Abstract
The recent aLIGO/aVirgo discovery of gravitational waves from the neutron star merger (NSM) GW170817 and the follow-up kilonova observations have shown that NSMs produce copious amounts of r-process material. However, it is difficult to reconcile the large natal kicks and long average merging times of double-neutron stars (DNSs) with the levels of r-process enrichment seen in ultra-faint dwarf (UFD) galaxies such as Reticulum II and Tucana III. Assuming that such dwarf systems have lost a significant fraction of their stellar mass through tidal stripping, we conclude that contrary to most current models, it is the DNSs with rather large natal kicks but very short merging timescales that can enrich UFD-type galaxies. These binaries are either on highly eccentric orbits or form with very short separations due to an additional mass transfer between the first-born neutron star and a naked helium star, the progenitor of the second neutron star. These DNSs are born with a frequency that agrees with the statistics of the r-process UFDs, and merge well within the virial radius of their host halos, therefore contributing significantly to their r-process enrichment.
| Original language | English (US) |
|---|---|
| Article number | 105 |
| Journal | Astrophysical Journal |
| Volume | 872 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 10 2019 |
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Keywords
- galaxies: dwarf
- stars: evolution
- stars: neutron
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
R-process Enrichment of the Ultra-faint Dwarf Galaxies by Fast-merging Double-neutron Stars. / Safarzadeh, Mohammadtaher; Ramirez-Ruiz, Enrico; Andrews, Jeff J.; MacIas, Phillip; Fragos, Tassos; Scannapieco, Evan.
In: Astrophysical Journal, Vol. 872, No. 1, 105, 10.02.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - R-process Enrichment of the Ultra-faint Dwarf Galaxies by Fast-merging Double-neutron Stars
AU - Safarzadeh, Mohammadtaher
AU - Ramirez-Ruiz, Enrico
AU - Andrews, Jeff J.
AU - MacIas, Phillip
AU - Fragos, Tassos
AU - Scannapieco, Evan
PY - 2019/2/10
Y1 - 2019/2/10
N2 - The recent aLIGO/aVirgo discovery of gravitational waves from the neutron star merger (NSM) GW170817 and the follow-up kilonova observations have shown that NSMs produce copious amounts of r-process material. However, it is difficult to reconcile the large natal kicks and long average merging times of double-neutron stars (DNSs) with the levels of r-process enrichment seen in ultra-faint dwarf (UFD) galaxies such as Reticulum II and Tucana III. Assuming that such dwarf systems have lost a significant fraction of their stellar mass through tidal stripping, we conclude that contrary to most current models, it is the DNSs with rather large natal kicks but very short merging timescales that can enrich UFD-type galaxies. These binaries are either on highly eccentric orbits or form with very short separations due to an additional mass transfer between the first-born neutron star and a naked helium star, the progenitor of the second neutron star. These DNSs are born with a frequency that agrees with the statistics of the r-process UFDs, and merge well within the virial radius of their host halos, therefore contributing significantly to their r-process enrichment.
AB - The recent aLIGO/aVirgo discovery of gravitational waves from the neutron star merger (NSM) GW170817 and the follow-up kilonova observations have shown that NSMs produce copious amounts of r-process material. However, it is difficult to reconcile the large natal kicks and long average merging times of double-neutron stars (DNSs) with the levels of r-process enrichment seen in ultra-faint dwarf (UFD) galaxies such as Reticulum II and Tucana III. Assuming that such dwarf systems have lost a significant fraction of their stellar mass through tidal stripping, we conclude that contrary to most current models, it is the DNSs with rather large natal kicks but very short merging timescales that can enrich UFD-type galaxies. These binaries are either on highly eccentric orbits or form with very short separations due to an additional mass transfer between the first-born neutron star and a naked helium star, the progenitor of the second neutron star. These DNSs are born with a frequency that agrees with the statistics of the r-process UFDs, and merge well within the virial radius of their host halos, therefore contributing significantly to their r-process enrichment.
KW - galaxies: dwarf
KW - stars: evolution
KW - stars: neutron
UR - http://www.scopus.com/inward/record.url?scp=85062039039&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85062039039&partnerID=8YFLogxK
U2 - 10.3847/1538-4357/aafe0e
DO - 10.3847/1538-4357/aafe0e
M3 - Article
AN - SCOPUS:85062039039
VL - 872
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 105
ER -