|Budget Amount *help
¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1998 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
If MACHOs are primordial black holes of mass -0.5M<@D2(]SY.sun.[)@>D2 (BHMACHO), it is extremely difficult, if not impossible, to identify BHMACHOs by their accretion-driven emission. However using gravitational wave detectors, BHMACHOs maybe identified. There may exist -5 x 10<@D18@>D1 BHMACHO binaries in the halo up to -50kpc whose coalescing time due to the emission of gravitational waves is comparable to the age of the universe. This means that the event rate will be 5 x 10<@D1-2@>D1 events/yr/galaxy and several events/yr within 15 Mpc are expected. The gravitational waves from such coalescing BHMACHO binaries, if they exist, can be detected by LIGO, VIRGO, TAMA and GEO within next 5 years. (]SY.encircledC.[) 1998 Elsevier Science B.V.All rights reserved.
If MACHOs are black holes of mass -0.5 M_<<of sun>>, they must have been formed in the early universe when the temperature was -1 GeV.We estimate that in this case in our Galaxy's halo out to -50 kpc there exist -5 x l0^8 black hole binaries the coalescence times of which are comparable to the age of the universe, so that the coalescence rate will be 5 x 10^<-2> events yr^<-1> per galaxy. This suggests that we can expect a few events per year within 15 Mpc. The gravitational waves from such coalescing black hole MACHOs can be detected by the first generation of interferometers in the LIGO/VIRGO/TAMA/GEO network. Therefore, the existence of black hole MACHOs can be tested within the next 5 yr by gravitational waves.
Subject headings : black hole physics - dark matter - gravitation - gravitational lensing - Galaxy : halo