We present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly ...hierarchical. One advantage of these 'Dhaloes' over the commonly used friends-of-friends (FoF) haloes is that they retain their individual identity in the cases when FoF haloes are artificially merged by tenuous bridges of particles or by an overlap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi-analytic galaxy formation model, GALFORM. Applying the Dhalo construction to the ... cold dark matter Millennium II Simulation, we find that approximately 90 per cent of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10 per cent are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, ..., than FoF haloes. Approximately 80 per cent of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes, all three types have similar concentration-M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions. (ProQuest: ... denotes formulae/symbols omitted.)
We present distributions of orbital parameters of infalling satellites of Λ cold dark matter (ΛCDM) haloes in the mass range 1012–1014 M⊙, which represent the initial conditions for the subsequent ...evolution of substructures within the host halo. We use merger trees constructed in a high-resolution cosmological N-body simulation to trace satellite haloes, and identify the time of infall. We find significant trends in the distribution of orbital parameters with both the host halo mass and the ratio of satellite-to-host halo masses. For all host halo masses, satellites whose infall mass is a larger fraction of the host halo mass have more eccentric, radially biased orbits. At fixed satellite-to-host halo mass ratio, high-mass haloes are biased towards accreting satellites on slightly more radial orbits. To characterize the orbital distributions fully requires fitting the correlated bivariate distribution of two chosen orbital parameters (e.g. radial and tangential velocity or energy and angular momentum). We provide simple fits to one choice of the bivariate distributions, which when transformed faithfully, captures the behaviour of any of the projected one-dimensional distributions.
We present distributions of orbital parameters of infalling satellites of ... cold dark matter (...CDM) haloes in the mass range 10...-10... M..., which represent the initial conditions for the ...subsequent evolution of substructures within the host halo. We use merger trees constructed in a high-resolution cosmological N-body simulation to trace satellite haloes, and identify the time of infall. We find significant trends in the distribution of orbital parameters with both the host halo mass and the ratio of satellite-to-host halo masses. For all host halo masses, satellites whose infall mass is a larger fraction of the host halo mass have more eccentric, radially biased orbits. At fixed satellite-to-host halo mass ratio, high-mass haloes are biased towards accreting satellites on slightly more radial orbits. To characterize the orbital distributions fully requires fitting the correlated bivariate distribution of two chosen orbital parameters (e.g. radial and tangential velocity or energy and angular momentum). We provide simple fits to one choice of the bivariate distributions, which when transformed faithfully, captures the behaviour of any of the projected one-dimensional distributions. (ProQuest: ... denotes formulae/symbols omitted.)
We present distributions of orbital parameters of infalling satellites of ... cold dark matter (...CDM) haloes in the mass range 10...-10... M..., which represent the initial conditions for the ...subsequent evolution of substructures within the host halo. We use merger trees constructed in a high-resolution cosmological N-body simulation to trace satellite haloes, and identify the time of infall. We find significant trends in the distribution of orbital parameters with both the host halo mass and the ratio of satellite-to-host halo masses. For all host halo masses, satellites whose infall mass is a larger fraction of the host halo mass have more eccentric, radially biased orbits. At fixed satellite-to-host halo mass ratio, high-mass haloes are biased towards accreting satellites on slightly more radial orbits. To characterize the orbital distributions fully requires fitting the correlated bivariate distribution of two chosen orbital parameters (e.g. radial and tangential velocity or energy and angular momentum). We provide simple fits to one choice of the bivariate distributions, which when transformed faithfully, captures the behaviour of any of the projected one-dimensional distributions. (ProQuest: ... denotes formulae/symbols omitted.)
My research has centred around establishing the nature of dark matter haloes by investigating their abundance as a function of halo mass, the formation his- tory of each halo, commonly called the ...merger tree, and the internal structure of the halo, in terms of their radial density profiles and angular momentum. In the first part of this thesis, I present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as subfind into dark matter haloes whose formation histories are strictly hier- archical. One advantage of these ‘Dhaloes’ over the commonly used friends-of- friends (FoF) haloes is that they retain their individual identity in cases when FoF haloes are artificially merged by tenuous bridges of particles or by an over- lap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi- analytic galaxy formation model, galform. Applying the Dhalo construction to the ΛCDM Millennium-2 simulation we find that approximately 90% of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10% are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF masses. Approximately 80% of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes all three types have similar concentration– M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions. In the second part of this thesis, I present distributions of orbital parameters of infalling satellite haloes at the time of crossing the virial radius of their host halo. Detailed investigation of the orbits is crucial as it represents the initial conditions which determine the later evolution of the substructure within the host. I use merger trees in a high resolution cosmological N-body simulation to trace the satellite haloes and measure their orbits when they first infall into the host halo. I find that there is a trend of the orbital parameters with the ratio between the satellite halo mass and the host halo mass at infall. I find that the more massive satellites move along more eccentric orbits with lower specific angular momentum than less massive satellites. I also search for possible correlations between different orbital parameters and provide accurate fitting formulae for the two independent orbital parameters (the total velocity and the radial-to-total velocity ratio). Using combinations of these formulae, we successfully fit all the other orbital parameters.
My research has centred around establishing the nature of dark matter haloes by investigating their abundance as a function of halo mass, the formation his- tory of each halo, commonly called the ...merger tree, and the internal structure of the halo, in terms of their radial density profiles and angular momentum. In the first part of this thesis, I present a new algorithm which groups the subhaloes found in cosmological N-body simulations by structure finders such as subfind into dark matter haloes whose formation histories are strictly hier- archical. One advantage of these ‘Dhaloes’ over the commonly used friends-of- friends (FoF) haloes is that they retain their individual identity in cases when FoF haloes are artificially merged by tenuous bridges of particles or by an over- lap of their outer diffuse haloes. Dhaloes are thus well suited for modelling galaxy formation and their merger trees form the basis of the Durham semi- analytic galaxy formation model, galform. Applying the Dhalo construction to the ΛCDM Millennium-2 simulation we find that approximately 90% of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10% are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF masses. Approximately 80% of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes all three types have similar concentration– M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions. In the second part of this thesis, I present distributions of orbital parameters of infalling satellite haloes at the time of crossing the virial radius of their host halo. Detailed investigation of the orbits is crucial as it represents the initial conditions which determine the later evolution of the substructure within the host. I use merger trees in a high resolution cosmological N-body simulation to trace the satellite haloes and measure their orbits when they first infall into the host halo. I find that there is a trend of the orbital parameters with the ratio between the satellite halo mass and the host halo mass at infall. I find that the more massive satellites move along more eccentric orbits with lower specific angular momentum than less massive satellites. I also search for possible correlations between different orbital parameters and provide accurate fitting formulae for the two independent orbital parameters (the total velocity and the radial-to-total velocity ratio). Using combinations of these formulae, we successfully fit all the other orbital parameters.
Boundary membranes were recovered from glyoxysomes, transition peroxisomes, and leaf-type peroxisomes purified from cotyledons of sunflower (Helianthus annuus L.) at three stages of postgerminative ...growth. After membranes were washed in 100 mM Na2CO3 (pH 11.5), integral peroxisome membrane proteins (PMPs) were solubilized in buffered aminocaproic acid/dodecyl maltoside (0.63 M/1.5%) and analyzed by nondenaturing and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Six prominent nondenatured PMP complexes and 10 prominent SDS-denatured polypeptides were identified in the membranes of the three types of peroxisomes. A nondenatured complex of approximately 140 kD, composed mainly of 24.5-kD polypeptides, decreased temporally, independently of seedling exposure to white, blue, or red light; only far-red light seemed to prevent its decrease. PMP complexes of approximately 120 and 70 kD, in contrast, were present at all stages and changed in polypeptide contenL It remains to be determined whether these data reflect changes within in vivo complexes or within complexes formed following/during detergent solubilization. Conversion of glyoxysomes to leaf-type peroxisomes in white or red light aher a 2-d dark period was accompanied by the appearance of three SDS-denatured PMPs: 27.5, 28, and 47 kD. The former two became part of the PMP120 and 70 complexes, as well as part of a new PMP130 complex that also possessed the PMP47. Growth of seedlings in blue or far-red light did not promote the appearance of PMPs 27.5 or 28. Blue light promoted the appearance of PMP47, and far-red light seemed to prevent its appearance. Chlorophyll likely is not the photoreceptor involved in accumulation of PMPs because the PMP composition is distinctly different in seedlings irradiated with red or blue light of comparable fluence rates. Several lines of evidence indicate that the synthesis and acquisition of membrane and all matrix proteins are not coupled
We present distributions of orbital parameters of infalling satellites of
$\Lambda$CDM haloes in the mass range $10^{12}-10^{14}$M$_\odot$, which
represent the initial conditions for the subsequent ...evolution of substructures
within the host halo. We use merger trees constructed in a high resolution
cosmological N-body simulation to trace satellite haloes, and identify the time
of infall. We find signficant trends in the distribution of orbital parameters
with both the host halo mass and the ratio of satellite-to-host halo masses.
For all host halo masses, satellites whose infall mass is a larger fraction of
the host halo mass have more eccentric, radially biased orbits. At fixed
satellite-to-host halo mass ratio, high mass haloes are biased towards
accreting satellites on slightly more radial orbits. To charactise the orbital
distributions fully requires fitting the correlated bivariate distribution of
two chosen orbital parameters (e.g. radial and tangential velocity or energy
and angular momentum). We provide simple fits to one choice of the bivariate
distributions, which when transformed faithfully, captures the behaviour of any
of the projected one-dimensional distributions.
We present a new algorithm which groups the subhaloes found in cosmological N- body simulations by structure finders such as SUBFIND into dark matter haloes whose formation histories are strictly ...hierarchical. One advantage of these `Dhaloes' over the commonly used friends-of-friends (FoF) haloes is that they retain their individual identity in cases when FoF haloes are artificially merged by tenuous bridges of particles or by an overlap of their outer diffuse haloes. Dhaloes are thus well-suited for modelling galaxy formation and their merger trees form the basis of the Durham semi-analytic galaxy formation model, GALFORM. Applying the Dhalo construction to the LambdaCDM Millennium-2 simulation we find that approximately 90% of Dhaloes have a one-to-one, bijective match with a corresponding FoF halo. The remaining 10% are typically secondary components of large FoF haloes. Although the mass functions of both types of haloes are similar, the mass of Dhaloes correlates much more tightly with the virial mass, M200, than FoF haloes. Approximately 80% of FoF and bijective and non-bijective Dhaloes are relaxed according to standard criteria. For these relaxed haloes all three types have similar concentration-M200 relations and, at fixed mass, the concentration distributions are described accurately by log-normal distributions.
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