Accretion Power An astronomer is monitoring the activity in a pair of QSOs. Base

Question

Accretion Power An astronomer is monitoring the activity in a pair of QSOs. Based on their respective redshifts, the astronomer determines that QSO B is at a distance from Earth three times greater than QSO A (i.e. ds = 3 times d_A)- Both QSOs have the same apparent brightness, i.e. flux. The astronomer also determines that QSO A is accreting mass onto its central black hole at a rate of Delta m/Delta t = 0.5 M_sun/year. What are the accretion rate (in M_sun/year) and luminosity (in Joules/sec) of QSO B?

Explanation / Answer

we know, Intensity is inversly proportional to d.

so,

accreation rate of QSO_B = 9*QSO_A

= 9*0.5*Msun/year

= 4.5 M_sun/Year

luminosity = Energy radited/time

= 4.5*M_sun*c^2/year

= 4.5*1.99*10^30*(3*10^8)^2/(365*24*60*60)

= 2.55*10^40 J/s

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