SUMMARY OF PROPOSAL 81601

MS. AYA KUBOTA
AYA@AMALTHEA.PHYS.S.U-TOKYO.AC.JP

UNIVERSITY OF TOKYO
HONGO 7-3-1
BUNKYO-KU
TOKYO JAPAN 113-0033
Tel: 03-5841-4202 Fax: 03-5841-4158
Medium: CD ROM
Subject: NORMAL GALAXIES

Ultra-luminous X-ray source in M33


ABSTRACT

Some luminous point-like X-ray sources (ULXs) seen in nearby spiral galaxies are promising blackhole binaries. In recent ASCA observation (AO8), from two ULXs in IC 342, we have detected remarkable transitions between two characteristic spectral states, which provides a strong evidence for the blackhole nature of these ULXs. Furthermore, this indicates the possibility that we can extend our study of blackhole binaries to extra-Galactic sources. One of the nearest spiral galaxies, M33, was observed with ASCA in PV phase, and ten point-like sources were detected. Among them, X-8 is known as the nearest ULX with X-ray luminosity of 1E39 erg/s, and three bright sources of >1E38 erg/s can be blackhole binaries considering their hardness ratio. Together with its size and distance, M33 is the best target to examine the ULXs nature and extra-Galactic blackhole binaries. We therefore propose additional multiple (2 times) observations of M33. By these observations together with the PV phase observation, we can discuss the spectral transition and variation of disk parameters, and we can identify other sources with detailed spectral study.

CO-INVESTIGATORS
CO-I NAME INSTITUTE COUNTRY
KAZUO MAKISHIMAUNIV OF TOKYOJAPAN
NAOKO IYOMOTOUNIV OF TOKYOJAPAN
TSUNEFUMI MIZUNOUNIV OF TOKYOJAPAN
YASUSHI FUKAZAWAUNIV OF TOKYOJAPAN
YUKIKATSU TERADAUNIV OF TOKYOJAPAN
KAZUHISA MITSUDAISASJAPAN
YOSHITAKA SAITOISASJAPAN
TATEHIRO MIHARARIKENJAPAN

TARGETS

TARGET NAMEPRIRADECTIMETCOFFGISSIS CNTOBS
1)M33
A
23.4621 30.6600
100 ks
N
N
P
0.40000
2