A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

V. Properties of the ionised gas filament of M 87^⋆

¹ Aix-Marseille Univ., CNRS, CNES, LAM, Marseille, France
e-mail: alessandro.boselli@lam.fr
² Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
³ Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
⁴ Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, PR China
⁵ INAF – Osservatorio Astronomico di Brera, via Brera 28, 20159 Milano, Italy
⁶ Department of Physics and Astronomy, University of Alabama in Huntsville, Huntsville, AL 35899, USA
⁷ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
⁸ Centro de Astronomá (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile
⁹ Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
¹⁰ Collège de France, 11 Pl. M. Berthelot, 75005 Paris, France
¹¹ LERMA, Observatoire de Paris, CNRS, PSL Research University, Sorbonne Universités, UPMC Univ. Paris 06, 75014 Paris, France
¹² NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
¹³ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, Observatoire de Paris, PSL University, 91191 Gif-sur-Yvette Cedex, France
¹⁴ Observatoire Astronomique de Strasbourg, UMR 7750, 11 rue de l’Université, 67000 Strasbourg, France
¹⁵ Universitá di Milano-Bicocca, Piazza della Scienza 3, 20100 Milano, Italy
¹⁶ Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
¹⁷ Department of Astronomy, Peking University, Beijing 100871, PR China
¹⁸ Laboratório de Astrofísica Teórica e Observacional, Universidade Estadual de Santa Cruz, 45650-000 Ilhéus, BA, Brazil
¹⁹ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
²⁰ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
²¹ Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Cagliari, Italy

Received: 23 October 2018
Accepted: 4 December 2018

Abstract

We observed the giant elliptical galaxy M 87 during the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band Hα+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada French Hawaii Telescope (CFHT). The deep narrow-band image confirmed the presence of a filament of ionised gas extending up to ≃3 kpc in the north-western direction and ≃8 kpc to the southeast, with a couple of plumes of ionised gas, the weakest of which, at ≃18 kpc from the nucleus, was previously unknown. The analysis of deep optical images taken from the NGVS survey confirms that this gas filament is associated with dust seen in absorption which is now detected up to ≃2.4 kpc from the nucleus. We also analysed the physical and kinematical properties of the ionised gas filament using deep IFU MUSE data covering the central 4.8 × 4.8 kpc² of the galaxy. The spectroscopic data confirm a perturbed kinematics of the ionised gas, with differences in velocity of ≃700–800 km s⁻¹ on scales of ≲1 kpc. The analysis of 2D diagnostic diagrams and the observed relationship between the shock-sensitive [OI]/Hα line ratio and the velocity dispersion of the gas suggest that the gas is shock-ionised.