A Sample of Seyfert-2 Galaxies With Ultraluminous Galaxy-Wide Narrow-Line Regions: Quasar Light Echoes?

Schirmer, M.; Díaz, Rubén; Holhjem, K.; Levenson, N. A.; Winge, Cláudia

doi:10.1088/0004-637x/763/1/60

Cited by 54 publications

(121 citation statements)

References 91 publications

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“…We have pursued detailed study of this subset of 8 (plus IC 2497/Hanny's Voorwerp) to learn more about AGN variations on the otherwise inaccessible range of time scales 10 4 − 10 5 years. Analogous cases of extended ionized gas near energetically inadequate AGN have been reported at higher redshift and luminosity by Schirmer et al (2013) and Schirmer et al (2016), their "Green Bean" systems, and at low luminosity in the local Universe in the merger remnant NGC 7252 (Schweizer et al 2013) and as one interpretation of an off-nuclear ionized region in the spiral galaxy NGC 3621 (Menezes et al 2016).…”

Section: Introductionsupporting

confidence: 56%

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗

Keel

Lintott

Maksym

et al. 2017

ApJ

101

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We consider the energy budgets and radiative history of eight fading AGN, identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on ≈ 50, 000-year timescales. We explore the use of minimum ionizing luminosity Q ion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar-Green (PG) QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGN, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGN in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈ 2 × 10 4 years before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 years. In the limit of largely obscured AGN, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from from infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGN, to simulations of AGN accretion; the strongest variations on these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission, morphologically suggestive of outflow, are common, their kinematic structure shows some to be in regular rotation. UGC 7342 exhibits local signatures of outflows < 300 km s −1 , largely associated with very diffuse emission, and possibly entraining gas in one of the clouds seen in HST images. Only in the Teacup AGN do we see outflow signatures of order 1000 km s −1 . In contrast to the extended emission regions around many radio-loud AGN, the clouds around these fading AGN consist largely of tidal debris being externally illuminated but not displaced by AGN outflows.

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Section: Introductionsupporting

confidence: 56%

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗

Keel

Lintott

Maksym

et al. 2017

ApJ

101

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“…More problematic could be the challenge of measuring some of these lines. For example, [Ne iii]λ3343 can potentially be blended with the [Ne v]λ3347 line (Schirmer et al 2013), while Si ii λ1814 has been found to be very weak in high-redshift quasars (Negrete et al 2014). …”

Section: Ne-based Diagnostics In the Near Ultravioletmentioning

confidence: 99%

Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths

Feltre¹,

Charlot²,

Gutkin³

2016

Mon. Not. R. Astron. Soc.

298

461

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In the context of observations of the rest-frame ultraviolet and optical emission from distant galaxies, we explore the emission-line properties of photoionization models of active and inactive galaxies. Our aim is to identify new line-ratio diagnostics to discriminate between gas photoionization by active galactic nuclei (AGN) and star formation. We use a standard photoionization code to compute the emission from AGN narrow-line regions and compare this with calculations of the nebular emission from star-forming galaxies achieved using the same code. We confirm the appropriateness of widely used optical spectral diagnostics of nuclear activity versus star formation and explore new diagnostics at ultraviolet wavelengths. We find that combinations of a collisionally excited metal line or line multiplet, such as C iv λλ1548, 1551,iii]λ1892 and [C iii]λ1907+C iii]λ1909, with the He ii λ1640 recombination line are individually good discriminants of the nature of the ionizing source. Diagrams involving at least 3 of these lines allow an even more stringent distinction between active and inactive galaxies, as well as valuable constraints on interstellar gas parameters and the shape of the ionizing radiation. Several line ratios involving Ne-based emission lines, such as [Ne iv]λ2424, [Ne iii]λ3343 and [Ne v]λ3426, are also good diagnostics of nuclear activity. Our results provide a comprehensive framework to identify the sources of photoionization and physical conditions of the ionized gas from the ultraviolet and optical nebular emission from galaxies. This will be particularly useful to interpret observations of high-redshift galaxies with future facilities, such as the James Webb Space Telescope and extremely large ground-based telescopes.

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“…The host is most likely a rare green bean galaxy (GBG; Schirmer et al 2013). The GBGs are extended objects (Petrosian radius r 2 Petro > ) and have g r 1.0 -> .…”

Section: Optical Propertiesmentioning

confidence: 99%

“…17 Petro =    , and with colors g r 1.02 0.04 -=  , r i 0.06 0.03 -=  , u r 2.36 0.20 -=  , and r z 0.57 0.05 -=  it is located in the region occupied by galaxies in Figure 2 of Cardamone et al (2009), outside the selection requirement for green bean galaxies. The host colors meet 11 of 12 selection criteria for selection of GBGs proposed by Schirmer et al (2013). We discuss this further in Section 4.2.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…The GBGs are ionization echoes of quasars experiencing a high activity episode and a subsequent rapid shut down. These galaxies are associated with shock or ionization fronts, including shocks of collimated jets heating the interstellar medium (Schirmer et al 2013;Davies et al 2015). We refer the reader to J. K. Banfield et al (2017, in preparation) on the detailed analysis of GBGs and their radio properties.…”

Section: Hymors As Quasarsmentioning

confidence: 99%

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Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Kapińska

Terentev²,

Wong

et al. 2017

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Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a largescale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies (L 4.7 10 median 24=´W Hz −1 sr −1 ) at redshifts z 0.14 1.0 < < . Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high-and two as low-excitation galaxies. Two candidate HyMoRS are giant ( 1 > Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

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A Sample of Seyfert-2 Galaxies With Ultraluminous Galaxy-Wide Narrow-Line Regions: Quasar Light Echoes?

Cited by 54 publications

References 91 publications

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗

Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

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A Sample of Seyfert-2 Galaxies With Ultraluminous Galaxy-Wide Narrow-Line Regions: Quasar Light Echoes?

Cited by 54 publications

References 91 publications

Fading AGN Candidates: AGN Histories and Outflow Signatures∗

Fading AGN Candidates: AGN Histories and Outflow Signatures∗

Nuclear activity versus star formation: emission-line diagnostics at ultraviolet and optical wavelengths

Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies

Contact Info

Product

Resources

About

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗

Fading AGN Candidates: AGN Histories and Outflow Signatures^∗