1.What's SUBARUH

SUBARU is the 8.3 meter optical-infrared telescope at the summit of Mauna Kea in Hawaii that is being built by The National Astronomical Observatory(NAOJ).
If the construction is finished, it must become the best and largest telescope in Japan.

It is very difficult to build an over 8 meter telescope, because its large mirror is distorted by the force of gravity.

SUBARU avoids this problem by using many control devices. They always keep the main mirror suitable. (Fig1:The picture of SUBARU)

2.Significance of observing gamma-ray with SUBARU

SUBARU is the telescope for observing visible and infrared region.

Light is classified by its energy.
Energy of the visible and infrared light is under 10 eV. On the other hand, we are interested in the light that has the energy higher than 1MeV (1MeV = 1000000eV;Generally speaking it is gamma-ray). Especially in this project, we try to observe much higher energy light, tens of Gev(1GeV = 1000MeV). This energy is 10^9 times higher than that of visible light that is main target of SUBARU.

Then, why do we want to observe gamma-ray using SUBARU?

Main reason of it is that "We've never observe the region of tens GeV". According to the recent research,many Pulsers and AGNs (Active Galactic Nucleus)have a cut-off at over tens of GeV on their energy spectrum(Fig2:Pulse Cut-off). So,the detailed observation in this reason is useful for understanding the mechanism of accelerating particles. However, it is hard to observe tens of GeV reason. Satellites in the space can't catch tens of GeV gamma-ray because of decreasing of flux(Satellites are good at under 1Gev).Cherencov telescopes on the ground also can't catch because of decreasing of intensity(Cherenkov telescope is good at over 100GeV).

Only one method to catch tens of GeV gammma-ray is to build the telescope that has very large mirror (about 10 m) on the top of the very high mountain (about 4000 m).According to our simulation, on the top of 4000m mountain, light intensity is 4 times higher than that of the ground. Of cause, Large mirror is very useful for gathering photons. It is true we can't afford to built such a telescope, but SUBARU is ideal telescope that can meet above conditions and it has already done first-light!

Now, we are tackling to build gamma-ray camera for SUBARU.

Sorry, this page is under construction.....:-)


Question is here.(Hiro Asahara)