Is the infrared background excess explained by the isotropic zodiacal light from the outer solar system?

This paper investigates whether an isotropic zodiacal light from the outer solar system can account for the detected background excess in the near-infrared. Assuming that interplanetary dust particles are distributed in a thin spherical shell at the outer solar system (>200 au), thermal emission from such cold (<30 K) dust in the shell has a peak at the far-infrared (similar to 100 mu m). By comparing the calculated thermal emission from the dust shell with the observed background emissions at the far-infrared, the permissible dust amount in the outer solar system is obtained. Even if the maximum dust amount is assumed, the isotropic zodiacal light as the reflected sunlight from the dust shell at the outer solar system cannot explain the detected background excess at the near-infrared.