Hard X-Ray flux upper limits of central compact objects in supernova remnants

We searched for hard X-ray (20–300 keV) emission from nine central compact objects (CCOs) 1E 1207.4−5209, 1WGA J1713−3949, J082157.5−430017, J085201.4−461753, J1601−5133, J1613483−5055, J181852.0−150213, J185238.6+004020, and J232327.9+584843 with the INTEGRAL observatory. We applied spectral imaging analysis and did not detect any of the sources with luminosity upper limits in the range of 1033-1034 ergs/s in the 20-75 keV band. For nearby CCOs (< 4 kpc) the upper limit luminosities are an order of magnitude lower than the measured persistent hard X-ray luminosities of AXPs. This may indicate that the central compact objects are low magnetic field systems with fallback disks around them.