Stephen P. Reynolds et al 2009 ApJ 695 L149 doi:10.1088/0004-637X/695/2/L149
Stephen P. Reynolds1, Kazimierz J. Borkowski1, David A. Green2, Una Hwang3, Ilana Harrus3 and Robert Petre3
Show affiliationsThe discovery of the youngest Galactic supernova remnant (SNR) G1.9+0.3 has allowed a look at a stage of SNR evolution never before observed. We analyze the 50 ks Chandra observation with particular regard to spectral variations. The very high column density (NH ~ 6 × 1022 cm–2) implies that dust scattering is important, and we use a simple scattering model in our spectral analysis. The integrated X-ray spectrum of G1.9+0.3 is well described by synchrotron emission from a power-law electron distribution with an exponential cutoff. Using our measured radio flux and including scattering effects, we find a rolloff frequency of 5.4(3.0, 10.2) × 1017 Hz (hνroll = 2.2 keV). Including scattering in a two-region model gives lower values of νroll by over a factor of 2. Dividing G1.9+0.3 into six regions, we find a systematic pattern in which spectra are hardest (highest νroll) in the bright southeast and northwest limbs of the shell. They steepen as one moves around the shell or into the interior. The extensions beyond the bright parts of the shell have the hardest spectra of all. We interpret the results in terms of dependence of shock acceleration properties on the obliquity angle θBn between the shock velocity and a fairly uniform upstream magnetic field. This interpretation probably requires a Type Ia event. If electron acceleration is limited by synchrotron losses, the spectral variations require obliquity-dependence of the acceleration rate independent of the magnetic-field strength.
98.62.En Electric and magnetic fields
98.62.Ai Origin, formation, evolution, age, and star formation
Issue 2 (2009 April 20)
Received 2008 December 23, accepted for publication 2009 March 10
Published 2009 March 30
Stephen P. Reynolds et al 2009 ApJ 695 L149
The H1 and ZEUS collaborations JHEP10(2009)013
ZEUS collaboration JHEP08(2009)077
ZEUS Collaboration JHEP04(2009)082
ZEUS collaboration JHEP12(2009)007
Ramon Ferrer i Cancho and Albert Díaz-Guilera J. Stat. Mech. (2007) P06009
Y Censor et al 1988 Inverse Problems 4 607
Yunping Jiang and David Ruelle 2005 Nonlinearity 18 2447
Gregory Falkovich 2009 J. Phys. A: Math. Theor. 42 123001
Yousef I Salamin 2006 New J. Phys. 8 133