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A recent study revealed that the massive black holes emitting radio-frequency-particles at near-light speed can block the formation of new stars in mature galaxies.

The study revealed that the jets of ‘radio-frequency-feedback’ flowing from mature galaxies’ central black hole eventually thwart hot free gas from cooling and collapsing into baby stars.

Tobias Marriage, assistant professor of physics and astronomy at Johns Hopkins and co-lead author of the study stated that, “As you look back into the past history of the universe, you see these galaxies forming stars. At some point, they stop forming stars and the question is: Why? Basically, these active black holes give a reason for why stars stop forming in the universe.”

The study has been published in the Monthly Notices of the Royal Astronomical Society journal.

A well-known research technique is being used by the scientists in order to make these discoveries possible. Sunyaev–Zel’dovich effect signature found by Johns Hopkins postdoctoral fellow Megan Gralla, which is typically used to study large galaxy clusters and can also be used for learning a great deal about smaller star formations. Sunyaev–Zel’dovich effect happens when high-energy electrons in hot gas interact with faint light in the cosmic microwave background, light left over from the earliest times when the universe was a thousand times hotter and a billion times denser than today.

Gralla said, “Sunyaev–Zel’dovich effect is typically used to study clusters of hundreds of galaxies, though the galaxies we are looking for are much smaller and have just a companion or two. Actually, we are asking a different question than what has been formerly asked. We are using a technique that’s been around for some time and that researchers have been very successful with, and we’re using it to answer a totally different question in a totally different subfield of astronomy.”

Eiichiro Komatsu, director of the Max Planck Institute for Astrophysics in Germany and an expert in the field who was not involved in the research stated that, “I was shocked when I saw this research, because I have never assumed that detecting the SZ effect from active galactic nuclei was possible. I was actually wrong. It makes those of us who work on the SZ effect from galaxy clusters feel old; research on the SZ effect has entered a new era.”

When we look into the space, the hot gas haggard into a galaxy can cool and condense to make stars. Some gas also flows into the black hole of the galaxy that grows collectively with the stellar population. The cycles repeat at regular intervals, more hot gas is pulled into the galaxy that cool and condense, more stars begin to shine and the central black hole gets bigger.

Marriage, Gralla, along with their fellow colleagues found that the elliptical galaxies with radio-frequency feedback—relativistic radio-frequency-emitting particles shelling from the massive central black holes at their center at close to the speed of light—all contain hot gas and a scarcity of baby stars. This seems to be a strong evidence for their hypothesis that this radio-frequency feedback is the “off switch” for star formation in mature galaxies.

Marriage further stated that, “It’s not yet clear why black holes in mature elliptical galaxies begin to emit radio-frequency feedback. The exact mechanism behind this is not fully understood and there are still debates.”

Furthermore, this study poses new challenges to the theory of galaxy formation, as there were hardly any data which told us how much hot gas there is around galaxies,” Komatsu said.

Marriage and Gralla were joined as co-lead authors by Devin Crichton, a Johns Hopkins graduate student in physics and astronomy, and Wenli Mo, a physics and astronomy undergraduate student who earned her degree in May 2011. She is now studying at the University of Florida on a National Science Foundation Graduate Fellowship.

The team of researchers used data from the Atacama Cosmology Telescope, a 6-meter telescope in northern Chile; the National Radio Astronomy Observatory’s Very Large Array in New Mexico and its Green Bank Telescope in West Virginia; the Parkes Observatory in Australia; and the European Space Agency’s Herschel Space Observatory.

The DNA of a 45000 year old bone of a Siberian man has been recently examined by the researchers to find out when human and Neanderthals first interbred. On record, this is an oldest genome sequence of Homo sapiens exposing a mysterious population that may once have spanned northern Asia. The study is published in the Nature journal.

The oldest human genome also revealed that the closest extinct relatives of the modern humans were the Neanderthals who lived in Europe and Asia and vanished around 40,000 years ago. The Neanderthals interbred with ancestors of modern humans when modern humans began spreading out of Africa and today 1.5 to 2.1 percent of the DNA of anyone living outside Africa is Neanderthal in origin, study reveals.

“It remains vague when interbreeding between Neanderthals and modern humans happened. But it probably ranged between 37000 to 86000 years ago,” researchers stated.

The researchers examined the bone (human left femur), discovered by Nikolai Peristov, an artist and mammoth ivory collector on the left bank of the river Irtysh near the settlement of Ust’-Ishim in western Siberia in 2008. The age of the man’s bone to be is about 45,000 years old, researchers stated.

Janet Kelso, co-author of the study and a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, told Live Science, “This is the earliest directly dated modern human outside of Africa and the Middle East, and the oldest modern human [genome] to have been sequenced.”

Formerly, the researchers had proposed modern humans firstly populated Asia by traveling towards southern, coastal route that gave rise to the present-day people of Oceania, while a later, more northern migration, gave rise to mainland Asians. Kelson stated, “the researchers’ evidence for the modern human presence in Siberia 45,000 years ago specifies that the early modern humans were not just migrated to Eurasia through a southern route as previously suggested.”

The researchers further examined the carbon and nitrogen isotopes present in the man’s bone proposes that he ate C3 plants, which rule cooler, wetter, cloudier regions such as garlic, eggplants, pears, beans and wheat as well as animals that also dined on C3 plants. Though, the study analysis reveals that he might have eaten aquatic foods like fresh water fish.

The DNA analysis of mans’s bone revealed that the he was closely related to present-day Asians and to early Europeans. “From this we conclude that the population to which the Ust’-Ishim individual belonged diverged from the ancestors of present-day Europeans and Asians before, or at around the same time as, these groups diverged from one another,” Kelso said.

The researchers believed that 45,000 years old man carried a similar level of Neanderthal ancestry as present-day Eurasians and the Neanderthal genes moved into the ancestors of this man 7,000 to 13,000 years before he lived.

The results of the study propose that modern humans and Neanderthals interbred around 50,000 to 60,000 years ago, “which is close to the time of the major expansion of modern humans out of Africa and the Middle East,” Kelso added.

Massive Black Holes Can Block Star Formation, Study Revealed!

Scientists Sequenced A 45000-Year-Old Man’s Genome

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