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|Title:||SDSS IV MaNGA - spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs||Authors:||BELFIORE, FRANCESCO MICHEL CONCETTO
Bershady, Matthew A.
Masters, Karen L.
Brownstein, Joel R.
Heckman, Timothy M.
Law, David R.
Westfall, Kyle B.
|Issue Date:||2016||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||461||Issue:||3||First Page:||3111||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/r<SUP>2</SUP> 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.||URI:||http://hdl.handle.net/20.500.12386/29574||URL:||https://academic.oup.com/mnras/article/461/3/3111/2608476||ISSN:||0035-8711||DOI:||10.1093/mnras/stw1234||Bibcode ADS:||2016MNRAS.461.3111B||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Jan 18, 2021
checked on Jan 18, 2021
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