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E K Grebel - One of the best experts on this subject based on the ideXlab platform.
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on the origin of the radial Mass Density profile of the galactic halo globular cluster system
Monthly Notices of the Royal Astronomical Society, 2005Co-Authors: Genevieve Parmentier, E K GrebelAbstract:We investigate what may be the origin of the presently observed spatial distribution of the Mass of the Galactic Old Halo globular cluster system. We propose its radial Mass Density profile to be a relic of the distribution of the cold baryonic material in the protogalaxy. Assuming that this one arises from the profile of the whole protogalaxy minus the contribution of the dark matter (and a small contribution of the hot gas by which the protoglobular clouds were bound), we show that the Mass distributions around the Galactic centre of this cold gas and of the Old Halo agree satisfactorily. In order to demonstrate our hypothesis even more conclusively, we simulate the evolution with time, up to an age of 15 Gyr, of a putative globular cluster system whose initial Mass distribution in the Galactic halo follows the profile of the cold protogalactic gas. We show that beyond a galactocentric distance of order 2-3 kpc, the initial shape of such a Mass Density profile is preserved despite the complete destruction of some globular clusters and the partial evaporation of some others. This result is almost independent of the choice of the initial Mass function for the globular clusters, which is still ill determined. The shape of these evolved cluster system Mass Density profiles also agrees with the presently observed profile of the Old Halo globular cluster system, thus strengthening our hypothesis. Our result might suggest that the flattening shown by the Old Halo Mass Density profile at short distances from the Galactic centre is, at least partly, of primordial origin.
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on the origin of the radial Mass Density profile of the galactic halo globular cluster system
arXiv: Astrophysics, 2005Co-Authors: Genevieve Parmentier, E K GrebelAbstract:We investigate what may be the origin of the presently observed spatial distribution of the Mass of the Galactic Old Halo globular cluster system. We propose its radial Mass Density profile to be a relic of the distribution of the cold baryonic material in the protoGalaxy. Assuming that this one arises from the profile of the whole protoGalaxy minus the contribution of the dark matter (and a small contribution of the hot gas by which the protoglobular clouds were bound), we show that the Mass distributions around the Galactic centre of this cold gas and of the Old Halo agree satisfactorily. In order to demonstrate our hypothesis even more conclusively, we simulate the evolution with time, up to an age of 15 Gyr, of a putative globular cluster system whose initial Mass distribution in the Galactic halo follows the profile of the cold protogalactic gas. We show that beyond a galactocentric distance of order 2 to 3 kpc, the initial shape of such a Mass Density profile is preserved in spite of the complete destruction of some globular clusters and the partial evaporation of some others. This result is almost independent of the choice of the initial Mass function for the globular clusters, which is still ill-determined. The shape of these evolved cluster system Mass Density profiles also agree with the presently observed profile of the Old Halo globular cluster system, thus strengthening our hypothesis. Our result might suggest that the flattening shown by the Old Halo Mass Density profile at short distance from the Galactic centre is, at least partly, of primordial origin.
F J De Cos Juez - One of the best experts on this subject based on the ideXlab platform.
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qsos sigposting cluster size halos as gravitational lenses halo Mass projected Mass Density profile and concentration at z 0 7
Journal of Cosmology and Astroparticle Physics, 2019Co-Authors: L Bonavera, J Gonzaleznuevo, Sergio Luis Suarez Gomez, A Lapi, F Bianchini, M Negrello, Diez E Alonso, J D Santos, F J De Cos JuezAbstract:Magnification bias is a gravitational lensing effect that is normally overlooked because it is considered sub-optimal in comparison with the lensing shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre galaxies (SMGs) for lensing analysis, in this work we were able to measure the magnification bias produced by a sample of QSOs acting as lenses, 0.2 13.6−0.4+0.9, also confirmed by the Mass Density profile analysis (M200c~ 1014 M⊙). These Mass values indicate that we are observing the lensing effect of a cluster size halo signposted by the QSOs, as in previous studies of the magnification bias. Moreover, we were able to estimate the lensing convergence, κ(θ), for our magnification bias measurements down to a few kpcs. The derived Mass Density profile is in good agreement with a Navarro-Frank-White (NFW) profile. We also attempt an estimation of the halo Mass and the concentration parameters, obtaining MNFW=1.0+0.4−0.2×1014 M⊙ and C=3.5−0.3+0.5. This concentration value is rather low and it would indicate that the cluster halos around these QSOs are unrelaxed. However, higher concentration values still provides a compatible fit to the data.
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qsos sigposting cluster size halos as gravitational lenses halo Mass projected Mass Density profile and concentration at z sim0 7
arXiv: Cosmology and Nongalactic Astrophysics, 2019Co-Authors: L Bonavera, J Gonzaleznuevo, Sergio Luis Suarez Gomez, A Lapi, F Bianchini, M Negrello, Diez E Alonso, J D Santos, F J De Cos JuezAbstract:Magnification bias is a gravitational lensing effect that is normally overlooked because it is considered sub-optimal in comparison with the lensing shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre galaxies (SMGs) for lensing analysis, in this work we were able to measure the magnification bias produced by a sample of QSOs acting as lenses, $0.2 13.6_{-0.4}^{+0.9}$, also confirmed by the Mass Density profile analysis ($M_{200c}\sim 10^{14} M_\odot$). These Mass values indicate that we are observing the lensing effect of a cluster size halo signposted by the QSOs, as in previous studies of the magnification bias. Moreover, we were able to estimate the lensing convergence, $\kappa(\theta)$, for our magnification bias measurements down to a few kpcs. The derived Mass Density profile is in good agreement with a Navarro-Frank-White (NFW) profile. We also attempt an estimation of the halo Mass and the concentration parameters, obtaining $M_{NFW}=1.0^{+0.4}_{-0.2}\times10^{14} M_\odot$ and $C=3.5_{-0.3}^{+0.5}$. This concentration value is rather low and it would indicate that the cluster halos around these QSOs are unrelaxed. However, higher concentration values still provides a compatible fit to the data.
A Lapi - One of the best experts on this subject based on the ideXlab platform.
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qsos sigposting cluster size halos as gravitational lenses halo Mass projected Mass Density profile and concentration at z 0 7
Journal of Cosmology and Astroparticle Physics, 2019Co-Authors: L Bonavera, J Gonzaleznuevo, Sergio Luis Suarez Gomez, A Lapi, F Bianchini, M Negrello, Diez E Alonso, J D Santos, F J De Cos JuezAbstract:Magnification bias is a gravitational lensing effect that is normally overlooked because it is considered sub-optimal in comparison with the lensing shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre galaxies (SMGs) for lensing analysis, in this work we were able to measure the magnification bias produced by a sample of QSOs acting as lenses, 0.2 13.6−0.4+0.9, also confirmed by the Mass Density profile analysis (M200c~ 1014 M⊙). These Mass values indicate that we are observing the lensing effect of a cluster size halo signposted by the QSOs, as in previous studies of the magnification bias. Moreover, we were able to estimate the lensing convergence, κ(θ), for our magnification bias measurements down to a few kpcs. The derived Mass Density profile is in good agreement with a Navarro-Frank-White (NFW) profile. We also attempt an estimation of the halo Mass and the concentration parameters, obtaining MNFW=1.0+0.4−0.2×1014 M⊙ and C=3.5−0.3+0.5. This concentration value is rather low and it would indicate that the cluster halos around these QSOs are unrelaxed. However, higher concentration values still provides a compatible fit to the data.
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qsos sigposting cluster size halos as gravitational lenses halo Mass projected Mass Density profile and concentration at z sim0 7
arXiv: Cosmology and Nongalactic Astrophysics, 2019Co-Authors: L Bonavera, J Gonzaleznuevo, Sergio Luis Suarez Gomez, A Lapi, F Bianchini, M Negrello, Diez E Alonso, J D Santos, F J De Cos JuezAbstract:Magnification bias is a gravitational lensing effect that is normally overlooked because it is considered sub-optimal in comparison with the lensing shear. Thanks to the demonstrated optimal characteristics of the sub-millimetre galaxies (SMGs) for lensing analysis, in this work we were able to measure the magnification bias produced by a sample of QSOs acting as lenses, $0.2 13.6_{-0.4}^{+0.9}$, also confirmed by the Mass Density profile analysis ($M_{200c}\sim 10^{14} M_\odot$). These Mass values indicate that we are observing the lensing effect of a cluster size halo signposted by the QSOs, as in previous studies of the magnification bias. Moreover, we were able to estimate the lensing convergence, $\kappa(\theta)$, for our magnification bias measurements down to a few kpcs. The derived Mass Density profile is in good agreement with a Navarro-Frank-White (NFW) profile. We also attempt an estimation of the halo Mass and the concentration parameters, obtaining $M_{NFW}=1.0^{+0.4}_{-0.2}\times10^{14} M_\odot$ and $C=3.5_{-0.3}^{+0.5}$. This concentration value is rather low and it would indicate that the cluster halos around these QSOs are unrelaxed. However, higher concentration values still provides a compatible fit to the data.
Genevieve Parmentier - One of the best experts on this subject based on the ideXlab platform.
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on the origin of the radial Mass Density profile of the galactic halo globular cluster system
Monthly Notices of the Royal Astronomical Society, 2005Co-Authors: Genevieve Parmentier, E K GrebelAbstract:We investigate what may be the origin of the presently observed spatial distribution of the Mass of the Galactic Old Halo globular cluster system. We propose its radial Mass Density profile to be a relic of the distribution of the cold baryonic material in the protogalaxy. Assuming that this one arises from the profile of the whole protogalaxy minus the contribution of the dark matter (and a small contribution of the hot gas by which the protoglobular clouds were bound), we show that the Mass distributions around the Galactic centre of this cold gas and of the Old Halo agree satisfactorily. In order to demonstrate our hypothesis even more conclusively, we simulate the evolution with time, up to an age of 15 Gyr, of a putative globular cluster system whose initial Mass distribution in the Galactic halo follows the profile of the cold protogalactic gas. We show that beyond a galactocentric distance of order 2-3 kpc, the initial shape of such a Mass Density profile is preserved despite the complete destruction of some globular clusters and the partial evaporation of some others. This result is almost independent of the choice of the initial Mass function for the globular clusters, which is still ill determined. The shape of these evolved cluster system Mass Density profiles also agrees with the presently observed profile of the Old Halo globular cluster system, thus strengthening our hypothesis. Our result might suggest that the flattening shown by the Old Halo Mass Density profile at short distances from the Galactic centre is, at least partly, of primordial origin.
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on the origin of the radial Mass Density profile of the galactic halo globular cluster system
arXiv: Astrophysics, 2005Co-Authors: Genevieve Parmentier, E K GrebelAbstract:We investigate what may be the origin of the presently observed spatial distribution of the Mass of the Galactic Old Halo globular cluster system. We propose its radial Mass Density profile to be a relic of the distribution of the cold baryonic material in the protoGalaxy. Assuming that this one arises from the profile of the whole protoGalaxy minus the contribution of the dark matter (and a small contribution of the hot gas by which the protoglobular clouds were bound), we show that the Mass distributions around the Galactic centre of this cold gas and of the Old Halo agree satisfactorily. In order to demonstrate our hypothesis even more conclusively, we simulate the evolution with time, up to an age of 15 Gyr, of a putative globular cluster system whose initial Mass distribution in the Galactic halo follows the profile of the cold protogalactic gas. We show that beyond a galactocentric distance of order 2 to 3 kpc, the initial shape of such a Mass Density profile is preserved in spite of the complete destruction of some globular clusters and the partial evaporation of some others. This result is almost independent of the choice of the initial Mass function for the globular clusters, which is still ill-determined. The shape of these evolved cluster system Mass Density profiles also agree with the presently observed profile of the Old Halo globular cluster system, thus strengthening our hypothesis. Our result might suggest that the flattening shown by the Old Halo Mass Density profile at short distance from the Galactic centre is, at least partly, of primordial origin.
S B Pope - One of the best experts on this subject based on the ideXlab platform.
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frequency velocity scalar filtered Mass Density function for large eddy simulation of turbulent flows
Physics of Fluids, 2009Co-Authors: M R H Sheikhi, Peyman Givi, S B PopeAbstract:A methodology termed “frequency-velocity-scalar filtered Mass Density function” (FVS-FMDF) is developed for large eddy simulation (LES) of turbulent flows. The FVS-FMDF takes account of unresolved subgrid scales (SGSs) by considering the joint probability Density function (PDF) of the frequency, the velocity, and the scalar fields. An exact transport equation is derived for the FVS-FMDF in which the effects of convection and chemical reaction are in closed forms. The unclosed terms in this equation are modeled in a fashion similar to PDF methods in Reynolds-averaged Navier–Stokes simulations. The FVS-FMDF transport is modeled via a set of stochastic differential equations (SDEs). The numerical solution procedure is based on a hybrid finite-difference (FD)/Monte Carlo (MC) method in which the LES filtered transport equations are solved by the FD, and the set of SDEs is solved by a Lagrangian MC procedure. LES of a temporally developing mixing layer is conducted via the FVS-FMDF, and the results are compare...
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velocity scalar filtered Mass Density function for large eddy simulation of turbulent reacting flows
Physics of Fluids, 2007Co-Authors: M R H Sheikhi, Peyman Givi, S B PopeAbstract:A methodology termed the “velocity-scalar filtered Mass Density function” (VSFMDF) is developed and implemented for large eddy simulation (LES) of variable-Density turbulent reacting flows. This methodology is based on the extension of the previously developed “velocity-scalar filtered Density function” method for constant-Density flows. In the VSFMDF, the effects of the unresolved subgrid scales (SGS) are taken into account by considering the joint probability Density function of the velocity and scalar fields. An exact transport equation is derived for the VSFMDF in which the effects of SGS convection and chemical reaction are in closed forms. The unclosed terms in this equation are modeled in a fashion similar to that in Reynolds-averaged simulation procedures. A set of stochastic differential equations (SDEs) are considered which yield statistically equivalent results to the modeled VSFMDF transport equation. The SDEs are solved numerically by a Lagrangian Monte Carlo procedure in which the Ito-Gikhma...
