Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session J06: NICER and the Mass-radius Relation of Neutron StarsInvited Live
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Sponsoring Units: DGRAV DNP Chair: David Nice, Lafayette College Room: Roosevelt 1 |
Sunday, April 19, 2020 1:30PM - 2:06PM Live |
J06.00001: NICER constraints on neutron star mass and radius Invited Speaker: Wynn C.G. Ho Measurements of the mass and radius of neutron stars provide crucial insights into properties of matter at supranuclear densities, including the nuclear equation of state. Such measurements are a key mission objective of NICER, which is a precision timing X-ray instrument that was mounted on the International Space Station in June 2017. The NICER science team recently announced the first results on this objective using almost two megaseconds of data on the neutron star PSR J0030+0451. In this talk, I provide a brief overview of NICER and summarize the recent results on mass and radius, as well as report on ongoing efforts to measure the mass and radius of other neutron stars. [Preview Abstract] |
Sunday, April 19, 2020 2:06PM - 2:42PM Live |
J06.00002: What NICER tells us about pulsar emission and magnetic fields Invited Speaker: Anna Bilous We review the results of the recent modeling of soft thermal X-ray pulsations from the surface of the isolated millisecond pulsar PSR J0030$+$0451, observed by Neutron Star Interior Composition Explorer. Obtained independently by two research groups (Riley et al. 2019, Miller et al. 2019), the locations and shapes of emitting hot regions can not, to our best knowledge, be reconciled with heating by the magnetospheric currents at the footpoints of open field lines in canonical dipolar models of pulsar magnetic fields. Developing models of physically motivated, non-dipolar magnetic field configurations and the currents that they can support poses a challenging task. However, such models may have profound implications for the interpretation of observational data for many aspects of pulsar research, including pulsar braking, estimates of birth velocities, and multi-wavelength magnetospheric emission. [Preview Abstract] |
Sunday, April 19, 2020 2:42PM - 3:18PM Live |
J06.00003: Neutron Star Masses and Radii and the Equation of State of Dense Matter Invited Speaker: Andrew Steiner The idea that neutron observations can be used to determine the equation of state of dense matter precedes the observation of the first neutron star by almost a decade. However, only in the past ten years have neutron star mass and radius measurements led to quantitative constraints on the equation of state over a range of densities. In this talk, we present a quantitative analysis of neutron star mass and radius measurements from quiescent low-mass X-ray binaries and photospheric radius expansion bursts. We combine this information with tidal deformability constraints from GW 170817 and recent constraints from NICER on the mass and radius of J0030+451 to obtain a probability distribution of mass-radius curves. We also obtain a probability distribution for the equation of state. Finally, we examine the impact of statistical and systematic uncertainties in these determinations. [Preview Abstract] |
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