J/ApJ/689/919 Dynamical evolution of globular clusters (Prieto+, 2008)
Dynamical evolution of globular clusters in hierarchical cosmology.
Prieto J.L., Gnedin O.Y.
<Astrophys. J., 689, 919-935 (2008)>
=2008ApJ...689..919P 2008ApJ...689..919P (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Clusters, globular
Keywords: galaxies: formation - galaxies: kinematics and dynamics -
galaxies: star clusters - globular clusters: general
Abstract:
We test the hypothesis that metal-poor globular clusters form within
disk galaxies at redshifts z>3. We calculate the orbits of model
clusters in the time-variable gravitational potential of a Milky
Way-sized galaxy, using the outputs of a cosmological N-body
simulation. We find that at present the orbits are isotropic in the
inner 50kpc of the Galaxy and preferentially radial at larger
distances. All clusters located outside 10kpc from the center formed
in satellite galaxies, some of which are now tidally disrupted and
some of which survive as dwarf galaxies. Mergers of the progenitors
lead to a spheroidal spatial distribution of model clusters, although
it is more extended than that of Galactic metal-poor clusters and has
a somewhat shallower power-law slope of the number density profile,
γ∼2.7. The combination of two-body relaxation, tidal shocks, and
stellar evolution drives the evolution of the cluster mass function
from an initial power law to a peaked distribution, in agreement with
observations. However, not all initial conditions and not all
evolution scenarios are consistent with the observed mass function of
the Galactic globular clusters. We find that our best-fitting models
require the average cluster density, M/R3h, to be constant
initially for clusters of all mass and to remain constant with time.
However, these models do not explain the observed decrease of the mean
density with galactocentric distance. Both synchronous formation of
all clusters at a single epoch (z=4) and continuous formation over a
span of 1.6Gyr (between z=9 and 3) are consistent with the data. For
both formation scenarios, we provide online catalogs of the main
physical properties of model clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 82 97 *Catalog of clusters in model Sb-ii
table4.dat 82 87 *Catalog of clusters in model Cb-ii
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Notes on table3.dat and table4.dat: Models as follows:
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Model Rh(0) Rh(t) γ fM fN logMpeak σ PK-S
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Sb-ii M(0)1/3 M(t)1/3 2.7 0.53 0.46 0.16 5.47 0.52 4E-10
Cb-ii M(0)1/3 M(t)1/3 2.7 0.52 0.15 0.04 5.51 0.71 0.063
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See section 2.3 for further details.
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 --- zf Redshift of formation
5- 8 F4.2 [Msun] logM Present cluster mass
10- 13 F4.2 [Msun] logMi Initial cluster mass
15- 18 F4.1 pc Rh Present half-mass radius
20- 23 F4.1 pc Rhi Initial half-mass radius
25- 29 F5.1 kpc r Present distance to center of main galaxy
31- 35 F5.1 kpc ri Initial distance to center of main galaxy
37- 40 F4.1 [Msun] logMh Host galaxy mass at time of cluster formation
42- 47 F6.1 kpc x x-coordinate of cluster with respect to main galaxy
49- 54 F6.1 kpc y y-coordinate of cluster with respect to main galaxy
56- 61 F6.1 kpc z z-coordinate of cluster with respect to main galaxy
63- 68 F6.1 km/s vx x-velocity of cluster
70- 75 F6.1 km/s vy y-velocity of cluster
77- 82 F6.1 km/s vz z-velocity of cluster
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-Jan-2011