A 2 Millimeter Spectral Line Survey of the Starburst Galaxy NGC 253

Martín, S.; Mauersberger, R.; Martı́n-Pintado, J.; Henkel, C.; García‐Burillo, S.

doi:10.1086/503297

Cited by 222 publications

(379 citation statements)

References 91 publications

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“…With these (Martín et al 2006) and the reported detections of: HD and LiH in absorption at high redshift (Combes & Wiklind 1998;Varshalovich et al 2001); H + 3 in absorption towards the ULIRG IRAS 08572+3915 (Geballe et al 2006 parameters we have estimated the contribution of the J = 14−13 group to the emission of the CH 3 CN spectral feature at 239 GHz. S O− Only the 5 4 −4 3 and 5 5 −4 4 transitions at 206.1 and 215.2 GHz are detected unambiguously and not affected by blending to other lines.…”

Section: Details On the Fitting Of Individual Speciesmentioning

confidence: 89%

“…Such scatter in the chemical composition are found both in prototypical nearby galaxies and Galactic sources as described in Sects. 4.4.1 and 4.4.2 in Martín et al (2006), respectively…”

Section: Chemical Composition Of Arp 220mentioning

confidence: 92%

“…Although their sample does not include ULIRGs, where line contribution appears to be very important, the emission of molecules other than CO might be also important in some of their sources. In particular, the line contamination to the continuum flux density might become significant in starbursts, where an also prolific molecular emission is observed (Martín et al 2006). Our observations show that at short mm and sub-mm wavelengths, the flux density correction due to molecular line emission is more important than the non-thermal contribution extrapolated from radio measurements (Norris 1988;Scoville et al 1997).…”

Section: Line Contribution To Total Emission Flux In Broad Band Obsermentioning

confidence: 99%

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The Submillimeter Array 1.3 mm line survey of Arp 220

Martín

Krips

Martı́n-Pintado

et al. 2011

A&A

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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Section: Details On the Fitting Of Individual Speciesmentioning

confidence: 89%

“…Such scatter in the chemical composition are found both in prototypical nearby galaxies and Galactic sources as described in Sects. 4.4.1 and 4.4.2 in Martín et al (2006), respectively…”

Section: Chemical Composition Of Arp 220mentioning

confidence: 92%

Section: Line Contribution To Total Emission Flux In Broad Band Obsermentioning

confidence: 99%

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The Submillimeter Array 1.3 mm line survey of Arp 220

Martín

Krips

Martı́n-Pintado

et al. 2011

A&A

159

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“…The large overall abundance of HCO in M 82 has been interpreted as evidence for a chemistry mainly dominated by photon-dominated regions (PDRs) within its central ∼ 650 pc (García-Burillo et al 2002), which does not mean that other processes like shocks or X-ray heating do not take place in its nucleus . The dissociating radiation explains the low abundance in M 82 of the complex and fragile species cited above (Mauersberger et al 2003;Martín et al 2006a). Other molecules like CS are not under-abundant in M 82 relative to NGC 253, which can also be explained in terms of PDRs chemistry, since a high abundance of this molecule is predicted for slightly shielded regions (Drdla et al 1989;Sternberg & Dalgarno 1995).…”

Section: Introductionmentioning

confidence: 99%

CS, HC₃N, and CH₃CCH multi-line analyses toward starburst galaxies

Aladro

Martı́n-Pintado

Martín

et al. 2010

A&A

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Aims. We aim to study the properties of the dense molecular gas towards the inner few 100 pc of four nearby starburst galaxies dominated both by photo dissociation regions (M 82) and large-scale shocks (NGC 253, IC 342 and Maffei 2), and to relate the chemical and physical properties of the molecular clouds with the evolutionary stage of the nuclear starbursts. Methods. We have carried out multi-transitional observations and analyses of three dense gas molecular tracers, CS, HC 3 N (cyanoacetylene) and CH 3 CCH (methyl acetylene), using Boltzmann diagrams in order to determine the rotational temperatures and column densities of the dense gas, and using a Large Velocity Gradients model to calculate the H 2 density structure in the molecular clouds.Results. The CS and HC 3 N data indicate the presence of density gradients in the molecular clouds. These two molecules show similar excitation conditions, suggesting that they arise from the same gas components. In M 82, CH 3 CCH has the highest fractional abundance determined in a extragalactic source (1.1 × 10 −8 ). Conclusions. The density and the chemical gradients we have found in all galaxies can be explained in the framework of the starburst evolution, which affects the chemistry and the structure of molecular clouds around the galactic nuclei. The young shock-dominated starburst galaxies, like presumably Maffei 2, show a cloud structure with a rather uniform density and chemical composition which suggests low star formation activity. Molecular clouds in galaxies with starburst in an intermediate stage of evolution, such as NGC 253 and IC 342, show clouds with a large density contrast (two orders of magnitude) between the denser regions (cores) and the less dense regions (halos) of the molecular clouds and relatively constant chemical abundance. Finally, the galaxy with the most evolved starburst, M 82, has clouds with a rather uniform density structure, large envelopes of atomic/molecular gas subjected to UV photodissociating radiation from young star clusters, and very different chemical abundances of HC 3 N and CH 3 CCH.

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“…A&A 550, A12 (2013) The subject of excitation mechanisms has been extensively studied in NGC 253. Martín et al (2006) finds that the chemistry and heating of NGC 253 is dominated by large scale, low velocity shocks. Presence of shocked molecular material is indeed evident through the presence of widespread SiO emission throughout the nuclear regions (García-Burillo et al 2000).…”

Section: Introductionmentioning

confidence: 99%

The excitation of near-infrared H₂emission in NGC 253

Rosenberg

Werf

Israel

2013

A&A

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Context. Because of its large angular size and proximity to the Milky Way, NGC 253, an archetypal starburst galaxy, provides an excellent laboratory to study the intricacies of this intense episode of star formation. Aims. We aim to characterize the excitation mechanisms driving the emission in NGC 253. Specifically we aim to distinguish between shock excitation and ultraviolet (UV) excitation as the dominant driving mechanism, using Brγ, H 2 and [FeII] as diagnostic emission line tracers. Methods. Using SINFONI observations, we create linemaps of Brγ, [FeII] 1.64 , and all detected H 2 transitions. By using symmetry arguments of the gas and stellar gas velocity field, we find a kinematic center in agreement with previous determinations. The ratio of the 2-1 S(1) to 1-0 S(1) H 2 transitions can be used as a diagnostic to discriminate between shock and fluorescent excitation. Results. Using the 1-0 S(1)/2-1 S(1) line ratio as well as several other H 2 line ratios and the morphological comparison between H 2 and Brγ and [FeII], we find that excitation from UV photons is the dominant excitation mechanisms throughout NGC 253. We employ a diagnostic energy level diagram to quantitatively differentiate between mechanisms. We compare the observed energy level diagrams to photon-dominated region (PDR) and shock models and find that in most regions and over the galaxy as a whole, fluorescent excitation is the dominant mechanism exciting the H 2 gas. We also place an upper limit of the percentage of shock excited H 2 at 29%. Conclusions. We find that UV radiation is the dominant excitation mechanism for the H 2 emission. The H 2 emission does not correlate well with Brγ but closely traces the polycyclic aromatic hydrocarbon emission, showing that not only is H 2 fluorescently excited, but it is predominately excited by slightly lower mass stars than O stars which excite Brγ, such as B stars.

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A 2 Millimeter Spectral Line Survey of the Starburst Galaxy NGC 253

Cited by 222 publications

References 91 publications

The Submillimeter Array 1.3 mm line survey of Arp 220

The Submillimeter Array 1.3 mm line survey of Arp 220

CS, HC₃N, and CH₃CCH multi-line analyses toward starburst galaxies

The excitation of near-infrared H₂emission in NGC 253

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A 2 Millimeter Spectral Line Survey of the Starburst Galaxy NGC 253

Cited by 222 publications

References 91 publications

The Submillimeter Array 1.3 mm line survey of Arp 220

The Submillimeter Array 1.3 mm line survey of Arp 220

CS, HC3N, and CH3CCH multi-line analyses toward starburst galaxies

The excitation of near-infrared H2emission in NGC 253

Contact Info

Product

Resources

About

CS, HC₃N, and CH₃CCH multi-line analyses toward starburst galaxies

The excitation of near-infrared H₂emission in NGC 253