Near-infrared integral field spectroscopy of star-forming galaxies

Daniel A. Dale, Hélène Roussel, Alessandra Contursi, George Helou, Harriet L. Dinerstein, Deidre A. Hunter, David J. Hollenbach, Eiichi Egami, Keith Matthews, Thomas W. Murphy, Christine E. Lafon, Robert H. Rubin

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The Palomar Integral Field Spectrograph was used to probe a variety of environments in nine nearby galaxies that span a range of morphological types, luminosities, metallicities, and infrared-to-blue ratios. For the first time, near-infrared spectroscopy was obtained for nuclear or bright H II regions in star-forming galaxies over two spatial dimensions (5′.7 × 10′.0) in the [Fe II] (1.257 μm), [Fe II] (1.644 μm), Paβ (1.282 μm), H2 (2.122 μm), and Brγ (2.166 μm) transition lines. These data yield constraints on various characteristics of the star-forming episodes in these regions, including their strength, maturity, spatial variability, and extinction. The H II regions stand out from the nuclei. Unlike observations of nuclear regions, H II region near-infrared observations do not show a spatial coincidence of the line and continuum emission; the continuum and line maps of H II regions usually show distinct and sometimes spatially separated morphologies. Gauging from Paβ and Brγ equivalent widths and luminosities, the H II regions have younger episodes of star formation than the nuclei and more intense radiation fields. Near-infrared line ratio diagnostics suggest that H II regions have "purer" starbursting properties. The correlation between ionizing photon density and mid-infrared color is consistent with the star formation activity level being higher for H II regions than for nuclei. And though the interpretation is complicated, on a purely empirical basis the H II regions show lower Fe 1+ abundances than nuclei by an order of magnitude.

Original languageEnglish (US)
Pages (from-to)813-830
Number of pages18
JournalAstrophysical Journal
Volume601
Issue number2 I
DOIs
StatePublished - Feb 1 2004
Externally publishedYes

Keywords

  • Galaxies: ISM
  • H II regions
  • Infrared: galaxies
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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