Mathematical model of a Hot Dry Rock system   总被引：1，自引：0，他引：1  

Norbert Heuer  Tassilo Küpper  Dirk Windelberg 《Geophysical Journal International》1991,105(3):659-664

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Including star formation and supernova feedback within cosmological simulations of galaxy formation   总被引：1，自引：0，他引：1  

Scott T.Kay  Frazer R.Pearce  Carlos S.Frenk  AdrianJenkins 《Monthly notices of the Royal Astronomical Society》2002,330(1):113-128

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板块构造图的制图理论与方法探讨     

高延林 《青海国土经略》2001,(2)

通过编制区域性1:300万“青藏高原板块构造图”和1:50万“柴达木北缘板块构造地质图”的体会,并结合国内学者对这两份图件的审查意见及建议,重点讨论有关区域性板块构造图编制的理论与方法,供区域地质工作者参考。  相似文献   

Consistent β values from density–density and velocity–velocity comparisons     

Saleem Zaroubi  Enzo Branchini  Yehuda Hoffman  Luiz N. da Costa 《Monthly notices of the Royal Astronomical Society》2002,336(4):1234-1246

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Cosmological parameters from velocities, cosmic microwave background and supernovae     

S. L. Bridle  I. Zehavi  A. Dekel  O. Lahav  M. P. Hobson  A. N. Lasenby 《Monthly notices of the Royal Astronomical Society》2001,321(2):333-340

We compare and combine likelihood functions of the cosmological parameters Ω_m, h and σ ₈, from peculiar velocities, cosmic microwave background (CMB) and type Ia supernovae. These three data sets directly probe the mass in the Universe, without the need to relate the galaxy distribution to the underlying mass via a 'biasing' relation. We include the recent results from the CMB experiments BOOMERANG and MAXIMA-1. Our analysis assumes a flat Λ cold dark matter (ΛCDM) cosmology with a scale-invariant adiabatic initial power spectrum and baryonic fraction as inferred from big-bang nucleosynthesis. We find that all three data sets agree well, overlapping significantly at the 2 σ level. This therefore justifies a joint analysis, in which we find a joint best-fitting point and 95 per cent confidence limits of     (0.17,0.39),     (0.64,0.86) and     (0.98,1.37). In terms of the natural parameter combinations for these data     (0.40,0.73),     (0.16,0.27). Also for the best-fitting point,     and the age of the Universe is 13.2 Gyr.  相似文献   

Merger histories in warm dark matter structure formation scenarios     

Alexander Knebe  Julien E. G. Devriendt  Asim Mahmood  Joseph Silk 《Monthly notices of the Royal Astronomical Society》2002,329(4):813-828

Observations on galactic scales seem to be in contradiction with recent high-resolution N -body simulations. This so-called cold dark matter (CDM) crisis has been addressed in several ways, ranging from a change in fundamental physics by introducing self-interacting cold dark matter particles to a tuning of complex astrophysical processes such as global and/or local feedback. All these efforts attempt to soften density profiles and reduce the abundance of satellites in simulated galaxy haloes. In this paper, we explore a different approach that consists of filtering the dark matter power spectrum on small scales, thereby altering the formation history of low-mass objects. The physical motivation for damping these fluctuations lies in the possibility that the dark matter particles have a different nature, i.e. are warm (WDM) rather than cold. We show that this leads to some interesting new results in terms of the merger history and large-scale distribution of low-mass haloes, compared with the standard CDM scenario. However, WDM does not appear to be the ultimate solution, in the sense that it is not able to fully solve the CDM crisis, even though one of the main drawbacks, namely the abundance of satellites, can be remedied. Indeed, the cuspiness of the halo profiles still persists, at all redshifts, and for all haloes and sub-haloes that we investigated. Despite the persistence of the cuspiness problem of DM haloes, WDM seems to be still worth taking seriously, as it alleviates the problems of over-abundant sub-structures in galactic haloes and possibly the lack of angular momentum of simulated disc galaxies. WDM also lessens the need to invoke strong feedback to solve these problems, and may provide a natural explanation of the clustering properties and ages of dwarfs.  相似文献   

Reflection at large distance from the central engine in Seyferts     

Julien Malzac  Pierre-Olivier Petrucci 《Monthly notices of the Royal Astronomical Society》2002,336(4):1209-1216

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Testing tidal-torque theory – I. Spin amplitude and direction     

Cristiano Porciani  Avishai Dekel  Yehuda Hoffman 《Monthly notices of the Royal Astronomical Society》2002,332(2):325-338

We evaluate the success of linear tidal-torque theory (TTT) in predicting galactic-halo spin using a cosmological N -body simulation with thousands of well-resolved haloes. The protohaloes are identified by tracing today's haloes back to the initial conditions. The TTT predictions for the protohaloes match, on average, the spin amplitudes of the virialized haloes of today, if linear growth is assumed until ∼ t ₀/3, or  55–70  per cent of the halo effective turn-around time. This makes it a useful qualitative tool for understanding certain average properties of galaxies, such as total spin and angular momentum distribution within haloes, but with a random scatter of the order of the signal itself. Non-linear changes in spin direction cause a mean error of ∼50° in the TTT prediction at t ₀, such that the linear spatial correlations of spins on scales ≥1  h ⁻¹ Mpc are significantly weakened by non-linear effects. This questions the usefulness of TTT for predicting intrinsic alignments in the context of gravitational lensing. We find that the standard approximations made in TTT, including a second-order expansion of the Zel'dovich potential and a smoothing of the tidal field, provide close-to-optimal results.  相似文献   

论提高环境水文地质图件制图工艺     

吴敬杰 《河南国土资源》1994,(1)

近年来，地图制图理论有了较快的发展，如何将信息传输和视觉感受等方面的研究成果运用于环境水文地质图的编制，是制图工作者和专业人员共同关注的一个重要问题。本文以编制城市环境水文地质图为例，就制图过程中的一些原则和方法作一探讨。  相似文献   

Surfaces of section in the Miranda-Umbriel 3:1 inclination problem     

Michèle Moons  Jacques Henrard 《Celestial Mechanics and Dynamical Astronomy》1994,59(2):129-148

The recent numerical simulations of Tittemore and Wisdom (1988, 1989, 1990) and Dermottet al. (1988), Malhotra and Dermott (1990) concerning the tidal evolution through resonances of some pairs of Uranian satellites have revealed interesting dynamical phenomena related to the interactions between close-by resonances. These interactions produce chaotic layers and strong secondary resonances. The slow evolution of the satellite orbits in this dynamical landscape is responsible for temporary capture into resonance, enhancement of eccentricity or inclination and subsequent escape from resonance. The present contribution aims at developing analytical tools for predicting the location and size of chaotic layers and secondary resonances. The problem of the 3:1 inclination resonance between Miranda and Umbriel is analysed.  相似文献