2006ApJ...649L.107K

We present evidence for excess long-wavelength emission from two high-mass X-ray binaries, IGR J16318-4848 and GX 301-2, that show enormous obscuration (N_H≃10²³-10²⁴/cm2) in their X-ray spectra. Using archival near- and mid-infrared data, we show that the spectral energy distributions of IGR J16318-4848 and GX 301-2 are substantially higher in the mid-infrared than their expected stellar emission. We successfully fit the excesses with ∼1000 K blackbodies, which suggests that they are due to warm circumstellar dust that also gives rise to the X-ray absorption. However, we need further observations to constrain the detailed properties of the excesses. This discovery highlights the importance of mid-infrared observations for understanding highly obscured X-ray binaries.