The nearby (d = 19.7 Mpc) Seyfert galaxy NGC 3079 exhibits a prominent bubble emerging from the nucleus. In order to investigate the nuclear power source, we carried out ammonia observations toward the center of NGC 3079 with the Tsukuba 32-m telescope and the JVLA. The NH3 (J,K) = (1, 1) through (6, 6) lines were detected in absorption at the center of NGC 3079 with the JVLA, although the profile of NH3 (3, 3) was in emission in contrast to the other transitions. All ammonia absorption lines have two distinct velocity components: one is at the systemic velocity (Vsys ~ 1116 km s−1) and the other is blueshifted (Vsys ~ 1020 km s−1), and both components are aligned along the nuclear jets. The blueshifted NH3 (3, 3) emission can be regarded as ammonia masers associated with shocks by strong winds probably from newly formed massive stars or supernova explosions in the nuclear megamaser disk. The derived rotational temperature, Trot = 120 ± 12 K for the systemic component and Trot = 157 ± 19 K for the blueshifted component, and fractional abundance of NH3 relative to molecular hydrogen H2 are higher than those in other galaxies reported. The high temperature environment at the center may be mainly attributed to heating by the nuclear jets.

Dome Fuji on the Antarctic high plateau may be a good site for terahertz astronomy because of its high altitude of 3,810 m and low average temperature of −54°C. We have demonstrated that the opacity at 220 GHz from Dome Fuji in summer is very good and stable; τ = 0.045 ± 0.007. We have developed a transportable 30 cm telescope to map the Milky Way in the CO (J=4–3) and the [CI] (3P1–3P0) lines at Dome Fuji from 2014. It has a 9′ beam. Physical conditions such as density and temperature of molecular clouds could be derived from a direct comparison of CO (J=4–3) and [CI] (3P1–3P0) with CO (J=1–0) taken by the Columbia–CfA survey. We are also developing a 1.2 m sub-millimeter telescope. It will be equipped with a dual superconducting device (SIS) receiver for 500/800 GHz. The 1.2 m telescope produces a 2.2′ beam at 492 GHz and could map a molecular cloud entirely. It could also observe nearby galaxies in the CO (J=4–3), CO (J=7–6), [CI] (3P1–3P0), [CI] (3P2–3P1) and in continuum emission between 460–810 GHz.

An observational study is presented of the spectral evolution of gamma-ray burst (GRB) prompt emissions with the Suzaku Wide-band All-sky Monitor (WAM). We selected 6 bright GRBs exhibiting 7 well-separated fast-rise-exponential-decay (FRED) shaped light curves to investigate spectral changes by evaluating exponential decay time constants of the energy-resolved light curves. In addition, we carried out time-resolved spectroscopy of two of them which were located with accuracy sufficient to evaluate the time-resolved spectra with precise energy response matrices. The two imply different emission mechanisms; the one is well reproduced with a cooling blackbody radiation model with a power-law component, while the other prefers non-thermal emission model with a decaying turn over energy.

We performed mapping observations of the Fornax A west lobe with Suzaku in order to measure X-ray brightness distribution. Thanks to the low and stable background of Suzaku, we succeeded in detecting the faint diffuse X-ray emission from the west lobe. Performing careful corrections to the obtained images, we finally measured the X-ray brightness profile extending over the lobe. By comparing the X-ray and radio profiles, the magnetic field found to be fairly constant at ~1 μG over the lobe, while the electron energy distribution is suggested to concentrate on the lobe center.