That are thought to be the result of huge volumes of heated matter circling around and being consumed by a supermassive black hole
Space news (August 12, 2015) – Astrophysics; studying galaxies with extremely luminous centers looking for clues to high-speed, radio-signal-emitting jets extending thousands of light-years into space –
NASA space scientists working with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope think they have found a possible link between galaxy mergers and the presence of active galactic nuclei (AGN).
“The galaxies that host these relativistic jets give out large amounts of radiation at radio wavelengths,” explains Marco.“By using Hubble’s WFC3 camera we found that almost all of the galaxies with large amounts of radio emission, implying the presence of jets, were associated with mergers. However, it was not only the galaxies containing jets that showed evidence of mergers!”
Active galactic nuclei refer to the luminous center of a small percentage of galaxies viewed during the human journey to the beginning of space and time. Luminous centers space scientists often detect emitting two high-speed jets of plasma in opposite directions at right angles to the disk of matter surrounding the supermassive black hole believed to exist near the center of these galaxies. Powerful, radio-signal-emitting jets astrophysicists call relativistic jets they think could be powered by huge volumes of heated matter circling around and eventually being consumed by the supermassive black hole. Heated matter astrophysicists think could have been provided by the chaos of a recent merger with another galaxy.
How did they conduct the study?
NASA astrophysicists studied a large selection of galaxies with extremely luminous centers looking for signs of a recent merger with another galaxy. Data from several different additional studies was used to enhance the data set. Space scientists in this study looked at five different types of galaxies; two types with relativistic jets, two with luminous cores but no jets, and a set of regular inactive galaxies.
What did they find?
They found a large percentage of the galaxies viewed showed evidence of mergers with other galaxies, including all those with extremely luminous centers. They also found that a very small percentage of galaxies viewed formed AGNs with powerful radio emissions and even less relativistic jets extending thousands of light-years into space.
“We found that most merger events in themselves do not actually result in the creation of AGNs with powerful radio emission,” added co-author Roberto Gilli from Osservatorio Astronomico di Bologna, Italy. “About 40% of the other galaxies we looked at had also experienced a merger and yet had failed to produce the spectacular radio emissions and jets of their counterparts.”
Astrophysicists looking at the data provided through this survey of galaxies with AGNs believe it could be necessary for galaxies to merge to produce a host supermassive black hole with relativistic jets. They also think additional parameters need to exist for the merger to result in this spectacular and awe-inspiring sight. Possibly the result of two black holes of similar mass merging could power these high-speed jets viewed during the human journey to the beginning of space and time as excess energy is extracted from the black hole’s rotational energy is added to the mix.
“There are two ways in which mergers are likely to affect the central black hole. The first would be an increase in the amount of gas being driven towards the galaxy’s centre, adding mass to both the black hole and the disc of matter around it,” explains Colin Norman, co-author of the paper. “But this process should affect black holes in all merging galaxies, and yet not all merging galaxies with black holes end up with jets, so it is not enough to explain how these jets come about. The other possibility is that a merger between two massive galaxies causes two black holes of a similar mass to also merge. It could be that a particular breed of merger between two black holes produces a single spinning supermassive black hole, accounting for the production of jets.”
Astrophysicists and space scientists will now use both the Hubble Space Telescope and the Atacama Large Millimeter/Submillimeter Array (ALMA) to expand the search for additional galaxies with extremely luminous centers. This will enhance the survey and provide more data on additional parameters to help shed light on galaxies with AGNs. For now, we can only say it appears galaxies viewed exhibiting relativistic jets have merged with other galaxies.
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