A Catalog of H
                    <scp>i</scp>
                    Clouds in the Large Magellanic Cloud

Kim, Sungeun; Rosolowsky, Erik; Lee, Youngung; Kim, Y; Jung, Yoonhyuk; Dopita, Michael A.; Elmegreen, Bruce G.; Freeman, K. C.; Sault, R. J.; Kesteven, Michael; McConnell, D.; Chu, You‐Hua

doi:10.1086/518126

Cited by 35 publications

(59 citation statements)

References 43 publications

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“…Although a straightforward comparison and therefore conclusion should be taken with care at this stage as the present work focuses on HI and does treat neither the formation of H 2 nor the formation of the CO molecule, the universality of the mass spectrum that we observed in our simulations suggests that these processes probably do not affect the mass spectrum significantly. We also note that in a recent study Kim et al (2007) inferred similar values for the HI clouds in the small magellanic cloud. But the mass of these clouds (10 4−6 solar masses) is much larger than the mass of our simulated clouds.…”

Section: Fig 12 Same Assupporting

confidence: 79%

“…Thus, size and mass spectrum in particular, cannot be easily computed. Extragalactic studies such as the one performed by Kim et al (2007) can get rid of this difficulty, but the scales that one can probe in nearby galaxies is much larger than the ones tackled in our simulations. On the other hand our results are not restricted to 2-phase flows since isothermal and barotropic cases are also considered.…”

Section: Relevance Of Comparison With Observationsmentioning

confidence: 92%

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On the structure of the turbulent interstellar clouds

Audit¹,

Hennebelle

2010

A&A

103

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Context. It is well established that the atomic interstellar hydrogen is filling the galaxies and constitutes the building blocks of molecular clouds. Aims. To understand the formation and the evolution of molecular clouds, it is necessary to investigate the dynamics of turbulent and thermally bistable as well as barotropic flows. Methods. We perform high resolution 3-dimensional hydrodynamical simulations of 2-phase, isothermal and polytropic flows. Results. We compare the density probability distribution function (PDF) and Mach number density relation in the various simulations and conclude that 2-phase flows behave rather differently than polytropic flows. We also extract the clumps and study their statistical properties such as the mass spectrum, mass-size relation and internal velocity dispersion. In each case, it is found that the behavior is well represented by a simple power law. While the various exponents inferred are very similar for the 2-phase, isothermal and polytropic flows, we nevertheless find significant differences, as for example the internal velocity dispersion, which is smaller for 2-phase flows. Conclusions. The structure statistics are very similar to what has been inferred from observations, in particular the mass spectrum, the mass-size relation and the velocity dispersion-size relation are all power laws whose indices well agree with the observed values. Our results suggest that in spite of various statistics being similar for 2-phase and polytropic flows, they nevertheless present significant differences, stressing the necessity to consider the proper thermal structure of the interstellar atomic hydrogen for computing its dynamics as well as the formation of molecular clouds.

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Section: Fig 12 Same Assupporting

confidence: 79%

Section: Relevance Of Comparison With Observationsmentioning

confidence: 92%

On the structure of the turbulent interstellar clouds

Audit¹,

Hennebelle

2010

A&A

103

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“…This means that we may not be tracing exactly the same gas. However, observations of the atomic gas have also been performed in external galaxies as the LMC (Kim et al 2007) and revealed A70, page 12 of 22 similar behaviour (though different numbers are obviously inferred). In principle structures should be identified in the same way that observers proceed.…”

Section: Structure Formationmentioning

confidence: 92%

Structure distribution and turbulence in self-consistently supernova-driven ISM of multiphase magnetized galactic discs

Iffrig

Hennebelle

2017

A&A

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Context. Galaxy evolution and star formation are two multi-scale problems tightly linked to each other. Aims. We aim to describe simultaneously the large-scale evolution widely induced by the feedback processes and the details of the gas dynamics that controls the star formation process through gravitational collapse. This is a necessary step in understanding the interstellar cycle, which triggers galaxy evolution. Methods. We performed a set of three-dimensional high-resolution numerical simulations of a turbulent, self-gravitating and magnetized interstellar medium within a 1 kpc stratified box with supernova feedback correlated with star-forming regions. In particular, we focussed on the role played by the magnetic field and the feedback on the galactic vertical structure, the star formation rate (SFR) and the flow dynamics. For this purpose we have varied their respective intensities. We extracted properties of the dense clouds arising from the turbulent motions and compute power spectra of various quantities. Results. Using a distribution of supernovae sufficiently correlated with the dense gas, we find that supernova explosions can reproduce the observed SFR, particularly if the magnetic field is on the order of a few µG. The vertical structure, which results from a dynamical and an energy equilibrium is well reproduced by a simple analytical model, which allows us to roughly estimate the efficiency of the supernovae in driving the turbulence in the disc to be rather low, of the order of 1.5%. Strong magnetic fields may help to increase this efficiency by a factor of between two and three. To characterize the flow we compute the power spectra of various quantities in 3D but also in 2D in order to account for the stratification of the galactic disc. We find that within our setup, the compressive modes tend to dominate in the equatorial plane, while at about one scale height above it, solenoidal modes become dominant. We measured the angle between the magnetic and velocity fields and we conclude that they tend to be well aligned particularly at high magnetization and lower feedback. Finally, the dense structures present scaling relations that are reminiscent of the observational ones. The virial parameter is typically larger than 10 and shows a large spread of masses below 1000 M . For masses larger than 10 4 M , its value tends to a few. Conclusions. Using a relatively simple scheme for the supernova feedback, which is self-consistently proportional to the SFR and spatially correlated to the star formation process, we reproduce a stratified galactic disc that presents reasonable scale height, SFR as well as a cloud distribution with characteristics close to the observed ones.

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“…One would also then expect to see a similar lopsidedness in the distribution of the HI clouds in the LMC plane. We have plotted the HI clouds using the data from Kim et al (2007) in the LMC plane in Fig. 11.…”

Section: Comparison With Hi Clouds and Star Clustersmentioning

confidence: 99%

The recent star-formation history of the Large and Small Magellanic Clouds

Indu

Subramaniam

2011

A&A

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Aims. Recent interactions between the Large and the Small Magellanic Clouds (LMC and SMC) and the Milky Way can be understood by studying their recent star formation history. This study aims to detect any directional or propagating star formation in the last 500 Myr. Methods. We traced the age of the last star-formation event (LSFE) in the inner Large and Small Magellanic Cloud (L&SMC) using the photometric data in V and I passbands from the Optical Gravitational Lensing Experiment (OGLE-III) and the Magellanic Cloud Photometric Survey (MCPS). The LSFE is estimated from the main sequence turn-off point in the color-magnitude diagram (CMD) of a subregion. After correcting for extinction, the turn-off magnitude is converted to age, which represents the LSFE in a region.Results. The spatial distribution of the age of the LSFE shows that the star-formation has shrunk to within the central regions in the last 100 Myr in both the galaxies. The location as well as age of LSFE is found to correlate well with those of the star cluster in both the Clouds. The SMC map shows two separate concentrations of young star-formation, one near the center and the other near the wing. We detect peaks of star-formation at 0-10 Myr and 90-100 Myr in the LMC, and 0-10 Myr and 50-60 Myr in the SMC. The quenching of star-formation in the LMC is found to be asymmetric with respect to the optical center such that most of the young star forming regions are located to the north and east. On deprojecting the data onto the LMC plane, the recent star-formation appears to be stretched in the northeast direction and the HI gas is found to be distributed preferentially in the north. We found that the centroid is shifted to the north during the time interval 200-40 Myr, whereas it is found to have shifted to the northeast in the last 40 Myr. In the SMC, we detect a shift in the centroid of the population younger than 500 Myr and as young as 40 Myr in the direction of the LMC. Conclusions. We propose that the HI gas in the LMC has been pulled to the north of the LMC in the last 200 Myr because of the gravitational attraction of our Galaxy at the time of perigalactic passage. The shifted HI gas was preferentially compressed in the north during the time interval 200-40 Myr and in the northeast in the last 40 Myr, owing to the motion of the LMC in the Galactic halo. The recent star-formation in the SMC is due to the combined gravitational effect of the LMC and the perigalactic passage.

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A Catalog of H i Clouds in the Large Magellanic Cloud

Cited by 35 publications

References 43 publications

On the structure of the turbulent interstellar clouds

On the structure of the turbulent interstellar clouds

Structure distribution and turbulence in self-consistently supernova-driven ISM of multiphase magnetized galactic discs

The recent star-formation history of the Large and Small Magellanic Clouds

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