DOCSLIB.ORG

Magnetodynamics Inside and Outside Magnetars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnetodynamics Inside and Outside Magnetars Magnetodynamics Inside and Outside Magnetars Xinyu Li Submitted in partial fulfillment ofthe requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2019 ©2019 Xinyu Li All Rights Reserved Abstract Magnetodynamics Inside and Outside Magnetars Xinyu Li The ultra-strong magnetic fields of magnetars have profound implications for their radiative phenomena. We study the dynamics of strong magnetic fields inside and outside magnetars. Inside the magnetar, the strong magnetic stress can break the crust and trigger plastic failures. The interaction between magnetic fields and plastic failures is studied in two scenarios: 1. Internal Hall waves launched from the core-crust interface can initiate plastic failures and lead to X-ray outbursts. 2. External Alfven waves produced by giant flares can also initiate crustal plastic failures which dissipate the waves and give rise to delayed thermal afterglow. The crustal dissipation of Alfven waves competes with the magnetospheric dissipation outside the magnetar. Using a high order simulation of Force-Free Electrodynamics (FFE), we found that the magnetospheric dissipation of Alfven waves is generally slow and most wave energy will dissipate inside the magnetar. Contents List of Figures v Chapter 1 Introduction 1 1.1 Neutrons Stars . 2 1.1.1 Theoretical and observational discovery . .2 1.1.2 Structure of neutron stars . 5 1.2 Magnetars . 10 1.2.1 Discovery . 10 1.2.2 Magnetar Activities . 12 1.2.3 Theoretical Models . 16 1.3 This Dissertation . 24 Chapter 2 Magnetohydrodynamics (MHD) 26 2.1 Ideal MHD . 26 2.1.1 Nonrelativistic ideal MHD . 26 2.1.2 Waves in nonrelativistic ideal MHD . 28 2.1.3 Relativistic MHD (RMHD) . 29 2.2 Force-Free Electrodynamics (FFE) . 29 2.2.1 Wave solutions . 30 2.2.2 Wave-wave interactions . 33 i 2.3 Non-ideal corrections . 35 Chapter 3 Magnetar Outbursts from Avalanche of Hall Waves 38 3.1 Hall waves . 39 3.1.1 Generation of Hall waves . 41 3.2 Plastic failures . 44 3.2.1 Stress balance . 44 3.2.2 Mechanical failure . 45 3.2.3 Heat transfer and thermoplastic waves . 46 3.3 Hall-mediated avalanche . 48 3.4 Twisted external field . 52 3.5 Global Simulation . 54 3.5.1 Setup . 54 3.5.2 Results . 58 3.6 Discussion . 65 Chapter 4 Plastic Damping of Alfvén Waves in Magnetar Crusts 69 4.1 Wave transmission into the crust . 70 4.1.1 Transmission coefficient . 70 4.1.2 Numerical model . 74 4.2 Plastic Heating . 77 4.2.1 Pre-flare temperature profile . 77 4.2.2 Plastic flow . 79 4.2.3 Wave damping and post-flare crustal temperature . 81 4.3 Cooling . 84 4.4 Discussion . 88 4.4.1 Plastic damping and cooling . 88 ii 4.4.2 Other mechanisms of Alfvén wave damping . 91 4.4.3 Observed afterglow . 92 Chapter 5 Dissipation of Alfvén Waves in Magnetar Magnetospheres 95 5.1 Numerical setup . 98 5.1.1 Computational setting . 98 5.1.2 Solution scheme . 98 5.1.3 Constraint preservation . 100 5.1.4 Maintaining magnetic dominance . 101 5.1.5 Dissipation channels in FFE simulations . 101 5.1.6 Numerical diagnostics . 103 5.2 Spectral evolution of wave turbulence . 104 5.2.1 3D simulations . 104 5.2.2 2D simulations . 109 5.3 Local dissipation and escape of waves . 112 5.3.1 Turbulent dissipation rate without wave escape . 113 5.3.2 Turbulent cascade with escaping fast modes . 114 5.4 Enhanced immediate dissipation and FFE failure . 116 5.4.1 Immediate dissipation observed in FFE simulations . 116 5.4.2 MHD simulations and the spurious character of immediate dissipation in FFE . 120 5.5 Discussion . 124 5.5.1 Summary of results . 124 5.5.2 Fate of wave energy in magnetar flares . 127 Chapter 6 Conclusions 129 Bibliography 132 iii Appendix A Wave Turbulence 143 A.1 Weak nonlinearity expansion . 145 A.2 Generating function . 147 A.3 Kinetic equation . 151 Appendix B Resonant Three Wave Interactions in FFE 153 iv List of Figures Figure 1.1 A record of pulsating radio source . 4 Figure 1.2 A cartoon illustrates the structure of a neutron star . 6 Figure 1.3 Equation of state and mass-radius relation for neutron stars . 7 Figure 1.4 Neutrino cooling rate in the core of neutron stars . 8 Figure 1.5 P − PÛ diagram for pulsars and magnetars . 12 Figure 1.6 Light curve for the 2004 giant flare SGR 1806-20 . 14 Figure 1.7 Light curves of eight magnetar outbursts . 15 Figure 1.8 Relation between shear stress and strain of materials in the neutron star crust 17 Figure 1.9 Structure of the thermoplastic wave front . 18 Figure 1.10 Formation of the equatorial current sheet in an over-twisted magnetar magnetosphere. 20 Figure 1.11 The evolution of hotspots observed on transient magnetars following their outbursts . 22 Figure 1.12 Sketch of a twist magnetic loop. 23 Figure 3.1 Components of magnetic field in the self-similar solution of Hall waves .42 Figure 3.2 Generation of Hall waves in the magnetar crust . 43 Figure 3.3 Profile of the horizontal magnetic field . 49 Figure 3.4 Numerical simulation demonstrating the Hall-mediated failure of the crust 50 Figure 3.5 Illustration for the magnetic field lines in the crust and in the magnetosphere 54 v Figure 3.6 Snapshots of the magnetic field evolution . 58 Figure 3.7 Spacetime diagram for failure generation and propagation in the crust . 59 Figure 3.8 Radiation flux from the outburst simulation . 60 Figure 3.9 Spacetime diagram for a giant thermoplastic wave . 61 Figure 3.10 Radiation flux from the outburst simulation for a giant thermoplastic wave62 Figure 3.11 Evolution of surface displacement . 63 Figure 3.12 Evolution of the radiation flux . 64 Figure 3.13 Evolution of the free energy . 64 Figure 4.1 Density ρ¹zº and shear modulus µ¹zº of the neutron star crust . 71 Figure 4.2 Comparison between wavelength and characteristic scale in the crust . 73 Figure 4.3 Transmission coefficient T as a function of vertical magnetic field Bz . 74 Figure 4.4 A snapshot of the wave after four reflection/transmission events . 76 Figure 4.5 Shear wave propagation in the magnetar crust viewed on the spacetime diagram . 82 Figure 4.6 Energy evolution during the reflection of Alfvén waves off the crust .83 Figure 4.7 Temperature profile after the magnetospheric Alfvén waves have been absorbed by the crust . 84 Figure 4.8 Evolution of the crustal temperature profiles . 86 Figure 4.9 Fraction of the post-flare crustal heat lost through surface emission and various channels of neutrino emission . 87 Figure 4.10 Surface thermal flux caused by the plastic heating in the giant flare .87 Figure 5.1 Magnetic field lines passing through one of the Alfvén wave packets .105 Figure 5.2 Free energy evolution for different resolutions in 3D simulations . .106 Figure 5.3 Development of turbulent spectrum in 3D simulations . 107 Figure 5.4 Turbulence spectrum in k? in four 3D simulations . 108 Figure 5.5 Free energy evolution for different resolutions in the 2D model . .109 vi Figure 5.6 Spectrum evolution for the 2D simulation . 110 Figure 5.7 The evolution of U0/U ¹tº in 2D simulations . 112 Figure 5.8 Dissipation of Alfvén wave packet energy U0 in 3D simulations . 113 Figure 5.9 Comparison between free energy evolution U ¹tº in the simulations with and without damping of fast modes . 116 Figure 5.10 Dissipated energy fraction.
Load more

Recommended publications
  • Pdf/44/4/905/5386708/44-4-905.Pdf
    MI-TH-214 INT-PUB-21-004 Axions: From Magnetars and Neutron Star Mergers to Beam Dumps and BECs Jean-François Fortin∗ Département de Physique, de Génie Physique et d’Optique, Université Laval, Québec, QC G1V 0A6, Canada Huai-Ke Guoy and Kuver Sinhaz Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA Steven P. Harrisx Institute for Nuclear Theory, University of Washington, Seattle, WA 98195, USA Doojin Kim{ Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA Chen Sun∗∗ School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel (Dated: February 26, 2021) We review topics in searches for axion-like-particles (ALPs), covering material that is complemen- tary to other recent reviews. The first half of our review covers ALPs in the extreme environments of neutron star cores, the magnetospheres of highly magnetized neutron stars (magnetars), and in neu- tron star mergers. The focus is on possible signals of ALPs in the photon spectrum of neutron stars and gravitational wave/electromagnetic signals from neutron star mergers. We then review recent developments in laboratory-produced ALP searches, focusing mainly on accelerator-based facilities including beam-dump type experiments and collider experiments. We provide a general-purpose discussion of the ALP search pipeline from production to detection, in steps, and our discussion is straightforwardly applicable to most beam-dump type and reactor experiments. We end with a selective look at the rapidly developing field of ultralight dark matter, specifically the formation of Bose-Einstein Condensates (BECs).
    [Show full text]
  • Magnetars: Explosive Neutron Stars with Extreme Magnetic Fields
    Magnetars: explosive neutron stars with extreme magnetic fields Nanda Rea Institute of Space Sciences, CSIC-IEEC, Barcelona 1 How magnetars are discovered? Soft Gamma Repeaters Bright X-ray pulsars with 0.5-10keV spectra modelled by a thermal plus a non-thermal component Anomalous X-ray Pulsars Bright X-ray transients! Transients No more distinction between Anomalous X-ray Pulsars, Soft Gamma Repeaters, and transient magnetars: all showing all kind of magnetars-like activity. Nanda Rea CSIC-IEEC Magnetars general properties 33 36 Swift-XRT COMPTEL • X-ray pulsars Lx ~ 10 -10 erg/s INTEGRAL • strong soft and hard X-ray emission Fermi-LAT • short X/gamma-ray flares and long outbursts (Kuiper et al. 2004; Abdo et al. 2010) • pulsed fractions ranging from ~2-80 % • rotating with periods of ~0.3-12s • period derivatives of ~10-14-10-11 s/s • magnetic fields of ~1013-1015 Gauss (Israel et al. 2010) • glitches and timing noise (Camilo et al. 2006) • faint infrared/optical emission (K~20; sometimes pulsed and transient) • transient radio pulsed emission (see Woods & Thompson 2006, Mereghetti 2008, Rea & Esposito 2011 for a review) Nanda Rea CSIC-IEEC How magnetar persistent emission is believed to work? • Magnetars have magnetic fields twisted up, inside and outside the star. • The surface of a young magnetar is so hot that it glows brightly in X-rays. • Magnetar magnetospheres are filled by charged particles trapped in the twisted field lines, interacting with the surface thermal emission through resonant cyclotron scattering. (Thompson, Lyutikov & Kulkarni 2002; Fernandez & Thompson 2008; Nobili, Turolla & Zane 2008a,b; Rea et al.
    [Show full text]
  • Pos(INTEGRAL 2010)091
    A candidate former companion star to the Magnetar CXOU J164710.2-455216 in the massive Galactic cluster Westerlund 1 PoS(INTEGRAL 2010)091 P.J. Kavanagh 1 School of Physical Sciences and NCPST, Dublin City University Glasnevin, Dublin 9, Ireland E-mail: [email protected] E.J.A. Meurs School of Cosmic Physics, DIAS, and School of Physical Sciences, DCU Glasnevin, Dublin 9, Ireland E-mail: [email protected] L. Norci School of Physical Sciences and NCPST, Dublin City University Glasnevin, Dublin 9, Ireland E-mail: [email protected] Besides carrying the distinction of being the most massive young star cluster in our Galaxy, Westerlund 1 contains the notable Magnetar CXOU J164710.2-455216. While this is the only collapsed stellar remnant known for this cluster, a further ~10² Supernovae may have occurred on the basis of the cluster Initial Mass Function, possibly all leaving Black Holes. We identify a candidate former companion to the Magnetar in view of its high proper motion directed away from the Magnetar region, viz. the Luminous Blue Variable W243. We discuss the properties of W243 and how they pertain to the former Magnetar companion hypothesis. Binary evolution arguments are employed to derive a progenitor mass for the Magnetar of 24-25 M Sun , just within the progenitor mass range for Neutron Star birth. We also draw attention to another candidate to be member of a former massive binary. 8th INTEGRAL Workshop “The Restless Gamma-ray Universe” Dublin, Ireland September 27-30, 2010 1 Speaker Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
    [Show full text]
  • Radio Observations of the Supermassive Black Hole at the Galactic Center and Its Orbiting Magnetar
    Radio Observations of the Supermassive Black Hole at the Galactic Center and its Orbiting Magnetar Rebecca Rimai Diesing Honors Thesis Department of Physics and Astronomy Northwestern University Spring 2017 Honors Thesis Advisor: Farhad Zadeh ! Radio Observations of the Supermassive Black Hole at the Galactic Center and its Orbiting Magnetar Rebecca Rimai Diesing Department of Physics and Astronomy Northwestern University Honors Thesis Advisor: Farhad Zadeh Department of Physics and Astronomy Northwestern University At the center of our galaxy a bright radio source, Sgr A*, coincides with a black hole four million times the mass of our sun. Orbiting Sgr A* at a distance of 3 arc seconds (an estimated 0.1 pc) and rotating with a period of 3.76 s is a magnetar, or pulsar⇠ with an extremely strong magnetic field. This magnetar exhibited an X-ray outburst in April 2013, with enhanced, highly variable radio emission detected 10 months later. In order to better understand the behavior of Sgr A* and the magnetar, we study their intensity variability as a function of both time and frequency. More specifically, we present the results of short (8 minute) and long (7 hour) radio continuum observations, taken using the Jansky Very Large Array (VLA) over multiple epochs during the summer of 2016. We find that Sgr A*’s flux density (a proxy for intensity) is highly variable on an hourly timescale, with a frequency dependence that di↵ers at low (34 GHz) and high (44 GHz) frequencies. We also find that the magnetar remains highly variable on both short (8 min) and long (monthly) timescales, in agreement with observations from 2014.
    [Show full text]
  • A Hidden Population of Exotic Neutron Stars 23 May 2013
    A hidden population of exotic neutron stars 23 May 2013 times stronger than for the average neutron star. New observations show that the magnetar known as SGR 0418+5729 (SGR 0418 for short) doesn't fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars. "We have found that SGR 0418 has a much lower surface magnetic field than any other magnetar," said Nanda Rea of the Institute of Space Science in Barcelona, Spain. "This has important consequences for how we think neutron stars evolve in time, and for our understanding of Credit: X-ray: NASA/CXC/CSIC-IEEC/N.Rea et al; supernova explosions." Optical: Isaac Newton Group of Telescopes, La Palma/WHT; Infrared: NASA/JPL-Caltech; Illustration: The researchers monitored SGR 0418 for over NASA/CXC/M.Weiss three years using Chandra, ESA's XMM-Newton as well as NASA's Swift and RXTE satellites. They were able to make an accurate estimate of the strength of the external magnetic field by (Phys.org) —Magnetars – the dense remains of measuring how its rotation speed changes during dead stars that erupt sporadically with bursts of an X-ray outburst. These outbursts are likely high-energy radiation - are some of the most caused by fractures in the crust of the neutron star extreme objects known in the Universe. A major precipitated by the buildup of stress in a relatively campaign using NASA's Chandra X-ray strong, wound-up magnetic field lurking just Observatory and several other satellites shows beneath the surface. magnetars may be more diverse - and common - than previously thought.
    [Show full text]
  • Massive Fast Rotating Highly Magnetized White Dwarfs: Theory and Astrophysical Applications
    Massive Fast Rotating Highly Magnetized White Dwarfs: Theory and Astrophysical Applications Thesis Advisors Ph.D. Student Prof. Remo Ruffini Diego Leonardo Caceres Uribe* Dr. Jorge A. Rueda *D.L.C.U. acknowledges the financial support by the International Relativistic Astrophysics (IRAP) Ph.D. program. Academic Year 2016–2017 2 Contents General introduction 4 1 Anomalous X-ray pulsars and Soft Gamma-ray repeaters: A new class of pulsars 9 2 Structure and Stability of non-magnetic White Dwarfs 21 2.1 Introduction . 21 2.2 Structure and Stability of non-rotating non-magnetic white dwarfs 23 2.2.1 Inverse b-decay . 29 2.2.2 General Relativity instability . 31 2.2.3 Mass-radius and mass-central density relations . 32 2.3 Uniformly rotating white dwarfs . 37 2.3.1 The Mass-shedding limit . 38 2.3.2 Secular Instability in rotating and general relativistic con- figurations . 38 2.3.3 Pycnonuclear Reactions . 39 2.3.4 Mass-radius and mass-central density relations . 41 3 Magnetic white dwarfs: Stability and observations 47 3.1 Introduction . 47 3.2 Observations of magnetic white dwarfs . 49 3.2.1 Introduction . 49 3.2.2 Historical background . 51 3.2.3 Mass distribution of magnetic white dwarfs . 53 3.2.4 Spin periods of isolated magnetic white dwarfs . 53 3.2.5 The origin of the magnetic field . 55 3.2.6 Applications . 56 3.2.7 Conclusions . 57 3.3 Stability of Magnetic White Dwarfs . 59 3.3.1 Introduction . 59 3.3.2 Ultra-magnetic white dwarfs . 60 3.3.3 Equation of state and virial theorem violation .
    [Show full text]
  • Gamma-Ray Bursts and Magnetars
    GAMMA-RAY BURSTS AND MAGNETARS How USRA scientists helped make major advancements in high-energy astrophysics. During the 1960s, the second Administrator Frank J. Kerr (1918 - 2000) of the University of NASA, James E. Webb, sought a university- of Maryland was appointed by USRA to based organization that could serve the manage its programs in astronomy and needs of NASA as well as the space research astrophysics. Kerr was a highly-regarded radio community. In particular, Webb sought to astronomer, originally from Australia. He had have university researchers assist NASA in been the Director of the Astronomy Program the planning and execution of large, complex at the University projects. The result of Webb’s vision was of Maryland, the Universities Space Research Association and at the time (USRA), which was incorporated as a non- of his USRA proft association of research universities on appointment 12 March 1969. in 1983, he was Provost of As described in the previous essay, USRA’s the Division of frst major collaboration with NASA was the Physical and Apollo Exploration of the Moon. The vehicle Mathematical by which USRA assisted NASA and the space Sciences and research community was the Lunar Science Engineering at Institute, later renamed the Lunar and the University. Frank Kerr Planetary Institute. In support of Another major project was undertaken in MSFC and NRL, USRA brought astronomers 1983, when USRA began to support NASA to work closely with NASA researchers in in the development of the Space Telescope the development of instrumentation and Project at NASA’s Marshall Space Flight the preparation for analyses of data for Center (MSFC).
    [Show full text]
  • Magnetars: Pion Condensates in the Sky?
    Magnetars: Pion Condensates in the Sky? N.D. Hari Dass TIFR-TCIS, Hyderabad In collaboration with V. Soni(Jamia) & Dipankar Bhattacharya(IUCAA) IWARA 2018, Ollantaytambo, Peru. N.D. Hari Dass Magnetars & Pion Condensates Some References N.D. Hari Dass and V. Soni, Mon. Not. Royal Astron. Soc., 425, 1558-1566 (2012). H.B. Nielsen and V. Soni, Phys. Lett. B726, 41-44 (2013). N.D. Hari Dass Magnetars & Pion Condensates Neutron Stars Nuclear density ρ 2:8 1014gm=cm3. Equivalently 0 ' n 0:17nucleons=fermi3. 0 ' Stable neutron stars can have masses in the range 0.1 solar mass to 2 solar masses. Most observed pulsars have masses about 1.4 solar masses. Neutron stars produced in core collapse are expected with this mass. Heavier neutron stars are believed to be as a result of acretion later on. Typical radii of NS are 10 - 20 kms. Neutron stars can be thought of as giant nuclei with A 1057! ' N.D. Hari Dass Magnetars & Pion Condensates Neutron Star Structure Density ρ decreases as one moves outwards from the centre. The outer kilometre or so is the Crust. It consists of a lattice of bare nuclei and a degenerate electron gas. Next to the crust is a superfluid layer and vortices here contribute to the angular momentum of the star. These vortices also play an important role in the so called glitches whence the star actually speeds up. The least understood part is the core of the NS. Density here can be in the range of 3-10 times nuclear density. It is also very hot.
    [Show full text]
  • Search for Neutrino Emission from Fast Radio Bursts with Icecube
    Search for Neutrino Emission from Fast Radio Bursts with IceCube Donglian Xu Samuel Fahey, Justin Vandenbroucke and Ali Kheirandish for the IceCube Collaboration TeV Particle Astrophysics (TeVPA) 2017 August 7 - 11, 2017 | Columbus, Ohio Fast Radio Bursts - Discovery in 2007 2 e2 Lorimer et al.,Science 318 (5851): 777-780 2 ∆tdelay = 3 DM w− 2⇡mec · · 24 2 =1.5 10− s DM w− ⇥ · · 3 DM = n dl = 375 1cm− pc e ± Z “very compact” SMC J0045−7042 (70) J0111−7131 (76) J0113−7220 (125) “extragalactic”? J0045−7319 (105) J0131−7310 (205) Figure 2: Frequency evolution and integrated pulse shape of!the radio burst.4 The.8 survey0.4 data, collected on 2001δ Augusttwidth 24, are=4 shown. here6 ms as a two-dimensio ( nal ‘waterfall)− plot’± of intensity as a function of radio frequency versus time. The dispersion1.4GHzis clearly seen as a quadratic sweep across the frequency band, with broadening towards lower frequencies. From a measurement of the pulse delay across the receiver band using standard pulsar timing techniques, we determine the DM to be 375 dtI1 cm−3!pc. The two150 white lines50Jy separated byms 15 ms @ that 1 bound.4 GHz the pulse show the expected behavior± for the' cold-plasma dispersion± law assuming a DM of 375 cm−3 pc. The horizontal line at 1.34 GHz is an artifact in the data caused by a malfunctioning frequency Z ∼ channel. This plot is for one of the offset beams in which the digitizers were not saturated. By splitting the data into four frequency sub-bands we have measured both the half-power Galactic DM: pulse width• andA fluxtotal density spectrumof ~ over23 the observingFRBs bandwidth.
    [Show full text]
  • Neutron Star Collapse Times, Gamma-Ray Bursts and Fast Radio Bursts
    MNRAS 441, 2433–2439 (2014) doi:10.1093/mnras/stu720 The birth of black holes: neutron star collapse times, gamma-ray bursts and fast radio bursts ‹ Vikram Ravi1,2 and Paul D. Lasky1 Downloaded from https://academic.oup.com/mnras/article-abstract/441/3/2433/1126394 by California Institute of Technology user on 24 June 2019 1School of Physics, University of Melbourne, Parkville, VIC 3010, Australia 2CSIRO Astronomy and Space Science, Australia Telescope National Facility, PO Box 76, Epping, NSW 1710, Australia Accepted 2014 April 8. Received 2014 April 7; in original form 2013 November 29 ABSTRACT Recent observations of short gamma-ray bursts (SGRBs) suggest that binary neutron star (NS) mergers can create highly magnetized, millisecond NSs. Sharp cut-offs in X-ray afterglow plateaus of some SGRBs hint at the gravitational collapse of these remnant NSs to black holes. The collapse of such ‘supramassive’ NSs also describes the blitzar model, a leading candidate for the progenitors of fast radio bursts (FRBs). The observation of an FRB associated with an SGRB would provide compelling evidence for the blitzar model and the binary NS merger scenario of SGRBs, and lead to interesting constraints on the NS equation of state. We predict the collapse times of supramassive NSs created in binary NS mergers, finding that such stars collapse ∼10–4.4 × 104 s (95 per cent confidence) after the merger. This directly impacts observations targeting NS remnants of binary NS mergers, providing the optimal window for high time resolution radio and X-ray follow-up of SGRBs and gravitational wave bursts.
    [Show full text]
  • Magnetar Formation Through a Convective Dynamo in Protoneutron Stars Raphaël Raynaud, Jérôme Guilet, Hans-Thomas Janka, Thomas Gastine
    Magnetar formation through a convective dynamo in protoneutron stars Raphaël Raynaud, Jérôme Guilet, Hans-Thomas Janka, Thomas Gastine To cite this version: Raphaël Raynaud, Jérôme Guilet, Hans-Thomas Janka, Thomas Gastine. Magnetar formation through a convective dynamo in protoneutron stars. Science Advances , American Association for the Advancement of Science (AAAS), 2020, 6 (eaay2732), 10.1126/sciadv.aay2732. hal-02428428 HAL Id: hal-02428428 https://hal.archives-ouvertes.fr/hal-02428428 Submitted on 14 Mar 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. SCIENCE ADVANCES | RESEARCH ARTICLE ASTRONOMY Copyright © 2020 The Authors, some rights reserved; Magnetar formation through a convective dynamo exclusive licensee American Association in protoneutron stars for the Advancement Raphaël Raynaud1*, Jérôme Guilet1, Hans-Thomas Janka2, Thomas Gastine3 of Science. No claim to original U.S. Government Works. Distributed The release of spin-down energy by a magnetar is a promising scenario to power several classes of extreme explosive under a Creative transients. However, it lacks a firm basis because magnetar formation still represents a theoretical challenge. Using Commons Attribution the first three-dimensional simulations of a convective dynamo based on a protoneutron star interior model, we NonCommercial demonstrate that the required dipolar magnetic field can be consistently generated for sufficiently fast rotation License 4.0 (CC BY-NC).
    [Show full text]
  • Giant Sparks at Cosmological Distances?
    The Astrophysical Journal, 797:70 (31pp), 2014 December 10 doi:10.1088/0004-637X/797/1/70 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. GIANT SPARKS AT COSMOLOGICAL DISTANCES? S. R. Kulkarni1,E.O.Ofek2,J.D.Neill3, Z. Zheng4,andM.Juric5 1 Caltech Optical Observatories 249-17, California Institute of Technology, Pasadena, CA 91125, USA 2 Department of Particle Physics & Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel 3 Space Radiation Laboratory 290-17, California Institute of Technology, Pasadena, CA 91125, USA 4 Department of Physics & Astronomy, University of Utah, 115 South 1400 East 201, Salt Lake City, UT 84112, USA 5 Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA Received 2014 February 28; accepted 2014 September 23; published 2014 November 25 ABSTRACT Millisecond-duration bright radio pulses at 1.4 GHz with high dispersion measures (DMs) were reported by Lorimer et al., Keane et al., and Thornton et al. Their all-sky rate is ≈104 day−1 above ∼1 Jy. Related events are “Perytons”—similar pulsed, dispersed sources, but most certainly local. Suggested models of fast radio bursts (FRBs) can originate in Earth’s atmosphere, in stellar coronae, in other galaxies, and even at cosmological distances. Using physically motivated assumptions combined with observed properties, we explore these models. In our analysis, we focus on the Lorimer event: a 30 Jy, 5 ms duration burst with DM = 375 cm−3 pc, exhibiting a steep frequency-dependent pulse width (the Sparker). To be complete, we drop the assumption that high DMs are produced by plasma propagation and assume that the source produces pulses with frequency-dependent arrival time (“chirped signals”).
    [Show full text]