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Gamma-Ray Bursts as Probes of the Universe

Joshua S. Bloom

in What Are Gamma-Ray Bursts?

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact ... More

This chapter focuses on how gamma-ray bursts (GRBs) are emerging as unique tools in the study of broad areas of astronomy and physics by virtue of their special properties. The unassailable fact about GRBs that makes them such great probes is that they are fantastically bright and so can be seen to the farthest reaches of the observable Universe. In parallel with the ongoing study of GRB events and progenitors, new lines of inquiry have burgeoned: using GRBs as unique probes of the Universe in ways that are almost completely divorced from the nature of GRBs themselves. Topics discussed include studies of gas, dust, and galaxies; the history of star formation; measuring reionization and the first objects in the universe; neutrinos, gravitational waves, and cosmic rays; quantum gravity and the expansion of the universe; and the future of GRBs.Less

Stellar Feedback and Galaxy Formation

Abraham Loeb and Steven R. Furlanetto

in The First Galaxies in the Universe

This chapter studies radiative, mechanical, and chemical feedback in the earliest gaseous clouds, taking up the thread of discussion in the previous chapter to consider the influences placed on the ... More

This chapter studies radiative, mechanical, and chemical feedback in the earliest gaseous clouds, taking up the thread of discussion in the previous chapter to consider the influences placed on the formation of second-generation stars. While the feedback effects are sufficiently complex that a complete description of them is well beyond the capabilities of present-day computer simulations, the general principles that underlie them are well known. Therefore, the chapter focuses on these principles and then briefly sketches the global picture. Feedback is important in all galaxies, and many of the principles that are discussed in this chapter apply on a much wider scale than just the first stars and galaxies.Less

Pre-main-sequence stars

Leon Mestel

in Stellar Magnetism: Second Edition

This chapter discusses the following: the later stages of star formation; magnetic accretion discs; pre-main-sequence rotational evolution; x-ray observations; accretion disc theory; models with ... More

This chapter discusses the following: the later stages of star formation; magnetic accretion discs; pre-main-sequence rotational evolution; x-ray observations; accretion disc theory; models with reduced magnetic coupling between star and disc; disc locking; instability in a magnetic rotating disc; disc dynamos; centrifugal winds from discs; and collimation.Less

The First Stars

Abraham Loeb and Steven R. Furlanetto

in The First Galaxies in the Universe

This chapter considers the emergence of the complex chemical and radiative processes during the first stages of galaxy formation. It studies the appearance of the first stars, their feedback ... More

This chapter considers the emergence of the complex chemical and radiative processes during the first stages of galaxy formation. It studies the appearance of the first stars, their feedback processes, and the resulting ionization structures that emerged during and shortly after the cosmic dawn. The formation of the first stars tens or hundreds of millions of years after the Big Bang had marked a crucial transition in the early Universe. Before this point, the Universe was elegantly described by a small number of parameters. But as soon as the first stars formed, more complex processes entered the scene. To illustrate this, the chapter provides a brief outline of the prevailing (though observationally untested) theory for this cosmological phase transition.Less

Magnetism and star formation II

Leon Mestel

in Stellar Magnetism: Second Edition

This chapter discusses the following: magneto-gravitational equilibrium and exact disc-like models; magneto-turbulent cloud models; evolution through flux diffusion; gravitational collapse; field ... More

This chapter discusses the following: magneto-gravitational equilibrium and exact disc-like models; magneto-turbulent cloud models; evolution through flux diffusion; gravitational collapse; field line detachment; flux leakage; magnetic ‘levitation’; Alfvénic turbulence; turbulent ambipolar diffusion, and magneto-turbulence and star formation.Less

Galaxy formation

J. Silk, A. DiCintio, and I. Dvorkin

in Post-Planck Cosmology: Lecture Notes of the Les Houches Summer School: Volume 100, July 2013

In this chapter, galaxy formation theory is reviewed and confronted with recent observational issues. Galaxy formation is at the forefront of observation and theory in cosmology. An improved ... More

In this chapter, galaxy formation theory is reviewed and confronted with recent observational issues. Galaxy formation is at the forefront of observation and theory in cosmology. An improved understanding is essential for improving knowledge of cosmological parameters, the contents of the universe, and its origins. In the first part of the chapter, the following topics are presented: star formation considerations, including the initial mass function (IMF), star formation efficiency, and star formation rate; the origin of the galaxy luminosity function; and feedback in dwarf galaxies. The second part of the chapter describes the formation of disks and massive spheroids, including the growth of supermassive black holes; negative feedback in spheroids; the active galactic nucleus (AGN)–star formation connection; star formation rates at high redshift; and the baryon fraction in galaxies.Less

Other Probes of the First Galaxies

Abraham Loeb and Steven R. Furlanetto

in The First Galaxies in the Universe

This chapter discusses several other ways to probe structures during the cosmic dawn. It first turns to secondary anisotropies of the cosmic microwave background, which are generated as the photons ... More

This chapter discusses several other ways to probe structures during the cosmic dawn. It first turns to secondary anisotropies of the cosmic microwave background, which are generated as the photons passed through gas during the cosmic dawn. Next, the chapter turns to diffuse backgrounds from the cosmic dawn, which typically include galactic emission lines, ranging from CO lines in the radio to the Lyman-α‎ line itself. Finally, the chapter observes that fossil structure from early galaxies remains in (or can be deduced from) the Milky Way or other nearby entities in the Local Group. This fossil structure includes the residual effects of feedback on the small satellite galaxies or globular clusters of the Milky Way, old low-mass stars that may have formed during the cosmic dawn and survive inside the Milky Way (or its halo), and remnant signatures of the early merger history of the Milky Way.Less

The Birth of Stars and Planets

Karel Schrijver

in One of Ten Billion Earths: How we Learn about our Planet's Past and Future from Distant Exoplanets

Exoplanets were discovered only a century after the true nature of stars was revealed, and yet—as explained in this chapter—their existences are inseparably linked. The birth of stars in densely ... More

Exoplanets were discovered only a century after the true nature of stars was revealed, and yet—as explained in this chapter—their existences are inseparably linked. The birth of stars in densely packed nurseries obscured by gas and dust initially hid how planetary systems formed around these stars. With powerful new telescopes, capable of looking from the infrared to X-rays, a complete picture has emerged. But first, astronomers had to work out the properties of the stars themselves so that eventually their planetary systems could be understood: planets can change orbits, toss asteroids about to fracture budding planets or strip them of their atmospheres, and can deliver precious water. Giant planets need the icy cold of distant space far from their stars in order to take shape fast enough to capture large amounts of gas, so how can it be that many are found close to their stars?Less

Building a Home

Karel Schrijiver and Iris Schrijiver

in Living with the Stars: How the Human Body is Connected to the Life Cycles of the Earth, the Planets, and the Stars

This chapter explores what it takes to make a habitable planet, as well as the discovery of planets outside our own solar system (exoplanets). Many stars in the night sky have one or more planets: ... More

This chapter explores what it takes to make a habitable planet, as well as the discovery of planets outside our own solar system (exoplanets). Many stars in the night sky have one or more planets: there may be several hundred billion planets within our galaxy alone. Computer experiments are beginning to reveal that planets are a natural consequence of the formation of the stars around which they orbit, and we are learning about their processes of formation and evolution. In our galaxy alone about a billion planets may have surface water and be habitable. Life, however, has only one confirmed home in the universe: the Earth. There are many small bodies, called asteroids, between the orbits of Mars and Jupiter. Those pulled from their orbits occasionally hit the Earth, and our bodies contain traces of them.Less

Priscilla Fairfield Bok (1896–1975)

Daniel R. Altschuler and Fernando J. Ballesteros

in The Women of the Moon: Tales of Science, Love, Sorrow, and Courage

This chapter focuses on the work and life of the marriage formed by Priscilla Fairfield Bok and her husband, Bart Bok, both astronomers.