On joint analysing XMM-NuSTAR spectra of active galactic nuclei
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2023
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| _version_ | 1866916452692393984 |
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| author | Kang, Jia-Lai Wang, Jun-Xian |
| author_facet | Kang, Jia-Lai Wang, Jun-Xian |
| contents | 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 $ΔΓ\sim 0.1$, 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 $Γ$, $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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_15499 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | On joint analysing XMM-NuSTAR spectra of active galactic nuclei Kang, Jia-Lai Wang, Jun-Xian High Energy Astrophysical Phenomena Astrophysics of Galaxies Instrumentation and Methods for Astrophysics 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 $ΔΓ\sim 0.1$, 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 $Γ$, $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. |
| title | On joint analysing XMM-NuSTAR spectra of active galactic nuclei |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2311.15499 |