Let's assume that the Bubbles are due to radiation emanating from material falling into our central black hole, which we'll further assume occurred at a constant rate.

(a) Estimate the rate of mass accretion onto the black hole to create the Bubbles in solar masses per year.

(b) Assuming constant mass accretion, how long would it take to build the 4 106 M black hole in the Galactic Center? Compare this to the age of the Universe (14 Gyr), do you think that this rate of accretion could be constant over the lifetime of our central black hole?