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Precise measurements of neutron star masses and radii by the NICER mission impose important constraints on the nuclear equation of state. The most recent NICER measurement of PSR J0614-3329 reported an equatorial radius of $R_{eq} =…

High Energy Astrophysical Phenomena · Physics 2025-12-05 Swarnim Shirke , Rajesh Maiti , Debarati Chatterjee

As an update to our previously performed Bayesian inference analyses of the neutron star matter equation-of-state and related quantities, the additional impact of the recently published NICER data of PSR J0437-4751 is examined. Including…

Nuclear Theory · Physics 2025-03-11 Len Brandes , Wolfram Weise

Understanding the dense matter equation of state at extreme conditions is an important open problem. Astrophysical observations of neutron stars promise to solve this, with NICER poised to make precision measurements of mass and radius for…

High Energy Astrophysical Phenomena · Physics 2019-03-20 S. K. Greif , G. Raaijmakers , K. Hebeler , A. Schwenk , A. L. Watts

The past years have witnessed tremendous progress in understanding the properties of neutron stars and of the dense matter in their cores, made possible by electromagnetic observations of neutron stars and the detection of gravitational…

A pure nucleonic equation of state (EoS) for beta equilibrated charge neutral neutron star (NS) matter is determined using density dependent effective NN interaction. This EoS is found to satisfy both the constraints from the observed…

Nuclear Theory · Physics 2011-05-11 Partha Roy Chowdhury

I summarize some constraints on the physics of neutron stars arising from X-ray observations of the surfaces of neutron stars, focusing on using models of low-magnetic-field neutron star atmospheres to interpret their X-ray spectra. I…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Craig O. Heinke

The cooling phase of thermonuclear (type-I) X-ray bursts can be used to constrain the neutron star (NS) compactness by comparing the observed cooling tracks of bursts to accurate theoretical atmosphere model calculations. By applying the…

High Energy Astrophysical Phenomena · Physics 2016-06-08 J. Nättilä , A. W. Steiner , J. J. E. Kajava , V. F. Suleimanov , J. Poutanen

Through continuous progress in nuclear theory and experiment and an increasing number of neutron-star observations, a multitude of information about the equation of state (EOS) for matter at extreme densities is available. To constrain the…

Neutron star matter spans a wide range of densities, from that of nuclei at the surface to exceeding several times normal nuclear matter density in the core. While terrestrial experiments, such as nuclear or heavy-ion collision experiments,…

High Energy Astrophysical Phenomena · Physics 2023-12-19 Suprovo Ghosh , Debarati Chatterjee , Jürgen Schaffner-Bielich

Observations of neutron stars, whether in binaries or in isolation, provide information about the internal structure of the most extreme material objects in the Universe. In this work, we combine information from recent observations to…

High Energy Astrophysical Phenomena · Physics 2021-08-29 Philippe Landry , Reed Essick , Katerina Chatziioannou

Few unified equations of state for neutron star matter where core and crust are described using the same nuclear model are available. However the use of non-unified equations of state with a simplified matching between the crust and the…

High Energy Astrophysical Phenomena · Physics 2016-11-07 J. L. Zdunik , M. Fortin , P. Haensel

Observations of thermonuclear X-ray bursts from accreting neutron stars (NSs) in low-mass X-ray binary systems can be used to constrain NS masses and radii. Most previous work of this type has set these constraints using Planck function…

High Energy Astrophysical Phenomena · Physics 2017-12-06 J. Nättilä , M. C. Miller , A. W. Steiner , J. J. E. Kajava , V. F. Suleimanov , J. Poutanen

We analyzed the thermal emission from the entire surface of the millisecond pulsar PSR J0437-4715 observed in the ultraviolet and soft X-ray bands. For this, we calculated non-magnetized, partially ionized atmosphere models of hydrogen,…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Denis Gonzalez-Caniulef , Sebastien Guillot , Andreas Reisenegger

We present a model of thermal X-ray emission from hot spots on the surface of a rotating compact star with an unmagnetized light-element atmosphere. An application to ROSAT, Chandra, and XMM-Newton X-ray observations of the nearest known…

Astrophysics · Physics 2009-11-11 Slavko Bogdanov , George B. Rybicki , Jonathan E. Grindlay

Exploiting a very large library of physically plausible equations of state (EOSs) containing more than $10^{7}$ members and yielding more than $10^{9}$ stellar models, we conduct a survey of the impact that a neutron-star radius measurement…

High Energy Astrophysical Phenomena · Physics 2019-08-16 Lukas R. Weih , Elias R. Most , Luciano Rezzolla

The equation of state (EOS) for neutron stars is modeled using the Relativistic Mean Field (RMF) approach with a mesonic nonlinear (NL) interaction, a modified sigma cut potential (NL-$\sigma$ cut), and the influences of dark matter in the…

Nuclear Theory · Physics 2025-05-21 Prashant Thakur , Tuhin Malik , Arpan Das , T. K. Jha , B. K. Sharma , Constança Providência

We present a recent Chandra observation of the quiescent low-mass X-ray binary containing a neutron star, located in the globular cluster M30. We fit the thermal emission from the neutron star to extract its mass and radius. We find no…

High Energy Astrophysical Phenomena · Physics 2020-06-03 Constanza Echiburú , Sebastien Guillot , Yue Zhao , Craig O. Heinke , Feryal Özel , Natalie A. Webb

The equation of state of neutron-rich nuclear matter is of interest to both nuclear physics and astrophysics. We have demonstrated the consistency between laboratory and astrophysical nuclear matter in neutron stars by considering…

Nuclear Theory · Physics 2023-10-06 Zhenyu Zhu , Ang Li , Jinniu Hu , Hong Shen

The understanding of neutron star equation of state hinges on a comprehensive analysis of multi-messenger, multi-wavelength data. The recent scrutiny of PSR J0030+0451 data by NICER introduces complexities, unveiling a tension with another…

High Energy Astrophysical Phenomena · Physics 2024-06-05 Zhiqiang Miao , Liqiang Qi , Juan Zhang , Ang Li , Mingyu Ge

One of the key goals of observing neutron stars is to infer the equation of state (EoS) of the cold, ultradense matter in their interiors. We present here a Bayesian statistical method of inferring the pressures at five fixed densities,…

High Energy Astrophysical Phenomena · Physics 2017-08-09 Carolyn A. Raithel , Feryal Özel , Dimitrios Psaltis