CaltechAUTHORS
Published December 10, 2022 | Version public
Journal Article Metadata-only

NuSTAR Spectral Analysis beyond 79 keV with Stray Light

Creators

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon University of Erlangen-Nuremberg
  • 3. ROR icon Wayne State University
  • 4. ROR icon European Space Research and Technology Centre
  • 5. ROR icon Goddard Space Flight Center
  • 6. ROR icon University of California, Berkeley

Abstract

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.

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).

Additional details

Identifiers

Eprint ID
119018
Resolver ID
CaltechAUTHORS:20230203-893210800.24

Funding

NASA
80NSSC19K1020
Alexander von Humboldt Foundation
NASA
80GSFC21M0002
NASA
80NSSC19K1023
NASA
NNH18ZDA001N

Dates

Created
2023-02-24
Created from EPrint's datestamp field
Updated
2023-02-24
Created from EPrint's last_modified field

Caltech Custom Metadata

Caltech groups
Space Radiation Laboratory , NuSTAR