TY - JOUR
T1 - NICER Observes a Secondary Peak in the Decay of a Thermonuclear Burst from 4U 1608–52
AU - Jaisawal, Gaurava K.
AU - Chenevez, Jérôme
AU - Bult, Peter
AU - in’t Zand, Jean J. M.
AU - Galloway, Duncan K.
AU - Strohmayer, Tod E.
AU - Güver, Tolga
AU - Adkins, Phillip
AU - Altamirano, Diego
AU - Arzoumanian, Zaven
AU - Chakrabarty, Deepto
AU - Coopersmith, Jonathan
AU - Gendreau, Keith C.
AU - Guillot, Sebastien
AU - Keek, Laurens
AU - Ludlam, Renee M.
AU - Malacaria, Christian
PY - 2019
Y1 - 2019
N2 - 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.
AB - 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.
KW - Accretion
KW - Accretion disks
KW - Stars: individual (4U 1608-52)
KW - Stars: neutron
KW - X-rays: binaries
KW - X-rays: bursts
U2 - 10.3847/1538-4357/ab3a37
DO - 10.3847/1538-4357/ab3a37
M3 - Journal article
VL - 883
JO - Astrophysical Journal Supplement Series
JF - Astrophysical Journal Supplement Series
SN - 0067-0049
IS - 1
M1 - 61
ER -