14 research outputs found
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Shock wave physics and detonation physics â a stimulus for the emergence of numerous new branches in science and engineering
In the period of the Cold War (1945â1991), Shock Wave Physics and Detonation Physics
(SWP&DP) â until the beginning of WWII mostly confined to gas dynamics, high-speed
aerodynamics, and military technology (such as aero- and terminal ballistics, armor
construction, chemical explosions, supersonic gun, and other firearms developments) â
quickly developed into a large interdisciplinary field by its own. This rapid expansion
was driven by an enormous financial support and two efficient feedbacks: the
Terminal Ballistic Cycle and the Research &
Development Cycle. Basic knowledge in SWP&DP, initially gained
in the Classic Period (from 1808) and further extended in the
Post-Classic Period (from the 1930s to present), is now increasingly
used also in other branches of Science and Engineering (S&E). However, also
independent S&E branches developed, based upon the fundamentals of SWP&DP,
many of those developments will be addressed (see Tab. 2). Thus, shock wave and detonation
phenomena are now studied within an enormous range of dimensions, covering microscopic,
macroscopic, and cosmic dimensions as well as enormous time spans ranging from
nano-/picosecond shock durations (such as produced by ultra-short laser pulses) to shock
durations that continue for centuries (such as blast waves emitted from ancient supernova
explosions). This paper reviews these developments from a historical perspective