  Magnetic fields have been measured around Asymptotic Giant Branch (AGB) stars
of all chemical types using maser polarization observations. If present, a
large-scale magnetic field would lead to X-ray emission, which should be
observable using current X-ray observatories. The aim of this work is to search
the archival data for AGB stars that are intrinsic X-ray emitters. We have
searched the ROSAT, CXO, and XMM archives for serendipitous X-ray observations
of a sample of ~500 AGB stars. We specifically searched for the AGB stars
detected with GALEX. The data is calibrated, analyzed and the X-ray
luminosities and temperatures are estimated as functions of the circumstellar
absorption. We identify 13 AGB stars as having either serendipitous or targeted
observations in the X-ray data archives, however for a majority of the sources
the detailed analysis show that the detections are questionable. Two new
sources are detected by ROSAT: T Dra and R UMa. The spectral analysis suggests
that the emission associated with these sources could be due to coronal
activity or interaction across a binary system. Further observations of the
detected sources are necessary to clearly determine the origin of the X-ray
emission. Moreover, additional objects should be subject to targeted X-ray
observations in order to achieve better constraints for the magnetic fields
around AGB stars.
