Question: What us the brightest qazar/blazar to exist? How many suns in brightness is it? (Does this question make sense?)

Miranda Jackson answered on 15 Jun 2015:

Blazars and quasars are entire galaxies that are sometimes not very easy to detect or see only because they are so far away. As galaxies, they are the same mass as about a trillion (1 000 000 000 000) suns, but normal galaxies are only as bright as 10 billion suns. Active galaxies such as blazars and quazars release a lot of energy from the black hole at their core, and this overpowers the starlight by a factor of 10 or 100, so that they could be as bright as a 100 billion or several trillion suns. However, because they are so far away, they appear only as bright as an ordinary single nearby star. The quasar 3C 273 is the brightest quasar in our sky, with the same brightness as 4 trillion suns, but it requires a telescope to see it, but another quasar, known as ULAS J1120+0641, is much brighter, with a brightness equal to 63 trillion suns, but because it is the farthest object ever found, it can only be detected by the most sensitive telescopes. A few other quasars are estimated to be 100 times brighter then even that one.