The 3D structure of the Virgo cluster from H-band Fundamental Plane and Tully-Fisher distance determinations

We undertook a surface photometry survey of 200 galaxies in the Virgo cluster (complete to B<14.0 mag) carried out in the near-infrared (NIR) H band. Combining velocity dispersion measurements from the literature with new spectroscopic data for 11 galaxies, we derive distances of 59 early-type galaxies using the Fundamental Plane (FP) method. The distances of another 75 late-type galaxies are determined using the Tully-Fisher (TF) method. For this purpose we use the maximum rotational velocity, as derived from HI spectra from the literature, complemented with new Hα rotation curves of eight highly HI-deficient galaxies. The zero-points of the FP and TF template relations are calibrated assuming the distance modulus of Virgo mu_0=31.0, as determined with the Cepheids method. Using these 134 distance determinations (with individual uncertainties of 0.35 mag (TF) and 0.45 mag (FP)) we find that the distance of cluster A, associated with M87, is mu_0=30.84 +/- 0.06. Cluster B, offset to the south, is found at mu_0=31.84 +/- 0.10. This subcluster is falling on to A at about 750 km s^-1. Clouds W and M are at twice the distance of A. Galaxies on the north-west and south-east of the main cluster A belong to two clouds composed almost exclusively of spiral galaxies with distances consistent with A, but with significantly different velocity distributions, suggesting that they are falling on to cluster A at approximately 770 km s^-1 from the far side and at 200 km s^-1 from the near side respectively. The mass of Virgo inferred from the peculiar motions induced on its vicinity is consistent with the virial expectation.