The implications of dust for high-redshift protogalaxies and the formation of binary disks

Latif, Muhammad; Schleicher, Dominik R. G.; Spaans, Marco

doi:10.1051/0004-6361/201118295

Cited by 22 publications

(20 citation statements)

References 87 publications

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“…These strong seed fields could potentially lead to the generation of large‐scale coherent magnetic fields on scales much larger than the scale of turbulence (in our case on scales k / k J ≪ 1) via large‐scale dynamo mechanisms (Ruzmaikin, Sokolov & Shukurov 1988; Hanasz, Wóltański & Kowalik 2009; Jedamzik & Sigl 2011). Evidence for the presence of global rotation and disc structures has been found in recent simulations by Latif et al (2012). The implications of such coherent magnetic fields have been previously explored in the works of Pudritz & Silk (1989) and Tan & Blackman (2004).…”

Section: Discussionmentioning

confidence: 84%

Magnetic field amplification during gravitational collapse - influence of turbulence, rotation and gravitational compression

Sur

Federrath

Schleicher

et al. 2012

Monthly Notices of the Royal Astronomical Society

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We study the influence of initial conditions on the magnetic field amplification during the collapse of a magnetized gas cloud. We focus on the dependence of the growth and saturation level of the dynamo‐generated field on the turbulent properties of the collapsing cloud. In particular, we explore the effect of varying the initial strength and injection scale of turbulence and the initial uniform rotation of the collapsing magnetized cloud. In order to follow the evolution of the magnetic field in both the kinematic and the non‐linear regime, we choose an initial field strength of with the magnetic to kinetic energy ratio, Em/Ek∼ 10−4. Both gravitational compression and the small‐scale dynamo initially amplify the magnetic field. Further into the evolution, the dynamo‐generated magnetic field saturates but the total magnetic field continues to grow because of compression. The saturation of the small‐scale dynamo is marked by a change in the slope of B/ρ2/3 and by a shift in the peak of the magnetic energy spectrum from small scales to larger scales. For the range of initial Mach numbers explored in this study, the dynamo growth rate increases as the Mach number increases from vrms/cs∼ 0.2 to 0.4 and then starts decreasing from vrms/cs∼ 1.0. We obtain saturation values of Em/Ek= 0.2–0.3 for these runs. Simulations with different initial injection scales of turbulence also show saturation at similar levels. For runs with different initial rotation of the cloud, the magnetic energy saturates at Em/Ek∼ 0.2–0.4 of the equipartition value. The overall saturation level of the magnetic energy, obtained by varying the initial conditions, is in agreement with previous analytical and numerical studies of small‐scale dynamo action where turbulence is driven by an external forcing instead of gravitational collapse.

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Section: Discussionmentioning

confidence: 84%

Magnetic field amplification during gravitational collapse - influence of turbulence, rotation and gravitational compression

Sur

Federrath

Schleicher

et al. 2012

Monthly Notices of the Royal Astronomical Society

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“…This eventually drives the formation and build-up of ices. We follow Hollenbach et al (1991), also mentioned in Latif et al (2012), but with some adaptations of our own. The initial estimate of the dust temperature, T d,i , which incorporates the attenuated incident UV radiation field, the cosmic microwave background temperature T CMB = 2.725 K, and the infrared dust emission, is defined as…”

Section: Dust Temperaturementioning

confidence: 99%

Interplay of gas and ice during cloud evolution

Hocuk

Cazaux

2015

A&A

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During the evolution of diffuse clouds to molecular clouds, gas-phase molecules freeze out on surfaces of small dust particles to form ices. On dust surfaces, water is the main constituent of the icy mantle in which a complex chemistry is taking place. We aim to study the formation pathways and the composition of the ices throughout the evolution of diffuse clouds. For this purpose, we used time-dependent rate equations to calculate the molecular abundances in the gas phase and on solid surfaces (onto dust grains). We fully considered the gas-dust interplay by including the details of freeze-out, chemical and thermal desorption, and the most important photo-processes on grain surfaces. The difference in binding energies of chemical species on bare and icy surfaces was also incorporated into our equations. Using the numerical code flash, we performed a hydrodynamical simulation of a gravitationally bound diffuse cloud and followed its contraction. We find that while the dust grains are still bare, water formation is enhanced by grain surface chemistry that is subsequently released into the gas phase, enriching the molecular medium. The CO molecules, on the other hand, tend to gradually freeze out on bare grains. This causes CO to be well mixed and strongly present within the first ice layer. Once one monolayer of water ice has formed, the binding energy of the grain surface changes significantly, and an immediate and strong depletion of gas-phase water and CO molecules occurs. While hydrogenation converts solid CO into formaldehyde (H 2 CO) and methanol (CH 3 OH), water ice becomes the main constituent of the icy grains. Inside molecular clumps formaldehyde is more abundant than water and methanol in the gas phase, owing its presence in part to chemical desorption.

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“…In the presence of such accretion rates, feedback can be expected to be weak (Hosokawa et al 2012; Schle- icher et al 2013) and does not impede the accretion. Indeed, even trace amounts of dust, corresponding to 10 −5 − 10 −3 times the dust-to-gas ratio in the solar neighborhood, may already trigger strong cooling and fragmentation at high densities (Schneider et al 2004;Omukai et al 2005), but also stimulate the formation of molecular hydrogen at low to moderate densities (Cazaux & Spaans 2009;Latif et al 2012). The extremely metal poor star SDSS J1029151+172927 (Caffau et al 2011) shows chemical abundances at which metal line coolant is inefficient, and where only trace amounts of dust grains were able to trigger cooling and fragmentation Schneider et al 2012) 12 .…”

Section: Concluding Remarks and Open Problemsmentioning

confidence: 99%

Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

2014

Self Cite

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The large-scale structure of the Universe formed from initially small perturbations in the cosmic density field, leading to galaxy clusters with up to 10 15 M at the present day. Here, we review the formation of structures in the Universe, considering the first primordial galaxies and the most massive galaxy clusters as extreme cases of structure formation where fundamental processes such as gravity, turbulence, cooling and feedback are particularly relevant. The first non-linear objects in the Universe formed in dark matter halos with 10 5 − 10 8 M at redshifts 10 − 30, leading to the first stars and massive black holes. At later stages, larger scales became non-linear, leading to the formation of galaxy clusters, the most massive objects in the Universe. We describe here their formation via gravitational processes, including the self-similar scaling relations, as well as the observed deviations from such self-similarity and the related non-gravitational physics (cooling, stellar feedback, AGN). While on intermediate cluster scales the self-similar model is in good agreement with the observations, deviations from such self-similarity are apparent in the core regions, where numerical simulations do not reproduce the current observational results. The latter indicates that the interaction of different feedback processes may not be correctly accounted for in current simulations. Both in the most massive clusters of galaxies as well as during the formation of the first objects in the Universe, turbulent structures and shock waves appear to be common, suggesting them to be ubiquitous in the non-linear regime.

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The implications of dust for high-redshift protogalaxies and the formation of binary disks

Cited by 22 publications

References 87 publications

Magnetic field amplification during gravitational collapse - influence of turbulence, rotation and gravitational compression

Magnetic field amplification during gravitational collapse - influence of turbulence, rotation and gravitational compression

Interplay of gas and ice during cloud evolution

Large-Scale Structure Formation: From the First Non-linear Objects to Massive Galaxy Clusters

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