The compact X-ray source 1E 1547.0-5408 and the radio shell G327.24-0.13: a new proposed association between a candidate magnetar and a candidate supernova remnant.
GELFAND J.D. and GAENSLER B.M.
Abstract (from CDS):
We present new observations of the field centered on X-ray source 1E 1547.0-5408. Analysis of a new Chandra observation shows that it is unresolved at arcsecond resolution, and analysis of a new XMM-Newton observation shows that its X-ray spectrum is best described by an absorbed power-law and blackbody model. A comparison of the X-ray flux observed from 1E 1547.0-5408 between 1980 and 2006 reveals that its absorbed 0.5-10 keV X-ray flux decreased from ∼2x10–12 to ∼3x10–13 ergs/cm2 during this period. The most recent XMM-Newton observation detected no pulsations from 1E 1547.0-5408, allowing us to put a 5 σ confidence upper limit of 14% for the 0.5-10 keV peak-to-peak pulsed fraction for sinusoidal pulses with periods slower than 1.8 s. A near-infrared observation shows a magnitude Ks=15.9±0.2 source near 1E 1547.0-5408, but the implied X-ray to infrared flux ratio indicates that it is an unrelated field source, limiting the IR magnitude of any counterpart to 1E 1547.0-5408 to ≳17.5. Archival radio observations reveal that 1E 1547.0-5408 sits at the center of a faint, small radio shell, G327.24-0.13, possibly a previously unidentified supernova remnant. The X-ray properties of 1E 1547.0-5408 suggest that it is a magnetar, and the spatial coincidence between this source and G327.24-0.13 suggests that 1E 1547.0-5408 is associated with a young supernova remnant, supporting a neutron star interpretation. If both the nature of 1E 1547.0-5408 and G327.24-0.13 and their physical association are confirmed, this pair will be an important addition to the small number of known associations between magnetars and supernova remnants.