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NuSTAR Spectral Analysis beyond 79 keV with Stray Light

Mastroserio, G. and Grefenstette, B. W. and Thalhammer, P. and Buisson, D. J. K. and Brumback, M. C. and Ludlam, R. M. and Connors, R. M. T. and García, J. A. and Grinberg, V. and Madsen, K. K. and Miyasaka, H. and Tomsick, J. A. and Wilms, J. (2022) NuSTAR Spectral Analysis beyond 79 keV with Stray Light. Astrophysical Journal, 941 (1). Art. No. 35. ISSN 0004-637X. doi:10.3847/1538-4357/ac8c94.

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Due to the structure of the NuSTAR telescope, photons at a large off axis (>1°) can reach the detectors directly (stray light), without passing through the instrument optics. At these off-axis angles NuSTAR essentially turns into a collimated instrument and the spectrum can extend to energies above the Pt K edge (79 keV) of the multilayers, which limits the effective area bandpass of the optics. We present the first scientific spectral analysis beyond 79 keV using a Cygnus X-1 observation in StrayCats: the catalog of stray light observations. This serendipitous stray light observation occurred simultaneously with an INTEGRAL observation. When the spectra are modeled together in the 30–120 keV energy band, we find that the NuSTAR stray light flux is well calibrated and constrained to be consistent with the INTEGRAL flux at the 90% confidence level. Furthermore, we explain how to treat the background of the stray light spectral analysis, which is especially important at high energies.

Item Type:Article
Related URLs:
URLURL TypeDescription
Mastroserio, G.0000-0003-4216-7936
Grefenstette, B. W.0000-0002-1984-2932
Thalhammer, P.0000-0001-6269-2821
Buisson, D. J. K.0000-0002-5341-6929
Brumback, M. C.0000-0002-4024-6967
Ludlam, R. M.0000-0002-8961-939X
Connors, R. M. T.0000-0002-8908-759X
García, J. A.0000-0003-3828-2448
Grinberg, V.0000-0003-2538-0188
Madsen, K. K.0000-0003-1252-4891
Miyasaka, H.0000-0002-8074-4186
Tomsick, J. A.0000-0001-5506-9855
Wilms, J.0000-0003-2065-5410
Additional Information:G.M. would like to thank Lorenzo Natalucci for the helpful comments. J.A.G. acknowledges support from NASA grant 80NSSC19K1020 and from the Alexander von Humboldt Foundation. The material is based upon work supported by NASA under award No. 80GSFC21M0002. This work was supported by NASA under grant No. 80NSSC19K1023 issued through the NNH18ZDA001N Astrophysics Data Analysis Program (ADAP). This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA).
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20230203-893210800.24
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:119018
Deposited By: Research Services Depository
Deposited On:24 Feb 2023 21:29
Last Modified:24 Feb 2023 21:29

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