Publications
NEUTRONSTARS CoE started operating in 2026. Since the starting date, … papers have been published.
6549793
1
apa
50
default
1
217
https://neutronstars.fi/wp-content/plugins/zotpress/
%7B%22status%22%3A%22success%22%2C%22updateneeded%22%3Afalse%2C%22instance%22%3Afalse%2C%22meta%22%3A%7B%22request_last%22%3A0%2C%22request_next%22%3A0%2C%22used_cache%22%3Atrue%7D%2C%22data%22%3A%5B%7B%22key%22%3A%22U5IJPN65%22%2C%22library%22%3A%7B%22id%22%3A6549793%7D%2C%22meta%22%3A%7B%22creatorSummary%22%3A%22Dorsman%20et%20al.%22%2C%22parsedDate%22%3A%222026-01%22%2C%22numChildren%22%3A1%7D%2C%22bib%22%3A%22%26lt%3Bdiv%20class%3D%26quot%3Bcsl-bib-body%26quot%3B%20style%3D%26quot%3Bline-height%3A%202%3B%20padding-left%3A%201em%3B%20text-indent%3A-1em%3B%26quot%3B%26gt%3B%5Cn%20%20%26lt%3Bdiv%20class%3D%26quot%3Bcsl-entry%26quot%3B%26gt%3BDorsman%2C%20B.%2C%20Salmi%2C%20T.%2C%20Watts%2C%20A.%20L.%2C%20Ng%2C%20M.%2C%20Bobrikova%2C%20A.%2C%20Loktev%2C%20V.%2C%20Poutanen%2C%20J.%2C%20%26amp%3B%20Wilms%2C%20J.%20%282026%29.%20Pulse%20profile%20modelling%20of%20the%20accretion-powered%20millisecond%20pulsar%20SAX%20J1808.4%26%23×2212%3B3658%20using%20NICER%20data%20from%20its%202019%20and%202022%20outbursts.%20%26lt%3Bi%26gt%3BMonthly%20Notices%20of%20the%20Royal%20Astronomical%20Society%2C%20Volume%20545%2C%20Issue%202%26lt%3B%5C%2Fi%26gt%3B%2C%20%26lt%3Bi%26gt%3B545%26lt%3B%5C%2Fi%26gt%3B%282%29%2C%20staf1983.%20%26lt%3Ba%20class%3D%26%23039%3Bzp-DOIURL%26%23039%3B%20href%3D%26%23039%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.1093%5C%2Fmnras%5C%2Fstaf1983%26%23039%3B%26gt%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.1093%5C%2Fmnras%5C%2Fstaf1983%26lt%3B%5C%2Fa%26gt%3B%26lt%3B%5C%2Fdiv%26gt%3B%5Cn%26lt%3B%5C%2Fdiv%26gt%3B%22%2C%22data%22%3A%7B%22itemType%22%3A%22journalArticle%22%2C%22title%22%3A%22Pulse%20profile%20modelling%20of%20the%20accretion-powered%20millisecond%20pulsar%20SAX%20J1808.4%5Cu22123658%20using%20NICER%20data%20from%20its%202019%20and%202022%20outbursts%22%2C%22creators%22%3A%5B%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Bas%22%2C%22lastName%22%3A%22Dorsman%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Tuomo%22%2C%22lastName%22%3A%22Salmi%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Anna%20L.%22%2C%22lastName%22%3A%22Watts%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Mason%22%2C%22lastName%22%3A%22Ng%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Anna%22%2C%22lastName%22%3A%22Bobrikova%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Vladislav%22%2C%22lastName%22%3A%22Loktev%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Juri%22%2C%22lastName%22%3A%22Poutanen%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Joern%22%2C%22lastName%22%3A%22Wilms%22%7D%5D%2C%22abstractNote%22%3A%22Pulse%20profile%20modelling%20is%20a%20relativistic%20ray-tracing%20technique%20that%20has%20provided%20constraints%20on%20parameters%2C%20with%20a%20focus%20on%20mass%20and%20radius%2C%20of%20five%20rotation-powered%20millisecond%20pulsars.%20While%20the%20technique%20can%20also%20be%20applied%20to%20accretion-powered%20millisecond%20pulsars%20%28AMPs%29%2C%20this%20requires%20accounting%20for%20the%20X-rays%20from%20the%20accretion%20disc%20and%20has%20only%20been%20applied%20to%20archival%20data%20from%20the%20Rossi%20X-ray%20Timing%20Explorer.%20Here%2C%20we%20apply%20a%20previously%20developed%20neutron%20star%20and%20accretion%20disc%20model%20to%20the%20NICER%20%28Neutron%20star%20Interior%20Composition%20Explorer%29%20data%20of%20the%202019%20and%202022%20outbursts%20of%20SAX%20J1808.4%5Cu25003658.%20We%20find%20that%20a%20single%20circular%20hotspot%20model%20is%20insufficient%20to%20explain%20the%20data.%20Modelling%20with%20two%20hotspots%20and%20an%20accretion%20disc%20model%20provides%20better%20phase-residuals%2C%20but%20a%20spectral%20residual%20at%20around%201%20keV%20remains.%20In%20contrast%2C%20we%20find%20a%20good%20fit%20with%20a%20flexible%20background%20approach%2C%20replacing%20the%20accretion%20disc.%20However%2C%20the%20inferred%20parameters%20are%20not%20robust%20due%20to%20a%20degeneracy%20in%20the%20origin%20of%20the%20non-pulsed%20radiation%2C%20which%20can%20be%20caused%20either%20by%20the%20background%20or%20a%20hotspot%20that%20is%20at%20least%20partially%20in%20view%20throughout%20a%20full%20rotation.%20This%20work%20represents%20an%20important%20next%20step%20in%20pulse%20profile%20modelling%20of%20AMPs%20by%20analysing%20NICER%20data%20and%20underlines%20the%20need%20for%20more%20accurate%20accretion%20disc%20and%20hotspot%20modelling%20to%20achieve%20robust%20parameter%20constraints.%20We%20expect%20the%20inclusion%20of%20higher%20energy%20and%20polarimetric%20data%20will%20provide%20complementary%20constraints%20on%20inclination%2C%20hotspot%20colatitude%2C%20and%20hotspot%20size%2C%20improving%20the%20accuracy%20of%20pulse%20profile%20modelling%20of%20AMPs.%22%2C%22date%22%3A%222026-01-00%22%2C%22section%22%3A%22%22%2C%22partNumber%22%3A%22%22%2C%22partTitle%22%3A%22%22%2C%22DOI%22%3A%2210.1093%5C%2Fmnras%5C%2Fstaf1983%22%2C%22citationKey%22%3A%22%22%2C%22url%22%3A%22https%3A%5C%2F%5C%2Fui.adsabs.harvard.edu%5C%2Fabs%5C%2F2026MNRAS.545f1983D%5C%2Fabstract%22%2C%22PMID%22%3A%22%22%2C%22PMCID%22%3A%22%22%2C%22ISSN%22%3A%220035-8711%22%2C%22language%22%3A%22en%22%2C%22collections%22%3A%5B%5D%2C%22dateModified%22%3A%222026-05-12T10%3A22%3A15Z%22%7D%7D%2C%7B%22key%22%3A%22II8SJAKD%22%2C%22library%22%3A%7B%22id%22%3A6549793%7D%2C%22meta%22%3A%7B%22creatorSummary%22%3A%22Suleimanov%20et%20al.%22%2C%22parsedDate%22%3A%222026-04%22%2C%22numChildren%22%3A1%7D%2C%22bib%22%3A%22%26lt%3Bdiv%20class%3D%26quot%3Bcsl-bib-body%26quot%3B%20style%3D%26quot%3Bline-height%3A%202%3B%20padding-left%3A%201em%3B%20text-indent%3A-1em%3B%26quot%3B%26gt%3B%5Cn%20%20%26lt%3Bdiv%20class%3D%26quot%3Bcsl-entry%26quot%3B%26gt%3BSuleimanov%2C%20V.%20F.%2C%20Poutanen%2C%20J.%2C%20%26amp%3B%20Werner%2C%20K.%20%282026%29.%20Neutron%20star%20atmospheres%20composed%20of%20fusion%20ashes.%20%26lt%3Bi%26gt%3BarXiv.2604.16650%26lt%3B%5C%2Fi%26gt%3B.%20%26lt%3Ba%20class%3D%26%23039%3Bzp-DOIURL%26%23039%3B%20href%3D%26%23039%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2604.16650%26%23039%3B%26gt%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2604.16650%26lt%3B%5C%2Fa%26gt%3B%26lt%3B%5C%2Fdiv%26gt%3B%5Cn%26lt%3B%5C%2Fdiv%26gt%3B%22%2C%22data%22%3A%7B%22itemType%22%3A%22journalArticle%22%2C%22title%22%3A%22Neutron%20star%20atmospheres%20composed%20of%20fusion%20ashes%22%2C%22creators%22%3A%5B%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Valery%20F.%22%2C%22lastName%22%3A%22Suleimanov%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Juri%22%2C%22lastName%22%3A%22Poutanen%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Klaus%22%2C%22lastName%22%3A%22Werner%22%7D%5D%2C%22abstractNote%22%3A%22Here%20we%20present%20models%20of%20hot%20neutron%20star%20%28NS%29%20atmospheres%20consisting%20of%20thermonuclear%20ashes%20of%20various%20chemical%20compositions.%20These%20models%20are%20essential%20for%20studying%20thermonuclear%20flashes%20in%20X-ray%20bursting%20NSs%20in%20which%20nuclear-burning%20ashes%20are%20transported%20to%20the%20stellar%20surface.%20We%20consider%20four%20different%20mixtures%2C%20each%20dominated%20by%20helium%2C%20chromium%2C%20iron%2C%20or%20nickel.%20In%20addition%20to%20the%20opacity%20sources%20previously%20used%20in%20NS%20atmosphere%20modeling%2C%20we%20include%20photoionization%20from%20excited%20ionic%20states%20as%20well%20as%20approximately%205000%20spectral%20lines.%20We%20also%20develop%20a%20method%20that%20enables%20the%20simultaneous%20treatment%20of%20Compton%20scattering%20and%20a%20large%20number%20of%20spectral%20lines.%20A%20key%20feature%20of%20the%20modeled%20NS%20atmospheres%20is%20the%20presence%20of%20a%20layer%20in%20the%20transition%20region%20between%20the%20optically%20thin%20and%20optically%20thick%20parts%20of%20the%20atmosphere%20where%20the%20radiation-pressure%20force%20increases%20significantly.%20This%20enhanced%20force%20sets%20an%20upper%20limit%20on%20the%20maximum%20attainable%20bolometric%20flux%20for%20a%20given%20surface%20gravity%20and%20chemical%20composition.%20The%20emergent%20spectra%20from%20the%20computed%20atmospheres%20display%20pronounced%20absorption%20edges%2C%20whose%20energies%20are%20determined%20by%20the%20dominant%20chemical%20species.%20We%20fit%20the%20model%20spectra%20using%20a%20diluted%20blackbody%20modified%20by%20a%20single%20absorption%20edge%2C%20and%20we%20investigate%20how%20the%20fit%20parameters%20depend%20on%20both%20the%20relative%20bolometric%20flux%20and%20the%20chemical%20composition%20of%20the%20atmosphere.%20Finally%2C%20we%20discuss%20constraints%20on%20these%20models%20imposed%20by%20the%20properties%20of%20X-ray%20bursts%20that%20exhibit%20absorption%20edges%20in%20their%20spectra%2C%20as%20observed%20in%20the%20systems%20HETE~J1900.1%24-%242455%20and%20GRS~1747%24-%24312.%22%2C%22date%22%3A%222026-04-00%22%2C%22section%22%3A%22%22%2C%22partNumber%22%3A%22%22%2C%22partTitle%22%3A%22%22%2C%22DOI%22%3A%2210.48550%5C%2FarXiv.2604.16650%22%2C%22citationKey%22%3A%22%22%2C%22url%22%3A%22https%3A%5C%2F%5C%2Fui.adsabs.harvard.edu%5C%2Fabs%5C%2F2026arXiv260416650S%5C%2Fabstract%22%2C%22PMID%22%3A%22%22%2C%22PMCID%22%3A%22%22%2C%22ISSN%22%3A%22%22%2C%22language%22%3A%22en%22%2C%22collections%22%3A%5B%5D%2C%22dateModified%22%3A%222026-05-12T10%3A21%3A57Z%22%7D%7D%2C%7B%22key%22%3A%22A5CC9JU3%22%2C%22library%22%3A%7B%22id%22%3A6549793%7D%2C%22meta%22%3A%7B%22creatorSummary%22%3A%22Kiuru%22%2C%22parsedDate%22%3A%222026-03%22%2C%22numChildren%22%3A1%7D%2C%22bib%22%3A%22%26lt%3Bdiv%20class%3D%26quot%3Bcsl-bib-body%26quot%3B%20style%3D%26quot%3Bline-height%3A%202%3B%20padding-left%3A%201em%3B%20text-indent%3A-1em%3B%26quot%3B%26gt%3B%5Cn%20%20%26lt%3Bdiv%20class%3D%26quot%3Bcsl-entry%26quot%3B%26gt%3BKiuru%2C%20O.%20%282026%29.%20Evaluation%20of%20QED%20cross%20sections%20in%20strong%20magnetic%20fields.%20%26lt%3Bi%26gt%3BarXiv.2603.26545%26lt%3B%5C%2Fi%26gt%3B.%20%26lt%3Ba%20class%3D%26%23039%3Bzp-DOIURL%26%23039%3B%20href%3D%26%23039%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2603.26545%26%23039%3B%26gt%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2603.26545%26lt%3B%5C%2Fa%26gt%3B%26lt%3B%5C%2Fdiv%26gt%3B%5Cn%26lt%3B%5C%2Fdiv%26gt%3B%22%2C%22data%22%3A%7B%22itemType%22%3A%22journalArticle%22%2C%22title%22%3A%22Evaluation%20of%20QED%20cross%20sections%20in%20strong%20magnetic%20fields%22%2C%22creators%22%3A%5B%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Olavi%22%2C%22lastName%22%3A%22Kiuru%22%7D%5D%2C%22abstractNote%22%3A%22Quantum%20electrodynamics%20%28QED%29%20becomes%20nonlinear%20when%20the%20magnetic%20field%20strength%20surpasses%20the%20critical%20Schwinger%20limit%20%24B_Q%20%5C%5Capprox%204.41%5C%5Ccdot%2010%5E%7B13%7D%24%20G.%20This%20limit%20is%20surpassed%2C%20for%20example%2C%20in%20the%20magnetospheres%20of%20a%20specific%20class%20of%20neutron%20stars%20known%20as%20magnetars%2C%20which%20has%20important%20consequences%20for%20magnetospheric%20plasma%20dynamics%20due%20to%20modifications%20in%20scattering%20cross%20sections.%20Using%20a%20formalism%20previously%20applied%20to%20the%20study%20of%20magnetic%20catalysis%2C%20I%20calculate%20the%20cross%20sections%20of%20all%20tree-level%201-to-2%2C%202-to-1%2C%20and%202-to-2%20particle%20QED%20scattering%20processes%20that%20do%20not%20include%20a%20photon%20propagator.%20The%20calculations%20are%20done%20in%20a%20strong%20background%20magnetic%20field%20and%20the%20results%20are%20implemented%20into%20an%20open-source%20Python%20package.%20This%20article%20focuses%20on%20presenting%20the%20formalism%20and%20computational%20techniques%20required%20for%20the%20calculations%2C%20while%20the%20impact%20of%20the%20results%20on%2C%20e.g.%2C%20magnetospheric%20plasma%20dynamics%20is%20discussed%20in%20a%20companion%20letter%20%28Kiuru%20et%20al.%202026%29.%22%2C%22date%22%3A%222026-03-00%22%2C%22section%22%3A%22%22%2C%22partNumber%22%3A%22%22%2C%22partTitle%22%3A%22%22%2C%22DOI%22%3A%2210.48550%5C%2FarXiv.2603.26545%22%2C%22citationKey%22%3A%22%22%2C%22url%22%3A%22https%3A%5C%2F%5C%2Fui.adsabs.harvard.edu%5C%2Fabs%5C%2F2026arXiv260326545K%5C%2Fabstract%22%2C%22PMID%22%3A%22%22%2C%22PMCID%22%3A%22%22%2C%22ISSN%22%3A%22%22%2C%22language%22%3A%22en%22%2C%22collections%22%3A%5B%5D%2C%22dateModified%22%3A%222026-05-12T10%3A21%3A48Z%22%7D%7D%2C%7B%22key%22%3A%22TVXNL4CV%22%2C%22library%22%3A%7B%22id%22%3A6549793%7D%2C%22meta%22%3A%7B%22creatorSummary%22%3A%22Kiuru%20et%20al.%22%2C%22parsedDate%22%3A%222026-03%22%2C%22numChildren%22%3A1%7D%2C%22bib%22%3A%22%26lt%3Bdiv%20class%3D%26quot%3Bcsl-bib-body%26quot%3B%20style%3D%26quot%3Bline-height%3A%202%3B%20padding-left%3A%201em%3B%20text-indent%3A-1em%3B%26quot%3B%26gt%3B%5Cn%20%20%26lt%3Bdiv%20class%3D%26quot%3Bcsl-entry%26quot%3B%26gt%3BKiuru%2C%20O.%2C%20N%26%23xE4%3Bttil%26%23xE4%3B%2C%20J.%2C%20Paatelainen%2C%20R.%2C%20%26amp%3B%20Vuorinen%2C%20A.%20%282026%29.%20QED%20cross%20sections%20in%20strong%20magnetic%20fields.%20%26lt%3Bi%26gt%3BarXiv.2603.25491%26lt%3B%5C%2Fi%26gt%3B.%20%26lt%3Ba%20class%3D%26%23039%3Bzp-DOIURL%26%23039%3B%20href%3D%26%23039%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2603.25491%26%23039%3B%26gt%3Bhttps%3A%5C%2F%5C%2Fdoi.org%5C%2F10.48550%5C%2FarXiv.2603.25491%26lt%3B%5C%2Fa%26gt%3B%26lt%3B%5C%2Fdiv%26gt%3B%5Cn%26lt%3B%5C%2Fdiv%26gt%3B%22%2C%22data%22%3A%7B%22itemType%22%3A%22journalArticle%22%2C%22title%22%3A%22QED%20cross%20sections%20in%20strong%20magnetic%20fields%22%2C%22creators%22%3A%5B%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Olavi%22%2C%22lastName%22%3A%22Kiuru%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Joonas%22%2C%22lastName%22%3A%22N%5Cu00e4ttil%5Cu00e4%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Risto%22%2C%22lastName%22%3A%22Paatelainen%22%7D%2C%7B%22creatorType%22%3A%22author%22%2C%22firstName%22%3A%22Aleksi%22%2C%22lastName%22%3A%22Vuorinen%22%7D%5D%2C%22abstractNote%22%3A%22The%20magnetospheres%20of%20magnetars%2C%20a%20class%20of%20highly%20magnetized%20neutron%20stars%2C%20host%20magnetic%20fields%20exceeding%20the%20Schwinger%20limit%2C%20where%20Quantum%20Electrodynamics%20%28QED%29%20becomes%20nonlinear.%20In%20such%20environments%2C%20QED%20scattering%20processes%20are%20strongly%20modified%2C%20which%20may%20affect%20plasma%20dynamics.%20In%20this%20work%2C%20we%20apply%20a%20formalism%20originally%20developed%20for%20the%20study%20of%20magnetic-field%20effects%20in%20hot%20quark-gluon%20plasma%20to%20strong-field%20QED.%20The%20method%20resums%20interactions%20between%20virtual%20electrons%20and%20the%20external%20magnetic%20field%2C%20consistently%20incorporating%20the%20finite%20decay%20widths%20of%20excited%20Landau%20levels%20derived%20from%20the%20fermion%20self-energy.%20Using%20this%20framework%2C%20we%20perform%20the%20first%20systematic%20analysis%20of%20tree-level%20QED%20scattering%20processes%20in%20strong%20magnetic%20fields%2C%20concentrating%20on%20the%20processes%20of%20highest%20relevance%20for%20the%20plasma%20dynamics%20of%20magnetars.%20All%20resulting%20cross%20sections%20are%20provided%20in%20an%20open-source%20Python%20package.%22%2C%22date%22%3A%222026-03-00%22%2C%22section%22%3A%22%22%2C%22partNumber%22%3A%22%22%2C%22partTitle%22%3A%22%22%2C%22DOI%22%3A%2210.48550%5C%2FarXiv.2603.25491%22%2C%22citationKey%22%3A%22%22%2C%22url%22%3A%22https%3A%5C%2F%5C%2Fui.adsabs.harvard.edu%5C%2Fabs%5C%2F2026arXiv260325491K%5C%2Fabstract%22%2C%22PMID%22%3A%22%22%2C%22PMCID%22%3A%22%22%2C%22ISSN%22%3A%22%22%2C%22language%22%3A%22en%22%2C%22collections%22%3A%5B%5D%2C%22dateModified%22%3A%222026-05-12T10%3A21%3A40Z%22%7D%7D%5D%7D
Dorsman, B., Salmi, T., Watts, A. L., Ng, M., Bobrikova, A., Loktev, V., Poutanen, J., & Wilms, J. (2026). Pulse profile modelling of the accretion-powered millisecond pulsar SAX J1808.4−3658 using NICER data from its 2019 and 2022 outbursts. Monthly Notices of the Royal Astronomical Society, Volume 545, Issue 2, 545(2), staf1983. https://doi.org/10.1093/mnras/staf1983
Suleimanov, V. F., Poutanen, J., & Werner, K. (2026). Neutron star atmospheres composed of fusion ashes. arXiv.2604.16650. https://doi.org/10.48550/arXiv.2604.16650
Kiuru, O. (2026). Evaluation of QED cross sections in strong magnetic fields. arXiv.2603.26545. https://doi.org/10.48550/arXiv.2603.26545
Kiuru, O., Nättilä, J., Paatelainen, R., & Vuorinen, A. (2026). QED cross sections in strong magnetic fields. arXiv.2603.25491. https://doi.org/10.48550/arXiv.2603.25491