Astro2020 Science White Paper Probing the Origin of Our Universe Through Cosmic Microwave Background Constraints on Gravitational Waves
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Measurement of the Speed of Gravity
Measurement of the Speed of Gravity Yin Zhu Agriculture Department of Hubei Province, Wuhan, China Abstract From the Liénard-Wiechert potential in both the gravitational field and the electromagnetic field, it is shown that the speed of propagation of the gravitational field (waves) can be tested by comparing the measured speed of gravitational force with the measured speed of Coulomb force. PACS: 04.20.Cv; 04.30.Nk; 04.80.Cc Fomalont and Kopeikin [1] in 2002 claimed that to 20% accuracy they confirmed that the speed of gravity is equal to the speed of light in vacuum. Their work was immediately contradicted by Will [2] and other several physicists. [3-7] Fomalont and Kopeikin [1] accepted that their measurement is not sufficiently accurate to detect terms of order , which can experimentally distinguish Kopeikin interpretation from Will interpretation. Fomalont et al [8] reported their measurements in 2009 and claimed that these measurements are more accurate than the 2002 VLBA experiment [1], but did not point out whether the terms of order have been detected. Within the post-Newtonian framework, several metric theories have studied the radiation and propagation of gravitational waves. [9] For example, in the Rosen bi-metric theory, [10] the difference between the speed of gravity and the speed of light could be tested by comparing the arrival times of a gravitational wave and an electromagnetic wave from the same event: a supernova. Hulse and Taylor [11] showed the indirect evidence for gravitational radiation. However, the gravitational waves themselves have not yet been detected directly. [12] In electrodynamics the speed of electromagnetic waves appears in Maxwell equations as c = √휇0휀0, no such constant appears in any theory of gravity. -
The Silk Damping Tail of the CMB
The Silk Damping Tail of the CMB 100 K) µ ( T ∆ 10 10 100 1000 l Wayne Hu Oxford, December 2002 Outline • Damping tail of temperature power spectrum and its use as a standard ruler • Generation of polarization through damping • Unveiling of gravitational lensing from features in the damping tail Outline • Damping tail of temperature power spectrum and its use as a standard ruler • Generation of polarization through damping • Unveiling of gravitational lensing from features in the damping tail • Collaborators: Matt Hedman Takemi Okamoto Joe Silk Martin White Matias Zaldarriaga Outline • Damping tail of temperature power spectrum and its use as a standard ruler • Generation of polarization through damping • Unveiling of gravitational lensing from features in the damping tail • Collaborators: Matt Hedman Takemi Okamoto Joe Silk Microsoft Martin White Matias Zaldarriaga http://background.uchicago.edu ("Presentations" in PDF) Damping Tail Photon-Baryon Plasma • Before z~1000 when the CMB had T>3000K, hydrogen ionized • Free electrons act as "glue" between photons and baryons by Compton scattering and Coulomb interactions • Nearly perfect fluid Anisotropy Power Spectrum Damping • Perfect fluid: no anisotropic stresses due to scattering isotropization; baryons and photons move as single fluid Damping • Perfect fluid: no anisotropic stresses due to scattering isotropization; baryons and photons move as single fluid • Fluid imperfections are related to the mean free path of the photons in the baryons −1 λC = τ˙ where τ˙ = neσT a istheconformalopacitytoThomsonscattering -
The Reionization of Cosmic Hydrogen by the First Galaxies Abstract 1
David Goodstein’s Cosmology Book The Reionization of Cosmic Hydrogen by the First Galaxies Abraham Loeb Department of Astronomy, Harvard University, 60 Garden St., Cambridge MA, 02138 Abstract Cosmology is by now a mature experimental science. We are privileged to live at a time when the story of genesis (how the Universe started and developed) can be critically explored by direct observations. Looking deep into the Universe through powerful telescopes, we can see images of the Universe when it was younger because of the finite time it takes light to travel to us from distant sources. Existing data sets include an image of the Universe when it was 0.4 million years old (in the form of the cosmic microwave background), as well as images of individual galaxies when the Universe was older than a billion years. But there is a serious challenge: in between these two epochs was a period when the Universe was dark, stars had not yet formed, and the cosmic microwave background no longer traced the distribution of matter. And this is precisely the most interesting period, when the primordial soup evolved into the rich zoo of objects we now see. The observers are moving ahead along several fronts. The first involves the construction of large infrared telescopes on the ground and in space, that will provide us with new photos of the first galaxies. Current plans include ground-based telescopes which are 24-42 meter in diameter, and NASA’s successor to the Hubble Space Telescope, called the James Webb Space Telescope. In addition, several observational groups around the globe are constructing radio arrays that will be capable of mapping the three-dimensional distribution of cosmic hydrogen in the infant Universe. -
Constraining Stochastic Gravitational Wave Background from Weak Lensing of CMB B-Modes
Prepared for submission to JCAP Constraining stochastic gravitational wave background from weak lensing of CMB B-modes Shabbir Shaikh,y Suvodip Mukherjee,y Aditya Rotti,z and Tarun Souradeepy yInter University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune- 411007, India zDepartment of Physics, Florida State University, Tallahassee, FL 32304, USA E-mail: [email protected], [email protected], [email protected], [email protected] Abstract. A stochastic gravitational wave background (SGWB) will affect the CMB anisotropies via weak lensing. Unlike weak lensing due to large scale structure which only deflects pho- ton trajectories, a SGWB has an additional effect of rotating the polarization vector along the trajectory. We study the relative importance of these two effects, deflection & rotation, specifically in the context of E-mode to B-mode power transfer caused by weak lensing due to SGWB. Using weak lensing distortion of the CMB as a probe, we derive constraints on the spectral energy density (ΩGW ) of the SGWB, sourced at different redshifts, without assuming any particular model for its origin. We present these bounds on ΩGW for different power-law models characterizing the SGWB, indicating the threshold above which observable imprints of SGWB must be present in CMB. arXiv:1606.08862v2 [astro-ph.CO] 20 Sep 2016 Contents 1 Introduction1 2 Weak lensing of CMB by gravitational waves2 3 Method 6 4 Results 8 5 Conclusion9 6 Acknowledgements 10 1 Introduction The Cosmic Microwave Background (CMB) is an exquisite tool to study the universe. It is being used to probe the early universe scenarios as well as the physics of processes happening in between the surface of last scattering and the observer. -
A Brief History of Gravitational Waves
universe Review A Brief History of Gravitational Waves Jorge L. Cervantes-Cota 1, Salvador Galindo-Uribarri 1 and George F. Smoot 2,3,4,* 1 Department of Physics, National Institute for Nuclear Research, Km 36.5 Carretera Mexico-Toluca, Ocoyoacac, C.P. 52750 Mexico, Mexico; [email protected] (J.L.C.-C.); [email protected] (S.G.-U.) 2 Helmut and Ana Pao Sohmen Professor at Large, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077 Hong Kong, China 3 Université Sorbonne Paris Cité, Laboratoire APC-PCCP, Université Paris Diderot, 10 rue Alice Domon et Leonie Duquet, 75205 Paris Cedex 13, France 4 Department of Physics and LBNL, University of California; MS Bldg 50-5505 LBNL, 1 Cyclotron Road Berkeley, 94720 CA, USA * Correspondence: [email protected]; Tel.:+1-510-486-5505 Academic Editors: Lorenzo Iorio and Elias C. Vagenas Received: 21 July 2016; Accepted: 2 September 2016; Published: 13 September 2016 Abstract: This review describes the discovery of gravitational waves. We recount the journey of predicting and finding those waves, since its beginning in the early twentieth century, their prediction by Einstein in 1916, theoretical and experimental blunders, efforts towards their detection, and finally the subsequent successful discovery. Keywords: gravitational waves; General Relativity; LIGO; Einstein; strong-field gravity; binary black holes 1. Introduction Einstein’s General Theory of Relativity, published in November 1915, led to the prediction of the existence of gravitational waves that would be so faint and their interaction with matter so weak that Einstein himself wondered if they could ever be discovered. -
Cosmic Microwave Background
1 29. Cosmic Microwave Background 29. Cosmic Microwave Background Revised August 2019 by D. Scott (U. of British Columbia) and G.F. Smoot (HKUST; Paris U.; UC Berkeley; LBNL). 29.1 Introduction The energy content in electromagnetic radiation from beyond our Galaxy is dominated by the cosmic microwave background (CMB), discovered in 1965 [1]. The spectrum of the CMB is well described by a blackbody function with T = 2.7255 K. This spectral form is a main supporting pillar of the hot Big Bang model for the Universe. The lack of any observed deviations from a 7 blackbody spectrum constrains physical processes over cosmic history at redshifts z ∼< 10 (see earlier versions of this review). Currently the key CMB observable is the angular variation in temperature (or intensity) corre- lations, and to a growing extent polarization [2–4]. Since the first detection of these anisotropies by the Cosmic Background Explorer (COBE) satellite [5], there has been intense activity to map the sky at increasing levels of sensitivity and angular resolution by ground-based and balloon-borne measurements. These were joined in 2003 by the first results from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP)[6], which were improved upon by analyses of data added every 2 years, culminating in the 9-year results [7]. In 2013 we had the first results [8] from the third generation CMB satellite, ESA’s Planck mission [9,10], which were enhanced by results from the 2015 Planck data release [11, 12], and then the final 2018 Planck data release [13, 14]. Additionally, CMB an- isotropies have been extended to smaller angular scales by ground-based experiments, particularly the Atacama Cosmology Telescope (ACT) [15] and the South Pole Telescope (SPT) [16]. -
Gravitational Waves from Supernova Core Collapse Outline Max Planck Institute for Astrophysics, Garching, Germany
Gravitational Waves from Supernova Core Collapse Outline Max Planck Institute for Astrophysics, Garching, Germany Harald Dimmelmeier [email protected] Gravitational Waves from Supernova Core Collapse: What could the Signal tell us? Work done at the MPA in Garching Dimmelmeier, Font, M¨uller, Astron. Astrophys., 388, 917{935 (2002), astro-ph/0204288 Dimmelmeier, Font, M¨uller, Astron. Astrophys., 393, 523{542 (2002), astro-ph/0204289 Source Simulation Focus Session, Center for Gravitational Wave Physics, Penn State University, 2002 Gravitational Waves from Supernova Core Collapse Max Planck Institute for Astrophysics, Garching, Germany Motivation Physics of Core Collapse Supernovæ Physical model of core collapse supernova: Massive progenitor star (Mprogenitor 10 30M ) develops an iron core (Mcore 1:5M ). • ≈ − ≈ This approximate 4/3-polytrope becomes unstable and collapses (Tcollapse 100 ms). • ≈ During collapse, neutrinos are practically trapped and core contracts adiabatically. • At supernuclear density, hot proto-neutron star forms (EoS of matter stiffens bounce). • ) During bounce, gravitational waves are emitted; they are unimportant for collapse dynamics. • Hydrodynamic shock propagates from sonic sphere outward, but stalls at Rstall 300 km. • ≈ Collapse energy is released by emission of neutrinos (Tν 1 s). • ≈ Proto-neutron subsequently cools, possibly accretes matter, and shrinks to final neutron star. • Neutrinos deposit energy behind stalled shock and revive it (delayed explosion mechanism). • Shock wave propagates through -
Secondary Cosmic Microwave Background Anisotropies in A
THE ASTROPHYSICAL JOURNAL, 508:435È439, 1998 December 1 ( 1998. The American Astronomical Society. All rights reserved. Printed in U.S.A. SECONDARY COSMIC MICROWAVE BACKGROUND ANISOTROPIES IN A UNIVERSE REIONIZED IN PATCHES ANDREIGRUZINOV AND WAYNE HU1 Institute for Advanced Study, School of Natural Sciences, Princeton, NJ 08540 Received 1998 March 17; accepted 1998 July 2 ABSTRACT In a universe reionized in patches, the Doppler e†ect from Thomson scattering o† free electrons gener- ates secondary cosmic microwave background (CMB) anisotropies. For a simple model with small patches and late reionization, we analytically calculate the anisotropy power spectrum. Patchy reioniza- tion can, in principle, be the main source of anisotropies on arcminute scales. On larger angular scales, its contribution to the CMB power spectrum is a small fraction of the primary signal and is only barely detectable in the power spectrum with even an ideal, i.e., cosmic variance limited, experiment and an extreme model of reionization. Consequently, patchy reionization is unlikely to a†ect cosmological parameter estimation from the acoustic peaks in the CMB. Its detection on small angles would help determine the ionization history of the universe, in particular, the typical size of the ionized region and the duration of the reionization process. Subject headings: cosmic microwave background È cosmology: theory È intergalactic medium È large-scale structure of universe 1. INTRODUCTION tion below the degree scale. Such e†ects rely on modulating the Doppler e†ect with spatial variations in the optical It is widely believed that the cosmic microwave back- depth. Incarnations of this general mechanism include the ground (CMB) will become the premier laboratory for the Vishniac e†ect from linear density variations (Vishniac study of the early universe and classical cosmology. -
A Brief History of Gravitational Waves
Review A Brief History of Gravitational Waves Jorge L. Cervantes-Cota 1, Salvador Galindo-Uribarri 1 and George F. Smoot 2,3,4,* 1 Department of Physics, National Institute for Nuclear Research, Km 36.5 Carretera Mexico-Toluca, Ocoyoacac, Mexico State C.P.52750, Mexico; [email protected] (J.L.C.-C.); [email protected] (S.G.-U.) 2 Helmut and Ana Pao Sohmen Professor at Large, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, 999077 Kowloon, Hong Kong, China. 3 Université Sorbonne Paris Cité, Laboratoire APC-PCCP, Université Paris Diderot, 10 rue Alice Domon et Leonie Duquet 75205 Paris Cedex 13, France. 4 Department of Physics and LBNL, University of California; MS Bldg 50-5505 LBNL, 1 Cyclotron Road Berkeley, CA 94720, USA. * Correspondence: [email protected]; Tel.:+1-510-486-5505 Abstract: This review describes the discovery of gravitational waves. We recount the journey of predicting and finding those waves, since its beginning in the early twentieth century, their prediction by Einstein in 1916, theoretical and experimental blunders, efforts towards their detection, and finally the subsequent successful discovery. Keywords: gravitational waves; General Relativity; LIGO; Einstein; strong-field gravity; binary black holes 1. Introduction Einstein’s General Theory of Relativity, published in November 1915, led to the prediction of the existence of gravitational waves that would be so faint and their interaction with matter so weak that Einstein himself wondered if they could ever be discovered. Even if they were detectable, Einstein also wondered if they would ever be useful enough for use in science. -
Gravitational Waves and Core-Collapse Supernovae
Gravitational waves and core-collapse supernovae G.S. Bisnovatyi-Kogan(1,2), S.G. Moiseenko(1) (1)Space Research Institute, Profsoyznaya str/ 84/32, Moscow 117997, Russia (2)National Research Nuclear University MEPhI, Kashirskoe shosse 32,115409 Moscow, Russia Abstract. A mechanism of formation of gravitational waves in 1. Introduction the Universe is considered for a nonspherical collapse of matter. Nonspherical collapse results are presented for a uniform spher- On February 11, 2016, LIGO (Laser Interferometric Gravita- oid of dust and a finite-entropy spheroid. Numerical simulation tional-wave Observatory) in the USA with great fanfare results on core-collapse supernova explosions are presented for announced the registration of a gravitational wave (GW) the neutrino and magneto-rotational models. These results are signal on September 14, 2015 [1]. A fantastic coincidence is used to estimate the dimensionless amplitude of the gravita- that the discovery was made exactly 100 years after the tional wave with a frequency m 1300 Hz, radiated during the prediction of GWs by Albert Einstein on the basis of his collapse of the rotating core of a pre-supernova with a mass of theory of General Relativity (GR) (the theory of space and 1:2 M (calculated by the authors in 2D). This estimate agrees time). A detailed discussion of the results of this experiment well with many other calculations (presented in this paper) that and related problems can be found in [2±6]. have been done in 2D and 3D settings and which rely on more Gravitational waves can be emitted by binary stars due to exact and sophisticated calculations of the gravitational wave their relative motion or by collapsing nonspherical bodies. -
Gravitational Wave Echoes from Black Hole Area Quantization
Prepared for submission to JCAP Gravitational wave echoes from black hole area quantization Vitor Cardoso,a;b Valentino F. Foit,c Matthew Klebanc aCentro de Astrofísica e Gravitação - CENTRA, Departamento de Física Instituto Superior Técnico - IST, Universidade de Lisboa, Lisboa, Portugal bTheoretical Physics Department, CERN 1 Esplanade des Particules, Geneva 23, CH-1211, Switzerland cCenter for Cosmology and Particle Physics New York University, New York, USA E-mail: [email protected], [email protected], [email protected] Abstract. Gravitational-wave astronomy has the potential to substantially advance our knowledge of the cosmos, from the most powerful astrophysical engines to the initial stages of our universe. Gravitational waves also carry information about the nature of black holes. Here we investigate the potential of gravitational-wave detectors to test a proposal by Beken- stein and Mukhanov that the area of black hole horizons is quantized in units of the Planck area. Our results indicate that this quantization could have a potentially observable effect on the classical gravitational wave signals received by detectors. In particular, we find distorted gravitational-wave “echoes” in the post-merger waveform describing the inspiral and merger of two black holes. These echoes have a specific frequency content that is characteristic of black hole horizon area quantization. arXiv:1902.10164v1 [hep-th] 26 Feb 2019 Contents 1 Introduction1 1.1 Quantization of black hole area1 1.2 Imprints on classical observables2 1.2.1 Gravitational-wave -
Observational Prospects I Have Cut This Lecture Back to Be Mostly About BAO Because I Still Have Holdover Topics from Previous Lectures to Cover
Precision Cosmology with Large Scale Structure David Weinberg Precision Cosmology With Large Scale Structure David Weinberg, Ohio State University ICTP Cosmology Summer School 2015 Lecture 3: Observational Prospects I have cut this lecture back to be mostly about BAO because I still have holdover topics from previous lectures to cover. Where are we now? CMB Planck: All sky (40,000 deg2), near cosmic-variance limited for temperature anisotropy, noise lim- ited for polarization. ACT and SPT: Higher resolution experiments over smaller areas (hundreds or thousands of deg2), frequency coverage for Sunyaev-Zeldovich as well as primary anisotropy, polarization. Smaller area high-sensitivity experiments for B-mode polarization (e.g., BICEP). Type Ia Supernovae Data sets are compilations of surveys of different redshift ranges, local to z 1.2. ≈ “Compilation” requires enormous effort to bring different data sets to common calibration and analysis. Union 2.1, broad compilation. JLA – local samples, SDSS-II from z = 0.1 0.4, SNLS (Canada-France-Hawaii Telescope) from z = 0.4 1, HST at z > 1. − − Approaching 1000 SNe (740 for JLA). Optical imaging/weak lensing SDSS – 104 deg2, 5 bands (ugriz), depth r 22, weak lensing source density approximately − 1 arcmin 2; SDSS “Stripe 82” went 2 magnitudes≈ deeper over 200 deg2 Pan-STARRS – 3 104 deg2, depth comparable to SDSS × CFHTLens – 150 deg2, Dark Energy Survey (DES) is ongoing, discussed at the end. Redshift surveys SDSS-I/II: 106 galaxies, broadly selected, median z = 0.1 ; 105 luminous red galaxies (LRGs) sparsely sampling structure to z = 0.45 SDSS-III BOSS: 1.5 106 luminous galaxies, z = 0.2 0.7, 7 effective volume of SDSS-I/II LRGs; spectra of 160,000 quasars× at z = 2 4 for Lyα forest− analysis× − Clusters Variety of cluster catalogs selected by different methods.