Herschel-SPIRE Fourier transform spectroscopy of the nearby spiral galaxy IC 342★

Rigopoulou, D.; Hurley, P. D.; Swinyard, B. M.; Virdee, J. S.; Croxall, K. V.; Hopwood, R.; Lim, T.; Magdis, G.; Pearson, Chris; Pellegrini, E.; Polehampton, E. T.; Smith, J. D.

doi:10.1093/mnras/stt1149

Cited by 40 publications

(53 citation statements)

References 51 publications

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“…We tried to fit CO ladders in the central 45 with a single LVG component first, however, it does not produce a good fit. This is not surprising since the modeling results in previous studies (e.g., Kamenetzky et al 2012;Hailey-Dunsheath et al 2012;Rigopoulou et al 2013) have shown that the coexistence of multiple excitation gas components in nearby galaxies (also see Lu et al 2014). Therefore, we use two LVG components to model the gas excitation in the central 45 region.…”

Section: Two-component Modeling In the Central 45 Regionmentioning

confidence: 58%

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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We report mapping observations of the 12 CO J = 3 → 2, 4 → 3, 6 → 5, and 7 → 6 transitions and the C i 3 P 1 → 3 P 0 (C i) 492 GHz transition toward the central 40 ×40 region of the Circinus galaxy, using the Atacama Pathfinder EXperiment (APEX) telescope. We also detected 13 CO J = 3 → 2 at the central position of Circinus. These observations are to date the highest CO transitions reported in Circinus. With large velocity gradient (LVG) modeling and likelihood analysis we try to obtain density, temperature, and column density of the molecular gas in three regions: the nuclear region (D < 18 ∼ 360 pc), the entire central 45 (D < 45 ∼ 900 pc) region, and the star-forming (S-F) ring (18 < D < 45 ). In the nuclear region, we can fit the CO excitation with a single excitation component, yielding an average condition of n H 2 ∼ 10 3.2 cm −3 , T kin ∼ 200 K, and d /dr ∼ 3 km s −1 pc −1 . In the entire 45 region, which covers both the nucleus and the S-F ring, two excitation components are needed with n H 2 ∼ 10 4.2 cm −3 and 10 3.0 cm −3 , T kin ∼ 60 K and 30 K, and M H 2 ∼ 2.3 × 10 7 M and 6.6 × 10 7 M , respectively. The gas excitation in the S-F ring can also be fitted with two LVG components, after subtracting the CO fluxes in the 18 nuclear region. The S-F ring region contributes 80% of the molecular mass in the 45 region. For the entire 45 region, we find a standard conversion factor of N(H 2 )/I CO 1→0 = 0.37 × 10 20 cm −2 (K km s −1 ) −1 , about 1/5 of the Galactic disk value. The luminosity ratios of C i and 12 CO J = 3 → 2 (R CI/CO 3→2 ) in Circinus basically follow a linear trend, similar to that obtained in high-redshift galaxies. The average R CI/CO J = 3 → 2 in Circinus is found to be ∼0.2, lying at an intermediate value between non-AGN nuclear regions and high-redshift galaxies.

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Section: Two-component Modeling In the Central 45 Regionmentioning

confidence: 58%

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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“…We determined the aperture correction of the Herschel CO[5-4] measurements using the IRAS imaging. In addition, we used data for the local spiral IC 342 from Rigopoulou et al (2013) and the MW.…”

Section: Comparison Samples Of Local Spirals and (U)lirgsmentioning

confidence: 99%

CO excitation of normal star-forming galaxies out toz= 1.5 as regulated by the properties of their interstellar medium

Daddi

Dannerbauer

Liu

et al. 2015

A&A

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We investigate the CO excitation of normal (near-IR selected BzK) star-forming (SF) disk galaxies at z = 1.5 using IRAM Plateau de Bure observations of the CO[2-1], CO , and CO[5-4] transitions for four galaxies, including VLA observations of CO[1-0] for three of them, with the aim of constraining the average state of H 2 gas. By exploiting previous knowledge of the velocity range, spatial extent, and size of the CO emission, we measure reliable line fluxes with a signal-to-noise ratio >4-7 for individual transitions. While the average CO spectral line energy distribution (SLED) has a subthermal excitation similar to the Milky Way (MW) up to CO[3-2], we show that the average CO emission is four times stronger than assuming MW excitation. This demonstrates that there is an additional component of more excited, denser, and possibly warmer molecular gas. The ratio of CO[5-4] to lower-J CO emission is lower than in local (ultra-)luminous infrared galaxies (ULIRGs) and high-redshift starbursting submillimeter galaxies, however, and appears to be closely correlated with the average intensity of the radiation field U and with the star formation surface density, but not with the star formation efficiency. The luminosity of the CO transition is found to be linearly correlated with the bolometric infrared luminosity over four orders of magnitudes. For this transition, z = 1.5 BzK galaxies follow the same linear trend as local spirals and (U)LIRGs and high-redshift star-bursting submillimeter galaxies. The CO[5-4] luminosity is thus empirically related to the dense gas and might be a more convenient way to probe it than standard high-density tracers that are much fainter than CO. We see excitation variations among our sample galaxies that can be linked to their evolutionary state and clumpiness in optical rest-frame images. In one galaxy we see spatially resolved excitation variations, where the more highly excited part of the galaxy corresponds to the location of massive SF clumps. This provides support to models that suggest that giant clumps are the main source of the high-excitation CO emission in high-redshift disk-like galaxies.

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“…18. L CO /L TIR as a function of L TIR for various extragalactic sources: NGC 6240 (Meijerink et al 2013), NGC 1266 (Pellegrini et al 2013), M83 (Wu et al 2015b), Arp 220 (Rangwala et al 2011), M82 (Kamenetzky et al 2012), Mrk 231 (van der Werf et al 2010, and IC 342 (Rigopoulou et al 2013). The sources are color coded based on the dominant heating mechanism: UV photons (red), X-rays (purple), and mechanical heating (blue).…”

Section: Origin Of Shocksmentioning

confidence: 99%

Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud

Lee

Madden

Lebouteiller

et al. 2016

A&A

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We present Herschel SPIRE Fourier Transform Spectrometer (FTS) observations of N159W, an active star-forming region in the Large Magellanic Cloud (LMC). In our observations, a number of far-infrared cooling lines including CO J = 4 → 3 to J = 12 → 11, [CI] 609 µm and 370 µm, and [NII] 205 µm are clearly detected. With an aim of investigating the physical conditions and excitation processes of molecular gas, we first construct CO spectral line energy distributions (SLEDs) on ∼10 pc scales by combining the FTS CO transitions with ground-based low-J CO data and analyze the observed CO SLEDs using non-LTE radiative transfer models. We find that the CO-traced molecular gas in N159W is warm (kinetic temperature of 153-754 K) and moderately dense (H 2 number density of (1.1-4.5) × 10 3 cm −3 ). To assess the impact of the energetic processes in the interstellar medium on the physical conditions of the CO-emitting gas, we then compare the observed CO line intensities with the models of photodissociation regions (PDRs) and shocks. We first constrain the properties of PDRs by modelling Herschel observations of [OI] 145 µm, [CII] 158 µm, and [CI] 370 µm fine-structure lines and find that the constrained PDR components emit very weak CO emission. X-rays and cosmic-rays are also found to provide a negligible contribution to the CO emission, essentially ruling out ionizing sources (ultraviolet photons, X-rays, and cosmic-rays) as the dominant heating source for CO in N159W. On the other hand, mechanical heating by low-velocity C-type shocks with ∼10 km s −1 appears sufficient enough to reproduce the observed warm CO.

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Herschel-SPIRE Fourier transform spectroscopy of the nearby spiral galaxy IC 342★

Cited by 40 publications

References 51 publications

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

CO excitation of normal star-forming galaxies out toz= 1.5 as regulated by the properties of their interstellar medium

Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud

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Herschel-SPIRE Fourier transform spectroscopy of the nearby spiral galaxy IC 342★

Cited by 40 publications

References 51 publications

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

CO excitation of normal star-forming galaxies out toz= 1.5 as regulated by the properties of their interstellar medium

Radiative and mechanical feedback into the molecular gas in the Large Magellanic Cloud

Contact Info

Product

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Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations