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dc.contributor.authorFontes, C J
dc.contributor.authorFryer, C L
dc.contributor.authorHungerford, A L
dc.contributor.authorWollaeger, R T
dc.contributor.authorKorobkin, O
dc.date.accessioned2020-09-03T19:15:07Z
dc.date.available2020-09-03T19:15:07Z
dc.date.issued2020-02-26
dc.identifier.citationC J Fontes, C L Fryer, A L Hungerford, R T Wollaeger, O Korobkin, A line-binned treatment of opacities for the spectra and light curves from neutron star mergers, Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 3, April 2020, Pages 4143–4171, https://doi.org/10.1093/mnras/staa485en_US
dc.identifier.issn0035-8711
dc.identifier.doi10.1093/mnras/staa485
dc.identifier.urihttp://hdl.handle.net/10150/642375
dc.description.abstractThe electromagnetic observations of GW170817 were able to dramatically increase our understanding of neutron star mergers beyond what we learned from gravitational waves alone. These observations provided insight on all aspects of the merger from the nature of the gamma-ray burst to the characteristics of the ejected material. The ejecta of neutron star mergers are expected to produce such electromagnetic transients, called kilonovae or macronovae. Characteristics of the ejecta include large velocity gradients, relative to supernovae, and the presence of heavy r-process elements, which pose significant challenges to the accurate calculation of radiative opacities and radiation transport. For example, these opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. Here we investigate the use of fine-structure, line-binned opacities that preserve the integral of the opacity over frequency. Advantages of this area-preserving approach over the traditional expansion-opacity formalism include the ability to pre-calculate opacity tables that are independent of the type of hydrodynamic expansion and thus eliminate the computational expense of calculating opacities within radiation-transport simulations. Tabular opacities are generated for all 14 lanthanides as well as a representative actinide element, uranium. We demonstrate that spectral simulations produced with the line-binned opacities agree well with results produced with the more accurate continuous Monte Carlo Sobolev approach, as well as with the commonly used expansion-opacity formalism. The agreement between the line-binned and expansion-opacity results is explained as arising from the similarity in their opacities in the limit of low optical depth, where radiation transport is important in the ejecta. Additional investigations illustrate the convergence of opacity with respect to the number of included lines, and elucidate sensitivities to different atomic physics approximations, such as fully and semirelativistic approaches.en_US
dc.language.isoenen_US
dc.publisherOXFORD UNIV PRESSen_US
dc.rightsCopyright © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.en_US
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectgravitational wavesen_US
dc.subjectopacityen_US
dc.subjectradiative transferen_US
dc.subjectstars: neutronen_US
dc.titleA line-binned treatment of opacities for the spectra and light curves from neutron star mergersen_US
dc.typeArticleen_US
dc.contributor.departmentUniv Arizona, Phys Depten_US
dc.identifier.journalMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETYen_US
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en_US
dc.eprint.versionFinal published versionen_US
dc.source.journaltitleMonthly Notices of the Royal Astronomical Society
dc.source.volume493
dc.source.issue3
dc.source.beginpage4143
dc.source.endpage4171
refterms.dateFOA2020-09-03T19:15:23Z


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