New constraints on the cosmic mid-infrared background using TeV gamma-ray astronomy

Very high energy gamma-ray data obtained by CAT and HEGRA from the active g alactic nucleus Mkn 501 are used to constrain the cosmic Mid-Infrared backg round. While the entire infrared and submillimeter spectrum shape based on models has been fixed and the density scaled as a whole in previous studies , recent measures on the low and high energy infrared background are extens ively used in this paper. In this original approach the infrared distributi on is only varied in the unexplored 3.5-100 mum region. With a conservative hypothesis on the intrinsic spectrum of Mkn 501, an upper limit of 4.7 nW m(-2) sr(-1) between 5 and 15 mum is derived, which is very close to the lo wer limit inferred from deep ISOCAM cosmological surveys at 15 mum. This re sult is shown to be independent of the exact density of the lambda <3.5 <mu >m and lambda >100 mum infrared distribution within the uncertainties of th e measurements. Moreover, the study presented here rules out a complete ext ragalactic origin for the 60 micron tentative background detection as found by Finkbeiner et al. (2000).