Reconciliation of the Surface Brightness Fluctuation and Type Ia Supernova Distance Scales

We present Hubble Space Telescope measurements of surface brightnessfluctuations (SBF) distances to early-type galaxies that have hosted Type Iasupernovae (SNIa). The agreement in the relative SBF and SNIa multicolor lightcurve shape and delta-m_15 distances is excellent. There is no systematic scaleerror with distance, and previous work has shown that SBF and SNIa giveconsistent ties to the Hubble flow. However, we confirm a systematic offset ofabout 0.25 mag in the distance zero points of the two methods, and we tracethis offset to their respective Cepheid calibrations. SBF has in the past beencalibrated with Cepheid distances from the H_0 Key Project team, while SNIahave been calibrated with Cepheid distances from the team composed of Sandage,Saha, and collaborators. When the two methods are calibrated in a consistentway, their distances are in superb agreement. Until the conflict over the``long'' and ``short'' extragalactic Cepheid distances among many galaxies isresolved, we cannot definitively constrain the Hubble constant to better thanabout 10%, even leaving aside the additional uncertainty in the distance to theLarge Magellanic Cloud, common to both Cepheid scales. However, recenttheoretical SBF predictions from stellar population models favor the KeyProject Cepheid scale, while the theoretical SNIa calibration lies between thelong and short scales. In addition, while the current SBF distance to M31/M32is in good agreement with the RR Lyrae and red giant branch distances,calibrating SBF with the longer Cepheid scale would introduce a 0.3 mag offsetwith respect to the RR Lyrae scale.Comment: 13 pages, 3 PostScript figures, LaTeX with AASTeX 5.02 and natbib.sty v7.0 (included). Accepted for publication in The Astrophysical Journa