A major discovery that was incompatible with our current theories of dark matter and galaxy formation may have just been resolved.
According to a new analysis, astronomers have discovered that NGC1052-DF2 – which contained absolutely no dark matter last year – is much closer to us than previously thought. Which means that there is probably dark matter.
Dark matter is a big question mark over the universe. We do not know what it is, and we can not see it directly, but we know that there is something that produces the same effect as the mass in the Universe.
For example, objects in galaxies move faster than they should, based on the mass we can directly detect; An undetectable force-dark matter, if you will-creates more gravity than we can explain with normal matter.
This stuff is fundamental to our understanding of the universe. We believe that stars and galaxies have helped form the original soup that existed just after the Big Bang, and that it helps keep stuff in galaxies from simply flying into space.
And our model of galaxy formation depends on it. [1
"Then everything else happens: gas falls into the halos of dark matter, the gas turns into stars, they slowly build up, and in the end, galaxies like the Milky Way come into existence." NGC1052-DF2 questions the common ideas about the origin of galaxies. "
Dark matter therefore seems to be one In fact, until the discovery of NGC1052-DF2, each galaxy seemed to have at least some. In fact, most people seem to have more dark matter than normal matter.
An international research team led by the Instituto de Astrofísica de Canarias (IAC) decided to take a closer look. And they found that all anomalous measurements in previous research that pointed to the absence of dark matter depended on the distance to the galaxy-64 million light-years away.
This gave them something to work with. Using five separate methods, including the Hubble Space Telescope and Gemini Observatory photometry, they recalculated the distance to NGC1052-DF2.
Each method delivered the same result – NGC1052-DF2 is far closer than 64 million light-years away. According to several calculations of the team, a more accurate distance would be about 42 million light-years.
Based on this new distance, the mass of the galaxy equals about half the mass previously assumed – and the mass of stars is only about a quarter of what the previous analysis suggested.
The galaxy itself not only has less mass, but the proportion of normal matter in this mass is lower. This implies that the rest must be made of dark matter – you guessed it.
In addition to the calculations, the lack of dark matter was previously derived on the basis of the slow motion of star clusters within the galaxy. With overall lower mass in the galaxy, this movement speed is actually pretty normal.
"With this revised distance," the researchers wrote in their work, "the galaxy seems to be a more ordinary galaxy with low surface brightness and plenty of space for dark matter."
Well, this is not the end of the story , We still need to find out if a similar number problem also affects NGC1052-DF4, a galaxy located about 63 million light-years away near DF2.
Watch this space: Science at work is a beautiful thing after all.
The research was published in the Monthly Notices of the Royal Astronomical Society .