A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

II. Constraining the quenching time in the stripped galaxy NGC 4330

¹ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
e-mail: mfossati@mpe.mpg.de
² Universitäts-Sternwarte München, Scheinerstrasse 1, 81679 München, Germany
³ Aix Marseille Université, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, Marseille, France
e-mail: alessandro.boselli@lam.fr
⁴ CEA/IRFU/SAP, Laboratoire AIM Paris-Saclay, CNRS/INSU, Université Paris Diderot, Observatoire de Paris, PSL Research University, 91191 Gif-sur-Yvette Cedex, France
⁵ Observatoire Astronomique de Strasbourg, UMR 7750, 11 rue de l’Université, 67000 Strasbourg, France
⁶ INAF Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
⁷ NRC Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria BC V9E 2E7, Canada
⁸ Unidad de Astronomía, Fac. de Ciencias Basicas, Universidad de Antofagasta, Avda. U. de Antofagasta 02800, Antofagasta, Chile
⁹ International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
¹⁰ Department of Physics and Astronomy, Youngstown State University, Youngstown OH 44555, USA
¹¹ Institute for Computational Cosmology and Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
¹² Universitá di Milano-Bicocca, Piazza della scienza 3, 20100 Milano, Italy
¹³ Department of Astrophysics, University of Vienna, Turkenschanzstrasse 17, 1180 Vienna, Austria
¹⁴ Australia Telescope National Facility, CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia
¹⁵ Department of Astronomy, Peking University, Beijing 100871, PR China
¹⁶ Department of Physics and Astronomy, University of Alabama in Huntsville, Huntsville, AL 35899, USA
¹⁷ Department of Physics, University of the Pacific, 3601 Pacific Avenue, Stockton CA 95211, USA

Received: 28 November 2017
Accepted: 26 January 2018

Abstract

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Hα + [NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass (M_* ≃ 10^9.8 M_⊙) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous Hα observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness ~10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped ~500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H₂ gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.