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Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2016

SDSS IV MaNGA - spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs

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Francesco Belfiore
  • Function : Author
Roberto Maiolino
  • Function : Author
Claudia Maraston
  • Function : Author
Matthew A. Bershady
  • Function : Author
Karen L. Masters
  • Function : Author
Renbin Yan
  • Function : Author
Dmitry Bizyaev
  • Function : Author
Médéric Boquien
  • Function : Author
Joel R. Brownstein
  • Function : Author
Kevin Bundy
  • Function : Author
Niv Drory
  • Function : Author
Timothy M. Heckman
  • Function : Author
David R. Law
  • Function : Author
Alexandre Roman-Lopes
  • Function : Author
Kaike Pan
  • Function : Author
Letizia Stanghellini
  • Function : Author
Daniel Thomas
  • Function : Author
Anne-Marie Weijmans
  • Function : Author
Kyle B. Westfall
  • Function : Author

Abstract

We study the spatially resolved excitation properties of the ionized gas in a sample of 646 galaxies using integral field spectroscopy data from the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) programme. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we demonstrate the ubiquitous presence of extended (kpc scale) low-ionization emission-line regions (LIERs) in both star-forming and quiescent galaxies. In star-forming galaxies LIER emission can be associated with diffuse ionized gas, most evident as extraplanar emission in edge-on systems. In addition, we identify two main classes of galaxies displaying LIER emission: `central LIER' (cLIER) galaxies, where central LIER emission is spatially extended, but accompanied by star formation at larger galactocentric distances, and `extended LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially flat, low H α equivalent width of line emission (<3 Å) and stellar population indices demonstrating the lack of young stellar populations, implying that line emission follows tightly the continuum due to the underlying old stellar population. The H α surface brightness radial profiles are always shallower than 1/r2 and the line ratio [O III] λ5007/[O II] λλ3727,29 (a tracer of the ionization parameter of the gas) shows a flat gradient. This combined evidence strongly supports the scenario in which LIER emission is not due to a central point source but to diffuse stellar sources, the most likely candidates being hot, evolved (post-asymptotic giant branch) stars. Shocks are observed to play a significant role in the ionization of the gas only in rare merging and interacting systems.
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insu-03710571 , version 1 (30-06-2022)

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Francesco Belfiore, Roberto Maiolino, Claudia Maraston, Eric Emsellem, Matthew A. Bershady, et al.. SDSS IV MaNGA - spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs. Monthly Notices of the Royal Astronomical Society, 2016, 461, pp.3111-3134. ⟨10.1093/mnras/stw1234⟩. ⟨insu-03710571⟩
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