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@ARTICLE{Shi:641500,
      author       = {Shi, Xin-Yue and Pohl, Martin and Schulreich, Michael M.},
      title        = {{A}cceleration and {T}ransport of the {U}nstable
                      {C}osmic-{R}ay {I}sotope $^{60}${F}e in {S}upernova-enriched
                      {E}nvironments},
      reportid     = {PUBDB-2025-05077, arXiv:2506.23564},
      year         = {2025},
      note         = {16 pages, 6 figures, accepted for publication in ApJ,
                      comments are welcome},
      abstract     = {The unstable isotope $^{60}$Fe, with a half-life of 2.6
                      million years, is produced primarily in supernova
                      explosions. The observed presence of $^{60}$Fe in cosmic
                      rays and its detection in deep-sea crusts and sediments
                      suggest two possible scenarios: either the direct
                      acceleration of $^{60}$Fe from supernova ejecta or its
                      enrichment in the circumstellar material surrounding
                      supernova progenitors, which indicates cosmic ray production
                      in clusters of supernovae. Focusing on the latter scenario,
                      we consider an environment shaped by successive supernova
                      explosions, reminiscent of the Local Bubble around the time
                      of the most recent supernova explosion. We independently
                      tracked the evolution of the $^{60}$Fe mass ratio within the
                      Local Bubble using passive scalars. To investigate the
                      spectra of protons and $^{60}$Fe, we explicitly modeled
                      cosmic-ray acceleration and transport at the remnant of the
                      last supernova by simultaneously solving the hydrodynamical
                      equations for the supernova outflow and the transport
                      equations for cosmic rays, scattering turbulence, and
                      large-scale magnetic field, using the time-dependent
                      acceleration code Radiation Acceleration Transport Parallel
                      Code. The main uncertainty in our prediction of the local
                      $^{60}$Fe flux at about pc = 1 GeV nuc$^{−1}$ is the
                      magnetic-field structure in the Local Bubble and the
                      cosmic-ray diffusion beyond the approximately 100 kyr of
                      evolution covered by our study. We found that if the
                      standard galactic propagation applies, the local $^{60}$Fe
                      flux would be around 3\% of that measured. If there is a
                      sustained reduction in the diffusion coefficient at and near
                      the Local Bubble, then the expected $^{60}$Fe flux could be
                      up to 30\% of that measured.},
      cin          = {$Z_THAT$},
      ddc          = {520},
      cid          = {$I:(DE-H253)Z_THAT-20210408$},
      pnm          = {613 - Matter and Radiation from the Universe (POF4-613)},
      pid          = {G:(DE-HGF)POF4-613},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)25},
      eprint       = {2506.23564},
      howpublished = {arXiv:2506.23564},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2506.23564;\%\%$},
      doi          = {10.3204/PUBDB-2025-05077},
      url          = {https://bib-pubdb1.desy.de/record/641500},
}