2013A&A...558A..43S


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST02:19:19

2013A&A...558A..43S - Astronomy and Astrophysics, volume 558A, 43-43 (2013/10-1)

The nature of LINER galaxies : Ubiquitous hot old stars and rare accreting black holes.

SINGH R., VAN DE VEN G., JAHNKE K., LYUBENOVA M., FALCON-BARROSO J., ALVES J., CID FERNANDES R., GALBANY L., GARCIA-BENITO R., HUSEMANN B., KENNICUTT R.C., MARINO R.A., MARQUEZ I., MASEGOSA J., MAST D., PASQUALI A., SANCHEZ S.F., WALCHER J., WILD V., WISOTZKI L., ZIEGLER B. (The CALIFA collaboration)

Abstract (from CDS):

Galaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisation nuclear emission line region (LINER). For 30 years, this was attributed to a central mass-accreting supermassive black hole (more commonly known as active galactic nucleus, AGN) of low luminosity, making LINER galaxies the largest AGN sub-population, which dominate in numbers over higher luminosity Seyfert galaxies and quasars. This, however, poses a serious problem. While the inferred energy balance is plausible, many LINERs clearly do not contain any other independent signatures of an AGN. Using integral field spectroscopic data from the CALIFA survey, we compare the observed radial surface brightness profiles with what is expected from illumination by an AGN. Essential for this analysis is a proper extraction of emission lines, especially weak lines, such as Balmer Hβ lines, which are superposed on an absorption trough. To accomplish this, we use the GANDALF code, which simultaneously fits the underlying stellar continuum and emission lines. For 48 galaxies with LINER-like emission, we show that the radial emission-line surface brightness profiles are inconsistent with ionisation by a central point-source and hence cannot be due to an AGN alone. The most probable explanation for the excess LINER-like emission is ionisation by evolved stars during the short but very hot and energetic phase known as post-AGB. This leads us to an entirely new interpretation. Post-AGB stars are ubiquitous and their ionising effect should be potentially observable in every galaxy with the gas present and with stars older than ∼1Gyr unless a stronger radiation field from young hot stars or an AGN outshines them. This means that galaxies with LINER-like emission are not a class defined by a property but rather by the absence of a property. It also explains why LINER emission is observed mostly in massive galaxies with old stars and little star formation.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: ISM - galaxies: nuclei - stars: AGB and post-AGB

Simbad objects: 4

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Number of rows : 4

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 4210 LIN 12 15 15.8479940774 +65 59 07.089820067   13.4       ~ 108 0
2 NGC 5216 GiP 13 32 06.9096470880 +62 42 02.417160507   16.80 16.14     ~ 108 0
3 NGC 5614 IG 14 24 07.591 +34 51 32.02   12.6       ~ 120 0
4 UGC 11680 Sy2 21 07 44.1 +03 52 31           ~ 87 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-02:19:19

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