'Quasar Absorption Lines' is a comprehensive, detailed exposition on the science and analysis of quasar spectra in two volumes, for both aspiring and seasoned astronomers. This Volume 1: 'Introduction, Discoveries, and Methods' covers the evolution of the field of quasar spectroscopy over the six decades since quasars were discovered, including the development and application of observational methods and the knowledge gained from them. The broad treatment includes studies of the Ly α forest, Lyman limit systems, damped Ly α absorbers, deuterium (D/H), 21-cm absorbers, HI and HeII reionization, the warm/hot intergalactic medium, and the multiple ionization phases of metal lines. The connections between these absorbers and galaxies (the circumgalactic medium), galaxy groups (the intragroup medium), and clusters of galaxies (the intracluster medium) are treated in depth. Also covered are the taxonomy and classifications of AGN/quasar spectra, black hole accretion, broad and narrow associated absorption lines, and the quasar circumgalactic medium.

From the Foreword:‘The story of quasars and their absorption spectra accounts for just the first half of Professor Churchill's extraordinary two book set. [...] To collect all this encyclopedia of relevant knowledge [on quasars] under one assemblage has never been attempted before and is the phenomenal achievement of these two volumes. Students and experts in the field will find them an endless source of information and a much used reference text for many years to come.'

Max Pettini - University of Cambridge

‘Churchill has produced a masterful textbook that is both comprehensive and readable. From the field's historical foundations through to modern analysis methods and discoveries, this book is a deep dive into the field of quasar absorption lines. Combined with supporting material on topics from cosmology and simulations to instrumentation and the interstellar medium, Churchill's two-volume set is the ultimate reference for students and seasoned researchers alike.’

Sara Ellison - University of Victoria

‘This remarkable two-volume book set on quasar absorption lines is, all at once, a historical reference, a comprehensive review article, a presentation of a remarkable amount of relevant fundamental physics and cosmology, a tutorial on numerous facets of spectral analysis, a description of modeling methodology and of insights from cosmological simulations, and a presentation of current results on the nature of the variety of absorption line systems and their relationships to galaxies over most of cosmic history. Churchill covers all of this systematically, clearly, and in depth, with unique, profound insights interwoven throughout. Not only student researchers of all levels, but also seasoned veteran researchers, will find this reference to teach them something which could substantially increase their productivity in the field. There is nothing else like it.’

Jane Charlton - Penn State University

‘This outstanding two-volume set is long overdue for the Astrophysics community. Prof. Churchill captures the physics, science, and history of the rich field of quasar absorption lines. It can serve as the primary textbook for any class on the intergalactic medium or provide the foundational reference for research on the topic.’

J. Xavier Prochaska - UC Santa Cruz