Molecular gas properties of 12-<i>μ</i>m Seyfert galaxies - I. The southern sample

Strong, M.; Pedlar, A.; Aalto, S.; Beswick, R.; Curran, S. J.; Booth, R. S.

doi:10.1111/j.1365-2966.2004.08139.x

Cited by 14 publications

(20 citation statements)

References 34 publications

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“…The value for I CO of the central position agrees within 18%. After correction for the different beam sizes, the 12 CO(1−0) detections of HE 0227-0913 with the NRO 45 m telescope by Vila-Vilaró et al (1998), of HE 1237-0504 with SEST by Curran et al (2000), and of HE 0433-1028 with SEST by Strong et al (2004) agree within 10% with the values presented in this paper. HE 1237-0504 was also observed by Maiolino et al (1997) with the NRAO 12 m telescope.…”

Section: Resultssupporting

confidence: 82%

“…So do several studies of the molecular gas content of Seyfert galaxies (e.g. Heckman et al 1989;Papadopoulos & Seaquist 1998;Strong et al 2004) or the study of PG QSO host galaxies by Evans et al (2001Evans et al ( , 2006. For the sample discussed in this paper an IR selection criterion was not introduced.…”

Section: Far Infrared Luminosity and Star Formation Efficiencymentioning

confidence: 99%

“…Sanders & Mirabel (1996). Figure 8 shows the distribution of the IRAS detected sources in the L CO − L FIR diagram, together with the CO data of a volume limited sample of nearby spiral galaxies (Sage 1993), Seyfert I galaxies (Heckman et al 1989;Maiolino et al 1997;Strong et al 2004), luminous (LIGs, Sanders et al 1991) and ultraluminous infrared galaxies (ULIGs, Solomon et al 1997), and PG QSOs (Scoville et al 2003;Evans et al 2006). Also shown are linear regression fits (in log-log space) to normal and to luminous IR galaxy samples as well as to the PG QSO hosts.…”

Section: Far Infrared Luminosity and Star Formation Efficiencymentioning

confidence: 99%

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Molecular gas in nearby low-luminosity QSO host galaxies

Bertram¹,

Eckart²,

Fischer³

et al. 2007

A&A

161

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Aims. This paper addresses the global molecular gas properties of a representative sample of galaxies hosting low-luminosity quasistellar objects. An abundant supply of gas is necessary to fuel both the active galactic nucleus and any circum-nuclear starburst activity of QSOs. The connection between ultraluminous infrared galaxies and the host properties of QSOs is still subject to a controversial debate. Nearby low-luminosity QSOs are ideally suited to study the properties of their host galaxies because of their higher frequency of occurrence compared to high-luminosity QSOs in the same comoving volume and because of their small cosmological distance. Methods. We selected a sample of nearby low-luminosity QSO host galaxies that is free of infrared excess biases. All objects are drawn from the Hamburg-ESO survey for bright UV-excess QSOs, have δ > −30• and redshifts that do not exceed z = 0.06. The IRAM 30 m telescope was used to measure the 12 CO(1−0) and 12 CO(2−1) transition in parallel. Results. 27 out of 39 galaxies in the sample have been detected. The molecular gas masses of the detected sources range from 0.4 × 10 9 M to 9.7 × 10 9 M . The upper limits of the non-detected sources correspond to molecular gas masses between 0.3 × 10 9 M and 1.2 × 10 9 M . We can confirm that the majority of galaxies hosting low-luminosity QSOs are rich in molecular gas. The properties of galaxies hosting brighter type I AGN and circumnuclear starformation regions differ from the properties of galaxies with fainter central regions. The overall supply of molecular gas and the spread of the line width distribution is larger. When comparing the farinfrared with the CO luminosities, the distribution can be separated into two different power-laws: one describing the lower activity Seyfert I population and the second describing the luminous QSO population. The separation in the L FIR /L CO behavior may be explainable with differing degrees of compactness of the emission regions. We provide a simple model to describe the two power-laws. The sample studied in this paper is located in a transition region between the two populations.

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Section: Resultssupporting

confidence: 82%

Section: Far Infrared Luminosity and Star Formation Efficiencymentioning

confidence: 99%

Section: Far Infrared Luminosity and Star Formation Efficiencymentioning

confidence: 99%

See 1 more Smart Citation

Molecular gas in nearby low-luminosity QSO host galaxies

Bertram¹,

Eckart²,

Fischer³

et al. 2007

A&A

161

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“…The largest remaining CO line flux discrepancy is for the LIRG IRAS 05189−2524 with S 10 = (91 ± 18) Jy km s −1 obtained for CO J = 1–0 with the National Radio Astronomy Observatory (NRAO) 12‐m telescope (Sanders et al ) and S 10 = (52 ± 10) Jy km s −1 with SEST (Strong et al ). The larger value would place this ULIRG to the lowest end of gas excitation of the entire sample, with r 32 = 0.24 and r 21 = 0.32, typical for the coldest, most quiescent GMCs found in the Galaxy and M 31 (Allen et al ; Loinard, Allen & Lequeux ; Fixsen, Bennett & Mather ).…”

Section: Data Reduction Line Intensity Estimates and Literature Datamentioning

confidence: 97%

The molecular gas in luminous infrared galaxies - I. CO lines, extreme physical conditions and their drivers

Papadopoulos

Werf

Xilouris

et al. 2012

Monthly Notices of the Royal Astronomical Society

213

254

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We report results from a large molecular line survey of luminous infrared galaxies (LIRGs; L IR 10 11 L ) in the local Universe (z ≤ 0.1), conducted during the last decade with the James Clerk Maxwell Telescope and the IRAM 30-m telescope. This work presents the CO and 13 CO line data for 36 galaxies, further augmented by multi-J total CO line luminosities available for other infrared (IR) bright galaxies from the literature. This yields a combined sample of N = 70 galaxies with the star formation (SF) powered fraction of their IR luminosities spanning L ( * ) IR ∼ (10 10 -2 × 10 12 ) L and a wide range of morphologies. Simple comparisons of their available CO spectral line energy distributions (SLEDs) with local ones, as well as radiative transfer models, discern a surprisingly wide range of average interstellar medium (ISM) conditions, with most of the surprises found in the high-excitation regime. These take the form of global CO SLEDs dominated by a very warm (T kin 100 K) and dense (n ≥ 10 4 cm −3 ) gas phase, involving galaxy-sized (∼(few) × 10 9 M ) gas mass reservoirs under conditions that are typically found only for ∼(1-3) per cent of mass per typical SF molecular cloud in the Galaxy. Furthermore, some of the highest excitation CO SLEDs are found in ultraluminous infrared galaxies (ULIRGs; L IR ≥ 10 12 L ) and surpass even those found solely in compact SF-powered hot spots in Galactic molecular clouds. Strong supersonic turbulence and high cosmic ray energy densities rather than far-ultraviolet/optical photons or supernova remnant induced shocks from individual SF sites can globally warm the large amounts of dense gas found in these merger-driven starbursts and easily power their extraordinary CO line excitation. This exciting possibility can now be systematically investigated with Herschel and the Atacama Large Milimeter Array (ALMA). As expected for an IR-selected (and thus SF rate selected) galaxy sample, only few 'cold' CO SLEDs are found, and for fewer still a cold low/moderate-density and gravitationally bound state (i.e. Galactic type) emerges as the most likely one. The rest remain compatible with a warm and gravitationally unbound low-density phase often found in ULIRGs. Such degeneracies, prominent when only the low-J SLED segment (J = 1-0, 2-1 and 3-2) is available, advise against using its CO line ratios and the so-called X co = M(H 2 )/L co (1-0) factor as SF mode indicators, a practice that may have led to the misclassification of the ISM environments of IR-selected gas-rich discs in the distant Universe. Finally, we expect that the wide range of ISM conditions found among LIRGs will strongly impact the X co factor, an issue we examine in detail in Paper II.

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“…Emission from hot dust, leaking out through a clumpy obscuring structure, might also explain the near-IR excess present in the nuclear SED of IRAS 15480 (Videla et al 2013). Molecular gas has been detected towards IRAS 15480 in the CO J = 2 → 1 transition, with centroid velocity 9039 km s −1 (Strong et al 2004). At radio frequencies, the nuclear emission is unresolved in the highest resolution radio maps available, so far, taken with the Very Large Array (VLA) at 8.4 GHz.…”

Section: The Compton-thick Seyfert Galaxy Iras 15480mentioning

confidence: 99%

Water masers in Compton-thick AGN

Castangia¹,

Tarchi²,

Caccianiga³

et al. 2016

A&A

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Context.A relationship between the water maser detection rate and large nuclear column densities in AGN has often been cited in the literature. Indeed, detailed studies of luminous water masers, typically associated with the nuclear activity, allow us to investigate the innermost regions of AGN, with an impact on the still debated Unified Model for this class of objects. Aims. We have recently entertained a search for maser emission in a well-defined sample of Compton-thick AGN aimed at investigating, on firm statistical bases, the aforementioned relationship. While the survey is still ongoing, and is the subject of a forthcoming publication, a new luminous water maser has been detected in the lenticular (field) S0 galaxy IRAS 15480-0344, whose origin, associated with an accretion disc or a nuclear outflow/jet, needs to be assessed. Methods. Multi-epoch single-dish observations and VLBI measurements were performed to investigate the distribution, spatial extension, and variability of the maser emission in order to infer the main characteristics of the water megamaser. Results. The new detection in IRAS 15480-0344 is reported: a megamaser with a total single-dish isotropic luminosity of ∼200 L and a profile composed of two main features, a broad line with a full width to half maximum (FWHM) linewidth of ∼90 km s −1 and a narrow (FWHM < 1 km s −1 ) one. We performed a follow-up to the detection with the Very Long Baseline Array (VLBA) and confidently detected only the narrow component, which is coincident with the nuclear radio continuum emission detected with the Very Large Array at 8.4 GHz. A weak narrow feature has also been detected in the velocity range of the broad feature and is located 15 pc to the north-west with respect to the stronger component. Neither maser spot is associated with the compact radio continuum sources derived from the same VLBA dataset. Conclusions. The different line profiles and the spatial separation between the two features in the spectrum of IRAS 15480-0344 suggests a composite origin for the maser. The large linewidth and the strong spectral variability indicate that the broad component might originate from the interaction between a radio jet and ambient molecular clouds. Based on its small linewidth and the absence of high velocity features, instead, we favour an outflow origin for the narrow component. This scenario is consistent with the hypothesis of the presence of strong nuclear outflows recently invoked to explain the main characteristics of field S0 galaxies.

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Molecular gas properties of 12-μm Seyfert galaxies - I. The southern sample

Cited by 14 publications

References 34 publications

Molecular gas in nearby low-luminosity QSO host galaxies

Molecular gas in nearby low-luminosity QSO host galaxies

The molecular gas in luminous infrared galaxies - I. CO lines, extreme physical conditions and their drivers

Water masers in Compton-thick AGN

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