Search for CO Emission from the Gravitational-Lens System MG 0414+0534 and Its Lensing Galaxy

Abstract

MG 0414+0534 is a gravitational-lens system at z = 2.64 having a steep power-law continuum and an unusually red color in optical light. We searched for redshifted 12CO (J = 3–2) emission from MG 0414+0534 and 12CO (J = 1–0) emission from its lensing galaxy at z = 0.468 using the Nobeyama 45-m radio telescope. No significant emission was detected with a rms noise of 5 mK at a velocity resolution of 20 km s–1. Assuming a velocity width of 400 km s–1, we obtained 3σ upper limits on the molecular gas mass of 1.1 × 1011  h–2  M⊙ for MG 0414+0534 and 5.7 × 1010  h–2  M⊙ for the lensing galaxy (q0 = 0.5, H0 = 100 h km s–1 Mpc–1), adopting a standard Galactic CO-to-H2 conversion factor and neglecting the influence of the lensing event. We examined two views: MG 0414+0534 is a quasar reddened by the interstellar matter in the lensing galaxy or by the interstellar matter surrounding the power-law source.