XMM-Newton exposure-corrected mosaic images of SNR W44 region in hard (4.0–8.0 keV) X-ray bands. Left: FoV of W44 with the SNR radio contours in yellow (radio fits file obtained from SNRC at http://snrcat.physics.umanitoba.ca/SNRrecord.php?id=G034.7m00.4) and the soft (0.5–4.0 keV) X-ray contour of W44 in cyan. The position of PSR B1853+01 is marked by a black cross with a green arrow indicating the direction of the pulsar’s proper motion inferred from the pulsar’s position relative to the SNR center and the axis of symmetry of the PWN. Right: Extended X-ray emission coinciding with the position of PSR B1853+01 inside W44. The position of PSR B1853+01 is marked by a black cross. The inner part of the dashed white lines corresponds to the PWN surrounding PSR B1853+01, while the faint extended emission surrounding the PWN is a possible X-ray “halo”. Note that the edge of the thermal emission from SNR cut the halo into two parts.