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@ARTICLE{RodgersLee:602149,
      author       = {Rodgers-Lee, D. and Rimmer, P. B. and Vidotto, A. A. and
                      Louca, A. J. and Taylor, Andrew and Mesquita, A. L. and
                      Miguel, Y. and Venot, O. and Helling, C. and Barth, P. and
                      Lacy, E.},
      title        = {{T}he energetic particle environment of a {GJ} 436 b-like
                      planet},
      reportid     = {PUBDB-2024-00490, arXiv:2303.07058},
      year         = {2023},
      note         = {14 pages, 9 figures, accepted for publication in MNRAS},
      abstract     = {A key first step to constrain the impact of energetic
                      particles in exoplanet atmospheres is to detect the chemical
                      signature of ionisation due to stellar energetic particles
                      and Galactic cosmic rays. We focus on GJ$\,$436, a
                      well-studied M dwarf with a warm Neptune-like exoplanet. We
                      demonstrate how the maximum stellar energetic particle
                      momentum can be estimated from the stellar X-ray luminosity.
                      We model energetic particle transport through the atmosphere
                      of a hypothetical exoplanet at orbital distances between
                      $a=0.01-0.2\,$au from GJ$\,$436, including GJ$\,$436$\,$b's
                      orbital distance (0.028$\,$au). For these distances we find
                      that, at top-of-atmosphere, stellar energetic particles
                      ionise molecular hydrogen at a rate of $\zeta_{\rm StEP,H_2}
                      \sim 4\times10^{-10}-2\times10^{-13}\,\mathrm{s^{-1}}$. In
                      comparison, Galactic cosmic rays alone lead to $\zeta_{\rm
                      GCR, H_2}\sim2\times 10^{-20}-10^{-18} \,\mathrm{s^{-1}}$.
                      At 10au we find that ionisation due to Galactic cosmic rays
                      equals that of stellar energetic particles: $\zeta_{\rm
                      GCR,H_2} = \zeta_{\rm StEP,H_2} \sim
                      7\times10^{-18}\,\rm{s^{-1}}$ for the top-of-atmosphere
                      ionisation rate. At GJ$\,$436$\,$b's orbital distance, the
                      maximum ion-pair production rate due to stellar energetic
                      particles occurs at pressure $P\sim 10^{-3}\,$bar while
                      Galactic cosmic rays dominate for $P>10^2\,$bar. These high
                      pressures are similar to what is expected for a post-impact
                      early Earth atmosphere. The results presented here will be
                      used to quantify the chemical signatures of energetic
                      particles in warm Neptune-like atmospheres.},
      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       = {2303.07058},
      howpublished = {arXiv:2303.07058},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2303.07058;\%\%$},
      doi          = {10.3204/PUBDB-2024-00490},
      url          = {https://bib-pubdb1.desy.de/record/602149},
}