Occurrence of LINER galaxies within the galaxy group environment

Coldwell, Georgina; Pereyra, Luis; Alonso, Santiago; Donoso, Emilio; Duplancic, Fernanda

doi:10.1093/mnras/stx294

Cited by 10 publications

(25 citation statements)

References 54 publications

(59 reference statements)

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“…The AGN ionizing field is likely not dominant in the optical domain, but according to our statistical study, the nuclear and jet activity must be present. This is also in agreement with the studies of Coldwell et al (2017Coldwell et al ( , 2018 where they find that LINERs are redder and older than the control sample of galaxies in environ-ments of different density. They also show that LINERs are likely to populate low-density regions in spite of their elliptical morphology, that is, their occurrence in low-density galaxy groups is two times higher than the occurrence of the control, non-LINER galaxies.…”

Section: Flat and Inverted Spectral Index Towards Liners: Implicationsupporting

confidence: 92%

“…The interpretation and the nature of LINERs remains still unclear and several recent studies have attempted to shed more light on their characteristics and the potential effect of the environment (Singh et al 2013;Coldwell et al 2017Coldwell et al , 2018. The fact that 50% of LINERS in both frequency ranges have flat to inverted spectral indices points to the activity of the nucleus and the dominant contribution of the core and the jet radio emission to the overall radio emission of LINER galaxies.…”

Section: Flat and Inverted Spectral Index Towards Liners: Implicationmentioning

confidence: 99%

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Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

Zajaček

Busch

Valencia-S.

et al. 2019

A&A

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Context. The empirical relations between supermassive black holes and their host spheroids point towards the crucial role of galactic nuclei in affecting the properties of their hosts. A detailed understanding of how the activity of a galactic nucleus regulates the growth of its host is still missing. Aims. To understand the activity and the types of accretion of supermassive black holes in different hosts, it is essential to study the radio-optical properties of a large sample of extragalactic sources. In particular, we aim to study the radio spectral index trends across the optical emission line diagnostic diagrams to search for potential (anti)correlations. Methods. To this goal, we combined flux densities from the radio FIRST survey at 1.4 GHz (with the flux density range 10 mJy ≤ F 1.4 ≤ 100 mJy) for 396 SDSS sources at intermediate redshift (0.04 ≤ z ≤ 0.4) with the Effelsberg radiotelescope measurements at 4.85 GHz and 10.45 GHz. The information about the optical emission-line ratios is obtained from the SDSS-DR7 catalogue. Results. Using the Effelsberg data, we were able to infer the two-point radio spectral index distributions for star-forming galaxies, composite galaxies (with a combined contribution to the line emission from the star formation and AGN activity), Seyferts, and low ionization narrow emission region (LINER) galaxies. Conclusions. While studying the distribution of steep, flat, and inverted sources across optical diagnostic diagrams, we found three distinct classes of radio emitters for our sample: (i) sources with a steep radio index, high ionization ratio, and high radio loudness, (ii) sources with a flat radio index, lower ionization ratio, and intermediate radio loudness, (iii) sources with an inverted radio index, low ionization ratio, and low radio loudness. The classes (i), (ii), and (iii) cluster mainly along the transition from Seyfert to LINER sources in the optical diagnostic (Baldwin, Phillips & Telervich; BPT) diagram. We interpret these groups as a result of the recurrent nuclear-jet activity.A&A proofs: manuscript no. zajacek_index different sections of the diagnostic diagrams have been traced back to systematic changes in the ionization parameter, the shape of the ionizing continuum, the fraction of matter-bound clouds, and/or the role of metal abundances.According to a given set of ratios, four spectral classes of galaxies are commonly distinguished. In star-forming galaxies (SF), the ionizing flux is provided mostly by hot, massive, young stars and associated supernovae that are surrounded by HII regions. They have lower [OIII]/Hβ and [NII]/Hα ratios than pure AGN sources (see also Figs. 1 and 2). In between SF and AGN sources are composite (COMP) galaxies, with a mixed contribution from star formation (HII regions) and AGN. The AGN spectral class was further subdivided into Seyfert 2 sources (Sy) and low-ionization nuclear emission regions (LINERs). LINERs are characterized by a lower [OIII]/Hβ ratio in comparison with Seyfert 2 AGN sources and a higher [NII]/Hα ratio wi...

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Section: Flat and Inverted Spectral Index Towards Liners: Implicationsupporting

confidence: 92%

Section: Flat and Inverted Spectral Index Towards Liners: Implicationmentioning

confidence: 99%

Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

Zajaček

Busch

Valencia-S.

et al. 2019

A&A

View full text Add to dashboard Cite

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“…Different studies demonstrated that the host galaxies of LINERs have a bulge-type morphology being more massive and luminous than a general galaxy sample (Yan et al 2006;Kewley et al 2006;Capetti & Baldi 2011;Coldwell et al 2017). This early-type galaxies are commonly found in dense galaxy environment as it is suggested by the morphology-density relation (Dressler 1980;Domínguez, Muriel & Lambas 2001).…”

Section: Discussionmentioning

confidence: 99%

“…Then, if the photoionization from AGNs is one of the mechanisms for the LINER emission we could expect that, at least, LINERs follow a similar trend that Seyfert 2 galaxies. On this way, Coldwell et al (2017) analysed the occurrence of SDSS-DR7 LINER galaxies with respect to their proximity to galaxy groups. The main results have shown that a higher percentage of LINER can be found populating low-density environment.…”

Section: Introductionmentioning

confidence: 99%

LINER galaxy properties and the local environment

Coldwell

Alonso

Duplancic

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We analyse the properties of a sample of 5560 LINER galaxies selected from SDSS-DR12, at low redshift, for a complete range of local density environments. The host LINER galaxies were studied and compared with a well-defined control sample of 5553 non-LINER galaxies matched in redshift, luminosity, morphology and local density. By studying the distributions of galaxy colours and stellar age population we find that LINERs are redder and older than the control sample in the wide range of densities. In addition, LINERs are older than the control sample, at a given galaxy colour, indicating that some external process could have accelerated the evolution of the stellar population.The analysis of the host properties shows that the control sample exhibits a strong relation between the colours, ages and the local density, while more than 90% of the LINERs are redder and older than the mean values, independently of the neighbourhood density. Furthermore, a detailed study in three local density ranges shows that, while control sample galaxies are redder and older as a function of its stellar mass and density, LINER galaxies mismatch the known morphology-density relation shown by galaxies without low-ionization features. The results give support to the contribution of hot and old stars as viable mechanisms for the low ionization emission although the presence of nuclear activity is not discarded.

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“…The results of these studies conclude a higher active galactic nucleus occurrence in lower/medium density environments at low redshifts. (Kauffmann et al 2004;Choi et al 2009;Sabater et al 2013;Coldwell et al 2014Coldwell et al , 2017. In addition, galaxy-galaxy interactions may produce gravitational instabilities providing gas to the most central regions of the galaxy and the growth by accretion of the central black holes.…”

Section: Introductionmentioning

confidence: 99%

The impact of void environment on AGN

Ceccarelli¹,

Duplancic²,

Lambas³

2021

Preprint

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We study the population of active galaxies in void environment in the SDSS. We use optical spectroscopic information to analyze characteristics of the emission lines of galaxies, accomplished by WHAN and BPT diagrams. Also, we study WISE mid-IR colours to assess AGN activity. We investigate these different AGN classification schemes, both optical and mid-IR, and their dependence on the spatial location with respect to the void centres. To this end, we define three regions: void, the spherical region defined by voidcentric distance relative to void radius (distance/r void ) smaller than 0.8, comprising overdensities lesser than -0.9, an intermediate/transition shell region (namely void-wall) 0.8 < distance/r void < 1.2, and a region sufficiently distant from voids, the field: distance/r void > 2. We find statistical evidence for a larger fraction of AGN and star-forming galaxies in the void region, regardless of the classification scheme addressed (either BPT, WHAN or WISE). Moreover, we obtain a significantly stronger nuclear activity in voids compared to the field. We find an unusually large fraction of the most massive black holes undergoing strong accretion when their host galaxies reside in voids. Our results suggest a strong influence of the void environment on AGN mechanisms associated with galaxy evolution.

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Occurrence of LINER galaxies within the galaxy group environment

Cited by 10 publications

References 54 publications

Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

Radio spectral index distribution of SDSS-FIRST sources across optical diagnostic diagrams

LINER galaxy properties and the local environment

The impact of void environment on AGN

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