Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Spinning rugby balls: The rotation of the most massive galaxies

23.05.2018

By targeting the most massive galaxies in our universe, astronomers have studied how their stars move. The results are surprising: while half of them spin around their short axis as expected, the other half turn around their long axis. Such kinematics are most likely the result of a special type of galaxy merger, involving already massive, similar-mass galaxies. This would imply that the growth of the most massive and the largest galaxies is governed by these rare events.

Surveying the extremes of the galaxy population


Mean stellar velocities: blue parts move towards, red away from us. The rotation around the long axes (r.) applies only to a small fraction of galaxies. This increases as galaxies become more massive.

MUSE/D. Krajnovic

Measuring the way stars move within galaxies is a very powerful way of learning about the internal structure of galaxies, especially properties such as their three-dimensional shape and, ultimately, what their gravitational potential is like.

To study the largest and most massive galaxies, a science team led by Davor Krajnovic from the Leibniz Institute for Astrophysics Potsdam (AIP) selected a sample of some of the brightest galaxies up to a distance of 800 million light years.

These live in large ensembles of galaxies, within some of the most densely populated regions of our Universe, such as the Shapley Supercluster. They are also very bright and rare.

The most massive galaxies are about one hundred times more massive than our own galaxy the Milky Way, which itself already has a stellar mass of 60 billion suns. They also have almost no gas, most of their stars are very old (at least 10 billion years) and do not form stars anymore.

Unfortunately, these galaxies are too far from us to be resolved into individual stars and their motions. One can only look at the average motions of stars within certain regions.

“This is what integral-field spectrographs are good at”, explains Davor Krajnovic. „We observed these galaxies with MUSE, the wonderful integral-field spectrograph on the ESO's Very Large Telescope on Cerro Paranal in Chile. Massive galaxies can have all sorts of kinematics, some spin like frisbees, but most have no specific sense of rotation. We observed the most massive galaxies and found them to be different from other galaxies.”

From discs to rugby balls

The majority of intermediate-mass galaxies shows very regular stellar motions, as one would expect from discs like our Milky Way. In such galaxies, the sense of rotation is well defined around the short axis of the object; the angular momentum is aligned with the minor axis of an oblate spheroid.

“We knew that about only 15% of the intermediate mass galaxies have irregular kinematics or even don’t show much rotation at all”, says Krajnovic. “For such galaxies, the sense of rotation is often not aligned with any of the symmetry axes of the galaxy, and these galaxies are of nearly spherical shape, or are elongated resembling rugby balls. Some of them have an interesting alignment and rotate around the long axis of the galaxy. Only a few cases of these were known.”

In this new study published in the Monthly Notices of the Royal Astronomical Society, the authors showed that these galactic “spinning rugby balls” are much more common than thought previously if one looks at the extremely massive galaxies, the high-mass end of the galaxy population.

The result is interesting as it points to a very specific formation scenario for these galactic giants. Numerical simulations indicate that rotation along the long axis is indicative for a merger of two massive galaxies with similar size (and mass) when they are on special trajectories: sort of a head-on collision in space.

Such galaxy collisions are violent events that completely reshape the internal structures of the progenitor galaxies. The remnant galaxies resemble spinning rugby balls. Stellar orbits also become much more complex, resulting in kinematics where the simple ordered motion is substituted with complex streaming around any of the three axes of a spheroid. The most massive galaxies are the end points of galaxy formation, and deservedly turn out to be the most complex stellar systems. This study helps us unveil the mystery of how the most massive galactic systems in the Universe come into existence.

Scientific contact at AIP
Dr. Davor Krajnović, 0331-7499 237, dkrajnovic@aip.de

Media contact
Franziska Gräfe, 0331-7499 803, presse@aip.de

Weitere Informationen:

https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/sty1031/4985842
https://arxiv.org/abs/1802.02591

Dr. Janine Fohlmeister | idw - Informationsdienst Wissenschaft
Further information:
http://www.aip.de

Further reports about: AIP Astrophysik Galaxies Milky Way Very Large Telescope massive galaxies

More articles from Physics and Astronomy:

nachricht ASU astrophysicist helps discover that ultrahot planets have starlike atmospheres
13.08.2018 | Arizona State University

nachricht UT-ORNL team makes first particle accelerator beam measurement in six dimensions
13.08.2018 | DOE/Oak Ridge National Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

Im Focus: A molecular switch may serve as new target point for cancer and diabetes therapies

If certain signaling cascades are misregulated, diseases like cancer, obesity and diabetes may occur. A mechanism recently discovered by scientists at the Leibniz- Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin and at the University of Geneva has a crucial influence on such signaling cascades and may be an important key for the future development of therapies against these diseases. The results of the study have just been published in the prestigious scientific journal 'Molecular Cell'.

Cell growth and cell differentiation as well as the release and efficacy of hormones such as insulin depend on the presence of lipids. Lipids are small...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Can radar replace stethoscopes?

14.08.2018 | Medical Engineering

The end-Cretaceous extinction unleashed modern shark diversity

14.08.2018 | Life Sciences

Light-controlled molecules: Scientists develop new recycling strategy

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>