r-process Production Sites as inferred from Eu Abundances in Dwarf Galaxies

Abstract

Recent observations of $r$-process material in ultra-faint dwarf galaxies (UFDs) shed light on the sources of these elements. Strong upper limits on the Eu mass in some UFDs combined with detections of much larger masses in a UFD, Reticulum II, and other dwarf galaxies imply that Eu production is dominated by rare events, and that the minimal Eu mass observed in any UFD is approximately the amount of Eu mass produced per event. This is consistent with other independent observations in the Galaxy. We estimate, using a model independent likelihood analysis, the rate and Eu (Fe) mass produced per $r$-process (Fe production) event in dwarf galaxies including classical dwarfs and UFDs. The mass and rate of the Fe production events are consistent with the normal core-collapse supernova~(ccSN) scenario. The Eu mass per event is $3\times 10^{-5}{M}_{\odot }<{\tilde{m}}_{\mathrm{Eu}}<2\times 10^{-4}{M}_{\odot }$, corresponding to a total $r$-process mass per event of $6\times 10^{-3}{M}_{\odot }<{\tilde{m}}_{r-process}<4\times 10^{-2}{M}_{\odot }$. The rate of $r$-process events is $2.5\times 10^{-4}<R_{rp/SN}<1.4\times 10^{-3}$ as compared with the ccSNe rate. These values are consistent with the total Eu mass observed in our own Galaxy, suggesting that the same mechanism is behind the production of $r$-process events in both dwarf galaxies and the Milky Way, and that it may be the dominant mechanism for production of $r$-process elements in the Universe. The results are consistent with neutron star mergers estimates, but cannot rule out other rare core collapse scenarios, provided that they produce a significant amounts of $r$-process material per event.

27 pages, 3 figures. Published in ApJ

References in corpus (28)

• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Cats and Dogs, Hair and A Hero: A Quintet of New Milky Way Companions
• Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• Neutrino-driven winds from neutron star merger remnants
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• The dynamical mass ejection from binary neutron star mergers: Radiation-hydrodynamics study in general relativity
• The rate, luminosity function and time delay of non-Collapsar short GRBs
• A high resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy
• Segue 1: An Unevolved Fossil Galaxy from the Early Universe
• Complete element abundances of nine stars in the r-process galaxy Reticulum II
• Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers
• Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy
• The History of R-Process Enrichment in the Milky Way
• Outflows from accretion disks formed in neutron star mergers: effect of black hole spin
• Simulating cosmic metal enrichment by the first galaxies
• On the Conditions for Neutron-Rich Gamma-Ray Burst Outflows
• The Star Formation Histories of Local Group Dwarf Galaxies III. Characterizing Quenching in Low-Mass Galaxies
• Neutron Star Mergers as the Origin of r-Process Elements in the Galactic Halo Based on the Sub-halo Clustering Scenario
• Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process
• Supernova Fallback: A Possible Site for the r-Process
• Natal Kicks and Time Delays in Merging Neutron Star Binaries - Implications for r-process nucleosynthesis in Ultra Faint Dwarfs and in the Milky Way
• Enrichment history of r-process elements shaped by a merger of neutron star pairs
• Detailed Abundance Analysis of the Brightest Star in Segue 2, the Least Massive Galaxy
• Chemical Feature of Eu abundance in the Draco dwarf spheroidal galaxy
• Neutrino-heated winds from rotating proto-magnetars
• Thermonuclear explosion of rotating massive stars could explain core-collapse supernovae

Cited by in corpus (16)

• The Emergence of a Lanthanide-Rich Kilonova Following the Merger of Two Neutron Stars
• Formation of Double Neutron Star Systems
• Neutron Star Mergers and Nucleosynthesis of Heavy Elements
• Estimating the Contribution of Dynamical Ejecta in the Kilonova Associated with GW170817
• The intermediate r-process in core-collapse supernovae driven by the magneto-rotational instability
• The $R$-Process Alliance: Fourth Data Release from the Search for $r$-Process-Enhanced Stars in the Galactic Halo
• Host galaxies of merging compact objects: mass, star formation rate, metallicity and colours
• Advanced LIGO Constraints on Neutron Star Mergers and R-Process Sites
• Natal Kicks and Time Delays in Merging Neutron Star Binaries - Implications for r-process nucleosynthesis in Ultra Faint Dwarfs and in the Milky Way
• RAVE J203843.2-002333: The first highly r-process-enhanced star identified in the RAVE survey
• On the formation of GW190814
• Observable Features of GW170817 Kilonova Afterglow
• Highly r-process enhanced stars in ultra-faint dwarf galaxies
• Common envelope jets supernova r-process yields can reproduce $[Eu/Fe]$ abundance evolution in the Galaxy
• Binary neutron star merger in common envelope jet supernovae
• GRB 111005A at Z = 0.0133 and the Prospect of Establishing Long-short GRB/GW Association