by Staff Writers
Tokyo, Japan (SPX) Oct 22, 2013

The difference of galactic density according to black-hole mass (the vertical axis shows the size of regions with enhanced galactic density: the bigger the size, the higher the density). The heavier black holes are located in galaxies with higher density for black holes with mass larger than ~10^8 solar mass. While the less massive black holes show no correlation between the mass of black holes and the density of galaxies.

A research team, led by reseacher at the National Astronomical Observatory of Japan (NAOJ), discovered that the more massive black holes tend to be located in galactic environments with higher density.

This finding indicates that galaxies in a dense area often merge together, causing the growth of massive black holes.

The research team investigated environment in which a galaxy with a massive black hole at its center exists.

The team’s research extended over data for approximately 70 million galaxies, with approximately 10,000 massive black holes researched.

This vast amount of data was collected through the Virtual Observatory; it connects a variety of astronomical databases around the world via the Internet, making it possible to comprehensively use the collected data.

The scientific paper on which this article is based appears in the Astrophysical Journal. (Komiya et al. “A Cross-correlation Analysis of Active Galactic Nuclei and Galaxies Using Virtual Observatory: Dependence on Virial Mass of Supermassive Black Hole”, published in the Astrophysical Journal, vol.775, article id.43)