Nav: Home

New clues on dark matter from the darkest galaxies

December 18, 2019

They are called low-surface-brightness galaxies and it is thanks to them that important confirmations and new information have been obtained on one of the largest mysteries of the cosmos: dark matter. "We have found that disc galaxies can be represented by a universal relationship. In particular, in this study we analysed the so-called Low-Surface-Brightness (LSB) galaxies, a particular type of galaxy with a rotating disc called this way because they have a low-density brightness "says Chiara di Paolo, astrophysicist at SISSA and lead author of a study recently published in MNRAS together with Paolo Salucci (astrophysicist at SISSA) and Erkurt Adnan (Istanbul University).

The researchers analysed the speed at which the stars and gases that compose the galaxies subject matter of the study rotate, noting that the LSBs also have a very homogenous behaviour. This result consolidates several clues on the presence and behaviour of dark matter, opening up new scenarios on its interactions with bright matter.

Lights and shadows on matter

It is there but you cannot see it. Dark matter appears to account for approximately 90% of the mass of the Universe; it has effects that can be detected on the other objects present in the cosmos, and yet it cannot be observed directly because it does not emit light (at least for the way in which it has been searched for to date). One of the methods for studying it is that of rotation curves of the galaxies, systems that describe the trend of the speed of stars based on their distance from the centre of the galaxy. The variations observed are connected to the gravitational interactions due to the presence of stars and to the dark component of matter. Consequently, the rotation curves are a good way to have information on the dark matter based on its effects on what it is possible to observe. In particular, the analysis of the rotation curves can be conducted individually or on groups of galaxies that share similar characteristics according to the universal rotation curve (URC) method.

The novelty of the research lies in having applied the URC method for the first time, already used for other types of galaxies, to a large sample of low-surface-brightness galaxies, obtaining similar results. "We have compared rotation curves of various LSB galaxies finding that there is no discontinuity but gradual and ordered variations starting from the small to the large. Something similar was also observed for spiral galaxies," explains Salucci, the other author of the study: "This method was applied for the first time in 1996, and to date it has shown that all disc, spiral, dwarf and now also the LSB galaxies can be represented by a universal relationship. This means that we are able to express an ordered trend through a formula which, keeping account of very few parameters, describes how dark matter and luminous matter are distributed".

New possible scenarios

As it often happens in scientific research, the study has revealed further surprising and unexpected results. "We have discovered relationships of scale between the properties of the stellar disc and those of the dark matter halo, for example a relationship between the dimensions of the stellar discs and the dimensions of the internal region with a constant density of the dark matter halo" explains Chiara Di Paolo. "Furthermore, by comparing the relationships found in the LSB with those obtained in different types of galaxies, we have found that they are all almost coincidental. And it has been a great surprise to verify that galaxies with a very different morphology and history show the same relationships between the properties of dark matter and those of luminous matter". This result, together with some specific features of LSB galaxies, opens up a new series of scenarios including that of the existence of another type of direct interaction, in addition to the gravitational one, between the two types of matter that form galaxies. A fascinating idea to be verified by new observations.
-end-


Scuola Internazionale Superiore di Studi Avanzati

Related Dark Matter Articles:

Looking for dark matter
Dark matter is thought to exist as 'clumps' of tiny particles that pass through the earth, temporarily perturbing some fundamental constants.
New technique looks for dark matter traces in dark places
A new study by scientists at Lawrence Berkeley National Laboratory, UC Berkeley, and the University of Michigan -- published today in the journal Science - concludes that a possible dark matter-related explanation for a mysterious light signature in space is largely ruled out.
Researchers look for dark matter close to home
Eighty-five percent of the universe is composed of dark matter, but we don't know what, exactly, it is.
Galaxy formation simulated without dark matter
For the first time, researchers from the universities of Bonn and Strasbourg have simulated the formation of galaxies in a universe without dark matter.
Taking the temperature of dark matter
Warm, cold, just right? Physicists at UC Davis are using gravitational lensing to take the temperature of dark matter, the mysterious substance that makes up about a quarter of our universe.
New clues on dark matter from the darkest galaxies
Low-surface-brightness (LSB) galaxies offered important confirmations and new information on one of the largest mysteries of the cosmos: dark matter.
A new approach to the hunt for dark matter
A study that takes a novel approach to the search for dark matter has been performed by the BASE Collaboration at CERN working together with a team at the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU).
Could the mysteries of antimatter and dark matter be linked?
RIKEN researchers and collaborators have performed the first laboratory experiments to determine whether a slightly different way in which matter and antimatter interact with dark matter might be a key to solving both mysteries.
Placing another piece in the dark matter puzzle
A team led by Prof Dmitry Budker has continued their search for dark matter within the framework of the 'Cosmic Axion Spin Precession Experiment' (or 'CASPEr' for short).
Physicists have found a way to 'hear' dark matter
Physicists at Stockholm University and the Max Planck Institute for Physics have turned to plasmas in a proposal that could revolutionise the search for the elusive dark matter.
More Dark Matter News and Dark Matter Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.