BLACK HOLE MASSES AND EDDINGTON RATIOS OF AGNs AT z

20 Pages·2007·0.94 MB·English

TheAstrophysicalJournal,667:97Y116,2007September20 A
#2007.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A.
BLACK HOLE MASSES AND EDDINGTON RATIOS OFAGNs AT z <1: EVIDENCE OFRETRIGGERING
FORAREPRESENTATIVESAMPLEOFX-RAY-SELECTEDAGNs
L. Ballo,1,2 S. Cristiani,3 G. Fasano,4 F. Fontanot,5 P. Monaco,5,3 M. Nonino,3 E. Pignatelli,4
P. Tozzi,3 E. Vanzella,3 A. Fontana,6 E. Giallongo,6 A. Grazian,6 and L. Danese1
Received2005December29;accepted2007May1
ABSTRACT
WeestimatedblackholemassesandEddingtonratiosforasampleofX-ray-selectedactivegalacticnuclei(AGNs)
inthefieldscoveredbytheGreatObservatoryOriginsDeepSurvey(GOODS).Thespannedrangesinredshift(0:4<
z<1)andhardX-rayluminosity(1042 PL P4;1043ergss(cid:1)1)allowustostudyarepresentativesubsampleofthe
X
maincontributorstothe2Y10keVX-raybackground.Nuclearandbulgemagnitudesinfourbandshavebeenmea-
suredviaatwo-dimensionaldecompositionappliedtoHSTACSimages.Usingtheblackholeversusbulgeluminos-
ityrelationandthe intrinsicnuclearemission,wederivedtheblackholemassandtheAGNbolometricluminosity.
Wefindinoursamplethat(1)theX-rayYtoYopticalindicesarelargerthaninopticallyselectedQSOs,asexpecteddue
totheX-rayselection);(2)theX-raybolometriccorrectionsaregenerallysmall,suggestingadecreasewiththenu-
clearluminosity;(3)theEddingtonratiosareaboutafactor10belowthevaluesfoundathigherredshiftandlumi-
nosity;(4)thecentralblackholeshaveratherlargemasses;and(5)atleastforzP0:8,ascarcenessofblackholeswith
massM (cid:2)106M andaccretionrateneartheEddingtonlimit:thisresultcouldbeascribedtoadeclineintheirnum-
BH (cid:3)
berdensity,oritcouldsuggestasubstantialaccretionathigherredshift(zk1)alsoforthesesmallerblackholes.
Subject headingsg: black hole physics — galaxies: active — galaxies: nuclei — galaxies: photometry —
X-rays: diffuse background — X-rays: galaxies
Online material: color figures
1. INTRODUCTION michistoryofSMBHaccretion.Asanultimategoal,oneshould
matchthemassfunctionoftheBHaccretedmasswiththelocal
Recent Chandra and XMM-Newton deep surveys (Brandt
massfunctionofthequiescentBHs(see,e.g.,Saluccietal.1999;
etal.2001;Rosatietal.2002;Hasingeretal.2001)haveresolved
(cid:4)90% ofthe 2Y10keV X-ray background(hereafter XRB;see Yu&Tremaine2002;Marconietal.2004;Shankaretal.2004).
ThedetailedhistoryofSMBHaccretionisalsoarelevantclue
Baueretal.2004).ThemaincontributiontotheXRBinthisen-
tounderstandtheobservedrelationshipsbetweenthemassoflo-
ergyrangeisduetoamixtureofobscuredandunobscuredactive
calSMBHsandthemassandluminosity(Kormendy&Richstone
galactic nuclei (AGNs), with a redshift distribution peaking at
1995;Magorrianetal.1998;McLure&Dunlop2002;Marconi&
(cid:4)0.7(Szokolyetal.2004),andamajorcontributionintheinter-
Hunt2003)orthevelocitydispersion(Ferrarese&Merritt2000;
val0:4<z<1fromobjectswithX-rayluminositiesbetween
3;1041 and1043ergss(cid:1)1(Uedaetal.2003). Gebhardtetal. 2000; Merritt & Ferrarese 2001; Tremaine etal.
2002)ofthespheroidalcomponentoftheirhostgalaxies.Even-
Themassaccretedontothecentralsupermassiveblackholes
tually,thiswillcastlightonphysicalprocessesinvolvingboththe
(SMBHs)ofthesez<1AGNsisestimatedtobe(cid:4)30%ofthe
SMBH and the host galaxy (Silk & Rees 1998; Granato et al.
totalmassdensityaccretedatanyredshift(Marconietal.2004;
2001,2004;Hopkinsetal.2005).
Shankaretal.2004).Animportantquestioniswhetherthisac-
In this paper we estimate the BH mass, the bolometric lu-
cretedmassisonaveragefallingontoSMBHsalreadyhavingvery
minosityandtheEddingtonratioforarepresentativesampleof
largemass((cid:1)M /M T1),oriftheaccretionisoccurringon
acc BH low-luminosity X-ray-selected AGNs in the redshift interval
smallerSMBHs.ThefirstregimecorrespondstoEddingtonratios
0:4(cid:2)z(cid:2)1.
k¼L /L T1andcanbeassociatedwithreactivationofpre-
bol Edd Thedatademandsaresubstantialforastudysuchasours.High
existingblackholes(BHs),whilethelattercorrespondstokP1
spatialresolutionandhighsignal-to-noiseratiodataintheX-ray
andisassociatedwiththemainepisodeofgrowthoflowermass
produced by the Chandra observations in the Chandra Deep
BHs.Thisissueisrelevantinordertoreconstructthedetailedcos-
FieldsSouthandNorth(Giacconietal.2002;Rosatietal.2002;
Alexander et al. 2003) are offundamental importance to select
1 SISSA/ISAS,InternationalSchoolforAdvancedStudies,34014Trieste, low-luminosityAGNs.Wealsoneedopticalimageswithexcel-
Italy;[email protected],[email protected]. lentspatialresolutionandveryhighqualityphotometry,inorder
2 EuropeanSpaceAstronomyCenterofESA,E-28080Madrid,Spain;lballo@ todisentangle the galacticand nuclear components, and toesti-
sciops.esa.int. mate the AGN bolometric luminosity and the BH mass. In this
3 INAFYOsservatorioAstronomicodiTrieste,34131Trieste,Italy;cristiani@
respecttheGreatObservatoriesOriginsDeepSurvey(GOODS;
oats.inaf.it,[email protected],[email protected],[email protected],vanzella@
oats.inaf.it. seeGiavaliscoetal.2004)isreallyunique;infact,inadditionto
4 INAFYOsservatorioAstronomicodiPadova,35122Padova,Italy;fasano@ deepX-rayandopticalimagesfromtheChandraX-RayObser-
pd.astro.it,[email protected]. vatory andtheHubbleSpaceTelescope(HST),italsoexploitsex-
5 DAUT,34131Trieste,Italy;[email protected],[email protected].
tensivefollow-upworkwithground-basedtelescopes,extending
6 INAFYOsservatorioAstronomicodiRoma,00040MontePorzioCatone,
thesamplingoftheelectromagneticspectrumofthesourcesupto
Italy;[email protected],[email protected],[email protected]
.it. theradiowavelength.
97
98 BALLO ETAL. Vol. 667
Thepaperisorganizedasfollows.Inx2(butseealsoAppen-
dixA)wedescribethesampleselectionandlistthedifferentdata
sets available. In x 3 we introduce the morphological analysis
carriedout(detailsarereportedinAppendixB)anddiscussthe
resultsofthedecomposition.Section4isdevotedtorecoverthe
nuclear properties (i.e., BH masses and nuclear bolometric lu-
minosities).Inx5ourfindingsarediscussedandcomparedwith
resultsfromtheliterature.Finally,inx6wesummarizeourwork.
If not otherwise stated, throughout this paper magnitudes are
givenintheABsystem,andhardX-rayluminositiesareinthe
2Y8keVenergyrange(whennecessary,convertedfromL2Y10keV
assuming a power-law X-ray spectrum with photon index (cid:2)¼
1:8: L2Y8keV/L2Y10keV ’0:84). We assume a cosmology with
(cid:3) ¼0:3,(cid:3) ¼0:7,andH ¼70kms(cid:1)1Mpc(cid:1)1(Spergeletal.
M (cid:4) 0
2003,2007).
2. SAMPLE SELECTION
The starting point for the present work is the deep, high-
resolution optical imaging performed in the F435W, F606W,
F775W,andF850LPfilterswiththeAdvancedCameraforSur-
veys(ACS)onboardHSTintheframeworkoftheGOODSpro-
gram.Inthefollowing,werefertothesefourpassbandsasB,V,
i,andz,respectively.GOODScoversatotalareaof 320arcmin2
intwofieldscenteredontheChandraDeepFieldYSouth(CDF-S)
andtheChandraDeepFieldYNorth(CDF-N).Thesetworegions
havebeentargetsofdeepX-raypointings(1Ms[seeGiacconi
etal.2002;Rosatietal.2002;Alexanderetal.2003] and2Ms
[seeAlexanderetal.2003],respectively)carriedoutbyChandra.
Overall,80%ofobjectshaveredshiftinformation.Ifwerestrict
ourselvestotheCDFareascoveredbyGOODS,(cid:4)98%ofthe
X-rayobjectshaveopticalcounterparts. In theGOODSnorth
field, 63% and 17% of the X-ray sources have spectroscopic
andphotometric redshift,respectively;inthesouthareathese
percentagesincreaseto68%and32%,respectively.
We collect all the sources in the Chandra X-ray catalogs
lyingintheGOODSfieldswithredshift(spectroscopicorphoto-
metric)between0.4and1,andwithX-rayluminosityL2Y8keV >
1042ergss(cid:1)1inordertoselectbonafideAGNs(Zezasetal.1998;
Moran et al. 1999). They amount to 66 sources, 88% of them
havingspectroscopicredshifts.Theredshiftintervalischosento
bracketasignificantfractionofthelow-luminositysourcescon-
tributingtotheXRB.Theupperboundz¼1isimposedbythe
needofasufficientsignal-to-noiseratiotomakeamorphological
analysisformostofthesources.Thisupperlimitontheredshift
alsoensuresthattheobservedz-bandisalwayssamplingtheop-
ticalrestframe.Inordertocarryoutthemorphologicalanalysis
described in the next section, the simultaneous availability of
Fig.1.—Top:HardX-rayfluxesvs.i-bandmagnitudesfortheX-raysources
high-quality,noncrowdedB,V,i,and zACSsubimages(cutouts)
intheGOODSfieldswith(dots)andwithout(opencircles)redshiftinformation.
isessential.Thisselectionreducesthesampleto25sourcesinthe Bottom:i-bandmagnitudesvs.redshiftforX-raysourcesintheGOODSfields
CDF-Sand28intheCDF-N(sampleA). withredshiftinformation,withsuperimposedthei-bandmagnitudesexpected
FulldetailsoftheselectionprocessaregiveninAppendixA. forbulgeswithblackholemassesofMBH¼105,106and107M(cid:3)(fromtopto
bottom:solidlineandopentriangles,dottedlineandstars,anddashedlineand
HereletusnotethattheX-raysourcesintheGOODSfieldswith
filledsquares,respectively).
a redshift determination cover the same region in the F -F
X opt
planeasthewholedatabaseofthe‘‘GOODSX-raysources’’(see
Fig.1,toppanel),althoughmostoftheobjectswithoutredshift forthreeblackholemasses(fromtoptobottom,M ¼105,106,
BH
determinationhavefaintopticalcounterpart.Accordingtoabi- 107 M ) withthedistributionofthe optical magnitude ofX-ray
(cid:3)
dimensional Kolmogorov-Smirnov (K-S) test, there is no evi- sourcesintheGOODSfieldswitharedshiftdetermination.The
dencethatthetwosamplesaredrawnfromdifferentdistributions selectedrangeinredshiftandtheavailablemagnitudesdonotim-
(the K-S probability is (cid:4)60%). This makes us confident that plythatweareforcedtostudyonlyblackholewithlargemasses.
selectingonlysourceswithredshiftdeterminationdoesnotinduce Figure2showshowthesampleAisdistributedinredshift(top
a bias toward optically bright objects. Moreover, assuming the leftpanel),hardX-rayluminosity(toprightpanel),andoptical
blackholemassYbulgeluminosityrelations,wecanestimatehow magnitude(bottompanel).Thespikesvisibleintheredshiftdis-
brightabulgewithagivenblackholemasswouldbeatagiven tribution trace the large-scale structure identified in the whole
redshift:inthebottompanelof Figure1,wecomparethetracks CDF-Satz¼0:67andz¼0:73,bothintheoptical(Vanzella
No. 1, 2007 M AND EDDINGTON RATIOS OFAGNs AT 0.4 < z < 1 99
BH
Fig.2.—Distributionsinredshift(topleftpanel),hardX-rayluminosity(toprightpanel),and i-bandmagnitude(bottompanel)forthesampleA(GOODSX-raysources
withspectroscopicorphotometricredshiftsbetween0.4and1,observedhardX-rayluminosityL2Y8keV>1042ergss(cid:1)1,andgoodcutoutsinallbands;seex2);hatched
areasshowthesamedistributionsfortheanalyzedsources(sampleB).RedshiftsarefromSzokolyetal.(2004),Grazianetal.(2006),andZhengetal.(2004)fortheCDF-S,
andfromBargeretal.(2003)fortheCDF-N;luminositiesarefromAlexanderetal.(2003);i-bandmagnitudesarefromtheGOODSACScatalog(seefootnote12).
etal. 2005)and in the X-rayranges (Gilli et al. 2003), and at redshiftdistributions(theK-Sprobabilitiesare99%and75%,
z(cid:4)0:85intheCDF-N(seeBargeretal.2003;Gillietal.2005). respectively).
We have removed from the sample A objects with a close ThecontributionstothehardXRB7ofthesampleAis16%.
companion(withinaprojectedradiusof200,withoutdistinction InFigure3wecomparethetotalcontributiontothehardXRB
between physical interaction or projection effect; see also Ap- computedfromtheCDF-SplusASCA sample(DellaCecaetal.
pendixB);inthiswaytheanalyzedsample(sampleB)reducesto 2001; long-dashed line,withthethegrayarearepresentingthe
34 objects (19 in the CDF-S and 15 in the CDF-N), listed in estimateduncertainties;seeTozzi2001)withtheintegratedcon-
Table1.AsisapparentinFigure2,theredshiftandluminosity tributionofthesampleA(solidline)andoftheselected34sources
distributions of the sample B (hatched areas) match the distri-
butionsofthesampleA,apartfromaslightdearthofobjectswith
7 Average total flux density in the 2-8 keV band: (1:79(cid:5)0:11) ;
zk0:8.AccordingtoaK-Stest,wecannotprovethatthetwo 10(cid:1)11ergscm(cid:1)2s(cid:1)1deg(cid:1)2,fromDeLuca&Molendi(2004)convertedfrom
samples are drawn from different hard X-ray luminosity or the2Y10keVbandassuming(cid:2)¼1:4.
100 BALLO ETAL.
TABLE1
BasicInformationforX-Ray-selectedAGNs
(ObservedL2Y8keV>1042 ergss(cid:1)1)intheGOODSFields
with0:4<z<1AnalyzedinThisWork(SampleB)
R.A. Decl. logL2Y8keV iAB
(J2000.0) (J2000.0) ID Redshift (ergss(cid:1)1) (mag)
(1) (2) (3) (4) (5) (6)
CDF-N
123618.58......... +621115.0 114 0.679 43.20 20.46
123625.01......... +622115.7 141 0.747 42.29 21.87
123627.75......... +621158.4 150 0.762 42.34 23.10
123632.59......... +620759.8 170 0.680 42.16 21.83
123635.86......... +620707.7 194 0.555 42.37 21.99
123642.24......... +620612.8 222 0.857 42.60 21.38
123646.33......... +621404.7 243 0.961 43.62 21.57
123654.58......... +621110.6 285 0.955 42.43 22.47 Fig.3.—Contributiontothe2Y8keVX-rayfluxdensityasafunctionofthe
123659.09......... +622523.7 303 0.678 42.97 20.76 resolvedsources:comparisonbetween(1)thetotalresolvedcontribution(long-
123702.43......... +621926.1 323 0.514 43.27 19.70 dashedline,withgrayarearepresentingtheestimateduncertainties)computed
123710.07......... +620547.9 368 0.935 42.09 23.69 fromthe1MsCDF-SsampleplusthebrightsamplefromASCA (DellaCecaetal.
123722.44......... +620536.1 404 0.978 42.61 21.87 2001)atfluxeslargerthan10(cid:1)13ergscm(cid:1)2s(cid:1)1;seeTozzi(2001);(2)thecontribu-
tionofourinitialselection(sampleA:GOODSX-raysourceswithspectroscopic
123724.00......... +621304.3 412 0.474 42.33 24.25
orphotometricredshiftsbetween0.4and1,observedhardX-rayluminosity
123731.73......... +621703.7 439 0.839 42.61 20.89
123739.46......... +622239.2 451 0.838 42.27 21.39 L2Y8keV>1042ergss(cid:1)1andwithgoodcutoutsinallbands;continuousline);
(3)thecontributionoftheanalyzedsources,asinTable1(sampleB;dashedline).
ThetopdottedlinesrefertopreviousmeasuresoftheunresolvedhardX-ray
CDF-S
background; frombottomtotop:Marshalletal.(1980),Uedaetal.(1999),
Ishisakietal.(2001),andVecchietal.(1999).
033233.02......... (cid:1)274547.4 34 0.839 42.93 22.19
033226.76......... (cid:1)274145.6 40 0.667 42.85 21.61
033227.00......... (cid:1)274105.1 42 0.734 44.17 19.12
constructmultiwavelengthspectralenergydistributions(SEDs)
033227.61......... (cid:1)274145.0 44 0.737 42.65 21.89
fortheanalyzedobjects,seex3:
033224.84......... (cid:1)275600.0 47 0.733 42.64 21.44
033224.84......... (cid:1)275600.0 48 0.534 42.48 20.61 CDF-S.—GOODS has imaged these fields at 3.6, 4.5, 5.8,
033220.07......... (cid:1)274447.0 51 0.670 42.35 23.76 and 8.0 (cid:1)m with the Infrared Array Camera (IRAC) onboard
033217.18......... (cid:1)275220.9 52 0.569 42.88 20.84 Spitzer.Foreachfield,observationshavebeendividedintotwo
033220.07......... (cid:1)274447.0 151 0.604 42.36 22.11 epochs,withameanexposuretimeperchannelperskypointing
033208.24......... (cid:1)274153.6 156 0.545 42.07 21.80 ofapproximately23hrperepoch(M.Dickinsonetal.2007in
033246.98......... (cid:1)274346.2 170 0.664 42.14 20.00 preparation).InthisworkwewillmakeuseoftheSpitzerdatafor
033222.51......... (cid:1)274804.8 189 0.734 42.04 22.64
the CDF-S as analyzed by Grazian et al. (2006). The GOODS
033235.23......... (cid:1)275317.8 192 0.733 42.48 21.76
field of the CDF-S has also been the target of a deep imaging
033239.73......... (cid:1)274611.2 201 0.679 42.39 25.38
campaigninthenear-infraredwiththeESOtelescopes.Alarge
033218.99......... (cid:1)274755.4 252 0.481 42.13 24.71
field (200;200) has been covered with the SOFI instrument at
033213.92......... (cid:1)275000.7 257 0.549 42.08 22.44
033213.83......... (cid:1)274525.6 266 0.735 42.01 21.23 theNewTechnologyTelescope(NTT)intheJandKsbandsas
033234.73......... (cid:1)275533.8 511 0.668 42.08 21.44 partoftheDeepPublicSurveycarriedoutbytheESOImaging
033223.88......... (cid:1)275842.4 613 0.910 42.29 22.54 Survey(EIS)program;thedataaredescribedinVandameetal.
(2001).An H-bandsurveyoftheCDF-S,encompassingthespa-
Notes.—Cols.(1)and(2):unitsofrightascensionarehours,minutes,and tialcoverageoftheEISobservations,hasbeencarriedoutwith
seconds, and units of declination are degrees, arcminutes, and arcseconds;
thesameinstrument;theresultsarepresentedinMoyetal.(2003).
col.(3):sourcenumber;col.(4):redshiftfortheopticalcounterpart,fromBarger
etal.(2003),Szokolyetal.(2004),Grazianetal.(2006),andZhengetal.(2004); TheGOODSfieldisbeingcoveredbydeeperobservationsinthe
col.(5):observedX-rayluminosityinthe2(cid:1)8keVband;col.(6):ABmagnitude samenear-IRbandswiththeISAACinstrumentattheVLT.These
intheibandfromtheGOODSACScatalog(seefootnote12). datahavebeenpartiallyreleasedbyESOandwillbeusedinthis
work.8WealsomakeuseofU-banddatatakenwiththeESOWide
FieldImager(WFI)atLaSilla(Chile),whicharepartoftheEIS
(dashedline):thiscomparisonshowsthatwiththeanalyzedsources
publicsurvey(Arnoutsetal.2001),aswellasrecent Uimages
wearesamplinginanuniformwaythesamerangeoffluxofthe
withVLT-VIMOSimager.TheWFIimageshavebeenobtainedin
sampleA.Insummary,sampleBisconsideredrepresentativeof
thewholepopulationofX-raysourceswithspectroscopicorpho- twofilters,theso-calledU35andU38filters,withanexposuretime
tometric redshifts between 0.4 and 1 and luminosity L2Y8keV > of(cid:4)54and(cid:4)75ks,respectively.TheU-bandimageofVIMOS
1042ergss(cid:1)1,andonlyscaled(i.e.,sparselysampled)byafactor7. isbasedonaredderfilterandhasanexposuretimeof(cid:4)10ks.
BoththesampleAandtheanalyzedobjectscovertheluminosity ThecoveragewithVIMOSoftheGOODSfieldcenteredonthe
range1042 (cid:2)L2Y8keV (cid:2)3;1043ergss(cid:1)1,whileonlyfewsources CDF-Sispartial,sincetheobservingprogramhasnotbeencom-
pletedyet.
exhibitlargerluminosity.Takingintoaccounttheredshiftandlu-
minositydistributions,wecanconcludethatthesampleBisrep- CDF-N.—In the CDF-N IR information has been collected
matchingoursourceswiththeHK0catalogofCapaketal.(2004),
resentativeoftheAGNscontributingtotheXRBatz(cid:2)1(see,
e.g.,Fig.16inUedaetal.2003).
Data from U-band to IR, available thanks to the remarkable 8 ThedetailsoftheongoingGOODSprogramatESOaregivenathttp://
multiwavelengthcoverageofthetwoGOODSfields,areusedto www.eso.org/science/goods/products.html.
TABLE2
Two-dimensionalImageFittingMagnitudes
Nucleus Disk Bulge
ID z i V B z i V B z i V B
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)
CDF-N
114............. 21.66(cid:5)0.20 21.81(cid:5)0.22 21.72(cid:5)0.21 22.02(cid:5)0.28 ... ... ... ... 20.52(cid:5)0.21 20.81(cid:5)0.22 22.32(cid:5)0.24 25.52(cid:5)0.25
141............. 25.57(cid:5)0.38 25.81(cid:5)0.41 26.00(cid:5)0.41 26.16(cid:5)0.43 22.84(cid:5)0.30 23.22(cid:5)0.31 24.42(cid:5)0.33 25.62(cid:5)0.34 21.71(cid:5)0.26 22.43(cid:5)0.27 23.81(cid:5)0.28 26.91(cid:5)0.36
150............. 26.66(cid:5)0.40 27.07(cid:5)0.42 27.83(cid:5)0.41 28.85(cid:5)0.50 23.90(cid:5)0.30 24.25(cid:5)0.31 25.32(cid:5)0.34 26.19(cid:5)0.36 23.15(cid:5)0.27 23.61(cid:5)0.28 25.63(cid:5)0.30 30.25(cid:5)0.35
170............. 25.82(cid:5)0.40 26.12(cid:5)0.41 26.87(cid:5)0.41 27.56(cid:5)0.43 22.90(cid:5)0.36 23.11(cid:5)0.37 23.93(cid:5)0.38 24.70(cid:5)0.41 21.72(cid:5)0.20 22.13(cid:5)0.22 23.67(cid:5)0.24 27.08(cid:5)0.24
194............. 27.67(cid:5)0.42 27.86(cid:5)0.45 28.31(cid:5)0.44 28.10(cid:5)0.48 22.25(cid:5)0.26 22.26(cid:5)0.26 23.25(cid:5)0.27 24.26(cid:5)0.28 22.63(cid:5)0.22 23.49(cid:5)0.23 24.76(cid:5)0.25 27.35(cid:5)0.29
222............. 24.59(cid:5)0.36 24.85(cid:5)0.36 25.56(cid:5)0.38 26.10(cid:5)0.41 21.78(cid:5)0.22 22.01(cid:5)0.23 23.03(cid:5)0.26 23.96(cid:5)0.26 21.58(cid:5)0.28 22.24(cid:5)0.29 24.27(cid:5)0.28 26.74(cid:5)0.31
243............. 24.43(cid:5)0.35 24.21(cid:5)0.37 24.53(cid:5)0.37 25.93(cid:5)0.39 21.55(cid:5)0.21 22.18(cid:5)0.24 23.17(cid:5)0.23 24.15(cid:5)0.25 21.66(cid:5)0.32 22.68(cid:5)0.35 24.50(cid:5)0.34 26.85(cid:5)0.37
285............. 25.83(cid:5)0.36 26.01(cid:5)0.35 26.54(cid:5)0.37 26.94(cid:5)0.38 23.00(cid:5)0.33 23.82(cid:5)0.34 25.41(cid:5)0.34 26.58(cid:5)0.35 22.01(cid:5)0.31 22.87(cid:5)0.32 24.94(cid:5)0.36 29.01(cid:5)0.37
303............. 23.93(cid:5)0.31 24.23(cid:5)0.33 23.98(cid:5)0.34 24.04(cid:5)0.36 21.47(cid:5)0.24 22.01(cid:5)0.25 22.93(cid:5)0.25 23.75(cid:5)0.26 20.98(cid:5)0.26 21.26(cid:5)0.26 22.85(cid:5)0.28 26.05(cid:5)0.30
323............. 21.58(cid:5)0.22 21.74(cid:5)0.23 21.32(cid:5)0.22 21.34(cid:5)0.25 21.86(cid:5)0.23 21.93(cid:5)0.24 22.59(cid:5)0.26 23.02(cid:5)0.28 19.80(cid:5)0.20 20.08(cid:5)0.21 21.29(cid:5)0.22 24.02(cid:5)0.24
368............. 24.61(cid:5)0.38 25.17(cid:5)0.38 26.89(cid:5)0.40 28.21(cid:5)0.43 ... ... ... ... 23.25(cid:5)0.21 23.98(cid:5)0.22 25.41(cid:5)0.24 30.75(cid:5)0.28
404............. 24.52(cid:5)0.38 24.55(cid:5)0.37 25.09(cid:5)0.39 26.01(cid:5)0.40 22.11(cid:5)0.28 22.73(cid:5)0.31 23.79(cid:5)0.33 24.09(cid:5)0.34 21.83(cid:5)0.28 22.67(cid:5)0.30 24.05(cid:5)0.35 26.70(cid:5)0.38
412............. 26.52(cid:5)0.40 26.08(cid:5)0.41 26.25(cid:5)0.41 26.14(cid:5)0.43 24.33(cid:5)0.20 24.81(cid:5)0.22 25.40(cid:5)0.24 25.50(cid:5)0.24 25.21(cid:5)0.36 25.80(cid:5)0.37 26.81(cid:5)0.38 29.30(cid:5)0.41
439............. 24.27(cid:5)0.33 23.70(cid:5)0.33 23.93(cid:5)0.32 24.65(cid:5)0.35 21.46(cid:5)0.24 21.93(cid:5)0.24 22.89(cid:5)0.25 23.30(cid:5)0.27 21.01(cid:5)0.26 21.66(cid:5)0.27 23.17(cid:5)0.32 26.83(cid:5)0.33
451............. 24.57(cid:5)0.38 24.88(cid:5)0.37 25.12(cid:5)0.39 25.43(cid:5)0.40 22.73(cid:5)0.31 22.97(cid:5)0.31 24.63(cid:5)0.33 25.83(cid:5)0.36 20.87(cid:5)0.28 21.74(cid:5)0.30 23.63(cid:5)0.31 26.31(cid:5)0.35
CDF-S
34............... 23.85(cid:5)0.35 24.89(cid:5)0.35 25.18(cid:5)0.36 25.20(cid:5)0.36 22.40(cid:5)0.33 22.68(cid:5)0.33 23.63(cid:5)0.34 24.17(cid:5)0.36 22.74(cid:5)0.32 23.51(cid:5)0.33 24.91(cid:5)0.36 27.87(cid:5)0.38
40............... 25.04(cid:5)0.40 25.34(cid:5)0.41 25.63(cid:5)0.43 25.84(cid:5)0.45 22.86(cid:5)0.34 23.19(cid:5)0.35 23.68(cid:5)0.35 24.58(cid:5)0.36 21.76(cid:5)0.21 21.98(cid:5)0.24 23.61(cid:5)0.28 25.90(cid:5)0.30
42............... 18.96(cid:5)0.22 19.10(cid:5)0.24 19.25(cid:5)0.26 19.36(cid:5)0.26 ... ... ... ... 23.18(cid:5)0.32 24.30(cid:5)0.32 26.02(cid:5)0.35 28.68(cid:5)0.35
44............... 25.29(cid:5)0.38 25.16(cid:5)0.40 25.51(cid:5)0.43 26.04(cid:5)0.46 22.11(cid:5)0.28 22.74(cid:5)0.29 23.66(cid:5)0.31 24.78(cid:5)0.31 22.31(cid:5)0.31 22.64(cid:5)0.32 24.47(cid:5)0.33 27.59(cid:5)0.35
47............... 23.45(cid:5)0.33 23.62(cid:5)0.34 23.88(cid:5)0.36 24.57(cid:5)0.36 21.93(cid:5)0.26 22.32(cid:5)0.27 23.48(cid:5)0.27 24.04(cid:5)0.28 21.86(cid:5)0.29 22.34(cid:5)0.29 23.76(cid:5)0.30 26.52(cid:5)0.32
48............... 23.47(cid:5)0.34 23.60(cid:5)0.35 24.18(cid:5)0.35 24.36(cid:5)0.37 21.81(cid:5)0.25 22.44(cid:5)0.25 23.32(cid:5)0.27 24.69(cid:5)0.28 20.52(cid:5)0.20 20.92(cid:5)0.21 22.23(cid:5)0.21 25.10(cid:5)0.23
51............... 25.82(cid:5)0.39 25.67(cid:5)0.39 26.19(cid:5)0.41 27.42(cid:5)0.43 24.56(cid:5)0.35 24.86(cid:5)0.36 26.05(cid:5)0.37 27.67(cid:5)0.39 24.02(cid:5)0.28 24.23(cid:5)0.30 26.10(cid:5)0.32 27.91(cid:5)0.35
52............... 23.02(cid:5)0.35 22.88(cid:5)0.34 23.59(cid:5)0.35 23.57(cid:5)0.38 20.90(cid:5)0.23 21.33(cid:5)0.24 22.08(cid:5)0.26 24.38(cid:5)0.28 22.21(cid:5)0.30 23.05(cid:5)0.32 24.31(cid:5)0.33 26.56(cid:5)0.33
151............. 25.41(cid:5)0.38 25.48(cid:5)0.38 26.14(cid:5)0.39 26.67(cid:5)0.42 22.59(cid:5)0.30 23.30(cid:5)0.30 24.18(cid:5)0.32 25.35(cid:5)0.34 22.16(cid:5)0.24 22.64(cid:5)0.24 23.99(cid:5)0.26 27.04(cid:5)0.28
156............. 25.54(cid:5)0.39 25.96(cid:5)0.38 25.66(cid:5)0.40 25.83(cid:5)0.43 23.26(cid:5)0.34 23.37(cid:5)0.35 24.61(cid:5)0.37 24.57(cid:5)0.38 21.72(cid:5)0.19 21.85(cid:5)0.20 22.97(cid:5)0.20 25.39(cid:5)0.22
170............. 25.97(cid:5)0.40 25.02(cid:5)0.41 26.11(cid:5)0.41 25.92(cid:5)0.44 21.18(cid:5)0.23 21.64(cid:5)0.24 22.71(cid:5)0.26 23.84(cid:5)0.27 19.85(cid:5)0.22 20.27(cid:5)0.24 21.60(cid:5)0.25 24.05(cid:5)0.27
189............. 26.01(cid:5)0.38 26.21(cid:5)0.39 26.47(cid:5)0.39 27.20(cid:5)0.41 24.02(cid:5)0.35 24.57(cid:5)0.38 25.09(cid:5)0.38 26.60(cid:5)0.39 22.25(cid:5)0.28 22.89(cid:5)0.30 24.84(cid:5)0.30 27.46(cid:5)0.32
192............. 25.56(cid:5)0.39 25.72(cid:5)0.40 25.91(cid:5)0.42 26.60(cid:5)0.44 22.20(cid:5)0.30 22.80(cid:5)0.30 23.76(cid:5)0.31 24.67(cid:5)0.32 21.81(cid:5)0.27 22.27(cid:5)0.28 24.01(cid:5)0.31 26.65(cid:5)0.33
201............. 25.77(cid:5)0.33 25.58(cid:5)0.35 25.52(cid:5)0.37 25.62(cid:5)0.38 ... ... ... ... 26.85(cid:5)0.37 27.34(cid:5)0.38 29.06(cid:5)0.38 30.58(cid:5)0.39
252............. 25.76(cid:5)0.35 26.29(cid:5)0.33 25.84(cid:5)0.34 26.12(cid:5)0.34 ... ... ... ... 24.62(cid:5)0.19 25.04(cid:5)0.20 26.49(cid:5)0.23 28.01(cid:5)0.26
257............. 26.68(cid:5)0.40 26.51(cid:5)0.40 27.01(cid:5)0.41 27.57(cid:5)0.42 23.27(cid:5)0.34 23.11(cid:5)0.34 23.37(cid:5)0.36 24.16(cid:5)0.36 22.81(cid:5)0.25 23.31(cid:5)0.26 25.06(cid:5)0.28 27.04(cid:5)0.30
266............. 24.92(cid:5)0.37 25.80(cid:5)0.38 25.94(cid:5)0.37 26.54(cid:5)0.40 21.35(cid:5)0.23 21.89(cid:5)0.23 22.64(cid:5)0.25 23.40(cid:5)0.27 21.91(cid:5)0.28 22.14(cid:5)0.28 23.94(cid:5)0.29 26.80(cid:5)0.30
511............. 24.73(cid:5)0.37 24.39(cid:5)0.37 24.61(cid:5)0.39 25.24(cid:5)0.40 22.17(cid:5)0.30 22.66(cid:5)0.30 23.99(cid:5)0.33 25.05(cid:5)0.34 21.58(cid:5)0.25 21.98(cid:5)0.26 23.41(cid:5)0.26 27.10(cid:5)0.29
613............. 24.43(cid:5)0.37 25.35(cid:5)0.37 26.01(cid:5)0.39 27.83(cid:5)0.40 22.50(cid:5)0.25 23.11(cid:5)0.26 24.02(cid:5)0.26 24.75(cid:5)0.27 22.91(cid:5)0.30 23.67(cid:5)0.30 25.77(cid:5)0.33 28.09(cid:5)0.34
Notes.—Col.(1):sourcenumber,asinTable1;cols.(2)Y(5):totalmagnitude(notcorrectedforGalacticextinction)ofthePSFcomponentintheHSTfiltersz, i,V,andB,respectively;cols.(6)Y(9):totalmagnitude(not
correctedforGalacticextinction)ofthe exponentialcomponentintheHSTfiltersz,i, V,andB,respectively;cols.(10)Y(13):totalmagnitude(notcorrectedforGalacticextinction)ofthedeVaucouleurscomponentintheHST
filtersz,i, V,andB,respectively.Errorsarequotedata68%ofdeclaredconfidencelevel(seeAppendixBfordetails).
102 BALLO ETAL. Vol. 667
covering an area of 0.1 deg2 centered on the CDF-N. The HK0 TABLE3
filtercoversboththeHandK0bandsinasinglefilter;itallowsa Two-dimensionalImageFittingMorphologicalParameters
greater depth but involves some loss of color information. HK0
Disk Bulge
datahavebeencollectedusingtheQUIRCcameraontheUniver-
sityofHawaii2.2mtelescope,witha3:60;3:60fieldofviewand ID Redshift r P.A.(deg) b/a r P.A.(deg) b/a
withanABmagnitudelimitacrossthefieldof22.1(ina90;90 d e
(1) (2) (3) (4) (5) (6) (7) (8)
fieldaroundtheCDF-Nthebandreachesalimitof22.8mag).
CDF-N
3. DATA ANALYSIS
114........ 0.679 ... ... ... 1.57 (cid:1)6.62 0.87
Inordertodisentanglethemaingalacticcomponents(nucleus,
141........ 0.747 6.38 (cid:1)20.54 0.99 8.61 (cid:1)19.36 0.95
bulge, and disk) for the AGNs in our sample, we adopt a two- 150........ 0.762 3.59 (cid:1)16.31 0.65 5.26 (cid:1)21.31 0.62
dimensional fitting approach, applied to the GOODS HSTACS 170........ 0.680 2.77 (cid:1)9.47 0.32 7.09 (cid:1)8.47 0.91
images.Inparticular,toseparateatypicallyfaintnucleusfromthe 194........ 0.555 0.39 (cid:1)41.96 0.93 1 (cid:1)43.96 0.99
surroundingbrightbulge,weneedtodetermineaccurateandquan- 222........ 0.857 70.09 49.34 0.52 11.51 48.85 0.57
titativemorphologicalinformation.Ithasbeenshownthatmod- 243........ 0.961 1.38 58.78 0.77 4.01 60.30 0.80
elingintwodimensionsallowsabetterestimateoftheparameter 285........ 0.955 1.05 42.38 0.84 6 41.38 0.86
303........ 0.678 2.08 58.11 0.43 3.46 59.00 0.53
values in a bulge-disk decomposition (e.g., Byun & Freeman
323........ 0.514 3.19 (cid:1)86.18 0.81 4.09 (cid:1)88.77 0.76
1995;Wadadekaretal.1999).Toperformthefitweusethetwo-
368........ 0.935 ... ... ... 1.86 ...79.85 0.68
dimensionalimagedecompositionprogramGALFIT(Pengetal.
404........ 0.978 10.27 (cid:1)0.79 0.40 10.60 (cid:1)2.79 0.50
2002).Agalaxymodelisapplied,composedbyabulge,adisk,
412........ 0.474 0.51 (cid:1)54.11 0.35 0.81 (cid:1)56.33 0.31
andanuclearsource.Thedetailsoftheprocedure,aswellashow 439........ 0.839 3.01 84.41 0.79 3.90 83.90 0.86
weestimatedtheerrorsassociatedwiththemagnitudesofthedif- 451........ 0.838 1.54 20.62 0.48 2.36 19 0.52
ferentcomponents,arepresentedinAppendixB.Herewewantto
stressthatinoursurfacephotometrydecompositionwetakead- CDF-S
vantage of imagesin four different bands,in which the compo-
34.......... 0.839 1.28 (cid:1)7.22 0.48 4.59 (cid:1)6.22 0.46
nents of the host galaxy have a different relative importance.
40.......... 0.668 0.24 (cid:1)43.84 0.85 0.97 (cid:1)56.30 0.87
Results for the 34 sources analyzed are reported in Table 2 42.......... 0.734 ... ... ... 1.40 (cid:1)20.30 0.55
(magnitudesofthenucleusincols.[2]Y[5];magnitudesofthe 44.......... 0.734 1.37 (cid:1)2.07 0.68 1.32 (cid:1)2.70 0.67
diskincols.[6]Y[9];andmagnitudesofthebulgecomponentin 47.......... 0.733 0.62 25.96 0.86 1.27 36.17 0.96
cols. [10]Y[13]) and Table 3 (the host galaxy morphological 48.......... 0.534 10.00 48.40 0.82 10.23 62.10 0.82
parameters, i.e., scale length, position angle, and ratio of the 51.......... 0.670 1.21 (cid:1)57.39 0.80 0.64 (cid:1)51.41 0.66
semiminoraxistothesemimajoraxisforthediskaregivenin 52.......... 0.569 0.81 (cid:1)55.89 0.80 2.40 (cid:1)53.23 0.77
cols.[3]Y[5]andforthebulgeincols.[6]Y[8]). 151........ 0.604 1 (cid:1)69.09 0.28 2.37 (cid:1)70.40 0.26
156........ 0.545 4.95 (cid:1)16.24 0.79 5.41 (cid:1)14.24 0.76
InFigure4aweshowasanexampletheresultofthedecom-
170........ 0.664 1.58 33.21 0.52 4.56 32.91 0.53
position in a typical case (ID 34, CDF-S; z¼0:839). Similar
189........ 0.734 4.08 (cid:1)56.78 0.30 3.27 (cid:1)54.78 0.32
imagesforalltheanalyzedsourcesarepresentedintheelectronic
192........ 0.735 1.28 (cid:1)19.12 0.50 2.50 17.88 0.52
edition. The residuals after subtracting the final model (bottom 201........ 0.679 ... ... ... 1.20 21.36 0.33
panels) from the original images (top panels) in the four bands 252........ 0.481 ... ... ... 0.45 (cid:1)27.36 0.60
showthattheobjectiswellmodeled,apartfromtheresidualstrac- 257........ 0.549 2.21 3.38 0.31 2.12 3.27 0.27
ingthespiralarms(neveraccountedforintheappliedgalaxy 266........ 0.735 3.79 (cid:1)21.12 0.26 2.95 (cid:1)20.80 0.27
model)andsomeparticularlyintensespotsofemission. 511........ 0.668 4.78 16.97 0.93 5.14 18.97 0.90
Sincetheanalysisiscarriedoutseparatelyinthefourbands, 613........ 0.910 4.29 43.99 0.44 6.39 44.59 0.57
noaprioriconstraintisimposedonthemeasuredspectralenergy
Notes.—Col.(1):sourcenumber,asinTable1;col.(2):redshiftfortheop-
distributionsfortheindividualcomponents:bulge,disk,andnu- ticalcounterpart,asinTable1;cols.(3)Y(5):scalelength,positionangle,andsemi-
cleus.Itisworthrecallingthatreddeningmaysignificantlyaffect minoraxistosemimajoraxisratiooftheexponentialdisk;cols.(6)Y(8):scalelength,
theobservedSEDs.IntrinsicnuclearemissionintheUVandop- positionangle,andsemiminoraxistosemimajoraxisratioofthedeVaucouleurs
law.
ticalrangesmaybealteredbydustabsorptionfromcircumnuclear
and/ormorediffusecomponent(s).Thelatterisalsorelevantfor
thegalacticcomponents,particularlyforthedisk,whichiscom- elements in the interstellar gas and Yis the fraction by mass of
posedbyyoungerandbluerstars. helium(thesolarvaluesareZ ¼0:02andY ¼0:21).Forboth
(cid:3) (cid:3)
Bearingthisinmind,asafirsttestofthegoodnessofouranal- metal contents, integrated spectra of SSP of different ages have
ysiswecomparetheresultingSEDswithsuitabletemplates.SED beencomparedwiththemeanempiricalspectrum,findingtheage
templates for the bulge have been derived using a set of single thatprovidesthebestagreement:10GyrforZ ¼0:05,and11Gyr
stellarpopulation(SSP)SEDs.9FromthissetofSEDsweselecta forZ ¼0:02.Forthetwometallicities,havingfixedtheepochof
templaterepresentingthe‘‘typical’’ellipticalgalaxyatz(cid:4)0,by formation,wecomputetheintegratedSSPspectrumattheredshift
comparison with a mean local spectrum (obtained from the ofeachanalyzedsource.Whileforthebulgecomponentweas-
observedonesof NGC1399andNGC1404;A.Bressan2005, sumedthatstarsformedinasingleburst,fortheSEDsofthedisk
privatecommunication).Totakeintoaccountthewell-known componentweassumedacontinuousstarformationduringitslife.
metallicity-agedegeneracy,weassumetwoinitialchemicalcom- TheSSPsusedarethesameasforthebulge.Finally,tocheckthe
positions of the evolutionary sequences: [Z ¼0:02, Y ¼0:28], nuclear optical SED, we adopt the QSO template spectrum of
and[Z ¼0:05,Y ¼0:352],whereZisthemassfractionofheavy Cristiani&Vio(1990)downto5388,modifiedasdescribedby
Cristiani et al. (2004) and Monaco & Fontanot (2005) and ex-
9 Availableathttp://web.pd.astro.it/granato/grasil/SSP/ssp.html;seealsoSilva trapolatedto3008using f(cid:2) /(cid:2)(cid:1)1:75(followingRisaliti&Elvis
etal.(1998). 2004).
No. 1, 2007 M AND EDDINGTON RATIOS OFAGNs AT 0.4 < z < 1 103
BH
Fig.4.—Resultoftheanalysisforatypicalcase[ID34,CDF-S;z¼0:839].(a)Originalimagesinthefourbands(toppanels)andresidualsaftersubtractingthefinal
modelfromtheoriginalimages(bottompanels;seex3andAppendixB).(b)Leftpanel:Fitofthetemplates(bulge,dashedline;disk,dottedline;nucleus,solidline)tothe
decomposedopticalmagnitudesforthedifferentcomponents(bulge,squares;disk,stars;andnucleus,circles),andcomparisonofthesumofthetemplates(dot-dashed
line)withthefluxesobservedfromthewholegalaxyinalltheavailablebands(diamonds);acontributionfromacircumnucleartorus(long-dashedline),adaptedfromthe
meanSEDofatypicalSeyfert1galaxyreportedinGranato&Danese[1994]),isassumedtoaccountforSpitzerdata.Rightpanel:FitoftheQSOtemplate(solidline)to
thenuclearSED(opticalmagnitudes,circles;andX-rayflux,squares;grayareasrepresenttheuncertaintyintheopticalemission,estimatedasdescribedinx4.2,andthe
consequentuncertaintyintheUVrange).[SeetheelectroniceditionoftheJournalforacolorversionofthisfigure.]
InFigure 4b(leftpanel) we showthecomparisonofthede- remaining10casestheemissionintheVandespeciallyBbands
composed SEDs with the three templates and the magnitudes islower thanexpectedfromtheSEDnormalizedtotheiandz
forthewholegalaxyinalltheavailablebandsforagenericcase bands.Thepresenceofsignificantobscurationaroundthesenuclei
(ID34,CDF-S;z¼0:839).Thesamecomparisonforthewhole isconfirmedbytheirhighcolumndensity,N (cid:6)1022 cm(cid:1)2,in-
H
sampleisshownintheelectronicedition.Forthebulgecompo- ferredfromtheirX-rayemission.
nent the observed SEDs are in good agreement with the tem- Fluxesfromthedecompositionandtemplateshavealsobeen
plate((cid:3)2perdegreeoffreedombetween0.8Y0.9and1.3Y1.5). compared with themagnitudes for thewhole galaxy recovered
We stress that the bulge component is expected to be less af- fromtheGOODScatalog,aswellaswiththemagnitudesinthe
fectedbyabsorption. Even forthediskcomponent verygood IR(includingdatafromSpitzer)andUband,whenavailable.For
agreementisgenerally found,withoutinvokinglargecorrection the U-band and Spitzer data the angular resolution is not good
forabsorption. enoughtoletustomakeamorphologicaldecomposition.Never-
Concerning the nuclei, the agreement of the observed SEDs theless,wecanobtainimportantindicationsbycomparingtheob-
withthetemplateisgoodfor70%oftheanalyzedobjects;inthe servedtotalfluxeswiththesumofthetemplatesofbulge,disk,
104 BALLO ETAL. Vol. 667
3.1.Host-dominated and Nucleus-dominated Sources
Whentheopticalimagesaredominatedatallwavelengthsby
oneofthegalaxycomponents(nucleus,bulge,ordisk),theother
componentscannotbetightlyconstrained.
InsourcesdominatedbytheAGN(twoobjectsinthepresent
sample),wecanonlyputupperlimitstothehostcomponentby
minimizingthenuclearcontribution(whichiswellconstrained).
Weputathresholdonthenucleus-to-totalluminosityratioN/T
(reportedinTable4)inthezbandofN/T(z)¼0:2asafiducial
valuetoidentifythegalaxiesaffectedbythisproblem.Forthetwo
analyzedsourcessatisfyingthiscriterion(ID42,CDF-S,N/T(z)¼
0:329; and ID 201, CDF-S, N/T(z)¼0:293),we proceed as
follows.
1. WeassumefortheQSOtemplateanormalization2(cid:4)lower
thanthebestfit(wheretheuncertaintiesareevaluatedasdescribed
inAppendixB),determiningaminimumvalueforthenuclear
magnitudesinthefourbands.
2. Assumingthesenuclearmagnitudes,werescalethebulge
component10untiltheobservedvalueofthetotalfluxesisreached.
3. Finally, we compare the new galaxy reconstruction (i.e.,
thesumofthetemplatesof bulgeandnucleusrescaled)withthe
emissionintheIRbands,checkingthatthenewestimatedoesnot
Fig.5.—AveragesurfacebrightnesswithintheeffectiveradiusintheV-band overpredict(atmorethan2(cid:4)level)theemissionatwavelengths
(Johnsonmagnitude)vs.theeffectiveradius.Thesurfacebrightnessforeach greaterthan1(cid:1)m.
bulgehostinganX-ray-selectedAGNs(triangles)hasbeenderivedfromthe
parametersreportedinTable2andTable3(withaK-correctionappliedtoconvert Forbothsourceswefindthatthebulgeluminositycanincrease
theobservedi-bandABmagnitudesinrest-frameV-bandJohnsonmagnitudes). uptoafactorof10withrespecttotheresultofthedecomposition.
Thedistributionfoundfortheanalyzedsourcesisingoodagreementwiththatof
Weconsiderthesevaluesrobustupperlimits.
localellipticalgalaxiesandbulgesstudiedbyBenderetal.(1992)convertedin
Ontheotherhand,whentheopticalemissionisdominatedby
theVbandassumingB(cid:1)V ¼0:96andcorrectedforthedifferentcosmology
adopted(crossesinthefigure).ThesameregionintheSB-r planeisoccupiedby thehostgalaxycomponents(bulgeand/ordisk,sixobjects),the
e e
the18bulgesofSeyfert1andSeyfert1.5galaxiesobservedintheV-bandby nuclearcontributionprovidedbyGALFITcouldbealowerlimit
Granatoetal.(1993),correctedforthedifferentcosmologyadopted(dots).We totheactualone.Wereanalyzedseparatelythesixsourceswith
alsofindagoodagreementwiththedistributionreportedbyFasanoetal.(1998)for
nucleus-to-totalluminosityratiointheVbandN/T(V)<0:05
asampleof23early-typegalaxieswithspectroscopicredshiftzP3:4,withK-and
evolutionarycorrectionsapplied(seetheirFig.6)andcorrectedforthedifferent (seeTable4).
cosmologyadopted(opensquares).
1. We assume for bulge and disk templates a normalization
2(cid:4)lowerthanthebestfit(wheretheuncertaintiesareevaluated
andnucleus,normalizedtothedecomposedmagnitudes.Inpar- asdescribedinAppendixB),determiningaminimumvaluefor
ticular, we are abletoreproduce the Spitzer data byassuming a theirmagnitudesinthefourbands.
contributionfromacircumnucleartorus,asobservedinatypical 2. Upperlimitstothenuclearmagnitudesarethencalculated
Seyfert1galaxy(seeGranato&Danese1994). imposingthatthetotal(hostplusnucleus)valuesareequaltothe
TheconstraintsderivedfromtheobservedIRemissionforthe observedones.
fluxexpectedonthebasisofthisreconstructionareparticularly 3. WecheckthatthenewestimateofthenucleusintheUband
importantwhenthenuclearcomponentisdominantandtendsto isnothigher(atmorethan2(cid:4)level)thantheobservedflux.
overwhelmtheemissionfromthehostgalaxy:inthesecasesthe
Again,theresultsofthisprocedureareconsideredrobustupper
magnitudesdeterminedforbulgeanddiskarenotcompletelyre-
limitstothenuclearluminosity.
liable,andthismayaffecttheBHmassdetermination(seex4.1).
Asdescribedinmoredetailinx3.1,insuchcaseswecanonly
4. RECOVERING THE NUCLEAR PROPERTIES
provide upper limits for the bulge magnitudes; constraints im-
posedbytheobservationsintheIRrangepreventusfromover- Disentanglingthedifferentgalacticcomponentsasdescribed
estimatingthisfaintercomponent. in x 3 and in Appendix B provides detailed information on the
The bulge component is relevant not only in the estimate of bulgeandnuclearluminosity.Thisinformationisrelevantinorder
thenuclearcontribution,butalsoindeterminingtheBHmasses tostudythenuclearactivityofthegalaxiesinoursample.Inx4.1
(seex4).Therefore,wecheckedthattherelationbetweentheef- wepresentourderivationoftheBHmass,whilethebolometric
fectiveradiusr andthesurfacebrightnesswithinit,SB ,iscon- luminosityisevaluatedfromopticalandX-raynuclearluminos-
e e
sistent with that derived for local samples. In particular, from itiesasdescribedinx4.2.
Figure5itisapparentthatthebulgesderivedthroughouranal-
4.1. Black Hole Masses
ysisaredistributedinther-SB planeasthesampleofnearby
e e
ellipticalgalaxiesandbulgesstudiedbyBenderetal.(1992).Itis Startingfromtheabsolutemagnitudesofthebulgecomponent,
interestingtonotethatthesameregionoftheplaneisoccupied weobtainanestimateofthemassofthecentralcompactobject,
bythebulgesoflocalSeyfertgalaxies,asdeterminedbyGranato
et al. (1993), as well as by a sample of early-type galaxies at
10 Wenotethatforboththesourcesreanalyzedthediskcomponentisnot
higherredshift(seeFasanoetal.1998). requestedinthefit.
No. 1, 2007 M AND EDDINGTON RATIOS OFAGNs AT 0.4 < z < 1 105
BH
TABLE4
RatiooftheDifferentComponentsMagnitudes,asObtainedfromtheTwo-dimensionalImageFitting
Bulge/Galaxy Nucleus/Bulge Nucleus/Total
ID Redshift z i V B z i V B z i V B
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)
CDF-N
114................ 0.679 1.000 1.000 1.000 1.000 0.349 0.396 1.739 25.26 0.115 0.124 0.241 0.325
141................ 0.747 0.739 0.675 0.636 0.234 0.029 0.045 0.133 1.986 0.020 0.028 0.068 0.194
150................ 0.762 0.666 0.643 0.428 0.022 0.040 0.041 0.132 3.631 0.024 0.025 0.048 0.065
170................ 0.680 0.747 0.712 0.560 0.101 0.023 0.025 0.052 0.643 0.016 0.017 0.027 0.054
194................ 0.555 0.413 0.245 0.200 0.055 0.010 0.018 0.038 0.501 0.004 0.004 0.007 0.025
222................ 0.857 0.546 0.447 0.242 0.072 0.063 0.091 0.305 1.809 0.031 0.036 0.060 0.093
243................ 0.961 0.476 0.386 0.227 0.077 0.078 0.245 0.972 2.323 0.033 0.074 0.133 0.116
285................ 0.955 0.714 0.705 0.605 0.097 0.030 0.055 0.229 6.742 0.020 0.035 0.098 0.221
303................ 0.678 0.610 0.667 0.518 0.107 0.066 0.065 0.354 6.362 0.036 0.038 0.118 0.224
323................ 0.514 0.870 0.846 0.768 0.285 0.194 0.218 0.967 11.805 0.112 0.119 0.230 0.303
368................ 0.935 1.000 1.000 1.000 1.000 0.286 0.336 0.257 10.365 0.100 0.112 0.093 0.313
404................ 0.978 0.565 0.515 0.441 0.083 0.084 0.177 0.383 1.905 0.041 0.072 0.112 0.107
412................ 0.474 0.309 0.287 0.214 0.029 0.298 0.774 1.676 18.345 0.072 0.133 0.173 0.205
439................ 0.839 0.602 0.560 0.436 0.037 0.050 0.153 0.495 7.399 0.027 0.068 0.131 0.151
451................ 0.838 0.847 0.756 0.715 0.391 0.033 0.056 0.254 2.254 0.026 0.038 0.118 0.242
CDF-S
34.................. 0.839 0.422 0.318 0.235 0.032 0.360 0.280 0.777 11.665 0.104 0.070 0.118 0.176
40.................. 0.668 0.734 0.753 0.516 0.229 0.049 0.045 0.156 1.057 0.032 0.031 0.065 0.140
42.................. 0.734 1.000 1.000 1.000 1.000 48.591 119.994 511.588 5323.043 0.329 0.331 0.333 0.333
44.................. 0.734 0.454 0.523 0.322 0.070 0.064 0.098 0.384 4.169 0.027 0.044 0.090 0.155
47.................. 0.733 0.516 0.495 0.436 0.092 0.231 0.308 0.895 6.026 0.088 0.105 0.180 0.209
48.................. 0.534 0.766 0.802 0.732 0.407 0.066 0.085 0.166 1.977 0.044 0.056 0.089 0.236
51.................. 0.670 0.622 0.641 0.488 0.445 0.191 0.265 0.920 1.570 0.087 0.113 0.191 0.226
52.................. 0.569 0.231 0.170 0.114 0.118 0.474 1.170 1.941 15.785 0.083 0.125 0.133 0.283
151................ 0.604 0.599 0.649 0.544 0.174 0.050 0.073 0.138 1.404 0.027 0.041 0.061 0.141
156................ 0.545 0.805 0.802 0.818 0.318 0.030 0.023 0.085 0.668 0.022 0.017 0.057 0.130
170................ 0.664 0.773 0.780 0.736 0.450 0.004 0.013 0.016 0.181 0.003 0.010 0.011 0.065
189................ 0.734 0.836 0.825 0.557 0.310 0.031 0.047 0.223 1.273 0.024 0.035 0.091 0.181
192................ 0.735 0.588 0.619 0.441 0.139 0.032 0.042 0.175 1.047 0.018 0.024 0.063 0.101
201................ 0.679 1.000 1.000 1.000 1.000 2.723 5.054 26.065 96.235 0.268 0.294 0.325 0.331
252................ 0.481 1.000 1.000 1.000 1.000 0.348 0.318 1.813 5.721 0.114 0.108 0.244 0.299
257................ 0.549 0.605 0.454 0.175 0.066 0.028 0.052 0.165 0.616 0.016 0.022 0.027 0.036
266................ 0.735 0.374 0.443 0.233 0.042 0.063 0.034 0.158 1.267 0.022 0.015 0.033 0.046
511................ 0.668 0.634 0.652 0.630 0.132 0.055 0.107 0.331 5.516 0.031 0.058 0.128 0.229
613................ 0.910 0.407 0.375 0.166 0.044 0.247 0.212 0.801 1.275 0.077 0.064 0.095 0.048
Notes.—Col.(1):sourcenumber,asinTable1;col.(2):redshiftfortheopticalcounterpart,asinTable1;cols.(3)Y(6):bulge-to-galaxyratiointhefourbands;
cols.(7)Y(10):nucleus-to-bulgeratiointhefourbands;cols.(11)Y(14):nucleus-to-totalratiointhefourbands.
exploitingtheobservedlocalrelationshipbetweenBHmassand thatof localquiescentgalaxies.Thereareclaimsthatthecorre-
bulge component luminosity. Several versions of this relation lationbetweenBHmassandbulgevelocitydispersioncouldbe
havebeenproposedwiththebulgeluminosityevaluatedatelec- subjecttoacosmicevolution(Wooetal.2006);however,sucha
tromagnetic bandsrangingfromBtoK(see,e.g., Kormendy& behaviorwouldproduceBHmassestimatesslightlyhigherthan
Gebhardt2001;McLure&Dunlop2002;Marconi&Hunt2003). thatpresentedinthefollowing.Ontheotherhand,itishardto
InordertocomputetheBHmass,weassumethat(1)inthis imagine how a significant independent evolution can lead to a
relationtheabsolutemagnitudeofthebulgestrictlymirrorsthe M -M relationwithascatterassmallasthatreportede.g.,
bulge BH
massinoldstars,M ,whichisthequantityprimarilyrelated byFerrarese&Ford(2005).
bulge
totheBHmass;and(2)theM -M relationisimprintedat The relation with the total R-band magnitude of the bulge
bulge BH
highredshift,drivingthemainepisodeofaccretion. reportedinMcLure&Dunlop(2002)forasampleof20inac-
The latter hypothesis is supported by the findings of Peng tiveE-typegalaxiesatz(cid:4)0andconvertedtoH ¼70kms(cid:1)1
0
etal.(2006),whoshowthattheM -M relationsforfiveAGNs Mpc(cid:1)1reads
BH R
atz(cid:2)1arecompatiblewiththelocalrelation,oncepassiveevo-
(cid:1) (cid:2)
lutionofthestellarpopulationisallowedfor,andbyMcLure& log MBH ¼(cid:1)0:50((cid:5)0:03)M (cid:1)2:69((cid:5)0:72); ð1Þ
Dunlop(2002),who,analyzingwiththesametechniqueasam- M R
(cid:3)
pleof 72activegalaxies(SeyfertgalaxiesandQSOs)atzP0:5,
demonstrate thatAGNhostgalaxies attheseredshifts followa withascatterof(cid:1)log(M )¼0:33.TheM -M relation
BH bulge BH
relationbetweenBHmassandbulgeluminosityconsistentwith reportedbyBettonietal.(2003)intheirequation(1)forasample
106 BALLO ETAL. Vol. 667
of nearby inactive ellipticals is in good agreement with equa- AGNsatlowredshiftspanthewholerangeinmass,whileatthe
tion(1),oncethedifferentcosmologyistakenintoaccount(even upperendoftheredshiftdistributiononlylarge(M >107M )
BH (cid:3)
ifinthissecondcasethescatterislarger,0.39dex).Itisworthnot- BHmassesarefound(seeFig.6,toppanels).Noobviousselec-
ingthatequation(1)hasbeenderivedusingB-andV-bandmag- tioneffects,inthisregard,havebeenidentified.Suchabehavior
nitudes,translatedtoRbandassumingaveragecolors(B(cid:1)R)¼ seemstobeanintrinsicpropertyofthesample.Wedonotsee
1:57and(V (cid:1)R)¼0:61.The relation reported by Marconi& anycorrelationbetweentheestimatedbulgeluminosityandthe
Hunt(2003)exploitstheK-bandmagnitudesandonaveragepre- X-rayluminosity.Asaconsequence,nocorrelationisfoundalso
dictsBHmasseshigherbyabout0.3dexatfixedluminosity.The betweenBHmassandX-rayluminosity.
difference could be ascribed to the uncertainty in evaluating
thebulgecomponentofspiralgalaxiesoftheobservedsample 4.2.Nuclear Bolometric Luminosities
(Shankaretal.2004).TherelationshipestimatedbyKormendy
Inordertogaininsightintotheaccretionratespoweringthese
&Gebhardt(2001)using B-bandbulgeluminositiesyieldsBH
sources,weneedtoinvestigatetheirnuclearbolometricluminos-
masseslargeratmostbyabout0.2dexthanthosepredictedon
ity.Wecomparethenuclearemission(i.e.,theX-rayflux,totally
the basis of equation (1). On the other hand, Bernardi et al.
ascribedtotheAGN,andtheopticalnuclearmagnitudes)toSEDs
(2007)andTundoetal.(2006)havesuggestedthattheM -L
BH of active nuclei with different X-rayYtoYoptical ratios. In these
relationisbiasedtowardpredictingmoremassiveblackholes
SEDs,thehigh-energyemissionisdescribedasapowerlawwith
foragivenluminosity.The intrinsic M -Lrelation proposed
BH photonindex(cid:2).FortheopticalbandsweadopttheQSOtemplate
byBernardietal.(2007)intherangeofluminositiesofinterest
spectrumdescribedinx3.
forthepresentworkyieldsBHmassesthatareveryclosetothe
TheseSEDs(describingtheemissionofatype1AGN)must
correspondingonesofequation(1)((cid:1)logM (cid:2)0:2).
BH
becomparedwiththeintrinsicnuclearemission,whichincase
Inthefollowingweconservativelyadopttherelationproposed
of absorbed sources could be very different from the observed
byMcLure&Dunlop(2002),whichyieldsthelowestmassesti-
one.TheproblemistackledstartingfromtheX-rayspectralanal-
mates.TheBHmassesquotedinthefollowingcouldbeafactorof
1.5Y2higher(and,correspondingly,theEddingtonratioslowerby ysisandassumingthepictureproposedbytheunifiedmodel:
the same factor), if the relationships proposed by Kormendy & 1. X-rayemission:
Gebhardt(2001)orbyMarconi&Hunt(2003)wereused.
(a) We de-absorb the X-ray flux, adopting for the CDF-S
Inordertoestimatetherest-frameR-bandmagnitudeatz(cid:4)0
sourcestheintrinsicN quotedbyTozzietal.(2006);sincethe
forthebulgesinoursample,westartedfromtheSSPSEDsnor- H
analysisofCDF-NX-rayemission(Alexanderetal.2003)does
malizedasdescribedinx3(K-correction)andcomputedtheirpas-
notinclude an intrinsic absorption,we derive it from thehard-
siveevolutionuptothepresentepoch.11TheR-bandmagnitudes
nessratiosandredshifts,assumingameanphotonindex(cid:2)¼1:8.
obtainedbyusingthetwometallicitiesintroducedinx3arevery
AsshowninTable5,onlyoneobjectofthesampleexhibitsahy-
similar,within0.1magforallthesources.ThemeanoftheR-band
drogencolumndensityN ’1:5;1024 cm(cid:1)2(Compton-thick
magnitudes,aswellastheBHmassesobtainedfromequation(1), H
candidate).
arereportedinTable5.Forsourcesdominatedbythenuclear
(b) WerecovertheintrinsicX-rayluminositynormalizinga
componentorbythehostgalaxy,thesamefithasbeenalsocar-
power-lawspectrumhavingthesameX-rayphotonindexofthe
riedoutassumingforthebulgethemagnitudesrecoveredasde-
source(fortheCDF-S)orwith(cid:2)fixedto1.8(fortheCDF-N)so
scribedinx3.1.Thecorrespondingupperorlowerlimittothe
thatitmatchestheintrinsicX-rayflux.
massofthecentralBHisreportedasasecondlineinTable5.
ErrorsfortheR-bandmagnitudeofthebulgecomponentare 2. Opticalbands:
evaluatedbyquadraticallysummingtwodifferentcontributions:
(a) WecomparetheQSOtemplatespectrumwiththeoptical
1. The uncertainties associated with the decomposed mag- nuclearmagnitudes,computing
nitudespropagateontothebest-fitnormalizationoftheelliptical
steomurpclea,tewaedroeppteeadtitnhecofimtpchuatinngginthgetRhe-bnaonrdmmalaigzantiitoundeosf:tfhoereteamch- (cid:3)2 ¼NXbands(cid:3)Fobs;j(cid:1)b;Ftempl;j(cid:4)2;
(cid:4)
plate until (cid:1)(cid:3)2 ¼1, and we compute the R-band magnitudes j¼1 j
corresponding to the minimum and maximum values of the
normalization. wherebisanormalizationconstant,whileF ,F ,and(cid:4)
obs;j templ;j j
2. The difference between the R-band magnitudes found by aretheobservedandtemplatefluxes,andtheuncertaintyofthe
usingfortheSSPstwodifferentmetallicities(seex3)isassumed former,intheopticalbandj,respectively.
asanestimateoftheerrorinducedbyselectingthatparticulartem- (b) NormalizingtheQSOtemplatewiththevalueofbcorre-
plates to represent a local inactive galaxy (i.e., by choosing the spondingtotheminimumvaluefor(cid:3)2,weobtaintheopticalcon-
twoabove-mentionedpairsage/metallicity). tributiontothebolometricluminosity.
(c) IfN >1022cm(cid:1)2(thisisthecaseofabouttwo-thirdsof
WhenpropagatedtoyieldtheuncertaintiesoftheBHmasses, H
theanalyzedsources),thepresenceofdustinthecentralregions
thecontributionduetotheerrorinM isalwaysnegligiblewith
R couldaffectseriouslyourestimateofnuclearmagnitudes.Inthis
respecttothescatterintherelationdescribedbyequation(1).
case,weprefertoignorethefluxesinBandVband(wherethe
Themassesaredistributedovertwodecades,2;106(cid:2)M (cid:2)
BH effectsoftheabsorptionaremoresevere),ratherthantoassumea
2:5;108 M ; only 3 out of 34 objects have M (cid:2)106 M .
(cid:3) BH (cid:3) quitearbitrarycorrectionfactor.So,onlytheiandzmagnitudes
areconsideredinthefit.
11 Asacheck,weevaluatedalsotheBHmassesobtainedfromtherelationfor 3. Bolometric properties: Connecting the power-law spec-
AGNsathigherredshift(seeTable3inMcLure&Dunlop2002)usingtherest-
trumandtheQSOtemplatenormalizedasdescribedbefore,we
frameR-bandmagnitudeattheredshiftofeachsource(i.e.,withoutevolution);
recovertheX-rayYtoYopticalratio,thebolometricluminosityof
wefoundasystematicshiftoftheorderof+0.18dexwithrespecttothevalues
reportedinTable5. theAGNandthehardX-raybolometriccorrection.