Escape, Accretion, or Star Formation? The Competing Depleters of Gas in the Quasar Markarian 231

Abstract

We report on high resolution CO(1–0), CS(2–1), and 3 mm continuum Combined Array for Research in Millimeter Astronomy (CARMA) observations of the molecular outflow host and nearest quasar Markarian 231. We use the CS(2–1) measurements to derive a dense gas mass within Mrk 231 of 1.8 ± 0.3 x 10^(10) M⊙, consistent with previous measurements. The CS(2–1) data also seem to indicate that the molecular disk of Mrk 231 is forming stars at about normal efficiency. The high resolution CARMA observations were able to resolve the CO(1–0) outflow into two distinct lobes, allowing for a size estimate to be made and further constraining the molecular outflow dynamical time, further constraining the molecular gas escape rate. We find that 15% of the molecular gas within the Mrk 231 outflow actually exceeds the escape velocity in the central kiloparsec. Assuming that molecular gas is not constantly being accelerated, we find the depletion timescale of molecular gas in Mrk 231 to be 49 Myr, rather than 32 Myr, more consistent with the poststarburst stellar population observed in the system.

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