Washington: A research team has discovered that the more massive black holes tend to be located in galactic environments with higher density, thus indicating that galaxies in a dense area often merge together, causing the growth of massive black holes.
Researchers at the National Astronomical Observatory of Japan ( NAOJ) investigated environment in which a galaxy with a massive black hole at its center exists.
The team collected the data on more than 10,000 AGN whose black hole mass had been already measured by spectroscopic observation with SDSS.
Next, data on galaxies surrounding active galaxies were gathered from galaxy catalogues of UKIDSS; the number of galaxies reached approximately 70 million. Using the virtual observatory, the team could automatically and efficiently extract only necessary galactic data from the large amount of data sets on those galaxies surrounding active galaxies. In addition, they developed new analysis method in order to obtain the density distribution of galaxies with a high degree of accuracy.
The results showed that the more massive black holes tend to be located in galactic environments with higher density. This connection between a massive black hole and the environment of its host galaxy is quite surprising since the radius of the overdense region of galaxies is 100 million times larger than the radius of a massive black hole.
The researchers also found that in regards to massive black holes with a solar mass of 100 million or less, there is no correlation between the black-hole mass and the galaxy distribution. This suggests that there is a possibility that the growth process may be different between black holes above or below 100 million solar masses.