Astronomers obtained the first resolved image of disturbed gaseous clouds in a galaxy 11 billion light-years away by using the Atacama Large Millimeter/submillimeter Array (ALMA). The team found that the disruption is caused by young powerful jets ejected from a supermassive black hole residing at the center of the host galaxy. This result will cast light on the mystery of the evolutionary process of galaxies in the early Universe.

It is commonly known that black holes exert strong gravitational attraction on surrounding matter. However, it is less well known that some black holes have fast-moving streams of ionized matter, called jets. In some nearby galaxies, evolved jets blow off galactic gaseous clouds, resulting in suppressed star formation. Therefore, to understand the evolution of galaxies, it is crucial to observe the interaction between black hole jets and gaseous clouds throughout cosmic history. However, it had been difficult to obtain clear evidence of such interaction, especially in the early Universe.

In order to obtain such clear evidence, the team used ALMA to observe an interesting object known as MG J0414+0534. A distinctive feature of MG J0414+0534 is that the paths of light traveling from it to Earth are significantly distorted by the gravity of another 'lensing' galaxy between MG J0414+0534 and us, causing significant magnification.

"This distortion works as a 'natural telescope' to enable a detailed view of distant objects," says Takeo Minezaki, an associate professor at the University of Tokyo.

Another feature is that MG J0414+0534 has a supermassive black hole with bipolar jets at the center of the host galaxy. The team was able to reconstruct the 'true' image of gaseous clouds as well as the jets in MG J0414+0534 by carefully accounting for the gravitational effects exerted by the intervening lensing galaxy.

"Combining this cosmic telescope and ALMA's high-resolution observations, we obtained exceptionally sharp vision, that is 9,000 times better than human eyesight," adds Kouichiro Nakanishi, a project associate professor at the National Astronomical Observatory of Japan/SOKENDAI. "With this extremely high resolution, we were able to obtain the distribution and motion of gaseous clouds around jets ejected from a supermassive black hole."

Thanks to such a superior resolution, the team found that gaseous clouds along the jets have violent motion with speeds as high as 600 km/s, showing clear evidence of impacted gas. Moreover, it turned out that the size of the impacted gaseous clouds and the jets are much smaller than the typical size of a galaxy at this age.

"We are perhaps witnessing the very early phase of jet evolution in the galaxy," says Satoki Matsushita, a research fellow at Academia Sinica Institute of Astronomy and Astrophysics. "It could be as early as several tens of thousands of years after the launch of the jets."

"MG J0414+0534 is an excellent example because of the youth of the jets," summarizes Kaiki Inoue, a professor at Kindai University, Japan, and the lead author of the research paper which appeared in the Astrophysical Journal Letters. "We found telltale evidence of significant interaction between jets and gaseous clouds even in the very early evolutionary phase of jets. I think that our discovery will pave the way for a better understanding of the evolutionary process of galaxies in the early Universe."
The earth, solar system, entire Milky Way and the few thousand galaxies closest to us move in a vast "bubble" that is 250 million light years in diameter, where the average density of matter is half as large as for the rest of the universe. This is the hypothesis put forward by a theoretical physicist from the University of Geneva (UNIGE) to solve a conundrum that has been splitting the scientific community for a decade: at what speed is the universe expanding? Until now, at least two independent calculation methods have arrived at two values that are different by about 10% with a deviation that is statistically irreconcilable. This new approach, which is set out in the journal Physics Letters B, erases this divergence without making use of any "new physics."

The universe has been expanding since the Big Bang occurred 13.8 billion years ago -- a proposition first made by the Belgian canon and physicist Georges Lemaître (1894-1966), and first demonstrated by Edwin Hubble (1889-1953). The American astronomer discovered in 1929 that every galaxy is pulling away from us, and that the most distant galaxies are moving the most quickly. This suggests that there was a time in the past when all the galaxies were located at the same spot, a time that can only correspond to the Big Bang. This research gave rise to the Hubble-Lemaître law, including the Hubble constant (H0), which denotes the universe's rate of expansion. The best H0 estimates currently lie around 70 (km/s)/Mpc (meaning that the universe is expanding 70 kilometres a second more quickly every 3.26 million light years). The problem is that there are two conflicting methods of calculation.

Sporadic supernovae

The first is based on the cosmic microwave background: this is the microwave radiation that comes at us from everywhere, emitted at the time the universe became cold enough for light finally to be able to circulate freely (about 370,000 years after the Big Bang). Using the precise data supplied by the Planck space mission, and given the fact that the universe is homogeneous and isotropic, a value of 67.4 is obtained for H0 using Einstein's theory of general relativity to run through the scenario. The second calculation method is based on the supernovae which appear sporadically in distant galaxies. These very bright events provide the observer with highly precise distances, an approach that has made it possible to determine a value for H0 of 74.

Lucas Lombriser, a professor in the Theoretical Physics Department in UNIGE's Faculty of Sciences, explains: "These two values carried on becoming more precise for many years while remaining different from each other. It didn't take much to spark a scientific controversy and even to arouse the exciting hope that we were perhaps dealing with a 'new physics'." To narrow the gap, professor Lombriser entertained the idea that the universe is not as homogeneous as claimed, a hypothesis that may seem obvious on relatively modest scales. There is no doubt that matter is distributed differently inside a galaxy than outside one. It is more difficult, however, to imagine fluctuations in the average density of matter calculated on volumes thousands of times larger than a galaxy.

The "Hubble Bubble"

"If we were in a kind of gigantic 'bubble', continues professor Lombriser, where the density of matter was significantly lower than the known density for the entire universe, it would have consequences on the distances of supernovae and, ultimately, on determining H0."

All that would be needed would be for this "Hubble bubble" to be large enough to include the galaxy that serves as a reference for measuring distances. By establishing a diameter of 250 million light years for this bubble, the physicist calculated that if the density of matter inside was 50% lower than for the rest of the universe, a new value would be obtained for the Hubble constant, which would then agree with the one obtained using the cosmic microwave background. "The probability that there is such a fluctuation on this scale is 1 in 20 to 1 in 5, says professor Lombriser, which means that it is not a theoretician's fantasy. There are a lot of regions like ours in the vast universe."
The earth, solar system, entire Milky Way and the few thousand galaxies closest to us move in a vast "bubble" that is 250 million light years in diameter, where the average density of matter is half as large as for the rest of the universe. This is the hypothesis put forward by a theoretical physicist from the University of Geneva (UNIGE) to solve a conundrum that has been splitting the scientific community for a decade: at what speed is the universe expanding? Until now, at least two independent calculation methods have arrived at two values that are different by about 10% with a deviation that is statistically irreconcilable. This new approach, which is set out in the journal Physics Letters B, erases this divergence without making use of any "new physics."

The universe has been expanding since the Big Bang occurred 13.8 billion years ago -- a proposition first made by the Belgian canon and physicist Georges Lemaître (1894-1966), and first demonstrated by Edwin Hubble (1889-1953). The American astronomer discovered in 1929 that every galaxy is pulling away from us, and that the most distant galaxies are moving the most quickly. This suggests that there was a time in the past when all the galaxies were located at the same spot, a time that can only correspond to the Big Bang. This research gave rise to the Hubble-Lemaître law, including the Hubble constant (H0), which denotes the universe's rate of expansion. The best H0 estimates currently lie around 70 (km/s)/Mpc (meaning that the universe is expanding 70 kilometres a second more quickly every 3.26 million light years). The problem is that there are two conflicting methods of calculation.

Sporadic supernovae

The first is based on the cosmic microwave background: this is the microwave radiation that comes at us from everywhere, emitted at the time the universe became cold enough for light finally to be able to circulate freely (about 370,000 years after the Big Bang). Using the precise data supplied by the Planck space mission, and given the fact that the universe is homogeneous and isotropic, a value of 67.4 is obtained for H0 using Einstein's theory of general relativity to run through the scenario. The second calculation method is based on the supernovae which appear sporadically in distant galaxies. These very bright events provide the observer with highly precise distances, an approach that has made it possible to determine a value for H0 of 74.

Lucas Lombriser, a professor in the Theoretical Physics Department in UNIGE's Faculty of Sciences, explains: "These two values carried on becoming more precise for many years while remaining different from each other. It didn't take much to spark a scientific controversy and even to arouse the exciting hope that we were perhaps dealing with a 'new physics'." To narrow the gap, professor Lombriser entertained the idea that the universe is not as homogeneous as claimed, a hypothesis that may seem obvious on relatively modest scales. There is no doubt that matter is distributed differently inside a galaxy than outside one. It is more difficult, however, to imagine fluctuations in the average density of matter calculated on volumes thousands of times larger than a galaxy.

The "Hubble Bubble"

"If we were in a kind of gigantic 'bubble', continues professor Lombriser, where the density of matter was significantly lower than the known density for the entire universe, it would have consequences on the distances of supernovae and, ultimately, on determining H0."

All that would be needed would be for this "Hubble bubble" to be large enough to include the galaxy that serves as a reference for measuring distances. By establishing a diameter of 250 million light years for this bubble, the physicist calculated that if the density of matter inside was 50% lower than for the rest of the universe, a new value would be obtained for the Hubble constant, which would then agree with the one obtained using the cosmic microwave background. "The probability that there is such a fluctuation on this scale is 1 in 20 to 1 in 5, says professor Lombriser, which means that it is not a theoretician's fantasy. There are a lot of regions like ours in the vast universe."