Luminous HC<sub>3</sub>N line and the HCN/HCO<sup>+</sup> ratio in NGC 4418

Aalto, S.; Monje, Raquel; Martín, S.

doi:10.1051/0004-6361:20077366

Cited by 56 publications

(89 citation statements)

References 21 publications

(41 reference statements)

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“…The inferred redshift is fully consistent with observations of CO, CN, HNC, and other molecular species observed at millimeter wavelengths (e.g. Aalto et al 2007a). The Sloan Digital Sky Survey (SDSS) spectrum of NGC 4418 also gives a consistent redshift for the optical absorption/emission lines of z = 0.0070 and 0.0072, respectively (D. Rupke, private communication).…”

Section: Systemic Redshiftssupporting

confidence: 88%

“…The current models underpredict the low-J lines of HCN observed by Aalto et al (2007a) in NGC 4418, who derived densities of ∼10 5 cm −3 ; we derive much higher densities, ∼3 × 10 6 cm −3 , for the high-J lines. Likewise, our models for the high-J lines in Arp 220 underpredict the J = 6 → 5 measurement of Rangwala et al (2011).…”

Section: Model Uncertaintiescontrasting

confidence: 48%

“…by Lahuis et al (2007) from the HCN 14 μm absorption in these and other (U)LIRGs, Martín et al (2011) for Arp 220 based on multispecies observations at 1.3 mm, and Aalto et al (2007a) and Costagliola & Aalto (2010) to explain the luminous HC 3 N emission in NGC 4418. HCN is well known to be enhanced in Galactic hot cores, as in the Orion hot core where the abundance is ∼10 −6 (Schilke et al 1992), about two orders of magnitude higher than in cold molecular clouds.…”

Section: Model Uncertaintiesmentioning

confidence: 97%

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Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃

González-Alfonso

Fischer

Graciá-Carpio

et al. 2012

A&A

156

166

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Full range Herschel/PACS spectroscopy of the (ultra)luminous infrared galaxies NGC 4418 and Arp 220, observed as part of the SHINING key programme, reveals high excitation in H 2 O, OH, HCN, and NH 3 . In NGC 4418, absorption lines were detected with E lower > 800 K (H 2 O), 600 K (OH), 1075 K (HCN), and 600 K (NH 3 ), while in Arp 220 the excitation is somewhat lower. While outflow signatures in moderate excitation lines are seen in Arp 220 as have been seen in previous studies, in NGC 4418 the lines tracing its outer regions are redshifted relative to the nucleus, suggesting an inflow withṀ 12 M yr −1 . Both galaxies have compact and warm (T dust 100 K) nuclear continuum components, together with a more extended and colder component that is much more prominent and massive in Arp 220. A chemical dichotomy is found in both sources: on the one hand, the nuclear regions have high H 2 O abundances, ∼10 −5 , and high HCN/H 2 O and HCN/NH 3 column density ratios of 0.1−0.4 and 2−5, respectively, indicating a chemistry typical of evolved hot cores where grain mantle evaporation has occurred. On the other hand, the high OH abundance, with OH/H 2 O ratios of ∼0.5, indicates the effects of X-rays and/or cosmic rays. The nuclear media have high surface brightnesses ( 10 13 L /kpc 2 ) and are estimated to be very thick (N H 10 25 cm −2 ). While NGC 4418 shows weak absorption in H 18 2 O and 18 OH, with a 16 O-to-18 O ratio of 250−500, the relatively strong absorption of the rare isotopologues in Arp 220 indicates 18 O enhancement, with 16 O-to-18 O of 70−130. Further away from the nuclear regions, the H 2 O abundance decreases to 10 −7 and the OH/H 2 O ratio is reversed relative to the nuclear region to 2.5−10. Despite the different scales and morphologies of NGC 4418, Arp 220, and Mrk 231, preliminary evidence is found for an evolutionary sequence from infall, hot-core like chemistry, and solar oxygen isotope ratio to high velocity outflow, disruption of the hot core chemistry and cumulative high mass stellar processing of 18 O.

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Section: Systemic Redshiftssupporting

confidence: 88%

Section: Model Uncertaintiescontrasting

confidence: 48%

Section: Model Uncertaintiesmentioning

confidence: 97%

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Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃

González-Alfonso

Fischer

Graciá-Carpio

et al. 2012

A&A

156

166

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“…HC 3 N enhancement has been confirmed in other obscured LIRGs (Costagliola et al 2011). The observed HC 3 N/HCO + integrated intensity ratio toward NGC 4418 is ∼0.4-0.6 (Aalto et al 2007;Costagliola et al 2011). This is using the J = 10−9 transition of HC 3 N, and therefore the ratio would be higher if using the J = 11−10 in our work.…”

Section: The Cnd Traced By Hncomentioning

confidence: 79%

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

Martín

Kohno

Izumi

et al. 2015

A&A

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Context. The nearby Sy 1 galaxy NGC 1097 represents an ideal laboratory for exploring the molecular chemistry in the surroundings of an active galactic nucleus (AGN). Aims. Exploring the distribution of different molecular species allows us to understand the physical processes affecting the interstellar medium both in the AGN vicinity and in the outer star forming molecular ring. Methods. We carried out 3 mm ALMA observations that include seven different molecular species, namely HCN, HCO + , CCH, CS, HNCO, SiO, HC 3 N, and SO, as well as the 13 C isotopologues of the first two. Spectra were extracted from selected positions and all species were imaged over the central 2 kpc (∼30 ) of the galaxy at a resolution of ∼2.2 × 1.5 (150 pc × 100 pc). Results. HCO + and CS appear to be slightly enhanced in the star forming ring. CCH shows the largest variations across NGC 1097 and is suggested to be a good tracer of both obscured and early stage star formation. HNCO, SiO, and HC 3 N are significantly enhanced in the inner circumnuclear disk surrounding the AGN. Conclusions. Differences in the molecular abundances are observed between the star forming ring and the inner circumnuclear disk. We conclude that the HCN/HCO + and HCN/CS differences observed between AGN-dominated and starburst (SB) galaxies are not due to a HCN enhancement due to X-rays, but rather this enhancement is produced by shocked material at distances of 200 pc from the AGN. Additionally, we claim that lower HCN/CS is a combination of a small underabundance of CS in AGNs, together with excitation effects, where a high density gas component (∼10 6 cm −3 ) may be more prominent in SB galaxies. However, the most promising are the differences found among the dense gas tracers that, at our modest spatial resolution, seem to outline the physical structure of the molecular disk around the AGN. In this picture, HNCO probes the well-shielded gas in the disk, surrounding the dense material moderately exposed to the X-ray radiation traced by HC 3 N. Finally SiO might be the innermost molecule in the disk structure.

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“…The results from such models (Meijerink & Spaans 2005;Meijerink et al 2006Meijerink et al , 2007Loenen et al 2008) have motivated a number of observational studies focused on the species CO, HCN, HNC, HCO + , and CN (Pérez-Beaupuits et al 2007;Krips et al 2008;Baan et al 2008;Pérez-Beaupuits et al 2009). The HCN/HCO + ratio was used by (Aalto et al 2007a) to evaluate the presence of an AGN on the LIRG NGC 4418 which, like Arp 220, has a heavily obscured nucleus. The HCN and HCO + comparative study by Krips et al (2008) shows how the HCN/HCO + ratios in Arp 220 are similar to those measured in NGC 1068, the prototypical AGN galaxy.…”

Section: Conclusion: Agn Vs Sb Driven Chemistrymentioning

confidence: 99%

The Submillimeter Array 1.3 mm line survey of Arp 220

Martín

Krips

Martı́n-Pintado

et al. 2011

A&A

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159

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Context. Though Arp 220 is the closest and by far the most studied ULIRG, a discussion is still ongoing on the main power source driving its huge infrared luminosity. Aims. To study the molecular composition of Arp 220 in order to find chemical fingerprints associated with the main heating mechanisms within its nuclear region. Methods. We present the first aperture synthesis unbiased spectral line survey toward an extragalactic object. The survey covered the 40 GHz frequency range between 202 and 242 GHz of the 1.3 mm atmospheric window. Results. We find that 80% of the observed band shows molecular emission, with 73 features identified from 15 molecular species and 6 isotopologues. The 13 C isotopic substitutions of HC 3 N and transitions from H 18 2 O, 29 SiO, and CH 2 CO are detected for the first time outside the Galaxy. No hydrogen recombination lines have been detected in the 40 GHz window covered. The emission feature at the transition frequency of H31α line is identified to be an HC 3 N molecular line, challenging the previous detections reported at this frequency. Within the broad observed band, we estimate that 28% of the total measured flux is due to the molecular line contribution, with CO only contributing 9% to the overall flux. We present maps of the CO emission at a resolution of 2.9 × 1.9 which, though not enough to resolve the two nuclei, recover all the single-dish flux. The 40 GHz spectral scan has been modelled assuming LTE conditions and abundances are derived for all identified species. Conclusions. The chemical composition of Arp 220 shows no clear evidence of an AGN impact on the molecular emission but seems indicative of a purely starburst-heated ISM. The overabundance of H 2 S and the low isotopic ratios observed suggest a chemically enriched environment by consecutive bursts of star formation, with an ongoing burst at an early evolutionary stage. The large abundance of water (∼10 −5 ), derived from the isotopologue H 18 2 O, as well as the vibrationally excited emission from HC 3 N and CH 3 CN are claimed to be evidence of massive star forming regions within Arp 220. Moreover, the observations put strong constraints on the compactness of the starburst event in Arp 220. We estimate that such emission would require ∼2−8 × 10 6 hot cores, similar to those found in the Sgr B2 region in the Galactic center, concentrated within the central 700 pc of Arp 220.

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Luminous HC₃N line and the HCN/HCO⁺ ratio in NGC 4418

Cited by 56 publications

References 21 publications

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

The Submillimeter Array 1.3 mm line survey of Arp 220

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Luminous HC3N line and the HCN/HCO+ ratio in NGC 4418

Cited by 56 publications

References 21 publications

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH,18OH, O I, HCN, and NH3

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H2O, H218O, OH,18OH, O I, HCN, and NH3

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

The Submillimeter Array 1.3 mm line survey of Arp 220

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Product

Resources

About

Luminous HC₃N line and the HCN/HCO⁺ ratio in NGC 4418

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃

Herschel/PACS spectroscopy of NGC 4418 and Arp 220: H₂O, H₂¹⁸O, OH,¹⁸OH, O I, HCN, and NH₃