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A debris disk around an isolated young neutron star


Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star1 or it may possess sufficient angular momentum to form a disk2. Such ‘fallback’ is both a general prediction of current supernova models3 and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation4. Fallback disks could dramatically affect the early evolution of pulsars2,5, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (≥ 106 years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars6, suggesting the possibility of planet formation around young neutron stars.

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We thank M. van Kerkwijk for sharing the Ks-band image of 4U 0142 + 61. We also thank A. Alpar, L. Bildsten, E. Chiang, M. Durant, E. Dwek, Y. Ekşi, L. Hernquist, M. Jura and R. Narayan for discussions. This work is based on observations made with the Spitzer Space Telescope, which is operated by JPL/Caltech under a NASA contract. Support for this work was provided by NASA through a contract issued by JPL/Caltech. DLK was supported by a Pappalardo Fellowship.

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Correspondence to Deepto Chakrabarty.

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Figure 1: Infrared images of the 4U 0142 + 61 field.
Figure 2: Infrared colour–colour diagram for 4U 0142 + 61 (diamond) and 33 field stars (small crosses) from the 2MASS point source catalogue.
Figure 3: Optical/infrared spectral energy distribution of 4U 0142 + 61.


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