The First Source Counts at 18 μm from the AKARI NEP Survey

摘要: We present the first galaxy counts at 18 μm using Japanese AKARI satellite's survey North Ecliptic Pole (NEP), produced from images NEP-Deep and NEP-Wide surveys covering 0.6 5.8 deg 2 , respectively. describe a procedure point source filtering algorithm to remove background structure minimum variance method for our extraction photometry that delivers optimum signal noise extracted sources, confirming this by comparison with standard methods. The final are complete reliable over three orders of magnitude in flux density, resulting sensitivities (80 per cent completeness) 0.15 0.3 mJy surveys, respectively, factor 1.3 deeper than previous catalogues constructed field. differential exhibit characteristic upturn Euclidean expectations around milliJansky corresponding evolutionary bump between 0.2–0.4 consistent mid-infrared ISO Spitzer 15 24 μm. compare results evolution models striking divergence non-evolving scenario. observations broad agreement implying strongly evolving population luminous infrared galaxies redshifts higher unity. Integrating down limit NEP 150 μJy level we calculate has resolved approximately 55 cosmic relative predictions contemporary count models.