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Dark Energy and Dark Matter As Inertial Effects Introduction
Dark Energy and Dark Matter as Inertial Effects Serkan Zorba Department of Physics and Astronomy, Whittier College 13406 Philadelphia Street, Whittier, CA 90608 [email protected] ABSTRACT A disk-shaped universe (encompassing the observable universe) rotating globally with an angular speed equal to the Hubble constant is postulated. It is shown that dark energy and dark matter are cosmic inertial effects resulting from such a cosmic rotation, corresponding to centrifugal (dark energy), and a combination of centrifugal and the Coriolis forces (dark matter), respectively. The physics and the cosmological and galactic parameters obtained from the model closely match those attributed to dark energy and dark matter in the standard Λ-CDM model. 20 Oct 2012 Oct 20 ph] - PACS: 95.36.+x, 95.35.+d, 98.80.-k, 04.20.Cv [physics.gen Introduction The two most outstanding unsolved problems of modern cosmology today are the problems of dark energy and dark matter. Together these two problems imply that about a whopping 96% of the energy content of the universe is simply unaccounted for within the reigning paradigm of modern cosmology. arXiv:1210.3021 The dark energy problem has been around only for about two decades, while the dark matter problem has gone unsolved for about 90 years. Various ideas have been put forward, including some fantastic ones such as the presence of ghostly fields and particles. Some ideas even suggest the breakdown of the standard Newton-Einstein gravity for the relevant scales. Although some progress has been made, particularly in the area of dark matter with the nonstandard gravity theories, the problems still stand unresolved. -
Dark Energy and Dark Matter
Dark Energy and Dark Matter Jeevan Regmi Department of Physics, Prithvi Narayan Campus, Pokhara [email protected] Abstract: The new discoveries and evidences in the field of astrophysics have explored new area of discussion each day. It provides an inspiration for the search of new laws and symmetries in nature. One of the interesting issues of the decade is the accelerating universe. Though much is known about universe, still a lot of mysteries are present about it. The new concepts of dark energy and dark matter are being explained to answer the mysterious facts. However it unfolds the rays of hope for solving the various properties and dimensions of space. Keywords: dark energy, dark matter, accelerating universe, space-time curvature, cosmological constant, gravitational lensing. 1. INTRODUCTION observations. Precision measurements of the cosmic It was Albert Einstein first to realize that empty microwave background (CMB) have shown that the space is not 'nothing'. Space has amazing properties. total energy density of the universe is very near the Many of which are just beginning to be understood. critical density needed to make the universe flat The first property that Einstein discovered is that it is (i.e. the curvature of space-time, defined in General possible for more space to come into existence. And Relativity, goes to zero on large scales). Since energy his cosmological constant makes a prediction that is equivalent to mass (Special Relativity: E = mc2), empty space can possess its own energy. Theorists this is usually expressed in terms of a critical mass still don't have correct explanation for this but they density needed to make the universe flat. -
Can an Axion Be the Dark Energy Particle?
Kuwait53 J. Sci.Can 45 an(3) axion pp 53-56, be the 2018 dark energy particle? Can an axion be the dark energy particle? Elias C. Vagenas Theoretical Physics Group, Department of Physics Kuwait University, P.O. Box 5969, Safat 13060, Kuwait [email protected] Abstract Following a phenomenological analysis done by the late Martin Perl for the detection of the dark energy, we show that an axion of energy can be a viable candidate for the dark energy particle. In particular, we obtain the characteristic length and frequency of the axion as a quantum particle. Then, employing a relation that connects the energy density with the frequency of a particle, i.e., , we show that the energy density of axions, with the aforesaid value of mass, as obtained from our theoretical analysis is proportional to the dark energy density computed on observational data, i.e., . Keywords: Axion, axion-like particles, dark energy, dark energy particle 1. Introduction Therefore, though the energy density of the electric field, i.e., One of the most important and still unsolved problem in , can be detected and measured, the dark energy density, contemporary physics is related to the energy content of the i.e., , which is much larger has not been detected yet. universe. According to the recent results of the 2015 Planck Of course, one has to avoid to make an experiment for the mission (Ade et al., 2016), the universe roughly consists of detection and measurement of the dark energy near the 69.11% dark energy, 26.03% dark matter, and 4.86% baryonic surface of the Earth, or the Sun, or the planets, since the (ordinary) matter. -
Dark Energy and CMB
Dark Energy and CMB Conveners: S. Dodelson and K. Honscheid Topical Conveners: K. Abazajian, J. Carlstrom, D. Huterer, B. Jain, A. Kim, D. Kirkby, A. Lee, N. Padmanabhan, J. Rhodes, D. Weinberg Abstract The American Physical Society's Division of Particles and Fields initiated a long-term planning exercise over 2012-13, with the goal of developing the community's long term aspirations. The sub-group \Dark Energy and CMB" prepared a series of papers explaining and highlighting the physics that will be studied with large galaxy surveys and cosmic microwave background experiments. This paper summarizes the findings of the other papers, all of which have been submitted jointly to the arXiv. arXiv:1309.5386v2 [astro-ph.CO] 24 Sep 2013 2 1 Cosmology and New Physics Maps of the Universe when it was 400,000 years old from observations of the cosmic microwave background and over the last ten billion years from galaxy surveys point to a compelling cosmological model. This model requires a very early epoch of accelerated expansion, inflation, during which the seeds of structure were planted via quantum mechanical fluctuations. These seeds began to grow via gravitational instability during the epoch in which dark matter dominated the energy density of the universe, transforming small perturbations laid down during inflation into nonlinear structures such as million light-year sized clusters, galaxies, stars, planets, and people. Over the past few billion years, we have entered a new phase, during which the expansion of the Universe is accelerating presumably driven by yet another substance, dark energy. Cosmologists have historically turned to fundamental physics to understand the early Universe, successfully explaining phenomena as diverse as the formation of the light elements, the process of electron-positron annihilation, and the production of cosmic neutrinos. -
Modified Newtonian Dynamics
Faculty of Mathematics and Natural Sciences Bachelor Thesis University of Groningen Modified Newtonian Dynamics (MOND) and a Possible Microscopic Description Author: Supervisor: L.M. Mooiweer prof. dr. E. Pallante Abstract Nowadays, the mass discrepancy in the universe is often interpreted within the paradigm of Cold Dark Matter (CDM) while other possibilities are not excluded. The main idea of this thesis is to develop a better theoretical understanding of the hidden mass problem within the paradigm of Modified Newtonian Dynamics (MOND). Several phenomenological aspects of MOND will be discussed and we will consider a possible microscopic description based on quantum statistics on the holographic screen which can reproduce the MOND phenomenology. July 10, 2015 Contents 1 Introduction 3 1.1 The Problem of the Hidden Mass . .3 2 Modified Newtonian Dynamics6 2.1 The Acceleration Constant a0 .................................7 2.2 MOND Phenomenology . .8 2.2.1 The Tully-Fischer and Jackson-Faber relation . .9 2.2.2 The external field effect . 10 2.3 The Non-Relativistic Field Formulation . 11 2.3.1 Conservation of energy . 11 2.3.2 A quadratic Lagrangian formalism (AQUAL) . 12 2.4 The Relativistic Field Formulation . 13 2.5 MOND Difficulties . 13 3 A Possible Microscopic Description of MOND 16 3.1 The Holographic Principle . 16 3.2 Emergent Gravity as an Entropic Force . 16 3.2.1 The connection between the bulk and the surface . 18 3.3 Quantum Statistical Description on the Holographic Screen . 19 3.3.1 Two dimensional quantum gases . 19 3.3.2 The connection with the deep MOND limit . -
Dark Energy – Much Ado About Nothing
Dark Energy – Much Ado About Nothing If you are reading this, then very possibly you have heard that Dark Energy makes up roughly three-fourths of the Universe, and you are curious about that. You may have seen the Official NASA Pie Chart that shows what the Universe is made of (at right). You may have heard Tyson deGrasse expounding about it on PBS. And there is no question that the term “Dark Energy” does refer to something. However, from the layman’s point of view, there are two small problems with understanding Dark Energy when you call it Dark Energy: (1) It’s not dark. (2) It’s not energy. Dark Energy is the winner of my personal award for the most misleading physics jargon of the 21st Century. This monument to misdirection was generated because it sounded cool, not because it is even close to being accurate. The jargon term Dark Matter already existed – and does, by the way, refer to something real – and rather than giving a descriptive name to their theoretical musings, the theoreticians decided, why not use a cute parallel name to Dark Matter? Why not create the buzz term Dark Energy? To which I say, like wow, man. That name is so – hip. Unfortunately, it is also nearly meaningless. Thus, the first thing we must do is get it straight: Dark Energy does not exist. Calling it an energy implies that the Dark Energy is, well, an energy – and it isn’t. It cannot be turned into heat, or electricity, or anything else that you and I would normally identify as energy. -
Dark Energy Survey Year 3 Results: Multi-Probe Modeling Strategy and Validation
DES-2020-0554 FERMILAB-PUB-21-240-AE Dark Energy Survey Year 3 Results: Multi-Probe Modeling Strategy and Validation E. Krause,1, ∗ X. Fang,1 S. Pandey,2 L. F. Secco,2, 3 O. Alves,4, 5, 6 H. Huang,7 J. Blazek,8, 9 J. Prat,10, 3 J. Zuntz,11 T. F. Eifler,1 N. MacCrann,12 J. DeRose,13 M. Crocce,14, 15 A. Porredon,16, 17 B. Jain,2 M. A. Troxel,18 S. Dodelson,19, 20 D. Huterer,4 A. R. Liddle,11, 21, 22 C. D. Leonard,23 A. Amon,24 A. Chen,4 J. Elvin-Poole,16, 17 A. Fert´e,25 J. Muir,24 Y. Park,26 S. Samuroff,19 A. Brandao-Souza,27, 6 N. Weaverdyck,4 G. Zacharegkas,3 R. Rosenfeld,28, 6 A. Campos,19 P. Chintalapati,29 A. Choi,16 E. Di Valentino,30 C. Doux,2 K. Herner,29 P. Lemos,31, 32 J. Mena-Fern´andez,33 Y. Omori,10, 3, 24 M. Paterno,29 M. Rodriguez-Monroy,33 P. Rogozenski,7 R. P. Rollins,30 A. Troja,28, 6 I. Tutusaus,14, 15 R. H. Wechsler,34, 24, 35 T. M. C. Abbott,36 M. Aguena,6 S. Allam,29 F. Andrade-Oliveira,5, 6 J. Annis,29 D. Bacon,37 E. Baxter,38 K. Bechtol,39 G. M. Bernstein,2 D. Brooks,31 E. Buckley-Geer,10, 29 D. L. Burke,24, 35 A. Carnero Rosell,40, 6, 41 M. Carrasco Kind,42, 43 J. Carretero,44 F. J. Castander,14, 15 R. -
TECHNICAL ASPECTS of ILLUSTRIS- a COSMOLOGICAL SIMULATION Dr Sheshappa SN1, Megha S Kencha Reddy2 , N Chandana3
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 07 Issue: 05 | May 2020 www.irjet.net p-ISSN: 2395-0072 TECHNICAL ASPECTS OF ILLUSTRIS- A COSMOLOGICAL SIMULATION Dr Sheshappa SN1, Megha S Kencha Reddy2 , N Chandana3, Ranjitha N4, Sushma Fouzdar5 1Faculty, Dept. of ISE, Sir MVIT, Karnataka, India, [email protected], 2VIII semester, Dept. of ISE, Sir MVIT ---------------------------------------------------------------------------***--------------------------------------------------------------------------- Abstract - THE BIG QUESTION - Where did we come galaxy formation. Recent simulations follow the from and where are we going?Humans have been trying formation of individual galaxies and galaxy populations to figure out the origin of the known universe since the from well-defined initial conditions and yield realistic beginning of time and Since the early part of the 1900s, galaxy properties. At the core of these simulations are the Big Bang theory is the most accepted explanation and detailed galaxy formation models. Of the many aspects has dominated the discussion of the origin and fate of the these models are capable of, they describe the cooling of universe. And the future of the universe can only be gas, the formation of stars, and the energy and hypothesized based on our knowledge but the question momentum injection caused by supermassive black does not seem to get irrelevant anytime in the near holes and massive stars. Nowadays, simulations also future. With the advancement technology and the model the impact of radiation fields, relativistic particles available research, data and techniques like data mining and magnetic fields, leading to an increasingly complex and machine learning the problems can be visualised description of the galactic ecosystem and the detailed through accurate digital representations and simulations evolution of galaxies in the cosmological context. -
Bulk Viscosity As an Alternative to Dark Energy
Prepared for submission to JCAP CERN-PH-TH/2011-156, LAPTH-023/11 Dark goo: Bulk viscosity as an alternative to dark energy Jean-Sebastien Gagnon,a Julien Lesgourguesb aTechnische Universit¨at Darmstadt, Schlossgartenstrasse 2, 64289, Darmstadt, Germany bEcole´ Polytechnique F´ed´erale de Lausanne, CH-1015, Lausanne, Switzerland; CERN, Theory Division, CH-1211 Geneva 23, Switzerland; LAPTh (CNRS - Universit´ede Savoie), BP 110, F-74941 Annecy-le-Vieux Cedex, France. E-mail: [email protected], [email protected] Abstract. We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an “effective” pressure containing the bulk viscosity. For a sufficiently large bulk viscosity, the effective pressure becomes negative and could mimic a dark energy equation of state. Our microscopic model includes self-interacting spin-zero particles (for which the bulk viscosity is known) that are added to the usual energy content of the universe. We study both background equations and linear perturbations in this model. We show that a dark energy behavior is obtained for reasonable values of the two parameters of the model (i.e. the mass and coupling of the spin-zero particles) and that linear perturbations are well-behaved. There is no apparent fine tuning involved. We also discuss the conditions under which hydrodynamics holds, in particular that the spin-zero particles -
The Next Generation of Hydrodynamical Simulations of Galaxy Formation
HLRS Golden Spike Award 2016 The Next Generation of Hydrodynamical Simulations of Galaxy Formation Scientific background galaxies in clusters and the characteristics of Galaxies are comprised of up to several hundred hydrogen on large scales, and at the same time billion stars and display a variety of shapes and matched the metal and hydrogen content of sizes. Their formation involves a complicated galaxies on small scales. Indeed, the virtual uni- blend of astrophysics, including gravitational, verse created by Illustris resembles the real one hydrodynamical and radiative processes, as well so closely that it can be adopted as a powerful as dynamics in the enigmatic „dark sector“ of laboratory to further explore and characterize the Universe, which is composed of dark mat- galaxy formation physics. This is underscored ter and dark energy. Dark matter is thought to by the nearly 100 publications that have been consist of a yet unidentified elementary parti- written using the simulation thus far. cle, making up about 85% of all matter, whereas dark energy opposes gravity and has induced However, the Illustris simulation also showed an accelerated expansion of the Universe in the some tensions between its predictions and recent past. Because the governing equations observations of the real Universe, calling for both, are too complicated to be solved analytically, improvements in the physical model as well as numerical simulations have become a primary in the numerical accuracy and size of the simu- tool in theoretical astrophysics to study cosmic lations used to represent the cosmos. For exam- structure formation. Such calculations connect ple, one important physical ingredient that was the comparatively simple initial state left behind missing are magnetic fields. -
Arxiv:2010.00693V2 [Astro-Ph.GA] 31 Oct 2020 Total Mass of Dark Matter Around Galaxies
Draft version November 3, 2020 Typeset using LATEX twocolumn style in AASTeX63 Tracing Dark Matter Halos with Satellite Kinematics and the Central Stellar Velocity Dispersion of Galaxies Gangil Seo1, Jubee Sohn2, Myung Gyooon Lee1;∗1, 2 11 Astronomy Program, Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 151-742, Republic of Korea 22 Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA ABSTRACT It has been suggested that the central stellar velocity dispersion of galaxies can trace dark matter halo mass directly. We test this hypothesis using a complete spectroscopic sample of isolated galaxies surrounded by faint satellite galaxies from the Sloan Digital Sky Survey Data Release 12. We apply a friends-of-friends algorithm with projected linking length ∆D < 100 kpc and radial velocity linking length ∆V < 1000 km s−1 to construct our sample. Our sample includes 2807 isolated galaxies with 3417 satellite galaxies at 0:01 < z < 0:14. We divide the sample into two groups based on the primary galaxy color: red and blue primary galaxies separated at (g − r)0 = 0:85. The central stellar velocity dispersions of the primary galaxies are proportional to the luminosities and stellar masses of the same galaxies. Stacking the sample based on the central velocity dispersion of the primary galaxies, we derive the velocity dispersions of their satellite galaxies, which trace the dark matter halo mass of the primary galaxies. The system velocity dispersion of the satellite galaxies shows a remarkably tight correlation with the central velocity dispersion of the primary galaxies for both red and blue samples. -
The Diversity and Variability of Star Formation Histories in Different Simulations
Draft version September 14, 2018 Typeset using LATEX twocolumn style in AASTeX61 THE DIVERSITY AND VARIABILITY OF STAR FORMATION HISTORIES IN DIFFERENT SIMULATIONS Kartheik Iyer, Sandro Tacchella, Lars Hernquist, Shy Genel, Chris Hayward, Neven Caplar, Phil Hopkins, Rachel Somerville, Romeel Dave, Ena Choi, and Viraj Pandya ABSTRACT As observational constraints on the star formation histories of galaxies improve due to higher S/N data and sophis- ticated analysis techniques, we have a better understanding of how galaxy scaling relations, such as the stellar mass star-formation rate and mass metallicity relations, evolve over the last 10 billion years. Despite these constraints, we have still a poor understanding of how individual galaxies evolve in these parameter spaces and therefore the physical processes that govern these scaling relations. We compile SFHs from an extensive set of simulations at z = 0 and z = 1, ranging from cosmological hydrodynamical simulations (Illustris, IllustrisTNG, MUFASA, SIMBA), zoom-in simula- tions (FIRE-2, VELA, Choi+17), semi-analytic models (Santa-Cruz SAM) and empirical models (UniverseMachine) to investigate the timescales on which star formation rates vary in different models. We quantify the diversity in SFHs from different simulations using the Hurst index and use a random forest based analysis to quantify the factors that drive this diversity. We then use a power spectral density based analysis to quantify the SFH variability as a function of the different timescales on which different physical processes act. This allows us to assess the impact of different (stellar / black hole) feedback processes, which affect the star formation on short timescales, versus gas accretion physics, which affect the star formation on longer timescales.