Neutrino-driven winds from neutron star merger remnants

• Published in: Monthly notices of the Royal Astronomical Society 2014-10, Vol.443 (4), p.3134-3156
• Main Authors: Perego, A., Rosswog, S., Cabezón, R. M., Korobkin, O., Käppeli, R., Arcones, A., Liebendörfer, M.
• Format: Article
• Language: English
• Subjects: accretion; accretion discs; Accretion disks; Astrophysics; dense matter; Electromagnetics; Fluid mechanics; hydrodynamics; Luminosity; Neutrinos; Star & galaxy formation; stars: neutron
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stu1352

We present a detailed, three-dimensional hydrodynamic study of the neutrino-driven winds emerging from the remnant of a neutron star merger. Our simulations are performed with the Newtonian, Eulerian code fish, augmented by a detailed, spectral neutrino leakage scheme that accounts for neutrino absorption. Consistent with earlier two-dimensional studies, a strong baryonic wind is blown out along the original binary rotation axis within ≈100 ms. From this model, we compute a lower limit on the expelled mass of 3.5 × 10−3 M⊙, relevant for heavy element nucleosynthesis. Because of stronger neutrino irradiation, the polar regions show substantially larger electron fractions than those at lower latitudes. The polar ejecta produce interesting r-process contributions from A ≈ 80 to about 130, while the more neutron-rich, lower latitude parts produce elements up to the third r-process peak near A ≈ 195. We calculate the properties of electromagnetic transients powered by the radioactivity in the wind, in addition to the ‘macronova’ transient stemming from the dynamic ejecta. The polar regions produce ultraviolet/optical transients reaching luminosities up to 1041 erg s−1, which peak around 1 d in optical and 0.3 d in bolometric luminosity. The lower latitude regions, due to their contamination with high-opacity heavy elements, produce dimmer and more red signals, peaking after ∼2 d in optical and infrared.