The Lyman alpha reference sample

VII. Spatially resolved Hα kinematics^⋆,⋆⋆

¹ Leibniz-Institut far Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: cherenz@aip.de
² Lund Observatory, Box 43, 221 00 Lund, Sweden
³ Astronomical Institute, Academy of Sciences of the Czech Republic, Boční II 1401, 141 00 Prague, Czech Republic
⁴ Department of Astronomy, Oskar Klein Centre for Cosmoparticle Physics, Stockholm University, AlbaNova University Centre, 106 91 Stockholm, Sweden
⁵ Department of Physics & Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105, USA
⁶ Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706, USA
⁷ CONACyT research fellow – Instituto de Radioastronomía y Astrofísica, UNAM, Campus Morelia, Michoacán, CP 58089, Mexico
⁸ Centro de Astrobiología (CSIC–INTA), Departamento de Astrofísica, PO Box 78, 28691 Villanueva de la Cañada, Spain
⁹ Laboratoire d’Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire, 1290 Sauverny, Switzerland
¹⁰ Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8582 Chiba, Japan
¹¹ INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio, Italy
¹² Institut d’Astrophysique de Paris, UMR 7095 CNRS & UPMC, 98bis Bd Arago, 75014 Paris, France
¹³ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
¹⁴ Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Versoix, Switzerland
¹⁵ CNRS, IRAP, 14 Avenue E. Belin, 31400 Toulouse, France

Received: 15 September 2015
Accepted: 16 November 2015

Abstract

We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties of the LARS galaxies’ intrinsic Lyα radiation field. We show our kinematic maps that are spatially registered onto the Hubble Space Telescope Hα and Lyman α (Lyα) images. We can conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies, however, no general trend can be established for the whole sample. Furthermore, we compute the intrinsic velocity dispersion σ₀, the shearing velocity v_shear, and the v_shear/σ₀ ratio from our kinematic maps. In general LARS galaxies are characterised by high intrinsic velocity dispersions (54 km s^-1 median) and low shearing velocities (65 km s^-1 median). The v_shear/σ₀ values range from 0.5 to 3.2 with an average of 1.5. It is noteworthy that five galaxies of the sample are dispersion-dominated systems with v_shear/σ₀< 1, and are thus kinematically similar to turbulent star-forming galaxies seen at high redshift. When linking our kinematical statistics to the global LARS Lyα properties, we find that dispersion-dominated systems show higher Lyα equivalent widths and higher Lyα escape fractions than systems with v_shear/σ₀> 1. Our result indicates that turbulence in actively star-forming systems is causally connected to interstellar medium conditions that favour an escape of Lyα radiation.