Spitzer Space Telescope - Directors Discretionary Time Proposal #287

Spitzer DDT observations of  the anomalous X-ray pulsar 4U 0142+61 

Principal Investigator: Zhongxiang Wang
Institution: McGill  

Science Category: Circumstellar/Debris Disks
Observing Modes: IRAC Mapping 
Hours Approved: 1.7

Abstract:

Previous Spitzer/IRAC observations have discovered the mid-IR
counterpart to anomalous X-ray pulsar (AXP) 4U 0142+61.  The discovery
may indicate the first detection of a fallback disk around a young,
isolated neutron star. The putative disk likely formed from fallback
material in the supernova explosion that produced the neutron star.  The
disk is likely bright in the mid-IR due to irradiation by the strong
X-rays from the pulsar.  At 10:04:19 UTC on 7 February 2007, the AXP
exhibited a large fast-rise X-ray burst, with the peak X-ray flux being
more than 100 times higher than its quiescent X-ray flux.  Here we
request Spitzer/IRAC observations of the source. Combining them with our
scheduled Chandra ToO X-ray observations of the source, we will be able
to test the disk model by searching for correlated mid-IR/X-ray flux
changes.  If correlated flux changes are found, the observations would
allow us to further study the properties of the disk.