Warm Molecular Gas in Luminous Infrared Galaxies

Lu, N.; Zhao, Yi; Xu, C. K.; Gao, Yu; Armus, L.; Mazzarella, J. M.; Isaak, K. G.; Petric, Andreea; Charmandaris, V.; Díaz-Santos, T.; Evans, A. S.; Howell, Justin; Appleton, P. N.; Inami, Hanae; Iwasawa, K.; Leech, J.; Lord, S. D.; Sanders, D. B.; Schulz, B.; Surace, J.; Werf, P. P. van der

doi:10.1088/2041-8205/787/2/l23

Cited by 59 publications

(125 citation statements)

References 47 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: 56%

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: 56%

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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“…Following this scheme, we find that ULIRGs whose SLED increases with increasing J tend to have warm color indices, those with decreasing SLEDs (i.e., SLED peaking at  J 6) have cold color indices, and those displaying flat SLEDS have intermediate color indices. Thus, the shape of the SLED appears to be influenced by the physical properties (e.g., temperature) of the underlying radiation field, which was also noted by Lu et al (2014) for their sample of LIRG galaxies. Finally, we note that an AGN (i.e., warm ULIRGs) will shift the peak of the SLED to higher J transitions, which may be a contributor to both higher C(60/100) colors and warmer SLEDs.…”

Section: Co Sled Modelingmentioning

confidence: 57%

HERUS: A CO ATLAS FROM SPIRE SPECTROSCOPY OF LOCAL ULIRGs

Pearson¹,

Rigopoulou²,

Hurley³

et al. 2016

ApJS

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We present the Herschel SPIRE Fourier Transform Spectroscopy (FTS) atlas for a complete flux-limited sample of local ultraluminous infrared galaxies (ULIRGs) as part of the HERschel Ultra Luminous InfraRed Galaxy Survey (HERUS). The data reduction is described in detail and was optimized for faint FTS sources ,with particular care being taken for the subtraction of the background, which dominates the continuum shape of the spectra. To improve the final spectra, special treatment in the data reduction has been given to any observation suffering from artifacts in the data caused by anomalous instrumental effects. Complete spectra are shown covering 200-671 μm, with photometry in the SPIRE bands at 250, 350, and 500 μm. The spectra include near complete CO ladders for over half of our sample, as well as fine structure lines from [C I] 370 μm, [C I] 609 μm, and [N II] 205 μm. We also detect H 2 O lines in several objects. We construct CO spectral line energy distributions (SLEDs) for the sample, and compare their slopes with the far-infrared (FIR) colors and luminosities. We show that the CO SLEDs of ULIRGs can be broadly grouped into three classes based on their excitation. We find that the mid-J (5<J<8) lines are better correlated with the total FIR luminosity, suggesting that the warm gas component is closely linked to recent star formation. The higher J transitions do not linearly correlate with the FIR luminosity, consistent with them originating in hotter, denser gas that is unconnected to the current star formation. We conclude that in most cases more than one temperature component is required to model the CO SLEDs.

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“…GOALS 14 is a multi-wavelength survey aimed at understanding the physical conditions and activity in the most luminous galaxies in the local universe. The data set includes spectroscopic and imaging observations in the infrared from Spitzer (Petric et al 2011;Inami et al 2013;Stierwalt et al 2013, J. M. Mazzarella et al 2015, in preparation), and Herschel (DiazSantos et al 2013, 2014Lu et al 2014), GALEX, and Hubble Space Telescope (HST) UV, optical, and near-infrared imaging (Howell et al 2010;Haan et al 2011;Kim et al 2013, A. S. Evans et al 2015, Chandra X-ray observations (Iwasawa et al 2011), and a suite of ground-based radio and sub-millimeter observations (e.g., Leroy et al 2011;BarcosMuñoz et al 2015, R. Herrero-Illana et al 2015. These observations collectively trace the obscured and unobscured activity and constrain the structural properties and merger stages of these systems.…”

Section: Goalsmentioning

confidence: 99%

EXCITATION MECHANISMS FOR HCN(1–0) AND HCO⁺(1–0) IN GALAXIES FROM THE GREAT OBSERVATORIES ALL-SKY LIRG SURVEY*

Privon

Herrero-Illana

Evans

et al. 2015

ApJ

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For L IR - The best-fit lines in Figure 6 of the original article are correct and the conclusions of the paper are not affected. We thank Iván Oteo for bringing the discrepancy in the original paper to our attention. , and J HNC 1 0 ( ) =  , for a sample of 58 local luminous and ultraluminous infrared galaxies from the Great Observatories All-sky LIRG Survey (GOALS). By combining our new IRAM data with literature data and Spitzer/IRS spectroscopy, we study the correspondence between these putative tracers of dense gas and the relative contribution of active galactic nuclei (AGNs) and star formation to the mid-infrared luminosity of each system. We find the HCN (1-0) emission to be enhanced in AGN-dominated systems (áL HCN 1 0 ¢ + emission do not appear to have a simple interpretation in terms of the AGN dominance or the star formation rate, and are likely determined by multiple processes, including density and radiative effects.

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Warm Molecular Gas in Luminous Infrared Galaxies

Cited by 59 publications

References 47 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

HERUS: A CO ATLAS FROM SPIRE SPECTROSCOPY OF LOCAL ULIRGs

EXCITATION MECHANISMS FOR HCN(1–0) AND HCO⁺(1–0) IN GALAXIES FROM THE GREAT OBSERVATORIES ALL-SKY LIRG SURVEY*

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Warm Molecular Gas in Luminous Infrared Galaxies

Cited by 59 publications

References 47 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

HERUS: A CO ATLAS FROM SPIRE SPECTROSCOPY OF LOCAL ULIRGs

EXCITATION MECHANISMS FOR HCN(1–0) AND HCO+(1–0) IN GALAXIES FROM THE GREAT OBSERVATORIES ALL-SKY LIRG SURVEY*

Contact Info

Product

Resources

About

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

EXCITATION MECHANISMS FOR HCN(1–0) AND HCO⁺(1–0) IN GALAXIES FROM THE GREAT OBSERVATORIES ALL-SKY LIRG SURVEY*