2. 1st INTEGRAL Data Analysis Workshop ISDC, October 5-8, 2004 Imaging extended sources with JEM-X
N. Lund
C. Budtz-Jorgensen
N.J. Westergaard
J. Chevenez
Danish Space
Research Institute

3. Imaging of extended sources with a coded mask instrument
Coded mask instruments are good for point sources because the point spread function is simple and the source signal is concentrated in a few pixels of the image.
It is therefore also relatively simple to estimate the background under the source.
Imaging extended sources are more complex – particularly if the morphology of the source is to be studied without prejudices.
The results obtained in an analysis of a 1 Msec observation of SN1006 have demonstrated that JEM-X can image an extended source, and have inspired us to look at other data which have become public lately.

4. Imaging of extended sources by JEM-X Case I: SN 1006
SN 1006 is an X-ray bright, high-latitude supernova remnant, well studied in many wavelengths. Significant cosmic ray accelleration is expected to take place in the remnant. INTEGRAL has observed SN 1006 for 1 Msec (PI: Steven Reynolds)
Shown here is an ASCA (0.4-8 keV) image of the remnant showing two X-ray emission lobes concentrated in the regions of strong electron accelleration near the remnnant boundary.

5. JEM-X images of SN 1006 ASCA 0.4-8 keV JEM-X 3-4 keV JEM-X 4-8 keV
At energies above 8 keV we cannot yet reliably detect the source We are working on reducing the background noise in our images. Only 75% of the available INTEGRAL data have been used up to now.

6. JEM-X imaging of extended sources Case II: Coma cluster
3 to 4 keV to 8 keV
The cluster is not securely detected above 8 keV.

7. JEM-X imaging of extended sources Case III: NGC 1275
Central radio jet Radio halo Optical filaments (H-alpha) keV X-rays arcsec arcmin arcmin arcmin N-S aligned N-S aligned N-S aligned ? symmetric

8. JEM-X images of NGC 1275
3-4 keV keV
The N-S alignment of the core jet of NGC 1275 apparently emerges again in hard X-rays
JEM-X point spread function illustrated with an image of GRS
8-14 keV keV

9. Extended source caveats
1) The outer extensions of the JEM-X image of the X-ray halo of NGC 1275 do not match with the XMM image.
(Inadequate flat fielding of JEM-X image?)
White contours: XMM 2 to 7 keV
Green contours: JEM-X 4 to 8 keV
2) The observation was disturbed by a varying background. More work is needed!
3) Be patient !

10. Midisky background suppression experiments
Local flat field
No cleaning
Global flat field

11. Detection of faint sources by JEM-X
The OSA 4.0 supplied image mosaicking tool does not work with the JEM-X images generated under OSA 4.0
An improved imaging software (Midisky) is available from DSRI together with a mosaicking tool (Mosaic_weight). Both of these packages can be downloaded via ftp from:
DSRI.DK pub/jemx/mosaic_weight.tar.gz
pub/jemx/midisky/midi_distribution_2.tar.gz
Both packages will become part of the OSA 5.0.

12. Galactic Center GCDE

13. Galactic Center SgrA
PI: A. Goldwurm