I mean, I included a disclaimer... But regardless, you appear to be wrong on both counts (or at least contradicting Wikipedia):

1. "The presence of a black hole can be inferred through its interaction with OTHER MATTER and with electromagnetic radiation such as visible light." https://en.wikipedia.org/wiki/Black_hole

2. "A dwarf galaxy is a small galaxy composed of ABOUT 1000 up to several billion stars" https://en.wikipedia.org/wiki/Dwarf_galaxy

Darn astrophysics majors being confident about astronomy! ;)