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On joint analysing XMM-NuSTAR spectra of active galactic nuclei
High Energy Astrophysical Phenomena · Submitted 27 Nov 2023
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We confirm the correction is highly effective and can commendably erase the discrepancy in best-fit $\Gamma$, $E_{\rm cut} $ and R, and thus we urge the community to apply the correction when joint-fitting XMM-NuSTAR spectra.
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The abstract, sentence by sentence
A recently released XMM-Newton technical note has revealed a significant calibration issue between NuSTAR and XMM-Newton EPIC, and provided an empirical correction to EPIC effective area. To quantify the bias caused by the calibration issue to joint analysis of XMM-NuSTAR spectra and verify the effectiveness of the correction, in this work we perform joint-fitting of NuSTAR and EPIC-pn spectra for a large sample of 104 observation pairs of 44 X-ray bright AGN. The spectra were extracted after requiring perfect simultaneity between XMM-Newton and NuSTAR exposures (merging GTIs from two missions) to avoid bias due to rapid spectral variability of AGN. Before the correction, the EPIC-pn spectra are systematically harder than corresponding NuSTAR spectra by $\Delta \Gamma \sim 0.1$, subsequently yielding significantly underestimated cutoff energy $E_{\rm cut} $ and the strength of reflection component R when performing joint-fitting. We confirm the correction is highly effective and can commendably erase the discrepancy in best-fit $\Gamma$, $E_{\rm cut} $ and R, and thus we urge the community to apply the correction when joint-fitting XMM-NuSTAR spectra. Besides, we show that as merging GTIs from two missions would cause severe loss of NuSTAR net exposure time, in many cases joint-fitting yields no advantage compared with utilizing NuSTAR data alone. We finally present a technical note on filtering periods of high background flares for XMM-Newton EPIC-pn exposures in the Small Window mode.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | A recently released XMM-Newton technical note has revealed a significant calibration issue between NuSTAR and XMM-Newton EPIC, and provided an empirical correction to EPIC effective area. | background 1.00 | 0.05 | 0.04 | asserted 1.00 |
| s1 | To quantify the bias caused by the calibration issue to joint analysis of XMM-NuSTAR spectra and verify the effectiveness of the correction, in this work we perform joint-fitting of NuSTAR and EPIC-pn spectra for a large sample of 104 observation pairs of 44 X-ray bright AGN. | contribution 0.85 | 0.88 | 0.05 | asserted 0.93 |
| s2 | The spectra were extracted after requiring perfect simultaneity between XMM-Newton and NuSTAR exposures (merging GTIs from two missions) to avoid bias due to rapid spectral variability of AGN. | method 1.00 | 0.92 | 0.03 | asserted 0.99 |
| s3 | Before the correction, the EPIC-pn spectra are systematically harder than corresponding NuSTAR spectra by $\Delta \Gamma \sim 0.1$, subsequently yielding significantly underestimated cutoff energy $E_{\rm cut} $ and the strength of reflection component R when performing joint-fitting. | result 0.99 | 0.88 | 0.11 | asserted 1.00 |
| s4 | We confirm the correction is highly effective and can commendably erase the discrepancy in best-fit $\Gamma$, $E_{\rm cut} $ and R, and thus we urge the community to apply the correction when joint-fitting XMM-NuSTAR spectra. | result 0.72 | 0.94 | 0.78 | asserted 1.00 |
| s5 | Besides, we show that as merging GTIs from two missions would cause severe loss of NuSTAR net exposure time, in many cases joint-fitting yields no advantage compared with utilizing NuSTAR data alone. | result 0.52 | 0.93 | 0.09 | asserted 0.99 |
| s6 | We finally present a technical note on filtering periods of high background flares for XMM-Newton EPIC-pn exposures in the Small Window mode. | contribution 0.97 | 0.82 | 0.03 | asserted 0.93 |
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Original abstract
A recently released XMM-Newton technical note has revealed a significant calibration issue between NuSTAR and XMM-Newton EPIC, and provided an empirical correction to EPIC effective area. To quantify the bias caused by the calibration issue to joint analysis of XMM-NuSTAR spectra and verify the effectiveness of the correction, in this work we perform joint-fitting of NuSTAR and EPIC-pn spectra for a large sample of 104 observation pairs of 44 X-ray bright AGN. The spectra were extracted after requiring perfect simultaneity between XMM-Newton and NuSTAR exposures (merging GTIs from two missions) to avoid bias due to rapid spectral variability of AGN. Before the correction, the EPIC-pn spectra are systematically harder than corresponding NuSTAR spectra by $\Delta \Gamma \sim 0.1$, subsequently yielding significantly underestimated cutoff energy $E_{\rm cut} $ and the strength of reflection component R when performing joint-fitting. We confirm the correction is highly effective and can commendably erase the discrepancy in best-fit $\Gamma$, $E_{\rm cut} $ and R, and thus we urge the community to apply the correction when joint-fitting XMM-NuSTAR spectra. Besides, we show that as merging GTIs from two missions would cause severe loss of NuSTAR net exposure time, in many cases joint-fitting yields no advantage compared with utilizing NuSTAR data alone. We finally present a technical note on filtering periods of high background flares for XMM-Newton EPIC-pn exposures in the Small Window mode.
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4 arXiv papers cite this in 6 sentences
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Uses its method or tool 2 papers
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Following the procedures described in [ref] , we filter out high background intervals, and extract the source spectra within a circular region with a radius of 60, and the background from nearby source-free regions.
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Ancillary response files were generated with arfgen, enabling applyabsfluxcorr=yes to improve the /cross-calibration [ref] .
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