Evidence for $\gtrsim 4$ Gyr timescales of neutron star mergers from Galactic archaeology

Abstract

The nucleosynthetic site of the rapid ($r$) neutron-capture process is currently being debated. The direct detection of the neutron star merger GW170817, through gravitational waves and electromagnetic radiation, has confirmed such events as important sources of the $r$-process elements. However, chemical evolution models are not able to reproduce the observed chemical abundances in the Milky Way when neutron star mergers are assumed to be the only $r$-process site and realistic time distributions of such events are taken into account. Now for the first time, we combine all the available observational evidence of the Milky Way and its dwarf galaxy satellites to show that the data can only be explained if there are (at least) two distinct $r$-process sites: a quick source with timescales comparable to core-collapse supernovae, $t_{quick}\lesssim 10^8$ yr, and a delayed source with characteristic timescales $t_{delayed}\gtrsim 4$ Gyr. The delayed $r$-process source most probably originates in neutron star mergers, as the timescale fits well with that estimated for GW170817. Given the short timescales of the quick source, it is likely associated with massive stars, though a specific fast-track channel for compact object mergers cannot be excluded at this point. Our approach demonstrates that only by looking at all the available data will we be able to solve the puzzle that is the $r$-process.

Letter accepted in A&A, 6 pages, 3 figures

References in corpus (42)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Multi-messenger Observations of a Binary Neutron Star Merger
• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• Swope Supernova Survey 2017a (SSS17a), the Optical Counterpart to a Gravitational Wave Source
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. II. UV, Optical, and Near-IR Light Curves and Comparison to Kilonova Models
• Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger
• Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis
• Formation of Double Neutron Star Systems
• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• The Combined Ultraviolet, Optical, and Near-Infrared Light Curves of the Kilonova Associated with the Binary Neutron Star Merger GW170817: Unified Data Set, Analytic Models, and Physical Implications
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. IV. Detection of Near-infrared Signatures of r-process Nucleosynthesis with Gemini-South
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-Poor Stars
• Identification of strontium in the merger of two neutron stars
• Kilonova from post-merger ejecta as an optical and near-infrared counterpart of GW170817
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• Galactic Chemical Evolution and solar s-process abundances: dependence on the 13C-pocket structure
• The exotic chemical composition of the Sagittarius dwarf Spheroidal galaxy
• Segue 1: An Unevolved Fossil Galaxy from the Early Universe
• The Chemical Evolution of the Draco Dwarf Spheroidal Galaxy
• The intermediate neutron-capture process and carbon-enhanced metal-poor stars
• Binarity in Carbon-Enhanced Metal-Poor stars
• Complete element abundances of nine stars in the r-process galaxy Reticulum II
• Asteroseismology of solar-type stars
• 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
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale
• Ultra faint dwarfs: probing early cosmic star formation
• The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. VIII. A Comparison to Cosmological Short-duration Gamma-ray Bursts
• Gaia DR2 reveals a star formation burst in the disc 2-3 Gyr ago
• Recovering the star formation rate in the solar neighborhood
• A new delay time distribution for merging neutron stars tested against Galactic and cosmic data
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and stellar population characterization
• The Old Host-Galaxy Environment of SSS17a, the First Electromagnetic Counterpart to a Gravitational Wave Source
• Contribution of Neutron Star Mergers to the R-process Chemical Evolution in the Hierarchical Galaxy Formation
• The Populations of Carina. II. Chemical Enrichment
• Detailed Abundance Analysis of the Brightest Star in Segue 2, the Least Massive Galaxy
• The star formation history in the solar neighborhood as told by massive white dwarfs
• The chemical evolution of r-process elements from neutron star mergers: the role of a 2-phase interstellar medium
• The star formation history of the Sculptor dwarf spheroidal galaxy
• Modelling the chemical evolution of Zr, La, Ce and Eu in the Galactic discs and bulge

Cited by in corpus (32)

• $R$-process enhancements of Gaia-Enceladus in GALAH DR3
• Evidence from Disrupted Halo Dwarfs that $r$-process Enrichment via Neutron Star Mergers is Delayed by $\gtrsim 500$ Myrs
• Horizons: Nuclear Astrophysics in the 2020s and Beyond
• The Most Metal-poor Stars in the Magellanic Clouds are $r$-process Enhanced
• The chemical composition of globular clusters in the Local Group
• Evolution of neutron capture elements in dwarf galaxies
• The R-Process Alliance: Abundance Universality among Some Elements at and between the First and Second R-Process Peaks
• Timing the r-Process Enrichment of the Ultra-Faint Dwarf Galaxy Reticulum II
• Origin of highly $r$-process-enhanced stars in a cosmological zoom-in simulation of a Milky Way-like galaxy
• Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
• Highly r-process enhanced stars in ultra-faint dwarf galaxies
• Star Formation Timescales of the Halo Populations from Asteroseismology and Chemical Abundances
• Galactic chemical evolution of exoplanet host stars: Are high-mass planetary systems young?
• Extremely metal-poor stars in the Fornax and Carina dwarf spheroidal galaxies
• Chemical Evolution of Ytterbium in the Galactic Disk
• Extending the Chemical Reach of the H3 Survey: Detailed Abundances of the Dwarf-galaxy Stellar Stream Wukong/LMS-1
• Gaia-Sausage-Enceladus star formation history as revealed by detailed elemental abundances
• Stellar Signatures of Inhomogeneous Big Bang Nucleosynthesis
• Exploring the chemodynamics of metal-poor stellar populations
• The Gaia-ESO survey: placing constraints on the origin of r-process elements
• Neutron-capture elements in dwarf galaxies III: A homogenized analysis of 13 dwarf spheroidal and ultra-faint galaxies
• Evidence of Gaia Enceladus experiencing at least two passages around the Milky Way
• Chemical Evolution of R-process Elements in Stars (CERES). III. Chemical abundances of neutron capture elements from Ba to Eu
• Peeking beneath the precision floor -- II. Probing the chemo-dynamical histories of the potential globular cluster siblings, NGC 288 and NGC 362
• Europium, we have a problem. Modelling r-process enrichment across Local Group galaxies
• Abundances of disk and bulge giants from high-resolution optical spectra V. Molybdenum -- the p-process element
• Optical darkness in short-duration $\gamma$-ray bursts
• Where has all the $r$-process gone? Timescales for GRB-Kilonovae to Enrich their Host Galaxies
• The R-Process Alliance: Exploring the cosmic scatter among ten r-process sites with stellar abundances
• The Spatially Resolved Properties of the GW170817 Host Galaxy
• Chemical Evolution and Kilonova Implications of Post-Merger Accretion Disk Winds
• Th/Eu abundance ratio of red giants in the Kepler Field