That grisly fate is unlikely, a new study now suggests.
While astronomers know that such collisions have probably occurred in the past, the new computer simulations show that instead of destroying a galaxy, these collisions “puff up” a galactic disk, particularly around the edges, and produce structures called stellar rings.
The finding solves two mysteries: the likely fate of the Milky Way at the hands of its satellite galaxies -- the most massive of which are the Large and Small Magellanic Clouds -- and the origin of its puffy edges, which astronomers have seen elsewhere in the universe and dubbed “flares.”
The mysterious dark matter that makes up most of the universe plays a role, the study found.
Astronomers believe that all galaxies are embedded within massive and extended halos of dark matter, and that most large galaxies lie at the intersections of filaments of dark matter, which form a kind of gigantic web in our universe. Smaller satellite galaxies flow along strands of the web, and get pulled into orbit around large galaxies such as our Milky Way.Ohio State University astronomer Stelios Kazantzidis and his colleagues performed detailed computer simulations of galaxy formation to determine what would happen if a satellite galaxy -- such as the Large Magellanic Cloud and its associated dark matter -- collided with a spiral galaxy such as our own.
The results may ease the mind of anyone who feared that our galactic neighbors and their associated dark matter would eventually destroy our galactic disk -- albeit billions of years from now.
Kazantzidis couldn’t offer a 100-percent guarantee, however.
“We can’t know for sure what’s going to happen to the Milky Way, but we can say that our findings apply to a broad class of galaxies similar to our own,” Kazantzidis said. “Our simulations showed that the satellite galaxy impacts don't destroy spiral galaxies -- they actually drive their evolution, by producing this flared shape and creating stellar rings -- spectacular rings of stars that we’ve seen in many spiral galaxies in the universe.”
He and his colleagues didn’t set out solely to determine the fate of our galaxy. In two papers that have appeared in the Astrophysical Journal, they report that their simulations offer a new way to test -- and validate -- the current cosmological model of the universe.
According to the model, the universe has contained a certain amount of normal matter and a much larger amount of dark matter, starting with the Big Bang. The exact nature of dark matter is unknown, and scientists are hunting for clues by studying the interplay between dark matter and normal matter.
This is the first time that collisions between spiral galaxies and satellites have been simulated at this level of detail, Kazantzidis said, and the study revealed that galaxies’ flared edges and stellar rings are visible signs of these interactions.
Our galaxy measures 100,000 light-years across (one light year equals six trillion miles). Yet we are surrounded by a cloud or “halo” of dark matter that’s 10 times bigger -- 1 million light-years across, he explained.
While astronomers envision the dark matter halo as partly diffuse, it contains dense regions that orbit our galaxy in association with satellite galaxies, such as the Magellanic Clouds.
“We know from cosmological simulations of galaxy formation that these smaller galaxies probably interact with galactic disks very frequently throughout cosmic history. Since we live in a disk galaxy, it is an important question whether these interactions could destroy the disk,” Kazantzidis said. “We saw that galaxies are not destroyed, but the encounters leave behind a wealth of signatures that are consistent with the current cosmological model, and consistent with our observations of galaxies in the universe.”
One signature is the flaring of the galaxy’s edges, just as the edges of the Milky Way and of other external galaxies are flared.
We consider this flaring to be one of the most important observable consequences of interactions between in-falling satellite galaxies and the galactic disk.”
In both articles, the researchers considered the impacts of many different smaller galaxies onto a larger, primary disk galaxy. They calculated the likely number of satellites and the orbital paths of those satellites, and then simulated what would happen during collision, including when the dark matter interacted gravitationally with the disk of the spiral galaxy.
None of the disk galaxies were torn apart; to the contrary, the primary galaxies gradually disintegrated the in-falling satellites, whose material ultimately became part of the larger galaxy.
The satellites passed through the galactic disk over and over, and on each pass, they would lose some of their mass, a process that would eventually destroy them completely.
Though the primary galaxy survived, it did form flared edges which closely resembled our galaxy’s flared appearance today.
“Every spiral galaxy has a complex formation and evolutionary history,” Kazantzidis said. “We would hope to understand exactly how the Milky Way formed and how it will evolve. We may never succeed in knowing its exact history, but we can try to learn as much as we can about it, and other galaxies like it.”
His coauthors included James Bullock from the University of California at Irvine, Andrew Zentner from the University of Pittsburgh, Andrey Kravtsov from the University of Chicago, Leonidas Moustakas from NASA’s Jet Propulsion Laboratory (JPL) , and Victor Debattista from the University of Central Lancashire in the UK.
Kazantzidis’ research was funded by the Center for Cosmology and Astro-Particle Physics at Ohio State. Other funding came from the National Science Foundation, NASA, the University of Pittsburgh, and the University of Chicago. The numerical simulations were performed on the zBox supercomputer at the University of Zurich and on the Cosmos cluster at JPL.Contact: Stelios Kazantzidis, (614) 247-1501; firstname.lastname@example.org
Stelios Kazantzidis | EurekAlert!
New Method of Characterizing Graphene
30.05.2017 | Universität Basel
NASA's SDO sees partial eclipse in space
29.05.2017 | NASA/Goddard Space Flight Center
The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.
The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
30.05.2017 | Life Sciences
30.05.2017 | Power and Electrical Engineering
29.05.2017 | Earth Sciences