Reva Williams

Last updated
Reva Kay Williams
Nationality American
Education Malcolm X College
A.A. in liberal arts, 1977
Northwestern University
BA in astronomy & physics, 1980
Indiana University Bloomington
MA in astrophysics, 1990
Indiana University Bloomington
Ph.D. in astrophysics, 1991 [1]
Known forFirst person to successfully work out the Penrose process [1]
First Black American woman to receive a PhD in theoretical astrophysics
Frame-dragging
Gravitomagnetism
Scientific career
Fields Astrophysics
Institutions University of Toledo
University of Florida
Bennett College
Thesis Extracting X-rays, gamma rays, and electron-positron pairs from supermassive Kerr black holes using the Penrose mechanism  (1991)
Doctoral advisor Richard H. Durisen

Reva Kay Williams is a theoretical astrophysicist. She is the first person to successfully work out the Penrose process using Einstein's Theory of Relativity to extract energy from black holes. Also, she is the first Black American woman to earn a PhD in theoretical astrophysics. Her work focuses on general relativistic astrophysics.

Contents

Early life and education

Williams was born in Memphis, Tennessee and moved to Chicago at the age of 6. She received an AA in liberal arts from Malcolm X College in 1977 and a BA in astronomy from Northwestern University in 1980. Williams completed both a MA and a PhD at Indiana University Bloomington, and when she completed her degree in 1991 she became the first Black American woman to receive a doctorate in theoretical astrophysics. [1]

Penrose process

With the publication of her PhD thesis in 1991, Williams became the first person to work out the Penrose process of black holes. [2] In 1995, Williams published a paper in Physical Review D of research from her PhD thesis. [3] Her calculations explained that black hole jets are emitted as escaping tornado-like coils of high energy photons and relativistic electrons, and as black holes drag spacetime into rotation near their cores, they may also produce uneven jets. [4] [5]

In April 2004, Williams published a letter titled "A Word from a Black Female Relativistic Astrophysicist: Setting the Record Straight on Black Holes" addressing her experience with breakthrough black hole physics and not receiving appropriate citations and others taking credit for her work. [6]

Postdoctoral career

Williams was the first person to successfully work out the Penrose process, which explains how energy can be extracted from a black hole. Above, a spectacular view of black hole outflows from the radio galaxy Centaurus A. Black Hole Outflows From Centaurus A.jpg
Williams was the first person to successfully work out the Penrose process, which explains how energy can be extracted from a black hole. Above, a spectacular view of black hole outflows from the radio galaxy Centaurus A.

Williams was awarded a National Research Council Ford postdoctoral minority fellowship and was a postdoctoral associate at the University of Florida from 1993 to 1996. [7] [8] In January 1997, she worked as a visiting assistant professor of physics at North Carolina Agricultural and Technical State University (North Carolina A&T), [8] and in 1998, she became an associate professor of astrophysics and director of the Center for Women and Science at Bennett College, remaining in that position until 2001. [8]

In 2000, Williams received a grant to work with Robert M. Hjellming in Aspen, Colorado and Socorro, New Mexico studying microquasars. At that time, she was considered as the only Black American female astrophysicist in the United States, [9] and as of 2004 was one of the few women in the world researching black holes. [10]

In 2009, she was awarded a National Science Foundation grant to "investigate the jet structure and energy generation of quasars and other active galactic nuclei (AGNs), microquasars, and gamma-ray bursters, all of which are believed to be powered by rotating (Kerr) black holes". [11] [12]

Since 2009, Williams has been a research assistant professor at the University of Toledo. [13] [7] Her continuing research interests are relativistic astrophysics, general relativity, cosmology, and extragalactic astronomy. [8]

Williams gave a plenary speech at the astrobiology conference, AbSciCon, in the spring of 2022, organized by American Geophysical Union and NASA. [14]

Selected publications

Related Research Articles

<span class="mw-page-title-main">Quasar</span> Active galactic nucleus containing a supermassive black hole

A quasar is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosities thousands of times greater than that of a galaxy such as the Milky Way. Quasars are usually categorized as a subclass of the more general category of AGN. The redshifts of quasars are of cosmological origin.

Timeline of black hole physics

An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such excess, non-stellar emissions have been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy.

<span class="mw-page-title-main">X-ray binary</span> Class of binary stars

X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the donor, to the other component, called the accretor, which is either a neutron star or black hole. The infalling matter releases gravitational potential energy, up to 30 percent of its rest mass, as X-rays. The lifetime and the mass-transfer rate in an X-ray binary depends on the evolutionary status of the donor star, the mass ratio between the stellar components, and their orbital separation.

<span class="mw-page-title-main">Microquasar</span> Nearby miniature analogue of a quasar

A microquasar, a smaller version of a quasar, is a compact region surrounding a stellar black hole with a mass several times that of its companion star, observable in sufficient details, in our own or nearby galaxy. The matter being pulled from the companion star forms an accretion disk around the black hole. This accretion disk may become so hot, due to friction, that it begins to emit X-rays. The disk also projects narrow streams or "jets" of subatomic particles at near-light speed, generating a strong radio wave emission.

<span class="mw-page-title-main">Messier 87</span> Elliptical galaxy in the Virgo Galaxy Cluster

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.

<span class="mw-page-title-main">Supermassive black hole</span> Largest type of black hole

A supermassive black hole is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions, of times the mass of the Sun (M☉). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, including light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center. For example, the Milky Way galaxy has a supermassive black hole at its center, corresponding to the radio source Sagittarius A*. Accretion of interstellar gas onto supermassive black holes is the process responsible for powering active galactic nuclei (AGNs) and quasars.

<span class="mw-page-title-main">Blazar</span> Very compact quasi-stellar radio source

A blazar is an active galactic nucleus (AGN) with a relativistic jet directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the jet makes blazars appear much brighter than they would be if the jet were pointed in a direction away from Earth. Blazars are powerful sources of emission across the electromagnetic spectrum and are observed to be sources of high-energy gamma ray photons. Blazars are highly variable sources, often undergoing rapid and dramatic fluctuations in brightness on short timescales. Some blazar jets appear to exhibit superluminal motion, another consequence of material in the jet traveling toward the observer at nearly the speed of light.

<span class="mw-page-title-main">Rotating black hole</span> Black hole which possesses angular momentum

A rotating black hole is a black hole that possesses angular momentum. In particular, it rotates about one of its axes of symmetry.

<span class="mw-page-title-main">Astrophysical jet</span> Beam of ionized matter flowing along the axis of a rotating astronomical object

An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as extended beams along the axis of rotation. When this greatly accelerated matter in the beam approaches the speed of light, astrophysical jets become relativistic jets as they show effects from special relativity.

<span class="mw-page-title-main">Penrose process</span> Hypothetical mechanism for extracting energy from rotating black holes

The Penrose process is theorised by Sir Roger Penrose as a means whereby energy can be extracted from a rotating black hole. The process takes advantage of the ergosphere – a region of spacetime around the black hole dragged by its rotation faster than the speed of light, meaning that from the point of view of an outside observer any matter inside is forced to move in the direction of the rotation of the black hole.

<span class="mw-page-title-main">GRS 1915+105</span> Binary system in the constellation Aquila

GRS 1915+105 or V1487 Aquilae is an X-ray binary star system containing a main sequence star and a black hole. Transfer of material from the star to the black hole generates a relativistic jet, making this a microquasar system. The jet exhibits apparent superluminal motion.

<span class="mw-page-title-main">Roger Blandford</span> British theoretical astrophysicist

Roger David Blandford, FRS, FRAS is a British theoretical astrophysicist, best known for his work on black holes.

The Blandford–Znajek process is a mechanism for the extraction of energy from a rotating black hole, introduced by Roger Blandford and Roman Znajek in 1977. This mechanism is the most preferred description of how astrophysical jets are formed around spinning supermassive black holes. This is one of the mechanisms that power quasars, or rapidly accreting supermassive black holes. Generally speaking, it was demonstrated that the power output of the accretion disk is significantly larger than the power output extracted directly from the hole, through its ergosphere. Hence, the presence of a poloidal magnetic field around the black hole is not determinant in its overall power output. It was also suggested that the mechanism plays a crucial role as a central engine for a gamma-ray burst.

<span class="mw-page-title-main">Cloverleaf quasar</span> Rare example of a quadruply-lensed quasar

The Cloverleaf quasar is a bright, gravitationally lensed quasar. It receives its name because of gravitational lensing spitting the single quasar into four images.

<span class="mw-page-title-main">Gravitoelectromagnetism</span> Analogies between Maxwells and Einsteins field equations

Gravitoelectromagnetism, abbreviated GEM, refers to a set of formal analogies between the equations for electromagnetism and relativistic gravitation; specifically: between Maxwell's field equations and an approximation, valid under certain conditions, to the Einstein field equations for general relativity. Gravitomagnetism is a widely used term referring specifically to the kinetic effects of gravity, in analogy to the magnetic effects of moving electric charge. The most common version of GEM is valid only far from isolated sources, and for slowly moving test particles.

Frame-dragging is an effect on spacetime, predicted by Albert Einstein's general theory of relativity, that is due to non-static stationary distributions of mass–energy. A stationary field is one that is in a steady state, but the masses causing that field may be non-static ⁠— rotating, for instance. More generally, the subject that deals with the effects caused by mass–energy currents is known as gravitoelectromagnetism, which is analogous to the magnetism of classical electromagnetism.

<span class="mw-page-title-main">Pictor A</span> Double-lobed radio galaxy in the constellation of Pictor

Pictor A, around 485 million light-years away in the constellation Pictor, is a double-lobed broad-line radio galaxy and a powerful source of radio waves in the Southern Celestial Hemisphere. From a supermassive black hole at its centre, a relativistic jet shoots out to an X-ray hot spot 300,000 light-years away.

<span class="mw-page-title-main">Katherine Blundell</span> Professor of Astrophysics

Katherine Mary Blundell is a Professor of Astrophysics at the University of Oxford and a supernumerary research fellow at St John's College, Oxford. Previously, she held a Royal Society University Research Fellowship, and fellowships from the Royal Commission for the Exhibition of 1851 and Balliol College, Oxford.

Aneta Siemiginowska is a Polish-American astrophysicist whose research involves high-energy cosmic objects including supermassive black hole, quasars, blazars, active galaxies, and astrophysical jets. She works at the Center for Astrophysics | Harvard & Smithsonian as a senior astrophysicist in the Chandra X-ray Center.

References

  1. 1 2 3 Williams, Scott. "Reva Kay Williams". Astronomers of the African Diaspora. Archived from the original on 3 April 2014. Retrieved 21 February 2021.
  2. ↑ Carey, Charles W. (2008). African Americans in Science: An Encyclopedia of People and Progress. ABC-CLIO. ISBN   9781851099986.
  3. ↑ Williams, R. K. (1995). "Extracting x rays, γ rays, and relativistic e−e+ pairs from supermassive Kerr black holes using the Penrose mechanism". Physical Review D. 51 (10): 5387–5427. Bibcode:1995PhRvD..51.5387W. doi:10.1103/PhysRevD.51.5387. PMID   10018300.
  4. ↑ "Astrophysicist Helps Crack A Black Hole Mystery: Energy Jets". University of Florida News. 5 August 2004. Archived from the original on 21 February 2021. Retrieved 21 February 2021.
  5. ↑ Williams, R. K. (2004). "Collimated escaping vortical polar e−e+ jets intrinsically produced by rotating black holes and Penrose processes". The Astrophysical Journal. 611 (2): 952–963. arXiv: astro-ph/0404135 . Bibcode:2004ApJ...611..952W. doi:10.1086/422304. S2CID   1350543.
  6. ↑ Williams, Reva (2004). "A Word from a Black Female Relativistic Astrophysicist: Setting the Record Straight on Black Holes". arXiv: physics/0404029 .
  7. 1 2 "Speakers & Topics". AbSciCon 2022. Archived from the original on 21 February 2021. Retrieved 21 February 2021.
  8. 1 2 3 4 "More about me". revakaywilliams.com. Archived from the original on 24 February 2021. Retrieved 24 February 2021.
  9. ↑ "Professor Wins Science Research Grant". Greensboro News & Record. 17 June 2000. Archived from the original on 23 February 2021. Retrieved 23 February 2021.
  10. ↑ Watson, Wayne D. (4 November 2004). "Alumna Dr. Reva Kay Williams, Malcolm X College" (PDF). City Colleges of Chicago. Archived from the original (PDF) on 21 February 2021. Retrieved 21 February 2021.
  11. ↑ "NSF Award Search: Award#0909098 - Theoretical and Numerical Investigation of a Unified Astrophysical Rotating Black Hole Model for Active Galactic Nuclei, Microquasars, and Gamma-Ray Bursters". www.nsf.gov. Retrieved 2018-11-10.
  12. ↑ "Physics & Astronomy News". www.utoledo.edu. Retrieved 2018-11-10.
  13. ↑ "Research Assistant Professor - Williams, Reva-Kay". www.utoledo.edu. Retrieved 2018-11-10.
  14. ↑ Dr. Reva Kay Williams, "From Supermassive Stars to Quasars: Production of Stardust ...". AbSciCon2022 , retrieved 2023-01-10
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.