Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks

The remnant black hole–accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture ( r -process). A critical factor in determining the full r -process pattern in these environments is the neutron...

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Main Authors: Kelsey A. Lund, Payel Mukhopadhyay, Jonah M. Miller, G. C. McLaughlin
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
Subjects:
Online Access:https://doi.org/10.3847/2041-8213/add0a7
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author Kelsey A. Lund
Payel Mukhopadhyay
Jonah M. Miller
G. C. McLaughlin
author_facet Kelsey A. Lund
Payel Mukhopadhyay
Jonah M. Miller
G. C. McLaughlin
author_sort Kelsey A. Lund
collection DOAJ
description The remnant black hole–accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture ( r -process). A critical factor in determining the full r -process pattern in these environments is the neutron richness of the ejecta, which is strongly influenced by neutrino interactions. One key ingredient shaping these interactions is fast neutrino flavor conversions (FFCs), which arise due to angular crossings in neutrino distributions and occur on nanosecond timescales. We present the first three-dimensional in situ angle-dependent modeling of FFCs in postmerger disks, implemented within general relativistic magnetohydrodynamics with Monte Carlo neutrino transport. Our results reveal that, by suppressing electron neutrinos, FFCs more efficiently cool the disk and weaken the early thermally driven wind. Less releptonization due to electron neutrino absorption makes this cooler wind more neutron rich, producing a more robust r -process at higher latitudes of the outflow. This study underscores the necessity of incorporating FFCs in realistic simulations.
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spelling doaj-art-7199e5cae84046c3867f31a2d4d7d5552025-08-20T03:49:27ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019851L910.3847/2041-8213/add0a7Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger DisksKelsey A. Lund0https://orcid.org/0000-0003-0031-1397Payel Mukhopadhyay1https://orcid.org/0000-0002-3954-2005Jonah M. Miller2https://orcid.org/0000-0001-6432-7860G. C. McLaughlin3https://orcid.org/0000-0001-6811-6657Department of Physics, University of California , Berkeley, CA 94720, USA ; klund@berkeley.edu; Institute for Nuclear Theory, University of Washington , Seattle, WA 98195, USADepartment of Physics, University of California , Berkeley, CA 94720, USA ; klund@berkeley.eduMichigan SPARC, Los Alamos National Laboratory , Ann Arbor, MI 48109, USA; Computational Physics and Methods, Los Alamos National Laboratory , Los Alamos, NM 87545, USA; Center for Theoretical Astrophysics, Los Alamos National Laboratory , Los Alamos, NM 87545, USADepartment of Physics, North Carolina State University , Raleigh, NC 27695, USAThe remnant black hole–accretion disk system resulting from binary neutron star mergers has proven to be a promising site for synthesizing the heaviest elements via rapid neutron capture ( r -process). A critical factor in determining the full r -process pattern in these environments is the neutron richness of the ejecta, which is strongly influenced by neutrino interactions. One key ingredient shaping these interactions is fast neutrino flavor conversions (FFCs), which arise due to angular crossings in neutrino distributions and occur on nanosecond timescales. We present the first three-dimensional in situ angle-dependent modeling of FFCs in postmerger disks, implemented within general relativistic magnetohydrodynamics with Monte Carlo neutrino transport. Our results reveal that, by suppressing electron neutrinos, FFCs more efficiently cool the disk and weaken the early thermally driven wind. Less releptonization due to electron neutrino absorption makes this cooler wind more neutron rich, producing a more robust r -process at higher latitudes of the outflow. This study underscores the necessity of incorporating FFCs in realistic simulations.https://doi.org/10.3847/2041-8213/add0a7NucleosynthesisNeutrino oscillationsCompact objects
spellingShingle Kelsey A. Lund
Payel Mukhopadhyay
Jonah M. Miller
G. C. McLaughlin
Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
The Astrophysical Journal Letters
Nucleosynthesis
Neutrino oscillations
Compact objects
title Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
title_full Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
title_fullStr Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
title_full_unstemmed Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
title_short Angle-dependent in Situ Fast Flavor Transformations in Post-neutron-star-merger Disks
title_sort angle dependent in situ fast flavor transformations in post neutron star merger disks
topic Nucleosynthesis
Neutrino oscillations
Compact objects
url https://doi.org/10.3847/2041-8213/add0a7
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AT payelmukhopadhyay angledependentinsitufastflavortransformationsinpostneutronstarmergerdisks
AT jonahmmiller angledependentinsitufastflavortransformationsinpostneutronstarmergerdisks
AT gcmclaughlin angledependentinsitufastflavortransformationsinpostneutronstarmergerdisks