We report the discovery of X-ray polarization from the X-ray-bright filament.
G0.13-0.11 in the Galactic center (GC) region. This filament features a bright,
hard X-ray source that is most plausibly a pulsar wind nebula (PWN) and an
extended and structured diffuse component. Combining the polarization signal
from IXPE with the imaging/spectroscopic data from Chandra, we find that X-ray
emission of G0.13-0.11 is highly polarized PD=57(±18)
while the polarization angle is PA=21^∘(±9^∘). This high degree of
polarization proves the synchrotron origin of the X-ray emission from
G0.13-0.11. In turn, the measured polarization angle implies that the X-ray
emission is polarized approximately perpendicular to a sequence of nonthermal
radio filaments that may be part of the GC Radio Arc. The magnetic field on the
order of 100 μ G appears to be preferentially ordered along the
filaments. The above field strength is the fiducial value that makes our model
self-consistent, while the other conclusions are largely model independent.
