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Special Seminar

August

15

Utilizing NICER & NuSTAR for Neutron Star Low-mass X-ray Binaries
Renee Ludlam (University of Michigan)

Abstract: Over the past several years we have been able to perform inner disk measurements with NuSTAR that are unbiased by pile-up effects. From these measurements we are able to infer different properties about the neutron star itself, such as magnetic field strengths, boundary layers, and constraints on the equation of state. Observations of a number of neutron stars over range of Eddington ratios has allowed us to probe the extent of the inner disk over a range of mass accretion rates. There does not appear to be a clear trend between mass accretion rate and the location of the inner disk radius, consistent with several previous studies that were complicated by pile-up effects. When comparing the magnetic field strengths from reflection modeling methods to those seen for accreting millisecond X-ray pulsars (AMXPs), we find the magnetic field strengths to be consistent over comparable Eddington ratios; demonstrating that Fe lines can be used to place limits to first order. With the addition of NICER, we gain access to lower energy features below 3 keV that are also free from pile-up effects. Utilizing the combined passband and sensitivity of both NuSTAR and NICER opens a new opportunity to capture multiple emission features arising from bright sources to map out different observables within the disk and disentangle truncation mechanisms in systems.

 
Date August 15, 2018
Start/End Time 01:30 PM - 02:30 PM
Location B34, E215
Event Type Seminars/Colloquia
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