Return to the forgotten ULX: a broadband NICER+NuSTAR study of NGC 4190 ULX-1
arxiv(2024)
摘要
We observed the nearby and relatively understudied ultraluminous X-ray source
(ULX) NGC 4190 ULX-1 jointly with NICER and NuSTAR to investigate its broadband
spectrum, timing properties, and spectral variation over time. We found NGC
4190 ULX-1 to have a hard spectrum characterized by two thermal components
(with temperatures 0.25keV and 1.6keV) and a high-energy excess typical of
the ULX population, although the spectrum turns over at an unusually low
energy. While no pulsations were detected, the source shows significant
stochastic variability and the covariance spectrum indicates the presence of a
high-energy cut-off power-law component, potentially indicative of an accretion
column. Additionally, when fitting archival XMM-Newton data with a similar
model, we find that the luminosity-temperature evolution of the hot thermal
component follows the behavior of a super-Eddington slim disk though the
expected spectral broadening for such a disk is not seen, suggesting that the
inner accretion disk may be truncated by a magnetic field. Therefore, despite
the lack of detected pulsations, there is tantalizing evidence for NGC 4190
ULX-1 being a candidate neutron star accretor, although further broadband
observations will be required to confirm this behavior.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要