%0 Journal Article
%T Surface Brightness Fluctuations of Fornax Cluster Galaxies: Calibration of Infrared Surface Brightness Fluctuations and Evidence for Recent Star Formation
%+ Institut d'Astrophysique de Paris (IAP)
%A Liu, Michael C.
%A Graham, James R.
%A Charlot, Stéphane
%< avec comité de lecture
%@ 0004-637X
%J The Astrophysical Journal
%I American Astronomical Society
%V 564
%P 216-233
%8 2002
%D 2002
%Z astro-ph/0107357
%Z 2002ApJ...564..216L
%R 10.1086/324262
%K Cosmology: Distance Scale
%K Galaxies: Distances and Redshifts
%K Galaxies: Elliptical and Lenticular
%K cD
%K Galaxies: Stellar Content
%K Infrared: Galaxies
%K Astrophysics
%Z Sciences of the Universe [physics]Journal articles
%X We have measured KS-band (2.0-2.3 μm) surface brightness fluctuations (SBFs) of 19 early-type galaxies in the Fornax Cluster. Fornax is ideally suited both for calibrating SBFs as distance indicators and for using SBFs to probe the unresolved stellar content of early-type galaxies. Combining our results with published data for other nearby clusters, we calibrate KS-band SBFs using Hubble Space Telescope (HST) Cepheid cluster distances and I-band SBF distances to individual galaxies. With the latter, the resulting calibration isMKS=(-5.84+/-0.04)+(3.6+/-0.8)[(V- Ic)0-1.15],valid for 1.05<(V-Ic)0<1.25 and not including any systematic errors in the HST Cepheid distance scale. The fit accounts for the covariance between V-Ic and MKS when calibrated in this fashion. The intrinsic cosmic scatter of MKS appears to be larger than that of I-band SBFs. S0 galaxies may follow a different relation, although the data are inconclusive. The discovery of correlation between KS-band fluctuation magnitudes and colors with V-Ic is a new clue into the star formation histories of early-type galaxies. This relation naturally accounts for galaxies previously claimed to have anomalously bright K-band SBFs, namely, M32 and NGC 4489. Models indicate that the stellar populations dominating the SBF signal have a significant range in age; some scatter in metallicity may also be present. The youngest ages imply some galaxies have very luminous giant branches, akin to those in intermediate-age (few Gyr) Magellanic Cloud clusters. The inferred metallicities are roughly solar, although this depends on the choice of theoretical models. A few Fornax galaxies have unusually bright KS-band SBFs, perhaps originating from a high-metallicity burst of star formation in the last few Gyr. The increased spread and brightening of the KS-band SBFs with bluer V-Ic suggest that the lower mass cluster galaxies (<~0.1L*) may have had more extended and more heterogeneous star formation histories than those of the more massive galaxies.
%G English
%L insu-03947325
%U https://insu.hal.science/insu-03947325
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%~ CNRS
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