{
  "id": "2102.04920",
  "version": "v1",
  "published": "2021-02-09T16:23:18.000Z",
  "updated": "2021-02-09T16:23:18.000Z",
  "title": "Nucleosynthesis signatures of neutrino-driven winds from proto-neutron stars: a perspective from chemical evolution models",
  "authors": [
    "Fiorenzo Vincenzo",
    "Todd A. Thompson",
    "David H. Weinberg",
    "Emily J. Griffith",
    "James W. Johnson",
    "Jennifer A. Johnson"
  ],
  "comment": "9 pages, 5 figures",
  "categories": [
    "astro-ph.GA",
    "astro-ph.HE",
    "astro-ph.SR"
  ],
  "abstract": "We test the hypothesis that the observed first-peak (Sr, Y, Zr) and second-peak (Ba) s-process elemental abundances in low metallicity Milky Way stars ($\\text{[Fe/H]} \\lesssim -0.5$), and the abundances of the intervening elements Mo and Ru, can be explained by a pervasive r-process contribution that originates in neutrino-driven winds from highly-magnetic and rapidly rotating proto-neutron stars (proto-NSs). To this end, we construct chemical evolution models that incorporate recent calculations of proto-NS yields in addition to contributions from AGB stars, Type Ia supernovae, and two alternative sets of yields for massive star winds and core collapse supernovae. For non-rotating massive star yields from either set, models without proto-NS winds underpredict the observed s-process peak abundances by $0.3$-$1\\,\\text{dex}$ at low metallicity, and they severely underpredict Mo and Ru at all metallicities. Models that include the additional wind yields predicted for proto-NSs with spin periods $P \\sim 2$-$5\\,\\text{ms}$ fit the observed trends for all these elements well. Alternatively, models that omit proto-NS winds but adopt yields of rapidly rotating massive stars, with $v_{\\rm rot}$ between $150$ and $300\\,\\text{km}\\,\\text{s}^{-1}$, can explain the observed abundance levels reasonably well for $\\text{[Fe/H]}<-2$. These models overpredict [Sr/Fe] and [Mo/Fe] at higher metallicities, but with a tuned dependence of $v_{\\rm rot}$ on stellar metallicity they might achieve an acceptable fit at all [Fe/H]. If many proto-NSs are born with strong magnetic fields and short spin periods, then their neutrino-driven winds provide a natural source for Sr, Y, Zr, Mo, Ru, and Ba in low metallicity stellar populations. Spherical winds from unmagnetized proto-NSs, on the other hand, overproduce the observed Sr, Y, and Zr abundances by a large factor.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2021-02-09T16:23:18.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "chemical evolution models",
      "neutrino-driven winds",
      "proto-neutron stars",
      "nucleosynthesis signatures",
      "low metallicity milky way stars"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 9,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}