Star formation in AGNs at the hundred parsec scale using MIR high resolution images

0.52 MB·

by  Daniel Ruschel-Dutra

Mon.Not.R.Astron.Soc.000,1–9(2016) Printed19January2017 (MNLATEXstylefilev2.2)
Star formation in AGNs at the hundred parsec scale using
MIR high resolution images
7 Daniel Ruschel-Dutra1,2⋆, Jos´e Miguel Rodr´ıguez Espinosa1,
1
0 Omaira Gonz´alez Mart´ın1,3,4, Miriani Pastoriza2 and Rog´erio Riffel2
2
1Institutode Astrof´ısica de Canarias

n 2Departamento de Astronomia, Instituto de F´ısica da Universidade Federal do Rio Grande do Sul
a 3Departamento de Astrof´ısica, Universidad de La Laguna (ULL), 38205, La Laguna, Spain
J 4Centrode Radioastronom´ıa Astrof´ısica (CRyA-UNAM),3-72 (Xangari), 8701, Morelia, Mexico

8
1
19January2017

]
A
G ABSTRACT
. It has been well established in the past decades that the central black hole masses of
h
galaxies correlate with dynamical properties of their harbouring bulges. This notion
p
begs the question of whether there are causal connections between the AGN and
-
o its immediate vicinity in the host galaxy. In this paper we analyse the presence of
r circumnuclearstar formationin a sample of15 AGN using mid-infraredobservations.
t
s The data consist of a set of 11.3µm PAH emission and reference continuum images,
a takenwithgroundbasedtelescopes,withsub-arcsecondresolution.Bycomparingour
[
star formation estimates with AGN accretion rates, derived from X-ray luminosities,

1 weinvestigatethevalidityoftheoreticalpredictionsfortheAGN-starburstconnection.
v Our main results are: i) circumnuclear star formation is found, at distances as low as
8 tensofparsecsfromthenucleus,innearlyhalfofoursample(7/15);ii)starformation
4 luminositiesarecorrelatedwiththebolometricluminosityoftheAGN(LAGN)onlyfor
0 objects with LAGN > 1042 erg s−1; iii) low luminosity AGNs (LAGN < 1042 erg s−1)
5
seem to have starburst luminosities far greater than their bolometric luminosities.
0
. Key words: active galactic nuclei – interstellar medium – star formation.
1
0
7
1
:
v 1 INTRODUCTION the subject have shown the ubiquitous presence of star
i formation in Seyfert galaxies (Rodriguez Espinosa et al.
X The properties of the bulge of galaxies correlate with
1987;Gonz´alez-Delgado & P´erez1993;Cid Fernandes et al.
r the properties of their super massive black holes (SMBH, 2001;Kauffmann et al.2003;Riffel et al.2007;Davies et al.
a Kormendy & Richstone 1995, and references therein). Ar-
2007). There has also been a number of articles suggest-
guably the most widely known among these is the corre-
ingthatthefeedback from accretion ontotheSMBHwould
spondence between the mass (M•) of the SMBH and the quenchstarformationbyheatingtheavailablegas,deterring
velocity dispersion of stars in the bulge (σ), in short the
the gravitational collapse of molecular clouds (Silk & Rees
M•−σ relation (Ferrarese & Merritt 2000;Gebhardt et al. 1998; Vollmer & Davies 2013, and references therein). On
2000; Gu¨ltekin et al. 2009; McConnell & Ma 2013). Rela-
the other hand, the turbulence generated by supernova ex-
tionships such as these raise the question of whether or not
plosions could be responsible for the loss of angular mo-
thereisacausalconnectionbetweentheobservedproperties
mentum that ultimately leads the gas to the accretion
of the active nucleusand the host galaxy.
disk (Kawakatu & Wada 2008; Hopkins& Quataert 2010;
One of the possible physical links between the
Wutschiket al. 2013).
accretion-powered nuclear activity and its immediate vicin-
ity is the circumnuclear1 star formation, as this im- The MIR emission from polyciclic aromatic hydro-
plies a common mechanism for fuelling the growth of carbon (PAH) molecules has frequently been used as
both the SMBH and the stellar bulge. Early works on a tracer of star formation (e.g. Tielens 2008; Wu et al.
2009; Gallimore et al. 2010; Diamond-Stanic& Rieke 2010;
Ruschel-Dutraet al. 2014). These emission bands are pro-
⋆ E-mail:[email protected](AVR) duced when UV photons from young stars heat molecules
1 Hereand throughout this paper circumnuclear refersto scales totemperaturesoftheorderof1000K.Theenergyissubse-
oftheorderofhundredsofparsecsorless quently radiated by fluorescence through the many molec-
(cid:13)c 2016RAS
2 Daniel Ruschel-Dutra et al.
ular modes of oscillation and vibration. Since it is unlikely 3.0
that such large molecular species would survive the intense VISIRPAH2
radiation field from the active galactic nuclei (AGN, Voit VISIRPAH22
2.5 CanariCamPAH2
1992; Siebenmorgen et al. 2004), the analysis of their emis-
n CanariCamSi5
sion is virtually free from the degeneracy considerations sio
which are relevant for ionic lines. However, it has been ar- mis2.0
gued that the 11.3µm PAH band is an indicator of recent s
n
star formation (∼108 yrD´ıaz-Santos et al. 2010). tra1.5
This study aims at investigating the relationship be- d
e
tinweietns vthiceiniAtyG.NItaicstiovnitlyy annadturtahletorecseenatrchstafrorfoarmcaautisoanl maliz1.0
relation between these phenomena at the smallest possi- or
N
ble scales, e.g. at radii of tens of parsecs from the cen- 0.5
tral engine. Such regions are often enshrouded in dusty
clouds,favouringobservationsinwavelengthsotherthanthe
0.0
optical (Nenkovaet al. 2008; Ramos Almeida et al. 2011; 10.5 11.0 11.5 12.0 12.5
Sales et al. 2011; Gonz´alez-Mart´ın et al. 2013). At present, Wavelength(µm)
ground based mid infrared (MIR) observations with 10m
class telescopes offer the possibility of obtaining high res- Figure1. TransmissionprofilesoftheVISIR(red)andCanari-
olution images (∼ 0.4′′), at the same time avoiding most Cam(blue)filters.Solidanddashedlinesrepresentthe emission
of the extinction from the interstellar environment. There- andcontinuumfiltersrespectively,withrespecttotherestframe
wavelength.Thetransmissionintegralofeachfilterhasbeennor-
fore, here we analyse high spatial resolution PAH emission
malised.
images from two similar ground-based instruments, namely
the Very Large Telescope (VLT) Imager and Spectrometer
for mid Infrared (VISIR), and the CanariCam attached to parameters of the last paragraph. The similarity between
theGran Telescopio Canarias (GTC). the filters in CanariCam and VISIR allows for a consistent
The present paper is structured as follows: in §2 we combinedanalysis.Thespatialscalelimitappliedtothepro-
discuss the sample selection, observation strategy and re- prietary data is also respected by the VISIR observations.
duction process; our estimates for star formation rates, as Basic parameters for the complete sample of 15 AGNs are
well as the morphological features of the star forming re- shown in table 1.
gions are examined in §3; §4 examines how the empirical Our sample of nearby AGN is far from being complete
data compare with numerical models for the AGN-SBrela- both in volume and luminosity. A cross match between the
tion,§5containsadiscussion oftheresultsandfinallyin§6 AGNcatalogueofV´eron-Cetty& V´eron(2010)andtheEx-
we present our conclusions. tended12µm Galaxy Sample(Rushet al. 1993) returns44
sources with z < 0.03 and spectral classification of either
Seyfert or LINER. If we extrapolate on the region close to
the galactic equator left out from Rushet al. (1993) there
2 THE DATA should be ∼ 76 galaxies that fit the description. Conse-
quently, our sample represents close to 20% of the AGNs
2.1 Sample selection
with z<0.03 and F12 >0.2 Jy.
The target set for this study began with the selection of
4 galaxies, three of which were known to harbour AGNs,
2.2 Observations and data reduction
for observation with GTC/CanariCam, following a crite-
ria of spectral classification diversity. The chosen sources New proprietary data was acquired with CanariCam in the
were the Low Ionisation Nuclear Emission-Line Region filters PAH2 (λc = 11.26 µm) and Si5 (λc = 11.53 µm).
(LINER)NGC2146,theSeyfert1NGC931andtheSeyfert AdditionalarchivaldataconsistsofVISIRobservationswith
2’s NGC 1194 and NGC 2273, the former being classi- filtersPAH2(λc=11.26µm)andPAH2 2(λc =11.73µm).
fied as a Compton Thick source based on X-Ray data Thissetoffourfilters,apairforeachinstrument,waschosen
(Guainazzi et al. 2005). The selected sources also followed toyieldtheclosestpossibletocontinuumfreePAHemission
a technical limit of detectability for a reasonable integra- images. Thetransmission profiles of all thefilters employed
tion time of roughly 0.2 Jy in the 12µm filter of IRAS. in this work are shown in figure 1, where the transmission
This is also the lower limit in the Extended 12µm Galaxy coefficient wasnormalised sothat thetotalareaundereach
Sample(Rushet al.1993),althoughNGC2273violatesthe curveequals unity.
|b| > 25◦ restriction of this catalogue. Lastly, only galaxies Thefield ofviewfor CanariCam isarectangle measur-
with projected spatial resolutions on the order of hundreds ing 26′′ x 19′′, with a spatial sampling of 0.08′′/pixel. For
of parsecs were considered. VISIR, however, we used data from two distinct observa-
In order to add statistical weight to the present study, tion modes, with square fields of view of sides 32.5′′ and
12sourcesobservedwithVISIRattheVeryLargeTelescope 19.2′′. The corresponding pixel scales are 0.127′′/pixel and
(VLT) were added. The data for these targets were taken 0.075′′/pixel.
from the atlas published by Asmuset al. (2014). These ad- TheCanariCam dataacquisition followed thestandard
ditional galaxies consist of all the targets that are clearly recipe for MIR ground based observations, with thermal
detected in both thePAH2and Si-5filters, and respect the emission from the telescope and the atmosphere being re-
(cid:13)c 2016RAS,MNRAS000,1–9
Cicumnuclear star formation in AGNs 3
Table 1.Observationlog
PAH11.3 Si511.6
Target RA(J2000) DEC(J2000) Sp.Type Instrument DateObs. texp (s) DateObs. texp (s)
ESO005-G004 06h 05m 41.7s -86◦ 37’55.0” Sy2 VISIR 2010-11-22 900 2010-11-22 900
ESO138-G001 16h 51m 20.2s -59◦ 14’04.2” Sy2 VISIR 2008-03-14 600 2010-07-16 140
ESO383-G035 13h 35m 53.8s -34◦ 17’43.8” Sy1.2 VISIR 2004-04-14 180 2010-03-10 360
IC4329A 13h 49m 19.2s -30◦ 18’33.8” Sy1.2 VISIR 2010-03-12 180 2009-05-10 60
IC5063 20h 52m 02.3s -57◦ 04’07.6” Sy2 VISIR 2006-05-05 180 2005-06-10 200
Mrk1239 09h 52m 19.1s -01◦ 36’43.5” Sy1.5 VISIR 2005-01-28 1000 2006-03-12 600
NGC253 00h 47m 33.1s -25◦ 17’19.7” Sy2/SB VISIR 2004-12-01 1500 2004-12-01 1500
NGC931 02h 28m 14.4s +31◦ 18’41.4” Sy1.0 CanariCam 2013-09-05 278 2013-09-05 265
NGC1194 03h 03m 49.1s -01◦ 06’13.0” Sy2 CanariCam 2013-09-03 625 2013-09-04 199
NGC2146 06h 18m 37.7s +78◦ 21’25.3” LINER CanariCam 2013-09-04 139 2013-09-03 662
NGC2273 06h 50m 08.6s +60◦ 50’44.5” Sy2ct CanariCam 2013-09-08 625 2013-09-06 662
NGC5128 13h 25m 27.6s -43◦ 01’08.8” Sy2 VISIR 2006-04-09 180 2006-03-15 600
NGC5506 14h 13m 14.9s -03◦ 12’27.2” Sy1.9 VISIR 2010-02-23 180 2006-06-06 600
NGC5995 15h 48m 24.9s -13◦ 45’28.0” Sy2/SB VISIR 2010-07-26 1000 2010-07-26 1000
NGC6240 16h 52m 58.8s +02◦ 24’03.6” Sy2/LINER VISIR 2005-04-19 1800 2005-04-19 1800
NGC7469 23h 03m 15.6s +08◦ 52’25.3” Sy1.2 VISIR 2006-07-12 180 2006-06-15 600
moved by the chopping/nodding technique. The same ap- thereisconsiderableoverlapbetweentheemissionandrefer-
plies to the archival VISIR data. In the latter case, some encefilters in both instruments.This is particularly truein
ofthenodframes whichhadintensedetectorartefacts were the case of CanariCam, where the continuum reference fil-
classified by visual inspection and discarded, resulting in a terhasnearly60%ofitstransmissioncurveincommonwith
total exposure time slightly lower than the one originally the PAH2 filter. Furthermore, the distance between the fil-
intended. ters,althoughsmallincomparisontotheirFWHM,arelarge
The reduction process for the CanariCam data em- enoughfordifferencesincontinuumlevelstobecomenotice-
ployed the RedCan pipeline (Gonz´alez-Mart´ın et al. 2013), able.Therefore,asimplesubtractionofthecontinuumlevel,
withtheadditionofarecentlydevelopedalgorithmtoregis- asprobedbythereferencefilter,cannotleadtoanaccurate
terthecentroidinasequenceofnodimagesandrealign the estimate of thePAH emission.
exposures. This allowed us to obtain nearly diffraction lim- Analysing tens of AGNs with already published high
itedimagesfrom whatwasotherwiseaseeinglimitedstack. resolution MIR spectra (e.g. Ruschel-Dutraet al. 2014;
Standardstars,observednotmorethananhourapartfrom Sales et al. 2014; Gonz´alez-Mart´ın et al. 2013; Esquej et al.
thescienceexposures,wereusedtofluxcalibratetheimages. 2013), one findsthat low resolution spectra, taken with the
The VISIR images were used as published in Asmus et al. Infrared Spectrometer (IRS) aboard the Spitzer space tele-
(2014), thus we refer the reader to that paper for details scope, show an underlying continuum that is very similar
about thereduction process. to that of the high resolution spectra. The reason for this
agreement lies inthedominantrole ofpowerlaw andwarm
dustemissionassociatedwiththeAGN,plusthesilicateab-
3 IMAGING ANALYSIS sorption bands at 9.7 µm and 16.8 µm. The later, even if
not directly linked to the active nucleus, imprints its effect
Inthissectionwediscussthemethodologyandresultsfrom
on the line of sight that leads to theAGN.
theanalysis of theMIRimages. At first theproblem of iso-
In order to produce a model of the continuum we ex-
latingthelocationofPAHemissionisinvestigated,followed
amined the Spitzer/IRS spectra of our targets, available at
by a description of the new observations with CanariCam. theSpitzer archive2,withthespectralanalysistoolpahfit
Finally photometric measurements are discussed.
(Smith et al. 2007). By fitting the spectrum as a combina-
tion of continuum emission, silicate absorption, and emis-
3.1 PAH emission maps sion from molecules and ions, the code is able to return a
sophisticated estimate for the continuum shape. Since we
The simplest approach to the problem of isolating the are studying galaxies, the redshift of the spectrum had to
11.3 µm PAH emission would beto producemaps, employ- betakenintoconsiderationwhenproducingthemodel.The
ingamethodtocompensateforthedifferentcontinuumlev- readershouldkeepinmindthatSpitzer/IRShasaslitwidth
els in both filters. The objective here is not yet to reach an of 3.6′′, and therefore is sampling a much larger region of
accurate measurement of PAH emission, but rather to lo- thegalaxythangroundbasedobservations.Neverthelessthe
cateexcessesinthePAHsamplingfilterwithrespecttothe dominanceofthenucleusoverthehostgalaxymakesitpos-
expected continuum level. sibleto obtain afair approximation of thecontinuumusing
ThewidthofMIRfilterstendstobeconsiderablylarger low resolution spectroscopy.
than their counterparts in the optical range, close to half a We use this continuum emission as an estimate of the
micrometer, as can be seen in figure 1. With central wave-
lengthsseparatedbydistancesthatmaybesmallerthanthe
filter’sfullwidthathalfmaximum(FWHM),itisclearthat 2 http://sha.ipac.caltech.edu/applications/Spitzer/SHA/
(cid:13)c 2016RAS,MNRAS000,1–9
4 Daniel Ruschel-Dutra et al.
slope of the continuum under the PAH feature. Assuming
ESO138-G001 IC4329A
that the same continuum shape holds throughout the im-
age’s field of view, we can then produce a qualitative map 1 1 10
)
ofthedeviationfromthenullhypothesis,whichishavingno ec Jy
PAHemissionatall.Inotherwords,wearebuildingaquali- s 0 0 5 m
c
tativemapofPAH“excess”.Theoperationcanbedescribed ar (
ν
by theequation −1 −1 0 F
−1 0 1 −1 0 1
−5
F1Cdλ Mrk1239 NGC0253
E =(cid:12)(cid:12)(cid:12)I1−I2RR F2Cdλ(cid:12)(cid:12)(cid:12) (1) 1 1 10 y)
where E is the differen(cid:12)ce from the nul(cid:12)l hypothesis, In is csec 0 0 5 mJ
the image in the n filter, Fn is the normalised transmis- ar −1 −1 (ν
sionfunctionofthenfilterandC isthefunctiondescribing 0 F
thesemi-empirical continuum.This model is limited bythe
−1 0 1 −1 0 1
possibility of spatial variations of the continuum function, −5
which could also produce an “excess” as the one described NGC5128 NGC5506
above.Nevertheless,thereis currentlynobetteralternative 1 1 10
to infer the continuumslope. We would also like to empha- y)
sise that thecontinuumfunction is independentlymodelled ec J
s 0 0 5 m
for each target according to its Spitzer/IRS spectrum and rc (
a
redshift. −1 −1 0 Fν
Employing this method we conclude that from the 15
galaxies in our sample only four show PAH emission in the −1 0 1 −1 0 1 −5
image subtraction. Of these, only NGC 253 displays an ex- NGC7469 arcsec
tended structure, with all the other galaxies appearing as
1
unresolved sources. The PAH emission maps that resulted
from the continuum subtraction are displayed in figure 2, ec
s 0
for the spatially unresolved and resolved sources. Notably, c
r
a
ascanbeseenin table1,theimageson eachfilterhavenot
−1
been taken in the same observing night for all the targets.
Therefore, the point spread function (PSF) of the images −1 0 1
arenotnaturallymatched.Perhapsthemostnotablecaseof
arcsec
PSFmismatcharetheobservationsofMrk1239,whichshow
lobesextendingbeyondtheFWHMofthecentralsource.We
thusrefrainfromassertionsonmorphologyfeaturesthatare Figure 2. Continuum subtracted 11.3µm PAH images for the
below the wider of the two PSFs. Considering this caveat, galaxies classified as displaying resolved or unresolved emission.
Theellipsesintheupperrightcornerofeachimagerepresentthe
only NGC 253 can be safely classified as having extended
FWHMofthestandardstar.
PAH emission.
Apart from the four galaxies with larger fluxes on the
PAH images, we find two sources, namely NGC 5128 and
dental with H II regions already identified in the literature
NGC7469,whichhavefluxesinthePAHimageslowerthan
(Forbes et al. 2000; Lira et al. 2007).
the expected from the inferred continuum slope. This ef-
fect can bedue toan overestimate of this slope, or to some
of the emission from the molecular band “leaking” into the
3.2 Proprietary CanariCam images
reference filter. This last issue is further discussed in sec-
tion 4 and in the appendix, where we present our method SincesomeofourtargetsarehavingtheirMIRimagespub-
for dealing with the effects of redshift in the relative fluxes lished for the first time in this paper, we take this oppor-
between the filters. Additionaly, NGC 5506 shows a small, tunity to examine their images in more depth. Four galax-
almost unresolved, PAH “excess” and a region where the ies were observed with CanariCam: NGC 931, NGC 1194,
continuum image is more intense than expected, leading to NGC 2146 and NGC 2273. The images in the filters PAH2
slightly negative values in figure 2. Since the net result is -11.3µm andSi5-11.6µm forthefourgalaxies areshown
closetozero,weconservativelyexcludethisgalaxyfromthe in figure 3. For display purposes, the images of NGC 2146
list of positive detections. havebeenconvolvedwithaGaussianwithσ ofonepixel,in
It is important to keep in mind the projected scale of order toemphasise thelarge scale structure.
these images, and consequently the maximum radius of an Atthisdepthandspatialresolution,thegalaxieswhich
unresolved source. ForMrk 1239, thefarthest galaxy in fig- harbouranAGNappearaspoint-likesourcesinbothfilters,
ure 2, the PAH emitting region is at most 400 pc away includingtherelativelycloseNGC2273(z=0.006).Incon-
from the central engine, and for the nearest target, namely trast, NGC 2146 shows diffuse emission in the form of a
NGC 253, the same region is no further than 19 pc. In the band extendingfrom southeast to northwest. The direction
case of NGC 253, structures seen in emission are coinci- ofthisstructurecoincides with thedensedust laneidentifi-
(cid:13)c 2016RAS,MNRAS000,1–9
Cicumnuclear star formation in AGNs 5
3.3 Artefacts in CanariCam imaging
NGC931-PAH2-11.3 NGC931-Si5-11.6
8.4
In some of the images, particularly in the case of NGC 931
1
7.0y) andNGC2273,onecanclearlyseeapatternofthreebright
sec 0 5.6mJ spots circling the central object. Since the same pattern is
rc 4.2( alsovisibleinthestandardstarimages theyarealmost cer-
a
ν
−1 2.8F tainly not real. This pattern is a combination of several
1.4 effects: the hexagonal shape of GTC’s mirror and its seg-
0.0 ments; a small difference in phase between segments; and
NGC1194-PAH2-11.3 NGC1194-Si5-11.6 1.8 small guiding errors. The effect is not apparent in the im-
1 1.5 ages of NGC 1194 dueto its lower signal to noise ratio.
)
sec 0 1.2mJy telesTcohpeelgaustidoifngthaenadbtohveewmaeyntCioanneadriCissaumesreiscorredlastethdetdoatthae.
c 0.9
ar ( Eachsavesetistheresultofnearlysixsecondsofchopcycles,
−1 0.6Fν which are stored in a buffer before being written as a file.
0.3 Thesourcepositionbetweenframesvariesasmuchas∼0.8′′
0.0 peak-to-peak, and in fact it is apparent by the structures
NGC2146-PAH2-11.3 NGC2146-Si5-11.6 1.2 seen in each of the savesets that such variations also occur
1 betweenchopcycles.Registeredstackingoftheaccumulated
1.0)
y chopframescaneasilysolvetheproblemofimagemovement
ec 0.8J
s 0 m betweensavesets,aslongasthetargetsarebrightenoughto
arc 0.6( be detected in each frame. Nevertheless, movement within
−1 0.4Fν eachsavesetrequiresaguidingcorrectionfrequencyatleast
0.2 equalto the choppingfrequency.
0.0 Unlike the diffraction features, which are directly re-
NGC2273-PAH2-11.3 NGC2273-Si5-11.6 3.0 lated to the relative position between the detector and the
1 2.5) primary mirror, the guiding artefacts are stochastic in na-
ec 2.0Jy ture.Thusitisimpossibletoeliminatethembysimplecom-
s 0 m parison with the standard star. These effects, while poten-
rc 1.5(
a tiallyharmfultothemorphologicalanalysis,areinnowway
−1 1.0Fν detrimentaltothephotometry,providedthattheapertures
0.5 includethe stray light.
0.0
−1 0 1 −1 0 1
arcsec arcsec
3.4 Photometry
Figure3. ImagesacquiredwithCanariCam.Withtheexception Fluxeswereobtainedfromtheimagesthroughaperturepho-
ofNGC2146,forwhichnoclearnucleuscanbeidentified,allthe tometry, considering virtual pupils with radii equal to the
othergalaxiesinthissetappearaspointlikesources.Inorderto FWHM of the standard star employed in the flux calibra-
highlighttheextendedstructureofNGC2146itsimagehasbeen tion.Thebackgroundlevelswereevaluatedfromanannulus
convoluted by a Gaussian. The faint ring like structures seen in with width equal to the aperture’s radius, separated from
NGC 931 and NGC 2273 are very likely instrumental artefacts
thelatterbyhalfitsradius.Allthesumswereperformedby
(see text). In all figures North is up, East is left, and the ellipse
our own routines which include treatment of partial pixels.
inthelowerrightrepresentstheFWHMofthestandardstar.
Photometric data are displayed in table 2.
Signal to noise ratio estimates for MIR images have a
few differences from their optical counterparts. The consid-
eration that atmospheric emission follows a Poisson distri-
bution does not hold for a chop frequency of a few tens
of milliseconds. The reason is that at such short intervals
ableinopticalandnearinfrared imagesofthisgalaxy(e.g., there is a significant correlation between background levels
Martini et al. 2003). Although this galaxy is classified as a insubsequentframes.Moreover,thebackgroundlevelisalso
LINER, no clear nucleus could be identified, and therefore a function of the emission from the telescope itself, making
it was left out of the AGN sample. We conclude that this itevenmoretimedependent.Wechosetoestimatethenoise
galaxy probably has a LINER-like emission attributable to levelsfrom thestandarddeviation ofthebackgroundin the
sourcesotherthantheSMBHaccretiondisk,suchasshocks annulus.
orevolvedstars(Filippenko & Halpern1984;Stasiska et al. Infigures4and5wepresentthephotometricpointsfor
2008). the15galaxiesinthesample,plottedalongarchivalspectra
Onlyoneofthesefoursourcesshowsanappreciabledif- from Spitzer/IRS. Since the spatial resolution of Spitzer is
ference in flux between filters, namely the Seyfert 2 (Sy2) muchlowerthanthatofthedataofCanariCam andVISIR,
NGC 1194. The similarity in filter fluxes is an expected re- the flux in the nuclear extractions of the later is naturally
sult, since thetransmission curvesoverlap and thedistance smaller.Wealsoshowinthesefiguresthecontinuuminferred
between central wavelengths is comparable to the FWHM from thespectral fittingwith pahfit.
of the emission band we are tryingto probe. The photometry of all the other galaxies seems to be
(cid:13)c 2016RAS,MNRAS000,1–9
6 Daniel Ruschel-Dutra et al.
Table 2.Photometricfluxes
ID Target z L2−10keV Aperture fP1AH fR1EF LAGN LPAH LSB SFR
(logergs−1) (parsec) (mJy) (mJy) (logergs−1) (1040 ergs−1) (logergs−1) (M⊙ yr−1)
1 ESO005-G004 0.006 41.92a 128.7 19±4 24±5 42.94 13+28 43.3+0.5 0.3+0.7
−9 −0.5 −0.2
2 ESO138-G001 0.009 42.52b 191.0 665±11 640±14 43.65 64+137 43.9+0.5 1.6+3.4
−43 −0.5 −1.1
3 ESO383-G035 0.008 42.41c 164.0 305±8 301±19 43.52 < 4 < 42.8 < 0.1
4 IC4329A 0.016 43.70d,e 332.2 973±12 905±25 45.13 855+1849 45.1+0.5 21+46
−585 −0.5 −15
5 IC5063 0.011 42.94f 234.6 616±14 809±17 44.17 < 19 < 43.4 < 0.5
6 Mrk1239 0.020 40.82g 413.2 602±9 522±8 41.70 < 302 < 44.6 < 7.5
7 NGC0253 0.001 40.00h 18.7 1768±97 1561±114 40.83 7.8+16.8 43.0+0.5 0.2+0.4
−5.3 −0.5 −0.1
8 NGC0931 0.016 43.28i 338.5 210±10 217±12 44.60 < 540 < 44.9 < 13.5
9 NGC1194 0.014 42.64j 282.4 176±17 167±7 43.80 < 211 < 44.5 < 5.3
10 NGC2273 0.006 42.23k 128.7 111±5 106±6 43.30 25+55 43.5+0.5 0.6+1.4
−17 −0.5 −0.4
11 NGC5128 0.002 42.31l 37.4 823±17 991±13 43.40 1.3+2.8 42.3+0.5 0.03+0.07
−0.9 −0.5 −0.02
12 NGC5506 0.006 43.01c 122.5 704±15 839±13 44.26 13+28 43.2+0.5 0.3+0.7
−9 −0.5 −0.2
13 NGC5995 0.025 43.53m 521.2 290±3 291±5 44.92 < 23 < 43.5 < 0.6
14 NGC6240 0.024 44.26n 504.6 152±15 185±12 45.87 < 116 < 44.2 < 2.9
15 NGC7469 0.016 43.02o 330.1 393±11 479±9 44.27 < 68 < 44.0 < 1.7
1 Thesefluxdensitiesarethedirectresultofaperturephotometryoverthemonochromaticimages,withoutanyoftheproceduresfor
continuum subtractionorredshiftcompensationdiscussedinthetext. ReferencesfortheX-rayluminosities:a Winter etal.(2009);
b Piconcellietal.(2011);c Nandraetal.(2007);d Shinozaki etal.(2006);e Bianchietal.(2009);f Marinuccietal.(2012);
g Corraletal.(2011);h Mu¨ller-Sa´nchezetal.(2010);i Uedaetal.(2011);j Greenhilletal.(2008);k Awakietal.(2009);l Shuetal.
(2011);m Uedaetal.(2005);n Gonz´alez-Mart´ınetal.(2006);o Gonz´alez-Mart´ın&Vaughan(2012);p Brightman&Nandra(2011);
in good agreement with the Spitzer/IRS spectra, in the imagesubtractionresultedinpositivedetectionsofPAHand
sense that the photometric points are at most equal to the vice-versa.
spectroscopicflux.Interestingly,galaxiesshowingprominent Once known, the total flux emitted in the 11.3 µm
10.5µm [Siv] emission are the ones that show better agree- PAH flux can be used in onjunction with empirical rela-
ment between nuclear photometry and host galaxy spec- tions for the SFR. Although this molecular feature has a
trum, probably due to the prevalence of the central source. less stringent correlation with SFR than the emission band
Whereas in galaxies with weak [Siv] emission the AGN is at 8.6 µm (Diamond-Stanic& Rieke 2010), the features at
correspondingly less dominant in the low spatial resolution 8.6µmappeartobeobservationallysuppressedinthevicin-
spectrum.TargetsshowingverystrongPAHemissioninthe ity of the AGN, while the 11.3 µm seems to be less af-
Spitzer/IRS spectra tend to have nuclear fluxes well below fected(Alonso-Herrero et al.2011).Thatapparentsuppres-
those of the host galaxy, and even below pahfit’s estimate sionshouldnotbeconfusedwiththephysicaldestructionof
for the continuum. PAH molecules, but rather the dilution of PAH emission in
the intense continuum emission from the AGN (Sales et al.
2010; Alonso-Herrero et al. 2014).
Aspreviouslydiscussedintheintroduction,the11.3µm
4 STAR FORMATION RATES
PAHband is a reliable MIR proxyfor star formation rates.
In order to estimate thecircumnuclear star formation rates It is particularly well suited for the study of AGN due to
basedontheMIRphotometry,wedevelopedamethodbased its relative insensitivity to the radiation from the accretion
on the difference between the photometric fluxes already disk,whichisthoughttodestroythemolecules(Voit1992).
discussedandcarefulmeasurementsofthecontinuumslope. Thisisnotthecaseofatomicfinestructurelinessuchasthe
We stress that given the different redshifts of the galaxies 12.8µm[Neii],whichtendtooverestimateSFRinluminous
andthelargevariationsinsilicateprofilearound10µm,itis AGNs(Diamond-Stanic& Rieke2010).OtherPAHfeatures
impossible to determine the flux in PAH emission features onshorterwavelengths,suchasthe6.2,7.7and8.6µmfea-
based solely on the photometric fluxes. We refer the reader tures,havebeen shown tobesuppressed in Seyferts(ibid.).
to theappendix A for thetechnical details of this analysis. Based on templates of MIR spectra of starburst galax-
Ourresults,presentedintable2,showthat7outofthe iesfromRiekeet al.(2009),Diamond-Stanic& Rieke(2012)
15 galaxies in thesample havePAHemission. This number derived therelation
is different from theone presented in section 3.1 dueto the
different approach. Most importantly, simulating the PAH
emission bandprovidesinformation on theeffectsof having M˙∗ (M⊙ yr−1)=9.6×10−9LPAH(L⊙) (2)
some of the emission sampled by the reference filter. Also,
whileinsection3.1theimageswerecomparedonapixelby for starbursts characterised by M˙∗ < 10 M⊙ yr−1, where
pixel basis, in the present analysis only the integrated pho- LPAH is the luminosity from the PAH 11.3 µm band. This
tometry is considered, thus rendering PSF mismatch prob- equation has been evaluated for galaxies with 109.75 <
lems irrelevant. Therefore, not all galaxies identified in the LIR < 1010.75, with a dispersion of 0.28 dex. Our sam-
(cid:13)c 2016RAS,MNRAS000,1–9
Cicumnuclear star formation in AGNs 7
0.5 ESO005-G004 ESO138-G001 1.0 NGC1194 NGC2273 0.6
0.4 0.9 0.5
0.3 0.8 0.2 0.4
0.2 0.7 0.15 0.3
0.1 0.6 0.2
0.1
0.0 0.5 0.1
-0.1 0.4 0.05 0.0
ESO383-G035 IC4329A 1.3 NGC5128 NGC5506 1.6
1.2 1.4
0.35 1.1 1.5 1.2
y) 0.3 1.0 y) 1.0
y(J 0.25 00..89 y(J 01..50 00..68
nsit 0.01.52 00..67 nsit 0.0 00..24
de IC5063 Mrk1239 de 0.4 NGC5995 NGC6240 0.8
Flux 01..80 00..555 Flux 0.03.53 000...246
0.25
0.6 0.45 0.2 0.0
0.4 0.4 0.15 -0.2
1.6
NGC0253 NGC0931 NGC7469
1.4
8.0 1.2
0.25
6.0 1.0
0.2 0.8
4.0
0.6
2.0 0.15 0.4
0.09 10 11 12 9 10 11 12 0.1 0.29 10 11 12
Wavelength(µm) Wavelength(µm)
Figure 4. Spectra from Spitzer/IRS for the first 8 galaxies in Figure 5.Sameasfigure4forgalaxies9through15.
the sample. Blue lines are the observed spectra shifted to the
rest frame; red lines represent the continuum emission with the
silicateabsorption as considered bypahfit;vertical dotted lines Starburst luminosities, derived according to equation 4, for
markthewavelengthofthe10.5µm[Siv]lineand11.3µmPAH all the galaxies in thesample are presented in table 2.
band;greenlinesrepresentthebesttheoreticalmatchtothespec-
Itisimportant topointout thatof alltheseven galax-
trum. The dots are the photometric flux points shifted to the
ies in which we detected circumnuclear star formation, 4
central wavelength they aresamplingat the given redshift,with
have already been hinted at having such a characteris-
error bars representing the filter’s FWHM and uncertainties in
the flux measurements, in the horizontal and vertical directions tic by previous studies, namely ESO 138-G001, NGC 253,
respectively. NGC 2273 and NGC 5506 (Cid Fernandes et al. 2005;
Engelbracht et al. 1998; Mulchaey et al. 1996; Oliva et al.
1999).BasedontheassumptionthatMIRobservationspen-
ple has a median LIR = 1010.65 with three galaxies above etratedeeperintothedustynuclearenvironment,oneshould
LIR =1011,thereforeweconservativelyregarduncertainties expectsuchcases.Intheoppositedirection,NGC6240 and
in M˙∗ as 1 dex. NGC 7469 have previous detections of circumnuclear star
Proceeding in this line of thought, the energy-mass formation in the optical, but we find no evidence for it
equivalenceallowstheluminosityofthecircumnuclearstar- in our analysis. This could be either due to the detection
burst (LSB) to be expressed as function of the mass con- limitimposedhereor,inthecaseofNGC7469,becausethe
version rate from molecular gas to stars (M˙∗). Adding a starformation structureseenbypreviousauthorsisoutside
scaling factor of 0.14 Kawakatu & Wada (2008) write LSB, thepupilusedtoisolatethenuclearsource(seeSoifer et al.
at a particular instant, as 2003).
TheSFRestimatespresentedhereforthecircumnuclear
region ofsomeofthegalaxies areconsiderablysmaller than
LSB=0.14εM˙∗c2 (3) previous estimates for the entire galaxy found in the liter-
ature. In the case of NGC 6240 Howell et al. (2010) report
where c is the speed of light in the vacuum and ε is the
massconversionefficiencysetto0.007,whichisthefraction a SFR of 148.44 M⊙ yr−1 using Spitzer LIR and GALEX
FUV measurements, with the caveat that some AGN con-
of mass converted toenergy duringthefusion of Hydrogen.
taminationmaybepresent.Themostlikelyexplanationfor
These last twoequations,incgs units,result in thefol-
the smaller value of SFR presented here is the difference in
lowingrelation betweenPAHemission at11.3µmandstar-
the apertures, which is almost a factor of 10 smaller when
burst luminosities:
compared to that of Spitzer.
On the other hand NGC 253 and NGC 7469 have re-
LSB(erg s−1)=εc22.2×10−17LPAH (erg s−1). (4) ported SFRs for the nuclear region with spatial resolu-
(cid:13)c 2016RAS,MNRAS000,1–9
8 Daniel Ruschel-Dutra et al.
tions comparable to the ones in this paper, with values logBHAR(M⊙/yr)
of 2.8 ±0.3 M⊙ yr−1 and 2.6 −5.1 M⊙ yr−1 respectively −5 −4 −3 −2 −1 0 1 46
(tOartgtetestaarl.e210.015d;eDxaavnieds0e.t6adl.e2x0s0m7)a.llOeru,rtehsetrimefoarteesjufosrtitfyhiensge 2 8 4 SFR/100 SFR/10 45
theconservative uncertainty of 1 dex mentioned above. 1 6
9
5 DISCUSSION M/yr)⊙ 0 102 515 13 14 SFR 44(erg/s)
Astenlluamr benerviorfonthmeeonrtetiincalwshtiucdhieSsMhBavHe sahcocwrentiotnhaitstohbesienrtveerd- gSFR( −1 7 1 3 12 43L,NUCSB
o 11 g
also favour star formation in the circumnuclear region. For l 42lo
instance, Kawakatu & Wada (2008) using a semi-analytic −2
modelshowthatgivenacontinuoussupplyofgasfromouter
partsofthehostgalaxytotheinner100pc,AGNluminosity 41
−3
willbecorrelatedtoSBluminositywhiletheaccretionrates 40 41 42 43 44 45 46 47
are high. In another semi-analytic work Neistein & Netzer logLAGN(erg/s)
(2014) show that for SB and accretion events ignited by
Figure6.RelationbetweenAGNluminosityandthenuclearstar
galaxymergers,acorrelationbetweenLAGNandSFRisver- formationrate. Thenumbers correspondtotheidentification on
ified when LAGN >1042ergs−1. the first column of table 2. Dotted lines markaccretion rates in
In ordertoinvestigate thepossible physicalconnection termsof theSFR, inratiosof BHAR=SFR, BHAR=SFR/10
betweentheAGNandthecircumnuclearstarburst,wecom- andBHAR=SFR/100.Thesolidlineanddashedlinesarerepro-
pared the SFRs probed by the PAH emission to the accre- ductions of the semi-semi-analytic models in Neistein&Netzer
tionrateoftheAGNs.Thelatterquantitywasderivedfrom (2014,seetext).
theX-Ray2-10keVluminosity,withbolometriccorrections
obtained from
concludethattheSFRsareclose toBHARswhenconsider-
ing only the nuclear region (R < 10pc). The spread in the
log L12 = correlation increases as larger radii are considered, at the
(cid:20)L(2−10 keV)(cid:21) same time that BHARs correspond to smaller fractions of
1.54+0.24L12+0.012L212−0.0015L312 (5) SfoFrRths.eIdniffoeurrenatnaplryosjiesctweedhaarevaesntohteycormeppreensseanttebdetchaeusSeFtRhes
(Marconi et al. 2004), where L12 = log(LAGN) − 12 and majority of our sources is unresolved. As a result, some of
LAGN is the bolometric luminosity in units of L⊙. Numeri- thedispersioninfigure6canbedirectlylinkedtocomparing
calmethodswereusedtosolvethistranscendentalequation, different proportions of thehost galaxy.
resulting in correction factors roughly between 7 and 55. In figure 6 we also indicate the corresponding LSB for
Resulting bolometric luminosities for all the AGNs in our thecalculatedSFRs,meaningtheluminositydueexclusively
sample are also shown in table 2. We would like to empha- to young stars. The most striking feature is that there are
sise that thevalueof LAGN obtained from X-Rayradiation nogalaxieswhereLAGN >100×LSB.Inotherwords,allthe
is only representative of the instantaneous accretion rate AGN harbouring galaxies in our sample, even the most en-
of the BH. On the other hand, the emission from aromatic ergeticones,havestarburstsradiatingatleast1%oftheen-
moleculesusedtoassessSFRslags150Myrbehindthemain ergyfromthecentralengine.Atthesametime,thehighlu-
star formation event. minosity AGNshavecircumnuclear starbursts that at most
The points in figure 6 show the SFRs of circumnuclear matchtheenergyoutputofthecentralsource.Moreoverwe
regions versus the bolometric luminosities of the AGNs. In findthattwoofthesevenwellconstrainedgalaxiesliewithin
thesamegraphwecompareourresultswiththeoreticalpre- uncertainty limits of the 1-to-1 line, meaning that a signif-
dictions from Neistein & Netzer (2014) by overplotting the icant fraction of these sources have nearly as much energy
average SFRs and LAGN lines from figure 3 in the same comingfrom theAGNasfrom thecircumnuclearstarburst.
paper. The solid line represents the average SFR for each This reinforces the importance of isolating the AGN emis-
LAGN bin in Neistein & Netzer (2014) models, while the sion from star formation at theMIR.
dashed line marks the average LAGN for each SFR bin. We Concerning the low luminosity AGNs, there are is one
also note that the higher luminosity AGN in our sample galaxywhichhasmorethanonehundredtimesmoreenergy
(LAGN > 1042 (erg/s−1)) are mainly located in the region coming from young stars than from the AGN. This is in
these authors claim to be occupied by objects in the early agreementwithrecentstudiesshowingthehugeimportance
stages of the starburst. Observational evidence from longer of the circumnuclear star forming components at all wave-
wavelengths also show a similar trend for high luminosity lengthstounderstandLLAGN(e.g. Gonz´alez-Mart´ın et al.
AGNs.Forinstance,Rosario et al.(2012)using60µmdata 2014). Conversely, we find no examples of low luminos-
from the Herschell space telescope, found that local AGN ity AGNs with LSB << LAGN. Regarding the relation-
luminositiescorrelatewithSFRforLAGN >1044 (erg/s−1), ship between the luminosities from the different phe-
thusagreeing with our findings. nomena, our data agrees with the theoretical predictions
Through the use of hydrodynamical simulations of Kawakatu & Wada (2008) and Wutschiket al. (2013),
Hopkins& Quataert (2010) have predicted correlations be- whicharguethatlowluminosityAGNsshouldnotdisplaya
tween black hole accretion rates (BHAR) and SFR. They correlation betweencircumnuclearstarformation andAGN
(cid:13)c 2016RAS,MNRAS000,1–9
Cicumnuclear star formation in AGNs 9
activity. According to these authors, this lack of correla- REFERENCES
tion represents a stage where the circumnuclear disk has
Alonso-Herrero A. et al., 2014, Monthly Notices of the
becomegravitationally stable,thusceasingtheaccretionby
RoyalAstronomical Society, 443, 2766
theSMBH, but still has enough gas to form stars.
Alonso-HerreroA.etal.,2011, TheAstrophysicalJournal,
Diamond-Stanic & Rieke (2012) have found a positive
736, 82
correlation between BHAR and the SFR in radii averag-
ing to 300 pc, throughout their sample, using the [O iv] AsmusD.,HonigS.F.,GandhiP.,SmetteA.,DuschlW.J.,
2014,MonthlyNoticesoftheRoyalAstronomicalSociety,
as an indicator of the former. In that study, only two of
the four points with LAGN < 42 ergs−1 fall within the 439, 1648
Awaki H., Terashima Y., Higaki Y., Fukazawa Y., 2009,
correlation, leaving a further two points below it. This re-
Publications of the Astronomical Society of Japan, 61,
sult contrasts with our analysis in the sense that we would
S317
expect to see higher circumnuclear star formation in the
Bianchi S., Guainazzi M., Matt G., Fonseca Bonilla N.,
low luminosity regime. Using spectra rather than images,
PontiG., 2009, Astronomy and Astrophysics, 495, 421
Esquej et al.(2013)arrivedatcircumnuclearstarformation
Brightman M., Nandra K., 2011, Monthly Notices of the
detection rates similar to ours, almost half of their sample
RoyalAstronomical Society, 413, 1206
of 23 AGNs. We have four objects in common with their
work, and our estimates for 11.3µm PAH luminosity agree Cid Fernandes R., Heckman T., Schmitt H., Delgado R.
M. G., Storchi-Bergmann T., 2001, The Astrophysical
with theirs within theuncertainties.
Journal, 558, 81
CidFernandesR.,MateusA.,Sodr´eL.,StasiskaG.,Gomes
J. M., 2005, Monthly Notices of the Royal Astronomical
Society,358, 363
6 CONCLUSIONS Corral A., Della Ceca R., Caccianiga A., Severgnini P.,
Brunner H., Carrera F. J., Page M. J., Schwope A. D.,
We analysed MIR images of a sample of 15 AGNs in two
2011, Astronomy & Astrophysics,530, A42
adjacent filters (PAH2 and Si5 in the CanariCam, and
DaviesR.I.,MuellerSanchezF.,GenzelR.,TacconiL.J.,
PAH2 and PAH2 2 at VISIR) to study the occurrence of
Hicks E. K. S., Friedrich S., Sternberg A., 2007, The As-
circumnuclear star formation via the 11.3 µm PAH emis-
trophysical Journal, 671, 1388
sion band. Three of these 15 galaxies were observed with
Diamond-StanicA.M.,RiekeG.H.,2010,TheAstrophys-
GTC/CanariCam, and the remaining 12 with ESO/VISIR,
ical Journal, 724, 140
withimages takenfrom theatlaspublishedbyAsmus et al.
Diamond-StanicA.M.,RiekeG.H.,2012,TheAstrophys-
(2014). We have also presented new high resolution MIR
ical Journal, 746, 168
images for NGC 2146, which was eventually left out of the
D´ıaz-SantosT.,Alonso-HerreroA.,ColinaL.,PackhamC.,
remaining analysis due to the lack of a clearly detectable
LevensonN.A.,Pereira-SantaellaM.,RocheP.F.,Telesco
nucleus. Ourmain results are as follows.
C. M., 2010, The Astrophysical Journal, 711, 328
• Circumnuclearstarformation,atdistancesaslowas20 EngelbrachtC.W.,RiekeM.J.,RiekeG.H.,KellyD.M.,
pc from the nucleus, was detected in seven out of the 15 AchtermannJ.M.,1998,TheAstrophysicalJournal,505,
galaxies. Amongthese seven galaxies, four show unresolved 639
emission, NGC 253 has clearly identifiable star formation Esquej P. et al., 2013, arXiv.org, 1311, 703
nodes, and ESO 005-G004 and NGC 2273 have not been Ferrarese L., Merritt D., 2000, The AstrophysicalJournal,
detected in theimage subtraction. 539, L9
• The luminosity from the circumnuclear starburst cor- Filippenko A. V., Halpern J. P., 1984, The Astrophysical
relates with thebolometric luminosity of thecentral engine Journal, 285, 458
onlyforAGNswithluminosityhigherthan1042 erg s−1.In ForbesD.A.,Polehampton E.,StevensI.R.,Brodie J.P.,
the lower luminosity regime, we find that the radiative en- Ward M. J., 2000, Monthly Notices of the Royal Astro-
ergy output due to star formation tends to be higher than nomical Society, 312, 689
thecentral engine. GallimoreJ.F.etal.,2010,TheAstrophysicalJournalSup-
plement Series, 187, 172
Gebhardt K. et al., 2000, The Astrophysical Journal, 539,
L13
Gonz´alez-DelgadoR.M.,P´erezE.,1993,Astrophysicsand
ACKNOWLEDGEMENTS
SpaceScience, 205, 127
DRDthanksCNPqandCAPESforpartiallysupportingthis Gonz´alez-Mart´ın O., D´ıaz-Gonz´alez D., Acosta-Pulido
researchthroughfellowships.RRthanksCNPqandCAPES. J. A., Masegosa J., Papadakis I. E., Rodr´ıguez-Espinosa
PartiallybasedonobservationsmadewiththeGranTelesco- J.M.,M´arquezI.,Hern´andez-Garc´ıaL.,2014,Astronomy
pio Canarias (GTC), installed at the Spanish Observatorio & Astrophysics, 567, A92
delRoquedelosMuchachosoftheInstitutodeAstrof´ısicade Gonz´alez-Mart´ın O., Masegosa J., M´arquez I., Guerrero
Canarias, intheisland ofLaPalma.Thisresearchhasbeen M. A., Dultzin-Hacyan D., 2006, Astronomy and Astro-
partially supported by the Spanish Ministry of Economy physics,460, 45
and Competitiveness (MINECO) under the grant (project Gonz´alez-Mart´ın O. et al., 2013, Astronomy & Astro-
ref.AYA2012-39168-C03-01). OGMacknowledgestheJuan physics,553, A35
dela Cierva fellowship. Gonz´alez-Mart´ın O., Vaughan S., 2012, Astronomy & As-
(cid:13)c 2016RAS,MNRAS000,1–9
10 Daniel Ruschel-Dutra et al.
trophysics, 544, A80 AstrophysicalJournal, 312, 555
Greenhill L. J., Tilak A., Madejski G., 2008, The Astro- Rosario D. et al., 2012, Astronomy & Astrophysics, 545,
physical Journal, 686, L13 A45
GuainazziM.,FabianA.C.,IwasawaK.,MattG.,FioreF., Ruschel-Dutra D., Pastoriza M., Riffel R., Sales D. A.,
2005,MonthlyNoticesoftheRoyalAstronomicalSociety, WingeC.,2014,MonthlyNoticesoftheRoyalAstronom-
Volume356, Issue 1, pp.295-308., 356, 295 ical Society, 438, 3434
Gu¨ltekin K. et al., 2009, The Astrophysical Journal, 698,
RushB.,MalkanM.A.,SpinoglioL.,1993,TheAstrophys-
198
ical Journal SupplementSeries, 89, 1
Hao L. et al., 2005, The Astrophysical Journal, Volume
Sales D. a., Pastoriza M. G., Riffel R., 2010, The Astro-
625, Issue 2, pp.L75-L78., 625, L75
physicalJournal, 725, 605
Hopkins P. F., Quataert E., 2010, Monthly Notices of the
Sales D. a., Pastoriza M. G., Riffel R., Winge C.,
RoyalAstronomical Society, 407, 1529
Rodr´ıguez-ArdilaA.,Carciofia.C.,2011,TheAstrophys-
Howell J. H. et al., 2010, The Astrophysical Journal, Vol-
ical Journal, 738, 109
ume715, Issue 1, pp. 572-588 (2010)., 715, 572
Sales D. a., Ruschel-Dutra D., Pastoriza M. G., Riffel R.,
Kauffmann G. et al., 2003, Monthly Notices of the Royal
WingeC.,2014,MonthlyNoticesoftheRoyalAstronom-
Astronomical Society,346, 1055
ical Society, 441, 630
Kawakatu N., Wada K., 2008, The Astrophysical Journal,
681, 73 ShinozakiK.,MiyajiT.,IshisakiY.,UedaY.,OgasakaY.,
Kormendy J., Richstone D., 1995, Annual Review of As- 2006, The Astronomical Journal, 131, 2843
tronomy and Astrophysics, 33, 581 ShuX.W., Yaqoob T., WangJ. X., 2011, TheAstrophys-
Lira P., Johnson R. A., Lawrence A., Cid Fernandes R., ical Journal, 738, 147
2007,MonthlyNoticesoftheRoyalAstronomicalSociety, Siebenmorgen R., Kru¨gel E., Spoon H. W. W., 2004, As-
382, 1552 tronomy and Astrophysics, 414, 123
Marconi A., Risaliti G., Gilli R., HuntL. K., Maiolino R., Silk J., Rees M. J., 1998, Astronomy and Astrophysics
SalvatiM.,2004,MonthlyNoticesoftheRoyalAstronom-
SmithJ.D.T.etal.,2007,TheAstrophysicalJournal,656,
ical Society,351, 169
770
Marinucci A., Bianchi S., Nicastro F., Matt G., Goulding
Soifer B. T., Bock J. J., Marsh K., Neugebauer G.,
A.D., 2012, The Astrophysical Journal, 748, 130
MatthewsK.,Egami E.,ArmusL.,2003, TheAstronom-
Martini P., Regan M. W., Mulchaey J. S., Pogge R. W.,
ical Journal, 126, 143
2003, The Astrophysical Journal SupplementSeries, 146,
Stasiska G., Asari N. V., Fernandes R. C., Gomes J. M.,
353
Schlickmann M., Mateus A., Schoenell W., Sodr´e Jr L.,
Mason R. E. et al., 2012, The Astronomical Journal, 144,
2008,MonthlyNoticesoftheRoyalAstronomicalSociety:
11
Letters, 391
McConnell N.J., MaC.-P.,2013, TheAstrophysicalJour-
Sturm E. et al., 2005, The Astrophysical Journal, Volume
nal, 764, 184
629, Issue1, pp.L21-L23., 629, L21
Mulchaey J. S., Wilson A. S., Tsvetanov Z., 1996, The
Astrophysical Journal Supplement Series, 102, 309 Thompson G. D., Levenson N. A., Uddin S. A., Sirocky
Mu¨ller-S´anchez F., Gonz´alez-Mart´ın O., Ferna´ndez- M. M., 2009, The AstrophysicalJournal, Volume697, Is-
OntiverosJ. A., Acosta-PulidoJ. A., Prieto M.A., 2010, sue1, pp.182-193 (2009)., 697, 182
The Astrophysical Journal, 716, 1166 TielensA.,2008,AnnualReviewofAstronomyandAstro-
NandraK.,O’NeillP.M.,GeorgeI.M.,ReevesJ.N.,2007, physics,46, 289
Monthly Notices of the Royal Astronomical Society, 382, UedaY.et al., 2011, Publications of theAstronomical So-
194 ciety of Japan, 63, S937
NeisteinE.,NetzerH.,2014,MonthlyNoticesoftheRoyal UedaY.,IshisakiY.,TakahashiT.,MakishimaK.,Ohashi
Astronomical Society,437, 3373 T., 2005, The Astrophysical Journal Supplement Series,
Nenkova M., Sirocky M. M., Ivezi´c v., Elitzur M., 2008, 161, 185
The Astrophysical Journal, 685, 147 V´eron-CettyM.-P.,V´eronP.,2010,AstronomyandAstro-
OlivaE.,OrigliaL.,MaiolinoR.,MoorwoodA.F.M.,1999, physics,518, A10
Astronomy and Astrophysics, 350, 9
VoitG.M.,1992,MonthlyNoticesoftheRoyalAstronom-
Ott J., Weiss A., Henkel C., Walter F., 2005, The Astro-
ical Society (ISSN0035-8711), 258, 841
physical Journal, Volume 629, Issue 2, pp. 767-780., 629,
VollmerB.,DaviesR.I.,2013,Astronomy&Astrophysics,
767
556, A31
Piconcelli E., Bianchi S., Vignali C., Jim´enez-Bail´on E.,
WinterL.M.,MushotzkyR.F.,ReynoldsC.S.,TuellerJ.,
Fiore F., 2011, Astronomy & Astrophysics, 534, A126
2009, The Astrophysical Journal, 690, 1322
Ramos Almeida C. et al., 2011, Monthly Notices of the
Wu Y., Charmandaris V., Huang J., Spinoglio L., Tom-
RoyalAstronomical Society: Letters, 417, L46
masin S., 2009, The Astrophysical Journal, 701, 658
Rieke G. H., Alonso-Herrero A., Weiner B. J., P´erez-
Gonz´alez P. G., Blaylock M., Donley J. L., Marcillac D., Wutschik S., Schleicher D. R. G., Palmer T. S., 2013, As-
2009, The Astrophysical Journal, 692, 556 tronomy & Astrophysics, 560, A34
RiffelR., Pastoriza M.G., Rodr´ıguez-Ardila A.,Maraston
C., 2007, The Astrophysical Journal, 659, L103
RodriguezEspinosaJ.M.,RudyR.J.,JonesB.,1987,The
(cid:13)c 2016RAS,MNRAS000,1–9