Evidence of a pure starburst nature of the nuclear  
region of NGC 253

Brunthaler, A.; Castangia, P.; Tarchi, A.; Henkel, C.; Reid, M. J.; Falcke, H.; Menten, K. M.

doi:10.1051/0004-6361/200911615

Cited by 34 publications

(52 citation statements)

References 44 publications

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“…Some of these clumps have been seen in previous interferometric studies of Turner & Ho (1985) are called THn, among which TH2 is thought to be at the galactic center (or within 2 of it; Fernández-Ontiveros et al 2009). The nuclear region has two water masers H 2 O_1 (at V LSR ≈ 120 km s −1 ) and H 2 O_2 (170 km s −1 ) associated with star formation (Henkel et al 2004;Hofner et al 2006;Brunthaler et al 2009). H 2 O_2 is likely associated with the molecular cloud complex that has the peak line velocity of 170 km s −1 (see Figure 6) and includes the continuum peak No.…”

Section: Overview Of the Central Molecular Zonementioning

confidence: 99%

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Sakamoto

Mao

Matsushita

et al. 2011

ApJ

123

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We report 350 and 230 GHz observations of molecular gas and dust in the starburst nucleus of NGC 253 at 20-40 pc (1 -2 ) resolution. The data contain CO(3-2), HCN(4-3), CO(2-1), 13 CO(2-1), C 18 O(2-1), and continuum at 0.87 mm and 1.3 mm toward the central kiloparsec. The CO(2-1) size of the galaxy's central molecular zone (CMZ) is measured to be about 300 pc × 100 pc at the half-maximum of intensity. Five clumps of dense and warm gas stand out in the CMZ at arcsecond resolution, and they are associated with compact radio sources due to recent massive star formation. They contribute one-third of the CO emission in the central 300 pc and have 12 CO peak brightness temperatures around 50 K, molecular gas column densities on the order of 10 4 M pc −2 , gas masses on the order of 10 7 M in the size scale of 20 pc, volume-averaged gas densities of n H 2 ∼ 4000 cm −3 , and high HCN-to-CO ratios suggestive of higher fractions of dense gas than in the surrounding environment. It is suggested that these are natal molecular cloud complexes of massive star formation. The CMZ of NGC 253 is also compared with that of our Galaxy in CO(2-1) at the same 20 pc resolution. Their overall gas distributions are strikingly similar. The five molecular cloud complexes appear to be akin to such molecular complexes as Sgr A, Sgr B2, Sgr C, and the l = 1.• 3 cloud in the Galactic center. On the other hand, the starburst CMZ in NGC 253 has higher temperatures and higher surface (and presumably volume) densities than its non-starburst cousin.

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Section: Overview Of the Central Molecular Zonementioning

confidence: 99%

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Sakamoto

Mao

Matsushita

et al. 2011

ApJ

123

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“…NGC 253 hosts a nuclear starburst. Radio continuum measurements indicate that NGC 253 contains a large number of potential centrally located supernova remnants and H ii regions (Ulvestad & Antonucci 1997;Brunthaler et al 2009). …”

Section: Ngc 253mentioning

confidence: 99%

Dense gas in nearby galaxies

Lebrón

Mangum

Mauersberger

et al. 2011

A&A

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Context. The central few 100 pc of galaxies often contain large amounts of molecular gas. The chemical and physical properties of these extragalactic star formation regions differ from those in galactic disks, but are poorly constrained. Aims. This study aims to develop a better knowledge of the spatial distribution and kinetic temperature of the dense neutral gas associated with the nuclear regions of three prototypical spiral galaxies, NGC 253, IC 342, and Maffei 2. Methods. VLA CnD and D configuration measurements have been made of three ammonia (NH 3 ) inversion transitions. Results. The (J, K) = (1, 1) and (2, 2) transitions of NH 3 were imaged toward IC 342 and Maffei 2. The (3, 3) transition was imaged toward NGC 253. The entire flux obtained from single-antenna measurements is recovered for all three galaxies observed. Derived lower limits to the kinetic temperatures determined for the giant molecular clouds in the centers of these galaxies are between 25 and 50 K. There is good agreement between the distributions of NH 3 and other H 2 tracers, such as rare CO isotopologues or HCN, suggesting that NH 3 is representative of the distribution of dense gas. The "Western Peak" in IC 342 is seen in the (6, 6) line but not in lower transitions, suggesting maser emission in the (6, 6) transition.

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“…When excluding an association with the galactic nucleus, as discussed before, this discrepancy can be explained by invoking gas motions in clouds (see, e.g. Surcis et al 2009, for NGC 3256) or assuming that the masing gas belongs to a counter-rotating structure, an expanding supernova shell, or a starburst wind or outflow (see also Brunthaler et al 2009, for a detailed analysis with respect to NGC 253). With the data presently available for NGC 3556, it is impossible to distinguish between these possibilities.…”

Section: Ngc 3556mentioning

confidence: 99%

“…Indeed, as qualitatively suggested by Zhang et al (2006), the kilomasers associated, or most likely associated, with AGN activity are found in galaxies with higher nuclear column densities (10 23 cm −2 < N H < 10 25 cm −2 ), different from those with a star-forming origin, which are found in galaxies with nuclear column densities <10 23 cm −2 . The only exception is represented by the maser in NGC 253 that, despite being quite confidently associated with star formation (Hofner et al 2006;Brunthaler et al 2009), Histogram showing the number of H 2 O kilomaser galaxies as a function of their nuclear column density derived from X-ray spectroscopy. Due to the higher angular resolution, Chandra data are taken whenever possible (with the exception of NGC 4051 for which the XMM-derived column density value was preferred to that of Chandra because of the large uncertainties reported).…”

Section: Kilomasers Revisitedmentioning

confidence: 99%

New H₂O masers in Seyfert and FIR bright galaxies

Tarchi

Castangia

Henkel

et al. 2010

A&A

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Context. Very luminous extragalactic water masers, the megamasers, are associated with active galactic nuclei (AGN) in galaxies characterized by accretion disks, radio jets, and nuclear outflows. Weaker masers, the kilomasers, seem to be related mostly to star formation activity, although the possibility exists that some of these sources may belong to the weak tail of the AGN maser distribution. Aims. It is particularly important to accurately locate the water maser emission to reveal its origin and shed light on extragalactic starforming activity or to elucidate the highly obscured central regions of galaxies. Methods. We performed interferometric observations of three galaxies, NGC 3556, Arp 299, and NGC 4151, where water emission was found. Statistical tools were used to study the relation between OH and H 2 O maser emission in galaxies. Results. The maser in NGC 3556 is associated with a compact radio continuum source that is most likely a supernova remnant or radio supernova. In Arp 299, the luminous water maser has been decomposed in three main emitting regions associated with the nuclear regions of the two main galaxies of the system, NGC 3690 and IC 694, and the region of overlap. In NGC 4151, only one of the two previously observed maser components has been tentatively detected. This feature, if real, is associated with the galaxy's central region. The only galaxy, so far, where luminous maser emission from two maser species, OH and H 2 O, has been confidently detected is Arp 299. Weaker masers from these two species instead coexist in a number of objects. A search for emission from both maser species in a larger number of galaxies is, however, needed to assess these last two results better.

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Evidence of a pure starburst nature of the nuclear region of NGC 253

Cited by 34 publications

References 44 publications

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Dense gas in nearby galaxies

New H₂O masers in Seyfert and FIR bright galaxies

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Evidence of a pure starburst nature of the nuclear region of NGC 253

Cited by 34 publications

References 44 publications

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Star-Forming Cloud Complexes in the Central Molecular Zone of NGC 253

Dense gas in nearby galaxies

New H2O masers in Seyfert and FIR bright galaxies

Contact Info

Product

Resources

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New H₂O masers in Seyfert and FIR bright galaxies