High-energy X-ray imaging of the pulsar wind nebula MSH 15–52: constraints on particle acceleration and transport
- Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
- Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
- Physics Department, NC State University, Raleigh, NC 27695 (United States)
- Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
- DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
- CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
- Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
- Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
We present the first images of the pulsar wind nebula (PWN) MSH 15–52 in the hard X-ray band (≳8 keV), as measured with the Nuclear Spectroscopic Telescope Array (NuSTAR). Overall, the morphology of the PWN as measured by NuSTAR in the 3-7 keV band is similar to that seen in Chandra high-resolution imaging. However, the spatial extent decreases with energy, which we attribute to synchrotron energy losses as the particles move away from the shock. The hard-band maps show a relative deficit of counts in the northern region toward the RCW 89 thermal remnant, with significant asymmetry. We find that the integrated PWN spectra measured with NuSTAR and Chandra suggest that there is a spectral break at 6 keV, which may be explained by a break in the synchrotron-emitting electron distribution at ∼200 TeV and/or imperfect cross calibration. We also measure spatially resolved spectra, showing that the spectrum of the PWN softens away from the central pulsar B1509–58, and that there exists a roughly sinusoidal variation of spectral hardness in the azimuthal direction. We discuss the results using particle flow models. We find non-monotonic structure in the variation with distance of spectral hardness within 50'' of the pulsar moving in the jet direction, which may imply particle and magnetic-field compression by magnetic hoop stress as previously suggested for this source. We also present two-dimensional maps of spectral parameters and find an interesting shell-like structure in the N {sub H} map. We discuss possible origins of the shell-like structure and their implications.
- OSTI ID:
- 22370584
- Journal Information:
- Astrophysical Journal, Vol. 793, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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