NICER Observes a Secondary Peak in the Decay of a Thermonuclear Burst from 4U 1608–52
Name
Jaisawal_2019_ApJ_883_61.pdf
Description
Published version
Size
1.16 MB
Format
Adobe PDF
Checksum (MD5)
9e60c3b3cab1e6a8609a244c1e7eb2c2
Author(s)
Jaisawal, Gaurava K
Chenevez, Jérôme
Bult, Peter
in’t Zand, Jean JM
Galloway, Duncan K
Strohmayer, Tod E
Güver, Tolga
Adkins, Phillip
Altamirano, Diego
Arzoumanian, Zaven
Date Issued
2019
Journal
Astrophysical Journal
Publisher
American Astronomical Society
Version
Final published version
Abstract
© 2019. The American Astronomical Society. All rights reserved. We report for the first time below 1.5 keV, the detection of a secondary peak in an Eddington-limited thermonuclear X-ray burst observed by the Neutron Star Interior Composition Explorer (NICER) from the low-mass X-ray binary 4U 1608-52. Our time-resolved spectroscopy of the burst is consistent with a model consisting of a varying-temperature blackbody, and an evolving persistent flux contribution, likely attributed to the accretion process. The dip in the burst intensity before the secondary peak is also visible in the bolometric flux. Prior to the dip, the blackbody temperature reached a maximum of ≈3 keV. Our analysis suggests that the dip and secondary peak are not related to photospheric expansion, varying circumstellar absorption, or scattering. Instead, we discuss the observation in the context of hydrodynamical instabilities, thermonuclear flame spreading models, and reburning in the cooling tail of the burst.
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/AB3A37
