Dark Matter Point Sources Outside Galaxies the extra origin of gravity lenses and UDGs Ultra Diffuse Galaxy forming in Clusters.

Hubble telescope found strong evidence of individual gravity lenses oustside Galaxies in clusters. see: Hubble image of galaxy cluster MACS J1206 https://spacetelescope.org/images/heic1115a/

"This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J1206. Galaxy clusters like these have enormous mass, and their gravity is powerful enough to visibly bend the path of light, somewhat like a magnifying glass.

These clusters are useful tools for studying very distant objects, because this lens-like behaviour amplifies the light from faraway galaxies in the background. They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime, the expansion of the cosmos and the distribution of dark matter within the cluster.

This is one of 25 clusters being studied as part of the CLASH (Cluster Lensing and Supernova survey with Hubble) programme, a major project to build a library of scientific data on lensing clusters.  Credit: NASA, ESA, M. Postman (STScI) and the CLASH Team. "

see also: https://bigbang-entanglement.blogspot.com/2016/07/the-mystery-of-cool-corusus-of-galaxy.html

and: https://www.sciencedaily.com/releases/2020/09/200910150348.htm

According to Q-FFF Theory, Around each galaxy there should be so called primary dual black holes, as the remnant of the former Herbig Haro ( bow shock/ black hole) system.  The origin is also called External Galaxy Anchor Black Holes or Dark Matter Point sources, responsible for strong gravity lenses and UDGs.       (below)

see also: https://www.researchgate.net/publication/319250867_The_Origin_of_Ultra_Diffuse_Galaxies_in_Galaxy_Cluster_Centers/figures

below, UDGs in the Coma cluster.  the Black Holes are in this photo, not observed directly or by gravitational lensing.!

Next Book, the New String Black Holes