Molecular gas properties of Q1700-MD94: a massive, main-sequence galaxy at $z\approx 2$

Abstract

We use a combination of new NOrthern Extended Millimeter Array (NOEMA) observations of the pair of [CI] transitions, the CO(7-6) line, and the dust continuum, in addition to ancillary CO(1-0) and CO(3-2) data, to study the molecular gas properties of Q1700-MD94, a massive, main-sequence galaxy at $z\approx 2$. We find that for a reasonable set of assumptions for a typical massive star-forming galaxy, the CO(1-0), the [CI](1-0) and the dust continuum yield molecular gas masses that are consistent within a factor of $\sim 2$. The global excitation properties of the molecular gas as traced by the [CI] and CO transitions are similar to those observed in other massive, star-forming galaxies at $z\sim 2$. Our large velocity gradient (LVG) modeling using RADEX of the CO and [CI] spectral line energy distributions (SLEDs) suggests the presence of relatively warm ($T_{\mathrm{kin}}=41$K), dense ($n_{{\mathrm{H}}_2}=8\times 10^3{\mathrm{cm}}^{-3}$) molecular gas, comparable to the high-excitation molecular gas component observed in main-sequence, star-forming galaxies at $z\sim 1$. The galaxy size in the CO(1-0) and CO(7-6) line emission are comparable, which suggests that the highly-excited molecular gas is distributed throughout the disk powered by intense star formation activity. To confirm this scenario will require spatially resolved observations of the CO and [CI] lines which can now be obtained with NOEMA upgraded capabilities.

7 pages, 4 figures, accepted for publication in A&A as a Letter to the Editor

References in corpus (15)

• Combined CO & Dust Scaling Relations of Depletion Time and Molecular Gas Fractions with Cosmic Time, Specific Star Formation Rate and Stellar Mass
• H-alpha Observations of a Large Sample of Galaxies at z~2: Implications for Star Formation in High Redshift Galaxies
• CO excitation of normal star forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium
• Dust temperature and mid-to-total infrared color distributions for star-forming galaxies at 0<z<4
• ALMA observations of atomic carbon in z~4 dusty star-forming galaxies
• Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z~2-4 as probed by multi-J CO lines
• Turbulent Gas in Lensed Planck-selected Starbursts at redshifts 1-3.5
• The properties of the interstellar medium of galaxies across time as traced by the neutral atomic carbon [CI]
• CO(1-0) line imaging of massive star-forming disc galaxies at z=1.5-2.2
• High-J CO SLEDs in nearby infrared bright galaxies observed by Herschel-PACS
• Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A method to determine molecular gas properties in luminous galaxies
• CO emission in distant galaxies on and above the main sequence
• From Nuclear to Circumgalactic: Zooming in on AGN-Driven Outflows at z~2.2 with SINFONI
• [CI](1-0) and [CI](2-1) in resolved local galaxies
• Revisited cold gas content with atomic carbon [C I] in z=2.5 protocluster galaxies

Cited by in corpus (8)

• PDFchem: A new fast method to determine ISM properties and infer environmental parameters using probability distributions
• Jansky Very Large Array detections of CO(1-0) emission in HI-absorption-selected galaxies at $z\gtrsim 2$
• CO Excitation and Line Energy Distributions in Gas-selected Galaxies
• HYACINTH: HYdrogen And Carbon chemistry in the INTerstellar medium in Hydro simulations
• CO Excitation in High-z Main Sequence Analogues: Resolved CO(4-3)/CO(3-2) Line Ratios in DYNAMO Galaxies
• Deep kiloparsec view of the molecular gas in a massive star-forming galaxy at cosmic noon
• Molecular gas content and high excitation of a massive main-sequence galaxy at z = 3
• Molecular gas budget of strongly magnified low-mass star-forming galaxies at cosmic noon