Hajime Inoue

ASCA Observations of Luminous Infrared Galaxies: Evolution from Starburst to AGN?

We made a series of ASCA observations of Ultra Luminous Infrared Galaxies (ULIRGs), to reveal the origin of their luminosities and to test a proposed evolutionary scenario of ULIRGs. We discovered embedded AGN in some galaxies, but the relative contribution of AGN activity to the total luminosity varies significantly from galaxy to galaxy and has no correlation with the evolutionary sequence as mergers.

The ASCA Results of Gro J1744–28

We present the ASCA/GIS results of the transient source GRO J1744-28, the bursting X-ray pulsar, for the two times observations about one year apart. (the first and the second observations are on Feb. 27th 1996 and Mar. l6th 1997 respectively.) Since the discovery of GRO J1744-28 on Dec. 2 1995 with the BATSE observatory (Fishman et al. 1995; Kouveliotou et al.), thousands of Type II X-ray bursts, and sinusoidal pulsations have been observed in the X-ray band. No other source has ever been found to exhibit such unusual characteristics. Following each burst the flux decreases below, and recovers to the pre-burst persistent level (here after the dip) within a few seconds to a few minutes, depending on the total flux of the burst. We examined the spectrum of GRO J1744-28 during each persistent, dip, burst phases at the two observations. This is the first detail study of the spectra (l-10keV band) of GRO J1744-28.

The X-Ray Spectrum of Supernova SN1993J

SN1993J is very unique object which was discovered in the nearby Sb galaxy M81 (NGC 3031) on March 28[1]. The first detection of the radio emission was at 22.5 GHz by the VLA only 5 days after the optical outburst[2]. Subsequently X-ray emission was detected by ROSAT and ASCA at 6 days and 8 days after the explosion respectively. These emissions are expected when the SN shock front sweeps out the circumstellar matter (CSM). The early detection of radio and X-ray emission implies the existence of high-density CSM in the vicinity of the supernova(e.g. [3][4]).