Dense matter with eXTP

Watts, Anna L.; Yu, Wenfei; Poutanen, Juri; Zhang, Shu; Bhattacharyya, Sudip; Bogdanov, Slavko; Ji, Long; Patruno, A.; Riley, Thomas E.; Bakala, Pavel; Baykal, Altan; Bernardini, F.; Bombaci, Ignazio; Brown, Edward F.; Cavecchi, Y.; Chakrabarty, Deepto; Chenevez, J.; Degenaar, N.; Santo, M. Del; Salvo, T. Di; Doroshenko, V.; Falanga, M.; Ferdman, R. D.; Feroci, M.; Gambino, A. F.; Ge, Ming-Yu; Greif, S. K.; Guillot, Sebastien; Güngör, Can; Hartmann, D. H.; Hebeler, K.; Heger, Alexander; Homan, J.; Iaria, R.; Zand, J. in ’t; Kargaltsev, Oleg; Kurkela, Aleksi; Lai, Xiaoyu; Li, Ang; Li, Xiangdong; Li, Zhaosheng; Linares, M.; Lu, Fangjun; Mahmoodifar, Simin; Méndez, Mariano; Miller, M. Coleman; Morsink, Sharon M.; Nättilä, Joonas; Possenti, A.; Prescod-Weinstein, Chanda; Qu, J. L.; Riggio, A.; Salmi, T.; Sanna, A.; Santangelo, A.; Schatz, H.; Schwenk, A.; Song, Liming; Šrámková, Eva; Stappers, B. W.; Stiele, H.; Strohmayer, Tod E.; Tews, Ingo; Tolós, Laura; Török, Gabriel; Tsang, David; Urbanec, Martin; Vacchi, A.; Xu, R. X.; Xu, Y. P.; Zane, S.; Zhang, Guobao; Zhang, Shuang‐Nan; Zhang, Wenda; Zheng, S.; Xiao-Hong, Zhou

doi:10.1007/s11433-017-9188-4

Cited by 117 publications

(89 citation statements)

References 138 publications

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“…The X-ray spectra strongly depends on the distance to the source, its magnetic field and the composition of its atmosphere, hence making the measurement of the radius a rather difficult task. With space missions such as NICER (Neutron star Interior Composition ExploreR) [357] and the future eXTP (enhanced X-ray Timing and Polarimetry) [24], high-precision X-ray astronomy, based on pulse-profile modeling X-ray spectral-timing event data, will offer precise measurements of masses and radii simultaneously. Indeed, the first precise measurement of the size and mass of the millisecond pulsar PSR J0030+0451 has been recently reported by the NICER collaboration, with a mass of M = 1.34 Figure adapted from [24].…”

Section: Observational Constraintsmentioning

confidence: 99%

“…And last but not least, understanding the behaviour of strange mesons and baryons in the presence of a surrounding dense medium is of particular interest to determine the features of the possible phases of dense matter in compact astrophysical objects, such as neutron stars. Neutron stars are one of the most compact astrophysical objects in the universe and, therefore, serve as a unique laboratory for testing matter with strangeness under strong gravitational and magnetic fields, as well as extreme conditions of density, isospin asymmetry and temperature [4,23,24].…”

Section: Introductionmentioning

confidence: 99%

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Strangeness in nuclei and neutron stars

Tolós

Fabbietti

2020

Progress in Particle and Nuclear Physics

173

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We review the present status of the experimental and theoretical developments in the field of strangeness in nuclei and neutron stars. We start by discussing theKN interaction, that is governed by the presence of the Λ(1405). We continue by showing the two-pole nature of the Λ(1405), and the production mechanisms in photon-, pion-, kaon-induced reactions as well as proton-proton collisions, while discussing the formation ofKN N bound states. We then move to the theoretical and experimental analysis of the properties of kaons and antikaons in dense nuclear matter, paying a special attention to kaonic atoms and the analysis of strangeness creation and propagation in nuclear collisions. Next, we examine the φ meson and the advances in photoproduction, protoninduced and pion-induced reactions, so as to understand its properties in dense matter. Finally, we address the dynamics of hyperons with nucleons and nuclear matter, and the connection to the phases of dense matter with strangeness in the interior of neutron stars.

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Section: Observational Constraintsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strangeness in nuclei and neutron stars

Tolós

Fabbietti

2020

Progress in Particle and Nuclear Physics

173

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“…In contrast to masses, radii are extremely difficult to measure because of a limited number of suitable NSs and large systematic and statistical uncertainties [23]. Future observations, e.g., by the NICER [24] and eXTP missions [25], will improve this with target radius uncertainties of 5−10 %, corresponding to 1 km or better [26].…”

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confidence: 99%

Spin-polarized Neutron Matter, the Maximum Mass of Neutron Stars, and GW170817

Tews

Schwenk

2020

ApJ

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We investigate how a phase transition from neutron-star (NS) matter to spin-polarized neutron matter (SPM) affects the equation of state (EOS) and mass-radius relation of NS. While general extension schemes for the EOS allow for high energy densities and pressures inside NSs, we find that a phase transition to SPM excludes extreme regimes in these extensions. Hence, such a phase transition limits the maximum mass of NSs to lie below 2.6−2.9 M , depending on the microscopic nuclear forces used, while significantly larger masses of 3−4 M could be reached without these constraints. Remarkably, this lower maximum mass is in good agreement with recent constraints extracted from the NS merger GW170817 and its electromagnetic counterpart. Assuming the description in terms of SPM to be valid up to densities in the core of NSs, we find that stars with a large spin-polarized domain in their core are ruled out by the gravitational-wave observation GW170817.Motivation.-Neutron star (NS) observations, such as the recent detection of two merging NSs in the gravitational-wave (GW), gamma-ray, and electromagnetic (EM) spectra [1-4], designated as GW170817, GRB 170817A, and AT 2017gfo, respectively, provide crucial constraints on the equation of state (EOS) of dense strongly interacting matter. The EOS is a key quantity for astrophysics and sensitively depends on strong interactions. Hence, it connects astrophysical observations to laboratory experiments at rare isotope beam facilities for the most neutron-rich extremes at RIBF, Japan, and the future FRIB and FAIR facilities in the US and Germany, respectively. While there is a wealth of theoretical models for the EOS of NS matter (see for reviews), obtained from different theories for strong interactions and with various methods, for densities beyond nuclear saturation density n sat ≈ 0.16 fm −3 these models can only be confronted with a limited set of experimental data, e.g., from heavy-ion collisions [8].Neutron stars are the densest objects in the Universe and probe the EOS up to several times saturation density. Neutron-star observations are therefore an ideal source of additional information that complements experimental data and provides powerful constraints for the EOS at higher densities [14,15]. The structure of a NS is described by the mass-radius (M -R) relation, which is an important observational quantity and in a one-to-one correspondence with the EOS: The M -R relation follows from the EOS by solving the Tolman-Oppenheimer-Volkoff (TOV) equations [16,17]. Measuring the M -R relation, and therefore the EOS, observationally is however extremely difficult. On the one hand, NS masses can be determined very precisely for some NSs in binaries [18]. For example, the precise measurement of two two-solar-mass NSs [19-21] established a robust and

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“…We conclude that the new method provides an innovative, independent way of measuring the radius-to-mass ratio of neutron stars with next generation large area X-ray instruments. Though limited to large enough neutron stars in binary systems seen from relatively high inclinations, the method will afford the few percent precision that is required to gather quantitative information on the EoS of matter at supranuclear densities (Watts et al 2019); its precision is also comparable to that of other methods that will be exploited in the same time frame by using X-ray instrumentation of the same type, such as the eXTP/LAD. This is illustrated in Fig.…”

Section: Detecting the Occultation With Future Missionsmentioning

confidence: 99%

“…Despite considerable progress in recent years, radius (or combined mass and radius) measurements have not yet attained the required level of accuracy and precision to univocally determine the EoS (e.g. Watts et al 2019). Limitations involve systematics, insufficient signal-to-noise or resolution, modelling uncertainties and scarcity of suitable systems or events.…”

Section: Introductionmentioning

confidence: 99%

Neutron Star Radius-to-mass Ratio from Partial Accretion Disk Occultation as Measured through Fe Kα Line Profiles

Placa

Stella

Papitto

et al. 2020

ApJ

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We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, discaccreting neutron stars by exploiting the occultation of parts of the inner disc by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low mass X-ray binary systems seen under inclinations higher than~65 degrees. We analyse a NuSTAR observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to~2 ÷ 3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods too aim to achieve in the future.

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Dense matter with eXTP

Cited by 117 publications

References 138 publications

Strangeness in nuclei and neutron stars

Strangeness in nuclei and neutron stars

Spin-polarized Neutron Matter, the Maximum Mass of Neutron Stars, and GW170817

Neutron Star Radius-to-mass Ratio from Partial Accretion Disk Occultation as Measured through Fe Kα Line Profiles

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