DOCSLIB.ORG

Some Theoretical Aspects of Magnetars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Some Theoretical Aspects of Magnetars Some theoretical aspects of Magnetars Monika Sinha Indian Institute of Technology Jodhpur Collaborator Armen Sedrakian (Frankfurt Institute of Advanced Studies) Structure of Neutron star Outer crust: ions + electrons a few hundred meters Inner crust: electrons + neutrons + neutron rich nuclei about one kilometer Outer core: neutrons + protons + electrons + muons Inner core: ? number of possibilities Structure of Neutron star Nuclear matter Hyperon matter Pion condensate Kaon condendate Quark matter Neutrons in the core could also be in superfluid state. Theoretical model predicts . Pulsating stars discovered – . Typical radius of NS is ~ 10 km and PULSARS with pulse period ~ ms – s. mass ~ 1.4 Msun: very compact. As NSs are very compact in size, . Radiation from such object is they can withstand fast rotation: emitted in some particular P ~ ms – s. direction. The object is rotating What is the cause of directional radiation? . When radiation comes into Magnetic field our line of sight we observe the radiation. • Hence, pulsars are soon identified as magnetized rotating NS • Pulsars are believed to be rotating NS with surface magnetic field 108 – 1012 G. • Later on NSs were discovered with much higher surface magnetic field 1014 – 1015 G: MAGNETAR Introduction Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) : Very different from ordinary X-ray bursters and pulsars 45 35 • Lpeak ~ 10 ergs/s, Lx ~ 10 ergs/s. • Rotational period ~ 5 – 10 s, spin down rate ~ 10-11 s/s • No evidence of binary companions: sometime association with supernova remnants: Increasing number of common properties: Close relationship between SGRs and AXPs Introduction Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) : Very different from ordinary X-ray bursters and pulsars • No correlation between energy and time interval since the previous burst: Trigger of the bursts is not accretion. • AXPs: Softer spectrum: Neither accretion powered, nor rotation powered. • Current model: Magnetar – Neutron stars with strong surface magnetic field ~ 1014 - 1015 G. • The field in the interior of the NS may have higher value. Effect of magnetic field on matter Energy momentum tensor of the system: Matter energy density Thermodynamic pressure Magnetization tensor Effect of magnetic field on matter • In the rest frame of matter, with the choice of magnetic field Magnetic field Magnetization Effect of magnetic field on matter k p p contribution from potential energy pF In absence of E d 3 p E p2 m2 magnetic field k p p 0 In presence of magnetic field Superconductivity inside neutron stars 14 15 • Bs = 10 -10 G • Interior field even greater Superconductivity inside magnetar Quenched? Superconductivity inside neutron stars Type-II superconductivity London’s penetration δ퐿 depth 1 휅 = κ > ξ푝 √2 Coherence length Type-II superconductivity exists if Φ0 퐻푐2 = 2 Quantum 퐻푐1 < 퐵 < 퐻푐2 2πξ푝 of flux 푛ℎ Φ = 0 2푒 From virial theorem 퐵 > 퐻 18 푚푎푥 푐2 퐵푚푎푥 = 10 G Inputs… 퐸 퐴 = −16.14 MeV 퐸푠 = 32.20 MeV 퐾0 = 250.90 MeV -3 푛0 = 0.152 fm Wambach et al. NPA 555, 128 (1993) Baldo et al. PRC 58, 1921 (1998) Superconductivity inside neutron stars ΦΦ00 퐻푐2 = 2 1 + 푓 2πξ푝 푘푝 ξ푝 = π푚푒푓푓Δ푝 2 2 2 27π 푛푛 Δ푝 푓 = 퐺푛푝 2 2 8 μ푝 μ푛 푚푝푘퐹푝 16 max 퐻푐2 ≅ 6.25 × 10 G Implications… Field Rotational Neutrino decay dynamics emissivity glitch cooling Reheating Heat capacity Electrical conductivity Emissivity 풌푭풏 푛 → 푝 + 푒 + ν 푒 풌푭풑 풌푭풆 푘 2 − (푘 + 푘 )2 Direct Urca 퐹푛 퐹푝 퐹푒 2/3 푥 = 2 푁퐹푝 process 푘퐹푛 Pair-breaking process Neutrino emissivity Neutrino dUrca emissivity −(Δ +Δ ) 푇 푒 푛 푝 푥 > 0 푥 < 0 Pair-breaking emissivity 4퐺 2 ϵ = =푎 푆/푃(퐵) 퐹 푇7퓘 푛/푝 푛/푝 15π2 Summary • Presence of magnetic field introduces the anisotropic pressure in the system. • Negative contribution from field pressure of from interaction of matter with field to pressure leads to instability above a critical field. • Magnetars are fully of partially free of proton superconductivity depending on strength of field inside the magnetars. • Neutrino emissivity is affected due to unpairing effect. • Detailed cooling simulations are needed to confront the theory of magnetar with quenched superconductivity with the observations. • Heat capacity, reheating due to field decay are to be addressed under this condition. • Electrical conductivity, field decay, rotational dynamic, coupling of normal matter to superfluid matter should be revisited with this result. .
Load more

Recommended publications
  • Negreiros Lecture II
    General Relativity and Neutron Stars - II Rodrigo Negreiros – UFF - Brazil Outline • Compact Stars • Spherically Symmetric • Rotating Compact Stars • Magnetized Compact Stars References for this lecture Compact Stars • Relativistic stars with inner structure • We need to solve Einstein’s equation for the interior as well as the exterior Compact Stars - Spherical • We begin by writing the following metric • Which leads to the following components of the Riemman curvature tensor Compact Stars - Spherical • The Ricci tensor components are calculated as • Ricci scalar is given by Compact Stars - Spherical • Now we can calculate Einstein’s equation as 휇 • Where we used a perfect fluid as sources ( 푇휈 = 푑푖푎푔(휖, 푃, 푃, 푃)) Compact Stars - Spherical • Einstein’s equation define the space-time curvature • We must also enforce energy-momentum conservation • This implies that • Where the four velocity is given by • After some algebra we get Compact Stars - Spherical • Making use of Euler’s equation we get • Thus • Which we can rewrite as Compact Stars - Spherical • Now we introduce • Which allow us to integrate one of Einstein’s equation, leading to • After some shuffling of Einstein’s equation we can write Summary so far... Metric Energy-Momentum Tensor Einstein’s equation Tolmann-Oppenheimer-Volkoff eq. Relativistic Hydrostatic Equilibrium Mass continuity Stellar structure calculation Microscopic Ewuation of State Macroscopic Composition Structure Recapitulando … “Feed” with diferente microscopic models Microscopic Ewuation of State Macroscopic Composition Structure Compare predicted properties with Observed data. Rotating Compact Stars • During its evolution, compact stars may acquire high rotational frequencies (possibly up to 500 hz) • Rotation breaks spherical symmetry, increasing the degrees of freedom.
    [Show full text]
  • Exploring Pulsars
    High-energy astrophysics Explore the PUL SAR menagerie Astronomers are discovering many strange properties of compact stellar objects called pulsars. Here’s how they fit together. by Victoria M. Kaspi f you browse through an astronomy book published 25 years ago, you’d likely assume that astronomers understood extremely dense objects called neutron stars fairly well. The spectacular Crab Nebula’s central body has been a “poster child” for these objects for years. This specific neutron star is a pulsar that I rotates roughly 30 times per second, emitting regular appar- ent pulsations in Earth’s direction through a sort of “light- house” effect as the star rotates. While these textbook descriptions aren’t incorrect, research over roughly the past decade has shown that the picture they portray is fundamentally incomplete. Astrono- mers know that the simple scenario where neutron stars are all born “Crab-like” is not true. Experts in the field could not have imagined the variety of neutron stars they’ve recently observed. We’ve found that bizarre objects repre- sent a significant fraction of the neutron star population. With names like magnetars, anomalous X-ray pulsars, soft gamma repeaters, rotating radio transients, and compact Long the pulsar poster child, central objects, these bodies bear properties radically differ- the Crab Nebula’s central object is a fast-spinning neutron star ent from those of the Crab pulsar. Just how large a fraction that emits jets of radiation at its they represent is still hotly debated, but it’s at least 10 per- magnetic axis. Astronomers cent and maybe even the majority.
    [Show full text]
  • Neutron Stars
    Chandra X-Ray Observatory X-Ray Astronomy Field Guide Neutron Stars Ordinary matter, or the stuff we and everything around us is made of, consists largely of empty space. Even a rock is mostly empty space. This is because matter is made of atoms. An atom is a cloud of electrons orbiting around a nucleus composed of protons and neutrons. The nucleus contains more than 99.9 percent of the mass of an atom, yet it has a diameter of only 1/100,000 that of the electron cloud. The electrons themselves take up little space, but the pattern of their orbit defines the size of the atom, which is therefore 99.9999999999999% Chandra Image of Vela Pulsar open space! (NASA/PSU/G.Pavlov et al. What we perceive as painfully solid when we bump against a rock is really a hurly-burly of electrons moving through empty space so fast that we can't see—or feel—the emptiness. What would matter look like if it weren't empty, if we could crush the electron cloud down to the size of the nucleus? Suppose we could generate a force strong enough to crush all the emptiness out of a rock roughly the size of a football stadium. The rock would be squeezed down to the size of a grain of sand and would still weigh 4 million tons! Such extreme forces occur in nature when the central part of a massive star collapses to form a neutron star. The atoms are crushed completely, and the electrons are jammed inside the protons to form a star composed almost entirely of neutrons.
    [Show full text]
  • 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]
  • R-Process Elements from Magnetorotational Hypernovae
    r-Process elements from magnetorotational hypernovae D. Yong1,2*, C. Kobayashi3,2, G. S. Da Costa1,2, M. S. Bessell1, A. Chiti4, A. Frebel4, K. Lind5, A. D. Mackey1,2, T. Nordlander1,2, M. Asplund6, A. R. Casey7,2, A. F. Marino8, S. J. Murphy9,1 & B. P. Schmidt1 1Research School of Astronomy & Astrophysics, Australian National University, Canberra, ACT 2611, Australia 2ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia 3Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield, AL10 9AB, UK 4Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA 5Department of Astronomy, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden 6Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85741 Garching, Germany 7School of Physics and Astronomy, Monash University, VIC 3800, Australia 8Istituto NaZionale di Astrofisica - Osservatorio Astronomico di Arcetri, Largo Enrico Fermi, 5, 50125, Firenze, Italy 9School of Science, The University of New South Wales, Canberra, ACT 2600, Australia Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis1–3. However, in Galactic chemical evolution models, neutron-star mergers alone cannot reproduce the observed element abundance patterns of extremely metal-poor stars, which indicates the existence of other sites of r-process nucleosynthesis4–6. These sites may be investigated by studying the element abundance patterns of chemically primitive stars in the halo of the Milky Way, because these objects retain the nucleosynthetic signatures of the earliest generation of stars7–13.
    [Show full text]
  • Introduction to Astronomy from Darkness to Blazing Glory
    Introduction to Astronomy From Darkness to Blazing Glory Published by JAS Educational Publications Copyright Pending 2010 JAS Educational Publications All rights reserved. Including the right of reproduction in whole or in part in any form. Second Edition Author: Jeffrey Wright Scott Photographs and Diagrams: Credit NASA, Jet Propulsion Laboratory, USGS, NOAA, Aames Research Center JAS Educational Publications 2601 Oakdale Road, H2 P.O. Box 197 Modesto California 95355 1-888-586-6252 Website: http://.Introastro.com Printing by Minuteman Press, Berkley, California ISBN 978-0-9827200-0-4 1 Introduction to Astronomy From Darkness to Blazing Glory The moon Titan is in the forefront with the moon Tethys behind it. These are two of many of Saturn’s moons Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA 2 Introduction to Astronomy Contents in Brief Chapter 1: Astronomy Basics: Pages 1 – 6 Workbook Pages 1 - 2 Chapter 2: Time: Pages 7 - 10 Workbook Pages 3 - 4 Chapter 3: Solar System Overview: Pages 11 - 14 Workbook Pages 5 - 8 Chapter 4: Our Sun: Pages 15 - 20 Workbook Pages 9 - 16 Chapter 5: The Terrestrial Planets: Page 21 - 39 Workbook Pages 17 - 36 Mercury: Pages 22 - 23 Venus: Pages 24 - 25 Earth: Pages 25 - 34 Mars: Pages 34 - 39 Chapter 6: Outer, Dwarf and Exoplanets Pages: 41-54 Workbook Pages 37 - 48 Jupiter: Pages 41 - 42 Saturn: Pages 42 - 44 Uranus: Pages 44 - 45 Neptune: Pages 45 - 46 Dwarf Planets, Plutoids and Exoplanets: Pages 47 -54 3 Chapter 7: The Moons: Pages: 55 - 66 Workbook Pages 49 - 56 Chapter 8: Rocks and Ice:
    [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]
  • Luminous Blue Variables
    Review Luminous Blue Variables Kerstin Weis 1* and Dominik J. Bomans 1,2,3 1 Astronomical Institute, Faculty for Physics and Astronomy, Ruhr University Bochum, 44801 Bochum, Germany 2 Department Plasmas with Complex Interactions, Ruhr University Bochum, 44801 Bochum, Germany 3 Ruhr Astroparticle and Plasma Physics (RAPP) Center, 44801 Bochum, Germany Received: 29 October 2019; Accepted: 18 February 2020; Published: 29 February 2020 Abstract: Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or h Car analogs and the S Dor cycle LBVs.
    [Show full text]
  • The Sun, Yellow Dwarf Star at the Heart of the Solar System NASA.Gov, Adapted by Newsela Staff
    Name: ______________________________ Period: ______ Date: _____________ Article of the Week Directions: Read the following article carefully and annotate. You need to include at least 1 annotation per paragraph. Be sure to include all of the following in your total annotations. Annotation = Marking the Text + A Note of Explanation 1. Great Idea or Point – Write why you think it is a good idea or point – ! 2. Confusing Point or Idea – Write a question to ask that might help you understand – ? 3. Unknown Word or Phrase – Circle the unknown word or phrase, then write what you think it might mean based on context clues or your word knowledge – 4. A Question You Have – Write a question you have about something in the text – ?? 5. Summary – In a few sentences, write a summary of the paragraph, section, or passage – # The sun, yellow dwarf star at the heart of the solar system NASA.gov, adapted by Newsela staff Picture and Caption ___________________________ ___________________________ ___________________________ Paragraph #1 ___________________________ ___________________________ This image shows an enormous eruption of solar material, called a coronal mass ejection, spreading out into space, captured by NASA's Solar Dynamics ___________________________ Observatory on January 8, 2002. Paragraph #2 Para #1 The sun is a hot ball made of glowing gases and is a type ___________________________ of star known as a yellow dwarf. It is at the heart of our solar system. ___________________________ Para #2 The solar system consists of everything that orbits the ___________________________ sun. The sun's gravity holds the solar system together, by keeping everything from planets to bits of dust in its orbit.
    [Show full text]
  • Rev 06/2018 ASTRONOMY EXAM CONTENT OUTLINE the Following
    ASTRONOMY EXAM INFORMATION CREDIT RECOMMENDATIONS This exam was developed to enable schools to award The American Council on Education’s College credit to students for knowledge equivalent to that learned Credit Recommendation Service (ACE CREDIT) by students taking the course. This examination includes has evaluated the DSST test development history of the Science of Astronomy, Astrophysics, process and content of this exam. It has made the Celestial Systems, the Science of Light, Planetary following recommendations: Systems, Nature and Evolution of the Sun and Stars, Galaxies and the Universe. Area or Course Equivalent: Astronomy Level: 3 Lower Level Baccalaureate The exam contains 100 questions to be answered in 2 Amount of Credit: 3 Semester Hours hours. Some of these are pretest questions that will not Minimum Score: 400 be scored. Source: www.acenet.edu Form Codes: SQ500, SR500 EXAM CONTENT OUTLINE The following is an outline of the content areas covered in the examination. The approximate percentage of the examination devoted to each content area is also noted. I. Introduction to the Science of Astronomy – 5% a. Nature and methods of science b. Applications of scientific thinking c. History of early astronomy II. Astrophysics - 15% a. Kepler’s laws and orbits b. Newtonian physics and gravity c. Relativity III. Celestial Systems – 10% a. Celestial motions b. Earth and the Moon c. Seasons, calendar and time keeping IV. The Science of Light – 15% a. The electromagnetic spectrum b. Telescopes and the measurement of light c. Spectroscopy d. Blackbody radiation V. Planetary Systems: Our Solar System and Others– 20% a. Contents of our solar system b.
    [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]