DOCSLIB.ORG

Pt Symmetry, Quantum Gravity, and the Metrication of the Fundamental Forces Philip D. Mannheim Department of Physics University

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Pt Symmetry, Quantum Gravity, and the Metrication of the Fundamental Forces Philip D. Mannheim Department of Physics University PT SYMMETRY, QUANTUM GRAVITY, AND THE METRICATION OF THE FUNDAMENTAL FORCES PHILIP D. MANNHEIM DEPARTMENT OF PHYSICS UNIVERSITY OF CONNECTICUT PRESENTATION AT MIAMI 2014 FORT LAUDERDALE FLORIDA, DECEMBER 2014 1 UBIQUITY OF PT SYMMETRY 1. PT SYMMETRY AS A DYNAMICS 2. HIDDEN SECRET OF PT SYMMETRY{UNITARITY/NO GHOSTS 3. PT SYMMETRY AND THE LORENTZ GROUP 4. PT SYMMETRY AND THE CONFORMAL GROUP 5. PT SYMMETRY AND GRAVITY 6. PT SYMMETRY AND GEOMETRY 7. PT SYMMETRY AND THE DIRAC ACTION i 8. PT SYMMETRY AND THE METRICATION OF Aµ AND Aµ 9. THE UNEXPECTED PT SURPRISE 10. ASTROPHYSICAL EVIDENCE FOR THE PT REALIZATION OF CONFORMAL GRAVITY 2 GHOST PROBLEMS, UNITARITY OF FOURTH-ORDER THEORIES AND PT QUANTUM MECHANICS 1. P. D. Mannheim and A. Davidson, Fourth order theories without ghosts, January 2000 (arXiv:0001115 [hep-th]). 2. P. D. Mannheim and A. Davidson, Dirac quantization of the Pais-Uhlenbeck fourth order oscillator, Phys. Rev. A 71, 042110 (2005). (0408104 [hep-th]). 3. P. D. Mannheim, Solution to the ghost problem in fourth order derivative theories, Found. Phys. 37, 532 (2007). (arXiv:0608154 [hep-th]). 4. C. M. Bender and P. D. Mannheim, No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck oscillator model, Phys. Rev. Lett. 100, 110402 (2008). (arXiv:0706.0207 [hep-th]). 5. C. M. Bender and P. D. Mannheim, Giving up the ghost, Jour. Phys. A 41, 304018 (2008). (arXiv:0807.2607 [hep-th]) 6. C. M. Bender and P. D. Mannheim, Exactly solvable PT-symmetric Hamiltonian having no Hermitian counterpart, Phys. Rev. D 78, 025022 (2008). (arXiv:0804.4190 [hep-th]) 7. C. M. Bender and P. D. Mannheim, PT symmetry and necessary and sufficient conditions for the reality of energy eigenvalues, Phys. Lett. A 374, 1616 (2010). (arXiv:0902.1365 [hep-th]) 8. P. D. Mannheim, PT symmetry as a necessary and sufficient condition for unitary time evolution, Phil. Trans. Roy. Soc. A. (arXiv:0912.2635 [hep-th]) 9. C. M. Bender and P. D. Mannheim, PT symmetry in relativistic quantum mechanics, Phys. Rev. D 84, 105038 (2011). (arXiv:1107.0501 [hep-th]) CONFORMAL GRAVITY AND THE COSMOLOGICAL CONSTANT AND DARK MATTER PROBLEMS 10. P. D. Mannheim, Alternatives to dark matter and dark energy, Prog. Part. Nuc. Phys. 56, 340 (2006). (arXiv:0505266 [astro-ph]). 11. P. D. Mannheim, Why do we believe in dark matter and dark energy { and do we have to?, in "Questions of Modern Cosmology { Galileo's Legacy", M. D'Onofrio and C. Burigana (Eds.), Springer Publishing Company, Heidelberg (2009). 12. P. D. Mannheim, Conformal Gravity Challenges String Theory, Proceedings of the Second Crisis in Cosmology Conference, CCC-2, Astronomical Society of the Pacific Conference Series Vol. 413. (F. Potter, Ed.), San Francisco (2009). (arXiv:0707.2283 [hep-th]) 13. P. D. Mannheim, Dynamical symmetry breaking and the cosmological constant problem, Proceedings of ICHEP08, eConf C080730. (0809.1200 [hep-th]). 14. P. D. Mannheim, Comprehensive solution to the cosmological constant, zero-point energy, and quantum gravity problems, Gen. Rel. Gravit. 43, 703 (2011). (arXiv:0909.0212 [hep-th]) 15. P. D. Mannheim, Intrinsically quantum-mechanical gravity and the cosmological constant problem, Mod. Phys. Lett. A 26, 2375 (2011). (arXiv:1005.5108 [hep-th]). 16. P. D. Mannheim and J. G. O'Brien, Impact of a global quadratic potential on galactic rotation curves, Phys. Rev. Lett. 106, 121101 (2011). (arXiv:1007.0970 [astro-ph.CO]). 17. P. D. Mannheim and J. G. O'Brien, Fitting galactic rotation curves with conformal gravity and a global quadratic potential, Phys. Rev. D 85, 124020(2012). (arXiv:1011.3495 [astro-ph.CO]) 18. P. D. Mannheim, Making the case for conformal gravity, Found. Phys. 42, 388 (2012). (arXiv:1101.2186 [hep-th]). 19. J. G. O'Brien and P. D. Mannheim, Fitting dwarf galaxy rotation curves with conformal gravity. MNRAS 421, 1273 (2012). (arXiv:1107.5229 [astro-ph.CO]) 20. P. D. Mannheim, Cosmological perturbations in conformal gravity, Phys. Rev. D. 85, 124008 (2012). (arXiv:1109.4119 [gr-qc]) 21. P. D.Mannheim Astrophysical Evidence for the Non-Hermitian but PT -symmetric Hamiltonian of Conformal Gravity, Fortschritte der Physik - 61, 140 (2013). (arXiv:1205.5717 [hep-th]) 22. P. D. Mannheim and J. G. O'Brien, Galactic rotation curves in conformal gravity, J. Phys. Conf. Ser. 437, 012002 (2013). (arXiv:1211.0188 [astro-ph.CO]) 3 TORSION 1. L. Fabbri and P. D. Mannheim, Continuity of the torsionless limit as a selection rule for gravity theories with torsion, May 2014, Phys. Rev. D 90, 024042 (2014). (arXiv:1405.1248 [gr-qc]). 2. P. D. Mannheim and J. J. Poveromo, Gravitational Analog of Faraday's Law via Torsion and a Metric with an Anti- symmetric Part, General Relativity and Gravitation 46, 1795 (2014). (arXiv:1406.1470 [gr-qc]). 3. P. D. Mannheim, Torsion, Magnetic Monopoles and Faraday's Law via a Variational Principle, June 2014. (arXiv:1406.2265 [hep-th]). 4. P. D. Mannheim, PT Symmetry, Conformal Symmetry, and the Metrication of Electromagnetism, July 2014. (arXiv:1407.1820 [hep-th]). 4 1 PT SYMMETRY AS A DYNAMICS Pioneered by Bender (1998). HERMITICITY is only SUFFICIENT to secure reality of eigenvalues. PT SYMMETRY of a Hamiltonian is the NECESSARY condition. Instead of considering the eigenvector equation Hj i = Ej i, focus on the eigenvalue equation f(λ) = jH − λIj = 0 instead. Theorem: The condition [H; P T ] = 0 is both a SUFFICIENT (Bender, Berry and Mandilara (2002)) and NECESSARY (Bender and Mannheim (2010)) condition for the reality of f(λ). However three realizations: 1. All λi are real and set of all j ii is complete. H is then either already Hermitian or by a non-unitary similarity transform on the eigenvector basis can be brought to a basis in which ∗ Hij = Hji. Thus Hermitian in disguise. Example (Bender, Brody and Jones (2003)): r cos θ + ir sin θ s H = r cos θσ + ir sin θσ + sσ = =6 Hy: (1) 0 3 1 s r cos θ − ir sin θ Here P = σ1, T = K (complex conjugation) and [H; P T ] = 0. Energies E± = r cos θ ± (s2 − r2 sin2 θ)1=2. If s2 − r2 sin2 θ = s sin α is positive, both energies are real. 1 + sin α1=2 1 − sin α1=2 G±1 = σ ± σ ; GHG−1 = r cos θσ + σ (s2 − r2 sin2 θ)1=2 2 sin α 0 2 2 sin α 0 1 (2) 5 ∗ 2. λi come in complex conjugate pairs (T : E ! E ) and set of all j ii is complete. Thus have decaying states (loss) and growing states (gain), and need both (Mannheim (2013)) for unitarity { as the population of a state is depleted the population of its complex conjugate partner grows. Example: s2 − r2 sin2 θ is negative, energies in a complex conjugate pair. 3. The λi are all equal (and thus all real) but eigenvectors incomplete - Jordan block realization. Example: The above H with s2 − r2 sin2 θ = 0 (G no longer exists), or 1 1 M = =6 M y (3) 0 1 TWO real solutions to jM − λIj = 0, viz. λ1 = 1, λ2 = 1 (Trace = 2, Determinant =1). But only ONE eigenstate { 1 1 p p + q p 1 = = ; q = 0; (4) 0 1 q q q 0 Eigenvalues degenerate since they have to share just the one eigenvector. Missing eigenvectors are not stationary. Nonetheless theory is unitary (Bender and Mannheim (2008)) since stationary plus non-stationary states combined form a complete basis. SUMMARY: PT SYMMETRY OF A HAMILTONIAN IS A DIAGNOS- TIC FOR PROPERTIES OF ITS EIGENVALUES, AND IS A BOTH NEC- ESSARY AND SUFFICIENT CONDITION FOR UNITARITY. 6 2 HIDDEN SECRET OF PT SYMMETRY { UNITARITY/NO GHOSTS Once the Hamiltonian is not Hermitian one can no longer use the Dirac norm. Given a right eigenvector jRii of H, which obeys HjRii = EjRii, the Dirac norm hRi(t)jRi(t)i = −iHyt iHt hRi(t = 0)je e jRi(t = 0)i is not equal to hRi(t = 0)jRi(t = 0)i, with the Dirac norm not being preserved in time in the non-Hermitian case. However, if we instead introduce a left eigenvector, which obeys hLijH = hLijE, then the norm hLi(t)jRi(t)i = hLi(t = −iHt iHt 0)je e jRi(t = 0)i = hLi(t = 0)jRi(t = 0)i is preserved in time. With left eigenvectors being related to the PT conjugates of the right eigenvectors, in the non-Hermitian but PT symmetric case one should instead use the PT theory norm, with unitary time evolution then being secured. In those cases where the Dirac norm is found to be negative, this does not necessarily mean that there are ghost states in the theory, since when the theory can be reinterpreted as a PT theory, the PT theory norm would be positive { case (1) above , where the theory Hamiltonian is Hermitian in disguise, and thus necessarily ghost free, with scalar products not being able to change sign under a similarity transformation. 7 Two cases of this effect have been identified in the literature. The Lee model (Lee 1954), and the fourth-order Pais-Uhlenbeck oscillator (Pais and Uhlenbeck (1950)) with action, equation of motion and propagator of the form: γ Z I = dt[z¨2 − (!2 + !2)z_2 + !2!2z2]; PU 2 1 2 1 2 d4z d2z + (!2 + !2) + !2!2z = 0; dt4 1 2 dt2 1 2 1 1 1 1 G(E) = 2 2 2 2 = 2 2 2 2 − 2 2 : (5) (E − !1)(E − !2) !1 − !2 E − !1 E − !2 In both cases the Dirac norm is found to be negative, but both turn out to be non-Hermitian but PT theories, with their PT theory norms being positive.
Load more

Recommended publications
  • Galaxy Disks Annual Reviews Content Online, Including: 1 2 • Other Articles in This Volume P.C
    AA49CH09-vanderKruit ARI 5 August 2011 9:18 ANNUAL REVIEWS Further Click here for quick links to Galaxy Disks Annual Reviews content online, including: 1 2 • Other articles in this volume P.C. van der Kruit and K.C. Freeman • Top cited articles 1 • Top downloaded articles Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen, • Our comprehensive search The Netherlands; email: [email protected] 2Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, ACT 2611, Australia; email: [email protected] Annu. Rev. Astron. Astrophys. 2011. 49:301–71 Keywords The Annual Review of Astronomy and Astrophysics is disks in galaxies: abundance gradients, chemical evolution, disk stability, online at astro.annualreviews.org formation, luminosity distributions, mass distributions, S0 galaxies, scaling This article’s doi: laws, thick disks, surveys, warps and truncations 10.1146/annurev-astro-083109-153241 Copyright c 2011 by Annual Reviews. Abstract ! All rights reserved The disks of disk galaxies contain a substantial fraction of their baryonic mat- 0066-4146/11/0922-0301$20.00 ter and angular momentum, and much of the evolutionary activity in these galaxies, such as the formation of stars, spiral arms, bars and rings, and the various forms of secular evolution, takes place in their disks. The formation and evolution of galactic disks are therefore particularly important for under- standing how galaxies form and evolve and the cause of the variety in which they appear to us. Ongoing large surveys, made possible by new instrumen- tation at wavelengths from the UV (Galaxy Evolution Explorer), via optical (Hubble Space Telescope and large groundbased telescopes) and IR (Spitzer Space Telescope), to the radio are providing much new information about disk galaxies over a wide range of redshift.
    [Show full text]
  • Pt Symmetry, Quantum Gravity, and the Metrication of the Fundamental Forces Philip D. Mannheim Department of Physics University
    PT SYMMETRY, QUANTUM GRAVITY, AND THE METRICATION OF THE FUNDAMENTAL FORCES PHILIP D. MANNHEIM DEPARTMENT OF PHYSICS UNIVERSITY OF CONNECTICUT PRESENTATION AT DISCRETE 2014 KING'S COLLEGE LONDON, DECEMBER 2014 1 TOPICS TO BE DISCUSSED 1. PT SYMMETRY AS A DYNAMICS 2. HIDDEN SECRET OF PT SYMMETRY{UNITARITY/NO GHOSTS 3. PT SYMMETRY AND THE LORENTZ GROUP 4. PT SYMMETRY AND THE CONFORMAL GROUP 5. PT SYMMETRY AND GRAVITY 6. PT SYMMETRY AND GEOMETRY 7. PT SYMMETRY AND THE DIRAC ACTION i 8. PT SYMMETRY AND THE METRICATION OF Aµ AND Aµ 9. THE UNEXPECTED PT SURPRISE 10. ASTROPHYSICAL EVIDENCE FOR THE PT REALIZATION OF CONFORMAL GRAVITY 2 GHOST PROBLEMS, UNITARITY OF FOURTH-ORDER THEORIES AND PT QUANTUM MECHANICS 1. P. D. Mannheim and A. Davidson, Fourth order theories without ghosts, January 2000 (arXiv:0001115 [hep-th]). 2. P. D. Mannheim and A. Davidson, Dirac quantization of the Pais-Uhlenbeck fourth order oscillator, Phys. Rev. A 71, 042110 (2005). (0408104 [hep-th]). 3. P. D. Mannheim, Solution to the ghost problem in fourth order derivative theories, Found. Phys. 37, 532 (2007). (arXiv:0608154 [hep-th]). 4. C. M. Bender and P. D. Mannheim, No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck oscillator model, Phys. Rev. Lett. 100, 110402 (2008). (arXiv:0706.0207 [hep-th]). 5. C. M. Bender and P. D. Mannheim, Giving up the ghost, Jour. Phys. A 41, 304018 (2008). (arXiv:0807.2607 [hep-th]) 6. C. M. Bender and P. D. Mannheim, Exactly solvable PT-symmetric Hamiltonian having no Hermitian counterpart, Phys. Rev. D 78, 025022 (2008).
    [Show full text]
  • OBSERVATIONAL EVIDENCE for the NON-DIAGONALIZABLE HAMILTONIAN of CONFORMAL GRAVITY Philip D. Mannheim University of Connecticut
    OBSERVATIONAL EVIDENCE FOR THE NON-DIAGONALIZABLE HAMILTONIAN OF CONFORMAL GRAVITY Philip D. Mannheim University of Connecticut Seminar in Dresden June 2011 1 On January 19, 2000 a paper by P. D. Mannheim and A. Davidson,“Fourth order theories without ghosts” appeared on the arXiv as hep-th/0001115. The paper was later published as P. D. Mannheim and A. Davidson, “Dirac quantization of the Pais-Uhlenbeck fourth order oscillator”, Physical Review A 71, 042110 (2005). (hep-th/0408104). The abstract of the 2000 paper read: Using the Dirac constraint method we show that the pure fourth-order Pais-Uhlenbeck oscillator model is free of observable negative norm states. Even though such ghosts do appear when the fourth order theory is coupled to a second order one, the limit in which the second order action is switched off is found to be a highly singular one in which these states move off shell. Given this result, construction of a fully unitary, renormalizable, gravitational theory based on a purely fourth order action in 4 dimensions now appears feasible. Then in the 2000 paper it read: “We see that the complete spectrum of eigenstates of H(ǫ = 0) =8γω4(2b†b + a†b + b†a)+ ω is the set of all states (b†)n|Ωi, a spectrum whose dimensionality is that of a one rather than a two-dimensional harmonic oscillator, even while the complete Fock space has the dimensionality of the two-dimensional oscillator.” With a pure fourth-order equation of motion being of the form 2 2 2 (∂t −∇ ) φ(x)=0, (1) the solutions are of the form ¯ ¯ φ(x)= eik·x¯−iωt, φ(x)= t eik·x¯−iωt.
    [Show full text]
  • New Type of Black Hole Detected in Massive Collision That Sent Gravitational Waves with a 'Bang'
    New type of black hole detected in massive collision that sent gravitational waves with a 'bang' By Ashley Strickland, CNN Updated 1200 GMT (2000 HKT) September 2, 2020 <img alt="Galaxy NGC 4485 collided with its larger galactic neighbor NGC 4490 millions of years ago, leading to the creation of new stars seen in the right side of the image." class="media__image" src="//cdn.cnn.com/cnnnext/dam/assets/190516104725-ngc-4485-nasa-super-169.jpg"> Photos: Wonders of the universe Galaxy NGC 4485 collided with its larger galactic neighbor NGC 4490 millions of years ago, leading to the creation of new stars seen in the right side of the image. Hide Caption 98 of 195 <img alt="Astronomers developed a mosaic of the distant universe, called the Hubble Legacy Field, that documents 16 years of observations from the Hubble Space Telescope. The image contains 200,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the Big Bang. " class="media__image" src="//cdn.cnn.com/cnnnext/dam/assets/190502151952-0502-wonders-of-the-universe-super-169.jpg"> Photos: Wonders of the universe Astronomers developed a mosaic of the distant universe, called the Hubble Legacy Field, that documents 16 years of observations from the Hubble Space Telescope. The image contains 200,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the Big Bang. Hide Caption 99 of 195 <img alt="A ground-based telescope's view of the Large Magellanic Cloud, a neighboring galaxy of our Milky Way.
    [Show full text]
  • Giant Low Surface Brightness Galaxies: Evolution in Isolation
    J. Astrophys. Astr. (2013) 34, 19–31 c Indian Academy of Sciences Giant Low Surface Brightness Galaxies: Evolution in Isolation M. Das Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034, India. e-mail: [email protected] Received 4 April 2013; accepted 17 April 2013 Abstract. Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in surface brightness. They often have bright bulges that are similar to those found in early type galaxies. The bulges can host low luminosity Active Galactic Nuclei (AGN) that have relatively low mass black holes. GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies. In fact many GLSB galaxies are found under dense regions close to the edges of voids. These galaxies have very massive dark matter halos that also contribute to their stability and lack of evolution. In this paper we briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive dark matter halos have led to the low star formation rates and the slower rate of evolution in these galaxies. Key words. Galaxies: evolution—galaxies: nuclei—galaxies: active— galaxies: ISM—galaxies: spiral—cosmology: dark matter. 1. Introduction Giant Low Surface Brightness (GLSB) galaxies are some of the largest spiral galax- ies in our nearby universe.
    [Show full text]
  • COSMOS Astronomy & Astrophysics Cluster 2014 PROJECT
    COSMOS Astronomy & Astrophysics Cluster 2014 PROJECT DESCRIPTIONS You will work on your research projects during Project Labs on Tuesday and Thursday from 1:15-4:00 pm. The labs are headed by Professor Tammy Smecker-Hane ([email protected]) and your teaching assistants. Each project will be done by a group of 2 to 3 students. Students will be assigned to a project group based on their stated interests. In Projects 7 – 8, students are given data taken previously for research projects done with large telescopes. In Projects 1 – 6, students actually will use the telescopes at the UCI Observatory to obtain their own data, guided by a teaching assistant or professor. One or two groups will be scheduled to use the Observatory each night Monday – Thursday nights of Weeks 1–3. When you get to computer lab, please bookmark our cluster’s web page, http://wwww.physics.uci.edu/ ˜observat/cosmos/cosmos index.html. On the menu on the left-hand side of the page, you will see up-to-date information on the nightly observing schedule, project groups, etc. Please check the observing schedule daily as things may change, especially if we have cloudy weather, and it is YOUR responsiblity to know which nights you are scheduled to observe and when to meet the van that will take you to the observatory that night. The following pages show a short description of the projects, the assigned reading and ques- tions for each. The reading assignments reference chapters, figures, tables, etc. in your textbook, 21st Century Astronomy (3rd Edition), by J.
    [Show full text]
  • New Clues on Dark Matter from the Darkest Galaxies 18 December 2019
    New clues on dark matter from the darkest galaxies 18 December 2019 a very homogeneous behaviour. This result consolidates several clues on the presence and behaviour of dark matter, opening up new scenarios on its interactions with bright matter. Lights and shadows on matter It is there but you cannot see it. Dark matter appears to account for approximately 90% of the mass of the Universe; it has effects that can be detected on the other objects present in the cosmos, and yet it cannot be observed directly because it does not emit light (at least in the way in which it has been searched for to date). One of the methods for studying it is that of rotation curves of the galaxies, systems that describe the trend of the speed of stars based on their distance from the centre of the galaxy. The variations observed are NASA/ESA Hubble Space Telescope image capturing UGC 477, a low surface brightness galaxy located just connected to the gravitational interactions due to over 110 million light-years away in the constellation of the presence of stars and to the dark component of Pisces (The Fish). Credit: ESA/Hubble & matter. Consequently, the rotation curves are a NASAAcknowledgement: Judy Schmidt good way to have information on the dark matter based on its effects on what it is possible to observe. In particular, the analysis of the rotation curves can be conducted individually or on groups They are called low-surface-brightness galaxies of galaxies that share similar characteristics and it is thanks to them that important according to the universal rotation curve (URC) confirmations and new information have been method.
    [Show full text]
  • Arxiv:2005.03520V1 [Astro-Ph.GA] 7 May 2020
    universe Review Fundamental Properties of the Dark and the Luminous Matter from the Low Surface Brightness Discs Paolo Salucci *,†,‡ and Chiara di Paolo ‡ INFN Sezione di Trieste, Via A. Valerio 2, 34127 Trieste, Italy; [email protected] * Correspondence: [email protected] † Current address: SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy. ‡ These authors contributed equally to this work. Abstract: Dark matter (DM) is one of the biggest mystery in the Universe. In this review, we start reporting the evidences for this elusive component and discussing about the proposed particle candidates and scenarios for such phenomenon. Then, we focus on recent results obtained for rotating disc galaxies, in particular for low surface brightness (LSB) galaxies. The main observational properties related to the baryonic matter in LSBs, investigated over the last decades, are briefly recalled. Next, these galaxies are analyzed by means of the mass modelling of their rotation curves both individual and stacked. The latter analysis, via the universal rotation curve (URC) method, results really powerful in giving a global or universal description of the properties of these objects. We report the presence in LSBs of scaling relations among their structural properties that result comparable with those found in galaxies of different morphologies. All this confirms, in disc systems, the existence of a strong entanglement between the luminous matter (LM) and the dark matter (DM). Moreover, we report how in LSBs the Citation: Salucci, P.; di Paolo, C. tight relationship between their radial gravitational accelerations g and their baryonic components gb Fundamental Properties of the Dark results to depend also on the stellar disk length scale and the radius at which the two accelerations and the Luminous Matter from the have been measured.
    [Show full text]
  • New Evidence for Dark Matter
    New evidence for dark matter A. Boyarsky1,2, O. Ruchayskiy1, D. Iakubovskyi2, A.V. Macci`o3, D. Malyshev4 1Ecole Polytechnique F´ed´erale de Lausanne, FSB/ITP/LPPC, BSP CH-1015, Lausanne, Switzerland 2Bogolyubov Institute for Theoretical Physics, Metrologichna str., 14-b, Kiev 03680, Ukraine 3Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 4Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland Observations of star motion, emissions from hot ionized gas, gravitational lensing and other tracers demonstrate that the dynamics of galaxies and galaxy clusters cannot be explained by the Newtonian potential produced by visible matter only [1–4]. The simplest resolution assumes that a significant fraction of matter in the Universe, dominating the dynamics of objects from dwarf galaxies to galaxy clusters, does not interact with electromagnetic radiation (hence the name dark matter). This elegant hypothesis poses, however, a major challenge to the highly successful Standard Model of particle physics, as it was realized that dark matter cannot be made of known elementary particles [4]. The quest for direct evidence of the presence of dark matter and for its properties thus becomes of crucial importance for building a fundamental theory of nature. Here we present a new universal relation, satisfied by matter distributions at all observed scales, and show its amaz- ingly good and detailed agreement with the predictions of the most up-to-date pure dark matter simulations of structure formation in the Universe [5–7]. This behaviour seems to be insensitive to the complicated feedback of ordinary matter on dark matter.
    [Show full text]
  • An Explanation for the Unexpected Diversity of Dwarf Galaxy Rotation Curves
    AN EXPLANATION FOR THE UNEXPECTED DIVERSITY OF DWARF GALAXY ROTATION CURVES by Kyle Oman B.Sc., University of Waterloo, 2011 M.Sc., University of Waterloo, 2013 A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in the Department of Physics and Astronomy c Kyle Oman, 2017 University of Victoria All rights reserved. This dissertation may not be reproduced in whole or in part, by photocopying or other means, without the permission of the author. ii AN EXPLANATION FOR THE UNEXPECTED DIVERSITY OF DWARF GALAXY ROTATION CURVES by Kyle Oman B.Sc., University of Waterloo, 2011 M.Sc., University of Waterloo, 2013 Supervisory Committee Dr. J. F. Navarro, Supervisor (Department of Physics and Astronomy) Dr. F. Herwig, Departmental Member (Department of Physics and Astronomy) Dr. F. Diacu, Outside Member (Department of Mathematics and Statistics) iii ABSTRACT The cosmological constant + cold dark matter (ΛCDM) theory is the `standard model' of cosmology. Encoded in it are extremely accurate descriptions of the large scale structure of the Universe, despite a very limited number of degrees of freedom. The model struggles, however, to explain some measurements on galactic and smaller scales. The shape of the dark matter distribution toward the centres of galaxies is predicted to be steeply increasing in density (`cuspy') by the theory, yet observations of the rotation curves of some galaxies suggest that it instead reaches a central density plateau (a `core'). This discrepancy is termed the `cusp-core problem'. I propose a new way of quantifying this problem as a diversity in the central mass content of galaxies.
    [Show full text]
  • Hubble Sees Galaxy Hiding in the Night Sky 2 May 2016
    Hubble sees galaxy hiding in the night sky 2 May 2016 LSB galaxies such as UGC 477 instead appear to be dominated by dark matter, making them excellent objects to study to further our understanding of this elusive substance. However, due to an underrepresentation in galactic surveys—caused by their characteristic low brightness—their importance has only been realized relatively recently. Provided by NASA Credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt This striking NASA/ESA Hubble Space Telescope image captures the galaxy UGC 477, located just over 110 million light-years away in the constellation of Pisces (The Fish). UGC 477 is a low surface brightness (LSB) galaxy. First proposed in 1976 by Mike Disney, the existence of LSB galaxies was confirmed only in 1986 with the discovery of Malin 1. LSB galaxies like UGC 477 are more diffusely distributed than galaxies such as Andromeda and the Milky Way. With surface brightnesses up to 250 times fainter than the night sky, these galaxies can be incredibly difficult to detect. Most of the matter present in LSB galaxies is in the form of hydrogen gas, rather than stars. Unlike the bulges of normal spiral galaxies, the centers of LSB galaxies do not contain large numbers of stars. Astronomers suspect that this is because LSB galaxies are mainly found in regions devoid of other galaxies, and have therefore experienced fewer galactic interactions and mergers capable of triggering high rates of star formation. 1 / 2 APA citation: Hubble sees galaxy hiding in the night sky (2016, May 2) retrieved 29 September 2021 from https://phys.org/news/2016-05-hubble-galaxy-night-sky.html This document is subject to copyright.
    [Show full text]
  • Kinematics of Radion Field
    Eur. Phys. J. C (2016) 76:648 DOI 10.1140/epjc/s10052-016-4512-z Regular Article - Theoretical Physics Kinematics of radion field: a possible source of dark matter Sumanta Chakraborty 1,a, Soumitra SenGupta2,b 1 IUCAA, Post Bag 4, Ganeshkhind, Pune University Campus, Pune 411 007, India 2 Department of Theoretical Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India Received: 11 July 2016 / Accepted: 11 November 2016 / Published online: 25 November 2016 © The Author(s) 2016. This article is published with open access at Springerlink.com Abstract The discrepancy between observed virial and itational force. For cloud velocity v(r), the centrifugal force baryonic mass in galaxy clusters have lead to the missing is given by v2/r and the gravitational force by GM(r)/r 2, mass problem. To resolve this, a new, non-baryonic mat- where M(r) stands for total gravitational mass within radius ter field, known as dark matter, has been invoked. However, r. Equating these two will lead to the mass profile of the till date no possible constituents of the dark matter compo- galaxy: M(r) = rv2/G. This immediately posed serious nents are known. This has led to various models, by modi- problem, for at large distances from the center of the galaxy, fying gravity at large distances to explain the missing mass the velocity remains nearly constant v ∼ 200 km/s, which problem. The modification to gravity appears very naturally suggests that mass inside radius r should increase monotoni- when effective field theory on a lower-dimensional mani- cally with r, even though at large distance very little luminous fold, embedded in a higher-dimensional spacetime is con- matter can be detected [2–4].
    [Show full text]