Neutron star mergers as the astrophysical site of the r-process in the Milky Way and its satellite galaxies
Neutron star mergers as the astrophysical site of the r-process in the Milky Way and its satellite galaxies
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中子星合并作为银河系及其卫星星系中 r 过程的天体物理场所
DOI：
10.1093/mnras/stab1655
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发表时间：
2021
影响因子：
4.8
通讯作者：
Prantzos Nikos
中科院分区：
文献类型：
--
作者：
Wanajo Shinya;Hirai Yutaka;Prantzos Nikos
核合成工作的最新进展以及与引力波源GW170817相关的千新星的发现表明，中子星合并（NSM）可能是r过程的一个场所。然而，几项关于银河系化学演化的研究指出了这一观点与观测到的银河系恒星丰度特征之间的不一致：(a)低金属丰度（光晕）处存在Eu， (b)高金属丰度（盘）处Eu/Fe呈下降趋势。在这项研究中，我们探索了银河系的晕、盘和卫星矮星系的星系化学演化。特别注意Ia型超新星（SN Ia）和nsm的延迟时间分布形式。银河系晕被建模为具有不同质量的独立演化的积木星系的集合。单一的构造块以及盘状矮星和卫星矮星被视为混合良好的单区系统。我们的研究结果表明，上述不一致是可以解决的，因此nsm可以成为银河系中唯一的r-过程位点，前提是延迟时间分布满足以下条件：(i)第一个SN Ia出现的长延迟（~ 1 Gyr）（或其数量的缓慢早期增加）和（ii）所有nsm的额外早期分量提供延迟~ 0.1 Gyr。在我们的模型中，光晕中r-过程增强的恒星和r-过程缺乏的恒星似乎分别起源于超微小的矮星大小和巨大的构建块。我们的结果还表明，双中子星的出生踢对盘内Eu的演化影响很小。
Recent progress of nucleosynthesis work as well as the discovery of a kilonova associated with the gravitational-wave source GW170817 indicates that neutron star mergers (NSM) can be a site of the r-process. Several studies of galactic chemical evolution, however, have pointed out inconsistencies between this idea and the observed stellar abundance signatures in the Milky Way: (a) the presence of Eu at low (halo) metallicity and (b) the descending trend of Eu/Fe at high (disc) metallicity. In this study, we explore the galactic chemical evolution of the Milky Way’s halo, disc, and satellite dwarf galaxies. Particular attention is payed to the forms of delay-time distributions for both type Ia supernovae (SN Ia) and NSMs. The Galactic halo is modelled as an ensemble of independently evolving building-block galaxies with different masses. The single building blocks as well as the disc and satellite dwarfs are treated as well-mixed one-zone systems. Our results indicate that the aforementioned inconsistencies can be resolved and thus NSMs can be the unique r-process site in the Milky Way, provided that the delay-time distributions satisfy the following conditions: (i) a long delay (∼1 Gyr) for the appearance of the first SN Ia (or a slow early increase of its number) and (ii) an additional early component providingof all NSMs with a delay of ∼0.1 Gyr. In our model, r-process-enhanced and r-process-deficient stars in the halo appear to have originated from ultrafaint dwarf-sized and massive building blocks, respectively. Our results also imply that the natal kicks of binary neutron stars have a little impact on the evolution of Eu in the disc.
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影响因子：
4.8
作者：
R. Fern'andez;F. Foucart;J. Lippuner
通讯作者：
R. Fern'andez;F. Foucart;J. Lippuner
超微弱矮星系中的 R 过程富集
影响因子：
4.8
作者：
Tarumi Yuta;Yoshida Naoki;Inoue Shigeki
通讯作者：
Inoue Shigeki
银河系中 r 过程元素的湍流混合
影响因子：
4.8
作者：
P. Beniamini;K. Hotokezaka
通讯作者：
K. Hotokezaka
星系演化的最早阶段
DOI：
10.1086/307006
发表时间：
1998
期刊：
The Astrophysical Journal
影响因子：
--
作者：
C. Chiappini;F. Matteucci;T. Beers;K. Nomoto
通讯作者：
K. Nomoto
DOI：
10.1146/annurev-astro-091918-104453
发表时间：
2019-01
影响因子：
33.3
作者：
J. Simon
通讯作者：
J. Simon