Jelle Kaastra – författare

The existence of soft excess emission originating from clusters of galaxies, de ned as em- sion detected below 1 keV in excess over the usual thermal emission from hot intracluster gas (hereafter the ICM) has been claimed since 1996. Soft excesses are particularly - portant to detect because they may (at least partly) be due to thermal emission from the Warm-Hot Intergalactic Medium, where as much as half of the baryons of the Universe could be. They are therefore of fundamental cosmological importance. Soft excess emission has been observed (and has also given rise to controversy) in a number of clusters, mainly raising the following questions: (1) Do clusters really show a soft excess? (2) If so, from what spatial region(s) of the cluster does the soft excess or- inate? (3) Is this excess emission thermal, originating from warm-hot intergalactic gas (at 6 temperatures of?10 K), or non-thermal, in which case several emission mechanisms have been proposed. Interestingly, some of the non-thermal mechanisms suggested to account for soft excess emission can also explain the hard X-ray emission detected in some clusters, for example by RXTE and BeppoSAX (also see Petrosian et al. 2008—Chap. 10, this issue; Rephaeli et al. 2008—Chap. 5, this issue).

The existence of soft excess emission originating from clusters of galaxies, de ned as em- sion detected below 1 keV in excess over the usual thermal emission from hot intracluster gas (hereafter the ICM) has been claimed since 1996. Soft excesses are particularly - portant to detect because they may (at least partly) be due to thermal emission from the Warm-Hot Intergalactic Medium, where as much as half of the baryons of the Universe could be. They are therefore of fundamental cosmological importance. Soft excess emission has been observed (and has also given rise to controversy) in a number of clusters, mainly raising the following questions: (1) Do clusters really show a soft excess? (2) If so, from what spatial region(s) of the cluster does the soft excess or- inate? (3) Is this excess emission thermal, originating from warm-hot intergalactic gas (at 6 temperatures of?10 K), or non-thermal, in which case several emission mechanisms have been proposed. Interestingly, some of the non-thermal mechanisms suggested to account for soft excess emission can also explain the hard X-ray emission detected in some clusters, for example by RXTE and BeppoSAX (also see Petrosian et al. 2008—Chap. 10, this issue; Rephaeli et al. 2008—Chap. 5, this issue).

The existence of soft excess emission originating from clusters of galaxies, de ned as em- sion detected below 1 keV in excess over the usual thermal emission from hot intracluster gas (hereafter the ICM) has been claimed since 1996. Soft excesses are particularly - portant to detect because they may (at least partly) be due to thermal emission from the Warm-Hot Intergalactic Medium, where as much as half of the baryons of the Universe could be. They are therefore of fundamental cosmological importance. Soft excess emission has been observed (and has also given rise to controversy) in a number of clusters, mainly raising the following questions: (1) Do clusters really show a soft excess? (2) If so, from what spatial region(s) of the cluster does the soft excess or- inate? (3) Is this excess emission thermal, originating from warm-hot intergalactic gas (at 6 temperatures of?10 K), or non-thermal, in which case several emission mechanisms have been proposed. Interestingly, some of the non-thermal mechanisms suggested to account for soft excess emission can also explain the hard X-ray emission detected in some clusters, for example by RXTE and BeppoSAX (also see Petrosian et al. 2008—Chap. 10, this issue; Rephaeli et al. 2008—Chap. 5, this issue).

High-resolution X-ray spectroscopy has become a powerful tool for astrophysics since the launch of Chandra and XMM-Newton, ten years ago. The grating spectrometers on both instruments still continue to provide excellent data, while imaging calorimeters are being prepared for future missions like Astro-H and IXO. The synergy with other wavelength bands like the UV has been boosted by the addition of COS to HST. X-ray spectroscopy offers unique diagnostics to study almost any object in the Universe. This book contains review papers on highlights and the state-of-the-art of X-ray spectroscopy for a broad range of objects and on the prospects for future studies.

High-resolution X-ray spectroscopy has become a powerful tool for astrophysics since the launch of Chandra and XMM-Newton, ten years ago. The grating spectrometers on both instruments still continue to provide excellent data, while imaging calorimeters are being prepared for future missions like Astro-H and IXO. The synergy with other wavelength bands like the UV has been boosted by the addition of COS to HST. X-ray spectroscopy offers unique diagnostics to study almost any object in the Universe. This book contains review papers on highlights and the state-of-the-art of X-ray spectroscopy for a broad range of objects and on the prospects for future studies.

Thisbook offers eleven coordinated reviews on multi-scalestructure formation in cosmic plasmas in the Universe. Observations and theories of plasma structures are presentedin all relevant astrophysical contexts, from the Earth’s magnetosphere  through heliospheric and galactic scales to  clusters of galaxies and the large scalestructure of the Universe. Basic processes in cosmic plasmas starting fromelectric currents and the helicity concept governing the dynamics of magnetic structures in planet magnetospheres,stellar winds, and relativistic plasma outflows like pulsar wind nebulae andActive Galactic Nuclei jets are covered. Themulti-wavelength view from the radio to gamma-rays with modern high resolutiontelescopes discussed in the book reveals a beautiful and highly informativepicture of both coherent and chaotic plasma structures tightly connected bystrong mutual influence. The authors are all leading scientists in theirfields, making this book an authoritative, up‐to‐date and enduring contributionto astrophysics.

Thisbook offers eleven coordinated reviews on multi-scalestructure formation in cosmic plasmas in the Universe. Observations and theories of plasma structures are presentedin all relevant astrophysical contexts, from the Earth’s magnetosphere  through heliospheric and galactic scales to  clusters of galaxies and the large scalestructure of the Universe. Basic processes in cosmic plasmas starting fromelectric currents and the helicity concept governing the dynamics of magnetic structures in planet magnetospheres,stellar winds, and relativistic plasma outflows like pulsar wind nebulae andActive Galactic Nuclei jets are covered. Themulti-wavelength view from the radio to gamma-rays with modern high resolutiontelescopes discussed in the book reveals a beautiful and highly informativepicture of both coherent and chaotic plasma structures tightly connected bystrong mutual influence. The authors are all leading scientists in theirfields, making this book an authoritative, up‐to‐date and enduring contributionto astrophysics.

Clusters of galaxies are large assemblies of galaxies, hot gas and dark matter bound together by gravity. Galaxy clusters are now one of the most important cosmological probes to test the standard cosmological models. Constraints on the Dark Energy equation of state from the cluster number density measurements, deviations from the Gaussian perturbation models, the Sunyaev-Zeldovich effect as well as the dark matter proles are among the issues to be studied with clusters. The baryonic composition of clusters is dominated by hot gas that is in quasi-hydrostatic equilibrium within the dark matter-dominated gravitational potential well of the cluster. The hot gas is visible through spatially extended thermal X-ray emission, and it has been studied extensively both for assessing its physical properties and as a tracer of the large-scale structure of the Universe. Magnetic fields as well as a number of non-thermal plasma processes play a role in clusters of galaxies as we observe from radioastronomical observations.The goal of this volume is to review these processes and to investigate how they are interlinked. Overall, these papers provide a timely and comprehensive review of the multi-wavelength observations and theoretical understanding of clusters of galaxies in the cosmological context. Thus, the volume will be particularly useful to postgraduate students and researchers active in various areas of astrophysics and space science. Originally published in Space Science Reviews in the Topical Collection "Clusters of Galaxies: Physics and Cosmology"