Merging galaxy baffles scientists
A new study has pointed to previously unseen behaviour by
concentrations of dark and visible matter in the formation of a merging
galaxy cluster 2.4 billion light-years away. Scientists were baffled by
the merging galaxy cluster known as Abell 520, where concentrations of
visible matter and dark matter - the invisible substance that makes up
much of our universe - have apparently come unglued.
This composite image shows the distribution of dark matter,
galaxies, and hot gas in the core of the merging galaxy cluster
Abell 520, formed from a violent collision of massive galaxy
The findings of the observations, which were made using the NASA's
Hubble Space Telescope, were published in a report in the Astrophysical
“We were not expecting this,” the study team's senior theorist, Arif
Babul of the University of Victoria, said in a news release.
“According to our current theory, galaxies and dark matter are
expected to stay together, even through a collision. But that's not
what's happening in Abell 520. Here, the dark matter appears to have
pooled to form the dark core, but most of the associated galaxies seem
to have moved on,” he added.
Observations like those of Abell 520 are humbling in the sense that
in spite of all the leaps and bounds in our understanding, every now and
then, we are stopped cold,” Babul explained.
Astronomer James Jee, a project scientist in the Department of
Physics at UC Davis, said, “This result is a puzzle… Dark matter is not
behaving as predicted, and it's not obviously clear what is going on.
Theories of galaxy formation and dark matter must explain what we are
The dark matter was first detected in 2007 during a survey aimed at
measuring the masses of 50 galaxy clusters thanks to data from the
Canada-France-Hawaii Telescope at Mauna Kea in Hawaii.
New study has revealed that ancient manuscripts written by Arab
scholars can provide significant meteorological information for modern
Spanish scientists from the Universidad de Extremadura have turned to
Arabic documentary sources from the 9th and 10th centuries to get meteo
The sources, penned by historians and political commentators of the
era, focus on the social and religious events of the time, but do refer
to abnormal weather events as well.
Analyzing writings of scholars, historians and diarists during the
Islamic Golden Age (816-1009 CE) of Iraq has helped meteo scientists
reconstruct climate pattern of the past.
“Climate information recovered from these ancient sources mainly
refers to extreme events which impacted wider society such as droughts
and floods,” said lead author Dr. Fernando Dominguez-Castro.
The documents also mentioned the conditions, which rarely occurred in
ancient Baghdad such as hailstorms, the freezing of rivers or even cases
of snow, he added.
The manuscripts revealed an increase in cold weather in the first
half of the 10th century, a significant drop of temperature during July
920 CE and three separate recordings of snowfall in 908, 944 and 1007,
exactly before the Medieval Warm Period.
“Ancient Arabic documentary sources are a very useful tool for
finding eye witness descriptions which support the theories made by
climate models,” said Dominguez-Castro.