We carry out a study of Sub-Millimeter Galaxies (SMGs) in the AKARI NEP-Deep field using the James Clerk Maxwell Telescope (JCMT) SCUBA-2 850 μm source catalog, released as part of the SCUBA-2 Cosmology Legacy Survey (S2CLS) program. The SCUBA-2 850 μm map has a root mean square (rms) noise of 1.2 mJy beam−1 and covers an area of 0.60 degree2. We find four SMGs which have counterparts to Herschel sources with spectroscopic redshifts in the literature. In addition, three dust obscured galaxies (DOGs) detected in Herschel bands are selected as a comparison sample. We derive IR luminosities of SMGs using the CIGALE code, which are similar to those of high redshift SMGs from previous studies. The contribution of AGN to the total IR luminosity in SMGs (2%–11%) is smaller than the lower limit for the one in DOGs (19%–35%), which is consistent with the expectation from the evolutionary scenario of massive galaxies. We search for SMGs in overdense regions as protocluster candidates and investigate four regions, including candidates around three DOGs. Finally, we argue that follow-up spectroscopic observation for the NEP-Deep field will provide crucial information to understand the role of SMGs in the evolution of massive galaxies.

The extragalactic background suggests half the energy generated by stars was reprocessed into the infrared (IR) by dust. At z1.3, 90% of star formation is obscured by dust. To fully understand the cosmic star formation history, it is critical to investigate infrared emission. AKARI has made deep mid-IR observation using its continuous 9-band filters in the NEP field (5.4 deg2), using 10% of the entire pointed observations available throughout its lifetime. However, there remain 11,000 AKARI infrared sources undetected with the previous CFHT/Megacam imaging (r ~25.9ABmag). Redshift and IR luminosity of these sources are unknown. These sources may contribute signicantly to the cosmic star-formation rate density (CSFRD). For example, if they all lie at 1< z <2, the CSFRD will be twice as high at the epoch. We are carrying out deep imaging of the NEP eld in 5 broad bands (g; r; i; z; and y) using Hyper Suprime-Camera (HSC), which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric redshift information, and thereby IR luminosity for the previously-undetected 11,000 faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid- IR luminosity measurement, this will allow a complete census of cosmic star-formation/AGN accretion history obscured by dust.

There exists strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. An important mechanism connecting AGN to their host galaxies is AGN feedback, potentially heating up or even expelling gas from galaxies. AGN feedback may hence be responsible for the eventual quenching of star formation and halting of galaxy growth. A rich multi- wavelength dataset ranging from the X-ray regime (Chandra), to far-IR (Herschel), and radio (WSRT) is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope, covering a total area on the sky of 5.4 sq. degrees. We investigate the star formation properties and possible signatures of radio feedback mechanisms in the host galaxies of 237 radio sources below redshift z = 2 and at a radio 1.4 GHz ux density limit of 0.1 mJy. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied simultaneously as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this eld, while also offering evidence showcasing a link between AGN activity and host galaxy star formation. In particular, we show results supporting a maintenance type of feedback from powerful radio-jets.