NICER Observation of Unusual Burst Oscillations in 4U 1728-34
Name
Mahmoodifar_2019_ApJ_878_145.pdf
Description
Published version
Size
501.77 KB
Format
Adobe PDF
Checksum (MD5)
26a5748095c8d756d4b8cf9a6212d376
Author(s)
Mahmoodifar, Simin
Strohmayer, Tod E
Bult, Peter
Altamirano, Diego
Arzoumanian, Zaven
Chakrabarty, Deepto
Gendreau, Keith C
Guillot, Sebastien
Homan, Jeroen
Jaisawal, Gaurava K
Date Issued
2019
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Version
Final published version
Abstract
© 2019. The American Astronomical Society. All rights reserved. The Neutron Star Interior Composition Explorer has observed seven thermonuclear X-ray bursts from the low-mass X-ray binary neutron star 4U 1728-34 from the start of the mission's operations until 2019 February. Three of these bursts show oscillations in their decaying tail, with frequencies that are within 1 Hz of the previously detected burst oscillations from this source. Two of these burst oscillations have unusual properties: they have large fractional root mean square (rms) amplitudes of 48% ± 9% and 46% ± 9%, and they are detected only at photon energies above 6 keV. By contrast, the third detected burst oscillation is compatible with previous observations of this source, with a fractional rms amplitude of 7.7% ± 1.5% rms in the 0.3 to 6.2 keV energy band. We discuss the implications of these large-amplitude burst oscillations, finding that they are difficult to explain with the current theoretical models for X-ray burst tail oscillations.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.3847/1538-4357/AB20C4
