Akihiro FURUZAWA, Koujun YAMASHITA, Yuzuru TAWARA Yasuo TANAKA and Takashi SONOBE (ISAS)

Abstract

We observed two distant clusters Cl0016+16 and A665 at redshift 0.545 and 0.18 2 by ASCA to determine the Hubble constant at high redshift using Sunyaev-Zel'dvich effect. ASCA observations with wide energy range and high efficiency provi de plasma temperature of each cluster precisely. Derived Hubble constant by usin g Cl0016+16 and A665 data are 41^{+15}_{-12} (Cl0016+16) and 47^{+17}_{-17} (A665) km/sec/Mpc. Spectral and image data from ASCA indicate the possibility th at the gas temperature decrease in the outer portion of clutser. From examining the uncertainty which include the influence of this temperature change, obtained value of the Hubble constant is probably not 100km/sec/Mpc, but nearly 50km/sec /Mpc.