2016/08/05 by Yutaka Komiya, Toshikazu Shigeyama · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Ejecta #Galaxy #Galaxy formation and evolution #Gamma-ray bursts and supernovae #Intergalactic star #Intergalactic travel #Milky Way #Protogalaxy #Pulsars and Gravitational Waves Research #Star formation #Stars #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/0004-637x/830/2/76
11 pages, 7 figures, ApJ accepted
arxiv created 2016/08/05 · openalex created_date 2016/08/23 · openalex publication_date 2016/10/13 · arxiv updated 2016/10/19 · openalex updated_date 2026/08/05
ABSTRACT The main astronomical source of r-process elements has not yet been identified. One plausible site is neutron star mergers (NSMs), but from the perspective of the Galactic chemical evolution, it has been pointed out that NSMs cannot reproduce the observed r-process abundance distribution of metal-poor stars at . Recently, Tsujimoto & Shigeyama pointed out that NSM ejecta can spread into a much larger volume than ejecta from a supernova. We re-examine the enrichment of r-process elements by NSMs considering this difference in propagation using the chemical evolution model under the hierarchical galaxy formation. The observed r-process enhanced stars around are reproduced if the star formation efficiency is lower for low-mass galaxies under a realistic delay-time distribution for NSMs. We show that a significant fraction of NSM ejecta escape from its host proto-galaxy to pollute intergalactic matter and other proto-galaxies. The propagation of r-process elements over proto-galaxies changes the abundance distribution at and obtains distribution compatible with observations of the Milky Way halo stars. In particular, the pre-enrichment of intergalactic medium explains the observed scarcity of extremely metal-poor stars without Ba and abundance distribution of r-process elements at .