The scalar-tensor theory of gravitation is one of the most popular alternatives to Einstein's theory of gravitation. This book provides a clear and concise introduction to the theoretical ideas and developments, exploring scalar fields and placing them in context with a discussion of Brans-Dicke theory. Topics covered include the cosmological constant problem, time variability of coupling constants, higher dimensional space-time, branes and conformal transformations. The authors emphasize the physical applications of the scalar-tensor theory and thus provide a pedagogical overview of the subject, keeping more mathematically detailed sections for the appendices. This book is suitable for graduate courses in cosmology, gravitation and relativity. It will also provide a valuable reference for researchers.

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. It aims at detecting various kinds of gravitational waves between 1 mHz and 100 Hz frequently enough to open a new window of observation for gravitational wave astronomy. The pre-conceptual design of DECIGO consists of three drag-free satellites, 1000 km apart from each other, whose relative displacements are measured by a Fabry–Perot Michelson interferometer. We plan to launch DECIGO in 2024 after a long and intense development phase, including two pathfinder missions for verification of required technologies.

Using a black hole ͑BH͒ perturbation approach, we numerically study gravitational waves from a spinning particle of mass and spin s on the equatorial plane plunging into a Kerr BH of mass M and spin a. When we take into account the particle spin s, ͑a͒ the motion of the particle changes due to the coupling effects between s and the orbital angular momentum L z and between s and a, and also ͑b͒ the energy momentum tensor of the linearized Einstein equations changes. We calculate the total radiated energy, linear momentum, angular momentum, the energy spectrum, and waveform of gravitational waves, and we find the following features. ͑1͒ There are three spin coupling effects: between L z and a, between s and L z , and between s and a when s is considered. Among them, (L z •a) coupling is the most important effect for the amount of gravitational radiation, and the other two effects are not as remarkable as the first one. However, these effects are still important; for example, the total radiated energy changes by a factor of ϳ2 for the case of a/M ϭ0.6, L z /M ϭ1.5 if we change s from 0 to ՇM . ͑2͒ For the case when one of the three spins (a, L z , and s) is vanishing, the amount of gravitational radiation becomes larger ͑smaller͒ if spin axes of the other two are parallel ͑antiparallel͒. For the case when three spins are nonvanishing, the amount of gravitational radiation becomes maximum if all the axial directions of s, a, and L z coincide. Thus, our calculations indicate that in a coalescence of two black holes ͑BHs͒ whose spins and orbital angular momentum are aligned, gravitational waves are emitted most efficiently. ͓S0556-2821͑98͒05216-3͔

Extending the proof of the cosmic no-hair theorem for Bianchi models in power-law inflation, the authors prove a more general cosmic no-hair theorem for all 0

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Supernovae are explosions of stars which are triggered either by the implosion of the core of a star or a thermonuclear runaway, causing a bright optical display lasting for weeks to years. This chapter first explains the main explosion types, how they are classified and the principles that determine their lightcurves. It then discusses in more detail some of the most important supernova types, specifically SN 1987A, the last naked-eye supernova near our own Galaxy, Type Ia supernovae that have been used as standardizable cosmological distance candles, and gamma-ray bursts and their related supernovae. Special emphasis is given to the link of the various supernova types to their progenitor systems and a discussion of any outstanding issues. Causes for the large diversity of supernova types and sub-types are then systematically explored: these include binarity, the explosion mechanisms, rotation, metallicity and dynamical effects. Finally, some of the major topics of current interest are briefly discussed.1 Unlike supernovae that generally involve the whole star in the explosion, novae are now understood to be thermonuclear explosions in the envelopes of white dwarfs.

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