Collapsars as a major source of r-process elements


The production of elements by rapid neutron capture (r-process) in neutron-star mergers is expected theoretically and is supported by multimessenger observations1,2,3 of gravitational-wave event GW170817: this production route is in principle sufficient to account for most of the r-process elements in the Universe4. Analysis of the kilonova that accompanied GW170817 identified5,6 delayed outflows from a remnant accretion disk formed around the newly born black hole7,8,9,10 as the dominant source of heavy r-process material from that event9,11. Similar accretion disks are expected to form in collapsars (the supernova-triggering collapse of rapidly rotating massive stars), which have previously been speculated to produce r-process elements12,13. Recent observations of stars rich in such elements in the dwarf galaxy Reticulum II14, as well as the Galactic chemical enrichment of europium relative to iron over longer timescales15,16, are more consistent with rare supernovae acting at low stellar metallicities than with neutron-star mergers. Here we report simulations that show that collapsar accretion disks yield sufficient r-process elements to explain observed abundances in the Universe. Although these supernovae are rarer than neutron-star mergers, the larger amount of material ejected per event compensates for the lower rate of occurrence. We calculate that collapsars may supply more than 80 per cent of the r-process content of the Universe.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Various stages of collapsar accretion and nucleosynthetic yields.
Fig. 2: Nucleosynthesis yields at the simulated collapsar accretion stages.
Fig. 3: The signatures of r-process nucleosynthesis in GRB supernovae.

Data availability

No datasets were generated or analysed during the current study.

Code availability

A public version of the GRMHD code used to conduct the simulations of collapsar accretion disks is available through the Einstein Toolkit at; the framework for the recovery of primitive variables used here is available at The nuclear reaction network employed for the r-process nucleosynthesis calculations is available at The radiation transport code used to explore r-process signatures in GRB supernovae is not currently available as it is in the process of being readied and approved for public release.


  1. 1.

    Abbott, B. P. et al. GW170817: observation of gravitational waves from a binary neutron star inspiral. Phys. Rev. Lett. 119, 161101 (2017).

    ADS  CAS  Google Scholar 

  2. 2.

    Coulter, D. A. et al. Swope Supernova Survey 2017a (SSS17a), the optical counterpart to a gravitational wave source. Science 358, 1556–1558 (2017).

    ADS  CAS  Google Scholar 

  3. 3.

    Soares-Santos, M. et al. The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. I. Discovery of the optical counterpart using the Dark Energy Camera. Astrophys. J. 848, L16 (2017).

    ADS  Google Scholar 

  4. 4.

    Kasen, D., Metzger, B., Barnes, J., Quataert, E. & Ramirez-Ruiz, E. Origin of the heavy elements in binary neutron-star mergers from a gravitational-wave event. Nature 551, 80–84 (2017).

    ADS  Google Scholar 

  5. 5.

    Cowperthwaite, P. S. et al. The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. II. UV, optical, and near-infrared light curves and comparison to kilonova models. Astrophys. J. 848, L17 (2017).

    ADS  Google Scholar 

  6. 6.

    Radice, D., Perego, A., Zappa, F. & Bernuzzi, S. GW170817: joint constraint on the neutron star equation of state from multimessenger observations. Astrophys. J. 852, L29 (2018).

    ADS  Google Scholar 

  7. 7.

    Fernández, R. & Metzger, B. D. Delayed outflows from black hole accretion tori following neutron star binary coalescence. Mon. Not. R. Astron. Soc. 435, 502–517 (2013).

    ADS  Google Scholar 

  8. 8.

    Just, O., Bauswein, A., Pulpillo, R. A., Goriely, S. & Janka, H.-T. Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers. Mon. Not. R. Astron. Soc. 448, 541–567 (2015).

    ADS  CAS  Google Scholar 

  9. 9.

    Siegel, D. M. & Metzger, B. D. Three-dimensional general-relativistic magnetohydrodynamic simulations of remnant accretion disks from neutron star mergers: outflows and r-process nucleosynthesis. Phys. Rev. Lett. 119, 231102 (2017).

    ADS  Google Scholar 

  10. 10.

    Fernández, R., Tchekhovskoy, A., Quataert, E., Foucart, F. & Kasen, D. Long-term GRMHD simulations of neutron star merger accretion disks: implications for electromagnetic counterparts. Mon. Not. R. Astron. Soc. 482, 3373–3393 (2019).

    ADS  Google Scholar 

  11. 11.

    Siegel, D. M. & Metzger, B. D. Three-dimensional GRMHD simulations of neutrino-cooled accretion disks from neutron star mergers. Astrophys. J. 858, 52 (2018).

    ADS  Google Scholar 

  12. 12.

    MacFadyen, A. I. & Woosley, S. E. Collapsars: gamma-ray bursts and explosions in “failed supernovae”. Astrophys. J. 524, 262–289 (1999).

    ADS  CAS  Google Scholar 

  13. 13.

    Kohri, K., Narayan, R. & Piran, T. Neutrino-dominated accretion and supernovae. Astrophys. J. 629, 341–361 (2005).

    ADS  Google Scholar 

  14. 14.

    Ji, A. P., Frebel, A., Chiti, A. & Simon, J. D. R-process enrichment from a single event in an ancient dwarf galaxy. Nature 531, 610–613 (2016).

    ADS  CAS  Google Scholar 

  15. 15.

    Côté, B. et al. Advanced LIGO constraints on neutron star mergers and r-process sites. Astrophys. J. 836, 230 (2017).

    ADS  Google Scholar 

  16. 16.

    Hotokezaka, K., Beniamini, P. & Piran, T. Neutron star mergers as sites of r-process nucleosynthesis and short gamma-ray bursts. Int. J. Mod. Phys. D 27, 1842005 (2018).

    ADS  MathSciNet  CAS  Google Scholar 

  17. 17.

    Pruet, J., Thompson, T. A. & Hoffman, R. D. Nucleosynthesis in outflows from the inner regions of collapsars. Astrophys. J. 606, 1006–1018 (2004).

    ADS  CAS  Google Scholar 

  18. 18.

    Surman, R., McLaughlin, G. C. & Sabbatino, N. Nucleosynthesis of nickel-56 from gamma-ray burst accretion disks. Astrophys. J. 743, 155 (2011).

    ADS  Google Scholar 

  19. 19.

    Beloborodov, A. M. Nuclear composition of gamma-ray burst fireballs. Astrophys. J. 588, 931–944 (2003).

    ADS  CAS  Google Scholar 

  20. 20.

    Dessart, L., Burrows, A., Livne, E. & Ott, C. D. The proto-neutron star phase of the collapsar model and the route to long-soft gamma-ray bursts and hypernovae. Astrophys. J. 673, L43–L46 (2008).

    ADS  CAS  Google Scholar 

  21. 21.

    Mösta, P. et al. r-process nucleosynthesis from three-dimensional magnetorotational core-collapse supernovae. Astrophys. J. 864, 171 (2018).

    ADS  Google Scholar 

  22. 22.

    Ghirlanda, G., Nava, L., Ghisellini, G., Celotti, A. & Firmani, C. Short versus long gamma-ray bursts: spectra, energetics, and luminosities. Astron. Astrophys. 496, 585–595 (2009).

    ADS  CAS  Google Scholar 

  23. 23.

    Kasen, D., Badnell, N. R. & Barnes, J. Opacities and spectra of the r-process ejecta from neutron star mergers. Astrophys. J. 774, 25 (2013).

    ADS  CAS  Google Scholar 

  24. 24.

    Winteler, C. et al. Magnetorotationally driven supernovae as the origin of early galaxy r-process elements? Astrophys. J. 750, L22 (2012).

    ADS  Google Scholar 

  25. 25.

    Shen, S. et al. The history of r-process enrichment in the Milky Way. Astrophys. J. 807, 115 (2015).

    ADS  Google Scholar 

  26. 26.

    van de Voort, F., Quataert, E., Hopkins, P. F., Kereš, D. & Faucher-Giguère, C.-A. Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy. Mon. Not. R. Astron. Soc. 447, 140–148 (2015).

    ADS  Google Scholar 

  27. 27.

    Ramirez-Ruiz, E. et al. Compact stellar binary assembly in the first nuclear star clusters and r-process synthesis in the early universe. Astrophys. J. 802, L22 (2015).

    ADS  Google Scholar 

  28. 28.

    Stanek, K. Z. et al. Protecting life in the Milky Way: metals keep the GRBs away. Acta Astron. 56, 333–345 (2006).

    ADS  Google Scholar 

  29. 29.

    Sneden, C. et al. The extremely metal-poor, neutron capture-rich star CS 22892–052: a comprehensive abundance analysis. Astrophys. J. 591, 936–953 (2003).

    ADS  CAS  Google Scholar 

  30. 30.

    Beniamini, P., Hotokezaka, K. & Piran, T. Natal kicks and time delays in merging neutron star binaries: implications for r-process nucleosynthesis in ultra-faint dwarfs and in the Milky Way. Astrophys. J. 829, L13 (2016).

    ADS  Google Scholar 

  31. 31.

    Siegel, D. M., Mösta, P., Desai, D. & Wu, S. Recovery schemes for primitive variables in general-relativistic magnetohydrodynamics. Astrophys. J. 859, 71 (2018).

    ADS  Google Scholar 

  32. 32.

    Mösta, P. et al. GRHydro: a new open-source general-relativistic magnetohydrodynamics code for the Einstein toolkit. Class. Quantum Gravity 31, 015005 (2014).

    ADS  MATH  Google Scholar 

  33. 33.

    Löffler, F. et al. The Einstein Toolkit: a community computational infrastructure for relativistic astrophysics. Class. Quantum Gravity 29, 115001 (2012).

    ADS  MATH  Google Scholar 

  34. 34.

    Timmes, F. X. & Arnett, D. The accuracy, consistency, and speed of five equations of state for stellar hydrodynamics. Astrophys. J. Suppl. Ser. 125, 277–294 (1999).

    ADS  CAS  Google Scholar 

  35. 35.

    Timmes, F. X. & Swesty, F. D. The accuracy, consistency, and speed of an electron-positron equation of state based on table interpolation of the Helmholtz free energy. Astrophys. J. Suppl. Ser. 126, 501–516 (2000).

    ADS  Google Scholar 

  36. 36.

    Di Matteo, T., Perna, R. & Narayan, R. Neutrino trapping and accretion models for gamma-ray bursts. Astrophys. J. 579, 706–715 (2002).

    ADS  Google Scholar 

  37. 37.

    Lippuner, J. & Roberts, L. F. SkyNet: a modular nuclear reaction network library. Astrophys. J. Suppl. Ser. 233, 18 (2017).

    ADS  Google Scholar 

  38. 38.

    Velikhov, E. P. Stability of an ideally conducting liquid flowing between cylinders rotating in a magnetic field. Sov. Phys. JETP 36, 995–998 (1959).

    MathSciNet  Google Scholar 

  39. 39.

    Chandrasekhar, S. The stability of non-dissipative Couette flow in hydromagnetics. Proc. Natl Acad. Sci. USA 46, 253–257 (1960).

    ADS  MathSciNet  CAS  MATH  Google Scholar 

  40. 40.

    Balbus, S. A. & Hawley, J. F. A powerful local shear instability in weakly magnetized disks. I. Linear analysis. Astrophys. J. 376, 214–222 (1991); A powerful local shear instability in weakly magnetized disks. II. Nonlinear evolution. Astrophys. J. 376, 223–233 (1991).

    ADS  Google Scholar 

  41. 41.

    Balbus, S. A. & Hawley, J. F. Instability, turbulence, and enhanced transport in accretion disks. Rev. Mod. Phys. 70, 1–53 (1998).

    ADS  Google Scholar 

  42. 42.

    Balbus, S. A. Enhanced angular momentum transport in accretion disks. Annu. Rev. Astron. Astrophys. 41, 555–597 (2003).

    ADS  Google Scholar 

  43. 43.

    Siegel, D. M., Ciolfi, R., Harte, A. I. & Rezzolla, L. Magnetorotational instability in relativistic hypermassive neutron stars. Phys. Rev. D 87, 121302(R) (2013).

    ADS  Google Scholar 

  44. 44.

    Kiuchi, K. et al. High resolution magnetohydrodynamic simulation of black hole-neutron star merger: mass ejection and short gamma ray bursts. Phys. Rev. D 92, 064034 (2015).

    ADS  Google Scholar 

  45. 45.

    Kiuchi, K., Kyutoku, K., Sekiguchi, Y. & Shibata, M. Global simulations of strongly magnetized remnant massive neutron stars formed in binary neutron star mergers. Phys. Rev. D 97, 124039 (2018).

    ADS  CAS  Google Scholar 

  46. 46.

    Cowling, T. G. The magnetic field of sunspots. Mon. Not. R. Astron. Soc. 94, 39–48 (1933).

    ADS  MATH  Google Scholar 

  47. 47.

    Nakamura, K., Kajino, T., Mathews, G. J., Sato, S. & Harikae, S. r-process nucleosynthesis in the MHD+neutrino-heated collapsar jet. Astron. Astrophys. 582, A34 (2015).

    ADS  Google Scholar 

  48. 48.

    Shakura, N. I. & Sunyaev, R. A. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973).

    ADS  Google Scholar 

  49. 49.

    Penna, R. F., Sadowski, A., Kulkarni, A. K. & Narayan, R. The Shakura-Sunyaev viscosity prescription with variable α(r). Mon. Not. R. Astron. Soc. 428, 2255–2274 (2013).

    ADS  Google Scholar 

  50. 50.

    Popham, R., Woosley, S. E. & Fryer, C. Hyperaccreting black holes and gamma-ray bursts. Astrophys. J. 518, 356–374 (1999).

    ADS  CAS  Google Scholar 

  51. 51.

    Narayan, R., Piran, T. & Kumar, P. Accretion models of gamma-ray bursts. Astrophys. J. 557, 949–957 (2001).

    ADS  Google Scholar 

  52. 52.

    Chen, W.-X. & Beloborodov, A. M. Neutrino-cooled accretion disks around spinning black holes. Astrophys. J. 657, 383–399 (2007).

    ADS  CAS  Google Scholar 

  53. 53.

    Metzger, B. D., Piro, A. L. & Quataert, E. Time-dependent models of accretion discs formed from compact object mergers. Mon. Not. R. Astron. Soc. 390, 781–797 (2008).

    ADS  CAS  Google Scholar 

  54. 54.

    MacFadyen, A. I., Woosley, S. E. & Heger, A. Supernovae, jets, and collapsars. Astrophys. J. 550, 410–425 (2001).

    ADS  Google Scholar 

  55. 55.

    Mazzali, P. A. et al. Models for the type Ic hypernova SN 2003lw associated with GRB 031203. Astrophys. J. 645, 1323–1330 (2006).

    ADS  CAS  Google Scholar 

  56. 56.

    Cano, Z., Johansson Andreas, K. G. & Maeda, K. A self-consistent analytical magnetar model: the luminosity of γ-ray burst supernovae is powered by radioactivity. Mon. Not. R. Astron. Soc. 457, 2761–2772 (2016).

    ADS  CAS  Google Scholar 

  57. 57.

    Woosley, S. E. & Hoffman, R. D. The alpha-process and the r-process. Astrophys. J. 395, 202–239 (1992).

    ADS  CAS  Google Scholar 

  58. 58.

    Roberts, L. F., Woosley, S. E. & Hoffman, R. D. Integrated nucleosynthesis in neutrino-driven winds. Astrophys. J. 722, 954–967 (2010).

    ADS  CAS  Google Scholar 

  59. 59.

    Woosley, S. E. & Bloom, J. S. The supernova gamma-ray burst connection. Annu. Rev. Astron. Astrophys. 44, 507–556 (2006).

    ADS  CAS  Google Scholar 

  60. 60.

    Qian, Y. & Woosley, S. E. Nucleosynthesis in neutrino-driven winds. I. The physical conditions. Astrophys. J. 471, 331 (1996).

    ADS  CAS  Google Scholar 

  61. 61.

    Thompson, T. A., Burrows, A. & Meyer, B. S. The physics of proto-neutron star winds: implications for r-process nucleosynthesis. Astrophys. J. 562, 887–908 (2001).

    ADS  CAS  Google Scholar 

  62. 62.

    Roberts, L. F., Reddy, S. & Shen, G. Medium modification of the charged-current neutrino opacity and its implications. Phys. Rev. C 86, 065803 (2012).

    ADS  Google Scholar 

  63. 63.

    Martínez-Pinedo, G., Fischer, T., Lohs, A. & Huther, L. Charged-current weak interaction processes in hot and dense matter and its impact on the spectra of neutrinos emitted from protoneutron star cooling. Phys. Rev. Lett. 109, 251104 (2012).

    ADS  Google Scholar 

  64. 64.

    Thompson, T. A. Magnetic protoneutron star winds and r-process nucleosynthesis. Astrophys. J. 585, L33–L36 (2003).

    ADS  CAS  Google Scholar 

  65. 65.

    Thompson, T. A. & ud-Doula, A. High-entropy ejections from magnetized proto-neutron star winds: implications for heavy element nucleosynthesis. Mon. Not. R. Astron. Soc. 476, 5502–5515 (2018).

    ADS  CAS  Google Scholar 

  66. 66.

    Wallner, A. et al. Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis. Nat. Commun. 6, 5956 (2015).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  67. 67.

    Macias, P. & Ramirez-Ruiz, E. A stringent limit on the mass production rate of r-process elements in the Milky Way. Astrophys. J. 860, 89 (2018).

    ADS  Google Scholar 

  68. 68.

    Thompson, T. A., Chang, P. & Quataert, E. Magnetar spin-down, hyperenergetic supernovae, and gamma-ray bursts. Astrophys. J. 611, 380–393 (2004).

    ADS  CAS  Google Scholar 

  69. 69.

    Metzger, B. D., Thompson, T. A. & Quataert, E. On the conditions for neutron-rich gamma-ray burst outflows. Astrophys. J. 676, 1130–1150 (2008).

    ADS  Google Scholar 

  70. 70.

    Mösta, P. et al. Magnetorotational core-collapse supernovae in three dimensions. Astrophys. J. 785, L29 (2014).

    ADS  Google Scholar 

  71. 71.

    Halevi, G. & Mösta, P. r-Process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments. Mon. Not. R. Astron. Soc. 477, 2366–2375 (2018).

    ADS  CAS  Google Scholar 

  72. 72.

    Fujimoto, S., Hashimoto, M., Kotake, K. & Yamada, S. Heavy-element nucleosynthesis in a collapsar. Astrophys. J. 656, 382–392 (2007).

    ADS  CAS  Google Scholar 

  73. 73.

    Ono, M., Hashimoto, M., Fujimoto, S., Kotake, K. & Yamada, S. Explosive nucleosynthesis in magnetohydrodynamical jets from collapsars. II — Heavy-element nucleosynthesis of s, p, r-processes. Prog. Theor. Phys. 128, 741–765 (2012).

    ADS  CAS  Google Scholar 

  74. 74.

    Hayakawa, T. & Maeda, K. A collapsar model with disk wind: implications for supernovae associated with gamma-ray bursts. Astrophys. J. 854, 43 (2018).

    ADS  Google Scholar 

  75. 75.

    Soker, N. & Gilkis, A. Magnetar-powered superluminous supernovae must first be exploded by jets. Astrophys. J. 851, 95 (2017).

    ADS  Google Scholar 

  76. 76.

    Hjorth, J. & Bloom, J. S. in Gamma-Ray Bursts (eds Kouveliotou, C. et al.) 169–190 (Cambridge Univ. Press, Cambridge, 2012).

  77. 77.

    Fujimoto, S.-i., Kotake, K., Yamada, S., Hashimoto, M.-a. & Sato, K. Magnetohydrodynamic simulations of a rotating massive star collapsing to a black hole. Astrophys. J. 644, 1040–1055 (2006).

    ADS  CAS  Google Scholar 

  78. 78.

    Uzdensky, D. A. & MacFadyen, A. I. Magnetar-driven magnetic tower as a model for gamma-ray bursts and asymmetric supernovae. Astrophys. J. 669, 546–560 (2007).

    ADS  CAS  Google Scholar 

  79. 79.

    Morsony, B. J., Lazzati, D. & Begelman, M. C. Temporal and angular properties of gamma-ray burst jets emerging from massive stars. Astrophys. J. 665, 569–598 (2007).

    ADS  Google Scholar 

  80. 80.

    Bucciantini, N., Quataert, E., Arons, J., Metzger, B. D. & Thompson, T. A. Relativistic jets and long-duration gamma-ray bursts from the birth of magnetars. Mon. Not. R. Astron. Soc. 383, L25–L29 (2008).

    ADS  Google Scholar 

  81. 81.

    Lazzati, D., Perna, R. & Begelman, M. C. X-ray flares, neutrino-cooled discs and the dynamics of late accretion in gamma-ray burst engines. Mon. Not. R. Astron. Soc. 388, L15–L19 (2008).

    ADS  Google Scholar 

  82. 82.

    Kumar, P., Narayan, R. & Johnson, J. L. Mass fall-back and accretion in the central engine of gamma-ray bursts. Mon. Not. R. Astron. Soc. 388, 1729–1742 (2008).

    ADS  CAS  Google Scholar 

  83. 83.

    Nagakura, H., Ito, H., Kiuchi, K. & Yamada, S. Jet propagations, breakouts, and photospheric emissions in collapsing massive progenitors of long-duration gamma-ray bursts. Astrophys. J. 731, 80 (2011).

    ADS  Google Scholar 

  84. 84.

    Lindner, C. C., Milosavljević, M., Shen, R. & Kumar, P. Simulations of accretion powered supernovae in the progenitors of gamma-ray bursts. Astrophys. J. 750, 163 (2012).

    ADS  Google Scholar 

  85. 85.

    López-Cámara, D., Morsony, B. J., Begelman, M. C. & Lazzati, D. Three-dimensional adaptive mesh refinement simulations of long-duration gamma-ray burst jets inside massive progenitor stars. Astrophys. J. 767, 19 (2013).

    ADS  Google Scholar 

  86. 86.

    Batta, A. & Lee, W. H. Cooling-induced structure formation and evolution in collapsars. Mon. Not. R. Astron. Soc. 437, 2412–2429 (2014).

    ADS  Google Scholar 

  87. 87.

    Mazzali, P. A., McFadyen, A. I., Woosley, S. E., Pian, E. & Tanaka, M. An upper limit to the energy of gamma-ray bursts indicates that GRBs/SNe are powered by magnetars. Mon. Not. R. Astron. Soc. 443, 67–71 (2014).

    ADS  Google Scholar 

  88. 88.

    Maeda, K. & Nomoto, K. Bipolar supernova explosions: nucleosynthesis and implications for abundances in extremely metal-poor stars. Astrophys. J. 598, 1163–1200 (2003).

    ADS  CAS  Google Scholar 

  89. 89.

    Fryer, C. L., Young, P. A. & Hungerford, A. L. Explosive nucleosynthesis from gamma-ray burst and hypernova progenitors: direct collapse versus fallback. Astrophys. J. 650, 1028–1047 (2006).

    ADS  CAS  Google Scholar 

  90. 90.

    Maeda, K. & Tominaga, N. Nucleosynthesis of 56Ni in wind-driven supernova explosions and constraints on the central engine of gamma-ray bursts. Mon. Not. R. Astron. Soc. 394, 1317–1324 (2009).

    ADS  CAS  Google Scholar 

  91. 91.

    Barnes, J. et al. A GRB and broad-lined type Ic supernova from a single central engine. Astrophys. J. 860, 38 (2018).

    ADS  Google Scholar 

  92. 92.

    Caballero, O. L., McLaughlin, G. C. & Surman, R. Neutrino spectra from accretion disks: neutrino general relativistic effects and the consequences for nucleosynthesis. Astrophys. J. 745, 170 (2012).

    ADS  Google Scholar 

  93. 93.

    Vlasov, A. D., Metzger, B. D., Lippuner, J., Roberts, L. F. & Thompson, T. A. Neutrino-heated winds from millisecond protomagnetars as sources of the weak r-process. Mon. Not. R. Astron. Soc. 468, 1522–1533 (2017).

    ADS  CAS  Google Scholar 

  94. 94.

    Heger, A., Langer, N. & Woosley, S. E. Presupernova evolution of rotating massive stars. I. Numerical method and evolution of the internal stellar structure. Astrophys. J. 528, 368–396 (2000).

    ADS  CAS  Google Scholar 

  95. 95.

    Bardeen, J. M., Press, W. H. & Teukolsky, S. A. Rotating black holes: locally nonrotating frames, energy extraction, and scalar synchrotron radiation. Astrophys. J. 178, 347–370 (1972).

    ADS  Google Scholar 

  96. 96.

    Bromberg, O., Nakar, E., Piran, T. & Sari, R. An observational imprint of the collapsar model of long gamma-ray bursts. Astrophys. J. 749, 110 (2012).

    ADS  Google Scholar 

  97. 97.

    Sobacchi, E., Granot, J., Bromberg, O. & Sormani, M. C. A common central engine for long gamma-ray bursts and type Ib/c supernovae. Mon. Not. R. Astron. Soc. 472, 616–627 (2017).

    ADS  CAS  Google Scholar 

  98. 98.

    Bhat, P. N. et al. The third Fermi GBM gamma-ray burst catalog: the first six years. Astrophys. J. Suppl. Ser. 223, 28 (2016).

    ADS  Google Scholar 

  99. 99.

    Drout, M. R. et al. Light curves of the neutron star merger GW170817/SSS17a: implications for r-process nucleosynthesis. Science 358, 1570–1574 (2017).

    ADS  CAS  Google Scholar 

  100. 100.

    Tanvir, N. R. et al. The emergence of a lanthanide-rich kilonova following the merger of two neutron stars. Astrophys. J. 848, L27 (2017).

    ADS  Google Scholar 

  101. 101.

    Côté, B. et al. The origin of r-process elements in the Milky Way. Astrophys. J. 855, 99 (2018).

    ADS  Google Scholar 

  102. 102.

    Barnes, J., Kasen, D., Wu, M.-R. & Martínez-Pinedo, G. Radioactivity and thermalization in the ejecta of compact object mergers and their impact on kilonova light curves. Astrophys. J. 829, 110 (2016).

    ADS  Google Scholar 

  103. 103.

    Li, Y., Zhang, B. & Lü, H.-J. A comparative study of long and short GRBs. I. Overlapping properties. Astrophys. J. Suppl. Ser. 227, 7 (2016).

    ADS  Google Scholar 

  104. 104.

    Tchekhovskoy, A. & Giannios, D. Magnetic flux of progenitor stars sets gamma-ray burst luminosity and variability. Mon. Not. R. Astron. Soc. 447, 327–344 (2015).

    ADS  CAS  Google Scholar 

  105. 105.

    Wanderman, D. & Piran, T. The rate, luminosity function and time delay of non-collapsar short GRBs. Mon. Not. R. Astron. Soc. 448, 3026–3037 (2015).

    ADS  CAS  Google Scholar 

  106. 106.

    Wanderman, D. & Piran, T. The luminosity function and the rate of Swift’s gamma-ray bursts. Mon. Not. R. Astron. Soc. 406, 1944–1958 (2010).

    ADS  Google Scholar 

  107. 107.

    Berger, E. Short-duration gamma-ray bursts. Annu. Rev. Astron. Astrophys. 52, 43–105 (2014).

    ADS  Google Scholar 

  108. 108.

    Liang, E., Zhang, B., Virgili, F. & Dai, Z. G. Low-luminosity gamma-ray bursts as a unique population: luminosity function, local rate, and beaming factor. Astrophys. J. 662, 1111–1118 (2007).

    ADS  Google Scholar 

  109. 109.

    Melandri, A. et al. Diversity of gamma-ray burst energetics vs. supernova homogeneity: SN 2013cq associated with GRB 130427A. Astron. Astrophys. 567, A29 (2014).

    Google Scholar 

  110. 110.

    Arnould, M., Goriely, S. & Takahashi, K. The r-process of stellar nucleosynthesis: astrophysics and nuclear physics achievements and mysteries. Phys. Rep. 450, 97–213 (2007).

    ADS  CAS  Google Scholar 

  111. 111.

    Kistler, M. D., Yüksel, H., Beacom, J. F. & Stanek, K. Z. An unexpectedly swift rise in the gamma-ray burst rate. Astrophys. J. 673, L119–L122 (2008).

    ADS  Google Scholar 

  112. 112.

    Goldstein, A., Connaughton, V., Briggs, M. S. & Burns, E. Estimating long GRB jet opening angles and rest-frame energetics. Astrophys. J. 818, 18 (2016).

    ADS  Google Scholar 

  113. 113.

    Perley, D. A. et al. The Swift GRB host galaxy legacy survey. II. Rest-frame near-IR luminosity distribution and evidence for a near-solar metallicity threshold. Astrophys. J. 817, 8 (2016).

    ADS  Google Scholar 

  114. 114.

    Abolfathi, B. et al. The fourteenth data release of the Sloan Digital Sky Survey: first spectroscopic data from the extended baryon oscillation spectroscopic survey and from the second phase of the Apache Point Observatory galactic evolution experiment. Astrophys. J. Suppl. Ser. 235, 42 (2018).

    ADS  Google Scholar 

  115. 115.

    Metzger, B. D. et al. Electromagnetic counterparts of compact object mergers powered by the radioactive decay of r-process nuclei. Mon. Not. R. Astron. Soc. 406, 2650–2662 (2010).

    ADS  Google Scholar 

  116. 116.

    Tanaka, M. et al. Properties of kilonovae from dynamical and post-merger ejecta of neutron star mergers. Astrophys. J. 852, 109 (2018).

    ADS  Google Scholar 

  117. 117.

    Barnes, J. & Kasen, D. Effect of a high opacity on the light curves of radioactively powered transients from compact object mergers. Astrophys. J. 775, 18 (2013).

    ADS  Google Scholar 

  118. 118.

    Tanaka, M. & Hotokezaka, K. Radiative transfer simulations of neutron star merger ejecta. Astrophys. J. 775, 113 (2013).

    ADS  Google Scholar 

  119. 119.

    Wollaeger, R. T. et al. Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers. Mon. Not. R. Astron. Soc. 478, 3298–3334 (2018).

    ADS  CAS  Google Scholar 

  120. 120.

    Kasen, D., Thomas, R. C. & Nugent, P. Time-dependent Monte Carlo radiative transfer calculations for three-dimensional supernova spectra, light curves, and polarization. Astrophys. J. 651, 366–380 (2006).

    ADS  Google Scholar 

  121. 121.

    Kurucz, R. L. & Bell, B. Atomic Line List (Smithsonian Astrophysical Observatory, Cambridge, 1995).

    Google Scholar 

  122. 122.

    Bufano, F. et al. The highly energetic expansion of SN 2010bh associated with GRB 100316D. Astrophys. J. 753, 67 (2012).

    ADS  Google Scholar 

  123. 123.

    Villar, V. A. et al. Spitzer Space Telescope infrared observations of the binary neutron star merger GW170817. Astrophys. J. 862, L11 (2018).

    ADS  Google Scholar 

  124. 124.

    Wu, M.-R., Barnes, J., Martinez-Pinedo, G. & Metzger, B. D. Fingerprints of heavy-element nucleosynthesis in the late-time lightcurves of kilonovae. Phys. Rev. Lett. 122, 062701 (2019).

  125. 125.

    Côté, B., O’Shea, B. W., Ritter, C., Herwig, F. & Venn, K. A. The impact of modeling assumptions in galactic chemical evolution models. Astrophys. J. 835, 128 (2017).

    ADS  Google Scholar 

  126. 126.

    Komiya, Y. & Shigeyama, T. Contribution of neutron star mergers to the r-process chemical evolution in the hierarchical galaxy formation. Astrophys. J. 830, 76 (2016).

    ADS  Google Scholar 

  127. 127.

    Cescutti, G., Romano, D., Matteucci, F., Chiappini, C. & Hirschi, R. The role of neutron star mergers in the chemical evolution of the Galactic halo. Astron. Astrophys. 577, A139 (2015).

    ADS  Google Scholar 

  128. 128.

    Wehmeyer, B., Pignatari, M. & Thielemann, F.-K. Galactic evolution of rapid neutron capture process abundances: the inhomogeneous approach. Mon. Not. R. Astron. Soc. 452, 1970–1981 (2015).

    ADS  CAS  Google Scholar 

  129. 129.

    Hirai, Y. et al. Enrichment of r-process elements in dwarf spheroidal galaxies in chemo-dynamical evolution model. Astrophys. J. 814, 41 (2015).

    ADS  Google Scholar 

  130. 130.

    Ishimaru, Y., Wanajo, S. & Prantzos, N. Neutron star mergers as the origin of r-process elements in the Galactic halo based on the sub-halo clustering scenario. Astrophys. J. 804, L35 (2015).

    ADS  Google Scholar 

  131. 131.

    Burris, D. L. et al. Neutron-capture elements in the early Galaxy: insights from a large sample of metal-poor giants. Astrophys. J. 544, 302–319 (2000).

    ADS  CAS  Google Scholar 

  132. 132.

    Battistini, C. & Bensby, T. The origin and evolution of r- and s-process elements in the Milky Way stellar disk. Astron. Astrophys. 586, A49 (2016).

    ADS  Google Scholar 

  133. 133.

    Madau, P. & Fragos, T. Radiation backgrounds at cosmic dawn: X-rays from compact binaries. Astrophys. J. 840, 39 (2017).

    ADS  Google Scholar 

  134. 134.

    Kopparapu, R. K. et al. Host galaxies catalog used in LIGO searches for compact binary coalescence events. Astrophys. J. 675, 1459–1467 (2008).

    ADS  CAS  Google Scholar 

  135. 135.

    Li, W. et al. Nearby supernova rates from the Lick Observatory Supernova Search – III. The rate-size relation, and the rates as a function of galaxy Hubble type and colour. Mon. Not. R. Astron. Soc. 412, 1473–1507 (2011).

    ADS  Google Scholar 

  136. 136.

    Maoz, D. & Graur, O. Star formation, supernovae, iron, and α: consistent cosmic and Galactic histories. Astrophys. J. 848, 25 (2017).

    ADS  Google Scholar 

  137. 137.

    Dominik, M. et al. Double compact objects. I. The significance of the common envelope on merger rates. Astrophys. J. 759, 52 (2012).

    ADS  Google Scholar 

  138. 138.

    Chruslinska, M., Belczynski, K., Klencki, J. & Benacquista, M. Double neutron stars: merger rates revisited. Mon. Not. R. Astron. Soc. 474, 2937–2958 (2018).

    ADS  CAS  Google Scholar 

  139. 139.

    Villar, V. A. et al. 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. Astrophys. J. 851, L21 (2017).

    ADS  Google Scholar 

  140. 140.

    Suda, T. et al. Stellar abundances for the Galactic Archeology (SAGA) Database – compilation of the characteristics of known extremely metal-poor stars. Publ. Astron. Soc. Jpn 60, 1159 (2008).

    ADS  CAS  Google Scholar 

  141. 141.

    Côté, B. et al. Neutron star mergers might not be the only source of r-process elements in the Milky Way. Preprint at (2018).

  142. 142.

    Fong, W. et al. Short GRB130603B: discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess. Astrophys. J. 780, 118 (2014).

    ADS  Google Scholar 

  143. 143.

    McMillan, P. J. Mass models of the Milky Way. Mon. Not. R. Astron. Soc. 414, 2446–2457 (2011).

    ADS  Google Scholar 

  144. 144.

    Colgate, S. A., Petschek, A. G. & Kriese, J. T. The luminosity of type I supernovae. Astrophys. J. 237, L81–L85 (1980).

    ADS  CAS  Google Scholar 

Download references


Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. Support for this work was provided by NASA through Einstein postdoctoral fellowships (award numbers PF6-170159 and PF7-180162) issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. B.D.M. acknowledges support from NASA, through the Astrophysics Theory Program (NNX16AB30G).

Reviewer information

Nature thanks Andrew MacFadyen and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information




D.M.S. designed and performed the numerical simulations and led the interpretation of their results, developed the toy model of collapsar fallback accretion and Galactic chemical evolution, and drafted initial versions of most sections of Methods. J.B. performed the radiative transfer calculations of the light curves of collapsar supernovae with r-process enrichment and led their interpretation and incorporation into Methods. B.D.M. helped with designing the numerical calculations and with their interpretation, developed the analytic model for 56Ni production, and wrote the initial draft of the main text and some sections of Methods.

Corresponding author

Correspondence to Daniel M. Siegel.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 MHD characteristics of simulations.

a, Simulation snapshot of the meridional plane for run 2, showing the rest-mass density (ρ; upper half; contours at 106, 107, 108, 109, 1010 g cm−3) and number of grid points per wavelength of the fastest-growing MRI mode (λMRIx; lower half) once the stationary state has been reached after 30 ms. Note that the MRI is well resolved. b, Space–time diagram of the y component of the magnetic field (By; colour scale at right) for run 2, radially averaged between 45 and 70 km from the rotation axis in the xz (meridional) plane, as a function of height z relative to the equatorial plane, and time, indicating a fully operational dynamo and a steady turbulent state of the disk after about 20−30 ms.

Extended Data Fig. 2 Numerical characteristics of simulations.

a, Resolution study showing the maximum magnetic field strength in the disk midplane for run 2 and additional runs with varying resolution (but otherwise identical), indicating that magnetic field amplification has converged for the fiducial run with finest grid spacing, Δx (see key). b, Comparison of the accretion rate of run 2 (‘B’ in key) to a run with much lower initial magnetic field (but otherwise identical; ‘low B’ in key), showing that angular momentum transport and viscous heating are set by MHD turbulence.

Extended Data Fig. 3 Black hole accretion rate.

Shown are the black hole accretion rates as a function of time for the three main runs (1, 2 and 3), which represent the state of a collapsar accretion flow at consecutively later times following the core collapse of the star (see Fig. 1).

Extended Data Fig. 4 Effective MHD viscosity of the collapsar accretion disk.

Shown are radial profiles of the effective α-viscosity parameter for run 1 at different times (see key) spanning 100 ms of evolution.

Extended Data Fig. 5 Nickel and helium production in the collapsar disk outflows.

Shown are estimated 56Ni (red) and 4He (blue) mass fractions based on equation (13) along with extracted mass fractions from run 3 (uncertainties in the accretion rate are defined as in Fig. 1), at accretion rates below the ignition threshold (equation (6)). The coloured bands correspond to estimates bracketing the distribution of expansion timescales between 5 and 30 ms.

Extended Data Fig. 6 r-process enrichment through neutron-star mergers (left) and collapsars (right).

Although collapsars are somewhat less frequent than mergers over cosmic time, their higher r-process yields (by a factor of about 30, if calibrated using the energetics of long versus short GRB jets) make them an important and probably dominant r-process site (equation (26)). See Methods for nomenclature.

Extended Data Fig. 7 Oxygen abundance and metallicity of Milky Way stars.

Oxygen abundances for high-signal-to-noise (>200) stars from the full APOGEE DR14 sample114 are plotted versus metallicity, with individual stars being colour-coded by their effective temperature (colour scale at right). Shown for comparison with dashed lines are the range of oxygen thresholds for GRB generation113, with the fraction fZ of stars below the threshold indicated. An order-unity fraction of stars in the Milky Way were formed at metallicities below the threshold needed for collapsar production.

Extended Data Fig. 8 Radioactive heating rate from the r-process and the nickel burned in the GRB supernova.

The specific radioactive heating rate of the 56Ni/56Co chain from the associated supernova (blue) exceeds that of r-process nuclei (red) for \(1{\rm{d}}{\rm{a}}{\rm{y}}\lesssim t\lesssim 600{\rm{d}}{\rm{a}}{\rm{y}}{\rm{s}}\). This makes it possible to conceal large quantities of r-process material from collapsars in the centre of long GRB supernovae until very late times, \(t\gtrsim 100{\rm{d}}{\rm{a}}{\rm{y}}{\rm{s}}\). The difference between the released (dashed lines) and deposited (solid lines) energy reflects energy lost to neutrinos, to incomplete deposition of γ-ray energy from 56Ni/56Co decay144, and to inefficient thermalization of r-process decay products (as previously calculated102). Figure adapted from previous work115.

Extended Data Fig. 9 Galactic chemical evolution.

Shown are comparisons of model predictions with observational data for magnesium and europium abundances in Milky Way stars from the SAGA database140 ( and europium abundances of Galactic disk stars132. For definitions of error bars we refer to the SAGA database140. Model predictions are shown for different minimum delay times (see keys) of type Ia supernovae with respect to star formation. a, Comparison for magnesium as a representative α-element. b, Comparison for europium as an r-process tracer, assuming both neutron-star mergers and collapsars (NS+Coll.) contribute to Galactic r-process nucleosynthesis. Note that the decreasing trend of [Eu/Fe] at high metallicity can be obtained. c, As b but assuming that only neutron-star mergers (NS only) contribute to Galactic r-process nucleosynthesis, showing that merger-only models cannot explain the [Eu/Fe] trend of stars in the Galactic disk.

Extended Data Fig. 10 Galactic chemical evolution with varying collapsar contribution to the r-process.

The figure shows a comparison of model predictions with observational data for europium abundances as in Extended Data Fig. 9 (light blue points with error bars refer to the SAGA dataset140 (, that is, stars in the Milky Way disk plus halo, while cyan points refer to disk stars only132), assuming a minimum type Ia supernova delay time of 400 Myr and varying the contribution of neutron-star mergers. For definitions of error bars we refer to the SAGA database140. The curves are labelled (see key) by the fraction of overall r-process material contributed to the Galaxy by collapsars at the time of formation of the Solar System. The neutron-star merger contribution is altered by renormalizing the neutron-star merger rates, tuning fNSRNS(z = 0) (compare equation (37)) by a factor between 0.3 and 100. The fiducial model in Extended Data Fig. 9 corresponds to the red curve. A dominant contribution to the total Galactic r-process from collapsars improves the evolution of r-process enrichment at high metallicity relative to merger-only models.

Supplementary information

Supplementary Table

Table listing the amount of collapsar disk wind ejecta during different accretion stages, computed for various presupernova models.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Siegel, D.M., Barnes, J. & Metzger, B.D. Collapsars as a major source of r-process elements. Nature 569, 241–244 (2019).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing