Johns Hopkins University •

Massive Black Holes Can Block Star Formation, Study Revealed!

October 23, 2014 By Rebecca McGhee Leave a Comment

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.

Leaky Galaxy May Fling Some Light On The Universe Evolution

October 11, 2014 By Jason Leathers 3 Comments

About 400 million years ago, the universe was very dark until the first star producing galaxies started to make ultraviolet light, which ultimately lighted up the cosmos.

Recently, NASA-funded research team with grant number 12886 at the Johns Hopkins University discovered a compact galaxy named as J0921+4509. The researchers believed that it possesses similar characteristics needed to lighten up the early universe. It is actually emitting photons with an energy that ionize hydrogen atoms. This galaxy also enables over 20% of its ultraviolet radiation to leak through the dust clouds causing it to emit strong levels of ultraviolet light and providing hints to astronomers on how the earliest galaxies of the universe may have likely behaved.

J0921+4509 is located 2.9 million years away from the Milky Way galaxy. It generates stars in a compact region similar to the rate of budding galaxies of earliest times. Moreover, the galaxy whips around 50 stars having the same mass as the sun every year that is 33 times more than the number of stars that the Milky Way produces for the same period.

Brian Siana, an astronomer from the University of California, Riverside stated that, “That’s quite high. This is roughly the fraction that we think all galaxies in the early universe had to have in order to ionize the hydrogen in the intergalactic medium.”

Thousands of years after the Big Bang, the cosmic scattered protons and electrons started to cool and developed the first atom of hydrogen. The fact ultimately resulted in the creation of hydrogen walls along with the clouds of cosmic dust, which has the ability to absorb ultraviolet radiation. This averted light from fleeing and blotched the dark ages of the universe.

With the passage of time, these radiations become too strong that it re-ionized the hydrogen. It actually happens when the photons gather enough energy in order to break up the electrons from the hydrogen atoms, which resulted in lighting up the previously dark universe. The astronomers think that, the radiation that broke electrons come from stellar births, but they are not sure about that.

Sanchayeeta Borthakur, an astronomer from the Johns Hopkins University stated that, “The galaxies contains star forming regions that are wrapped with cold gases so the radiation won’t come out. If we want to know that how the radiation gets out of the galaxy, we need to learn the mechanisms that ionized the universe.” He further stated that, it seems that the newly discovered galaxy might provide some hints concerning how the early universe lighted up.

Moreover, the researchers have been in a long quest of finding a ‘holey’ galaxy to examine how star-produced radiation plays a role in ionization process. For this purpose, the researchers placed the particular galaxy with the help of radiation leak measurement method and Cosmic Origin Spectrograph aboard the Hubble Space Telescope. As per the statement of researcher’s team “a combination of unusually strong winds, intense radiation and a massive, highly star-forming galaxy” for the validity of the indicator.

Borthakur stated that, “The confirmation of the indicator is key and now people can use this indicator to study distant galaxies at longer wavelengths.”

The study is published in the journal ‘Science’.

ICE Continents: Facts that Jupiter’s Moon Europa Resembles Earth

September 10, 2014 By Jason Leathers Leave a Comment

According to the scientists thought, the tectonics might be essentially responsible for the surface features on Jupiter’s icy moon Europa. At present, they also have a crucial evidence for this thought as well.

The scientists stated that there are segments of the ice crust of the Jupiter’s moon Europa which are usually pulled and pushed by some of the basic forces which are responsible for re-arranging the Earth Continents. According to the Astrobiologists, in the stalk for the habitats, vigorous tectonics seems to be a good sign.

The scientists working with the Galileo orbiter projected the notion that bold lines, fine ridges, and other features on Europa’s surface represented a frosty form of tectonics while it rayed back the first close images of the moon early in its 1995 to 2003 work.

Simon Kattenhorn, a senior structural geologist at the Conoco Phillips Company in Houston stated that “On Europa, they did see features that were very evocative of plates that looked like they had displaced.”

Currently, the world is in need of a stronger footing rather than “looks like,” statement. For this reason Dr. Katternorn and Louise Prockter of the Johns Hopkins University’s Applied Physics Laboratory in College Park, Md., embark a new analysis in this week’s issue of the journal Nature Geo-Science.

According to the previous researches conducted by Dr. Prockter and Dr. Katterhorn discloses a very convincing argument. He said ‘Europa had the equivalent of Earth’s mid-ocean ridges, along which magma wells up to form new crust. On Europa, ice or slush would be welling up through the cracks.

Way back in 2004, Katterhorn and mates published a paper on one more Earth-like tectonic process on Europa: strike-slip faults. However, they actually missed some crucial piece: facts and proof for subduction – a way to get rid of the old crust to make way for the new. This is the evidence Katterhorn and Prockter present in Nature Geo-Science.

With the help of the high-resolution images from Galileo of a 52,000 square-mile patch of Europa’s surface, the duo worked toward the back from existing plate positions in order to renovate the region’s pattern/design as it would have appeared a few million years ago. In fact, they used the similar strategy that the geophysicists have used to reconstruct the shapes and locations of Earth’s crustal plates as they would have appeared hundreds of millions of years ago.

However, it has been observed that the process of subduction removes material from the surface with the passage of time, such nostalgic renovations put down blank spaces where the former crust would have been, like a jigsaw puzzle a few pieces introverted of whole. In no doubt, there were two researchers that found a 7,700-square-mile lump of lost scab about 62 miles wide at its widest end. Its primary border coordinated with two features that the team recognized from the images as two closely spaced subduction systems.

Besides, edges, faults, and other linear features come to an unexpected end and where one ice plate begins to dive under another along a projected subduction system. The team of researchers had also recognized what look needs to be put down of so-called cryolava, sludge exploded tenderly over the facade from vents. These were set along one of the subduction areas, much reminiscent of the volcanoes that dot the borders of the Pacific Ocean’s “ring of fire.

Altogether, these two researchers recognized eight lines of proof for subduction on Europa, a process they afterwards renamed as subsumption. While the vanishing ice may depart from the surface as it is being subsumed by the stove ice below.

Still before the new study, the belief of tectonics on Europa was possibly the last elucidation ranking for the features on moon’s surface. The Europa’s current surface is ranging from 40 million to 90 million years old and is one of the youngest surfaces in the solar system; the researchers’ says.

Perhaps, still there are some questions that need to be answered. Usually, scientists claims that the crust was adjusting to the fresh material being added, slimming down nearby or a crumpling of the crust into mountains, for example. But they didn’t see any such thing actually happening.

For this reason, the researchers had come up with several potential explanations to resolve this discrepancy. Such as, the surface might be folding over long distances which make the folding hard to mark, or the outer shell may possible be getting thicker with time. However none of these explanations can reasonably report for the comparatively fast, extensive repaving of the surface.

In fact, the actual process of subsumption on Europa is not yet clear.

Certainly, the process of subduction happens when denser ocean surface grinds beneath more floating continental crust. It is then melted and returned to the surface at scattering edges. But there is still a confusion that if each plate of ice involved in the proposed subsumption activity on Europa has such a density difference. It is hence unclear how subduction can actually occur on Europa.

Categories