[SN, SNR, and Isolated NS -- Oral ]
New Deep X-ray and Radio Observations of G1.9+0.3
Kazimierz Borkowski, North Carolina State University
S.P.Reynolds (NCSU), D.A.Green (University of Cambridge), U.Hwang, I.Harrus, R.Petre (NASA/GSFC)
{\it Chandra} X-ray observations revealed G1.9+0.3 to be the
youngest known Galactic supernova remnant (SNR), only $\sim 100$ yr old.
Subsequent observations with the Very Large Array (VLA) confirmed this
discovery. Both X-ray and radio emission are produced by relativistic
electrons, accelerated in shocks with extreme (up to 14,000 km s$\^{-1}$)
velocities, but their morphologies are strikingly different. A pronounced
NE--SW radio asymmetry contrasts with a bipolar NW--SE X-ray emission
that arises in shocks capable of accelerating electrons to $\sim 10-100$
TeV energies. Harder X-rays correlate with systematically varying X-ray
brightness along the remnant's periphery. This may be interpreted in
terms of the magnetic field obliquity dependence of the cosmic-ray
acceleration efficiency, but observations available until now have not
allowed for distinguishing between models with radically different field
geometries. These models also fail to explain the strong NE--SW radio
asymmetry. We present new deep {\it Chandra} and VLA observations that
allow us to examine spatial morphologies and spectra of G1.9+0.3 in much
greater detail than previously possible. We discuss how these observations
advance our knowledge of particle acceleration in very fast SNR shocks.