Spectral and timing studies of a sample of hyperluminous X-ray sources

Hyperluminous X-ray sources (HLXs) with X-ray luminosities above 1e42 erg/s are very likely the long-sought intermediate-mass black holes (IMBHs) of 1e2- 1e5 solar masses, as demonstrated by the recent intensive studies of HLX-1 (Farrell et al. 2009), the only HLX known so far. To better study the HLX/IMBH populations, we have searched for new HLXs across the whole sky with the ROSAT All Sky Survey (RASS), yielding a sample of 10 new HLXs. Here we request 150 ks to observe five HLXs with XMM/EPIC to determine the fine spectral features and associated accretion states, and to study the correlated spectral and timing properties in hope to estimate the black hole masses.