An
INTEGRAL
View of
γ-Cygni SNR
For the first time a supernova remnant has been spatially resolved in hard X-rays.
What follows is just a brief summary, but see the regular article
in Astronomy and Astrophysics
(
A&A, v.427, p. L21 )
or in the arXiv (astro/ph 0410688)
for a complete review.
Spatially resolved images of the galactic supernova
remnant
G78.2+2.1
(γ-Cygni) in hard X-ray energy bands from
25 keV to 120 keV are obtained with the
IBIS-ISGRI
imager aboard the International Gamma-Ray Astrophysics Laboratory
INTEGRAL
.
The images are dominated by localized clumps of about
ten arcmin in size. The flux of the most prominent North-Western
(NW) clump is (1.7±0.4)×10-11
erg cm-2 s-1 in the 25-40
keV band. The observed X-ray fluxes are in agreement with
extrapolations of soft X-ray imaging observations of γ-Cygni
by
ASCA GIS
and spatially unresolved
RXTE PCA
data. The positions of the hard X-ray clumps correlate with bright patches
of optical line emission, possibly indicating the presence of
radiative shock waves in a shocked cloud. The observed spatial
structure and spectra are consistent with model predictions of
hard X-ray emission from nonthermal electrons accelerated by a
radiative shock in a supernova interacting with an interstellar
cloud, but the powerful stellar wind of the O9V star
HD 193322
is a plausible candidate for the NW source as well.
Left: ASCA GIS 6-10 keV grayscale map with an INTEGRAL ISGRI
25-40 keV 4.2 σ contour in the NW area.
Centre: ROSAT PSPC-B 0.4-2.0 keV grayscale map with the same
INTEGRAL ISGRI 25-40 keV 4.2 σ contour.
Right: INTEGRAL ISGRI 25-40 keV significance map (linear scale) with
Hα+[NII] 6560 Å
3×10-15 erg cm-2 s-1 arcsec-1
contours (dotted line)
and [OIII] 5010 Å
3×10-16 erg cm-2 s-1 arcsec-1
contours (solid line) [optical data are from
Mavromatakis (2003)
].
The hard emission regions NW, NE, and SE are marked in the first two panels.
The NE clump is seen with ISGRI only in the 40-80 keV band.
The RXTE PCA field of view is indicated by the large solid circle. The black cross on the ROSAT
map marks the position of the O9V star
HD 193322 (20:18:07,+40:43:55). All the maps are made for J2000.
The spectral energy distribution of the hard emission
from γ-Cygni. The ISGRI datapoints correspond to the NW clump
only.
