The cosmological simulation code gadget-2

Springel, Volker

doi:10.1111/j.1365-2966.2005.09655.x

Cited by 6,452 publications

(6,470 citation statements)

References 118 publications

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“…For these simulations, we employed a modified version of Gadget-2 (Springel 2005) that uses only Table 1. Labels and specifics of the simulations used in this work.…”

Section: Wdm Simulationsmentioning

confidence: 99%

The properties of cosmic velocity fields

Hahn¹,

Angulo²,

Abel³

2015

Mon. Not. R. Astron. Soc.

125

170

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Understanding the velocity field is very important for modern cosmology: it gives insights to structure formation in general, and also its properties are crucial ingredients in modelling redshift-space distortions and in interpreting measurements of the kinetic Sunyaev-Zeldovich effect. Unfortunately, characterising the velocity field in cosmological N -body simulations is inherently complicated by two facts: i) The velocity field becomes manifestly multi-valued after shell-crossing and has discontinuities at caustics. This is due to the collisionless nature of dark matter. ii) N -body simulations sample the velocity field only at a set of discrete locations, with poor resolution in low-density regions. In this paper, we discuss how the associated problems can be circumvented by using a phase-space interpolation technique. This method provides extremely accurate estimates of the cosmic velocity fields and its derivatives, which can be properly defined without the need of the arbitrary "coarse-graining" procedure commonly used. We explore in detail the configuration-space properties of the cosmic velocity field on very large scales and in the highly nonlinear regime. In particular, we characterise the divergence and curl of the velocity field, present their one-point statistics, analyse the Fourier-space properties and provide fitting formulae for the velocity divergence bias relative to the non-linear matter power spectrum. We furthermore contrast some of the interesting differences in the velocity fields of warm and cold dark matter models. We anticipate that the high-precision measurements carried out here will help to understand in detail the dynamics of dark matter and the structures it forms.

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“…For these simulations, we employed a modified version of Gadget-2 (Springel 2005) that uses only Table 1. Labels and specifics of the simulations used in this work.…”

Section: Wdm Simulationsmentioning

confidence: 99%

The properties of cosmic velocity fields

Hahn¹,

Angulo²,

Abel³

2015

Mon. Not. R. Astron. Soc.

125

170

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“…All simulations in Table 3.1 except for the one denoted as Euler were run using the publicly available Tree-Particle Mesh Smoothed Particle Hydrodynamics (SPH) GADGET-II code [54]. The fiducial simulation uses a box of 60 comoving h −1 Mpc and 2 × 512 3 particles (for the total of gas and dark matter).…”

Section: Sph Simulationsmentioning

confidence: 99%

The non-linear power spectrum of the Lyman alpha forest

Arinyo-i-Prats

Miralda-Escudé

Viel

et al. 2015

J. Cosmol. Astropart. Phys.

133

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Abstract. The Lyman alpha forest power spectrum has been measured on large scales by the BOSS survey in SDSS-III at z ∼ 2.3, has been shown to agree well with linear theory predictions, and has provided the first measurement of Baryon Acoustic Oscillations at this redshift. However, the power at small scales, affected by non-linearities, has not been well examined so far. We present results from a variety of hydrodynamic simulations to predict the redshift space non-linear power spectrum of the Lyα transmission for several models, testing the dependence on resolution and box size. A new fitting formula is introduced to facilitate the comparison of our simulation results with observations and other simulations. The non-linear power spectrum has a generic shape determined by a transition scale from linear to non-linear anisotropy, and a Jeans scale below which the power drops rapidly. In addition, we predict the two linear bias factors of the Lyα forest and provide a better physical interpretation of their values and redshift evolution. The dependence of these bias factors and the non-linear power on the amplitude and slope of the primordial fluctuations power spectrum, the temperature-density relation of the intergalactic medium, and the mean Lyα transmission, as well as the redshift evolution, is investigated and discussed in detail. A preliminary comparison to the observations shows that the predicted redshift distortion parameter is in good agreement with the recent determination of Blomqvist et al., but the density bias factor is lower than observed. We make all our results publicly available in the form of tables of the non-linear power spectrum that is directly obtained from all our simulations, and parameters of our fitting formula.

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“…Our simulation code is the parallel Tree-Particle Mesh code, GADGET-2 (Springel 2005). We use N = 512 3 particles in a comoving volume of L = 10 h −1 Mpc on a side.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Structure of dark matter halos in warm dark matter models and in models with long-lived charged massive particles

Kamada

Yoshida

Kohri

et al. 2013

J. Cosmol. Astropart. Phys.

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We study the formation of non-linear structures in Warm Dark Matter (WDM) models and in a Long-Lived Charged Massive Particle (CHAMP) model. CHAMPs with a decay lifetime of about 1 yr induce characteristic suppression in the matter power spectrum at subgalactic scales through acoustic oscillations in the thermal background. We explore structure formation in such a model. We also study three WDM models, where the dark matter particles are produced through the following mechanisms: i) WDM particles are produced in the thermal background and then kinematically decoupled; ii) WDM particles are fermions produced by the decay of thermal heavy bosons; and iii) WDM particles are produced by the decay of non-relativistic heavy particles. We show that the linear matter power spectra for the three models are all characterised by the comoving Jeans scale at the matter-radiation equality. Furthermore, we can also describe the linear matter power spectrum for the Long-Lived CHAMP model in terms of a suitably defined characteristic cut-off scale k Ch , similarly to the WDM models. We perform large cosmological N -body simulations to study the non-linear growth of structures in these four models. We compare the halo mass functions, the subhalo mass functions, and the radial distributions of subhalos in simulated Milky Way-size halos. For the characteristic cut-off scale k cut = 51 h Mpc −1 , the subhalo abundance -2 -(∼ 10 9 M sun ) is suppressed by a factor of ∼ 10 compared with the standard ΛCDM model. We then study the models with k cut ≃ 51, 410, 820 h Mpc −1 , and confirm that the halo and the subhalo abundances and the radial distributions of subhalos are indeed similar between the different WDM models and the Long-Lived CHAMP model. The result suggests that the cut-off scale k cut not only characterises the linear power spectra but also can be used to predict the non-linear clustering properties. The radial distribution of subhalos in Milky Way-size halos is consistent with the observed distribution for k cut ∼ 50 − 800 h Mpc −1 ; such models resolve the so-called "missing satellite problem".

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The cosmological simulation code gadget-2

Cited by 6,452 publications

References 118 publications

The properties of cosmic velocity fields

The properties of cosmic velocity fields

The non-linear power spectrum of the Lyman alpha forest

Structure of dark matter halos in warm dark matter models and in models with long-lived charged massive particles

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