The impact of precession on the observed population of ULXs

Khan, Norman; Middleton, Matthew; Wiktorowicz, Grzegorz; Dauser, Thomas; Roberts, T. P.; Wilms, J.

doi:10.1093/mnras/stab3049

Cited by 7 publications

(7 citation statements)

References 89 publications

(140 reference statements)

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“…This behavior is similar to that seen in the long-term X-ray flux variations of ULX pulsar NGC 7793 P13 (Fürst et al 2021). For both ULX-1 and NGC 7793 P13, the authors conjectured that this behavior was due to obscuration of the pulsar, possibly due to an outflow (Kosec et al 2018) or Lense-Thirring precession of the inner accretion disk (Middleton et al 2018(Middleton et al , 2019Khan et al 2022). This supported the work by Carpano et al (2018), who found a large difference in absorption column density between X-ray observations in 2010 (XMM-Newton) and 2016 (XMM-Newton and NuS-TAR), while keeping other spectral parameters tied.…”

Section: Introductionsupporting

confidence: 72%

Spectral Evolution of Ultraluminous X-Ray Pulsar NGC 300 ULX-1

Remillard

Steiner

et al. 2022

ApJ

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We report on results from a 1 yr soft X-ray observing campaign of the ultraluminous X-ray pulsar NGC 300 ULX-1 by the Neutron star Interior Composition Explorer (NICER) during 2018–2019. Our analysis also made use of data from Swift/XRT and XMM-Newton in order to model and remove contamination from the nearby eclipsing X-ray binary NGC 300 X-1. We constructed and fitted a series of 5 day averaged NICER spectra of NGC 300 ULX-1 in the 0.4–4.0 keV range to evaluate the long-term spectral evolution of the source, and we found that an absorbed power-law model provided the best fit overall. Over the course of our observations, the source flux (0.4–4.0 keV; absorbed) dimmed from 2 × 10−12 to below 10−13 erg s−1 cm−2 and the spectrum softened, with the photon index going from Γ ≈ 1.6 to Γ ≈ 2.6. We interpret the spectral softening as reprocessed emission from the accretion disk edge coming into view while the pulsar was obscured by the possibly precessing disk. Some spectral fits were significantly improved by the inclusion of a disk blackbody component, and we surmise that this could be due to the pulsar emerging in between obscuration episodes by partial covering absorbers. We posit that we observed a low-flux state of the system (due to line-of-sight absorption) punctuated by the occasional appearance of the pulsar, indicating short-term source variability nested in longer-term accretion disk precession timescales.

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Section: Introductionsupporting

confidence: 72%

Spectral Evolution of Ultraluminous X-Ray Pulsar NGC 300 ULX-1

Remillard

Steiner

et al. 2022

ApJ

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show abstract

“…This behavior is similar to that seen in the long-term X-ray flux variations of ULX pulsar NGC 7793 P13 (Fürst et al 2021). For both ULX-1 and NGC 7793 P13, the authors conjectured that this behavior was due to obscuration of the pulsar possibly due to an outflow (Kosec et al 2018) or Lense-Thirring precession of the inner accretion disk (Middleton et al 2018(Middleton et al , 2019Khan et al 2022). This supported the work by Carpano et al (2018), who found a large difference in absorption column density between X-ray observations in 2010 (XMM-Newton) and 2016 (XMM-Newton and NuSTAR), while keeping other spectral parameters tied.…”

Section: Introductionsupporting

confidence: 72%

Spectral Evolution of Ultraluminous X-ray Pulsar NGC 300 ULX-1

Ng,

Remillard,

Steiner

et al. 2022

Preprint

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We report on results from a one-year soft X-ray observing campaign of the ultraluminous X-ray pulsar NGC 300 ULX-1 by the Neutron star Interior Composition Explorer (NICER) during 2018-2019. Our analysis also made use of data from Swift/XRT and XMM-Newton in order to model and remove contamination from the nearby eclipsing X-ray binary NGC 300 X-1. We constructed and fitted a series of 5-day averaged NICER spectra of NGC 300 ULX-1 in the 0.4-4.0 keV range to evaluate the long-term spectral evolution of the source, and found that an absorbed power-law model provided the best fit overall. Over the course of our observations, the source flux (0.4-4.0 keV; absorbed) dimmed from 2 × 10 −12 to below 10 −13 erg s −1 cm −2 and the spectrum softened, with the photon index going from Γ ≈ 1.6 to Γ ≈ 2.6. We interpret the spectral softening as reprocessed emission from the accretion disk edge coming into view while the pulsar was obscured by the possibly precessing disk. Some spectral fits were significantly improved by the inclusion of a disk blackbody component, and we surmise that this could be due to the pulsar emerging in between obscuration episodes by partial covering absorbers. We posit that we observed a low-flux state of the system (due to line-of-sight absorption) punctuated by the occasional appearance of the pulsar, indicating short-term source variability nested in longer-term accretion disk precession timescales.

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“…XLFs can also be directly compared with population synthesis calculations which include the evolution of systems through their various phases (including mass transfer, common envelope, SNe and gravitational inspiral). Recent attempts include those by Wiktorowicz et al (2019) where the effect of geometrical beaming (following equation 55) is included, Khan et al (2021), where the observational impact of precession is considered (see below), and Kuranov et al (2020) who obtain the XLF for magnetised neutron stars in the absence of beaming and precession of the wind-cone (see section 2.3.3).…”

Section: Catalogues and X-ray Surveysmentioning

confidence: 99%