The phrase
"galaxy masses" refers to the amount of matter contained within a galaxy. It represents how much stuff, like stars, gas, and dust, exists in a particular galaxy.
Full definition
The mass of each black hole is roughly proportional to the mass of the galaxy itself, and makes up approximately half a percent of the
total galaxy mass.
This provides an independent test for astronomers» usual methods of estimating
distant galaxy masses — which rely on extrapolation from their nearby cousins.
Finally, we compare our results to a previous study using low redshift lenses, to understand
how galaxy mass profiles evolve over time.
Because we can't weigh a galaxy directly, one proxy used
for galaxy mass is its circular velocity; the more massive a galaxy, the faster gas and stars rotate around its center.
Since the number of stars and their mass
influence galaxy mass, the researchers became suspicious that the supermassive black hole and its quasar have reduced star formation, at least in certain neighborhoods of the galaxy.
The result was so surprising, two of the astronomers had to verify
the galaxy mass independently.
Today, neighboring galaxies show that
the galaxy mass is tightly correlated with the supermassive black hole mass.