Mark Alford
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View article: Thermal and Magnetic effects on Bulk Viscosity in Binary Neutron Star Mergers
Thermal and Magnetic effects on Bulk Viscosity in Binary Neutron Star Mergers Open
Astrophysical scenarios such as binary neutron star mergers, proto-neutron stars and core-collapse supernovae involve finite temperatures and strong magnetic fields. Previous studies on the effect of magnetic fields on flavor-equilibration…
View article: Bulk viscosity of two-flavor color superconducting quark matter in neutron star mergers
Bulk viscosity of two-flavor color superconducting quark matter in neutron star mergers Open
This work investigates the bulk viscosity of warm, dense, neutrino-transparent, color-superconducting quark matter, where damping of density oscillations in the kHz frequency range arises from weak-interaction-driven direct Urca processes …
View article: Computational Notebooks for Building Neutron Stars with the MUSES Calculation Engine
Computational Notebooks for Building Neutron Stars with the MUSES Calculation Engine Open
This collection of three Jupyter notebooks contains MUSES workflows used to obtain the results presented in the paper Building Neutron Stars with the MUSES Calculation Engine [1]. The MUSES Calculation Engine is a web-based application and…
View article: Effect of Magnetic Fields on Urca Rates in Neutron Star Mergers
Effect of Magnetic Fields on Urca Rates in Neutron Star Mergers Open
Isospin-equilibrating weak processes, called ``Urca" processes, are of fundamental importance in astrophysical environments like (proto-)neutron stars, neutron star mergers, and supernovae. In these environments, matter can reach high temp…
View article: Bulk viscosity of two-color superconducting quark matter in neutron star mergers
Bulk viscosity of two-color superconducting quark matter in neutron star mergers Open
We study the bulk viscosity of moderately hot and dense, neutrino-transparent\ncolor superconducting quark matter arising from weak-interaction-driven direct\nURCA processes. The quark matter is modeled using the Nambu--Jona-Lasinio model\…
View article: Confronting new NICER mass-radius measurements with phase transition in dense matter and twin compact stars
Confronting new NICER mass-radius measurements with phase transition in dense matter and twin compact stars Open
The (re)analysis of data on the X-ray emitting pulsars PSR J0030+0451 and J0740+6620, as well as new results on PSR J0437-4715 and J1231-1411, are confronted with the predictions of the equation of state (EoS) models allowing for strong fi…
View article: Beyond modified Urca: the nucleon width approximation for flavor-changing processes in dense matter
Beyond modified Urca: the nucleon width approximation for flavor-changing processes in dense matter Open
Flavor-changing charged current ("Urca") processes are of central importance in the astrophysics of neutron stars. Standard calculations approximate the Urca rate as the sum of two contributions, direct Urca and modified Urca. Attempts to …
View article: Theoretical and experimental constraints for the equation of state of dense and hot matter
Theoretical and experimental constraints for the equation of state of dense and hot matter Open
This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effect…
View article: Hybrid Star Models in the Light of New Multimessenger Data
Hybrid Star Models in the Light of New Multimessenger Data Open
Recent astrophysical mass inferences of compact stars HESS J1731-347 and PSR J0952-0607, with extremely small and large masses respectively, as well as the measurement of the neutron skin of Ca in the CREX experiment challenge and constrai…
View article: Isospin equilibration in neutron star mergers
Isospin equilibration in neutron star mergers Open
We analyze the isospin equilibration properties of neutrinoless nuclear (npe) matter in the temperature and density range that is relevant to neutron star mergers. Our analysis incorporates neutrino-transparency corrections to the isospin …
View article: Emergence of Microphysical Bulk Viscosity in Binary Neutron Star Postmerger Dynamics
Emergence of Microphysical Bulk Viscosity in Binary Neutron Star Postmerger Dynamics Open
In nuclear matter in isolated neutron stars, the flavor content (e.g., proton fraction) is subject to weak interactions, establishing flavor ( β -)equilibrium. However, there can be deviations from this equilibrium during the merger of two…
View article: Hybrid star models in the light of new multi-messenger data
Hybrid star models in the light of new multi-messenger data Open
Recent astrophysical mass inferences of compact stars HESS J1731-347 and PSR J0952-0607, with extremely small and large masses respectively, as well as the measurement of the neutron skin of Ca in the CREX experiment challenge and constrai…
View article: Tabulated equations of state from models informed by chiral effective field theory
Tabulated equations of state from models informed by chiral effective field theory Open
We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a rela…
View article: Bulk viscosity from Urca processes: $npeμ$ matter in the neutrino-transparent regime
Bulk viscosity from Urca processes: $npeμ$ matter in the neutrino-transparent regime Open
We study the bulk viscosity of moderately hot and dense, neutrino-transparent relativistic $npeμ$ matter arising from weak-interaction direct Urca processes. This work parallels our recent study of the bulk viscosity of $npeμ$ matter with …
View article: Isospin Equilibration in Neutron Star Mergers
Isospin Equilibration in Neutron Star Mergers Open
We analyze the isospin equilibration properties of neutrinoless nuclear ($npe$) matter in the temperature and density range that is relevant to neutron star mergers. Our analysis incorporates neutrino-transparency corrections to the isospi…
View article: Tabulated Equations of State From Models Informed by Chiral Effective Field Theory
Tabulated Equations of State From Models Informed by Chiral Effective Field Theory Open
We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a rela…
View article: Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter
Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter Open
This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effect…
View article: Relativistic Hybrid Stars with Sequential First-order Phase Transitions in Light of Multimessenger Constraints
Relativistic Hybrid Stars with Sequential First-order Phase Transitions in Light of Multimessenger Constraints Open
In this work, we consider the properties of compact stars in which quark matter has low- and high-density phases that are separated by a first-order phase transition. Thus, unlike the commonly considered case of a single phase transition f…
View article: Relativistic hybrid stars with sequential first-order phase transitions in light of multimessenger constraints
Relativistic hybrid stars with sequential first-order phase transitions in light of multimessenger constraints Open
In this work, we consider the properties of compact stars in which quark matter has low- and high-density phases that are separated by a first-order phase transition. Thus, unlike the commonly considered case of a single phase transition f…
View article: Ultracompact hybrid stars consistent with multimessenger astrophysics
Ultracompact hybrid stars consistent with multimessenger astrophysics Open
In this work, we consider the consequences of phase transition in dense QCD on the properties of compact stars and implications for the observational program in gravitational wave and x-ray astrophysics. The key underlying assumption of ou…
View article: Relativistic mean-field theories for neutron-star physics based on chiral effective field theory
Relativistic mean-field theories for neutron-star physics based on chiral effective field theory Open
We describe and implement a procedure for determining the couplings of a relativistic mean-field theory (RMFT) that is optimized for application to neutron star phenomenology. In the standard RMFT approach, the couplings are constrained by…
View article: Long Range Plan: Dense matter theory for heavy-ion collisions and neutron stars
Long Range Plan: Dense matter theory for heavy-ion collisions and neutron stars Open
Since the release of the 2015 Long Range Plan in Nuclear Physics, major events have occurred that reshaped our understanding of quantum chromodynamics (QCD) and nuclear matter at large densities, in and out of equilibrium. The US nuclear c…
View article: Bulk Viscosity of Relativistic npeμ Matter in Neutron-Star Mergers
Bulk Viscosity of Relativistic npeμ Matter in Neutron-Star Mergers Open
We discuss the bulk viscosity of hot and dense npeμ matter arising from weak-interaction direct Urca processes. We consider two regimes of interest: (a) the neutrino-transparent regime with T≤Ttr (Ttr≃5÷10 MeV is the neutrino-trapping temp…
View article: Ultracompact hybrid stars consistent with multimessenger astrophysics
Ultracompact hybrid stars consistent with multimessenger astrophysics Open
In this work, we consider the consequences of phase transition in dense QCD on the properties of compact stars and implications for the observational program in gravitational wave and X-ray astrophysics. The key underlying assumption of ou…
View article: Emergence of microphysical bulk viscosity in binary neutron star post-merger dynamics
Emergence of microphysical bulk viscosity in binary neutron star post-merger dynamics Open
In nuclear matter in isolated neutron stars, the flavor content (e.g., proton fraction) is subject to weak interactions, establishing flavor ($β$-)equilibrium. However, there can be deviations from this equilibrium during the merger of two…
View article: Relativistic mean-field theories for neutron-star physics based on chiral effective field theory
Relativistic mean-field theories for neutron-star physics based on chiral effective field theory Open
We describe and implement a procedure for determining the couplings of a Relativistic Mean-Field Theory (RMFT) that is optimized for application to neutron star phenomenology. In the standard RMFT approach, the couplings are constrained by…
View article: Beta Equilibrium under Neutron Star Merger Conditions
Beta Equilibrium under Neutron Star Merger Conditions Open
We calculate the nonzero-temperature correction to the beta equilibrium condition in nuclear matter under neutron star merger conditions, in the temperature range 1mEv < T ≲ 5 mEv. We improve on previous work using a consistent description…
View article: Projecting the likely importance of weak-interaction-driven bulk viscosity in neutron star mergers
Projecting the likely importance of weak-interaction-driven bulk viscosity in neutron star mergers Open
In this work, we estimate how much bulk viscosity driven by Urca processes is likely to affect the gravitational wave signal of a neutron star coalescence. In the late inspiral, we show that bulk viscosity affects the binding energy at fou…
View article: Relativistic hybrid stars in light of the NICER PSR J0740+6620 radius measurement
Relativistic hybrid stars in light of the NICER PSR J0740+6620 radius measurement Open
We explore the implications of the recent radius determination of PSR J0740+6620 by the NICER experiment combined with the neutron skin measurement by the PREX-II experiment and the associated inference of the slope of symmetry energy, for…
View article: Bulk viscosity from Urca processes: $npe\mu$-neutrino-trapped matter
Bulk viscosity from Urca processes: $npe\mu$-neutrino-trapped matter Open
In this work, we extend our previous study of the bulk viscosity of hot and dense $npe$ matter induced by the Urca process in the neutrino trapped regime to $npe\mu$ matter by adding the muonic Urca processes as well as the purely leptonic…