scholarly journals Photoelectric heating effects on the evolution of luminous disc galaxies

2020 ◽  
Vol 498 (2) ◽  
pp. 2075-2088
Author(s):  
Omima Osman ◽  
Kenji Bekki ◽  
Luca Cortese
Keyword(s):  
Star Formation ◽  
Massive Galaxies ◽  
Heating Effects ◽  
Central Regions ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Excess Heating ◽  
Specific Implementation ◽  
Dust Evolution ◽  
Gas Fractions

ABSTRACT Photoelectric heating (PEH) influences the temperature and density of the interstellar medium (ISM), potentially also affecting star formation. PEH is expected to have a stronger effect on massive galaxies, as they host larger dust reservoirs compared to dwarf systems. Accordingly, in this paper, we study PEH effects in Milky Way-like galaxies using a smoothed particle hydrodynamics code, which self-consistently implements the evolution of the gas, dust, and interstellar radiation field. Dust evolution includes dust formation by stars, destruction by SNe, and growth in dense media. We find that PEH suppresses star formation due to the excess heating that reduces the ISM density. This suppression is seen across the entire range of gas fractions, star-formation recipes, dust models, and PEH efficiencies investigated by our code. The suppression ranges from negligible values to approximately a factor of five depending on the specific implementation. Galaxy models having higher gas fractions experience higher star-formation suppression. The adopted dust model also alters the extent of star-formation suppression. Moreover, when PEH is switched on, galaxy models show higher gas outflow rates and have higher loading factors, indicative of enhanced SNe feedback. In gas-rich models (i.e. a gas fraction of 0.5), we also find that PEH suppresses the formation of disc clumps via violent disc instabilities, and thus suppresses bulge formation via clump migration to the central regions.

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 Quasar Metal Abundances & Host Galaxy Evolution

2009 ◽  
Vol 5 (S265) ◽  
pp. 171-178
Author(s):  
Fred Hamann ◽  
Leah E. Simon
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
High Redshift ◽  
Big Bang ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Central Regions ◽  
Metal Abundances ◽  
The Big Bang

AbstractHigh-redshift quasars provide a unique glimpse into the early evolution of massive galaxies. The physical processes that trigger major bursts of star formation in quasar host galaxies (mergers and interactions) probably also funnel gas into the central regions to grow the super-massive black holes (SMBHs) and ignite the luminous quasar phenomenon. The globally dense environments where this occurs were probably also among the first to collapse and manufacture stars in significant numbers after the big bang. Measurements of the elemental abundances near quasars place important constraints on the nature, timing and extent of this star formation. A variety of studies using independent emission and absorption line diagnostics have shown that quasar environments have gas-phase metallicities that are typically a few times solar at all observed redshifts. These results are consistent with galaxy evolution scenarios in which large amounts of star formation (e.g., in the central regions) precede the visibly bright quasar phase. An observed trend for higher metallicities in more luminmous quasars (powered by more massive SMBHs) is probably tied to the well-known mass–metallicity relation among ordinary galaxies. This correlation and the absence of a trend with redshift indicate that mass is a more important parameter in the evolution than the time elapsed since the big bang.

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 Stellar and weak lensing profiles of massive galaxies in the Hyper-Suprime Cam survey and in hydrodynamic simulations

2020 ◽  
Vol 500 (1) ◽  
pp. 432-447
Author(s):  
Felipe Ardila ◽  
Song Huang ◽  
Alexie Leauthaud ◽  
Benedikt Diemer ◽  
Annalisa Pillepich ◽  
...  
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Mass Scale ◽  
Ex Situ ◽  
Weak Lensing ◽  
Mass Relation ◽  
Massive Galaxies ◽  
Physical Scale ◽  
Central Regions ◽  
Stellar Masses

ABSTRACT We perform a consistent comparison of the mass and mass profiles of massive (M⋆ > 1011.4 M⊙) central galaxies at z ∼ 0.4 from deep Hyper Suprime-Cam (HSC) observations and from the Illustris, TNG100, and Ponos simulations. Weak lensing measurements from HSC enable measurements at fixed halo mass and provide constraints on the strength and impact of feedback at different halo mass scales. We compare the stellar mass function (SMF) and the Stellar-to-Halo Mass Relation (SHMR) at various radii and show that the radius at which the comparison is performed is important. In general, Illustris and TNG100 display steeper values of α where $M_{\star } \propto M_{\rm vir}^{\alpha }$. These differences are more pronounced for Illustris than for TNG100 and in the inner rather than outer regions of galaxies. Differences in the inner regions may suggest that TNG100 is too efficient at quenching in situ star formation at Mvir ≃ 1013 M⊙ but not efficient enough at Mvir ≃ 1014 M⊙. The outer stellar masses are in excellent agreement with our observations at Mvir ≃ 1013 M⊙, but both Illustris and TNG100 display excess outer mass as Mvir ≃ 1014 M⊙ (by ∼0.25 and ∼0.12 dex, respectively). We argue that reducing stellar growth at early times in $M_\star \sim 10^{9-10} \, \mathrm{M}_{\odot }$ galaxies would help to prevent excess ex-situ growth at this mass scale. The Ponos simulations do not implement AGN feedback and display an excess mass of ∼0.5 dex at r < 30 kpc compared to HSC which is indicative of overcooling and excess star formation in the central regions. The comparison of the inner profiles of Ponos and HSC suggests that the physical scale over which the central AGN limits star formation is r ≲ 20 kpc. Joint comparisons between weak lensing and galaxy stellar profiles are a direct test of whether simulations build and deposit galaxy mass in the correct dark matter haloes and thereby provide powerful constraints on the physics of feedback and galaxy growth. Our galaxy and weak lensing profiles are publicly available to facilitate comparisons with other simulations.

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