The puzzle of the galaxy with no dark matter

A staff of scientists, led by the researcher on the IAC and the College of La Laguna (ULL) Sebastién Comerón, has discovered that the galaxy NGC 1277 doesn’t include dark matter. That is the primary time {that a} large galaxy (it has a mass a number of instances that of the Milky Way) has not proven proof for this invisible part of the universe. “This end result doesn’t slot in with the presently accepted cosmological fashions, which embrace dark matter,” explains Comerón.

Within the present standard model cosmology massive galaxies include substantial portions of dark matter, a kind of matter which doesn’t work together in the identical method as regular matter; the one proof for its existence is the sturdy gravitational pull which it exerts on the celebrities and the fuel close by, and this interacton is observable.

NGC 1277 is taken into account a prototype “relic galaxy” which suggests a galaxy which has had no interactions with its neighbors. Galaxies of this kind are very uncommon, and they’re thought of the remnants of large galaxies which shaped within the early days of the universe.

“The significance of relic galaxies in serving to us to know how the primary galaxies shaped was the explanation we determined to look at NGC 1277 with an integral discipline spectrograph,” explains Comerón. “From the spectra we made kinematic maps which enabled us to work out the distribution of mass inside the galaxy out to a radius of some 20,000 mild years,” he says.

The staff found that the mass distribution in NGC 1277 was simply the distribution of the celebrities, and from this they inferred that inside the radius noticed there can’t be greater than 5% of dark matter, though the observations are according to the entire absence of this part.

Nevertheless, current cosmological fashions predict {that a} galaxy with the mass of NGC 1277 ought to have no less than 10 % of its mass within the type of dark matter, with a most of 70 % on this kind. “This discrepancy between the observations and what we might count on is a puzzle, and possibly even a problem for the usual mannequin,” notes Ignacio Trujillo, a researcher on the IAC and the ULL, who participated within the research.

The article suggests two attainable explanations for the shortage of dark matter in NGC 1277. “One is that the gravitational interplay with the encompassing medium inside the galaxy cluster wherein this galaxy is located has stripped out the dark matter,” feedback Anna Ferré-Mateu, a researcher on the IAC and the ULL who additionally participated within the research. “The opposite is that the dark matter was pushed out of the system when the galaxy shaped by the merging of protogalactic fragments, which gave rise to the relic galaxy.”

For the authors of the research neither of those explanations is absolutely passable, “so the puzzle of how a massive galaxy can kind with out dark matter stays a puzzle,” insists Comerón. As a way to proceed researching the thriller the staff plans to make new observations with the WEAVE instrument on the William Herschel Telescope (WHT) on the Roque de los Muchachos Observatory, on the Canary Island of La Palma

If this end result—that NGC 1277 doesn’t have dark matter—is confirmed, it could solid sturdy doubt on various fashions for dark matter, specifically theories wherein gravity is modified and the foremost a part of the gravitational attraction inside galaxies is because of a slight change within the legislation of gravity on massive scales. “Though the dark matter in a selected galaxy might be misplaced, a modified legislation of gravity have to be common, it can not have exceptions, so {that a} galaxy with out dark matter is a refutation of the sort of various to dark matter,” notes Trujillo.

The findings are printed within the journal Astronomy & Astrophysics.