Remarkably high mass and velocity dispersion of molecular gas associated with a regular, absorption-selected type I quasar

Abstract

We present 3 mm observations of the quasar J0015+1842 at z = 2.63 with the NOrthern Extended Millimeter Array (NOEMA). Our data reveal molecular gas, traced with a Gaussian CO(3–2) line, with a remarkably high velocity dispersion (FWHM = 1010 ± 120 km s−1) that corresponds to a total molecular mass MH2 ≈ (3.4 − 17) × 1010 M⊙, depending on the adopted CO-to-H2 conversion factor αCO = (0.8 − 4.0) M⊙ (km s−1 pc2)−1. Assuming the 3 mm continuum emission is thermal, we derive a dust mass of about Mdust ∼ 5 × 108 M⊙. J0015+1842 is located in the molecular gas-rich region in the IR versus CO line luminosity diagram, in between the main locus of main-sequence and sub-millimetre galaxies and that of most other active galactic nuclei targeted so far for CO measurements. While the high velocity dispersion of the CO line suggests a merging system, J0015+1842 is observed to be a regular, only very moderately dust-reddened (AV ∼ 0.3 − 0.4) type I quasar from its UV-optical spectrum, from which we infer a mass of the super-massive black hole of about MBH ≈ 6 × 108 M⊙. We suggest that J0015+1842 is observed at a galaxy evolutionary stage where a massive merger has brought significant amounts of gas towards an actively accreting super-massive black hole (quasar). While the host still contains a large amount of dust and molecular gas with a high velocity dispersion, the quasar has already cleared the way towards the observer, likely through powerful outflows, as has recently been revealed by optical observations of the same object. High angular resolution observations of this and similar systems are expected to help us better determine the respective importance of evolution and orientation in the appearance of quasars and their host galaxies. These observations have the potential to investigate early feedback and star-formation processes in galaxies in their quasar phases.

Dust and Cold Gas Properties of Starburst HyLIRG Quasars at z ∼ 2.5

“…is adopted. L CO 1 0 ¢ -vs. the CO FWHM (Δ V ) for our sample of six HyLIRG quasars and 180 galaxies from the literature, including lensed and unlensed SMGs and DSFGs (Harris et al 2012;Bothwell et al 2013;Aravena et al 2016;Yang et al 2017;Bakx et al 2020), local/low-to-mid-z ULIRGs (Solomon et al 1997;Combes et al 2006Combes et al , 2011Combes et al , 2013, and high-z quasars and companions (Wang et al 2010;Riechers 2011;Feruglio et al 2017;Fan et al 2018Fan et al , 2019Bischetti et al 2021;Noterdaeme et al 2021). Data points using CO high-J transitions (J 3) are marked with triangles and converted to CO(1-0) using the same factors as in this paper (i.e., Carilli & Walter 2013), while data points using CO J 2 transitions are marked with filled circles.…”

Chemical diversity of gas in distant galaxies

“…It has also been studied in the literature (e.g. Petitjean et al 2002;Ledoux et al 2002b;Rodríguez et al 2006;Noterdaeme et al 2021). Given its relatively high metallicity for a DLA, this system is likely to be associated with a relatively massive galaxy according to the massmetallicity relation in DLAs (Christensen et al 2014), possibly of the order of M * ∼ 10 10 M .…”