Large-scale shock-ionized and photo-ionized gas in M83: the impact of star formation

Abstract

We investigate the ionization structure of the nebular gas in M83 using the line diagnostic diagram, [O III](5007 \degA)/Hβ vs. [S II](6716 °A+6731 °A)/Hα with the newly available narrowband images from the Wide Field Camera 3 (WFC3) of the Hubble Space Telescope (HST). We produce the diagnostic diagram on a pixel-by-pixel (0.2" x 0.2") basis and compare it with several photo- and shock-ionization models. For the photo-ionized gas, we observe a gradual increase of the log([O III]/Hβ) ratios from the center to the spiral arm, consistent with the metallicity gradient, as the H II regions go from super solar abundance to roughly solar abundance from the center out. Using the diagnostic diagram, we separate the photo-ionized from the shock-ionized component of the gas. We find that the shock-ionized Hα emission ranges from ~2% to about 15-33% of the total, depending on the separation criteria used. An interesting feature in the diagnostic diagram is an horizontal distribution around log([O III]/Hβ) ~ 0. This feature is well fit by a shock-ionization model with 2.0 Z\odot metallicity and shock velocities in the range of 250 km/s to 350 km/s. A low velocity shock component, < 200 km/s, is also detected, and is spatially located at the boundary between the outer ring and the spiral arm. The low velocity shock component can be due to : 1) supernova remnants located nearby, 2) dynamical interaction between the outer ring and the spiral arm, 3) abnormal line ratios from extreme local dust extinction. The current data do not enable us to distinguish among those three possible interpretations. Our main conclusion is that, even at the HST resolution, the shocked gas represents a small fraction of the total ionized gas emission at less than 33% of the total. However, it accounts for virtually all of the mechanical energy produced by the central starburst in M83.

Accepted for publication in ApJ. aastex preprint 12pt, 21 pages, 13 figures

References in corpus (7)

• The MAPPINGS III Library of Fast Radiative Shock Models
• Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows
• An H-alpha Imaging Survey of Galaxies in the Local 11 Mpc Volume
• Mapping Large-Scale Gaseous Outflows in Ultraluminous Infrared Galaxies with Keck II ESI Spectra: Spatial Extent of the Outflow
• The Luminosity, Mass, and Age Distributions of Compact Star Clusters in M83 Based on HST/WFC3 Observations
• NGC 839: Shocks in an M82-like Superwind
• Gemini GMOS/IFU spectroscopy of NGC 1569 - II: Mapping the roots of the galactic outflow

Cited by in corpus (10)

• Star Formation Rates for photometric samples of galaxies using machine learning methods
• Resolving Ionisation and Metallicity on Parsec Scales Across Mrk 71 with HST-WFC3
• Spatially resolved physical conditions of molecular gas and potential star formation tracers in M83, revealed by the Herschel SPIRE FTS
• The centres of M83 and the Milky Way: opposite extremes of a common star formation cycle
• Constraining Stellar Feedback: Shock-ionized Gas in Nearby Starburst Galaxies
• Two physical regimes for the Giant HII Regions and Giant Molecular Clouds in the Antennae Galaxies
• Detection of Extraplanar Diffuse Ionized Gas in M83
• Quantitative Method for the Optimal Subtraction of Continuum Emission from Narrow-band Images : Skewness Transition Analysis
• Clues on Arp 142: The Spiral-Elliptical merger
• Deconstructing a galaxy: colour distributions of point sources in Messier 83