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

Abstract

NuSTAR observed G1.9+0.3, the youngest known supernova remnant in the Milky Way, for 350 ks and detected emission up to $\sim$30 keV. The remnant's X-ray morphology does not change significantly across the energy range from 3 to 20 keV. A combined fit between NuSTAR and CHANDRA shows that the spectrum steepens with energy. The spectral shape can be well fitted with synchrotron emission from a power-law electron energy distribution with an exponential cutoff with no additional features. It can also be described by a purely phenomenological model such as a broken power-law or a power-law with an exponential cutoff, though these descriptions lack physical motivation. Using a fixed radio flux at 1 GHz of 1.17 Jy for the synchrotron model, we get a column density of N${}_{\mathrm{H}}$ = $(7.23\pm 0.07)\times 10^{22}$ cm${}^{-2}$, a spectral index of $\alpha =0.633\pm 0.003$, and a roll-off frequency of ${\nu }_{\mathrm{rolloff}}=(3.07\pm 0.18)\times 10^{17}$ 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 $\mu$G, 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 $1.5\times 10^{-5}$ $\mathrm{ph}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ assuming a line width of 4.0 keV (1 sigma).

9 pages, 6 figures, accepted ApJ

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Cited by in corpus (7)

• Asymmetric Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3
• ${}^{44}\mathrm{Ti}$ ejecta in young supernova remnants
• A Complete Catalogue of Dusty Supernova Remnants
• Modeling SNR G1.9+0.3 as a Supernova Inside a Planetary Nebula
• NuSTAR observations of the supernova remnant RX J1713.7$-$3946
• Presolar grains
• Search for the time evolution of the synchrotron X-ray spectrum of the youngest Galactic supernova remnant G1.9+0.3 using Suzaku