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Published January 10, 2015 | Published + Submitted
Journal Article Open

The Hard X-Ray View of the Young Supernova Remnant G1.9+0.3


NuSTAR observed G1.9+0.3, the youngest known supernova remnant in the Milky Way, for 350 ks and detected emission up to ~30 keV. The remnant's X-ray morphology does not change significantly across the energy range from 3 to 20 keV. A combined fit between NuSTAR and Chandra shows that the spectrum steepens with energy. The spectral shape can be well fitted with synchrotron emission from a power-law electron energy distribution with an exponential cutoff with no additional features. It can also be described by a purely phenomenological model such as a broken power law or a power law with an exponential cutoff, though these descriptions lack physical motivation. Using a fixed radio flux at 1 GHz of 1.17 Jy for the synchrotron model, we get a column density of N_H = (7.23 ± 0.07) × 10^(22) cm^(–2), a spectral index of α = 0.633 ± 0.003, and a roll-off frequency of ν_(rolloff) = (3.07 ± 0.18) × 10^(17) Hz. This can be explained by particle acceleration, to a maximum energy set by the finite remnant age, in a magnetic field of about 10 μG, for which our roll-off implies a maximum energy of about 100 TeV for both electrons and ions. Much higher magnetic-field strengths would produce an electron spectrum that was cut off by radiative losses, giving a much higher roll-off frequency that is independent of magnetic-field strength. In this case, ions could be accelerated to much higher energies. A search for ^(44)Ti emission in the 67.9 keV line results in an upper limit of 1.5 × 10^(–5) photons cm^(–2) s^(–1) assuming a line width of 4.0 keV (1 sigma).

Additional Information

© 2015 American Astronomical Society. Received 2014 September 29; accepted 2014 October 29; published 2014 December 31. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. 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 (Caltech, USA). Facilities: NuSTAR, CXO

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Published - 0004-637X_798_2_98.pdf

Submitted - 1411.6752v1.pdf


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August 22, 2023
August 22, 2023