Neutron Stars, Pulsars, and Black Holes
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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. -
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. -
Brochure Pulsar Multifunction Spectroscopy Service Complete Cased Hole Formation Evaluation and Reservoir Saturation Monitoring from A
Pulsar Multifunction spectroscopy service Introducing environment-independent, stand-alone cased hole formation evaluation and saturation monitoring 1 APPLICATIONS FEATURES AND BENEFITS ■ Stand-alone formation evaluation for diagnosis of bypassed ■ Environment-independent reservoir saturation monitoring ■ High-performance pulsed neutron generator (PNG) hydrocarbons, depleted reservoirs, and gas zones in any formation water salinity ● Optimized pulsing scheme with multiple square and short ● Differentiation of gas-filled porosity from very low porosity ● Production fluid profile determination for any well pulses for clean separation in measuring both inelastic and formations by using neutron porosity and fast neutron cross inclination: horizontal, deviated, and vertical capture gamma rays 8 section (FNXS) measurements ● Detection of water entry and flow behind casing ● High neutron output of 3.5 × 10 neutron/s for greater ■ measurement precision Petrophysical evaluation with greater accuracy by accounting ● Gravel-pack quality determination by using for grain density and mineral properties in neutron porosity elemental spectroscopy ■ State-of-the-art detectors ■ Total organic carbon (TOC) quantified as the difference ■ Metals for mining exploration ● Near and far detectors: cerium-doped lanthanum bromide between the measured total carbon and inorganic carbon ■ High-resolution determination of reservoir quality (RQ) (LaBr3:Ce) ■ Oil volume from TOC and completion quality (CQ) for formation evaluation ● Deep detector: yttrium aluminum perovskite -
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. -
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. -
College of San Mateo Observatory Stellar Spectra Catalog ______
College of San Mateo Observatory Stellar Spectra Catalog SGS Spectrograph Spectra taken from CSM observatory using SBIG Self Guiding Spectrograph (SGS) ___________________________________________________ A work in progress compiled by faculty, staff, and students. Stellar Spectroscopy Stars are divided into different spectral types, which result from varying atomic-level activity on the star, due to its surface temperature. In spectroscopy, we measure this activity via a spectrograph/CCD combination, attached to a moderately sized telescope. The resultant data are converted to graphical format for further analysis. The main spectral types are characterized by the letters O,B,A,F,G,K, & M. Stars of O type are the hottest, as well as the rarest. Stars of M type are the coolest, and by far, the most abundant. Each spectral type is also divided into ten subtypes, ranging from 0 to 9, further delineating temperature differences. Type Temperature Color O 30,000 - 60,000 K Blue B 10,000 - 30,000 K Blue-white A 7,500 - 10,000 K White F 6,000 - 7,500 K Yellow-white G 5,000 - 6,000 K Yellow K 3,500 - 5,000 K Yellow-orange M >3,500 K Red Class Spectral Lines O -Weak neutral and ionized Helium, weak Hydrogen, a relatively smooth continuum with very few absorption lines B -Weak neutral Helium, stronger Hydrogen, an otherwise relatively smooth continuum A -No Helium, very strong Hydrogen, weak CaII, the continuum is less smooth because of weak ionized metal lines F -Strong Hydrogen, strong CaII, weak NaI, G-band, the continuum is rougher because of many ionized metal lines G -Weaker Hydrogen, strong CaII, stronger NaI, many ionized and neutral metals, G-band is present K -Very weak Hydrogen, strong CaII, strong NaI and many metals G- band is present M -Strong TiO molecular bands, strongest NaI, weak CaII very weak Hydrogen absorption. -
Hawking Radiation
a brief history of andreas müller student seminar theory group max camenzind lsw heidelberg mpia & lsw january 2004 http://www.lsw.uni-heidelberg.de/users/amueller talktalk organisationorganisation basics ☺ standard knowledge advanced knowledge edge of knowledge and verifiability mindmind mapmap whatwhat isis aa blackblack hole?hole? black escape velocity c hole singularity in space-time notion „black hole“ from relativist john archibald wheeler (1968), but first speculation from geologist and astronomer john michell (1783) ☺ blackblack holesholes inin relativityrelativity solutions of the vacuum field equations of einsteins general relativity (1915) Gµν = 0 some history: schwarzschild 1916 (static, neutral) reissner-nordstrøm 1918 (static, electrically charged) kerr 1963 (rotating, neutral) kerr-newman 1965 (rotating, charged) all are petrov type-d space-times plug-in metric gµν to verify solution ;-) ☺ black hole mass hidden in (point or ring) singularity blackblack holesholes havehave nono hairhair!! schwarzschild {M} reissner-nordstrom {M,Q} kerr {M,a} kerr-newman {M,a,Q} wheeler: no-hair theorem ☺ blackblack holesholes –– schwarzschildschwarzschild vs.vs. kerrkerr ☺ blackblack holesholes –– kerrkerr inin boyerboyer--lindquistlindquist black hole mass M spin parameter a lapse function delta potential generalized radius sigma potential frame-dragging frequency cylindrical radius blackblack holehole topologytopology blackblack holehole –– characteristiccharacteristic radiiradii G = M = c = 1 blackblack holehole -- -
Scattering on Compact Body Spacetimes
Scattering on compact body spacetimes Thomas Paul Stratton A thesis submitted for the degree of Doctor of Philosophy School of Mathematics and Statistics University of Sheffield March 2020 Summary In this thesis we study the propagation of scalar and gravitational waves on compact body spacetimes. In particular, we consider spacetimes that model neutron stars, black holes, and other speculative exotic compact objects such as black holes with near horizon modifications. We focus on the behaviour of time-independent perturbations, and the scattering of plane waves. First, we consider scattering by a generic compact body. We recap the scattering theory for scalar and gravitational waves, using a metric perturbation formalism for the latter. We derive the scattering and absorption cross sections using the partial-wave approach, and discuss some approximations. The theory of this chapter is applied to specific examples in the remainder of the thesis. The next chapter is an investigation of scalar plane wave scattering by a constant density star. We compute the scattering cross section numerically, and discuss a semiclassical, high-frequency analysis, as well as a geometric optics approach. The semiclassical results are compared to the numerics, and used to gain some physical insight into the scattering cross section interference pattern. We then generalise to stellar models with a polytropic equation of state, and gravitational plane wave scattering. This entails solving the metric per- turbation problem for the interior of a star, which we accomplish numerically. We also consider the near field scattering profile for a scalar wave, and the cor- respondence to ray scattering and the formation of a downstream cusp caustic. -
Chapter 22 Neutron Stars and Black Holes Units of Chapter 22 22.1 Neutron Stars 22.2 Pulsars 22.3 Xxneutron-Star Binaries: X-Ray Bursters
Chapter 22 Neutron Stars and Black Holes Units of Chapter 22 22.1 Neutron Stars 22.2 Pulsars 22.3 XXNeutron-Star Binaries: X-ray bursters [Look at the slides and the pictures in your book, but I won’t test you on this in detail, and we may skip altogether in class.] 22.4 Gamma-Ray Bursts 22.5 Black Holes 22.6 XXEinstein’s Theories of Relativity Special Relativity 22.7 Space Travel Near Black Holes 22.8 Observational Evidence for Black Holes Tests of General Relativity Gravity Waves: A New Window on the Universe Neutron Stars and Pulsars (sec. 22.1, 2 in textbook) 22.1 Neutron Stars According to models for stellar explosions: After a carbon detonation supernova (white dwarf in binary), little or nothing remains of the original star. After a core collapse supernova, part of the core may survive. It is very dense—as dense as an atomic nucleus—and is called a neutron star. [Recall that during core collapse the iron core (ashes of previous fusion reactions) is disintegrated into protons and neutrons, the protons combine with the surrounding electrons to make more neutrons, so the core becomes pure neutron matter. Because of this, core collapse can be halted if the core’s mass is between 1.4 (the Chandrasekhar limit) and about 3-4 solar masses, by neutron degeneracy.] What do you get if the core mass is less than 1.4 solar masses? Greater than 3-4 solar masses? 22.1 Neutron Stars Neutron stars, although they have 1–3 solar masses, are so dense that they are very small. -
CHIME and Probing the Origin of Fast Radio Bursts by Liam Dean Connor a Thesis Submitted in Conformity with the Requirements
CHIME and Probing the Origin of Fast Radio Bursts by Liam Dean Connor A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Astronomy and Astrophysics University of Toronto c Copyright 2016 by Liam Dean Connor Abstract CHIME and Probing the Origin of Fast Radio Bursts Liam Dean Connor Doctor of Philosophy Graduate Department of Astronomy and Astrophysics University of Toronto 2016 The time-variable long-wavelength sky harbours a number of known but unsolved astro- physical problems, and surely many more undiscovered phenomena. With modern tools such problems will become tractable, and new classes of astronomical objects will be revealed. These tools include digital telescopes made from powerful computing clusters, and improved theoretical methods. In this thesis we employ such devices to understand better several puzzles in the time-domain radio sky. Our primary focus is on the origin of fast radio bursts (FRBs), a new class of transients of which there seem to be thousands per sky per day. We offer a model in which FRBs are extragalactic but non-cosmological pulsars in young supernova remnants. Since this theoretical work was done, observations have corroborated the picture of FRBs as young rotating neutron stars, including the non-Poissonian repetition of FRB 121102. We also present statistical arguments regard- ing the nature and location of FRBs. These include reinstituting the classic V=Vmax-test @ log N to measure the brightness distribution of FRBs, i.e., constraining @ log S . We find consis- tency with a Euclidean distribution. This means current observations cannot distinguish between a cosmological population and a more local uniform population, unless added assumptions are made. -
Binary Star Modeling: a Computational Approach
TCNJ JOURNAL OF STUDENT SCHOLARSHIP VOLUME XIV APRIL 2012 BINARY STAR MODELING: A COMPUTATIONAL APPROACH Author: Daniel Silano Faculty Sponsor: R. J. Pfeiffer, Department of Physics ABSTRACT This paper illustrates the equations and computational logic involved in writing BinaryFactory, a program I developed in Spring 2011 in collaboration with Dr. R. J. Pfeiffer, professor of physics at The College of New Jersey. This paper outlines computational methods required to design a computer model which can show an animation and generate an accurate light curve of an eclipsing binary star system. The final result is a light curve fit to any star system using BinaryFactory. An example is given for the eclipsing binary star system TU Muscae. Good agreement with observational data was obtained using parameters obtained from literature published by others. INTRODUCTION This project started as a proposal for a simple animation of two stars orbiting one another in C++. I found that although there was software that generated simple animations of binary star orbits and generated light curves, the commercial software was prohibitively expensive or not very user friendly. As I progressed from solving the orbits to generating the Roche surface to generating a light curve, I learned much about computational physics. There were many trials along the way; this paper aims to explain to the reader how a computational model of binary stars is made, as well as how to avoid pitfalls I encountered while writing BinaryFactory. Binary Factory was written in C++ using the free C++ libraries, OpenGL, GLUT, and GLUI. A basis for writing a model similar to BinaryFactory in any language will be presented, with a light curve fit for the eclipsing binary star system TU Muscae in the final secion. -
De-Coding Starlight (Grades 5-8)
Teacher's Guide to Chandra X-ray Observatory From Pixels to Images: De-Coding Starlight (Grades 5-8) Background and Purpose In an effort to learn more about black holes, pulsars, supernovas, and other high-energy astronomical events, NASA launched the Chandra X-ray Observatory in 1999. Chandra is the largest space telescope ever launched and detects "invisible" X-ray radiation, which is often the only way that scientists can pinpoint and understand high-energy events in our universe. Computer aided data collection and processing is an essential facet to astronomical research using space- and ground-based telescopes. Every 8 hours, Chandra downloads millions of pieces of information to Earth. To control, process, and analyze this flood of numbers, scientists rely on computers, not only to do calculations, but also to change numbers into pictures. The final results of these analyses are wonderful and exciting images that expand understanding of the universe for not only scientists, but also decision-makers and the general public. Although computers are used extensively, scientists and programmers go through painstaking calibration and validation processes to ensure that computers produce technically correct images. As Dr. Neil Comins so eloquently states1, “These images create an impression of the glamour of science in the public mind that is not entirely realistic. The process of transforming [i.e., by using computers] most telescope data into accurate and meaningful images is long, involved, unglamorous, and exacting. Make a mistake in one of dozens of parameters or steps in the analysis and you will get inaccurate results.” The process of making the computer-generated images from X-ray data collected by Chandra involves the use of "false color." X-rays cannot be seen by human eyes, and therefore, have no "color." Visual representation of X-ray data, as well as radio, infrared, ultraviolet, and gamma, involves the use of "false color" techniques, where colors in the image represent intensity, energy, temperature, or another property of the radiation.