The Galaxy Dragonfly 44, which in August 2016 was said to be 99.99% dark matter, it actually has a conformation that “is neither unique nor anomalous”, according to a study by an international team of astronomers.
As reported on Tuesday by the Instituto de Astrofísica de Canarias (IAC), which together with the University of La Laguna (ULL) has participated in the work, this has been led by the Kapteyn Astronomical Institute from the University of Groningen (Netherlands).
Astronomers note that the total number of globular clusters around Dragonfly 44, and thus the dark matter content, is much lower than previous findings suggested. The study has been published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS), it is indicated in a statement in which it is noted that the formation of galaxies cannot be understood without the presence of an omnipresent, but still mysterious component, called dark matter.
Astronomers have measured the amount of dark matter around galaxies and found that varies between 10 and 300 times the amount of visible mass. But with the discovery of Dragonfly 44, in the constellation Coma Berenices, that perspective was altered and that galaxy was said to have 10,000 times more dark matter than stars.
La galaxia Dragonfly 44 was discovered by means of a deep mapping of the Coma cluster, a region of the sky with a grouping of several thousand galaxies. From the beginning, the object caught the attention of researchers because the amount of inferred dark matter was almost as large as the measurement in the Milky Way, the equivalent of a trillion suns.
But, instead of having around one hundred billion stars, as is the case of the Milky Way, DF44 only has one hundred million stars, that is, a thousand times fewer, which led to say that the dark matter content was ten thousand times greater than its stellar content. If it was true I would have made it a unique object, with almost 100 times more dark matter than expected for the number of stars it has.
But now, using a comprehensive analysis of the globular cluster system around Dragonfly 44, researchers have found that the total number of globular clusters is 20 and that the total amount of dark matter in the system is about 300 times the luminous mass, which makes the object was the expected for this type of galaxy.
“Dragonfly 44 has been an anomaly all these years that could not be explained with existing galaxy formation models. We now know that previous results were wrong and that DF44 is not extraordinary. It’s time to move on, “says Teymoor Saifollahi, a researcher at the Kapteyn Astronomical Institute and lead author of the study.
“Our work shows that this galaxy it is not so unique or unusual. In this way, the galaxy formation model is able to explain it without the need to modify it “, points out Michael A. Beasley, also a researcher at the IAC and co-author of the article.
He adds that it is a purely observational fact, “although it may have to do with the amount of initial gas that forms the stars and the globular clusters themselves”, since “the more dark matter there is in a galaxy, the more gas is also has, “he warns.