In the X-ray light, a giant purple cloud can be seen in the centre of the Hercules A galaxy. The cloud is heated to millions of degrees by the energy generated by the infall of matter into the hungry black hole in the milky way. This supermassive black hole is 1,000 times as massive as the black hole at the center of the Milky way.
(NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA)
The largest black holes to grow faster than their galaxies, according to new research.
Two studies of separate groups of researchers found that the so-called supermassive black holes are bigger than the astronomers would have calculated from their environment alone. Supermassive black holes are massive gravity wells in the center of large galaxies.
No stress, but: The black holes are generally not growing, and they aren’t capable of eating their host galaxies for the dinner. [Science Fact or Fiction? The Plausibility of 10 Sci-Fi Concepts]
“The black hole is small in comparison with the whole galaxy, so we are very safe!” said Yang Guang, a graduate student at The Pennsylvania State University, who led one of the new studies.
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Yang’s research showed that the larger the galaxy, the faster the black hole grew in comparison with the birth rate of the galaxy’s stars. The other study found that the mass of the extreme black holes are about 10 times larger than one would expect if these central black holes grew at the same rate as the galaxies they inhabit.
Galaxies and their black holes
Astronomers are interested in the relationships between black holes and their galaxies, and for two reasons. First of all, if they can calculate the size of a on the basis of another, they can determine, say, the mass of a supermassive black hole, even if they are not directly able to measure. Secondly, there is an ongoing relationship between the two can help explain the laws that determine how galaxies are formed.
In the first study, published this month in the journal Monthly Notices of the Royal Astronomical Society and available on the preprint site ArXiv, Yang and his colleagues used data from more than 30,000 galaxies from the Great Observatories Origins Deep Survey (GOODS). The astronomical research combined observations from the Hubble Space Telescope, the Chandra X-ray Observatory and the Spitzer Space Telescope, and more than 500,000 galaxies from the Cosmic Evolution Survey (COSMOS), which makes use of both space – and ground-based telescopes to explore the universe. The galaxies are between 4.3 billion and 12.2 billion light-years from Earth.
The research team discovered that the larger the galaxy, the greater the ratio between the black hole growth and the growth of the star. A galaxy with 100 billion of the Earth the sun the worth of the star (a measurement known as solar-mass) has 10 times the ratio as a galaxy with 10 billion of the sun’s worth of stars. [The Strangest Black Holes in the Universe]
“Our paper suggests that large galaxies feed their black holes are more effective than small galaxies,” Yang told Live Science. “So, that large galaxies with a very large black holes. However, it is still an unsolved mystery, the black holes can affect galaxy formation in the back.”
Going to ultra
A second study, also available on ArXiv and will be published in April in the journal Monthly Notices of the Royal Astronomical Society, also found that the larger the galaxy, the stranger her relationship with a black hole.
That research, led by astrophysicist Mar Mezcua at the Institute of Space Sciences in Barcelona, Spain, focused on the 72 galaxies not more than about 3.5 billion light-years from Earth. The galaxies are all the “brightest cluster galaxies,” a term that refers to the largest and brightest galaxies in the nearby universe. With the help of X-ray and radio-wave data from the Chandra X-ray Observatory, the Australia Telescope Compact Array, the Karl G. Jansky Very Large Array and the Very Long Baseline Array, the researchers compared the masses of supermassive black holes to estimates made using traditional methods that assumed that black holes and their galaxies grow more or less at the same rate.
Instead of finding the two growing in lockstep, the research team discovered that the black holes in their study were 10 times greater than predicted by traditional means. In fact, many qualified and not only as supermassive black holes, which clock in at a few billion solar masses, but as ultramassive black holes, which can be up to 40 billion times the mass of the Earth and the sun.
Not know before that brightest cluster galaxies can host such massive black holes, the researchers reported. The black holes could have formed in two ways, they wrote. One possibility is that the black hole grew first and the galaxy grew. Another possibility is that these black holes are the descendants of “seed” black holes that arise when the galaxies were much younger and more productive in star formation. The bottom line is however, that black holes and their galaxies do not always grow as a matching set.
Editor’s note: This article was updated to correct a statement saying ultramassive black holes can be up to 40 “million” times the mass of the sun; they are up to 40 billion times the mass of our sun.
Original article on Live Science.