2017A&A...606A..85L


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.03CEST22:03:28

2017A&A...606A..85L - Astronomy and Astrophysics, volume 606A, 85-85 (2017/10-1)

The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type. A tracer of globular cluster formation and evolution.

LAMERS H.J.G.L.M., KRUIJSSEN J.M.D., BASTIAN N., REJKUBA M., HILKER M. and KISSLER-PATIG M.

Abstract (from CDS):

Context. Observations of globular clusters (GCs) and field stars in the halos of the giant elliptical galaxy Cen A and the spiral galaxy M 31 show a large range of cluster-to-star number ratios (or "specific frequencies"). The cluster-to-star ratio decreases with increasing metallicity by over a factor of 100-1000, at all galactocentric radii and with a slope that does not seem to depend on radius. In dwarf galaxies, the GCs are also more metal-poor than the field stars on average. These observations indicate a strong dependence of either the cluster formation efficiency and/or the cluster destruction rate on metallicity and environment.
Aims. We aim to explain the observed trends by considering the various effects that influence the cluster-to-star ratio as a function of metallicity, environment and cosmological history.
Methods. We discuss the following effects that may influence the observed cluster-to-star ratio: (a) the formation efficiency of GCs; (b) the destruction of embedded GCs by gas expulsion; (c) the maximum masses of GCs; (d) the destruction of GCs by tidal stripping, dynamical friction, and tidal shocks as a function of environment; (e) the hierarchical assembly of GC systems during galaxy formation and the dependence on metallicity.
Results. We show that both the cluster formation efficiency and the maximum cluster mass increase with metallicity, so they cannot explain the observed trend. Destruction of GCs by tidal stripping and dynamical friction destroy clusters mostly within the inner few kpc, whereas the cluster-to-star ratio trend is observed over a much larger range of galactocentric radii. We show that cluster destruction by tidal shocks from giant molecular clouds in the high-density formation environments of GCs becomes increasingly efficient towards high galaxy masses and, hence, towards high metallicities. The predicted cluster-to-star ratio decreases by a factor 100-1000 towards high metallicities and should only weakly depend on galactocentric radius due to orbital mixing during hierarchical galaxy merging, consistent with the observations.
Conclusions. The observed, strong dependence of the cluster-to-star ratio on metallicity and the independence of its slope on galactocentric radius can be explained by cluster destruction and hierarchical galaxy growth. During galaxy assembly, GC metallicities remain a good tracer of the host galaxy masses in which the GCs formed and experienced most of their destruction. As a result, we find that the metallicity-dependence of the cluster-to-star ratio does not reflect a GC formation efficiency, but a survival fraction.

Abstract Copyright: © ESO, 2017

Journal keyword(s): globular clusters: general - galaxies: abundances - galaxies: star clusters: general - galaxies: stellar content - galaxies: halos - galaxies: star formation - galaxies: star formation

Simbad objects: 22

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Number of rows : 22

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 32 IG 00 42 41.825 +40 51 54.61 9.51 9.03 8.08     ~ 2009 2
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10902 1
3 NGC 891 H2G 02 22 32.907 +42 20 53.95 11.08 10.81 9.93 7.86   ~ 1520 2
4 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1473 1
5 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5665 1
6 ACO S 373 ClG 03 38 30 -35 27.3           ~ 1538 0
7 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14826 1
8 NGC 2403 AGN 07 36 51.396 +65 36 09.17 9.31 8.84 8.38 8.19   ~ 1606 1
9 NAME M 81-82 Group GrG 09 55 +69.1           ~ 634 0
10 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 3962 5
11 NGC 3115 GiG 10 05 13.978 -07 43 06.89   11   9.37   ~ 926 2
12 NAME IKN G 10 08 05.9 +68 23 57           ~ 61 0
13 NGC 3377 GiP 10 47 42.400 +13 59 08.30 11.55 11.24 10.38     ~ 729 1
14 M 105 LIN 10 47 49.600 +12 34 53.87   10.56 9.76 9.12 8.18 ~ 1379 0
15 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 5824 0
16 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6207 3
17 M 104 LIN 12 39 59.43185 -11 37 22.9954 9.51 9.55 8.00 8.05   ~ 1274 3
18 NAME Cen A Group GrG 13 20 33.9 -44 58 51           ~ 230 0
19 NAME Centaurus A Sy2 13 25 27.61509104 -43 01 08.8056025   8.18 6.84 6.66   ~ 3995 3
20 NGC 5218 GiP 13 32 10.4287653669 +62 46 04.126116981   13.1       ~ 143 1
21 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11533 0
22 NAME Local Group GrG ~ ~           ~ 6970 0

    Equat.    Gal    SGal    Ecl

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2020.07.03-22:03:28

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