GASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy
Koshy George, B. M. Poggianti, C. Bellhouse, M. Radovich, J. Fritz, R. Paladino, D. Bettoni, Y. Jaffé, A. Moretti, M. Gullieuszik, B. Vulcani, G. Fasano, C. S. Stalin, A. Subramaniam, S.N. Tandon
MMNRAS , 1– ?? (2018) Preprint 20 August 2019 Compiled using MNRAS L A TEX style file v3.0
GASP XVIII: Star formation quenching due to AGNfeedback in the central region of a jellyfish galaxy
K. George , , (cid:63) B. M. Poggianti , C. Bellhouse , M. Radovich , J. Fritz , R. Paladino ,D. Bettoni , Y. Jaff´e , A. Moretti , M. Gullieuszik , B. Vulcani , G. Fasano , C. S. Stalin ,A. Subramaniam , S.N. Tandon , Indian Institute of Astrophysics, Koramangala II Block, Bangalore, India Department of Physics, Christ University, Hosur Road, Bangalore 560029, India INAF-Astronomical Observatory of Padova, vicolo dell’Osservatorio 5 35122 Padova, Italy University of Birmingham School of Physics and Astronomy, Edgbaston, Birmingham, England Instituto de Radioastronomia y Astrofisica, UNAM, Campus Morelia, A.P. 3-72, C.P. 58089, Mexico Instituto Nazionale di Astrofisica - Istituto di Radioastronomia Via P. Gobetti, 101 40129 Bologna,Italy Instituto de F´ısicay Astronom´ıa, Universidad de Valpara´ıso, Gran Breta˜na 1111, Valpara´ıso, Chile Inter-University Center for Astronomy and Astrophysics, Pune, India
Accepted XXX. Received YYY; in original form ZZZ
ABSTRACT
We report evidence for star formation quenching in the central 8.6 kpc region ofthe jellyfish galaxy JO201 which hosts an active galactic nucleus, while undergoingstrong ram pressure stripping. The ultraviolet imaging data of the galaxy disk reveala region with reduced flux around the center of the galaxy and a horse shoe shapedregion with enhanced flux in the outer disk. The characterization of the ionizationregions based on emission line diagnostic diagrams shows that the region of reducedflux seen in the ultraviolet is within the AGN-dominated area. The CO J − map ofthe galaxy disk reveals a cavity in the central region. The image of the galaxy diskat redder wavelengths (9050-9250 ˚A) reveals the presence of a stellar bar. The starformation rate map of the galaxy disk shows that the star formation suppression in thecavity occurred in the last few 10 yr. We present several lines of evidence supportingthe scenario that suppression of star formation in the central region of the disk is mostlikely due to the feedback from the AGN. The observations reported here make JO201a unique case of AGN feedback and environmental effects suppressing star formationin a spiral galaxy. Key words: galaxies: clusters: intracluster medium, galaxies: star formation
The strength of ongoing/recent star formation in galaxies inthe local Universe is manifested in the observed distributionof galaxy colors and star formation rates. The star formingspiral galaxies populate a blue region and the S0/ellipticalgalaxies with little or no ongoing star formation popu-late the red region of the colour-magnitude distribution(Strateva et al. 2001; Baldry et al. 2004). Such a bimodalbehaviour is also observed from the star formation rate- stellar mass relation (Salim et al. 2007). The numberdensity of non-star forming L (cid:63) galaxies is observed toincrease from z ∼ to z ∼ (Bell et al. 2004; Faber et al. (cid:63) E-mail:[email protected] z = . and (Ilbert et al. 2013). This is due to the gradual or abruptcessation of star formation (known as quenching) in spiralgalaxies. Several secular processes such as AGN/stellarfeedback or the action of a stellar bar, and environmentalprocesses such as ram pressure stripping, major mergers,harassment, starvation, strangulation are invoked to explainthe star formation quenching in spiral galaxies (see Peng etal. (2015); Man, & Belli (2018)). The low mass star-forminggalaxies grow in mass by star formation, keeping thenumber density of star-forming galaxies of a given massquite constant by replacing quenched galaxies, as clearlyrequired in the continuity-type analysis (see Peng et al. © a r X i v : . [ a s t r o - ph . GA ] A ug K. George et al. (2010)).In the local Universe super massive black holes withmass > M (cid:12) at the center of galaxies are closely linked togalaxy formation and can also influence their evolution (Silk& Rees 1998; Magorrian et al. 1998; Gebhardt et al. 2000;Ferrarese & Merritt 2000) (see Kormendy & Ho (2013) fora review). This is possible since the black hole at the centeraccrete copious amounts of gas present in the disk makingthe galaxy go through an active galactic nucleus (AGN)phase (Bondi 1952; Gaspari et al. 2013; Tremblay et al.2016). The exact nature of the mechanism for gas accretionand the AGN phase are not fully understood, and variousmechanisms could be effective, including major mergers(Sanders et al. 1988), internal instabilities (Hopkins &Hernquist 2009) and enhanced activity due to ram-pressureby the intra-cluster medium (Poggianti et al. 2017a). Thekinetic and radiative energy from the accreting black hole(in the form of radiative heating, outflow and jet) can ionizethe cold gas near its vicinity, thus changing the dynamicalstate of the gas influencing the conditions necessary for starformation (Hopkins et al. 2006; Heckman & Best 2014).In extreme cases, the gas can be expelled from the galaxyhalting further star formation. This is hypothesized to beone of the channels for converting a star forming galaxyinto a non star forming, quiescent galaxy (Di Matteo et al.2005; Cheung et al. 2016). The same molecular hydrogengas responsible for star formation can also be accreted bythe black hole, hence star formation and AGN activity areusually tightly coupled at galaxy centers. The AGN thuscan have a negative impact with the dual role of suppressingboth star formation and gas accreting onto the black holeand this process is refereed to as AGN feedback (see Fabian(2012) for a recent review).Star formation in spiral galaxies can be suppressedalso by stellar bars (Masters et al. 2010, 2012; Cheung etal. 2013; Gavazzi et al. 2015; Hakobyan et al. 2016; James& Percival 2016; Spinoso et al. 2017; Khoperskov et al.2018; James & Percival 2018). The presence of a stellarbar in massive star forming galaxies has been argued tobe a dominant process in mass dependent star formationquenching and in regulating the redshift evolution ofspecific star formation rates for field galaxies (Gavazzi et al.2015). The likelihood for disk galaxies hosting stellar baris found to be anti-correlated with specific star formationrate regardless of stellar mass and the prominence of thebulge (Cheung et al. 2013). The presence of stellar barscan quench star formation in the central regions of galaxyby suppressing the star formation along the co-rotationradius of the bar (James & Percival 2018). The shock andshear generated within the galaxy due to the presence ofa bar can create turbulence preventing the molecular gasfrom collapse thereby inhibiting star formation (Reynaud& Downes 1998). The stellar bar in a galaxy can alsodynamically re-distribute the gas making the region closeto the bar devoid of fuel for further star formation (Combes& Gerin 1985).Star forming galaxies in the dense environments ofgalaxy clusters are subject to other forms of star formationquenching such as ram-pressure stripping, strangulation and harassment (Boselli & Gavazzi 2006). Ram-pressurestripping by the intra-cluster medium is an efficient way ofremoving gas from infalling galaxies (Gunn & Gott 1972).In some cases, stars can form in the stripped gas givingthe appearance of a jellyfish at optical or UV wavelengths(Cortese et al. 2007; Smith et al. 2010; Owers et al. 2012;Ebeling et al. 2014; Fumagalli et al. 2014; Poggianti etal. 2017b, 2019). There is observational evidence for AGNand ram-pressure stripping operating separately, quenchingstar formation in galaxies (Wylezalek & Zakamska 2016;Boselli & Gavazzi 2006), and recently a possible connectionbetween these two phenomena has been established (Pog-gianti et al. 2017a).We report unprecedented observations of a galaxy un-dergoing intense ram-pressure stripping and at the sametime experiencing star formation quenching in the centralregion. Our multi-wavelength dataset supports the notionthat the suppression of star formation is due to the pres-ence of an accreting black hole via feedback processes in thecentral 8.6 kpc. The galaxy JO201 is one of the most extreme cases ofram-pressure stripping in action and has been studied indetail for H α kinematics, presence of an AGN, moleculargas content and ongoing star formation (Bellhouse et al.2017; Poggianti et al. 2017a; Moretti et al. 2018; Georgeet al. 2018) as part of the GASP survey (Poggianti etal. 2017b). GASP (GAs Stripping Phenomena in galaxieswith MUSE) aims at investigating the gas removal processin a sample of 114 disk galaxies at redshifts 0.04-0.07,using the spatially resolved integral field unit spectrographMUSE (Poggianti et al. 2017b). This program focuseson galaxies in various stages of ram pressure strippingin clusters (Jaff´e et al. 2018; Vulcani et al. 2018c), frompre-stripping (undisturbed galaxies of a control sample),to initial stripping, peak stripping (Bellhouse et al. 2017;Gullieuszik et al. 2017; Poggianti et al. 2017b; Moretti et al.2018), and post- stripping (Fritz et al. 2017), and passive,and on a number of physical processes in groups andfilaments ranging from stripping to gas accretion, mergers,and cosmic web (Vulcani et al. 2017, 2018a,b,c).JO201 with a spectroscopic redshift z ∼ ∼
250 Mpc in the Abell85 galaxy cluster (Moretti et al. 2017) . The galaxy is ofspiral morphology with a total stellar mass ∼ × M (cid:12) (Bellhouse et al. 2017). The galaxy JO201 is fallinginto Abell 85 from the back along the line of sight with aslight inclination to the west, hosting intense star formationin the disk and in the stripped material due to the effectof ram-pressure stripping compressing the gas (Bellhouseet al. 2017; George et al. 2018). The galaxy’s high velocitywithin the cluster (3363.7 km/s with respect to the meanvelocity of Abell 85) and its proximity to the cluster centre α (J2000) = 00:41:30.325, δ (J2000) = - 09:15:45.96 The angular scale of 1” corresponds to 1.087 kpc at the Abell85 galaxy cluster rest frame. MNRAS , 1– ?? (2018) ASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy make it an extreme case of ram pressure stripping. Thepresence of an AGN in JO201 and in other five out of sevenjellyfish galaxies with long tails of stripped gas supportsthe idea that the AGN is triggered by intense ram-pressurestripping, which can potentially funnel gas into the centralparts of the galaxy (Poggianti et al. 2017a).The stellar populations in the galaxy disk of JO201consist of both younger and older populations, the relativecontributions of which are difficult to disentangle fromoptical observations. The UV flux is coming from the stellarphotospheres of young stars and directly traces the starformation over the past 100-200 Myr (Kennicutt & Evans2012), while the optical flux at redder wavelengths tracesmore evolved stellar populations. The H α emission on theother hand is due to star formation on timescales of 10-20Myr at most. The ongoing star formation in the disk ofthe jellyfish galaxy JO201 has been studied using UV andH α data in George et al. (2018). This paper builds on theresults presented in Poggianti et al. (2017a); George etal. (2018); Bellhouse et al. (2019) and focuses on the starformation properties in the central region surrounding theAGN in JO201, combining MUSE emission lines, opticalred continuum (9050-9250 ˚A), UVIT UV data and ALMACO map for the J − transition.We discuss the observations in section 2, and presentthe results in section 3, discussion in section 4. We summa-rize the key findings from the study in section 5. Through-out this paper we adopt a Salpeter 0.1-100 M (cid:12) initial massfunction, and a concordance Λ CDM cosmology with H =
70 km s − Mpc − , Ω M = . , Ω Λ = . . The galaxy JO201 was observed at optical wavelengths aspart of the WINGS and OmegaWINGS surveys (Fasano etal. 2006; Gullieuszik et al. 2015; Moretti et al. 2017) and withthe MUSE integral-field spectrograph on the VLT under theprogramme GASP with photometric conditions and imagequality of ∼ . (cid:48)(cid:48) ∼ H α emis-sion and UV imaging in the disk and in the tail (Bellhouseet al. 2017; George et al. 2018; Bellhouse et al. 2019).The emission line fluxes from the spectrum of eachMUSE spaxel are first corrected for stellar absorption usingthe best fitting combination of single stellar population mod-els to the MUSE spectra using the SINOPSIS code (Fritz etal. 2017). The emission lines are then fitted with modelscomprising single or double Gaussian profiles using kubeviz(Fossati et al. 2016) (see Bellhouse et al. (2017) for details).The galaxy has a larger line-of-sight component causing theemission lines in certain regions to be non-gaussian in naturewhich required a double component fit. The double compo- Figure 1.
Color composite image of J0201 made from combiningNUV (colored blue), H α (colored red) and [OIII] (colored green).The direction of the brightest cluster galaxy (BCG) is shown bythe arrow. Note the main disk of the galaxy with intense star for-mation (as seen in NUV and H α ) and the knots of star formationin the stripped material from the galaxy. The center of the galaxydisk and the region around are dominated by [OIII] emission dueto the accreting black hole at the center. nent fits are used in any given spaxel if the two componentswere detected to S/N > > λ mean =1481 ˚A, δλ =500 ˚A) and NUV (N242W filter, λ mean =2418 ˚A, δλ =785 ˚A) wavelengths using the UVIT in-strument on board the Indian multi-wavelength astronomysatellite ASTROSAT (Agrawal 2006; Tandon et al. 2017).The UVIT imaging yields a resolution of ∼ ∼ H β (4861.33 ˚A),[OIII] (4958.91 ˚A, 5006.84 ˚A), [FeVII] (6086.97 ˚A), [NII](6548.05 ˚A, 6583.45 ˚A), H α (6562.82 ˚A) and [SII] (6716.44˚A, 6730.81 ˚A) emission line flux maps of JO201 are usedin this study. We note that the NUV and FUV images ofthe JO201 galaxy disk show very similar features. The NUVimage has a better spatial resolution than the FUV hencewe use the NUV image to probe ongoing and recent starformation in the galaxy disk.JO201 was observed with ALMA in Cycle 5, usingBand 3 (100 GHz) and Band 6 (230 GHz) to observe theCO (J − ) and CO (J − ) transitions, respectively. A fulldescription of these observations and results is given in MNRAS , 1– ????
Color composite image of J0201 made from combiningNUV (colored blue), H α (colored red) and [OIII] (colored green).The direction of the brightest cluster galaxy (BCG) is shown bythe arrow. Note the main disk of the galaxy with intense star for-mation (as seen in NUV and H α ) and the knots of star formationin the stripped material from the galaxy. The center of the galaxydisk and the region around are dominated by [OIII] emission dueto the accreting black hole at the center. nent fits are used in any given spaxel if the two componentswere detected to S/N > > λ mean =1481 ˚A, δλ =500 ˚A) and NUV (N242W filter, λ mean =2418 ˚A, δλ =785 ˚A) wavelengths using the UVIT in-strument on board the Indian multi-wavelength astronomysatellite ASTROSAT (Agrawal 2006; Tandon et al. 2017).The UVIT imaging yields a resolution of ∼ ∼ H β (4861.33 ˚A),[OIII] (4958.91 ˚A, 5006.84 ˚A), [FeVII] (6086.97 ˚A), [NII](6548.05 ˚A, 6583.45 ˚A), H α (6562.82 ˚A) and [SII] (6716.44˚A, 6730.81 ˚A) emission line flux maps of JO201 are usedin this study. We note that the NUV and FUV images ofthe JO201 galaxy disk show very similar features. The NUVimage has a better spatial resolution than the FUV hencewe use the NUV image to probe ongoing and recent starformation in the galaxy disk.JO201 was observed with ALMA in Cycle 5, usingBand 3 (100 GHz) and Band 6 (230 GHz) to observe theCO (J − ) and CO (J − ) transitions, respectively. A fulldescription of these observations and results is given in MNRAS , 1– ???? (2018) K. George et al.
Moretti et al. (in preparation), here we only summarizethe most salient aspects of the data. Mosaics to cover thefull disk and the tails have been obtained. The ALMAconfigurations used provide a resolution of ∼
1” in bothbands, and allow to recover spatial scales up to 20 and 10 ”in band 3 and 6, respectively. The data have been calibratedusing the standard procedure (Pipeline-CASA51-P2-B) andimaged with the task clean using CASA version 5.4. TheRMS achieved in 20 km/s wide channels have been 0.5and 0.85 mJy/beam, for CO(1-0) and CO(2-1) respectively,using weighting Briggs with robust 0.5.
Fig 1 shows the color-composite (RGB) image of JO201made from combining the NUV image (blue), H α (red) and[OIII] (green) emission line maps. The galaxy disk and thestripped material show NUV and H α emission due to thepresence of ongoing star formation (see also Fig 4 . The west-ern region of the disk is the first contact point of the galaxywith the hot intra-cluster medium of the Abell 85 galaxycluster (Bellhouse et al. 2017; George et al. 2018). There theram-pressure compresses the gas and induces enhanced starformation, as demonstrated by the UV and H α enhancementalong a horse shoe shaped region to the west of the center.Moreover, there is a region surrounding the center of the diskthat is dominated by [OIII] emission which interestingly hasa reduced NUV and H α flux. The left most panel of Fig 2shows the reduced UV flux region surrounding a central re-gion with UV emission (we postpone the discussion on theother panel to later in this section). The contours createdfrom this NUV image are used in the rest of our analysisto identify star forming regions as well as the region withreduced star formation on the disk of JO201. We investi-gated whether the reduction in UV flux could be due todust extinction (the map is shown in Fig 3), and concludedthis is not the case. The A v map is created from the MUSEspectra using the Balmer decrement, assuming an intrinsicratio H α /H β = 3.1 typical of regions ionized purely by AGN(Osterbrock & Ferland 2006). In fact, the A v values are gen-erally low throughout the central region while extinction ishigher along the horse shoe shaped region seen in NUV.Emission line diagnostic diagrams (Baldwin et al. 1981)can be used to get clues on the mechanisms of gas ionizationas a function of the position within the galaxy. The H α , [SII],[OIII] and [NII] emission line flux maps for JO201 obtainedfrom the GASP MUSE data are used to create the line di-agnostic diagrams, based on which the contribution fromstar formation, composite (AGN+SF) and AGN are identi-fied as shown in Fig 4 (Bellhouse et al. (2019), Poggianti etal. (2017a)). We show in Fig 2 the regions corresponding toAGN (red), Composite (AGN+star formation, orange) andstar formation (blue) overlaid over the NUV image of thedisk of JO201.The presence of hot gas in the central region can bestudied from ionization lines of Fe. The [FeVII] 6086.97 ˚A , emission at the center of the galaxy is shown with cyan color contour of level 10 % of the peak value at the center inFig 2 (the emission line profile is displayed Radovich et al.(2019)). The [FeVII] emission region corresponds to the cen-tral bright NUV source. We note that the AGN contributesto and possibly dominates the UV flux at the galaxy cen-ter. Reduced star formation can be present at that locationbut this may not be revealed as the diagnostic diagrams aredominated by the AGN. The [FeVII] line can be due to theenergy output from the AGN at the center of the galaxy.The detection of this and higher ionization lines (e.g. [FeX]6374 ˚A) is generally explained (Mazzalay et al. 2010) withthe presence of hot gas ( T > K) heated either by theAGN continuum, or e.g. related to shocks triggered by ra-dio jets (Axon et al. 1998). This hot gas component maycontribute to the observed central UV emission via free-freeor free-bound radiation processes (see e.g. Mu˜noz Mar´ın etal. 2009). Furthermore, there is also a thin UV connectionbetween the central source and the galaxy disk, and in corre-spondence to this there is a significant decrease in UV flux.The most striking result from Fig 2 is that the NUVimage clearly shows a region around the center that has re-duced flux compared to the horse shoe shaped region on thewestern side of the disk that hosts instead intense star for-mation. The FUV image also shows a similar morphologyas shown in Fig. 4 of George et al. (2018). Further outward,there is intense UV emission coming from the northern, west-ern and southern regions of the disk where especially on thewestern side there appears to be enhanced star formation.As shown in Fig 2 (also see Fig 4), the classification basedon line diagnostic diagram demonstrates that the centralsource (diameter ∼ ∼ ∼ ∼ H α .Thus, the UV imaging clearly shows a cavity surround-ing the central AGN source and an outer disk region withenhanced star formation. We found that there is a factor of 2change in surface brightness between the outer disk and thecavity (excluding the central source that could be contam-inated by AGN) of JO201. This can in effect be translatedto the relative change in the star formation rate density be-tween the disk and the cavity of JO201. The star forma-tion rate is computed for a Salpeter initial mass functionfrom the FUV luminosity (L FUV ) (Kennicutt 1998) and us-ing the form of equation as described in Iglesias-P´aramo etal. (2006), adopted in Cortese et al. (2008) and shown inGeorge et al. (2018). Note that the formula is derived using
Starburst synthesis model (Leitherer et al. 1999) for solarmetallicity and a Salpeter 0.1-100 M (cid:12) initial mass function.The extinction correction is performed to the FUV lumi- MNRAS , 1– ?? (2018) ASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy − − − − − a r c s ec . . . . . . l og F [ − e r g/ s / c m / ˚A /a r c s ec ] − − − − − a r c s ec Star FormingAGNCompositeLiners
Figure 2.
JO201 galaxy disk NUV image (left panel) along with regions dominated by AGN, composite (AGN+SF) and star formation(right panel). The NUV image is showing enhanced emission at the center and along a horse shoe shaped region in the disk of the galaxy.The AGN dominated region is marked in red color. The composite (AGN+SF) region, marked in orange color, occupies a thin rim aroundthe AGN dominated region and inside the star forming region marked in blue color. The region occupied by LINER emission is markedin green. The [FeVII] 6086.97 ˚A emission line region at the center is shown by the cyan color contour.
Figure 3.
The V-band extinction map of the galaxy disk (A v in magnitude) derived from the Balmer decrement (H α /H β =3.1)based on MUSE observations. The region near the center wherewe are seeing reduced UV flux is not having a high extinctioncompared to the outer disk of the galaxy with enhanced UV flux.The green contour is taken from the NUV image shown in Fig 2. nosity using the method described in section 3.4 of Georgeet al. (2018). The integrated star formation rate density(SFR/Area) of the disk region (as defined by the UV contourshown in green in figures) is found to be 0.39 M (cid:12) /yr/kpc and for the cavity (as seen in Fig 2) to be 0.14 M (cid:12) /yr/kpc .There is a factor ∼ A sym (Whittle 1985),is based on the velocities measured at 10%, 50% and 90%of the cumulative flux percentiles ( v , v and v ). Weadopted the definition in Liu et al. (2013) (see also Radovichet al. (2019) for details): A sym = ( v − v )−( v − v ) v − v . In thisdefinition, positive/negative values of A sym indicate red/blueasymmetric lines. Note that the regions on the galaxy diskwith larger line asymmetry (redder/yellow regions) aremostly tracing the boundaries of the UV cavity, and couldbe tracing a larger spherical outflow or a bubble propagatinginto the medium from the AGN. This could possibly be thecause for the suppression of star formation in the UV cavity. MNRAS , 1– ????
The V-band extinction map of the galaxy disk (A v in magnitude) derived from the Balmer decrement (H α /H β =3.1)based on MUSE observations. The region near the center wherewe are seeing reduced UV flux is not having a high extinctioncompared to the outer disk of the galaxy with enhanced UV flux.The green contour is taken from the NUV image shown in Fig 2. nosity using the method described in section 3.4 of Georgeet al. (2018). The integrated star formation rate density(SFR/Area) of the disk region (as defined by the UV contourshown in green in figures) is found to be 0.39 M (cid:12) /yr/kpc and for the cavity (as seen in Fig 2) to be 0.14 M (cid:12) /yr/kpc .There is a factor ∼ A sym (Whittle 1985),is based on the velocities measured at 10%, 50% and 90%of the cumulative flux percentiles ( v , v and v ). Weadopted the definition in Liu et al. (2013) (see also Radovichet al. (2019) for details): A sym = ( v − v )−( v − v ) v − v . In thisdefinition, positive/negative values of A sym indicate red/blueasymmetric lines. Note that the regions on the galaxy diskwith larger line asymmetry (redder/yellow regions) aremostly tracing the boundaries of the UV cavity, and couldbe tracing a larger spherical outflow or a bubble propagatinginto the medium from the AGN. This could possibly be thecause for the suppression of star formation in the UV cavity. MNRAS , 1– ???? (2018) K. George et al. − . − . − . − . − . − .
25 0 .
00 0 .
25 0 . λ αλ − . − . − . . . . l og ( [ O III ] λ H β λ ) Kauffmann et al. 2003Kewley et al. 2001AGN/LINER − −
20 0arcsec − − − a r c s ec
10 kpc
Star FormingAGNCompositeLiners
Figure 4.
The BPT line-ratio diagnostics for JO201, mapped on top of the galaxy (right). The first (dominant) component of the doublecomponent fit from (Bellhouse et al. 2019) is plotted. The black lines separating different ionisation sources on the left panel come fromKauffmann et al. (2003), to separate star formation dominated regions from composite; Kewley et al. (2001), to separate composite fromAGN/LINER regions; and the AGN/LINER separator, taken from Sharp & Bland-Hawthorn (2010). The contours on the right panelcorrespond to the stellar FUV image contours. The distribution of the ionized gas in the galaxy disk shows an AGN region in centre ofthe galaxy surrounded by regions of ongoing star formation.
Figure 5.
The asymmetry map of the [OIII] emission line on thedisk of JO201 is shown with the NUV contours (green colour)overlaid. The regions with larger line asymmetry are tracing theboundary of the UV cavity, and could be tracing a spherical out-flow or a bubble propagating into the medium from the AGNwhich could be possibly suppressing the star formation in thecavity.
The CO J − transition intensity map made from theALMA observations of JO201 disk is shown in Fig 6. TheCO map (which traces the cold phase of molecular gas) isclearly showing a region with no detection around the cen-tral region of the galaxy. This observational result can beinterpreted in the context of AGN feedback; the energy fromthe AGN is sweeping out or ionising the medium around thecentral region of the galaxy leaving no molecular hydrogenbut instead ionized hydrogen as revealed from H α imagingobservations. The absence of molecular hydrogen leads to a Figure 6.
The CO J − transition intensity map of JO201 influx units of Jy/beam.Km/s. The green contour is taken from theNUV image shown in Fig 2. Note the cavity in CO map aroundthe central AGN. halt in ongoing star formation since the start of the AGNactivity (Cicone et al. 2014). The coincidence of the loca-tion of the cavity seen in the UV and CO data (with COcavity sitting inside the UV cavity) confirms our hypothe-sis that the energetic feedback from the AGN should havesuppressed the star formation in the central region of JO201disk. MNRAS , 1– ?? (2018) ASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy The JO201 image observed from 9050-9250 ˚A MUSE datareveals a stellar bar like feature oriented in the North-Southdirection (Fig 7). The stellar bar is of length ∼
13 kpc. Stel-lar bars are known to be sometimes able to suppress starformation in the disk of galaxies (Masters et al. 2010, 2012;Cheung et al. 2013; Gavazzi et al. 2015; James & Percival2016; Spinoso et al. 2017; Khoperskov et al. 2018; James &Percival 2018). The kinematic signature of the bar is usuallyprobed using the Calcium II triplet lines at 8498, 8542, and8662 ˚A. The Ca II triplet absorption lines trace evolved stel-lar populations (particularly due to the contribution fromstars in red giant branch (RGB) phase) (Jones et al. 1984;Armandroff & Zinn 1988). The MUSE data are strongly af-fected by sky emission at red wavelengths, and therefore inthe usual analysis of GASP galaxies the kinematic analy-sis is performed only up to the H α region. However, in thepresent case we have decided to analyze the redder region(from 8350 ˚A restframe), after having subtracted the skyemission using the ZAP code (Soto et al. 2016). In order todo this, we have also used the E-MILES stellar libraries ex-tended in the red region of the spectra (Vazdekis et al. 2010,2016). The stellar kinematic map of JO201 however is notshowing the presence of velocity structures expected fromthe presence of a stellar bar (see also Fig 10 of Bellhouse etal. (2017). This probably means that even though visible atred wavelength, the stellar bar is very faint and is not ableto alter significantly the kinematics. For this work we alsoperformed a two dimensional multi-component fit to the i band image of the galaxy. To derive the luminosity profilewe used the ellipse task in the isophote IRAF package (Je-drzejewski 1987). The resulting profile was then fitted with athree component model: a Sersic (S´ersic 1963), an exponen-tial disk (Freeman 1970) and a modified Ferrer law for thebar (Peng et al. 2010). Fig 8 presents the multi-component(Sersic,exponential,Ferrer) fit to the light profile and clearlyshows the presence of the stellar bar. The outer truncationradius of the fitted Ferrer function is 10.65” (11.57 kpc).Importantly, the stellar bar is visible only in the red-der wavelength (above 7000 ˚A) optical image of JO201 diskwhich should be tracing the flux from old stellar populations.The fact that the bar is only composed of old stars and doesnot host any recent star formation is also proven by the lackof UV emission tracing the bar. The stellar bar in JO201 islong and comparable to the bar length of similar mass diskgalaxies in the local Universe (Hoyle et al. 2011). The lengthof the bar further supports the notion that the bar is sev-eral Gyr old, as longer bars require a long timescale to form(Gadotti & de Souza 2006). Since the galaxy is on first infallinto the cluster, close to pericenter (see discussion in Bell-house et al. (2017)), and given the cluster crossing time, theold stellar bar appears to be a remnant of the secular evolu-tion prior infall into the cluster, rather than tidally inducedwithin the cluster environment ((cid:32)Lokas et al. 2016). We alsonote that the CO map also does not show any evidence ofbar, confirming there is no young bar present in the galaxy. Important clues about the origin of SF suppression in thecavity can be obtained from stellar ages considerations in
Figure 7.
The MUSE image of the disk of JO201 created inte-grating 9050-9250 ˚A wavelength slice. The stellar bar like featureis clearly seen in the disk of galaxy. NUV contours are overlaid(in green) to highlight the cavity with reduced UV flux. i [ m a g / a r c s e c ] Sersic, n=0.65ExponentialBar (Ferrer)Estimated profiledata0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0r [arcsec]0.500.250.000.250.50 i Figure 8.
The stellar profile fit to the MUSE i band image ofthe disk of JO201. The Sersic (blue), Exponential (green) andFerrer (cyan) function fit to the light distribution is shown. Sersicfunction is for the central bulge, exponential for the disk and theFerrer function is used to fit the stellar bar in JO201. the various regions. The spectrophotometric fitting codeSINOPSIS is used to derive the star formation rate (SFR)map of JO201 disk at different lookback times from theMUSE spectral data (SINOPSIS: Fritz et al. (2017)). (Bell-house et al. 2019) explains in detail the procedure used toderive the SFR for different age bins.Fig 9 presents the average SFR density maps createdfor stellar ages from 0.57-to-5.7 × yr (we call this asyoung age) and 1.0-to-5.7 × yr (we call this as old age).The SFR density map created for the younger stellar age isshowing a cavity similar to the one seen in UV and supportsthe hypothesis that there is a reduction in star formation in MNRAS , 1– ????
The stellar profile fit to the MUSE i band image ofthe disk of JO201. The Sersic (blue), Exponential (green) andFerrer (cyan) function fit to the light distribution is shown. Sersicfunction is for the central bulge, exponential for the disk and theFerrer function is used to fit the stellar bar in JO201. the various regions. The spectrophotometric fitting codeSINOPSIS is used to derive the star formation rate (SFR)map of JO201 disk at different lookback times from theMUSE spectral data (SINOPSIS: Fritz et al. (2017)). (Bell-house et al. 2019) explains in detail the procedure used toderive the SFR for different age bins.Fig 9 presents the average SFR density maps createdfor stellar ages from 0.57-to-5.7 × yr (we call this asyoung age) and 1.0-to-5.7 × yr (we call this as old age).The SFR density map created for the younger stellar age isshowing a cavity similar to the one seen in UV and supportsthe hypothesis that there is a reduction in star formation in MNRAS , 1– ???? (2018) K. George et al. the central region of JO201 disk compared to the outskirts.The SFR density map created for older ages on the contraryis showing a disk like feature with no cavity. The star for-mation rate density maps presented here demonstrate thatthe reduction in star formation happened in the last (5 − × yr.We note that our non-parametric approach to recon-struct the star formation as a function of the cosmic timeallows us, for spectra of the characteristics and quality suchas those we are using for this galaxy, to reach a coarse ageresolution which we represent with four age bins. These wereaccurately chosen by means of simulations (Fritz et al. 2007),in such a way that the difference of the spectral features aremaximized between different, consecutive, age bins. The rea-son for this choice is the impossibility of clearly distinguish-ing stellar populations of different ages. Hence, the SFR mapcalculated within each age bin is nothing more but an av-erage value of the stellar mass which was produced duringthat particular age bin, but whose precise age distributionwithin this same bin, we are not able to characterize in bet-ter detail. In Fig 9 we show the two age bins that are mostrelevant for our discussion. We stress that we are unable toidentify the precise time at which the star formation quench-ing occurred during the bin (0.57 − × yr, we can onlyassess that it happened at some point during this interval. The observed reduction in star formation around thecentral region of JO201 can in principle be due to theAGN or the stellar bar. Both the feedback from an AGNand the presence of a stellar bar are known to quench starformation in galaxies and it can be difficult to disentanglethe relative contribution of each process in suppressing thestar formation. We will now discuss in the following theobservational pieces of evidence, that can allow us to favorone hypothesis over the other.AGN feedback can inhibit star formation and therebyregulate galaxy evolution as demonstrated in observationsand simulations (Sanders et al. 1988; Springel et al. 2005;Di Matteo et al. 2005; Schawinski et al. 2007; Somerville etal. 2008; Hopkins et al. 2008; Schawinski et al. 2010; Wanget al. 2010; Liu et al. 2015; Cheung et al. 2016; Bing et al.2019). The outflows and energetic feedback from the AGNcan remove the gas from the disk of the galaxy or alterna-tively induce turbulence working against gas collapse. (alsosee Gabor, & Bournaud (2014), who based on simulationshave shown that AGN feedback has only a weak effect on gasdynamics of high-redshift disc galaxies.) The jet launchedfrom an accreting black hole influencing galaxy-scale starformation is demonstrated in recent simulations (Ishibashi& Fabian 2012; Gaibler et al. 2012; Ishibashi & Fabian 2014).The blast wave from the jet can produce an orthogonal bowshock which can push the gas outwards creating a cavityat the centre. The galaxy disk of JO201 is seen almost faceon (with a moderate inclination of 54 deg), the AGN is ofSeyfert 2 type and the outflow/jet can be tilted from theline of sight of observation. The small connection between the central source and the disk of the galaxy seen in the NUVimage can be then due to the effect of geometry in projec-tion. We note that the AGN+composite region in the galaxydisk (see Fig 2) is showing a slight elongation in the east andnorth west directions which also incidentally coincide withthe regions of reduced NUV flux in the horse-shoe area. Thiscan be due to the reduced star formation due to an increas-ing gas ionization in the direction of an outflow/jet launchedfrom the center of the galaxy disk. If we assume the energyfrom the AGN is dissipated into the surrounding medium atthe speed of light, the time taken by the AGN to create theobserved ionization region of size ∼ ∼ ∼ yr (Schawinski et al. 2015). Therefore it is possible thatthe star formation suppression is not the effect of a singleAGN episode, but due to the net effect of multiple phasesof the past AGN activity. There are observational evidencesfor fossil outflows due to a past strong AGN activity, butnow faded in local Universe galaxies (Fluetsch et al. 2019).The galaxy scale photoionized narrow line regiongenerated due to the AGN can then extend to several kpc.Therefore, it is possible for the AGN feedback to createthe size of ionizing region observed in the disk of JO201.We also point to Fig 5, where the [OIII] emission lineasymmetry map is showing indications of interaction ofa possible outflow from AGN with the boundaries of theUV cavity. The scenario of AGN feedback is much morestrongly demonstrated in the ALMA CO map in Fig 6,where the surrounding areas of the central AGN is devoidof CO (molecular hydrogen). This is also the region of highionisation temperature as traced by [FeVII] emission line(see Fig 2).The stellar bar in a galaxy can re-distribute the gasmaking the region close to the bar devoid of fuel for starformation (Combes & Gerin 1985). The natural expectationof such a scenario is that the region covered by the length ofthe stellar bar should be devoid of gas (in molecular, neutraland ionized form) as demonstrated based on a multiwave-length analysis of a face-on barred spiral galaxy Messier 95(George et al. 2019). First, we note that, as shown in Fig 7,the length of the bar exceeds the size of the cavity. Moreover,the cavity is not devoid of gas, as it is hosting ionized gasas evident from the MUSE emission line maps. This impliesthe presence of cold gas that had not been redistributed dueto a stellar bar prior to being ionized. Hence, the bar couldnot have suppressed star formation by totally sweeping thecavity of gas. We also note here that the Chandra archiveimage of JO201 shows no cavity at X-ray wavelengths whichsupports the scenario of AGN radiative feedback (Ichinoheet al. 2015).We conclude that the star formation suppression is theresult of recent AGN activity in the central region of JO201disk over a timescale of < × yr as revealed from the starformation history map of JO201 shown in Fig 9. In contrast,the stellar bar is much older, as testified by its very red colorand its length. Unfortunately, SINOPSIS does not providean exact dating of the bar formation, as any spectrophoto-metric code loses time resolution for old stellar populations. MNRAS , 1– ?? (2018) ASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy Figure 9.
Star formation rate density map of JO201 corresponding to two stellar age ranges, The SFR density for the average stellarages from .57-to-5.7 × yr (young age) is shown in left and from 1.0-to-5.7 × yr (old age) is shown in right panel. NUV contoursare overlaid (in green) to highlight the cavity with reduced UV flux. We choose same colour scaling for two panels for ease of comparison. It should be also noted that JO201 is freshly acquired intothe Abell 85 galaxy cluster and started undergoing ram-pressure stripping during the last ∼ We present a detailed study on the star formation progres-sion on the disk of jelly fish galaxy JO201. Based on a com-bined analysis of the ultraviolet imaging (UVIT), optical spectroscopy data (MUSE) and CO data (ALMA) we makethe following inferences. • The galaxy disk of JO201 is characterised by a ∼ • The Balmer decrement-based A v map of the galaxy diskconfirms that the cavity is not due to the effects of localizedextinction due to dust but instead is due to the suppressionof ongoing/recent star formation. • The CO (J − ) map clearly shows a region with no emis-sion in the central region of the galaxy and is situated insidethe cavity seen in the UV. This can be considered as an ev-idence for AGN feedback ionizing the molecular hydrogenand outflows sweeping the gas in its vicinity and therebyinhibiting star formation. • The BPT line diagnostics reveals an AGN emission re-gion that matches with the cavity seen in the ultraviolet.The high incidence of AGN at the center of jellyfish galaxieshas been suggested to be due to the effect of ram-pressurestripping (Poggianti et al. 2017a). At the same time, theram-pressure force enhances the star formation in the outerwestern side of the disk of JO201. Hence, in this galaxythere is a strong ongoing tussle between the AGN feedbackquenching the star formation in the central region and theram-pressure force (apart from stripping) which compressesthe gas in the galaxy disk enhancing star formation. • The [FeVII] emission in the central ∼ T > K) heatedeither by the AGN continuum or AGN-induced shocks. TheMUSE data reveals both a few kpc ongoing AGN outflowand regions of large [OIII] line asymmetry that trace theboundaries of the UV cavity and suggest the presence of alarger spherical outflow or bubble having propagated fromthe AGN.
MNRAS , 1– ????
MNRAS , 1– ???? (2018) K. George et al. • The redder (9050-9250 ˚A) optical image of the galaxyshows the presence of a stellar bar. The stellar bar is promi-nent at long wavelengths, is long (13 kpc of length) and old,and can be considered as the remnant of (probably secu-lar) evolution of the galaxy before being acquired into thecluster. The kinematic analysis performed on the red partof the spectrum, including Ca II triplet absorption spectrallines (which trace the the evolved stellar population) is un-able to detect the bar. • The star formation history map of JO201 disk demon-strates the existence of a star formation cavity in the last ∼ yr which is absent at older ages. This implies that thecavity seen in UV imaging data is a recent phenomenon.We conclude that the suppression of star formation ob-served in the central 8.6 kpc of JO201 is due to the effectsof AGN feedback happening after infall of the galaxy intothe cluster. The observations reported here present a uniqueexample of the combined role of AGN feedback and ram-pressure stripping in the quenching of star formation in spi-ral galaxies. ACKNOWLEDGEMENTS
We thank Anna Wolter and Myriam Gitti for discussionson X-ray imaging data of JO201. This publication uses thedata from the AstroSat mission of the Indian Space ResearchOrganisation (ISRO), archived at the Indian Space ScienceData Centre (ISSDC). Based on observations collected bythe European Organisation for Astronomical Research inthe Southern Hemisphere under ESO program 196.B-0578(MUSE). This paper makes use of the following ALMA data:ADS/JAO.ALMA
REFERENCES
Agrawal, P. C. 2006, Advances in Space Research, 38, 2989Armandroff, T. E., & Zinn, R. 1988, AJ, 96, 92Athanassoula, E., Machado, R. E. G., & Rodionov, S. A. 2013,MNRAS, 429, 1949Axon, D. J., Marconi, A., Capetti, A. et al. 1998, ApJ, 496, L75Baldry, I. K., Glazebrook, K., Brinkmann, J., et al. 2004, ApJ,600, 681Baldwin, J. A., Phillips, M. M., & Terlevich, R. 1981, PASP, 93,5Bell, E. F., Wolf, C., Meisenheimer, K., et al. 2004, ApJ, 608, 752Bellhouse, C., Jaff´e, Y. L., Hau, G. K. T., et al. 2017, ApJ, 844,49 Bellhouse, C., Jaff´e, Y. L., McGee, S. L., et al. 2019, MNRAS,485, 1157.Bing, L., Shi, Y., Chen, Y., et al. 2019, MNRAS, 482, 194.Bondi, H. 1952, MNRAS, 112, 195Boselli, A., & Gavazzi, G. 2006, PASP, 118, 517Cano-D´ıaz, M., Maiolino, R., Marconi, A., et al. 2012, A&A, 537,L8Caplar, N., Lilly, S. J., & Trakhtenbrot, B. 2015, ApJ, 811, 148Cheung, E., Athanassoula, E., Masters, K. L., et al. 2013, ApJ,779, 162Combes, F., & Gerin, M. 1985, A&A, 150, 327Cortese, L., Marcillac, D., Richard, J., et al. 2007, MNRAS, 376,157Cortese, L., Gavazzi, G., & Boselli, A. 2008, MNRAS, 390, 1282Chabrier, G. 2003, PASP, 115, 763Cheung, E., Bundy, K., Cappellari, M., et al. 2016, Nature, 533,504Cicone, C., Maiolino, R., Sturm, E., et al. 2014, A&A, 562, A21Di Matteo, T., Springel, V., & Hernquist, L. 2005, Nature, 433,604Ebeling, H., Stephenson, L. N., & Edge, A. C. 2014, ApJ, 781,L40Faber, S. M., Willmer, C. N. A., Wolf, C., et al. 2007, ApJ, 665,265Fabian, A. C. 2012, ARA&A, 50, 455Fasano, G., Marmo, C., Varela, J., et al. 2006, A&A, 445, 805Ferrarese, L., & Merritt, D. 2000, ApJ, 539, L9Fluetsch, A., Maiolino, R., Carniani, S., et al. 2019, MNRAS, 483,4586.Fossati, M., Fumagalli, M., Boselli, A., et al. 2016, MNRAS, 455,2028Freeman, K. C. 1970, ApJ, 160, 811.Fritz, J., Poggianti, B. M., Bettoni, D., et al. 2007, A&A, 470,137.Fritz, J., Moretti, A., Gullieuszik, M., et al. 2017, ApJ, 848, 132Fumagalli, M., Fossati, M., Hau, G. K. T., et al. 2014, MNRAS,445, 4335Gabor, J. M., & Bournaud, F. 2014, MNRAS, 441, 1615.Gadotti, D. A., & de Souza, R. E. 2006, ApJS, 163, 270Gaibler, V., Khochfar, S., Krause, M., & Silk, J. 2012, MNRAS,425, 438Gaspari, M., Ruszkowski, M., & Oh, S. P. 2013, MNRAS, 432,3401Gavazzi, G., Consolandi, G., Dotti, M., et al. 2015, A&A, 580,A116Gebhardt, K., Bender, R., Bower, G., et al. 2000, ApJ, 539, L13George, K., Poggianti, B. M., Gullieuszik, M., et al. 2018, MN-RAS, 479, 4126.George, K., Joseph, P., Mondal, C., et al. 2019, A&A, 621, L4.Gullieuszik, M., Poggianti, B., Fasano, G., et al. 2015, A&A, 581,A41Gullieuszik, M., Poggianti, B. M., Moretti, A., et al. 2017, ApJ,846, 27.Gunn, J. E., & Gott, J. R., III 1972, ApJ, 176, 1Hakobyan, A. A., Karapetyan, A. G., Barkhudaryan, L. V., et al.2016, MNRAS, 456, 2848.Heckman, T. M., & Best, P. N. 2014, ARA&A, 52, 589Hopkins, P. F., Hernquist, L., Cox, T. J., et al. 2006, ApJS, 163,1Hopkins, P. F., Hernquist, L., Cox, T. J., & Kereˇs, D. 2008, ApJS,175, 356-389Hopkins, P. F., & Hernquist, L. 2009, ApJ, 694, 599Hoyle, B., Masters, K. L., Nichol, R. C., et al. 2011, MNRAS,415, 3627.Ilbert, O., McCracken, H. J., Le F`evre, O., et al. 2013, A&A, 556,A55Ichinohe, Y., Werner, N., Simionescu, A., et al. 2015, MNRAS,448, 2971. MNRAS , 1– ?? (2018) ASP XVIII: Star formation quenching due to AGN feedback in the central region of a jellyfish galaxy Iglesias-P´aramo, J., Buat, V., Takeuchi, T. T., et al. 2006, ApJS,164, 38Ishibashi, W., & Fabian, A. C. 2012, MNRAS, 427, 2998Ishibashi, W., & Fabian, A. C. 2014, MNRAS, 441, 1474James, P. A., & Percival, S. M. 2016, MNRAS, 457, 917James, P. A., & Percival, S. M. 2018, MNRAS, 474, 3101Jaff´e, Y. L., Poggianti, B. M., Moretti, A., et al. 2018, MNRAS,476, 4753.Jedrzejewski, R. I. 1987, MNRAS, 226, 747Jones, J. E., Alloin, D. M., & Jones, B. J. T. 1984, ApJ, 283, 457Kauffmann, G., Heckman, T. M., Tremonti, C., et al. 2003, MN-RAS, 346, 1055Kewley, L. J., Dopita, M. A., Sutherland, R. S., Heisler, C. A., &Trevena, J. 2001, ApJ, 556, 121Kennicutt, R. C., Jr. 1998, ARA&A, 36, 189Kennicutt, R. C., & Evans, N. J. 2012, ARA&A, 50, 531Khoperskov, S., Haywood, M., Di Matteo, P., Lehnert, M. D., &Combes, F. 2018, A&A, 609, A60Kormendy, J., & Ho, L. C. 2013, ARA&A, 51, 511Leitherer, C., Schaerer, D., Goldader, J. D., et al. 1999, ApJS,123, 3Liu, G., Zakamska, N. L., Greene, J. E., et al. 2013, MNRAS, 436,2576.Liu, G., Arav, N., & Rupke, D. S. N. 2015, The AstrophysicalJournal Supplement Series, 221, 9.(cid:32)Lokas, E. L., Ebrov´a, I., del Pino, A., et al. 2016, ApJ, 826, 227.Magorrian, J., Tremaine, S., Richstone, D., et al. 1998, AJ, 115,2285Man, A., & Belli, S. 2018, Nature Astronomy, 2, 695.Masters, K. L., Mosleh, M., Romer, A. K., et al. 2010, MNRAS,405, 783Masters, K. L., Nichol, R. C., Haynes, M. P., et al. 2012, MNRAS,424, 2180.Mazzalay, X., Rodr´ıguez-Ardila, A. & Komossa, S. 2010, MNRAS,405, 1315Moretti, A., Gullieuszik, M., Poggianti, B., et al. 2017, A&A, 599,A81Moretti, A., Poggianti, B. M., Gullieuszik, M., et al. 2018a, MN-RAS, 475, 4055.Moretti, A., Paladino, R., Poggianti, B. M., et al. 2018b, MNRAS,480, 2508Mu˜noz Mar´ın, V. M., Storchi-Bergmann, T., Gonz´alez Delgado,R. M. et al. 2009, MNRAS, 399, 842Osterbrock, D. E., & Ferland, G. J. 2006, Astrophysics of gaseousnebulae and active galactic nuclei, 2nd. ed. by D.E. Oster-brock and G.J. Ferland. Sausalito, CA: University ScienceBooks, 2006,Owers, M. S., Couch, W. J., Nulsen, P. E. J., & Randall, S. W.2012, ApJ, 750, L23Peng, C. Y., Ho, L. C., Impey, C. D., & Rix, H.-W. 2010, AJ,139, 2097Peng, Y., Maiolino, R., & Cochrane, R. 2015, Nature, 521, 192Poggianti, B. M., Jaff´e, Y. L., Moretti, A., et al. 2017a, Nature,548, 304Poggianti, B. M., Moretti, A., Gullieuszik, M., et al. 2017b, ApJ,844, 48Poggianti, B. M., Gullieuszik, M., Tonnesen, S., et al. 2019, MN-RAS, 482, 4466.Radovich, M., Poggianti, B., Jaff´e, Y. L., et al. 2019, MNRAS,774.Rawle, T. D., Altieri, B., Egami, E., et al. 2014, MNRAS, 442,196Reynaud, D., & Downes, D. 1998, A&A, 337, 671Salim, S., Rich, R. M., Charlot, S., et al. 2007, ApJS, 173, 267Sanders, D. B., Soifer, B. T., Elias, J. H., Neugebauer, G., &Matthews, K. 1988, ApJ, 328, L35Sanders, D. B., Soifer, B. T., Elias, J. H., et al. 1988, ApJ, 325,74 Schawinski, K., Thomas, D., Sarzi, M., et al. 2007, MNRAS, 382,1415Schawinski, K., Dowlin, N., Thomas, D., Urry, C. M., & Edmond-son, E. 2010, ApJ, 714, L108Schawinski, K., Koss, M., Berney, S., & Sartori, L. F. 2015, MN-RAS, 451, 2517S´ersic, J. L. 1963, Boletin de la Asociacion Argentina de Astrono-mia La Plata Argentina, 6, 41Sharp, R. G., & Bland-Hawthorn, J. 2010, ApJ, 711, 818Silk, J., & Rees, M. J. 1998, A&A, 331, L1Smith, R. J., Lucey, J. R., Hammer, D., et al. 2010, MNRAS, 408,1417Somerville, R. S., Hopkins, P. F., Cox, T. J., Robertson, B. E., &Hernquist, L. 2008, MNRAS, 391, 481Soto, K. T., Lilly, S. J., Bacon, R., et al. 2016, MNRAS, 458,3210.Spinoso, D., Bonoli, S., Dotti, M., et al. 2017, MNRAS, 465, 3729Springel, V., Di Matteo, T., & Hernquist, L. 2005, ApJ, 620, L79Strateva, I., Ivezi´c, ˇZ., Knapp, G. R., et al. 2001, AJ, 122, 1861Tandon, S. N., Subramaniam, A., Girish, V., et al. 2017, AJ, 154,128Tremblay, G. R., Oonk, J. B. R., Combes, F., et al. 2016, Nature,534, 218Vazdekis, A., S´anchez-Bl´azquez, P., Falc´on-Barroso, J., et al.2010, MNRAS, 404, 1639.Vazdekis, A., Koleva, M., Ricciardelli, E., R¨ock, B., & Falc´on-Barroso, J. 2016, MNRAS, 463, 3409Vulcani, B., Moretti, A., Poggianti, B. M., et al. 2017, ApJ, 850,163.Vulcani, B., Poggianti, B. M., Moretti, A., et al. 2018a, ApJ, 852,94.Vulcani, B., Poggianti, B. M., Jaff´e, Y. L., et al. 2018b, MNRAS,480, 3152.Vulcani, B., Poggianti, B. M., Gullieuszik, M., et al. 2018c, ApJ,866, L25.Wang, J., Fabbiano, G., Risaliti, G., et al. 2010, ApJ, 719, L208.Whittle, M. 1985, MNRAS, 213, 1Wylezalek, D., & Zakamska, N. L. 2016, MNRAS, 461, 3724MNRAS , 1– ????