THE HARD X-RAY VIEW OF THE YOUNG SUPERNOVA REMNANT G1.9+0.3
- Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
- Physics Department, North Carolina State University, Raleigh, NC 27695 (United States)
- Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
- 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)
- Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (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)
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 {sub H} = (7.23 ± 0.07) × 10{sup 22} cm{sup –2}, a spectral index of α = 0.633 ± 0.003, and a roll-off frequency of ν{sub rolloff} = (3.07 ± 0.18) × 10{sup 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 {sup 44}Ti emission in the 67.9 keV line results in an upper limit of 1.5 × 10{sup –5} photons cm{sup –2} s{sup –1} assuming a line width of 4.0 keV (1 sigma)
- OSTI ID:
- 22364650
- Journal Information:
- Astrophysical Journal, Vol. 798, 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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