47 research outputs found
Models for Type Ia supernovae and related astrophysical transients
We give an overview of recent efforts to model Type Ia supernovae and related
astrophysical transients resulting from thermonuclear explosions in white
dwarfs. In particular we point out the challenges resulting from the
multi-physics multi-scale nature of the problem and discuss possible numerical
approaches to meet them in hydrodynamical explosion simulations and radiative
transfer modeling. We give examples of how these methods are applied to several
explosion scenarios that have been proposed to explain distinct subsets or, in
some cases, the majority of the observed events. In case we comment on some of
the successes and shortcoming of these scenarios and highlight important
outstanding issues.Comment: 20 pages, 2 figures, review published in Space Science Reviews as
part of the topical collection on supernovae, replacement corrects typos in
the conclusions sectio
First direct measurement of 12C (12C,n) 23Mg at stellar energies
© 2016 Owned by the authors, published by EDP Sciences. Neutrons produced by the carbon fusion reaction12C(12C,n)23Mg play an important role in stellar nucleosynthesis. Past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement which extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction12C(12C,p)23Na. The new reaction rate has been determined with a well-defined uncertainty which exceeds the precision required by astrophysics models. Using our constrained rate, we find that12C(12C,n)23Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae
Classification of Supernovae
The current classification scheme for supernovae is presented. The main
observational features of the supernova types are described and the physical
implications briefly addressed. Differences between the homogeneous
thermonuclear type Ia and similarities among the heterogeneous core collapse
type Ib, Ic and II are highlighted. Transforming type IIb, narrow line type
IIn, supernovae associated with GRBs and few peculiar objects are also
discussed.Comment: 16 Pages, 4 figures, to be published in "Supernovae and Gamma-Ray
Bursters," ed. Kurt W. Weile
Astronomical Distance Determination in the Space Age: Secondary Distance Indicators
The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)
Dust in Supernovae and Supernova Remnants I : Formation Scenarios
Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe
Observations of metals in the intra-cluster medium
Because of their deep gravitational potential wells, clusters of galaxies
retain all the metals produced by the stellar populations of the member
galaxies. Most of these metals reside in the hot plasma which dominates the
baryon content of clusters. This makes them excellent laboratories for the
study of the nucleosynthesis and chemical enrichment history of the Universe.
Here we review the history, current possibilities and limitations of the
abundance studies, and the present observational status of X-ray measurements
of the chemical composition of the intra-cluster medium. We summarise the
latest progress in using the abundance patterns in clusters to put constraints
on theoretical models of supernovae and we show how cluster abundances provide
new insights into the star-formation history of the Universe.Comment: 28 pages, 12 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 16; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Catching Element Formation In The Act ; The Case for a New MeV Gamma-Ray Mission: Radionuclide Astronomy in the 2020s
High Energy Astrophysic