The ACS Virgo Cluster Survey. X. Half-Light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation

By A. Jord'an, P. Côté, J. Blakeslee, L. Ferrarese, D. McLaughlin, S. Mei, E. Peng, J. Tonry, D. Merritt, Milos Milosavljevic and 3 more. 2005

224 citations recorded by the source corpus.

We have measured half-light radii, rh, for thousands of globular clusters (GCs) belonging to the 100 early-type galaxies observed in the ACS Virgo Cluster Survey and the elliptical galaxy NGC 4697. An analysis of the dependencies of the measured half-light radii on both the properties of the GCs themselves and their host galaxies reveals that, in analogy with GCs in the Galaxy but in a milder fashion, the average half-light radius increases with increasing galactocentric distance or, alternatively, with decreasing galaxy surface brightness. For the first time, we find that the average half-light radius decreases with the host galaxy color. We also show that there is no evidence for a variation of rh with the luminosity of the GCs. Finally, we find in agreement with previous observations that the average rh depends on the color of GCs, with red GCs being ~17% smaller than their blue counterparts. We show that this difference is probably a consequence of an intrinsic mechanism, rather than projection effects, and that it is in good agreement with the mechanism proposed by Jordán. We discuss these findings in light of two simple pictures for the origin of the rh of GCs and show that both lead to a behavior in rough agreement with the observations. After accounting for the dependencies on galaxy color, galactocentric radius, and underlying surface brightness, we show that the average GC half-light radii ⟨rh⟩ can be successfully used as a standard ruler for distance estimation. We outline the methodology, provide a calibration for its use, and discuss the prospects for this distance estimator with future observing facilities. We find ⟨rh⟩ = 2.7 ± 0.35 pc for GCs with (g - z) = 1.2 mag in a galaxy with color (g - z)gal = 1.5 mag and at an underlying surface z-band brightness of μz = 21 mag arcsec-2. Using this technique, we place an upper limit of 3.4 Mpc on the 1 σ line-of-sight depth of the Virgo Cluster. Finally, we examine the form of the rh distribution for our sample galaxies and provide an analytic expression that successfully describes this distribution.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/5d248ab83d9f56f407341e2ed094e3336ac5c0a7

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In Astronomy and Astrophysics

1. D. Merritt
2. Alister W. Graham
3. P. Hopkins
4. J. Strader
5. J. Brodie
6. Luis C. Ho
7. L. Ferrarese
8. J. Kormendy

In Instrumentation

1. J. Strader
2. J. Brodie
3. L. Ferrarese
4. E. Peng
5. P. Côté
6. D. Merritt
7. S. Mei
8. J. Blakeslee

Citations in the corpus

• THE ACS FORNAX CLUSTER SURVEY. V. MEASUREMENT AND RECALIBRATION OF SURFACE BRIGHTNESS FLUCTUATIONS AND A PRECISE VALUE OF THE FORNAX–VIRGO RELATIVE DISTANCE (2009, methodology): “The NGC 4697 observational details were identical to those of the ACSVCS galaxies and have been discussed by Jordán et al. (2005).”
• GALAXIES AT THE EXTREMES: ULTRA-DIFFUSE GALAXIES IN THE VIRGO CLUSTER (2015, methodology): “VLSB-A’s nucleus is marginally resolved in our NGVS imaging; a structural analysis of the nucleus using KINGPHOT (Jordán et al. 2005, Liu et al. 2015) yields an effective radius of re,g = 0.27 ′′ (22 pc).”
• Extragalactic Globular Clusters and Galaxy Formation (2006, background): “Jordán et al. (2005) studied GC sizes in 67 early-type galaxies with a wide range of luminosity from the ACS Virgo Cluster Survey (Côté et al. 2004).”
• The ACS Virgo Cluster Survey. XIII. SBF Distance Catalog and the Three-dimensional Structure of the Virgo Cluster (2007, methodology): “…color distributions of globular clusters (Peng et al. 2006a = Paper IX), the half light radii of globular clusters and their use as a distance indicator (Jordán et al. 2005a = Paper X), diffuse star clusters in early-type galaxies (Peng et al. 2006b = Paper XI) and the connection between…”
• The life cycle of star clusters in a tidal field (2011, methodology): “…established correlations between structural parameters and their environment as found for Milky Way globular clusters (e.g. Djorgovski 1995; McLaughlin 2000) and for extra-galactic globular cluster systems (e.g. Jordán et al. 2005; Barmby et al. 2007; McLaughlin et al. 2008; Harris et al. 2010).”
• DISSIPATIONLESS FORMATION AND EVOLUTION OF THE MILKY WAY NUCLEAR STAR CLUSTER (2011, background): “The typical half-mass radius of a globular cluster is about 3 pc (Jordán et al. 2005) so for a nucleus assembled from 25 mergers, R ∼ 15 pc.”
• THE NEXT GENERATION VIRGO CLUSTER SURVEY (NGVS). I. INTRODUCTION TO THE SURVEY (2012, unknown): “…to these galaxies was used to examine their basic properties in relation to those of their host galaxies (e.g., Peng et al. 2006a, 2006b, 2008; Mieske et al. 2006, 2010; Jordán et al. 2004, 2005, 2007, 2009; Sivakoff et al. 2007; Villegas et al. 2010; Masters et al. 2010; Liu et al. 2011).”
• THE ACS VIRGO CLUSTER SURVEY XVI. SELECTION PROCEDURE AND CATALOGS OF GLOBULAR CLUSTER CANDIDATES (2008, methodology): “…galaxies (Côté et al. 2006), the color distribution of GCs (Peng et al. 2006a), the half-light radii of GCs and their use as a distance indicator (Jordán et al. 2005), diffuse star clusters in early-type galaxies (Peng et al. 2006b), the connection between supermassive black holes and…”
• The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early-Type Galaxies (2007, methodology): “Columns (12)–(21) are the correspondingz- andg-band data for an alternate GC sample defined strictly by magnitude cuts and an upper limit of Rh < 0:00064’ 5 pc (which will include the large majority of real GCs; Jordán et al. 2005), rather than by relying on our pGC probabilities.”
• HyperLEDA. III. The catalogue of extragalactic distances (2014, methodology): “GCR: The median of the globular cluster half-light radii (GCR) of 2.7± 0.3 pc (Jordán et al. 2005, for example) can be used as a standard ruler for the distance estimate.”
• THE RELATIONSHIPS AMONG COMPACT STELLAR SYSTEMS: A FRESH VIEW OF ULTRACOMPACT DWARFS (2011, methodology): “Following Baumgardt et al. (2010), the predicted rt, or Jacobi radius (which is not necessarily the same as the 5 Jordán et al. (2005) and Masters et al. (2010) found α near zero for GCs in a large sample of early-type galaxies in Virgo and Fornax, including M87.”
• From star clusters to dwarf galaxies: the properties of dynamically hot stellar systems (2008, background): “Nevertheless, this seems to be the case to some extent, as surveys of extragalactic GC systems show (e.g. Larsen et al. 2001; Chandar et al. 2004 and Jordán et al. 2005 concerning the radii of GCs, and Richtler 2003 and Jordán et al. 2007 concerning the absolute magnitudes of GCs, which indicate…”
• THE STRUCTURE OF THE M87 JET: A TRANSITION FROM PARABOLIC TO CONICAL STREAMLINES (2011, background): “INTRODUCTION M 87 is one of the nearest active galaxies (16.7 Mpc; Jordán et al. 2005) which exhibits relativistic outflows.”
• The SLUGGS Survey: kinematics for over 2500 globular clusters in 12 early-type galaxies (2012, background): “For instance, the two GC subpopulations are found to have different physical sizes (Kundu & Whitmore 2001; Jordán et al. 2005; Masters et al. 2010) and diverse spatial distributions around the host galaxy, with the metal-rich (red) GCs more centrally concentrated than the metal-poor (blue) GCs…”
• WIDE-FIELD PRECISION KINEMATICS OF THE M87 GLOBULAR CLUSTER SYSTEM (2011, background): “Considering the Jordán et al. (2009) sizes themselves: there are measurements in two different bands (F475W and F850LP), with a systematic difference of ∼ 0.25 pc between the filters (F850LP sizes are larger; Jordán et al. 2005).”