Hubble discovers thousands of globular clusters scattered among galaxies

The survey, published in the November 9, 2018 issue Astrophysical Journal, will allow astronomers to use the globular globule field to map the distribution of matter and dark matter in clusters of Coma galaxies, which contain more than 1,000 packed galaxies.

Because globular clusters are much smaller than whole galaxies – and much more abundant – they trace much better how the tissue of space is deformed by the gravity of the Coma cluster. In fact, Coma's group is one of the first places where the observed gravitational anomalies were considered to reveal an invisible mass in the universe, later called "dark matter".

Among the first homesteaders in the universe, globular star clusters are globe – shaped snow islands of several hundred thousand ancient stars. They are an integral part of the birth and growth of a galaxy. About 150 globular groups slipped around our Milky Way galaxy and, because they contain the oldest known stars of the universe, were present in the early forming years of our galaxy.

Some of the globular clusters of the Milky Way are visible to the naked eye in the form of "blurred" stars. But at a distance from Coma's group, his globulars appear as points of light, even for Hubble's clear vision. The investigation revealed globular clusters dispersed in the space between galaxies. They are orphaned from their original galaxy because of near-collisions inside the traffic-jammed cluster. Hubble revealed that some globular clusters align along bridge-like patterns. This is the revealing proof of the interactions between galaxies where they shoot each other gravelly against each other as if they were shooting.

The astronomer Juan Madrid of the Australian Telescope National Facility in Sydney, Australia, first thought about the distribution of globular clusters in Coma when he was examining Hubble images showing globular clusters. stretching to the edge of a galaxy photograph in Coma. cluster.

He looked forward to receiving more data from one of Hubble's previous surveys, designed to obtain data on the entire Coma cluster, called the Coma Cluster Treasury Survey. However, halfway through the program, in 2006, Hubble's powerful Hubble Camera (ACS) had suffered an electronic failure. (The ACS was later repaired by astronauts during a Hubble maintenance mission in 2009.)

To fill in the gaps in the investigation, Madrid and his team have painstakingly drawn numerous images of Hubble's cluster of galaxies from Hubble's various observing programs. These are stored in the Mikulski Archive for Space Telescopes of the Space Telescope Scientific Institute in Baltimore, Maryland. He assembled a mosaic of the Central Area of ​​the cluster, in collaboration with students from the National Science Foundation's Undergraduate Research Experience program. "This program offers students enrolled in little or no astronomical universities to gain experience in the field," Madrid said.

The team developed algorithms to screen images of the Coma mosaic containing at least 100,000 potential sources. The program used the color of globular clusters (dominated by the glow of aging red stars) and their spherical shape to eliminate superfluous objects, mainly background galaxies not associated with clusters. Coma.

Although Hubble has superb detectors with unparalleled sensitivity and resolution, their main drawback is that they have tiny fields of view. "One of the interesting aspects of our research is that it presents the amazing science that will be possible with NASA's future wide-field infrared surveyor telescope (WFIRST), which will have a field of vision much wider than Hubble, "said Madrid. "We will be able to image clusters of whole galaxies at a time."

Explore further:
Image: Hubble surprises galaxies invaded by star clusters

More information:
Juan P. Madrid et al. A large-field map of intracluster global clusters in coma, The astrophysical journal (2018). DOI: 10.3847 / 1538-4357 / aae206