The search for signatures of cosmic bullets

摘要

Since its launch in 1999, the European X-ray observatory XMM-Newton has suffered, 4 times, possible micro-meteoroid impacts believed to occur in the mirror shells, scattering debris toward the focal plane. The latest event, on 2005 March 09th, caused the loss of EPIC MOS1 CCD6, as well as small damage to MOS1 CCD1. This latter defect is leaking into the whole column that passes a few pixels from the nominal target position on CCD1 and affects a significant fraction of the on-axis source PSF (though the effects can be mitigated by suitable on-board offsetting of the signal from that column). We report on our investigations looking for possible pinholes in the XMM-Newton EPIC MOS1 filter created by micro-meteoroid generated debris. New simulation code allows modelling of pinhole patterns in real data sets. We will show the comparison between simulations and specially performed in-orbit detection measurements. These allow us to define the limiting size above which pinholes can be detected and to show if XMM-Newton's filters have suffered significantly from the micro-meteoroids.