eprintid: 10093776 rev_number: 15 eprint_status: archive userid: 608 dir: disk0/10/09/37/76 datestamp: 2020-04-27 15:13:43 lastmod: 2021-10-01 23:52:10 status_changed: 2020-04-27 15:13:43 type: article metadata_visibility: show creators_name: Schirm, MRP creators_name: Wilson, CD creators_name: Parkin, TJ creators_name: Kamenetzky, J creators_name: Glenn, J creators_name: Rangwala, N creators_name: Spinoglio, L creators_name: Pereira-Santaella, M creators_name: Baes, M creators_name: Barlow, MJ creators_name: Clements, DL creators_name: Cooray, A creators_name: De Looze, I creators_name: Karczewski, OL creators_name: Madden, SC creators_name: Rémy-Ruyer, A creators_name: Wu, R title: Herschel-SPIRE Fourier Transform Spectrometer observations of excited CO and [C I] in the Antennae (NGC 4038/39): warm and cold molecular gas ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F60 keywords: galaxies: individual (NGC 4038, NGC 4039), galaxies: interactions, infrared: galaxies, ISM: molecules, submillimeter: galaxies note: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. abstract: We present Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) observations of the Antennae (NGC 4038/39), a well-studied, nearby (22 Mpc), ongoing merger between two gas-rich spiral galaxies. The SPIRE-FTS is a low spatial ( FWHM ~ 19''-43'') and spectral (~1.2 GHz) resolution mapping spectrometer covering a large spectral range (194-671 μm, 450-1545 GHz). We detect five CO transitions (J = 4-3 to J = 8-7), both [C I] transitions, and the [N II] 205 μm transition across the entire system, which we supplement with ground-based observations of the CO J = 1-0, J = 2-1, and J = 3-2 transitions and Herschel Photodetecting Array Camera and Spectrometer (PACS) observations of [C II] and [O I] 63 μm. Using the CO and [C I] transitions, we perform both a local thermodynamic equilibrium (LTE) analysis of [C I] and a non-LTE radiative transfer analysis of CO and [C I] using the radiative transfer code RADEX along with a Bayesian likelihood analysis. We find that there are two components to the molecular gas: a cold (T kin ~ 10-30 K) and a warm (T kin gsim 100 K) component. By comparing the warm gas mass to previously observed values, we determine a CO abundance in the warm gas of x CO ~ 5 × 10–5. If the CO abundance is the same in the warm and cold gas phases, this abundance corresponds to a CO J = 1-0 luminosity-to-mass conversion factor of αCO ~ 7 M ☉ pc–2 (K km s–1)–1 in the cold component, similar to the value for normal spiral galaxies. We estimate the cooling from H2, [C II], CO, and [O I] 63 μm to be ~0.01 L ☉/M ☉. We compare photon-dominated region models to the ratio of the flux of various CO transitions, along with the ratio of the CO flux to the far-infrared flux in NGC 4038, NGC 4039, and the overlap region. We find that the densities recovered from our non-LTE analysis are consistent with a background far-ultraviolet field of strength G 0 ~ 1000. Finally, we find that a combination of turbulent heating, due to the ongoing merger, and supernova and stellar winds are sufficient to heat the molecular gas. date: 2014-02-01 date_type: published official_url: https://doi.org/10.1088/0004-637X/781/2/101 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 926989 doi: 10.1088/0004-637X/781/2/101 lyricists_name: Barlow, Michael lyricists_id: MJBAR75 actors_name: Barlow, Michael actors_id: MJBAR75 actors_role: owner full_text_status: public publication: The Astrophysical Journal volume: 781 number: 2 article_number: 101 citation: Schirm, MRP; Wilson, CD; Parkin, TJ; Kamenetzky, J; Glenn, J; Rangwala, N; Spinoglio, L; ... Wu, R; + view all <#> Schirm, MRP; Wilson, CD; Parkin, TJ; Kamenetzky, J; Glenn, J; Rangwala, N; Spinoglio, L; Pereira-Santaella, M; Baes, M; Barlow, MJ; Clements, DL; Cooray, A; De Looze, I; Karczewski, OL; Madden, SC; Rémy-Ruyer, A; Wu, R; - view fewer <#> (2014) Herschel-SPIRE Fourier Transform Spectrometer observations of excited CO and [C I] in the Antennae (NGC 4038/39): warm and cold molecular gas. The Astrophysical Journal , 781 (2) , Article 101. 10.1088/0004-637X/781/2/101 <https://doi.org/10.1088/0004-637X%2F781%2F2%2F101>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10093776/1/schirm2013_1312.2522.pdf