5 Thermonuclear X-ray Bursts
251
However, an explanation for these events in terms of nuclear physics must also
necessarily explain why the double-peaked behaviour is not observed in every burst.
More systematic investigations using a combination of single- and multi-zone
models attempted to identify all of the most significant reactions that might be
expected to affect the burst lightcurves [33]. These investigations were integrated
into the ongoing REACLIB 7 project, which seeks to collect, curate, and distribute
data on nuclear reaction rates and masses to broadly impact the astrophysical
modelling community. The most recent results from this project have provided
a clear list of priority reactions for investigation via nuclear experiment [34].
However, it is worth noting that the sensitivity studies are based on a single burst
model, and it is possible that different reactions may have significant impacts on the
lightcurves of bursts in different regimes (see Sect. 5.1.1.4).
A detailed description of the nuclear experiments focussed on reactions or masses
of relevance for thermonuclear bursts is beyond the scope of this review (see
instead [147]). However, we comment that in the past few years an increasing
level of interaction has taken place between the experimental community, and
burst observers and modellers, enabled in a large part by the activities of the Joint
Institute for Nuclear Astrophysics: Centre for the Evolution of the Elements (JINACEE 8 ). This growing dialogue, in combination with new experimental techniques,
and upcoming hardware including the Facility for Rare Isotope Beams (from 2021
onwards), suggest that the most exciting time for studying the nuclear reactions in
bursts is yet to come.
5.10 Summary and Outlook
In the last decade, studies of thermonuclear bursts have entered an exciting new
phase, where the interplay of observations, numerical modelling, and nuclear experiments are making substantial progress on understanding the burst phenomenology.
At the same time, the interpretation of observational data (motivated in part by
constraining the mass and radius; see Miller chapter, this volume) has driven new
investigations into the spectral formation processes.
The diversity of burst behaviour, although still not completely understood,
presents a continuing challenge to these investigations. The computational challenges in simulating the entire neutron star surface remain, but even 1-D models
are achieving success in reproducing an increasing range of observed phenomena.
Assembly and analysis of large databases of observations and simulations appear
to offer the best chance for understanding all the possible ignition cases. More
comprehensive sensitivity studies have the prospects of conclusively identifying
the nuclear reactions most important to the full range of burst types, and hence
7 https://groups.nscl.msu.edu/jina/reaclib/db.
8 http://jinaweb.org.
251
However, an explanation for these events in terms of nuclear physics must also
necessarily explain why the double-peaked behaviour is not observed in every burst.
More systematic investigations using a combination of single- and multi-zone
models attempted to identify all of the most significant reactions that might be
expected to affect the burst lightcurves [33]. These investigations were integrated
into the ongoing REACLIB 7 project, which seeks to collect, curate, and distribute
data on nuclear reaction rates and masses to broadly impact the astrophysical
modelling community. The most recent results from this project have provided
a clear list of priority reactions for investigation via nuclear experiment [34].
However, it is worth noting that the sensitivity studies are based on a single burst
model, and it is possible that different reactions may have significant impacts on the
lightcurves of bursts in different regimes (see Sect. 5.1.1.4).
A detailed description of the nuclear experiments focussed on reactions or masses
of relevance for thermonuclear bursts is beyond the scope of this review (see
instead [147]). However, we comment that in the past few years an increasing
level of interaction has taken place between the experimental community, and
burst observers and modellers, enabled in a large part by the activities of the Joint
Institute for Nuclear Astrophysics: Centre for the Evolution of the Elements (JINACEE 8 ). This growing dialogue, in combination with new experimental techniques,
and upcoming hardware including the Facility for Rare Isotope Beams (from 2021
onwards), suggest that the most exciting time for studying the nuclear reactions in
bursts is yet to come.
5.10 Summary and Outlook
In the last decade, studies of thermonuclear bursts have entered an exciting new
phase, where the interplay of observations, numerical modelling, and nuclear experiments are making substantial progress on understanding the burst phenomenology.
At the same time, the interpretation of observational data (motivated in part by
constraining the mass and radius; see Miller chapter, this volume) has driven new
investigations into the spectral formation processes.
The diversity of burst behaviour, although still not completely understood,
presents a continuing challenge to these investigations. The computational challenges in simulating the entire neutron star surface remain, but even 1-D models
are achieving success in reproducing an increasing range of observed phenomena.
Assembly and analysis of large databases of observations and simulations appear
to offer the best chance for understanding all the possible ignition cases. More
comprehensive sensitivity studies have the prospects of conclusively identifying
the nuclear reactions most important to the full range of burst types, and hence
7 https://groups.nscl.msu.edu/jina/reaclib/db.
8 http://jinaweb.org.