Could Sgr A* be a core of dark matter instead of a supermassive black hole? A recent paper (related news) shows that Sgr A* at the center of the Milky Way galaxy could be a dark matter core, instead of a supermassive black hole, according to their calculation using the astrometry data of the 17 best-resolved S-stars and the mysterious G2. The dark matter particles could be 56 keV fermions, which they call &quot;darkinos&quot;.
The team also proposes that, above a critical mass, a dark matter clump could gravitationally collapse into a supermassive black hole, like the one in M87.
Is this dark matter model possible? Do the flares from Sgr A* observed in recent years support or contradict this model? Can LHC or other smaller particle colliders or detectors on Earth help to confirm or rule out the particle?
I'm going to say, &quot;probably not&quot;, because (as tfb points out) we have very good evidence for SMBHs in other galaxies -- in particular galaxies with active nuclei where the phenomenon associated with accretion disks around BHs are seen. The most extreme case is probably NGC 4395, where a Seyfert 1 nucleus and associated radio jets exist. The best estimates for accretion-disk+SMBH models suggest a SMBH mass of only a few hundred thousand solar masses; a recent direct dynamical measurement (den Brok et al. 2015) indicate a central &quot;dark object&quot; gravitational mass of $M_{\rm BH} \sim 400,000$ solar masses. There are numerous other galaxies with active nuclei where the estimated or measured central-object masses are $M_{\rm BH} \sim 10^{6}$--$10^{7} M_{\odot}$.
This is rather difficult to square with the claim that &quot;above a critical mass, a dark matter clump could gravitationally collapse into a supermassive black hole&quot; because if you follow up the associated reference to Argüelles et al. (2021), it ends up predicting a critical mass of $\sim 10^{8} M_{\odot}$. This is consistent with something like M87 ($M_{\rm BH} \sim 6 \times 10^{9} M_{\odot}$), but not with all the evidence for accreting SMBHs in galaxy centers with $M_{\rm BH} &lt; 10^{7} M_{\odot}$.
The &quot;flares observed from Sgr A* in recent years&quot; are, I believe, generally supposed to be evidence for a very weak, transient accretion disk around the SMBH (e.g., the discussion on this web page), and so would be difficult to explain with this model.