What Does a Black Hole Look Like?

What Does a Black Hole Look Like?

CHARLES D. BAILYN
Copyright Date: 2014
Edition: STU - Student edition
Pages: 224
https://www.jstor.org/stable/j.ctt6wq0ft
  • Cite this Item
  • Book Info
    What Does a Black Hole Look Like?
    Book Description:

    Emitting no radiation or any other kind of information, black holes mark the edge of the universe--both physically and in our scientific understanding. Yet astronomers have found clear evidence for the existence of black holes, employing the same tools and techniques used to explore other celestial objects. In this sophisticated introduction, leading astronomer Charles Bailyn goes behind the theory and physics of black holes to describe how astronomers are observing these enigmatic objects and developing a remarkably detailed picture of what they look like and how they interact with their surroundings.

    Accessible to undergraduates and others with some knowledge of introductory college-level physics, this book presents the techniques used to identify and measure the mass and spin of celestial black holes. These key measurements demonstrate the existence of two kinds of black holes, those with masses a few times that of a typical star, and those with masses comparable to whole galaxies--supermassive black holes. The book provides a detailed account of the nature, formation, and growth of both kinds of black holes. The book also describes the possibility of observing theoretically predicted phenomena such as gravitational waves, wormholes, and Hawking radiation.

    A cutting-edge introduction to a subject that was once on the border between physics and science fiction, this book shows how black holes are becoming routine objects of empirical scientific study.

    eISBN: 978-1-4008-5056-3
    Subjects: Physics

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
  3. PREFACE
    (pp. xi-xiv)
  4. 1 INTRODUCING BLACK HOLES: EVENT HORIZONS AND SINGULARITIES
    (pp. 1-12)

    Black holes are extraordinary objects. They exert an attractive force that nothing can withstand; they stop time, turn space inside out, and constitute a point of no return beyond which our universe comes to an end. They address issues that have always fascinated humans—literature and philosophy in all times and cultures explore irresistible lures, the limits of the universe, and the nature of time and space. In our own time and place, science has become a dominant force both intellectually and technologically, and the scientific manifestation of these ancient themes provides a powerful metaphor that has come to permeate...

  5. 2 ACCRETION ONTO A BLACK HOLE
    (pp. 13-42)

    One might think that it would be difficult to observe black holes, given that their defining characteristic is that they do not emit light. However, their presence is clearly detected through their gravitational effects on nearby objects. In particular, gas accreting onto a black hole generates huge amounts of energy that create easily observable effects. In fact, accretion energy powers the most luminous objects in the Universe and can be much more efficient at turning mass into energy than the thermonuclear processes that power ordinary stars like the Sun. The fusion of hydrogen atoms to make more massive nuclei generates...

  6. 3 OUTFLOWS AND JETS
    (pp. 43-52)

    One somewhat unexpected feature of accretion flows is the presence of outflows, or jets. There is strong observational evidence that some fraction of the infalling material reverses course near the accreting object and is shot out perpendicularly to the accretion disk. In some cases out-flow velocities in the jet can be close to the speed of light, and the jets can carry energy over very large distances. In particular, narrow collimated beams of emission are observed emerging from the central-most regions of galaxies and continuing across the whole of the galaxy, depositing their energy hundreds of kiloparsecs away from their...

  7. 4 STELLAR-MASS BLACK HOLES
    (pp. 53-83)

    The empirical study of black holes began in the 1960s with the discovery of quasars (discussed in the next chapter) and the advent of X-ray astronomy. Since the atmosphere is opaque, celestial X-rays cannot be observed from the ground, so X-ray astronomy did not begin until the space age. Once observing X-rays became possible, it quickly became clear that the X-ray sky is dramatically different from the sky seen in optical light. Most of the optical light in the sky comes from stars, with nuclear fusion as the underlying power source. It is not surprising that this is the kind...

  8. 5 SUPERMASSIVE BLACK HOLES
    (pp. 84-105)

    Stellar-mass black holes are clearly common consequences of stellar evolution, but they are not the only kinds of black holes identified by astronomers. Much more massive black holes are located in the center of many, and perhaps all, galaxies, including our own. These black holes are referred to assupermassive black holes, sometimes abbreviated “ SMBHs.” They are responsible for a range of phenomena originating from objects described asactive galactic nuclei(abbreviated AGN), which were first observed in the form ofquasi-stellar objects(QSOs) orquasars.¹ AGN are among the most luminous objects in the Universe and can be...

  9. 6 FORMATION AND EVOLUTION OF BLACK HOLES
    (pp. 106-126)

    Most objects in the Universe are not black holes. One might wonder why not: any collection of matter with negative total energy (including the intrinsically negative gravitational potential energy) tends to collapse due to its self-gravity. This tendency, if unchecked, will pull all matter together until it falls within an event horizon. So why shouldn’t any gravitationally bound object quickly become a black hole? Alternatively, if the Universe is expanding faster than its own escape velocity, and the total energy of the Universe is positive, one might expect all matter to diverge into an increasingly sparse plasma and form no...

  10. 7 DO INTERMEDIATE-MASS BLACK HOLES EXIST?
    (pp. 127-134)

    There is powerful empirical evidence for two classes of black holes, namely, the stellar-mass black holes, with masses a few times that of the Sun, and the supermassive black holes at the centers of galaxies. The considerable gap in mass between these two categories naturally prompts the question whether black holes might exist at other mass scales. In recent years two lines of evidence have been presented in support of the idea that black holes with masses intermediate between stellar mass and supermassive might exist, that is, with masses of 10²–10⁵ Mo. Such sources are referred to asintermediate-mass...

  11. 8 BLACK HOLE SPIN
    (pp. 135-149)

    Black holes are among the simplest objects in the Universe. Simplicity and complexity can be defined by the number of parameters required to completely specify the properties of an object. This number is very large for such things as people, planets, stars, and galaxies—the chemical composition, pressure, and temperature all need to be defined at every point within the object. But a black hole can be completely defined by a mere three parameters: its overall mass, charge, and spin. The nature and distribution of material inside the event horizon has no impact on the observable properties of the black...

  12. 9 DETECTING BLACK HOLES THROUGH GRAVITATIONAL WAVES
    (pp. 150-166)

    The vast majority of our information concerning the cosmos arrives in the form of photons (electromagnetic radiation). Each photon can be characterized by four numbers, namely, the energy and arrival time of the photon, and two numbers characterizing its position on the sky.¹ So, our information about the Universe can be imagined as being contained in a very long table, each entry of which consists of four numbers, as well as the accuracy of each determination.

    Viewed in this light, the enormous progress in observational astrophysics over the past half-century can be viewed as advances in the range and resolution...

  13. 10 BLACK HOLE EXOTICA
    (pp. 167-178)

    Black holes are a staple of science fiction, where their effects are used as plot devices in a variety of ways. But the effects evoked by science fiction writers are generally not those observed by astronomers in the ways that are described in this book. Rather, they are extrapolations from the predicted behavior of black holes that have not yet been observed. But in principle these exotic behaviors are observable, and as science fiction correctly points out, they could have dramatic effects on people’s lives under the right circumstances. In this final chapter we explore some of these predicted effects...

  14. GLOSSARY
    (pp. 179-186)
  15. INDEX
    (pp. 187-210)