scholarly journals Star formation rate and metallicity of damped Lyman α absorbers in cosmological smoothed particle hydrodynamics simulations

2004 ◽  
Vol 348 (2) ◽  
pp. 435-450 ◽  
Author(s):  
K. Nagamine ◽  
V. Springel ◽  
L. Hernquist
Keyword(s):  
Star Formation ◽  
Smoothed Particle Hydrodynamics ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

scholarly journals Testing star formation rate indicators using galaxy merger simulations and radiative transfer

2009 ◽  
Vol 5 (S262) ◽  
pp. 257-260
Author(s):  
Christopher C. Hayward ◽  
Patrik Jonsson ◽  
Kai Noeske ◽  
Stijn Wuyts ◽  
T. J. Cox ◽  
...  
Keyword(s):  
Star Formation ◽  
Radiative Transfer ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Merging Galaxies ◽  
Formation History ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

AbstractWe discuss our ongoing project analyzing N-body/smoothed-particle hydrodynamics simulations of isolated and merging galaxies, performed using GADGET-2 (Springel 2005), with the 3-D adaptive grid, polychromatic Monte Carlo radiative transfer code SUNRISE (Jonsson 2006). We apply commonly used UV, optical, and IR star formation rate (SFR) indicators to the integrated spectral energy distributions (SEDs) of the simulated galaxies in order to determine how well the SFR indicators recover the instantaneous SFR in the simulations. The models underlying each SFR indicator must necessarily make assumptions about physical properties of the galaxies, e.g., the star formation history (SFH), whereas all such properties are known in the simulations. This enables us to test and compare SFR indicators in a way that is complementary to observational studies. We present one preliminary result of interest: even after correcting the Hα luminosity for dust using the Calzetti et al. (2000) attenuation law the SFR is significantly underestimated for simulated galaxies with SFR ≳ 10 M⊙ yr−1.

scholarly journals Implementing and comparing sink particles in AMR and SPH

2010 ◽  
Vol 6 (S270) ◽  
pp. 425-428 ◽  
Author(s):  
Christoph Federrath ◽  
Robi Banerjee ◽  
Daniel Seifried ◽  
Paul C. Clark ◽  
Ralf S. Klessen
Keyword(s):  
Star Formation ◽  
Adaptive Mesh Refinement ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Particle Creation ◽  
Adaptive Mesh ◽  
Particle Properties ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Density Threshold

AbstractWe implemented sink particles in the Adaptive Mesh Refinement (AMR) code FLASH to model the gravitational collapse and accretion in turbulent molecular clouds and cores. Sink particles are frequently used to measure properties of star formation in numerical simulations, such as the star formation rate and efficiency, and the mass distribution of stars. We show that only using a density threshold for sink particle creation is insufficient in case of supersonic flows, because the density can exceed the threshold in strong shocks that do not necessarily lead to local collapse. Additional physical collapse indicators have to be considered. We apply our AMR sink particle module to the formation of a star cluster, and compare it to a Smoothed Particle Hydrodynamics (SPH) code with sink particles. Our comparison shows encouraging agreement of gas and sink particle properties between the AMR and SPH code.

scholarly journals Magnetic fields and Turbulence in Star Formation using Smoothed Particle Hydrodynamics

2010 ◽  
Vol 6 (S270) ◽  
pp. 169-177
Author(s):  
Daniel J. Price
Keyword(s):  
Star Formation ◽  
Mach Number ◽  
Magnetic Fields ◽  
Turbulent Flows ◽  
Smoothed Particle Hydrodynamics ◽  
Current State ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Relationship

AbstractFirstly, we give a historical overview of attempts to incorporate magnetic fields into the Smoothed Particle Hydrodynamics method by solving the equations of Magnetohydrodynamics (MHD), leading an honest assessment of the current state-of-the-art in terms of the limitations to performing realistic calculations of the star formation process. Secondly, we discuss the results of a recent comparison we have performed on simulations of driven, supersonic turbulence with SPH and Eulerian techniques. Finally we present some new results on the relationship between the density variance and the Mach number in supersonic turbulent flows, finding σ2ln ρ = ln(1 + b22 with b = 0.33 up to Mach 20, consistent with other numerical results at lower Mach number (Lemaster & Stone 2008) but inconsistent with observational constraints on σρ and in Taurus and IC5146.

scholarly journals UGC 7639: A Dwarf Galaxy in the Canes Venatici I Cloud

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
L. M. Buson ◽  
D. Bettoni ◽  
P. Mazzei ◽  
G. Galletta
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Spectral Energy ◽  
Global Properties ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Formation And Evolution ◽  
Good Agreement

We want to get insight into the formation mechanism and the evolution of UGC 7639, a dwarf galaxy in the Canes Venatici I Cloud (CVnIC). We used archival multiwavelength data to constrain its global properties. Ultraviolet images show that UGC 7639 inner regions are composed mostly by young stellar populations. In addition, we used smoothed particle hydrodynamics simulations with chemophotometric implementation to account for its formation and evolution. UGC 7639 is an example of blue dwarf galaxy whose global properties are well matched by our multiwavelength approach, that is, a suitable approach to highlight the evolution also of these galaxies as a class. We found that the global properties of UGC 7639, namely, its total absolute B-band magnitude, its whole spectral energy distribution, and morphology, are well matched by an encounter with a system four times more massive than our target. Moreover, the current star formation rate of the simulated dwarf, ≈0.03 M⊙ yr−1, is in good agreement with our UV-based estimate. We derived a galaxy age of 8.6 Gyr. Following our simulation, the ongoing star formation will extinguish within 1.6 Gyr, thus leaving a red dwarf galaxy.

scholarly journals Damped Lyman-α Absorbers in Cosmological SPH Simulations: the “Metallicity Problem”

2005 ◽  
Vol 216 ◽  
pp. 266-273
Author(s):  
Kentaro Nagamine ◽  
Volker Springel ◽  
Lars Hernquist
Keyword(s):  
Star Formation ◽  
Cold Dark Matter ◽  
Mass Density ◽  
Formation Rate ◽  
Neutral Hydrogen ◽  
Galactic Winds ◽  
Particle Hydrodynamics ◽  
Order Of Magnitude ◽  
Smoothed Particle ◽  
Hydrogen Mass

We study the distribution of star formation rate (SFR) and metallicity of damped Lyman-α absorbers (DLAs) using cosmological smoothed particle hydrodynamics (SPH) simulations of the Λ cold dark matter (CDM) model. Our simulations include a phenomenological model for feedback by galactic winds which allows us to examine the effect of galactic outflows on the distribution of SFR and metallicity of DLAs. For models with strong galactic winds, we obtain good agreement with recent observations with respect to total neutral hydrogen mass density, NHI column-density distribution, abundance of DLAs, and for the distribution of SFR in DLAs. However, we also find that the median metallicity of simulated DLAs is higher than the values typically observed by nearly an order of magnitude. This discrepancy with observations could be due to shortcomings in the treatment of the supernova feedback or the multiphase structure of the gas in our current simulations. Recent observations by Wolfe et al. (2003a,b) seem to point to the same problem; i.e. the observed DLA metallicities are much lower than those expected from the (either observed or simulated) DLA star formation rates, a puzzle that has been known as the “missing metals”-problem for the globally averaged quantities.

scholarly journals Radiation Driven Implosion and Triggered Star Formation

2010 ◽  
Vol 6 (S270) ◽  
pp. 263-266
Author(s):  
T. G. Bisbas ◽  
A. P. Whitworth ◽  
R. Wünsch ◽  
D. A. Hubber ◽  
S. Walch
Keyword(s):  
Star Formation ◽  
Ionizing Radiation ◽  
Smoothed Particle Hydrodynamics ◽  
Critical Parameter ◽  
External Source ◽  
Incident Flux ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

AbstractWe present simulations of stable isothermal clouds exposed to ionizing radiation from a discrete external source, and identify the conditions that lead to Radiatively Driven Implosion and Star Formation. We use the Smoothed Particle Hydrodynamics code SEREN (Hubber et al. 2010) and the HEALPix-based photoionization algorithm described in Bisbas et al. (2009). We find that the incident ionizing flux is the critical parameter determining the evolution; high fluxes disperse the cloud, whereas low fluxes trigger star formation. We find a clear connection between the intensity of the incident flux and the parameters of star formation.

scholarly journals The role of collision speed, cloud density, and turbulence in the formation of young massive clusters via cloud–cloud collisions

2020 ◽  
Vol 499 (1) ◽  
pp. 1099-1115
Author(s):  
Kong You Liow ◽  
Clare L Dobbs
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Conveyor Belt ◽  
Giant Molecular Clouds ◽  
Formation Mode ◽  
Smoothed Particle ◽  
Hydrodynamical Simulations ◽  
Massive Clusters ◽  
Cloud Density

ABSTRACT Young massive clusters (YMCs) are recently formed astronomical objects with unusually high star formation rates. We propose the collision of giant molecular clouds (GMCs) as a likely formation mechanism of YMCs, consistent with the YMC conveyor-belt formation mode concluded by other authors. We conducted smoothed particle hydrodynamical simulations of cloud–cloud collisions and explored the effect of the clouds’ collision speed, initial cloud density, and the level of cloud turbulence on the global star formation rate and the properties of the clusters formed from the collision. We show that greater collision speed, greater initial cloud density and lower turbulence increase the overall star formation rate and produce clusters with greater cluster mass. In general, collisions with relative velocity ≳ 25 km s−1, initial cloud density ≳ 250 cm−3, and turbulence of ≈2.5 km s−1 can produce massive clusters with properties resembling the observed Milky Way YMCs.

Sign in / Sign up

Export Citation Format

Share Document