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Title: 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 {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 formore » 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)« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ; ; ;  [6] ;  [7] ;  [8] ;  [9]
  1. Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
  2. Physics Department, North Carolina State University, Raleigh, NC 27695 (United States)
  3. Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada)
  4. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)
  5. CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
  6. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  7. Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States)
  8. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
  9. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22364650
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 798; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ELECTRON SPECTRA; ENERGY SPECTRA; GHZ RANGE; HARD X RADIATION; INDEXES; KEV RANGE; LINE WIDTHS; MAGNETIC FIELDS; MILKY WAY; PHOTON EMISSION; SUPERNOVA REMNANTS; TEV RANGE; TITANIUM 44