Effective area calibration of the Nuclear Spectroscopic Telescope Array

Madsen, K. K.; Grefenstette, Brian W.; Harrison, Fiona A.; Miyasaka, Hiromasa

doi:10.1117/1.jatis.8.3.034003

Cited by 24 publications

(12 citation statements)

References 22 publications

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“…We obtained that the FPMA fluxes in the 3-10 keV were slightly (≈ 5%) higher than for FPMB (with a 1-σ significance), while in the 10-25 keV range the fluxes between both cameras match up to 2% and this difference is less significant (< 1σ). This is within the calibration uncertainties of the instrument (Madsen et al 2015(Madsen et al , 2022. From these tests we concluded that both observations are compatible but with a small difference between the cameras.…”

Section: Nustarsupporting

confidence: 77%

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

Palacio

García

Becker

et al. 2023

A&A

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Context. Massive colliding-wind binaries (CWBs) can be non-thermal sources. The emission produced in their wind-collision region (WCR) encodes information of both the shocks properties and the relativistic electrons accelerated in them. The recently discovered system Apep, a unique massive system hosting two Wolf-Rayet stars, is the most powerful synchrotron radio emitter among the known CWBs, being an exciting candidate to investigate the non-thermal processes associated with stellar wind shocks. Aims. We intend to break the degeneracy between the relativistic particle population and the magnetic field strength in the WCR of Apep by probing its hard X-ray spectrum, where inverse-Compton (IC) emission is expected to dominate. Methods. We observe Apep with NuSTAR for 60 ks and combine this with a re-analysis of a deep archival XMM-Newton observation to better constrain the X-ray spectrum. We use a non-thermal emission model to derive physical parameters from the results. Results. We detect hard X-ray emission consistent with a power-law component from Apep. This is compatible with IC emission produced in the WCR for a magnetic field of ≈ 105-190 mG, corresponding to a magnetic-to-thermal pressure ratio in the shocks of ≈ 0.007-0.021, and a fraction of ∼ 1.5 × 10 −4 of the total wind kinetic power being transferred to relativistic electrons. Conclusions. This is the first time that the non-thermal emission from a CWB is detected both in radio and high energies. This allows us to derive the most robust constraints of the particle acceleration efficiency and magnetic field intensity in a CWB so far, reducing the typical uncertainty of a few orders of magnitude to just within a factor of a few. This constitutes an important step forward in our characterisation of the physical properties of CWBs.

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Section: Nustarsupporting

confidence: 77%

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

Palacio

García

Becker

et al. 2023

A&A

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“…To take into account NuSTAR calibration uncertainties (Madsen et al 2022), we assumed a gain offset free in the fit, obtaining −(0.085 ± 0.009) keV and −(0.068 ± 0.008) keV for the focal plane modules Aand B(FPMA and FPMB), respectively; similarly for IXPE calibration uncertainties (Di Marco et al 2022b), we left free the gain slope and offset obtaining a slope of 0.981 ± 0.003, 0.973 ± 0.003, 0.980 ± 0.003 keV −1 for the DU1, DU2, and DU3 respectively, while the offset in each one is 0.003 ± 0.012, 0.032 ± 0.012, and 0.020 ± 0.012 keV. As reported also by the photons fluxes of Table 2, the spectrum in the whole 2-8 keV IXPE energy band is dominated by the Comptonization component, while the disk contributes only at lower energies (see also Figure 8).…”

Section: Spectral Analysismentioning

confidence: 99%

First Detection of X-Ray Polarization from the Accreting Neutron Star 4U 1820−303

Marco

Monaca

Poutanen

et al. 2023

ApJL

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This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820−303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed in the radio with the Australia Telescope Compact Array. The IXPE observations of 4U 1820−303 were coordinated with Swift X-ray Telescope, Neutron Star Interior Composition Explorer, and Nuclear Spectroscopic Telescope Array aiming to obtain an accurate X-ray spectral model covering a broad energy interval. The source shows a significant polarization above 4 keV, with a polarization degree of 2.0% ± 0.5% and a polarization angle of −55° ± 7° in the 4–7 keV energy range, and a polarization degree of 10% ± 2% and a polarization angle of −67° ± 7° in the 7–8 keV energy bin. This polarization also shows a clear energy trend with polarization degree increasing with energy and a hint for a position-angle change of ≃90° at 96% CL around 4 keV. The spectro-polarimetric fit indicates that the accretion disk is polarized orthogonally to the hard spectral component, which is presumably produced in the boundary/spreading layer. We do not detect linear polarization from the radio counterpart, with a 3σ upper limit of 50% at 7.25 GHz.

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“…Of the NuSTAR observations shown, this work is focused on the observation with the highest count rate, shown in red. (Madsen et al 2022), and does not occur when the data are processed with previous CALDB versions. The detector response is calculated across each FPM without taking into account pixel-to-pixel variations, which is responsible for the small differences (2%) seen in the MAXI J1803 spectra.…”

Section: Spectral Analysismentioning

confidence: 99%

Reflection and Timing Study of the Transient Black Hole X-Ray Binary MAXI J1803-298 with NuSTAR

Tomsick

Mastroserio

et al. 2023

ApJ

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The transient black hole X-ray binary MAXI J1803−298 was discovered on 2021 May 1, as it went into outburst from a quiescent state. As the source rose in flux it showed periodic absorption dips and fit the timing and spectral characteristics of a hard-state accreting black hole. We report on the results of a Target-of-Opportunity observation with NuSTAR obtained near the peak outburst flux beginning on 2021 May 13, after the source had transitioned into an intermediate state. MAXI J1803−298 is variable across the observation, which we investigate by extracting spectral and timing products separately for different levels of flux throughout the observation. Our timing analysis reveals two distinct potential quasiperiodic oscillations (QPOs) which are not harmonically related at 5.4 ± 0.2 Hz and 9.4 ± 0.3 Hz, present only during periods of lower flux. With clear relativistic reflection signatures detected in the source spectrum, we applied several different reflection models to the spectra of MAXI J1803−298. Here we report our results, utilizing high-density reflection models to constrain the disk geometry, and assess changes in the spectrum dependent on the source flux. With a standard broken power-law emissivity, we find a near-maximal spin for the black hole, and we are able to constrain the inclination of the accretion disk at 75° ± 2°, which is expected for a source that has shown periodic absorption dips. We also significantly detect a narrow absorption feature at 6.91 ± 0.06 keV with an equivalent width between 4 and 9 eV, which we interpret as the signature of a disk wind.

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Effective area calibration of the Nuclear Spectroscopic Telescope Array

Cited by 24 publications

References 22 publications

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

Evidence for non-thermal X-ray emission from the double Wolf-Rayet colliding-wind binary Apep

First Detection of X-Ray Polarization from the Accreting Neutron Star 4U 1820−303

Reflection and Timing Study of the Transient Black Hole X-Ray Binary MAXI J1803-298 with NuSTAR

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