Testing the Larson relations in massive clumps

Traficante, A.; Duarte-Cabral, A.; Elia, D.; Fuller, G. A.; Merello, Manuel; Molinari, S.; Peretto, N.; Schisano, E.; Giorgio, A. Di

doi:10.1093/mnras/sty798

Cited by 74 publications

(121 citation statements)

References 80 publications

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“…Similarly to the comparison between σ and Σ, the final sample shows a rather weak correlation (ρ = 0.32, p-value < 0.01), while the sub-sample of clumps described above presents a stronger correlation (ρ = 0.62, p-value < 0.01). A similar correlation has been found in a separated sample of Hi-GAL sources in different evolutionary stages associated with N2H + (1 − 0) emission (Traficante et al 2018a).…”

Section: Non-thermal Motions Driven By Gravitational Collapsesupporting

confidence: 85%

Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey

Merello

Molinari

Rygl

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present a comparative study of physical properties derived from gas and dust emission in a sample of 1068 dense Galactic clumps. The sources are selected from the crossmatch of the Hi-GAL survey with 16 catalogues of NH 3 line emission in its lowest inversion (1,1) and (2,2) transitions. The sample covers a large range in masses and bolometric luminosities, with surface densities above Σ = 0.1 g cm −2 and with low virial parameters α < 1. The comparison between dust and gas properties shows an overall agreement between T kin and T dust at volumetric densities n 1.2 × 10 4 cm −3 , and a median fractional abundance χ(NH 3 )= 1.46 × 10 −8 . While the protostellar clumps in the sample have small differences between T kin and T dust , prestellar clumps have a median ratio T kin /T dust = 1.24, suggesting that these sources are thermally decoupled. A correlation is found between the evolutionary tracer L/M and the parameters T kin /T dust and χ(NH 3 ) in prestellar sources and protostellar clumps with L/M < 1 L ⊙ M ⊙ −1 . In addition, a weak correlation is found between non-thermal velocity dispersion and the L/M parameter, possibly indicating an increase of turbulence with protostellar evolution in the interior of clumps. Finally, different processes are discussed to explain the differences between gas and dust temperatures in prestellar candidates, and the origin of non-thermal motions observed in the clumps.

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Section: Non-thermal Motions Driven By Gravitational Collapsesupporting

confidence: 85%

Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey

Merello

Molinari

Rygl

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…In the former scenario, we expect to observe a velocity dispersion-size relation, σ ∝ R δ , that resembles the turbulent cascade of energy when δ = 0.5 (Larson 1981;Heyer & Brunt 2004;McKee & Ostriker 2007;Federrath 2013). In Traficante et al (2018b) we have already discussed how this relation breaks down at the clump scales. We draw similar conclusions from our sample of objects, as shown in Figure 4, although our sample covers a limited range of radii.…”

Section: The Dynamics Of Star-forming Clumpsmentioning

confidence: 91%

“…We obtain surface densities Σ = M/(πR 2 ) in the range 0.006 Σ 0.07 g cm −2 . The uncertainties associated with each measurements are derived as in Traficante et al (2018b), that made an extensive analysis to evaluate the source of uncertainties for each parameter. A summary of the source parameters for all the 29 clumps used in this work are in Table 1.…”

Section: Clumps Analysismentioning

confidence: 99%

Multiscale dynamics in star-forming regions: the interplay between gravity and turbulence

Traficante

Fuller

Duarte-Cabral

et al. 2019

Monthly Notices of the Royal Astronomical Society

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In this work we investigate the interplay between gravity and turbulence at different spatial scales and in different density regimes. We analyze a sample of 70 µm quiet clumps that are divided into three surface density bins and we compare the dynamics of each group with the dynamics of their respective filaments. The densest clumps form within the densest filaments on average, and they have the highest value of the velocity dispersion. The kinetic energy is transferred from the filaments down to the clumps most likely through a turbulent cascade, but we identify a critical value of the surface density, Σ ≃ 0.1 g cm −2 , above which the dynamics changes from being mostly turbulent-driven to mostly gravity-driven. The scenario we obtain from our data is a continuous interplay between turbulence and gravity, where the former creates structures at all scales and the latter takes the lead when the critical surface density threshold is reached. In the densest filaments this transition can occur at the parsec, or even larger scales, leading to a global collapse of the whole region and most likely to the formation of the massive objects.

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“…This happens because a high velocity dispersion does not only imply internal turbulence, but it can also be due to gravitational contraction. Therefore this criterion possibly excludes also collapsing cores (Traficante et al 2018). The effect is more pronounced in run M, where the cutoff affects many high-mass cores.…”

Section: Core Mass Spectramentioning

confidence: 99%

Core and stellar mass functions in massive collapsing filaments

Ntormousi

Hennebelle

2019

A&A

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Context. The connection between the pre-stellar core mass function (CMF) and the stellar initial mass function (IMF) lies at the heart of all star formation theories, but it is inherently observationally unreachable. Aims. In this paper we aim to elucidate the earliest phases of star formation with a series of high-resolution numerical simulations that include the formation of sinks from high-density clumps. In particular, we focus on the transition from cores to sink particles within a massive molecular filament, and work towards identifying the factors that determine the shape of the CMF and the IMF. Methods. We compare the CMF and IMF between magnetized and unmagnetized simulations, and between different resolutions. In order to study the effect of core stability, we apply different selection criteria according to the virial parameter and the mass-to-flux ratio of the cores. Results. We find that, in all models, selecting cores based on their kinematic virial parameter tends to exclude collapsing objects, because they host high velocity dispersions. Selecting only the thermally unstable magnetized cores, we observe that their mass-to-flux ratio spans almost two orders of magnitude for a given mass. We also see that, when magnetic fields are included, the CMF peaks at higher core mass values with respect to a pure hydrodynamical simulation. Nonetheless, all models produce sink mass functions with a high-mass slope consistent with Salpeter. Finally, we examine the effects of resolution and find that, in these isothermal simulations, even models with very high dynamical range fail to converge in the mass function. Conclusions. Our main conclusion is that, although the resulting CMFs and IMFs have similar slopes in all simulations, the cores have slightly different sizes and kinematical properties when a magnetic field is included, and this affects their gravitational stability. Nonetheless, a core selection based on the mass-to-flux ratio is not enough to alter the shape of the CMF, if we do not take thermal stability into account. Finally, we conclude that extreme care should be given to resolution issues when studying sink formation with an isothermal equation of state, since with each increase in resolution, fragmentation continues to smaller scales in a self-similar way.

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Testing the Larson relations in massive clumps

Cited by 74 publications

References 80 publications

Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey

Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey

Multiscale dynamics in star-forming regions: the interplay between gravity and turbulence

Core and stellar mass functions in massive collapsing filaments

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