Supermassive Black Holes the Source of Galactic Outbursts
Supermassive black holes are the source of many galactic outbursts in the Universe, according to new research that helped solve a longstanding mystery.
And no, I don't mean an outburst like some sort of celestial temper tantrum. Each year, various galaxies blast outward from their centers huge, wide-angled flows of material - pushing to their outer edges so much dust and gas that it could create more than a thousand stars the size of our Sun. Astronomers have long wondered what is the driving force behind these massive molecular outflows - that is, until now.
Researchers from the University of Maryland (UMD) have found the first observational evidence that a supermassive black hole at the center of a large galaxy can power these huge molecular outbursts. According to the new findings published in the journal Nature, these outflows remove massive quantities of star-making gas, which in turn influences the size, shape and overall fate of the host galaxy.
"The temptation is to ignore the supermassive black hole when studying galactic dynamics and evolution, but our study shows that you can't because it influences galaxies on the larger scale," co-author Marcio Meléndez said in a statement. (Scroll to read on...)
To reach their conclusion, the UMD team looked to the galaxy known as IRAS F11119+3257, which has an actively growing supermassive black hole deep inside its core. That is, unlike the large black hole at the center of our own Milky Way galaxy, this black hole is actively consuming large amounts of gas.
These types of black holes are called active galactic nuclei (AGN), and as they devour star-making material from their host galaxy's core, it creates friction that gives off electromagnetic radiation - such as X-rays and visible light. In addition, this intense radiation also generates powerful winds that force material away from the galactic center. This new study discovered that the AGN winds are so powerful that they can blast massive amounts of dust and gas to even the far outer edges of a galaxy.
Scientists had long theorized that the AGN winds and molecular outflows were connected, but this is the first time their suspicions have been directly confirmed. They used data collected in 2013 by Suzaku, an X-ray satellite operated by the Japan Aerospace Exploration Agency (JAXA) and NASA, as well as data from the European Space Agency's Herschel Space Observatory.
"This is the first galaxy in which we can see both the wind from the active galactic nucleus and the large-scale outflow of molecular gas at the same time," said lead author Francesco Tombesi.
Aside from supermassive black holes, star formation was also considered a possible source of these molecular outflows. However, this theory seems unlikely due to the brightness of IRAS F11119+3257's active nucleus - which is responsible for about 80 percent of the galaxy's overall radiation. This intense concentration of energy can't be explained be star formation alone, so researchers are confident that the AGN winds must be the primary driver.
It should be noted that the UMD team's findings are unique to the IRAS F11119+3257 galaxy, and thus far have not observed the same phenomenon in other galaxies - yet. They hope to study more candidate galaxies in the future using the satellite ASTRO-H, which JAXA and NASA will launch within the next year.
For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).