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 New material for splitting water
19.06.2018 | American Institute of Physics

nachricht Carbon nanotube optics provide optical-based quantum cryptography and quantum computing
19.06.2018 | DOE/Los Alamos 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: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Carbon nanotube optics provide optical-based quantum cryptography and quantum computing

19.06.2018 | Physics and Astronomy

How to track and trace a protein: Nanosensors monitor intracellular deliveries

19.06.2018 | Life Sciences

New material for splitting water

19.06.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>