Detection of a large fraction of atomic gas not associated with star-forming material in M17 SW

Pérez-Beaupuits, J. P.; Stützki, J.; Ossenkopf, V.; Spaans, Marco; Güsten, R.; Wiesemeyer, H.

doi:10.1051/0004-6361/201425020

Cited by 28 publications

(39 citation statements)

References 86 publications

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“…from the cold component is about 80% larger than the mass of 1.45 × 10 4 M obtained by Stutzki & Güsten (1990) using C[C II] observations (Pérez-Beaupuits et al 2015). The size of a cloudlet obtained from the average spectra is not scaled up in the 200 region.…”

Section: Notesmentioning

confidence: 61%

“…The IRAM 30 m observations toward M17 SW were described in Pérez-Beaupuits et al (2015). Here we use the J = 1 → 0 and J = 2 → 1 maps of 12 CO and 13 CO reported there.…”

Section: The Iram 30 M Datamentioning

confidence: 99%

“…More recent results from the Stratospheric Observatory for Infrared Astronomy (SOFIA) and the German REceiver for Astronomy at Terahertz frequencies (GREAT) showed that the line profiles and distribution of the [C II] 158 μm emission support the clumpy scenario in M17 SW (Pérez-Beaupuits et al 2012) and that at least 64% of the [C II] 158 μm emission is not associated with the star-forming material traced by the [C I] and C 18 O lines (Pérez-Beaupuits et al 2013, 2015.…”

Section: Introductionmentioning

confidence: 99%

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Disentangling the excitation conditions of the dense gas in M17 SW

Pérez-Beaupuits

Güsten

Spaans

et al. 2015

A&A

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Context. Stars are formed in dense molecular clouds. These dense clouds experience radiative feedback from UV photons, and X-ray from stars, embedded prestellar cores, young stellar objects (YSOs), and ultra compact H II regions. This radiative feedback affects the chemistry and thermodynamics of the gas. Aims. We aim to probe the chemical and energetic conditions created by radiative feedback through observations of multiple CO, HCN, and HCO + transitions. We measure the spatial distribution and excitation of the dense gas (n(H 2 ) > 10 4 cm −3 ) in the core region of M17 SW and aim to investigate the influence of UV radiation fields. Methods. We used the dual band receiver GREAT on board the SOFIA airborne telescope to obtain a 5. 7 × 3. 7 map of the J = 16 → 15, J = 12 → 11, and J = 11 → 10 transitions of 12 CO in M17 SW. We compare these maps with corresponding APEX and IRAM 30 m telescope data for low-and mid-J CO, HCN, and HCO + emission lines, including maps of the HCN J = 8 → 7 and HCO + J = 9 → 8 transitions. The excitation conditions of 12 CO, HCO + , and HCN are estimated with a two-phase non-LTE radiative transfer model of the line spectral energy distributions (LSEDs) at four selected positions. The energy balance at these positions is also studied. Results. We obtained extensive LSEDs for the CO, HCN, and HCO + molecules toward M17 SW. These LSEDs can be fit simultaneously using the same density and temperature in the two-phase models and to the spectra of all three molecules over a ∼12 square arc minute size region of M17 SW. Temperatures of up to 240 K are found toward the position of the peak emission of the 12 CO J = 16 → 15 line. High densities of 10 6 cm −3 were found at the position of the peak HCN J = 8 → 7 emission. Conclusions. We found HCO + /HCN line ratios larger than unity, which can be explained by a lower excitation temperature of the higher-J HCN lines. The LSED shape, particularly the high-J tail of the CO lines observed with SOFIA/GREAT, is distinctive for the underlying excitation conditions. The cloudlets associated with the cold component of the models are magnetically subcritical and supervirial at most of the selected positions. The warm cloudlets instead are all supercritical and also supervirial. The critical magnetic field criterion implies that the cold cloudlets at two positions are partially controlled by processes that create and dissipate internal motions. Supersonic but sub-Alfvénic velocities in the cold component at most selected positions indicate that internal motions are likely magnetohydrodynamic (MHD) waves. Magnetic pressure dominates thermal pressure in both gas components at all selected positions, assuming random orientation of the magnetic field. The magnetic pressure of a constant magnetic field throughout all the gas phases can support the total internal pressure of the cold components, but cannot support the internal pressure of the warm components. If the magnetic field scales as B ∝ n 2/3 , then the evolution of the cold cloudlets at two sel...

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Section: Notesmentioning

confidence: 61%

“…The IRAM 30 m observations toward M17 SW were described in Pérez-Beaupuits et al (2015). Here we use the J = 1 → 0 and J = 2 → 1 maps of 12 CO and 13 CO reported there.…”

Section: The Iram 30 M Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Disentangling the excitation conditions of the dense gas in M17 SW

Pérez-Beaupuits

Güsten

Spaans

et al. 2015

A&A

Self Cite

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“…For instance, in our own Galaxy 80 per cent of the [CII] comes from atomic and molecular regions and 20 per cent from ionised gas (Pineda, Langer & Goldsmith 2014). For M17SW in the Milky Way the fraction of [CII] from ionised regions is as high as 33% (Pérez-Beaupuits et al 2015).…”

Section: [Cii] Emission From Ionised Regionsmentioning

confidence: 88%

Sub-mm emission line deep fields: CO and [C ii] luminosity functions out toz= 6

Popping

Kampen

Decarli

et al. 2016

Mon. Not. R. Astron. Soc.

114

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Now that ALMA is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J=1-0 out to CO J=6-5 and [CII] at redshifts z=0-6. We find that: 1) our model correctly reproduces the CO and [CII] emission of low-and high-redshift galaxies and reproduces the available constraints on the CO luminosity function at z 2.75; 2) we find that the CO and [CII] luminosity functions of galaxies increase from z = 6 to z = 4, remain relatively constant till z = 1 and rapidly decrease towards z = 0. The galaxies that are brightest in CO and [CII] are found at z ∼ 2; 3) the CO J=3-2 emission line is most favourable to study the CO luminosity and global H 2 mass content of galaxies, because of its brightness and observability with currently available sub-mm and radio instruments; 4) the luminosity functions of high-J CO lines show stronger evolution than the luminosity functions of low-J CO lines; 5) our model barely reproduces the available constraints on the CO and [CII] luminosity function of galaxies at z 1.5 and the CO luminosity of individual galaxies at intermediate redshifts. We argue that this is driven by a lack of cold gas in galaxies at intermediate redshifts as predicted by cosmological simulations of galaxy formation.

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“…This yields σ cl = 2 km s −1 . Other published mass estimates range from a few times 10 3 to 6 × 10 4 M (Pérez- Beaupuits et al 2015;Povich et al 2009), corresponding to σ cl = 1.4 to 5.2 km s −1 . Adopting the former value has no impact on our results while picking the latter one would only strengthen our conclusions because it leaves almost no room for binary contributions to the observed σ 1D value.…”

Section: Methodsmentioning

confidence: 99%

A dearth of short-period massive binaries in the young massive star forming region M 17

Sana

Ramírez-Tannus

Koter

et al. 2017

A&A

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Aims. The formation of massive stars remains poorly understood and little is known about their birth multiplicity properties. Here, we aim to quantitatively investigate the strikingly low radial-velocity dispersion measured for a sample of 11 massive pre-and nearmain-sequence stars (σ 1D = 5.6 ± 0.2 km s −1 ) in the very young massive star forming region M 17, in order to obtain first constraints on the multiplicity properties of young massive stellar objects. Methods. We compute the radial-velocity dispersion of synthetic populations of massive stars for various multiplicity properties and we compare the obtained σ 1D distributions to the observed value. We specifically investigate two scenarios: a low binary fraction and a dearth of short-period binary systems. Results. Simulated populations with low binary fractions ( f bin = 0.12 +0.16 −0.09 ) or with truncated period distributions (P cutoff > 9 months) are able to reproduce the low σ 1D observed within their 68%-confidence intervals. Furthermore, parent populations with f bin > 0.42 or P cutoff < 47 d can be rejected at the 5%-significance level. Both constraints are in stark contrast with the high binary fraction and plethora of short-period systems in few Myr-old, well characterized OB-type populations. To explain the difference in the context of the first scenario would require a variation of the outcome of the massive star formation process. In the context of the second scenario, compact binaries must form later on, and the cut-off period may be related to physical length-scales representative of the bloated pre-main-sequence stellar radii or of their accretion disks. Conclusions. If the obtained constraints for the M 17's massive-star population are representative of the multiplicity properties of massive young stellar objects, our results may provide support to a massive star formation process in which binaries are initially formed at larger separations, then harden or migrate to produce the typical (untruncated) power-law period distribution observed in few Myr-old OB binaries.

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Detection of a large fraction of atomic gas not associated with star-forming material in M17 SW

Cited by 28 publications

References 86 publications

Disentangling the excitation conditions of the dense gas in M17 SW

Disentangling the excitation conditions of the dense gas in M17 SW

Sub-mm emission line deep fields: CO and [C ii] luminosity functions out toz= 6

A dearth of short-period massive binaries in the young massive star forming region M 17

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