Journal of Dentistry Defence Section

Dijkstra M.

In the original version of this book, the following belated correction has been incorporated: In Chapter 1, Figure 1.35 has been replaced with the revised figure. The erratum chapter and the book have been updated with the change.

Dijkstra M.

The Ly$$\alpha $$ transfer problem is an exciting problem to learn about and work on. Ly$$\alpha $$ transfer is deeply rooted in quantum physics, it requires knowledge of statistics, statistical physics/thermodynamics, computational astrophysics, and has applications in a wide range of astrophysical contexts including galaxies, the interstellar medium, the circum-galactic medium, the intergalactic medium, reionization, 21-cm cosmology and astrophysics. In these lectures I will describe the basics of Ly$$\alpha $$ radiative processes and transfer. These lectures are aimed to be self-contained, and are (hopefully) suitable for anyone with an undergraduate degree in astronomy/physics. Throughout these notes, I denote symbols that represent vectors in bold print. Throughout I will use CGS units, as is common in the literature. Table 1.1 provides an overview of (some of the) symbols that appear throughout these notes.

Prochaska J.X.

We review studies of the intergalactic medium (IGM) via HI absorption with emphasis on the decades of previous research with quasar absorption line studies. The chapter begins with a historical perspective and then offers a pedagogical description of the quantum mechanics underlying the Lyman series and Lyman continuum opacity of the HI atom. We describe the manifestation of these opacities in absorption spectroscopy and the challenges related to normalization of quasar emission. Standard measurement techniques (equivalent width, line-profile fitting) are introduced. We then introduce the $$N_\mathrm{HI}$$ frequency distribution $$f(N_\mathrm{HI})$$ and efforts to constrain this distribution across cosmic time with emphasis on the optically thin Ly$$\alpha $$ forest. A discussion of optically thick gas (Lyman limit systems and damped Ly$$\alpha $$ systems) and its relation to the mean free path is presented. Online presentations and Python notebooks supplement this chapter with examples, a review of modern work, and thoughts on future progress. See https://github.com/profxj/SaasFee2016 for additional resources.

Hayes M.

Lecture notes concerning observations of the Lyman alpha (Ly$$\alpha $$) transition of atomic hydrogen in low-redshift (z) galaxies. Section 1 discusses the main motivations, astrophysical prerequisites, and definitions. Section 2 describes the various instruments that have contributed to the field or are currently capable of observing Ly$$\alpha $$ at $$z

Ouchi M.

InLy Emitter (LAE) this series of lectures, I review our observational understanding of high-z Ly$$\alpha $$ emitters (LAEs) and relevant scientific topics. Since the discovery of LAEs in the late 1990s, significant progresses in LAE studies have been made over the past two decades by deep multi-wavelength observations. More than ten thousands of LAEs have been identified photometrically, and more than one thousand spectroscopically, in optical and near-infrared data, and the redshifts of these LAEs range from $$z\sim 0$$ to $$z\sim 10$$. These large samples of LAEs are useful to address two major astrophysical issues, galaxy formation and cosmic reionization. Statistical studies have revealed the general picture of LAEs’ physical properties: young stellar populations, remarkable luminosity function evolutions, compact morphologies, highly ionized inter-stellar media (ISM) with low metal/dust contents, low masses of dark-matter halos. Typical LAEs represent low-mass high-z galaxies, high-z analogs of dwarf galaxies, some of which are thought to be candidates of population III galaxies. These observational studies have also pinpointed rare bright Ly$$\alpha $$ sources extended over $${\sim }10$$–100 kpc, dubbed Ly$$\alpha $$ blobs, whose physical origins are under debate. LAEs are used as probes of cosmic reionization history through the Ly$$\alpha $$ damping wing absorption given by the neutral hydrogen of the inter-galactic medium (IGM), which complement the cosmic microwave background radiation and 21 cm observations targeting the epoch of reionization. The low-mass and highly-ionized population of LAEs can be major sources of cosmic reionization, and physical parameters including the ionizing photon escape fraction have been extensively investigated. The budget of ionizing photons for cosmic reionization has been constrained, although there remain large observational uncertainties in the parameters. Beyond these two established topics of LAEs, galaxy formation and cosmic reionization, several new usages of LAEs for science frontiers have been suggested such as the distribution of Hi gas in the circum-galactic medium and filaments of large-scale structures. On-going 10 m-class optical telescope programs and future telescope projects, such as JWST, ELTs, and SKA, will address the remaining open questions related to LAEs, and push the horizons of the science frontiers.

Cornish N.J.

I was tasked with covering a wide swath of gravitational wave astronomy—including theory, observation, and data analysis—and to describe the detection techniques used to span the gravitational wave spectrum—pulsar timing, ground based interferometers and their future space based counterparts. For good measure, I was also asked to include an introduction to general relativity and black holes. Distilling all this material into nine lectures was quite a challenge. The end result is a highly condensed set of lecture notes that can be consumed in a few hours, but may take weeks to digest.

King A.

I review the physics of accretion on to supermassive black holes in galaxy centres, and how this results in feedback affecting the host galaxy.

Di Matteo T.

Massive black holes are fundamental constituents of our cosmos, from the Big Bang to today. Understanding their formation at cosmic dawn, their growth, and the emergence of the first, rare quasars in the early Universe remains one of our greatest theoretical and observational challenges. Hydrodynamic cosmological simulations self-consistently combine the processes of structure formation at cosmological scales with the physics of smaller, galaxy scales. They capture our most realistic understanding of massive black holes and their connection to galaxy formation and have become the primary avenue for theoretical research in this field. The space-based gravitational wave telescope LISA will open up new investigations into the dynamical processes involving massive black holes. Multi-messenger astrophysics brings new exciting prospects for tracing the origin, growth and merger history of massive black holes across cosmic ages.

Armitage P.J.

This review, based on lectures given at the 45th Saas-Fee Advanced Course “From Protoplanetary Disks to Planet Formation”, introduces physical processes in protoplanetary disks relevant to accretion and the initial stages of planet formation. After a brief overview of the observational context, I introduce the elementary theory of disk structure and evolution, review the gas-phase physics of angular momentum transport through turbulence and disk winds, and discuss possible origins for the episodic accretion observed in Young Stellar Objects. Turning to solids, I review the evolution of single particles under aerodynamic forces, and describe the conditions necessary for the development of collective gas-particle instabilities. Observations show that disks can exhibit pronounced large-scale structure, and I discuss the types of structures that may form from gas and particle interactions at ice lines, vortices and zonal flows, prior to the formation of large planetary bodies. I conclude with disk dispersal.

Kley W.

This review is based on lectures given at the 45th Saas-Fee Advanced Course “From Protoplanetary Disks to Planet Formation” held in March 2015 in Les Diablerets, Switzerland. Starting with an overview of the main characterictics of the Solar System and the extrasolar planets, we describe the planet formation process in terms of the sequential accretion scenario. First the growth processes of dust particles to planetesimals and subsequently to terrestrial planets or planetary cores are presented. This is followed by the formation process of the giant planets either by core accretion or gravitational instability. Finally, the dynamical evolution of the orbital elements as driven by disk-planet interaction and the overall evolution of multi-object systems is presented.

Wilson T.L.

This chapter provides an introduction to the basics of radiative transfer, receivers, antennas and interferometry. Following this is an exposition of radiation mechanisms for continuum, atoms and molecules. Much of this material is contained in Rohlfs and Wilson (Tools of Radio Astronomy, Springer, Berlin, 2004, [36]), Wilson et al. (Tools of Radio Astronomy, Springer, Berlin, 2013, [52]). This chapter places more emphasis on current research in millimeter/sub-millimeter astronomy. The field of mm/sub-mm astronomy has become very large, so this presentation contains only a few derivations. In some cases, the approach is to quote a result followed by an example. Some common terms are used, but “jargon” has been avoided as much as possible. For the most part, references are to more recent work, where citations to earlier publications can be found. The units are mostly CGS with some SI units. This follows the usage in the astronomy literature. One topic not covered here is the polarization (see Rohlfs and Wilson, Tools of radio astronomy. Springer, Berlin, 2004, [36], Thum et al., [47] for an introduction). Another glaring omission is a treatment of the Cosmic Microwave Background (CMB), since this is not treated in the following lecture. The CMB emission is not weak, but does fill the entire sky, so special techniques and different interpretations must be employed.

Guilloteau S.

Stars are believed to form from interstellar material through the gravitational collapse of dusty clouds. Interstellar medium is a very dynamical environment in which clouds of atomic gas (and its associated dust counterpart) form in warm medium fragments, perhaps as a result of turbulence or the passage of shock, and subsequently cool down and condense. Although the dust is a tiny fraction (of order 1%) of the total material mass, it plays a major role in the cloud evolution because its opacity can shield the cloud center from the interstellar UV field and dust surfaces act as a catalyst on which molecular hydrogen can form. For high enough column density, the combined effect of dust shielding and self-shielding of H $$_2$$ turn the initially predominantly atomic gas into molecular form. H $$_2$$ forms first, but more and more complex species such as CO, CN, and HCN, form during cloud evolution.

Mathieu R.D.

In the previous chapters we have discussed the products of the star formation process. In the remaining chapters we focus on an overview of star-forming regions; however, in this chapter we take an in-depth look at one young region in particular, the $$\lambda $$ Orionis association. Our discussion begins by placing the $$\lambda $$ Ori region in context through investigating the local environment, namely the interstellar dust and molecular gas. We then move on to a census of the stellar population of the $$\lambda $$ Ori region, briefly introducing the high-mass stars, before providing a more comprehensive description of the low-mass stars, specifically in terms of the history of their identification and what information we can extract from them concerning the star formation history of the region. We conclude by using this analysis to create an almost complete picture of how the region formed and subsequently evolved to its current state of dissolving into the Galactic field.

Clarke C.J.

Stars form out of the collapse of cold, dark regions in GMCs within which the gravitational force can overcome the supportive effects provided by thermal pressure, magnetic fields and turbulent forces (so-called ‘supercritical regions’). The subsequent evolution of the dense self-gravitating gas from protostars to pre-main-sequence stars is driven by a combination of interactions between the star-disc system as well as dynamical evolution within the star cluster itself. This chapter introduces the reader to the main numerical techniques adopted in the study of star cluster simulations, primarily N-body, as well as grid-based and Lagrangian hydrodynamical codes. We begin by discussing the overly simplistic purely gravitational collapse scenario, before moving onto the inclusion of ‘additional physics’ such as magnetic fields as well as thermal and mechanical feedback in such codes.

Reid I.N.

Stars form within clusters and associations, which gradually dissipate through gravitational interactions, dispersing the component stars throughout the Milky Way. The prime aim of stellar kinematics is to describe the current motions of stars and use those statistical quantities to probe their dynamical history. This chapter describes its origins in Jacobus Kapteyn’s systematic analyses of photographic plates taken at the Cape Observatory run by David Gill and provides a summary of our current knowledge of the kinematics of local stars, notably results generated by the Hipparcos astrometric mission. We discuss the evidence for ‘star streams’ and whether these kinematic groupings reflect residual components of individual stellar clusters, or whether they are generated by dynamical resonances generated by large-scale features such as the Bar. We consider the potential for stellar migration and radial mixing within the Milky Ways disc.