Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method

Nättilä, Joonas; Steiner, Andrew W.; Kajava, J. J. E.; Suleimanov, V.; Poutanen, Juri

doi:10.1051/0004-6361/201527416

Cited by 126 publications

(190 citation statements)

References 53 publications

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“…The DU processes start for M > M DU 1.88 M what corresponds to a central density of n cen 5 n 0 . The radius of the 1.4M NS is about 12 km, agreeing with the analysis of NS data in [67] and with a recent analysis using the cooling tail method [68], see also Ref. [9] and the contribution to this volume [69].…”

Section: Equation Of Statesupporting

confidence: 89%

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

2016

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Abstract. Measurements of the low masses for the pulsar PSR J0737-3039B, for the companion of PSR J1756-2251 and for the companion of PSR J0453+1559 on the one hand and of the high masses for the pulsars PSR J1614-2230 and PSR J0348-0432 on the other demonstrate the existence of compact stars with masses in a broad range from 1.2 to 2 M . The most massive of these objects might be hybrid stars. To fulfill the constraint Mmax > 2 M with a reserve we exploit the stiff DD2 hadronic equation of state (EoS) without and with excluded volume (DD2vex) correction, which produce maximum neutron star masses of Mmax = 2.43 M and 2.70 M , respectively. We show that the stiffness of the EoS does not preclude an explanation of the whole set of cooling data within "nuclear medium cooling" scenario for compact stars by a variation of the star masses. We select appropriate proton gap profiles from those exploited in the literature and allow for a variation of the effective pion gap controlling the efficiency of the medium modified Urca process. However, we suppress the possibility of pion condensation. In general, the stiffer the EoS the steeper a decrease with density of the effective pion gap is required. Results are compared with previously obtained ones for the HDD EoS for which Mmax = 2.06 M . The cooling of the compact star in the supernova remnant Cassiopeia A (Cas A) is explained mainly by an efficient medium modified Urca process. To explain a > ∼ 2.5% decline of the cooling curve for Cas A, as motivated by an analysis of the ACIS-S instrument data, together with other cooling data exploiting the DD2 EoS a large proton gap at densities n < ∼ 2n0 is required vanishing for n > ∼ 2.5 n0, where n0 is the saturation nuclear density. A smaller decline, as it follows from an analysis of the HRC-S instrument data, is explained with many choices of parameters. With the DD2vex EoS and using an effective pion gap steeper decreasing with the density and/or a proton gap shifted to smaller densities we are also able to reproduce both a strong decline compatible with ACIS-S data and HRC-S instrument data. The mass of Cas A is estimated as 1.6 − 1.9 M , above the value 1.5 M , which we have evaluated with the softer HDD equation of state. Different mass choices for the hottest object XMMU J173203.3-344518 are discussed. We make general remarks also on hybrid star cooling and on its dependence on the stiffness of the hadronic EoS.PACS. 97.60.Jd Neutron stars -95.30.Cq Elementary particle processes -26.60-c Nuclear matter aspects of neutron stars

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Section: Equation Of Statesupporting

confidence: 89%

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

2016

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“…Poutanen et al 2014;Nättilä et al 2016). We have observed that the emission level above 40 keV drops by a factor of three during the Xray burst, causing an integrated flux loss of F loss ∼ 3.6 × 10 −10 erg cm −2 s −1 in the 40−200 keV band.…”

Section: Discussionmentioning

confidence: 82%

X-ray burst-induced spectral variability in 4U 1728–34

Kajava

Sánchez–Fernández

Kuulkers

et al. 2017

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Aims. INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time INTEGRAL has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, a.k.a. "the slow burster". Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods. We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results. We constructed a hardness intensity diagram to track spectral state variations. In the soft state the energy spectra are characterized by two thermal components -likely from the accretion disc and the boundary/spreading layer -together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the ∼40 to 80 keV range. In the hard state the source is detected up to ∼200 keV and the spectrum can be described by a thermal Comptonization model plus an additional component: either a powerlaw tail or reflection. By stacking 123 X-ray bursts in the hard state, we detect emission up to 80 keV during the X-ray bursts. We find that during the bursts the emission above 40 keV decreases by a factor of about three with respect to the persistent emission level. Conclusions. Our results suggest that the enhanced X-ray burst emission changes the spectral properties of the accretion disc in the hard state. The likely cause is an X-ray burst induced cooling of the electrons in the inner hot flow near the neutron star.

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“…The gray strip represents the mass of the NS PSR J0348 + 0432, M J0348+0432 = 2.01 ± 0.04M [79]. The yellow region indicates the NS mass-radius constraints from model A of Nättilä et al [12]. Besides the LS220 parametrization, only SLy4 and (barely) KDE0v1 and NRAPR satisfy the M max 2 M constraint.…”

Section: -13mentioning

confidence: 99%

Open-source nuclear equation of state framework based on the liquid-drop model with Skyrme interaction

2017

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The equation of state (EOS) of dense matter is an essential ingredient for numerical simulations of core-collapse supernovae and neutron star mergers. The properties of matter near and above nuclear saturation density are uncertain, which translates into uncertainties in astrophysical simulations and their multimessenger signatures. Therefore, a wide range of EOSs spanning the allowed range of nuclear interactions are necessary for determining the sensitivity of these astrophysical phenomena and their signatures to variations in input microphysics. We present a new set of finite temperature EOSs based on experimentally allowed Skyrme forces. We employ a liquid-drop model of nuclei to capture the nonuniform phase of nuclear matter at subsaturation density, which is blended into a nuclear statistical equilibrium EOS at lower densities. We also provide a new, open-source code for calculating EOSs for arbitrary Skyrme parametrizations. We then study the effects of different Skyrme parametrizations on thermodynamical properties of dense astrophysical matter, the neutron star mass-radius relationship, and the core collapse of 15 and 40 solar mass stars.

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Equation of state constraints for the cold dense matter inside neutron stars using the cooling tail method

Cited by 126 publications

References 53 publications

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

Influence of the stiffness of the equation of state and in-medium effects on the cooling of compact stars

X-ray burst-induced spectral variability in 4U 1728–34

Open-source nuclear equation of state framework based on the liquid-drop model with Skyrme interaction

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