%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 %~ INSU %~ CNRS %~ IAP %~ SORBONNE-UNIVERSITE %~ SU-INF-2018 %~ SU-SCIENCES %~ SU-TI %~ ALLIANCE-SU