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The SED from an AGN discovered by AKARI. The blue and square mark data are obtained by AKARI instrument. The triangle and '+' mark are data from IRAS and 2MASS, respectively. The solid line shows a SED model for a nearby star-burst galaxy M82. Compared to the model, the AKARI spectrum shows an excess, suggesting hot dust or AGN in the source.

New Objects Discovered with AKARI All Sky Survey

In 22 February 2009, the Japanese infrared satellite AKARI became three years old. We also had the first international conference in 16 - 19 February at the University of Tokyo in Hongo. We had more than 140 participants, and half of them who are using AKARI data came from the outside of Japan. Many researchers gave their result to each other and it was very successful conference. We are happy with these days somehow.

Even thought AKARI has a function to make pointed observations toward interesting targets, the main purpose of AKARI was to make the infrared map of all sky in the mid- and far-infrared. In the first one and half years (we call it Phase 1 & 2) when AKARI had the liquid helium in the cryostat, we carried out all sky survey. In order to release source catalogs to astronomers all over the world, we are making them. At the present time, the infrared catalogs that the previous infrared surveyor IRAS made in 25 years ago was used by many astronomers. Therefore, we can expect that many astronomers are looking forward to the AKARI catalogs. In order to make good catalogs which are expected of them, we are working hard right now.

Although we will provide good catalogs to astronomers all over the world, we are going to use them for ourselves. In fact, we started new projects of AKARI follow-ups whose targets come from AKARI mid-infrared all sky survey. We selected 9 micron-excess sources comparing them with Ks-band fluxes in Two Micron All Sky Survey (2MASS). Using the near-infrared spectroscopy function which is presently working after the liquid helium runs out (we call this term Phase 3), we are taking 2.5-5.0 micron spectra of 9 micron-excess sources in one of AKARI Mission Programs. These spectra provide the information about the reason for their 9 micron-excess.

Our purpose of this observation is to find Active Galactic Nuclei (AGNs). AGNs have a central engine surrounded by hot dust that emit strongly in the near- and mid-infrared. Because observing them in the near- and mid-infrared has advantage of small extinction, our survey has a capability to detect not only normal AGNs, but also dusty AGNs that are missed by optical and X-ray surveys. We have just started the follow-up observations, and have succeeded in detecting AGNs in our sample. Some of them are not known as AGNs, then they do not have any name before. In order to estimate the total density of AGNs, we will continue the observations.

We have just started to deliver AKARI data in Phase 3 from DARTS.

Shinki Oyabu ( Department of Infrared Astrophysics/ISAS )

March 2009