THE NATURE OF LINER-LIKE EMISSION IN RED GALAXIES

By R. Yan, M. Blanton. 2011

173 citations recorded by the source corpus.

Passive red galaxies frequently contain warm ionized gas and have spectra similar to low-ionization nuclear emission-line regions (LINERs). Here we investigate the nature of the ionizing sources powering this emission, by comparing nuclear spectroscopy from the Palomar survey with larger aperture data from the Sloan Digital Sky Survey. We find the line emission in the majority of passive red galaxies is spatially extended; the Hα surface brightness profile depends on radius r as r−1.28. We detect strong line ratio gradients with radius in [N ii]/Hα, [S ii]/Hα, and [O iii]/[S ii], requiring the ionization parameter to increase outward. Combined with a realistic gas density profile, this outward increasing ionization parameter convincingly rules out active galactic nuclei (AGNs) as the dominant ionizing source and strongly favors distributed ionizing sources. Sources that follow the stellar density profile can additionally reproduce the observed luminosity dependence of the line ratio gradient. Post-asymptotic giant branch stars provide a natural ionization source candidate, though they have an ionization parameter deficit. Velocity width differences among different emission lines disfavor shocks as the dominant ionization mechanism, and suggest that the interstellar medium in these galaxies contains multiple components. We conclude that the line emission in most LINER-like galaxies found in large-aperture (>100 pc) spectroscopy is not primarily powered by AGN activity and thus does not trace the AGN bolometric luminosity. However, they can be used to trace warm gas in these red galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/422f6553ef0bc1323ae8d40bd2c2785648ac5f71

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In Astronomy and Astrophysics

1. C. Conroy
2. P. Hopkins
3. R. Dav'e
4. L. Hernquist
5. R. Somerville
6. R. Maiolino
7. Lisa J. Kewley
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In Instrumentation

1. C. Conroy
2. R. Dav'e
3. P. Hopkins
4. L. Hernquist
5. M. Cappellari
6. D. M. Alexander
7. M. Blanton
8. R. Somerville

Citations in the corpus

• A STELLAR MASS THRESHOLD FOR QUENCHING OF FIELD GALAXIES (2012, methodology): “The NSA catalog galaxy also provides a re-analysis of the SDSS spectroscopic data for each galaxy using the techniques of Yan & Blanton (2012) and the SDSS spectrophotometric recalibration of Yan (2011).”
• RELATIONS BETWEEN CENTRAL BLACK HOLE MASS AND TOTAL GALAXY STELLAR MASS IN THE LOCAL UNIVERSE (2015, methodology): “The NSA also provides a reanalysis of spectroscopic data from the SDSS using the methods described in Yan & Blanton (2012) and Yan (2011).”
• A BUDGET AND ACCOUNTING OF METALS AT z ∼ 0: RESULTS FROM THE COS-HALOS SURVEY (2013, methodology): “It is possible, though, that passive galaxies with low-ionization emission (i.e., Liners) could have their interstellar metal content probed with analogous methods (Yan & Blanton 2012).”
• The nature of LINER galaxies: Ubiquitous hot old stars and rare accreting black holes (2013, background): “…hypothesis, and either predicted emission line strengths (Cid Fernandes et al. 2011) or the spatial distribution of LINER-like ionised regions in the galaxies (Sarzi et al. 2010; Yan & Blanton 2012), but neither were conclusive, because they either lacked full spatial or spectral information.”
• SDSS IV MaNGA – spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs (2016, methodology): “Finally, other sources of ionising radiation, such as low-mass X-ray binaries and extreme horizontal branch stars, have been found to be a subdominant contribution with respect to pAGB stars by at least one order of magnitude (Sarzi et al. 2010; Yan & Blanton 2012).”
• THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, background): “Aged stellar populations in post-starburst galaxies can also produce line ratios typical of LINERs (Taniguchi et al. 2000; Stasińska et al. 2008; Yan & Blanton 2012; Kehrig et al. 2012).”
• DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES (2013, methodology): “The spectroscopic data is re-analyzed using the methods of Yan & Blanton (2012) and Yan (2011).”
• Nebular Continuum and Line Emission in Stellar Population Synthesis Models (2016, background): “The leading candidate for the ionizing source is the population of post-AGB stars (Binette et al. 1994; Sarzi et al. 2010; Yan & Blanton 2012).”
• BLACK HOLE VARIABILITY AND THE STAR FORMATION–ACTIVE GALACTIC NUCLEUS CONNECTION: DO ALL STAR-FORMING GALAXIES HOST AN ACTIVE GALACTIC NUCLEUS? (2013, background): “…the low-Eddington optical AGN population are likely to be powered by evolved stellar populations, rather than BH accretion (e.g., Sarzi et al. 2010; Yan & Blanton 2012; Singh et al. 2013), although the effects of this contamination on the derived Eddington ratio distribution are difficult to…”
• SDSS-IV MaNGA : the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements (2016, background): “…[N ii]/Hα and [S ii]/Hα of DIG would move the position of a star-forming galaxy toward the composite or LI(N)ER region (e.g., Sarzi et al 2006; Stasińska et al. 2008; Yan & Blanton 2012; Kehrig et al. 2012; Singh et al. 2013; Gomes et al. 2016; Belfiore et al. 2016a,b) on the BPT diagrams.”
• Determining Inclinations of Active Galactic Nuclei Via Their Narrow-Line Region Kinematics (2012, background): “Though these velocities may be due to projected outflows, they could instead be a combination of rotation and ionization via star formation or post-AGB stars (Yan & Blanton 2012).”
• A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA (2013, result): “As discussed in Papaderos et al. (2013), and in line with a substantial body of previous works (Sarzi et al. 2010; Annibali et al. 2010; Yan & Blanton 2012; Kehrig et al. 2012, among others), various A49, page 4 of 25 lines of evidence suggest that photoionization by post-AGB stars appears to be…”
• Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, background): “Due to the uncertain nature of LINERs (e.g. Stasinska et al. 2008; Cid Fernandes et al. 2011; Yan & Blanton 2012), it is preferable to restrict ourselves to Seyfert-like spectra and we therefore impose a S/N > 5 requirement on the BPT lines for this basic classification.”
• The Coevolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe (2014, background): “Stasinska et al. (2008), Sarzi et al. (2010), Cid Fernandes et al. (2011), Capetti & Baldi (2011), and Yan & Blanton (2012) have all presented evidence that those LINERs with the weakest emission-lines (which are located in galaxies with predominantly old stars) are not powered by an AGN.”