Dark-mat­ter 'de­fi­cient' galaxy found

The find­ing has prompted sci­en­tists to re­con­sider how gal­ax­ies form

All About Space - - Launch Pad -

As­tronomers are scratch­ing their heads af­ter a re­search team dis­cov­ered a galaxy that seems to be devoid of any dark mat­ter. Lo­cated mil­lions of light years away, galaxy NGC-1052-DF2 ap­pears to con­sist en­tirely of or­di­nary mat­ter which, if proven, goes against the the­ory that dark mat­ter should be present wher­ever or­di­nary mat­ter ex­ists.

Most as­tronomers subscribe to the no­tion that roughly 27 per cent of the uni­verse is made up of dark mat­ter, while or­di­nary mat­ter – the stuff we can see – ac­counts for five per cent. The dis­cov­ery – or nondis­cov­ery, if you like – that there is 400-times less dark mat­ter than ex­pected given the size of the galaxy raises the pos­si­bil­ity it is a sep­a­rate ma­te­rial else­where in the uni­verse. It de­fies the idea that the in­ter­ac­tion of stars and gal­ax­ies within dark mat­ter pro­duced the gal­ax­ies we see to­day.

“We thought that ev­ery galaxy had dark mat­ter and that dark mat­ter is how a galaxy be­gins,” ex­plains Pi­eter van Dokkum, Yale’s Sol Gold­man Fam­ily Pro­fes­sor of As­tron­omy. “So find­ing a galaxy with­out it is un­ex­pected. It chal­lenges the stan­dard ideas of how we think gal­ax­ies work, and it shows that dark mat­ter is real. It has its own sep­a­rate ex­is­tence apart from other com­po­nents of gal­ax­ies.

This re­sult also sug­gests that there may be more than one way to form a galaxy.”

The galaxy NGC 1052-DF2 is miss­ing

most, if not all, of its dark mat­ter

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