The "Teacup Galaxy" (SDSS J1430+1339) is an active galaxy containing a "fossil quasar"—a region of gas still glowing from a highly energetic quasar phase that has recently ended.
Explain what powers a quasar, and suggest why this quasar has ceased to emit high-energy radiation.
Spectral analysis of the Teacup Galaxy shows a redshift of z=0.0480z = 0.0480z=0.0480.
Determine the distance from Earth to this galaxy, stating an appropriate unit.
(Take the Hubble constant to be H0=72 km s−1 Mpc−1H_0 = 72\text{ km s}^{-1}\text{ Mpc}^{-1}H0=72 km s−1 Mpc−1 and the speed of light to be c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1.)
