J/MNRAS/500/4422 Structural parameters for 99 M82 SSCs (Cuevas-Otahola+, 2021)
Mass-radius relation of intermediate-age disc super star clusters of M82.
Cuevas-Otahola B., Mayya Y.D., Puerari I., Rosa-Gonzalez D.
<Mon. Not. R. Astron. Soc., 500, 4422-4438 (2021)>
=2021MNRAS.500.4422C 2021MNRAS.500.4422C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Models ; Optical
Keywords: catalogues - globular clusters: general
Abstract:
We present a complete set of structural parameters for a sample of 99
intermediate-age super star cluster (SSCs) in the disc of M82, and
carry out a survival analysis using the semi-analytical cluster
evolution code EMACSS. The parameters are based on the profile-fitting
analysis carried out in previous work, with the mass-related
quantities derived using a mass-to-light ratio for a constant age of
100Myr. The SSCs follow a power-law mass function with an index
α=1.5, and a lognormal size function with a typical half-light
radius, Rh=4.3pc, which is both comparable with the values for
clusters in the Magellanic Clouds, rather than in giant spirals. The
majority of the SSCs follow a power-law mass-radius relation with an
index of b=0.29±0.05. A dynamical analysis of M82 SSCs using EMACSS
suggests that 23 per cent of the clusters are tidally limited, with
the rest undergoing expansion at present. Forward evolution of these
clusters suggests that the majority would dissolve in ∼2Gyr. However,
a group of four massive compact clusters, and another group of five
SSCs at relatively large galactocentric distances, are found to
survive for a Hubble time. The model-predicted mass, Rh, µV,
and core radius of these surviving SSCs at 12Gyr are comparable with
the corresponding values for the sample of Galactic globular clusters.
Description:
In this work, we analyse the mass-radius relation for the M82 disc
SSCs sample studied in Paper I. The sample consists of 99 SSCs from
the M82 disc SSCs sample of 393 clusters from Mayya et al.
(2008ApJ...679..404M 2008ApJ...679..404M, Cat. J/ApJ/679/404), selected on the archival
images of the HST Legacy Survey (Mutchler et al. 2007PASP..119....1M 2007PASP..119....1M).
In Paper I, we have demonstrated that the sub-sample of 99 SSCs
represents the bright end of the total sample. The structural
parameters were derived for the best-fitting Moffat-EFF (Elson, Fall &
Freeman 1987ApJ...323...54E 1987ApJ...323...54E), King (1966AJ.....71...64K 1966AJ.....71...64K), and Wilson
(1975AJ.....80..175W 1975AJ.....80..175W) models. We found that the Moffat-EFF model is
the best fit for 95 per cent of the cases, and hence in this study we
use the parameters of this model.
In Paper I, we presented the results for the core radius Rc and the
power-law index γ for the disc sample. In this paper, we use the
results of the profile fitting to calculate the full set of structural
parameters that includes half-light radius Rh, central mass density
(logρ0), central surface density (logΣ0), central
velocity dispersion, luminosity, and mass. We include also an
important quantity related to the initial conditions of the cluster
with respect to the galaxy tidal field, i.e. the initial half-mass to
Jacobi radius ratio. In Table 1, we summarize all the derived
parameters in the V band for the Moffat-EFF model for all the
clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 188 99 Moffat-EFF model-derived parameters
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See also:
J/MNRAS/492/993 : Super star clusters of M82's disk
J/ApJ/679/404 : Star clusters in M82 (Mayya+, 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- ID Cluster identifier (DNNN) as in
Cuevas-Otahola et al.
(2020MNRAS.492..993C 2020MNRAS.492..993C,
Cat. J/MNRAS/492/993)
6- 9 F4.2 kpc Rg Galactocentric radius
11- 14 F4.2 pc gamma Moffat-EFF power-law index (1)
16- 19 F4.2 pc e_gamma Lower error on gamma
21- 24 F4.2 pc E_gamma Upper error on gamma
26- 29 F4.2 pc Rc Core radius (2)
31- 34 F4.2 pc e_Rc Lower error on Rc
36- 39 F4.2 pc E_Rc Upper error on Rc
41- 45 F5.2 pc Rh Half-light radius (3)
47- 50 F4.2 pc e_Rh Lower error on Rh
52- 55 F4.2 pc E_Rh Upper error on Rh
57- 61 F5.2 pc Rt Tidal radius
63- 66 F4.2 pc e_Rt Lower error on Rt
68- 71 F4.2 pc E_Rt Upper error on Rt
73- 76 F4.2 --- Mb/M Fraction of the total mass of Moffat-EFF
profile within the tidal radius (4)
78- 81 F4.2 [Msun/pc3] logrho0 Logarithm of central mass volume density
(5)
83- 86 F4.2 [Msun/pc3] e_logrho0 Lower error on logrho0
88- 91 F4.2 [Msun/pc3] E_logrho0 Upper error on logrho0
93- 96 F4.2 [Msun/pc2] logSig0 Logarithm of central mass surface density
(5)
98- 101 F4.2 [Msun/pc2] e_logSig0 Lower error on logSig0
103- 106 F4.2 [Msun/pc2] E_logSig0 Upper error on logSig0
108- 111 F4.2 [Msun] logM Logarithm of total mass (5)
113- 116 F4.2 [Msun] e_logM Lower error on logM
118- 121 F4.2 [Msun] E_logM Upper error on logM
123- 126 F4.2 [Lsun] logLtot Logarithm of total luminosity
128- 131 F4.2 [Lsun] e_logLtot Lower error on logLtot
133- 136 F4.2 [Lsun] E_logLtot Upper error on logLtot
138- 142 F5.2 [Msun/pc3] logrhoh Logarithm of half-light mass volume
density (5)
144- 147 F4.2 [Msun/pc3] e_logrhoh Lower error on logrhoh
149- 152 F4.2 [Msun/pc3] E_logrhoh Upper error on logrhoh
154- 157 F4.2 [Lsun/pc2] logIh Logarithm of average surface brightness
within Rh
159- 162 F4.2 [Lsun/pc2] e_logIh Lower error on logIh
164- 167 F4.2 [Lsun/pc2] E_logIh Upper error on logIh
169- 173 F5.2 km/s sigmap Projected central velocity dispersion
σp (5)
175- 178 F4.2 km/s e_sigmap Lower error on sigmap
180- 183 F4.2 km/s E_sigmap Upper error on sigmap
185- 188 F4.2 --- Rh/Rj Initial half-mass to Jacobi radius ratio
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Note (1): Moffat-EFF power-law index from Cuevas-Otahola et al.
(2020MNRAS.492..993C 2020MNRAS.492..993C, Cat. J/MNRAS/492/993) (Paper I) except that
γ>4 are set to 4
Note (2): The core radius is calculated using equation 2 of the article:
rd=Rc/sqrt(22/γ-1), where rd is the characteristic
radius
Note (3): The half-light radius is analytically related to the fitted
structural parameters rd and γ by:
Rh=rdsqrt(0.51/(1-γ/2)-1)
Note (4): From the obtained Rt values it is possible to compute the bound
mass of the cluster Mbound, by integrating Σ(R) in the limits
between 0 and Rt. This integration has an analytical solution given
by Elson et al. (1987ApJ...323...54E 1987ApJ...323...54E):
Mbound/M=1-[1+(Rt/rd)2](1-γ/2)
Note (5): The mass-related quantities are obtained from the corresponding
luminosity-related quantities assuming a mass-to-light ratio for a
simple stellar population model (SSP) of 100Myr and using a Kroupa
IMF (Kroupa 2001MNRAS.322..231K 2001MNRAS.322..231K). The effects of a different age
choice are given by adding the term 0.57log(t/100Myr) and for
σp by multiplying by sqrt((t/100Myr)0.57).
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History:
From electronic version of the journal
References:
Cuevas-Otahola et al., Paper I 2020MNRAS.492..993C 2020MNRAS.492..993C, Cat. J/MNRAS/492/993
(End) Ana Fiallos [CDS] 11-Oct-2023