Numerical Hydrodynamics in General Relativity
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Supernovae Sparked by Dark Matter in White Dwarfs
Supernovae Sparked By Dark Matter in White Dwarfs Javier F. Acevedog and Joseph Bramanteg;y gThe Arthur B. McDonald Canadian Astroparticle Physics Research Institute, Department of Physics, Engineering Physics, and Astronomy, Queen's University, Kingston, Ontario, K7L 2S8, Canada yPerimeter Institute for Theoretical Physics, Waterloo, Ontario, N2L 2Y5, Canada November 27, 2019 Abstract It was recently demonstrated that asymmetric dark matter can ignite supernovae by collecting and collapsing inside lone sub-Chandrasekhar mass white dwarfs, and that this may be the cause of Type Ia supernovae. A ball of asymmetric dark matter accumulated inside a white dwarf and collapsing under its own weight, sheds enough gravitational potential energy through scattering with nuclei, to spark the fusion reactions that precede a Type Ia supernova explosion. In this article we elaborate on this mechanism and use it to place new bounds on interactions between nucleons 6 16 and asymmetric dark matter for masses mX = 10 − 10 GeV. Interestingly, we find that for dark matter more massive than 1011 GeV, Type Ia supernova ignition can proceed through the Hawking evaporation of a small black hole formed by the collapsed dark matter. We also identify how a cold white dwarf's Coulomb crystal structure substantially suppresses dark matter-nuclear scattering at low momentum transfers, which is crucial for calculating the time it takes dark matter to form a black hole. Higgs and vector portal dark matter models that ignite Type Ia supernovae are explored. arXiv:1904.11993v3 [hep-ph] 26 Nov 2019 Contents 1 Introduction 2 2 Dark matter capture, thermalization and collapse in white dwarfs 4 2.1 Dark matter capture . -
Arxiv:2101.12220V2 [Astro-Ph.HE]
Neutron Stars Harboring a Primordial Black Hole: Maximum Survival Time Thomas W. Baumgarte1 and Stuart L. Shapiro2, 3 1Department of Physics and Astronomy, Bowdoin College, Brunswick, Maine 04011 2Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 3Department of Astronomy and NCSA, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 We explore in general relativity the survival time of neutron stars that host an endoparasitic, possibly primordial, black hole at their center. Corresponding to the minimum steady-state Bondi accretion rate for adiabatic flow that we found earlier for stiff nuclear equations of state (EOSs), we derive analytically the maximum survival time after which the entire star will be consumed by the black hole. We also show that this maximum survival time depends only weakly on the stiffness for polytropic EOSs with Γ ≥ 5/3, so that this survival time assumes a nearly universal value that depends on the initial black hole mass alone. Establishing such a value is important for constraining −16 −10 the contribution of primordial black holes in the mass range 10 M⊙ . M . 10 M⊙ to the dark-matter content of the Universe. Primordial black holes (PBHs) that may have formed the spherical, steady-state, Bondi accretion formula, in the early Universe (see, e.g., [1, 2]) have long been con- M 2ρ sidered candidates for contributing to, if not accounting M˙ =4πλ 0 (1) for, the mysterious and elusive dark matter (see, e.g., [3], a3 as well as [4] for a recent review). Constraints on the PBH contribution to the dark matter have been estab- for adiabatic flow ([18]; see also [19] for a textbook treat- lished by a number of different observations. -
Lecture Notes in Astrophysical Fluid Dynamics
Lecture Notes in Astrophysical Fluid Dynamics Mattia Sormani November 19, 2017 1 Contents 1 Hydrodynamics6 1.1 Introductory remarks..........................6 1.2 The state of a fluid...........................6 1.3 The continuity equation........................7 1.4 The Euler equation, or F = ma ....................8 1.5 The choice of the equation of state.................. 10 1.6 Manipulating the fluid equations................... 14 1.6.1 Writing the equations in different coordinate systems.... 14 1.6.2 Indecent indices......................... 16 1.6.3 Tables of unit vectors and their derivatives.......... 17 1.7 Conservation of energy......................... 18 1.8 Conservation of momentum...................... 21 1.9 Lagrangian vs Eulerian view...................... 21 1.10 Vorticity................................. 22 1.10.1 The vorticity equation..................... 23 1.10.2 Kelvin circulation theorem................... 24 1.11 Steady flow: the Bernoulli's equation................. 26 1.12 Rotating frames............................. 27 1.13 Viscosity and thermal conduction................... 28 1.14 The Reynolds number......................... 33 1.15 Adding radiative heating and cooling................. 35 1.16 Summary................................ 36 1.17 Problems................................. 37 2 Magnetohydrodynamics 38 2.1 Basic equations............................. 38 2.2 Magnetic tension............................ 44 2.3 Magnetic flux freezing......................... 45 2.4 Magnetic field amplification..................... -
Bondi-Hoyle Accretion
A Review of Bondi–Hoyle–Lyttleton Accretion Richard Edgar a aStockholms observatorium, AlbaNova universitetscentrum, SE-106 91, Stockholm, Sweden Abstract If a point mass moves through a uniform gas cloud, at what rate does it accrete ma- terial? This is the question studied by Bondi, Hoyle and Lyttleton. This paper draws together the work performed in this area since the problem was first studied. Time has shown that, despite the simplifications made, Bondi, Hoyle and Lyttleton made quite accurate predictions for the accretion rate. Bondi–Hoyle–Lyttleton accretion has found application in many fields of astronomy, and these are also discussed. Key words: accretion PACS: 95.30.Lz, 97.10.Gz, 98.35.Mp, 98.62.Mw 1 Introduction arXiv:astro-ph/0406166v2 21 Jun 2004 In its purest form, Bondi–Hoyle–Lyttleton accretion concerns the supersonic motion of a point mass through a gas cloud. The cloud is assumed to be free of self-gravity, and to be uniform at infinity. Gravity focuses material behind the point mass, which can then accrete some of the gas. This problem has found applications in many areas of astronomy, and this paper is an attempt to address the lack of a general review of the subject. I start with a short summary of the original work of Bondi, Hoyle and Lyt- tleton, followed by a discussion of the numerical simulations performed. Some issues in Bondi–Hoyle–Lyttleton accretion are discussed, before a brief sum- mary of the fields in which the geometry has proved useful. Email address: [email protected] (Richard Edgar). -
Accretion Processes on a Black Hole Sandip K
Contents Abstract ........................................... ............. 4 1: Introduction ..................................... .............. 5 1.1 Some General Issues Related to Black Hole Astrophysics . .................. 7 1.1.1 Formation of Black Holes ......................... ....................... 7 1.1.2 Fueling Active Galactic Nuclei . ........................ 9 1.1.3 Evolution of Galactic Centers .................... ....................... 12 1.1.4 Black Holes in Galactic Halos? .................... ..................... 13 1.1.5 Some Signatures of Black Holes .................... ..................... 14 1.2 Difference between Motions around a Newtonian Star and a BlackHole ... 16 1.3 Basics of Pseudo-Newtonian Geometries . .................... 21 1.4 Remarks About Units and Dimensions . .................. 23 2: Spherical Accretion ............................... ............ 24 2.1 Bondi Accretion on a Newtonian Star .................. ................... 25 2.1.1 Basic Equations ................................ ........................ 25 2.1.2 Phase Space Behaviour of the Bondi Flow . ................. 28 2.2 Bondi Flow on a Black Hole ........................... ................... 30 2.2.1 In Schwarzschild Geometry ....................... ....................... 30 2.2.2 In pseudo-Newtonian Geometry .................... ..................... 31 2.3 Bondi Flow with Simple Radiative Transfer . ................... 32 2.4 Bondi Flow with General Radiative Transfer . ................... 32 2.4.1 Single Temperature Solutions -
Brian David Metzger
Curriculum Vitae, Updated 10/20 Brian David Metzger Columbia University Email: [email protected] Department of Physics Web: http://www.columbia.edu/∼bdm2129 909 Pupin Hall, MC 5217 Phone: (212) 854-9702 New York, NY 10027 Fax: (212) 854-3379 ACADEMIC POSITIONS 07/20− Full Professor of Physics, Columbia University 07/19−07/20 Visiting Scholar, Simons Flatiron Institute 01/17−07/20 Associate Professor of Physics, Columbia University 01/13−01/17 Assistant Professor of Physics, Columbia University 09/12−12/12 Lyman Spitzer Jr. Fellow, Princeton University 09/09−12/12 NASA Einstein Fellow, Princeton University EDUCATION 08/03−05/09 University of California at Berkeley M.A. & Ph.D. in Physics (Thesis Adviser: Prof. Eliot Quataert) Dissertation: \Theoretical Models of Gamma-Ray Burst Central Engines" 08/99−05/03 The University of Iowa B.S. in Physics, Astronomy, & Mathematics (Highest Distinction) SELECT HONORS, FELLOWSHIPS and AWARDS 2020 Blavatnik National Laureate in Natural Sciences & Engineering 2020 Simons Investigator in Mathematics and Theoretical Physics 2019 Simons Fellow in Mathematics and Theoretical Physics 2019 2020 Decadal Survey in Astronomy & Astrophysics, Program Panelist 2019 Salpeter Honorary Lecturer, Cornell 2019 Bruno Rossi Prize, American Astronomical Society 2018,19,20 Blavatnik National Awards for Young Scientists, Finalist 2019 New Horizons Breakthrough Prize in Physics 2018 Charles and Thomas Lauritsen Honorary Lecture, Caltech 2016 Scialog Fellow, Research Science Corporation 2014 Alfred P. Sloan Research Fellowship 2009−12 NASA Einstein Fellowship, Princeton 2009 Dissertation Prize, AAS High Energy Astrophysics Division 2009 NASA Hubble Fellowship 2009 Lyman Spitzer Jr. Fellowship, Princeton 2009 Mary Elizabeth Uhl Prize, UC Berkeley Astronomy 2005−08 NASA Graduate Student Research Fellowship 2003 James A. -
Arxiv:2002.12778V2 [Astro-Ph.CO] 9 May 2021 8
CONSTRAINTS ON PRIMORDIAL BLACK HOLES Bernard Carr,1, 2, ∗ Kazunori Kohri,3, 4, 5, y Yuuiti Sendouda,6, z and Jun'ichi Yokoyama2, 5, 7, 8, x 1School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK 2Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 3KEK Theory Center, IPNS, KEK, Tsukuba, Ibaraki 305-0801, Japan 4The Graduate University for Advanced Studies (SOKENDAI), Tsukuba, Ibaraki 305-0801, Japan 5Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Kashiwa, Chiba 277-8568, Japan 6Graduate School of Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561, Japan 7Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 8Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo 113-0033, Japan (Dated: Tuesday 11th May, 2021, 00:43) We update the constraints on the fraction of the Universe that may have gone into primordial black holes (PBHs) over the mass range 10−5{1050 g. Those smaller than ∼ 1015 g would have evaporated by now due to Hawking radiation, so their abundance at formation is constrained by the effects of evaporated particles on big bang nucleosynthesis, the cosmic microwave background (CMB), the Galactic and extragalactic γ-ray and cosmic ray backgrounds and the possible generation of stable Planck mass relics. PBHs larger than ∼ 1015 g are subject to a variety of constraints associated with gravitational lensing, dynamical effects, influence on large-scale structure, accretion and gravitational waves. -
Accretion Onto Black Holes from Large Scales Regulated by Radiative Feedback
Abstract Title of Dissertation: Accretion onto Black Holes from Large Scales Regulated by Radiative Feedback KwangHo Park, Doctor of Philosophy, 2012 Dissertation directed by: Professor Massimo Ricotti Department of Astronomy This thesis focuses on radiation-regulated gas accretion onto black holes (BHs) from galactic scales emphasizing the role of thermal and radiation pressure in lim- iting gas supply to the BH. Assuming quasi-spherical symmetry, we explore how the gas accretion depends on free parameters such as radiative efficiency, BH mass, ambient gas density/temperature, and the spectral index of the radiation. Our nu- merical simulations show an oscillatory behavior of the accretion rate, and thus the luminosity from the BH. We present a model for the feedback loop and provide analytical relationships for the average/maximum accretion rate and the period of the accretion bursts. The thermal structure inside the Str¨omgrensphere is a key factor for the regulation process, while with increasing ambient gas density and mass of BHs, eventually the accretion rate becomes limited by radiation pressure. The period of the luminosity bursts is proportional to the average size of the ionized hot bubble, but we discover that there are two distinct modes of oscillations with very different duty cycles, and that are governed by different depletion processes of the gas inside the ionized bubble. We also study how angular momentum of the gas affects the accretion process. In the second part of the thesis, we study the growth rate and luminosity of BHs in motion with respect to their surrounding medium. We run a large set of two-dimensional axis-symmetric simulations to explore a large parameter space of initial conditions and formulate an analytical model for the accretion. -
Turning Points in the Evolution of Isolated Neutron Stars' Magnetic
Turning Points in the Evolution of Isolated Neutron Stars’ Magnetic Fields U. Geppert Departament de F´ısica Aplicada, Univeritat d’ Alacant, ap. Correus 99, 03080 Alacant, Spain, [email protected] Summary. During the life of isolated neutron stars (NSs) their magnetic field passes through a variety of evolutionary phases. Depending on its strength and structure and on the physical state of the NS (e.g. cooling, rotation), the field looks qualitatively and quantitatively different after each of these phases. Three of them, the phase of MHD instabilities immediately after NS’s birth, the phase of fallback which may take place hours to months after NS’s birth, and the phase when strong temperature gradients may drive thermoelectric instabilities, are concentrated in a period lasting from the end of the proto–NS phase until 100, perhaps 1000 years, when the NS has become almost isothermal. The further evolution of the magnetic field proceeds in general inconspicuous since the star is in isolation. However, as soon as the product of Larmor frequency and electron relaxation time, the so–called mag- netization parameter (ωB τ), locally and/or temporally considerably exceeds unity, phases, also unstable ones, of dramatic changes of the field structure and magnitude can appear. An overview is given about that field evolution phases, the outcome of which makes a qualitative decision regarding the further evolution of the magnetic field and its host NS. 1 Introduction The energy of the magnetic fields of neutron stars (NSs) is even for magne- tar field strengths (∼ 1015 G) negligible in comparison with the gravitational energy of even the least massive NSs. -
A Review of Bondi–Hoyle–Lyttleton Accretion
New Astronomy Reviews 48 (2004) 843–859 www.elsevier.com/locate/newastrev A review of Bondi–Hoyle–Lyttleton accretion Richard Edgar * Stockholms Observatorium, AlbaNova Universitetscentrum, SE-106 91 Stockholm, Sweden Accepted 1 June 2004 Available online 2 July 2004 Abstract If a point mass moves through a uniform gas cloud, at what rate does it accrete material? This is the question studied by Bondi, Hoyle and Lyttleton. This paper draws together the work performed in this area since the problem was first studied. Time has shown that, despite the simplifications made, Bondi, Hoyle and Lyttleton made quite accurate predictions for the accretion rate. Bondi–Hoyle–Lyttleton accretion has found application in many fields of astronomy, and these are also discussed. Ó 2004 Elsevier B.V. All rights reserved. PACS: 95.30.Lz; 97.10.Gz; 98.35.Mp; 98.62.Mw Keyword: Accretion Contents 1. Introduction..................................................... 844 2. Basics.......................................................... 844 2.1. The analysis of Hoyle and Lyttleton . 844 2.2. Analytic solution. 845 2.3. The analysis of Bondi and Hoyle . 846 2.4. Connection to Bondi accretion . 849 3. Numericalsimulations.............................................. 849 3.1. Summary . 849 3.2. Examples in the literature . 850 4. Issues in Bondi–Hoyle–Lyttleton flow . 852 * Tel.: +46-8-5537-8552; fax: +46-8-5537-8510. E-mail address: [email protected] (R. Edgar). 1387-6473/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.newar.2004.06.001 844 R. Edgar / New Astronomy Reviews 48 (2004) 843–859 4.1. The drag force . 852 4.2. -
Arxiv:2108.08982V1 [Astro-Ph.HE] 20 Aug 2021 Luminosities Than the Non-Repeating Ones
Draft version August 23, 2021 Typeset using LATEX default style in AASTeX63 Reconciling the 16.35-day period of FRB 20180916B with jet precession Hao-Yan Chen,1 Wei-Min Gu,1 Mouyuan Sun,1 Tong Liu,1 and Tuan Yi1 1Department of Astronomy, Xiamen University, Xiamen, Fujian 361005, P. R. China (Received XXX; Revised YYY; Accepted ZZZ) Submitted to ApJ ABSTRACT A repeating fast radio burst (FRB), FRB 20180916B (hereafter FRB 180916), was reported to have a 16.35-day period. This period might be related to a precession period. In this paper, we investigate two precession models to explain the periodic activity of FRB 180916. In both models, the radio emission of FRB 180916 is produced by a precessing jet. For the first disk-driven jet precession model, −8 an extremely low viscous parameter (i.e., the dimensionless viscosity parameter α . 10 ) is required to explain the precession of FRB 180916, which implies its implausibility. For the second tidal force- driven jet precession model, we consider a compact binary consists of a neutron star/black hole and a white dwarf; the white dwarf fills its Roche lobe and mass transfer occurs. Due to the misalignment between the disk and orbital plane, the tidal force of the white dwarf can drive jet precession. We show that the relevant precession periods are several days to hundreds of days, depending on the specific accretion rates and component masses. The duration of FRB 180916 generation in the binary with extremely high accretion rate will be several thousand years. Keywords: Compact binary stars (283)|Jets (870)|Stellar accretion disks (1579)|White dwarf stars (1799)|Radio transient sources (2008) 1. -
High Energy Signatures of Quasi-Spherical Accretion Onto
High energy signatures of quasi-spherical accretion onto rotating, magnetized neutron star in the ejector-accretor intermediate state W. Bednarek and P. Banasi´nski Department of Astrophysics, University of Ł´od´z, ul. Pomorska 149/153, 90-236 Ł´od´z, Poland Abstract We consider a simple scenario for the accretion of matter onto a neutron star in order to under- stand processes in the inner pulsar magnetosphere during the transition stage between different accretion modes. A simple quasi-spherical accretion process onto rotating, magnetized com- pact object is analysed in order to search for the radiative signatures which could appear during transition between ejecting and accreting modes. It is argued that different accretion modes can be present in a single neutron star along different magnetic field lines for specific range of pa- rameters characterising the pulsar (rotational period, surface magnetic field strength) and the density of surrounding medium. The radiation processes characteristic for the ejecting pulsar, i.e. curvature and synchrotron radiation produced by primary electrons in the pulsar outer gap, are expected to be modified by the presence of additional thermal radiation from the neutron star surface. We predict that during the transition from the pure ejector to the pure accretor mode (or vice versa) an intermediate accretion state can be distinguished which is characterised by the γ-ray spectra of pulsars truncated below 1 GeV due to the absorption of synchro/curvature spectrum produced in the pulsar gaps. ∼ Keywords: binaries: general — pulsars: general — accretion — radiation mechanisms: non-thermal — gamma-rays: stars 1. 2. Introduction The importance of the accretion of matter onto compact objects as a key process for generation of energy around compact objects has been recognized since early 70-ties.