Globular Clusters in Fornax: Does $M^0$ Depend on Environment?

Abstract

We present the $V$-band globular cluster luminosity functions (GCLFs) of the Fornax Cluster galaxies NGC 1344, NGC 1380, NGC 1399, and NGC 1404. Our observations reach to $V=24.8$, roughly one magnitude beyond the GCLF turnover $m_V^0$, with $\sim 90\%$ completeness. From the amplitude of the galaxy surface brightness fluctuations, we also estimate the number of globular clusters fainter than this cutoff magnitude. The GCLFs of these galaxies are well fitted by Gaussians; the weighted means of their turnover magnitudes and dispersions are $⟨m_V^0⟩=23.88\pm 0.10$ mag and $⟨\sigma ⟩=1.35\pm 0.07$ mag. The assumption of a universal value for the absolute magnitude of the turnover $M_V^0$ places the Fornax cluster $0.13\pm 0.11$ mag more distant than Virgo. However, in light of recent Cepheid and other high-precision distance measurements, as well as ongoing HST observations of GCLFs for the purpose of determining the extra-galactic distance scale, we choose to re-examine the universal GCLF hypothesis. Based on data from groups and clusters of galaxies, we find evidence that $M_V^0$ becomes fainter as the local density of galaxies increases. We speculate on the possible cause of this trend; if it is confirmed, GCLF observations will be less useful for determining distances, but may provide important information for constraining theories of star formation in primordial galaxy halos.

Accepted for publication in the Astrophysical Journal Letters; eight pages including figures, uses aas2pp4.sty (included)

References in corpus (2)

• Determination of the Hubble constant from observations of Cepheid variables in the galaxy M96
• Globular Cluster Systems As Distance Indicators: Metallicity Effects On The Luminosity Function

Cited by in corpus (21)

• The ACS Fornax Cluster Survey. V. Measurement and Recalibration of Surface Brightness Fluctuations and a Precise Value of the Fornax--Virgo Relative Distance
• The HST Key Project on the Extragalactic Distance Scale XXVI. The Calibration of Population II Secondary Distance Indicators and the Value of the Hubble Constant
• A Database of Cepheid Distance Moduli and TRGB, GCLF, PNLF and SBF Data Useful for Distance Determinations
• The ACS Fornax Cluster Survey. VIII. The Luminosity Function of Globular Clusters in Virgo and Fornax Early-Type Galaxies and its Use as a Distance Indicator
• Globular cluster luminosity function as distance indicator
• Stellar Populations and Surface Brightness Fluctuations: New Observations and Models
• Measuring Distances Using Infrared Surface Brightness Fluctuations
• Radial Velocities of Globular Clusters in the Giant Elliptical Galaxy NGC 1399
• HST Imaging of the Globular Clusters in the Fornax Cluster: Color and Luminosity Distributions
• Globular Clusters in Dense Clusters of Galaxies
• The M31 Globular Cluster Luminosity Function
• Towards an Understanding of the Globular Cluster Over--abundance around the Central Giant Elliptical NGC 1399
• Surface Brightness Fluctuations of Fornax Cluster Galaxies: Calibration of Infrared SBFs and Evidence for Recent Star Formation
• The Far Field Hubble Constant
• Globular cluster candidates within the Fornax Cluster: intracluster globulars?
• The Carnegie Chicago Hubble Program X: Tip of the Red Giant Branch Distances to NGC 5643 and NGC 1404
• The Globular Cluster Systems in the Coma Ellipticals. I: The Luminosity Function in NGC 4874, and Implications for Hubble's Constant
• The distance to NGC1316 (Fornax A): yet another curious case
• Isolated ellipticals and their globular cluster systems III. NGC 2271, NGC 2865, NGC 3962, NGC 4240 and IC 4889
• The Globular Cluster System of NGC 1316 (Fornax A)
• The old globular cluster system of the dIrr galaxy NGC1427A in the Fornax cluster