ALMA Reveals a Gas-rich, Maximum Starburst in the Hyperluminous, Dust-obscured Quasar W0533–3401 at z ∼ 2.9

Abstract

Abstract We present ALMA observations and multiwavelength spectral energy distribution analysis in a Wide-field Infrared Survey Explorer-selected, hyperluminous dust-obscured quasar W0533−3401 at z = 2.9. We derive the physical properties of each of its components, such as molecular gas, stars, dust, and the central supermassive black hole (SMBH). Both the dust continuum at 3 mm and the CO line are detected. The derived molecular gas mass M gas = 8.4 × 1010 M ⊙ and its fraction f gas = 0.7 suggest that W0533−3401 is gas-rich. The star formation rate (SFR) has been estimated to be ∼3000–7000 M ⊙ yr−1 by using different methods. The high values of SFR and specific SFR suggest that W0533−3401 is a maximum starburst. The corresponding gas depletion timescales are very short (t depl ∼ 12–28 Myr). The CO emission line is marginally resolved and has a velocity gradient, which is possibly due to a rotating gas disk, gas outflow, or merger. Finally, we infer the black hole mass growth rate of W0533−3401 ( M ⊙ yr−1), which suggests a rapid growth of the central SMBH. The observed black hole to stellar mass ratio M BH/M ⋆ of W0533−3401, which is dependent on the adopted Eddington ratio, is over one order of magnitude higher than the local value, and is evolving toward the evolutionary trend of unobscured quasars. Our results are consistent with the scenario that W0533−3401, with both a gas-rich maximum starburst and a rapid black hole growth, is experiencing a short transition phase toward an unobscured quasar.