October 17, 2013
Virtual Observatory Study Explains How Black Holes Get So Massive
Lee Rannals for redOrbit.com - Your Universe Online
Astronomers using a "Virtual Observatory" set out to study "fat" black holes that grow up to more than one million solar masses.
Some massive black holes are observed as active galactic nuclei (AGN), which attract surrounding gas and release huge amounts of energy. The team collected the data on more than 10,000 AGN whose black hole mass had already been measured by spectroscopic observation.
Scientists have wondered exactly how a massive black hole gets fat, with one leading theory saying mutual interaction between galaxies could be to blame. For this theory to be correct, there must be a relationship between properties of a supermassive black hole and the environment of its host galaxy.
The Virtual Observatory is a system to make integrated use of various astronomical databases from around the globe. The team used the system to automatically and efficiently extract only necessary galactic data from the large amount of data sets on 70 million galaxies. They also developed a new analysis method to help obtain the density distribution of galaxies with a high degree of accuracy.
Researchers found that more massive black holes tend to be located in galactic environments with higher densities. The scientists said this connection between a fat black hole and the environment of its host galaxy was surprising because the radius of the over dense region of galaxies is 100 million times larger than the radius of a massive black hole.
The team also found black holes with a solar mass of 100 million or less have no correlation between black hole mass and galaxy distribution. This suggests there is a possibility that the growth process could be different between the largest of the black holes, and the lesser yet still massive black holes.
"Through this research, we have rediscovered the real potential of the virtual observatory, which can process such a huge amount of data in a very short time," Yutaka Komiya of the National Astronomical Observatory of Japan (NAOJ) and lead researcher of the study published in The Astrophysical Journal said in a statement.
The research method used in the study could be applied to study larger amounts of observation data, such as that captured by the new wide-field cameras of the Subaru Telescope.
Yuji Shirasaki, one of the research team members, said the study still left some unanswered questions.
"A large part of the total picture, such as the formation mechanism of relatively small massive black holes, still remains unknown; one of the reasons is the lack of observation. There are a lot of things to explore, including the mystery of how massive black holes are born," Shirasaki said in a statement.