Laboratory Kavli Institute for Cosmological Physics Scott Dodelson Aimee
    [Show full text]
  • 3.1 the Robertson-Walker Metric
    M. Pettini: Introduction to Cosmology | Lecture 3 RELATIVISTIC COSMOLOGY 3.1 The Robertson-Walker Metric The appearance of objects at cosmological distances is affected by the curvature of spacetime through which light travels on its way to Earth. The most complete description of the geometrical properties of the Universe is provided by Einstein's general theory of relativity. In GR, the fundamental quantity is the metric which describes the geometry of spacetime. Let's look at the definition of a metric: in 3-D space we measure the distance along a curved path P between two points using the differential distance formula, or metric: (d`)2 = (dx)2 + (dy)2 + (dz)2 (3.1) and integrating along the path P (a line integral) to calculate the total distance: Z 2 q Z 2 q ∆` = (d`)2 = (dx)2 + (dy)2 + (dz)2 (3.2) 1 1 Similarly, to measure the interval along a curved wordline, W, connecting two events in spacetime with no mass present, we use the metric for flat spacetime: (ds)2 = (cdt)2 − (dx)2 − (dy)2 − (dz)2 (3.3) Integrating ds gives the total interval along the worldline W: Z B q Z B q ∆s = (ds)2 = (cdt)2 − (dx)2 − (dy)2 − (dz)2 (3.4) A A By definition, the distance measured between two events, A and B, in a reference frame for which they occur simultaneously (tA = tB) is the proper distance: q ∆L = −(∆s)2 (3.5) Our search for a metric that describes the spacetime of a matter-filled universe, is made easier by the cosmological principle.
    [Show full text]
  • Matthew Robert Buckley
    Matthew Robert Buckley Rutgers, The State University of New Jersey Cell: 626 379 4337 Department of Physics & Astronomy E-mail: [email protected] 136 Frelinghuysen Rd, Piscataway, NJ 08854 [email protected] Citizenship United States of America Education • 2003-2008 University of California, Berkeley Ph.D. Theoretical Particle Physics (received May 2008) Advisor: Professor Hitoshi Murayama M.A. Physics (received May 2005) • 1999-2003 Kenyon College B.A. summa cum laude Mathematics and Physics (received May 2003) Work Experience • September 2013-Present Assistant Research Professor, Rutgers, The State University of New Jersey • August 2010-August 2013 David N. Schramm Fellow, Fermi National Accel- erator Laboratory • September 2008-August 2010 Du Bridge Postdoctoral Scholar, Prize Fellow, California Institute of Technology • January-May 2008 Foreign Researcher, Institute of Physics and Mathematics of the Universe, Tokyo University • 2006-2008 Graduate Student Researcher with Hitoshi Murayama, University of California, Berkeley • 2003-2006 Graduate Student Instructor, University of California, Berkeley 1 Fellowships and Awards • 2010 David N. Schramm Fellow, Fermi National Accelerator Laboratory • 2008 Prize Fellowship, California Institute of Technology • 2004 Outstanding Graduate Student Instructor Award, University of California, Berkeley • 2002 Phi Beta Kappa, Kenyon College • 2002 Franklin Miller Award for Undergraduate Research, Kenyon College • 2001 Goldwater Scholar in Mathematics, Science and Engineering (Barry
    [Show full text]
  • Universes with a Cosmological Constant
    Universes with a cosmological constant Domingos Soares Physics Department Federal University of Minas Gerais Belo Horizonte, MG, Brasil July 21, 2015 Abstract I present some relativistic models of the universe that have the cos- mological constant (Λ) in their formulation. Einstein derived the first of them, inaugurating the theoretical strand of the application of the field equations of General Relativity with the cosmological constant. One of the models shown is the Standard Model of Cosmology, which presently enjoys the support of a significant share of the scientific community. 1 Introduction The first cosmological model based in General Relativity Theory (GRT) was put forward in 1917 by the creator of GRT himself. Einstein conceived the universe as a static structure and, to obtain the corresponding relativistic model, introduced a repulsive component in the formulation of the field equations of GRT to avoid the collapse produced by the matter. Such a component appears in the equations as an additional term of the metric field multiplied by a constant, the so-called cosmological constant (see [1, eq. 10]). The cosmological constant is commonly represented by the uppercase Greek letter (Λ) and has physical dimensions of 1/length2. Besides Einstein's static model, other relativistic models with the cos- mological constant were proposed. We will see that these models can be obtained from Friedmann's equation plus the cosmological constant, and by 1 means of the appropriate choices of the spatial curvature and of the matter- energy content of the universe. The cosmologist Steven Weinberg presents several of those models in his book Gravitation and Cosmology, in the chap- ter entitled Models with a Cosmological Constant [2, p.
    [Show full text]
  • Inelastic Dark Matter Scattering Off Thallium Cannot Save DAMA
    NORDITA-2020-123; UTTG-24-2020 Inelastic dark matter scattering off Thallium cannot save DAMA Sunniva Jacobsen,a Katherine Freese,a;b;c Chris Kelso,d Pearl Sandick,e Patrick Stengela;f;g;h aThe Oskar Klein Centre for Cosmoparticle Physics, Department of Physics, Stockholm University, AlbaNova, 10691 Stockholm, Sweden bNordita, KTH Royal Institute of Technology and Stockholm University Roslagstullsbacken 23, 10691 Stockholm, Sweden cDepartment of Physics, University of Texas, Austin, TX 78722 dDepartment of Physics, University of North Florida, Jacksonville, FL 32224, USA eDepartment of Physics and Astronomy, University of Utah, Salt Lake City, UT 84102, USA f Scuola Internazionale Superiore di Studi Avanzati (SISSA), via Bonomea 265, 34136 Trieste, Italy gINFN, Sezione di Trieste, via Valerio 2, 34127 Trieste, Italy hInstitute for Fundamental Physics of the Universe (IFPU), via Beirut 2, 34151 Trieste, Italy Abstract. We study the compatibility of the observed DAMA modulation signal with in- elastic scattering of dark matter (DM) off of the 0:1% Thallium (Tl) dopant in DAMA. In this work we test whether there exist regions of parameter space where the Tl interpretation gives a good fit to the most recent data from DAMA, and whether these regions are compati- ble with the latest constraints from other direct detection experiments. Previously, Chang et al. in 2010 [1], had proposed the Tl interpretation of the DAMA data, and more recently (in arXiv:2102.08367v2 [hep-ph] 17 Mar 2021 2019) the DAMA/LIBRA collaboration [2] found regions in parameter space of Tl inelastic scattering that differ by more than 10σ from a no modulation hypothesis.
    [Show full text]