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 Research No.1


Dramatic improvement in accuracy and spatial resolution of all sky dust map: the all sky Galactic dust emission observed with the Japanese Infrared Astronomical Satellite AKARI.


Weak Diffuse Lights Widely Spread in the Universe

  You are probably busy everyday with work or school, not having time to look up the night sky. When the sun goes down, what do you see when you look up the sky? Unless living in the urban area, you have probably spotted with your own eyes the Milky Way or some stars glow. What you can see with your naked eyes are mostly stars and galaxies. Now, are they really only stars and galaxies glowing in the universe? Have you ever seen the thermographic images? You might have seen the images to monitor the human body temperature. This image is different from what we see with human eyes and is to measure the temperature. If we can see the objects through infrared rays, why not exploit this for observations of the universe. Even astronomers are leaving nothing to chance, the Infrared Astronomical Satellite (IRAS) was launched in 1983 as a joint project of the United States, the United Kingdom and the Netherlands.

  The satellite conducted the all-sky survey observations. When IRAS actually observed, they discovered the universe in the infrared images containing not only the stars or galaxies, but also the dust emissions widely fulfilling the sky. In 2006, AKARI (the Japanese infrared astronomical satellite) was also launched to survey the entire sky in the infrared domain for one and a half year.

  I have been involved with this “AKARI” project from before its launch for over 10 years. Intensified with Japanese technology, “AKARI” enabled us to conduct the all-sky survey in the space with much sufficient spatial resolution than IRAS’s. The emission from the dust within the solar system is very bright in mid-infrared wavelength (7-25 micrometers), whereas the Galactic dust is the dominant source in far-infrared region (50-180 micrometers). The data acquired with “AKARI” is making clear the spatial distribution of dust grains. This survey data is not only important to clarify the current figure of the solar system and the galaxy. In order to capture, correctly, further weak lights of the beginning of the universe traveled from far away distant, the accurate distribution map of the Galactic infrared emission becomes inevitable. The all sky dust distribution map using far-infrared all sky data obtained with the IRAS was analyzed and created by the mapping team centered by Dr. Finkbeiner (Harvard University), which has been widely used all over the world. I would like to try to create the Galactic dust map in much more details by using data obtained with Japan’s proud infrared satellite AKARI, together with Dr. Hattori, Dr. Doi, and Dr. Morishima. For achieving this, I would like to make several visits to Harvard University during the Brain Circulation Program to team up and carry out collaborative work with Dr. Finkbeiner.

  The state-of-the-art map-making will go on exhibiting how the weak diffuse lights emitted from the dust spread over the universe.

Tohoku University, Graduate School of Science, Astronomical Institute
Dr. Takafumi Otsubo, an Associate Professor


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