The distant quasar ULAS J1120+0641 has a luminosity 6 × 10¹³ L_e. Assuming it is at its Eddington limit, what is its mass (in solar masses)? A)30,000 B)2 million C)2 billion D)6 billion

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Quizplus · Accepted Answer

The Eddington limit gives the maximum luminosity a black hole can have for a given mass. Assuming the quasar is at its Eddington limit, we can use the formula L = 4πGMm_p c/ σ_T to solve for the mass (where L is the luminosity, G is the gravitational constant, M is the mass of the black hole, m_p is the mass of a proton, c is the speed of light, and σ_T is the Thomson scattering cross-section). Rearranging the formula, we get M = L(c/4πGm_p σ_T), and plugging in the given values, we get M = 2 billion solar masses.

The Distant Quasar ULAS J1120+0641 Has a Luminosity 6 ×