English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The existence of 2 Msun pulsars puts very strong constraints on the equationof state (EOS) of neutron stars (NSs) with hyperon cores, which can besatisfied only by special models of hadronic matter. The radius-mass relationfor these models is sufficiently specific that it could be subjected to anobservational test with future X-ray observatories. We want to study the impactof the presence of hyperon cores on the radius-mass relation for NS. We aim tofind out how, and for which particular stellar mass range, a specific relationR(M), where M is the gravitational mass, and R is the circumferential radius,is associated with the presence of a hyperon core.  We consider a set of 14 theoretical EOS of dense matter, based on therelativistic mean-field (RMF) approximation, allowing for the presence ofhyperons in NSs. We seek correlations between R(M) and the stiffness of the EOSbelow the hyperon threshold needed to pass the 2 Msun test. For NS masses1.0<M/Msun<1.6, we get R>13km, because of a very stiff pre-hyperon segment ofthe EOS. At nuclear density, the pressure is significantly higher than a robustupper bound obtained recently using chiral effective field theory.  If massive NSs do have a sizable hyperon core, then according to currentmodels the radii for M=1.0-1.6 Msun are necessarily >13km. If, on the contrary,a NS with a radius R<12 km is observed in this mass domain, then sizablehyperon cores in NSs, as we model them now, are ruled out. Future X-raymissions with <5% precision for a simultaneous M and R measurement will havethe potential to solve the problem with observations of NSs. Irrespective ofthis observational test, present EOS allowing for hyperons that fulfillcondition M_max>2 Msun yield a pressure at nuclear density that is too highrelative to up-to-date microscopic calculations of this quantity.

Neutron stars with hyperon cores: stellar radii and EOS near nuclear density