Distance to the Coma Cluster and a Value for HO Inferred from Globular Clusters in IC 4051

Baum, W. A.; Hammergren, M.; Thomsen, B.; Groth, Edward J.; Faber, S. M.; Grillmair, Carl J.; Ajhar, Edward A.

doi:10.1086/118365

Cited by 29 publications

(35 citation statements)

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“…In Papers I and II of our series on the Coma cluster (Kavelaars et al 2000;Harris et al 2000), we discussed the GCS in NGC 4874, the supergiant cD-type elliptical that lies near the center of the larger Coma potential well. In Baum et al (1997) and in our Paper III (Woodworth & Harris 2000), similar material was presented for IC 4051, another giant on the outskirts of the Coma cluster core region. In the present paper, we discuss new results (GCS radial distribution, total population, metallicity distribution, and luminosity function) for two additional Coma members, NGC 4889 and 4926, that have not previously been published.…”

Section: Introductionsupporting

confidence: 68%

The Globular Cluster Systems in the Coma Ellipticals. Iv: Wfpc2 Photometry for Five Giant Ellipticals ,

Harris

Kavelaars

Hanes

et al. 2009

The Astronomical Journal

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We analyze photometric data in V and I for the globular cluster (GC) systems in five of the giant ellipticals in the Coma Cluster: NGC 4874, 4881, 4889, 4926, and IC 4051. All of the raw data, from the Hubble Space Telescope WFPC2 Archive, are analyzed in a homogeneous way so that their five cluster systems can be strictly intercompared. We find that the GC luminosity functions are quite similar to one another and reinforce the common nature of the mass distribution of old, massive star clusters in gE galaxies. The GCLF turnover derived from a composite sample of more than 9, 000 GCs appears at V = 27.71 ± 0.07 (M V = −7.3), and our data reach about half a magnitude fainter Institute, which is operated by the Association

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Section: Introductionsupporting

confidence: 68%

The Globular Cluster Systems in the Coma Ellipticals. Iv: Wfpc2 Photometry for Five Giant Ellipticals ,

Harris

Kavelaars

Hanes

et al. 2009

The Astronomical Journal

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“…This was implicit in the work of McLaughlin (1994), who advocated using piecewise power laws to fit the number of GCs per unit linear luminosity-or piecewise exponentials to describe the usual number of GCs per unit magnitude. Baum et al (1997) used an asymmetric hyperbolic function to fit the strong peak and asymmetry in the combined Galactic and M31 GCLF.…”

Section: The Standard Modelmentioning

confidence: 99%

The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early‐Type Galaxies

Jordán

McLaughlin

Côté

et al. 2007

ASTROPHYS J SUPPL S

320

357

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We analyze the luminosity function of the globular clusters (GCs) belonging to the early-type galaxies observed in the ACS Virgo Cluster Survey. We have obtained maximum likelihood estimates for a Gaussian representation of the globular cluster luminosity function (GCLF) for 89 galaxies. We have also fit the luminosity functions with an "evolved Schechter function", which is meant to reflect the preferential depletion of low-mass GCs, primarily by evaporation due to two-body relaxation, from an initial Schechter mass function similar to that of young massive clusters in local starbursts and mergers. We find a highly significant trend of the GCLF dispersion σ with galaxy luminosity, in the sense that the GC systems in smaller galaxies have narrower luminosity functions. The GCLF dispersions of our Galaxy and M31 are quantitatively in keeping with this trend, and thus the correlation between σ and galaxy luminosity would seem more fundamental than older notions that the GCLF dispersion depends on Hubble type. We show that this narrowing of the GCLF in a Gaussian description is driven by a steepening of the cluster mass function above the classic turnover mass, as one moves to lower-luminosity host galaxies. In a Schechter-function description, this is reflected by a steady decrease in the value of the exponential cut-off mass scale. We argue that this behavior at the high-mass end of the GC mass function is most likely a consequence of systematic variations of the initial cluster mass function rather than long-term dynamical evolution. The GCLF turnover mass M TO is roughly constant, at M TO ≃ (2.2 ± 0.4) × 10 5 M ⊙ in bright galaxies, but it decreases slightly (by ∼ 35% on average, with significant scatter) in dwarf galaxies with M B,gal −18. It could be important to allow for this effect when using the GCLF as a distance indicator. We show that part, though perhaps not all, of the variation could arise from the shorter dynamical friction timescales in less massive galaxies. We probe the variation of the GCLF to projected galactocentric radii of 20-35 kpc in the Virgo giants M49 and M87, finding that the turnover point is essentially constant over these spatial scales. Our fits of evolved Schechter functions imply average dynamical mass losses (∆) over a Hubble time that vary more than M TO , and systematically but non-monotonically as a function of galaxy luminosity. If the initial GC mass distributions rose steeply towards low masses as we assume, then these losses fall in the range 2 × 10 5 M ⊙ ∆ < 10 6 M ⊙ per GC for all of our galaxies. The trends in ∆ are broadly consistent with observed, small variations of the mean GC half-light radius in ACSVCS galaxies, and with rough estimates of the expected scaling of average evaporation rates (galaxy densities) versus total luminosity. We agree with previous suggestions that if the full GCLF is to be understood in more detail, especially alongside other properties of GC systems, the next generation of GCLF models will have to include self-consistent treatments of dyn...

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“…The sample chosen for this present, higher‐resolution spectroscopic study was selected to include only spectroscopically confirmed members of the Coma cluster and to have 14.5 < R Kron < 19.4 and 19.5 < 〈μ R 〉 < 24.3 mag arcsec −2 , where R Kron and 〈μ〉 are the Kron magnitudes and average surface brightness over the Kron radius (an intensity weighted radius; Mob01), respectively. These limits correspond to −20.6 < M R < −15.7, and thus our sample includes galaxies on either side of the boundary between dwarfs and giants, which we define following Mob01 to be at M R =−17.5 or R = 17.6 at the distance of Coma, assuming a distance modulus of 35.1 for the cluster (Baum et al 1997). For simplicity, we will primarily refer to these objects as dwarfs, given that the sample as a whole covers a distinct region of parameter space in luminosity and velocity dispersion compared to previous studies.…”

Section: Observationsmentioning

confidence: 99%

Velocity dispersion measurements of dwarf galaxies in the Coma cluster - implications for the structure of the fundamental plane

Cody

Carter

Bridges

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We present intermediate‐resolution spectroscopic data for a set of dwarf and giant galaxies in the Coma cluster, with −20.6 < MR < −15.7. The photometric and kinematic properties of the brighter galaxies can be cast in terms of parameters which present little scatter with respect to a set of scaling relations known as the fundamental plane. To determine the form of these fundamental scaling relations at lower luminosities, we have measured velocity dispersions for a sample comprising 69 galaxies on the border of the dwarf and giant regime. Combining these data with our photometric survey, we find a tight correlation of luminosity and velocity dispersion, L∝σ2.0, substantially flatter than the Faber–Jackson relation characterizing giant elliptical galaxies. In addition, the variation of mass‐to‐light (M/L) ratio with velocity dispersion is quite weak in our dwarf sample: M/L∝σ0.2. Our overall results are consistent with theoretical models invoking large‐scale mass removal and subsequent structural readjustment, e.g. as a result of galactic winds.

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Distance to the Coma Cluster and a Value for HO Inferred from Globular Clusters in IC 4051

Cited by 29 publications

References 0 publications

The Globular Cluster Systems in the Coma Ellipticals. Iv: Wfpc2 Photometry for Five Giant Ellipticals ,

The Globular Cluster Systems in the Coma Ellipticals. Iv: Wfpc2 Photometry for Five Giant Ellipticals ,

The ACS Virgo Cluster Survey. XII. The Luminosity Function of Globular Clusters in Early‐Type Galaxies

Velocity dispersion measurements of dwarf galaxies in the Coma cluster - implications for the structure of the fundamental plane

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