Extended emission-line region

An extended emission-line region (EELR) is a giant interstellar cloud ionized by the radiation of an active galactic nucleus (AGN) inside a galaxy or photons produced by the shocks associated with the radio jets. An EELR can appear as a resolved cloud in relative nearby galaxies and as narrow emission lines in more distant galaxies.

File:Emmaalexander unified agn.png

EELRs were first discovered in radio galaxies. Usually the clouds emitting the narrow emission lines are restricted to a few kiloparsecs within the AGN, but some galaxies have narrow emission lines that extend a few kiloparsec to over 100 kiloparsecs. These clouds where therefore called extended emission-line regions (EELRs) and usually have a large doubly ionized oxygen [O III]/Hβ ratio, as well as a strong ionized helium He II/Hβ ratio (oxygen line at 5007 Å, helium line at 4686 Å). In some cases these EELRs show highly ionized species, such as calcium [Ca V] and iron [Fe VII] [Fe X]. Another common highly ionized species is the emission of neon [Ne V] (main line at 3426 Å). This high level of ionization shows that the EELRs must be ionized by a mechanism related to the nucleus of the galaxy. HII regions do not show this high level of ionization.{{Cite journal |last1=Robinson |first1=A. |last2=Binette |first2=L. |last3=Fosbury |first3=R. A. E. |last4=Tadhunter |first4=C. N. |date=1987-07-01 |title=Emission-line activity in radio galaxies. |journal=Monthly Notices of the Royal Astronomical Society |volume=227 |pages=97–114 |doi=10.1093/mnras/227.1.97 |doi-access=free |bibcode=1987MNRAS.227...97R |issn=0035-8711}} The first [O III] images of EELRs were around galaxies, such as 3C 79,{{Cite journal |last1=Fu |first1=Hai |last2=Stockton |first2=Alan |date=2008-04-01 |title=The Host Galaxy and the Extended Emission-Line Region of the Radio Galaxy 3C 79 |url=https://ui.adsabs.harvard.edu/abs/2008ApJ...677...79F |journal=The Astrophysical Journal |volume=677 |issue=1 |pages=79–91 |doi=10.1086/529015 |arxiv=0712.4145 |bibcode=2008ApJ...677...79F |issn=0004-637X}} 4C 37.43,{{Cite journal |last1=Fu |first1=Hai |last2=Stockton |first2=Alan |date=2007-09-01 |title=Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43 |url=https://ui.adsabs.harvard.edu/abs/2007ApJ...666..794F |journal=The Astrophysical Journal |volume=666 |issue=2 |pages=794–805 |doi=10.1086/520530 |arxiv=0705.4365 |bibcode=2007ApJ...666..794F |issn=0004-637X}} NGC 3516{{Cite journal |last1=Golev |first1=V. |last2=Yankulova |first2=I. |last3=Bonev |first3=T. |last4=Jockers |first4=K. |date=1995-03-01 |title=New narrow-band imaging of the extended emission-line region in the Seyfert galaxy NGC 3516 |journal=Monthly Notices of the Royal Astronomical Society |volume=273 |issue=1 |pages=129–138 |doi=10.1093/mnras/273.1.129 |doi-access=free |bibcode=1995MNRAS.273..129G |issn=0035-8711}} or NGC 4151.{{Cite journal |last1=Yoshida |first1=Michitoshi |last2=Ohtani |first2=Hiroshi |date=1993-06-01 |title=A Study of the Extended Emission-Line Region of the Seyfert Galaxy NGC 4151 by Means of Narrow-Band Imaging Observations |url=https://ui.adsabs.harvard.edu/abs/1993PASJ...45..407Y |journal=Publications of the Astronomical Society of Japan |volume=45 |pages=407–420 |bibcode=1993PASJ...45..407Y |issn=0004-6264}}

In 2009 a large cloud was discovered that had similar spectral features as EELRs, but had no ionizing AGN nearby. It was concluded that the nearby galaxy IC 2497 hosted an AGN in the past. Today this AGN faded into inactivity. The hard ionizing radiation did however need time to travel the thousands of lightyears towards a cloud, which would later become Hanny's Voorwerp. This makes Hanny's Voorwerp the first EELR associated with a fading AGN. Previously EELRs were commonly first discovered via spectroscopy and required high-resolution imaging to further resolve the EELRs. Hanny's Voorwerp was however discovered in broad band imaging from the Sloan Digital Sky Survey.{{Cite journal |last1=Lintott |first1=Chris J. |last2=Schawinski |first2=Kevin |last3=Keel |first3=William |last4=van Arkel |first4=Hanny |last5=Bennert |first5=Nicola |last6=Edmondson |first6=Edward |last7=Thomas |first7=Daniel |last8=Smith |first8=Daniel J. B. |last9=Herbert |first9=Peter D. |last10=Jarvis |first10=Matt J. |last11=Virani |first11=Shanil |last12=Andreescu |first12=Dan |last13=Bamford |first13=Steven P. |last14=Land |first14=Kate |last15=Murray |first15=Phil |date=2009-10-01 |title=Galaxy Zoo: 'Hanny's Voorwerp', a quasar light echo? |journal=Monthly Notices of the Royal Astronomical Society |volume=399 |issue=1 |pages=129–140 |doi=10.1111/j.1365-2966.2009.15299.x |doi-access=free |arxiv=0906.5304 |bibcode=2009MNRAS.399..129L |issn=0035-8711}} This prompted a search for more EELRs in broad-band imaging surveys by galaxy zoo volunteers, who also discovered Hanny's Voorwerp. EELRs are called "Voorwerpjes" by the galaxy zoo members.{{Cite journal |last1=Keel |first1=William C. |last2=Chojnowski |first2=S. Drew |last3=Bennert |first3=Vardha N. |last4=Schawinski |first4=Kevin |last5=Lintott |first5=Chris J. |last6=Lynn |first6=Stuart |last7=Pancoast |first7=Anna |last8=Harris |first8=Chelsea |last9=Nierenberg |first9=A. M. |last10=Sonnenfeld |first10=Alessandro |last11=Proctor |first11=Richard |date=2012-02-01 |title=The Galaxy Zoo survey for giant AGN-ionized clouds: past and present black hole accretion events |journal=Monthly Notices of the Royal Astronomical Society |volume=420 |issue=1 |pages=878–900 |doi=10.1111/j.1365-2966.2011.20101.x |doi-access=free |arxiv=1110.6921 |bibcode=2012MNRAS.420..878K |issn=0035-8711}} EELRs that are ionized by the AGN of a companion galaxy were also discovered. This type of ionization is called cross-ionization.

In broad-band images the [O III] emission lines usually lie at the g-band. The true color of an EELR would be dominated by the [O III] emission, which is a cyan color. In astronomical imaging slightly false-color images that transform g, r and i bands into RGB-images are more common. Sometimes the i-band is replaced with a z-band image. The EELRs appear as blue (g-band) objects in these survey images. Sometimes the H-alpha line is redshifted enough to lie at the i-band, which can make the EELR appear as a blue-violet object in these survey images. Sometimes the [O III] is redshifted enough that this line overlaps with the r-band or i-band, which makes them green or red in survey images of the Hyper Suprime-Cam.{{Cite journal |last1=Sun |first1=Ai-Lei |last2=Greene |first2=Jenny E. |last3=Zakamska |first3=Nadia L. |last4=Goulding |first4=Andy D. |last5=Strauss |first5=Michael A. |last6=Huang |first6=Song |last7=Johnson |first7=Sean D. |last8=Kawaguchi |first8=Toshihiro |last9=Matsuoka |first9=Yoshiki |last10=Marsteller |first10=Alisabeth A. |last11=Nagao |first11=Tohru |last12=Toba |first12=Yoshiki |date=2018-10-01 |title=Imaging extended emission-line regions of obscured AGN with the Subaru Hyper Suprime-Cam Survey |journal=Monthly Notices of the Royal Astronomical Society |volume=480 |issue=2 |pages=2302–2323 |doi=10.1093/mnras/sty1394 |doi-access=free |arxiv=1803.07241 |bibcode=2018MNRAS.480.2302S |issn=0035-8711}} At around 0.1 < z < 0.38 the 5006.843 Å [O III] line is redshifted to the r-band and at 0.38 < z < 0.68 it is redshifted to the i-band.{{r|g=note|r=Calculated with the formula z=(λ_observe-λ_emit)/λ_emit and the transition of SDSS filters from Figure 2 in Smith et al. 2002{{Cite journal |last1=Smith |first1=J. Allyn |last2=Tucker |first2=Douglas L. |last3=Kent |first3=Stephen |last4=Richmond |first4=Michael W. |last5=Fukugita |first5=Masataka |last6=Ichikawa |first6=Takashi |last7=Ichikawa |first7=Shin-ichi |last8=Jorgensen |first8=Anders M. |last9=Uomoto |first9=Alan |last10=Gunn |first10=James E. |last11=Hamabe |first11=Masaru |last12=Watanabe |first12=Masaru |last13=Tolea |first13=Alin |last14=Henden |first14=Arne |last15=Annis |first15=James |date=2002-04-01 |title=The u'g'r'i'z' Standard-Star System |url=https://ui.adsabs.harvard.edu/abs/2002AJ....123.2121S |journal=The Astronomical Journal |volume=123 |issue=4 |pages=2121–2144 |doi=10.1086/339311 |issn=0004-6256|arxiv=astro-ph/0201143 |bibcode=2002AJ....123.2121S }}}} A team of researchers detected a resolved EELR at a high redshift of 4.54 in a galaxy protocluster with JWST.

Another related type of cloud is a extended narrow-line region (ENLR). The EELRs usually have dynamically chaotic structures and high velocities and are probably the result of mergers. ENLRs on the other hand follow the disk structure of the galaxy and have a low velocity.

Recently a connection between EELRs and Tidal Disruption Events (TDE), as well as quasi-periodic X-ray eruption (QPE) was found. This connection is explained with TDEs and QPEs favouring a gas-rich post-merger environment. It is possible that repeated TDEs could power EELRs. On the other hand a fading AGN could result in an increase of the rate of TDEs.

List of resolved EELRs

This is a list of EELRs with resolved [O III] images or other emission-lines

class="wikitable"

!Name Host galaxy

!Image EELR

!Distance to nucleus (kpc)

!Date/Reference

MR 2251-178

|File:MR 2251-178 MUSE.jpg

|30-50

|1990{{Cite journal |last1=Macchetto |first1=F. |last2=Colina |first2=L. |last3=Golombek |first3=D. |last4=Perryman |first4=M. A. C. |last5=di Serego Alighieri |first5=S. |date=1990-06-01 |title=The Structure and Ionization of the Extended Emission-Line Filaments Surrounding the QSO MR 2251-178 |url=https://ui.adsabs.harvard.edu/abs/1990ApJ...356..389M |journal=The Astrophysical Journal |volume=356 |pages=389 |doi=10.1086/168847 |bibcode=1990ApJ...356..389M |issn=0004-637X}}

Centaurus A

outer and inner filaments

|File:Centaurus A filaments (EELRs).jpg

|7 & 16

|1991{{Cite journal |last1=Morganti |first1=R. |last2=Robinson |first2=A. |last3=Fosbury |first3=R. A. E. |last4=di Serego Alighieri |first4=S. |last5=Tadhunter |first5=C. N. |last6=Malin |first6=D. F. |date=1991-03-01 |title=The nature of the optical filaments in Centaurus A. Evidence for a beamed ionizing continuum. |journal=Monthly Notices of the Royal Astronomical Society |volume=249 |pages=91–112 |doi=10.1093/mnras/249.1.91 |doi-access=free |bibcode=1991MNRAS.249...91M |issn=0035-8711}}

IC 5063

|File:IC 5063 MUSE.jpg

|22

|1991{{Cite journal |last1=Colina |first1=L. |last2=Sparks |first2=W. B. |last3=Macchetto |first3=F. |date=1991-03-01 |title=IC 5063: A Merger Remnant with a Hidden Luminous Active Nucleus |url=https://ui.adsabs.harvard.edu/abs/1991ApJ...370..102C |journal=The Astrophysical Journal |volume=370 |pages=102 |doi=10.1086/169795 |bibcode=1991ApJ...370..102C |issn=0004-637X}}

3CR 368

|45

|1991{{Cite journal |last1=Hammer |first1=F. |last2=Le Fevre |first2=O. |last3=Proust |first3=D. |date=1991-06-01 |title=Deep Spectroscopy under High Spatial Resolution of the High-Redshift Radio Source 3CR 368: The Monster Elucidated |url=https://ui.adsabs.harvard.edu/abs/1991ApJ...374...91H |journal=The Astrophysical Journal |volume=374 |pages=91 |doi=10.1086/170099 |bibcode=1991ApJ...374...91H |issn=0004-637X}}

3C 352

|15.6

|1992{{Cite journal |last1=Hippelein |first1=Hans |last2=Meisenheimer |first2=Klaus |date=1992-10-01 |title=The extended line-emission from 3C 352. |url=https://ui.adsabs.harvard.edu/abs/1992A&A...264..472H |journal=Astronomy and Astrophysics |volume=264 |pages=472 |bibcode=1992A&A...264..472H |issn=0004-6361}}

NGC 4151

|File:Seyfert galaxy NGC4151 (GL-2002-001035).jpg

|1.16

|1993

NGC 3516

|File:NGC 3516.png

|1995

3C 273

|File:3C 273 MUSE.jpg

|14.4

|1996{{Cite journal |last1=Hippelein |first1=H. |last2=Meisenheimer |first2=K. |last3=Roeser |first3=H. J. |date=1996-12-01 |title=An emission line region associated with 3C 273. |url=https://ui.adsabs.harvard.edu/abs/1996A&A...316...29H |journal=Astronomy and Astrophysics |volume=316 |pages=29–32 |bibcode=1996A&A...316...29H |issn=0004-6361}}

PKS 2250–41

|File:PKS 2250–41 legacy surveys.jpg

|40-65

|1997{{Cite journal |last1=Clark |first1=N. E. |last2=Tadhunter |first2=C. N. |last3=Morganti |first3=R. |last4=Killeen |first4=N. E. B. |last5=Fosbury |first5=R. A. E. |last6=Hook |first6=R. N. |last7=Siebert |first7=J. |last8=Shaw |first8=M. A. |date=1997-04-01 |title=Radio, optical and X-ray observations of PKS 2250-41: a jet/galaxy collision? |journal=Monthly Notices of the Royal Astronomical Society |volume=286 |issue=3 |pages=558–582 |doi=10.1093/mnras/286.3.558 |doi-access=free |bibcode=1997MNRAS.286..558C |issn=0035-8711}}

NGC 5643

|File:Center of galaxy NGC 5643.tif

|1.8

|1997{{cite journal |last1=Simpson |first1=Chris |last2=Wilson |first2=A. S. |last3=Bower |first3=Gary |last4=Heckman |first4=T. M. |last5=Krolik |first5=J. H. |last6=Miley |first6=G. K. |date=January 1997 |title=A One-sided Ionization Cone in the Seyfert 2 Galaxy NGC 5643 |journal=The Astrophysical Journal |volume=474 |issue=1 |pages=121–128 |bibcode=1997ApJ...474..121S |doi=10.1086/303466 |doi-access=free}}

PKS 2356–61

|25

|1998{{Cite journal |last1=Koekemoer |first1=Anton M. |last2=Bicknell |first2=Geoffrey V. |date=1998-04-01 |title=Dynamics and Excitation of Radio Galaxy Emission-Line Regions. I. PKS 2356-61 |url=https://ui.adsabs.harvard.edu/abs/1998ApJ...497..662K |journal=The Astrophysical Journal |volume=497 |issue=2 |pages=662–680 |doi=10.1086/305490 |arxiv=astro-ph/9711229 |bibcode=1998ApJ...497..662K |issn=0004-637X}}

NGC 5256

|File:An ongoing cosmic collision.jpg

|2000{{Cite journal |last1=Ishigaki |first1=Tsuyoshi |last2=Yoshida |first2=Michitoshi |last3=Aoki |first3=Kentaro |last4=Ohtani |first4=Hiroshi |last5=Sugai |first5=Hajime |last6=Hayashi |first6=Tadashi |last7=Ozaki |first7=Shinobu |last8=Hattori |first8=Takashi |last9=Ishii |first9=Motomi |date=2000-02-01 |title=Tridimensional Spectrophotometric Study of the Extended Emission-Line Regions of the Infrared-Luminous Merger Markarian 266 |url=https://ui.adsabs.harvard.edu/abs/2000PASJ...52..185I |journal=Publications of the Astronomical Society of Japan |volume=52 |pages=185–207 |doi=10.1093/pasj/52.1.185 |bibcode=2000PASJ...52..185I |issn=0004-6264}}

NGC 4388

|File:Eso0304c.jpg

|35

|2002{{Cite journal |last1=Yoshida |first1=Michitoshi |last2=Yagi |first2=Masafumi |last3=Okamura |first3=Sadanori |last4=Aoki |first4=Kentaro |last5=Ohyama |first5=Youichi |last6=Komiyama |first6=Yutaka |last7=Yasuda |first7=Naoki |last8=Iye |first8=Masanori |last9=Kashikawa |first9=Nobunari |last10=Doi |first10=Mamoru |last11=Furusawa |first11=Hisanori |last12=Hamabe |first12=Masaru |last13=Kimura |first13=Masahiko |last14=Miyazaki |first14=Masayuki |last15=Miyazaki |first15=Satoshi |date=2002-03-01 |title=Discovery of a Very Extended Emission-Line Region around the Seyfert 2 Galaxy NGC 4388 |url=https://ui.adsabs.harvard.edu/abs/2002ApJ...567..118Y |journal=The Astrophysical Journal |volume=567 |issue=1 |pages=118–129 |doi=10.1086/338353 |arxiv=astro-ph/0110473 |bibcode=2002ApJ...567..118Y |issn=0004-637X}}

4C 37.43

|20

|2002{{Cite journal |last1=Stockton |first1=Alan |last2=MacKenty |first2=John W. |last3=Hu |first3=Esther M. |last4=Kim |first4=Tae-Sun |date=2002-06-01 |title=The Extended Emission-Line Region of 4C 37.43 |url=https://ui.adsabs.harvard.edu/abs/2002ApJ...572..735S |journal=The Astrophysical Journal |volume=572 |issue=2 |pages=735–745 |doi=10.1086/340432 |arxiv=astro-ph/0205040 |bibcode=2002ApJ...572..735S |issn=0004-637X}}

3C 171

|File:3C 171 cutout HST 05476 2l wfpc2 f702w pc sci.jpg

|2003{{Cite journal |last=Hardcastle |first=M. J. |date=2003-02-01 |title=Probing the extended emission-line region in 3C 171 with high-frequency radio polarimetry |journal=Monthly Notices of the Royal Astronomical Society |volume=339 |issue=2 |pages=360–366 |doi=10.1046/j.1365-8711.2003.06102.x |doi-access=free |arxiv=astro-ph/0209612 |bibcode=2003MNRAS.339..360H |issn=0035-8711}}

PKS 1932–46

|100

|2007{{Cite journal |last1=Inskip |first1=K. J. |last2=Tadhunter |first2=C. N. |last3=Dicken |first3=D. |last4=Holt |first4=J. |last5=Villar-Martín |first5=M. |last6=Morganti |first6=R. |date=2007-11-01 |title=PKS1932-46: a radio source in an interacting group? |journal=Monthly Notices of the Royal Astronomical Society |volume=382 |issue=1 |pages=95–108 |doi=10.1111/j.1365-2966.2007.12378.x |doi-access=free |arxiv=0708.2848 |bibcode=2007MNRAS.382...95I |issn=0035-8711}}

3C 79

|File:3C 79 MUSE.jpg

|2008

IC 2497

|File:Hannys voorwerp.jpg

|40

|2009

3C 48

|2009{{Cite journal |last1=Fu |first1=Hai |last2=Stockton |first2=Alan |date=2009-01-01 |title=Extended Emission-Line Regions: Remnants of Quasar Superwinds? |url=https://ui.adsabs.harvard.edu/abs/2009ApJ...690..953F |journal=The Astrophysical Journal |volume=690 |issue=1 |pages=953–973 |doi=10.1088/0004-637X/690/1/953 |arxiv=0809.1117 |bibcode=2009ApJ...690..953F |issn=0004-637X}}

Mrk 1014

|File:Mrk 1014 MUSE.jpg

|2009

3C 249.1

|2009

Ton 616

|2009

Ton 202

|2009

PKS 2251+11

|2009

Mrk 78

|File:Mrk 78 (50838249333).png

|16

|2012

SDSS J095559.88+395446.9

|File:SDSS J0955+3954.jpg

|10

|2012

SDSS J100507.88+283038.5

|File:SDSS J1005+2830 legacy surveys.jpg

|13

|2012

IC 2637

|11

|2012

NGC 3758

|File:NGC 3758 MUSE 2.jpg

|17

|2012

UGC 7342

|File:Heic1507e.jpg

|38

|2012

NGC 5252

|File:Heic1507f.jpg

|21

|2012

Mrk 273

|File:Mrk 273 Hubble.jpg

|19

|2012

Mrk 463

|File:Mrk 463 MUSE.jpg

|16

|2012

Teacup galaxy

|File:The Teacup Galaxy SDSS 1430.jpg

|18

|2012

SDSS J151004.01+074037.1

|File:Hs-2015-13-d-large web.jpg

|10

|2012

CGCG 077-117

(SDSS J152412.58+083241.2)

|File:CGCG 077-117 MUSE.jpg

|19

|2012

NGC 5972

|File:NGC 5972.jpg

|33

|2012

Mrk 1498

|File:Hs-2015-13-g-large web.jpg

|21

|2012

Mrk 883

|File:Mrk 883 legacy surveys.jpg

|37

|2012

UGC 11185

|File:Heic1507h.jpg

|11

|2012

SDSS J220141.64+115124.3

|File:Hs-2015-13-i-large web.jpg

|16

|2012

3C 305

|File:IC 1065 (3C 305) Chandra.jpg

|2012{{Cite journal |last1=Hardcastle |first1=M. J. |last2=Massaro |first2=F. |last3=Harris |first3=D. E. |last4=Baum |first4=S. A. |last5=Bianchi |first5=S. |last6=Chiaberge |first6=M. |last7=Morganti |first7=R. |last8=O'Dea |first8=C. P. |last9=Siemiginowska |first9=A. |date=2012-08-01 |title=The nature of the jet-driven outflow in the radio galaxy 3C 305 |journal=Monthly Notices of the Royal Astronomical Society |volume=424 |issue=3 |pages=1774–1789 |doi=10.1111/j.1365-2966.2012.21247.x |doi-access=free |arxiv=1205.0962 |bibcode=2012MNRAS.424.1774H |issn=0035-8711}}

3C 381

|38

|2013{{Cite journal |last1=Reynaldi |first1=V. |last2=Feinstein |first2=C. |date=2013-04-01 |title=Searching for evidence of jet-cloud interaction in radio galaxies. First results for 3C 381 |journal=Monthly Notices of the Royal Astronomical Society |volume=430 |issue=3 |pages=2221–2231 |doi=10.1093/mnras/stt042 |doi-access=free |arxiv=1301.2216 |bibcode=2013MNRAS.430.2221R |issn=0035-8711}}

NGC 7252

|2013{{Cite journal |last1=Schweizer |first1=François |last2=Seitzer |first2=Patrick |last3=Kelson |first3=Daniel D. |last4=Villanueva |first4=Edward V. |last5=Walth |first5=Gregory L. |date=2013-08-01 |title=The [O III] Nebula of the Merger Remnant NGC 7252: A Likely Faint Ionization Echo |url=https://ui.adsabs.harvard.edu/abs/2013ApJ...773..148S |journal=The Astrophysical Journal |volume=773 |issue=2 |pages=148 |doi=10.1088/0004-637X/773/2/148 |arxiv=1307.2233 |bibcode=2013ApJ...773..148S |issn=0004-637X}}

PGC 043234

|10

|2016{{Cite journal |last1=Prieto |first1=J. L. |last2=Krühler |first2=T. |last3=Anderson |first3=J. P. |last4=Galbany |first4=L. |last5=Kochanek |first5=C. S. |last6=Aquino |first6=E. |last7=Brown |first7=J. S. |last8=Dong |first8=Subo |last9=Förster |first9=F. |last10=Holoien |first10=T. W. -S. |last11=Kuncarayakti |first11=H. |last12=Maureira |first12=J. C. |last13=Rosales-Ortega |first13=F. F. |last14=Sánchez |first14=S. F. |last15=Shappee |first15=B. J. |date=2016-10-01 |title=MUSE Reveals a Recent Merger in the Post-starburst Host Galaxy of the TDE ASASSN-14li |journal=The Astrophysical Journal |volume=830 |issue=2 |pages=L32 |doi=10.3847/2041-8205/830/2/L32 |doi-access=free |arxiv=1609.00013 |bibcode=2016ApJ...830L..32P |issn=0004-637X}}

ShaSS 073

|File:An echo of light ShaSS 073, ShaSS 622, ShaSS 622-073 (cropped).jpg

|21

|2018{{Cite journal |last1=Merluzzi |first1=Paola |last2=Busarello |first2=Giovanni |last3=Dopita |first3=Michael A. |last4=Thomas |first4=Adam D. |last5=Haines |first5=Chris P. |last6=Grado |first6=Aniello |last7=Limatola |first7=Luca |last8=Mercurio |first8=Amata |date=2018-01-01 |title=An Interacting Galaxy Pair at the Origin of a Light Echo |journal=The Astrophysical Journal |volume=852 |issue=2 |pages=113 |doi=10.3847/1538-4357/aa9fff |doi-access=free |arxiv=1801.01005 |bibcode=2018ApJ...852..113M |issn=0004-637X}}

J023106−034513

|30

|2018

J083823+015012

|29

|2018

J090254+001116

|10

|2018

J091113+032604

|10

|2018

J092203−004443

|13

|2018

J155143+434758

|11

|2018

J162913+441442

|15

|2018

J220347+020443

|12

|2018

J220440+005232

|2018

J224027+004347

|2018

3C 17

|14.9

|2019{{Cite journal |last1=Balmaverde |first1=B. |last2=Capetti |first2=A. |last3=Marconi |first3=A. |last4=Venturi |first4=G. |last5=Chiaberge |first5=M. |last6=Baldi |first6=R. D. |last7=Baum |first7=S. |last8=Gilli |first8=R. |last9=Grandi |first9=P. |last10=Meyer |first10=E. |last11=Miley |first11=G. |last12=O'Dea |first12=C. |last13=Sparks |first13=W. |last14=Torresi |first14=E. |last15=Tremblay |first15=G. |date=2019-12-01 |title=The MURALES survey. II. Presentation of MUSE observations of 20 3C low-z radio galaxies and first results |url=https://ui.adsabs.harvard.edu/abs/2019A&A...632A.124B |journal=Astronomy and Astrophysics |volume=632 |pages=A124 |doi=10.1051/0004-6361/201935544 |arxiv=1903.10768 |bibcode=2019A&A...632A.124B |issn=0004-6361}}

3C 18

|24.8

|2019

3C 33

|11.2

|2019

3C 63

|38.0

|2019

3C 318.1 (NGC 5920)

|11.7

|2019

3C 327

|19.5

|2019

3C 353

|17.2

|2019

3C 386

|11.1

|2019

3C 403

|8.3

|2019

3C 424

|32.9

|2019

3C 442 (NGC 7236)

|3.8

|2019

3C 445

|18.5

|2019

3C 458

|File:3C 458 MUSE.jpg

|111.3

|2019

3C 459

|76.0

|2019

SDSS J002944.89+001011.1

|2019{{Cite journal |last1=Keel |first1=William C. |last2=Bennert |first2=Vardha N. |last3=Pancoast |first3=Anna |last4=Harris |first4=Chelsea E. |last5=Nierenberg |first5=Anna |last6=Chojnowski |first6=S. Drew |last7=Moiseev |first7=Alexei V. |last8=Oparin |first8=Dmitry V. |last9=Lintott |first9=Chris J. |last10=Schawinski |first10=Kevin |last11=Mitchell |first11=Graham |last12=Cornen |first12=Claude |date=2019-03-01 |title=AGN photoionization of gas in companion galaxies as a probe of AGN radiation in time and direction |journal=Monthly Notices of the Royal Astronomical Society |volume=483 |issue=4 |pages=4847–4865 |doi=10.1093/mnras/sty3332 |doi-access=free |arxiv=1711.09936 |bibcode=2019MNRAS.483.4847K |issn=0035-8711}}

SDSS J005754.03+012013.8

|File:SDSS J0057+0120.jpg

|2019

SDSS J083902.96+470756.3

|2019

Z 180–9

|2019

NGC 3341

|File:NGC 3341 MUSE.jpg

|2019

UGC 6081

|File:UGC 6081 legacy surveys.jpg

|2019

SDSS J120149.74-015327.5

|2019

SDSS J121418.25+293146.7

|File:SDSS J1214+2931 Hubble.jpg

|2019

Arp 239 (NGC 5278/NGC 5279)

|File:NGC 5278 79 Arp239 SDSS2.jpg

|2019

SDSS J135429.05+132757.2

|2019

Mrk 1172

|14

|2021{{Cite journal |last1=Lassen |first1=Augusto |last2=Riffel |first2=Rogério |last3=Chies-Santos |first3=Ana L. |last4=Johnston |first4=Evelyn |last5=Haeussler |first5=Boris |last6=Dutra |first6=Daniel R. |last7=Azevedo |first7=Gabriel M. |date=2021-01-01 |title=An Extended Emission Line Region around Mrk 1172 |url=https://ui.adsabs.harvard.edu/abs/2021IAUS..359..438L |journal=Galaxy Evolution and Feedback Across Different Environments. Proceedings of the International Astronomical Union |volume=359 |pages=438–440 |doi=10.1017/S1743921320004299|bibcode=2021IAUS..359..438L }}

NGC 235

|26

|2022{{Cite journal |last1=Keel |first1=William C. |last2=Moiseev |first2=Alexei |last3=Kozlova |first3=D. V. |last4=Ikhsanova |first4=A. I. |last5=Oparin |first5=D. V. |last6=Uklein |first6=R. I. |last7=Smirnova |first7=A. A. |last8=Eselevich |first8=M. V. |date=2022-03-01 |title=The TELPERION survey for distant [O III] clouds around luminous and hibernating AGN |journal=Monthly Notices of the Royal Astronomical Society |volume=510 |issue=3 |pages=4608–4625 |doi=10.1093/mnras/stab3656 |doi-access=free |arxiv=2112.07084 |bibcode=2022MNRAS.510.4608K |issn=0035-8711}}

NGC 5514

|75

|2022

3C 98

|2022{{Cite journal |last1=Balmaverde |first1=B. |last2=Capetti |first2=A. |last3=Baldi |first3=R. D. |last4=Baum |first4=S. |last5=Chiaberge |first5=M. |last6=Gilli |first6=R. |last7=Jimenez-Gallardo |first7=A. |last8=Marconi |first8=A. |last9=Massaro |first9=F. |last10=Meyer |first10=E. |last11=O'Dea |first11=C. |last12=Speranza |first12=G. |last13=Torresi |first13=E. |last14=Venturi |first14=G. |date=2022-06-01 |title=The MURALES survey. VI. Properties and origin of the extended line emission structures in radio galaxies |url=https://ui.adsabs.harvard.edu/abs/2022A&A...662A..23B |journal=Astronomy and Astrophysics |volume=662 |pages=A23 |doi=10.1051/0004-6361/202142823 |arxiv=2204.00528 |bibcode=2022A&A...662A..23B |issn=0004-6361}}

3C 135

|31.6

|2022

3C 180

|59.8

|2022

3C 196.1

|9.3

|2022

3C 198

|32.6

|2022

3C 227

|File:3C 227 MUSE.jpg

|46.1

|2022

3C 300

|17.2

|2022

2MASS J08001609+2928172

|2023{{Cite journal |last1=French |first1=K. Decker |last2=Earl |first2=Nicholas |last3=Novack |first3=Annemarie B. |last4=Pardasani |first4=Bhavya |last5=Pillai |first5=Vismaya R. |last6=Tripathi |first6=Akshat |last7=Verrico |first7=Margaret E. |date=2023-06-01 |title=Fading AGNs in Poststarburst Galaxies |journal=The Astrophysical Journal |volume=950 |issue=2 |pages=153 |doi=10.3847/1538-4357/acd249 |doi-access=free |bibcode=2023ApJ...950..153F |issn=0004-637X|arxiv=2304.10419 }}

Z 119–12

|2023

2MASX J13020015+2746579

|2023

2MASS J08152577+3720258

|2023

2MASX J09515536+0329006

|2023

UGC 5941

|2024{{Citation |last1=Keel |first1=William |title=The TELPERION survey for extended emission regions around AGN: a strongly-interacting and merging galaxy sample |date=2024-03-01 |url=https://ui.adsabs.harvard.edu/abs/2024arXiv240304898K |access-date=2024-03-29 |arxiv=2403.04898 |last2=Moiseev |first2=Alexei |last3=Uklein |first3=Roman |last4=Smirnova |first4=Aleksandrina}}

Markarian 950

|6.5

|2024{{Citation|last1=Wevers |first1=Thomas |last2=French |first2=K. Decker |date=June 2024 |title=Extended emission line regions in post-starburst galaxies hosting tidal disruption events |journal=The Astrophysical Journal |volume=969 |issue=1 |pages=L17 |doi=10.3847/2041-8213/ad5725 |doi-access=free |url=https://ui.adsabs.harvard.edu/abs/2024arXiv240602674W/abstract |arxiv=2406.02674 |bibcode=2024ApJ...969L..17W }}

J1000+0234

|File:J1000+0234 EELR.jpg

|>8.6

|2024{{Cite journal |last1=Solimano |first1=M. |title=A hidden AGN powering bright [O III] nebulae in a protocluster core at z=4.5 revealed by JWST |date=2024-07-17 |last2=González-López |first2=J. |last3=Aravena |first3=M. |last4=Pampliega |first4=B. Alcalde |last5=Assef |first5=R. J. |last6=Béthermin |first6=M. |last7=Boquien |first7=M. |last8=Bovino |first8=S. |last9=Casey |first9=C. M. |journal=A&A |arxiv=2407.13020}}

GSN 069

|File:GSN 069.jpg

|9.2

|2024{{Cite journal |last1=Wevers |first1=T. |last2=French |first2=K. D. |last3=Zabludoff |first3=A. I. |last4=Fischer |first4=T. C. |last5=Rowlands |first5=K. |last6=Guolo |first6=M. |last7=Dalla Barba |first7=B. |last8=Arcodia |first8=R. |last9=Berton |first9=M. |last10=Bian |first10=F. |last11=Linial |first11=I. |last12=Miniutti |first12=G. |last13=Pasham |first13=D. R. |date=2024-07-01 |title=X-Ray Quasi-periodic Eruptions and Tidal Disruption Events Prefer Similar Host Galaxies |journal=The Astrophysical Journal |volume=970 |issue=1 |pages=L23 |arxiv=2406.02678 |bibcode=2024ApJ...970L..23W |doi=10.3847/2041-8213/ad5f1b |doi-access=free |issn=0004-637X}}

RXJ1301

|File:RXJ1301.jpg

|2.8

|2024

eRO-QPE2

|File:ERO-QPE2.jpg

|4.6

|2024

Notes

References

Category:Emission nebulae

Category:Active galaxy types