Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert Galaxies: II. Warm Absorber dynamics and feedback to galaxies

1.7 MB·

by  Sibasish Laha

Mon.Not.R.Astron.Soc.000,000–000(0000) Printed26January2016 (MNLATEXstylefilev2.2)
Warm Absorbers in X-rays (WAX), a comprehensive high resolution
grating spectral study of a sample of Seyfert Galaxies:
II. Warm Absorber dynamics and feedback to galaxies.
6
1
0
2 Sibasish Laha1⋆, Matteo Guainazzi2,3†‡, Susmita Chakravorty4, Gulab C. Dewangan5,

n 5
and, Ajit K. Kembhavi .
a
J 1SchoolofMathematicsandPhysics,TheQueen’sUniversityofBelfast,Belfast,BT71NN,UnitedKingdom.
4 2EuropeanSpaceAstronomyCentreofESA,POBox78,VillanuevadelaCanada,28691,Madrid,Spain.
2 3InstituteofSpaceandAstronauticalScience,3-1-1Yoshinodai,Chuo-ku,Sagamihara,Kanagawa,Japan.
4Laboratoired’Astrophysique,UniversiteJosephFourier,CNRSUMR5571,Grenoble,France.
] 5InterUniversityCentreforAstronomyandAstrophysics,Postbag4,Ganeshkhind,Pune,India.
A
G
26January2016
.
h
p
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ABSTRACT
o
r
t This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried
s
a out using high resolution grating spectral data from XMM-Newton satellite (WAX-I). Here
[ wediscusstheglobaldynamicalpropertiesaswellastheenergeticsoftheWA components
detectedintheWAXsample.TheslopeofWAdensityprofile(n∝r−α)estimatedfromthe
1
v linearregressionslopeofionizationparameterξandcolumndensityNHintheWAXsampleis
9 α=1.236±0.034.WefindthattheWAcloudspossiblyoriginateasaresultofphoto-ionised
6 evaporation from the inner edge of the torus (torus wind). They can also originate in the
3 coolingfrontoftheshockgeneratedbyfasteraccretiondiskoutflows,theultra-fastoutflows
6 (UFO),impingingontotheinterstellarmediumorthetorus.Theaccelerationmechanismfor
0 theWAiscomplexandneitherradiativelydrivenwindnorMHDdrivenwindscenarioalone
1. candescribetheoutflowacceleration.However,wefindthatradiativeforcesplayasignificant
0 roleinacceleratingtheWAthroughthesoftX-rayabsorptionlines,andalsowithdustopacity.
6 Given the large uncertaintiesin the distance and volume filling factor estimates of the WA,
˙
1 weconcludethatthekineticluminosityEK ofWAmaysometimesbelargeenoughtoyield
: significant feedback to the host galaxy. We find that the lowest ionisation states carry the
v
i maximummassoutflow,andthesourceswithhigherFeMUTAabsorption(15−17A˚)have
X
moremassoutflowrates.
r
a Keywords: galaxies:Seyfert,X-rays:galaxies,quasars:individual:
1 INTRODUCTION Chandra and XMM-Newton observatories. Thesemass outflows
may provide us with clues about how the SMBHs interact with
Activegalacticnuclei(AGN)aresourcesofhugeenergycontribut-
thehostgalaxyandhowtheyco-evolveoncosmictimescale.The
ingtopanchromaticspectrarangingfromradiowavelengthstohard
mainquestioniswhetherthemassoutflowsprovideenoughmate-
X-raysandGammarays.Themostcommonlyacceptedpictureof
rialfeedbacktothehostgalaxytosolvesomeofthecosmological
anAGNisasupermassiveblackhole(SMBH)atthecentre,accret-
puzzles,e.g.,chemicalenrichmentofthehostgalaxy,therelation
ingmatterintheformofadisk.Apartfromemittinghugeluminos-
betweenthemassofSMBHandthestellarvelocitydispersion,the
ity,AGNalsoshowspectroscopicsignaturesincludingabsorption
formation of large scale structures in the early universe, the dis-
featuresintheUVandX-raybandsuggestingthepresenceofmass
crepancy between visible to baryonic mass ratio in the Universe
outflowsintheformofionisedclouds.Thesemassoutflowshave
(Baloghetal. 2001). The underlying physics of structure forma-
beenintheeyeofactiveresearchforthelastoneandahalfdecade
tionisthatthebaryonsneedtocoolbeforetheycangravitationally
after the advent of high resolution grating spectrometeres aboard
collapse,otherwisethethermal/radiativeforcescanbalancethein-
wardgravitationalpullandstopthecondensation.Evenwhenone
includesradiativecoolinginthecosmologicalmodels,theobserved
⋆ [email protected],[email protected] fractionofvisibletobaryonicmassisnotobtained.Thispointsto
† [email protected]
someexternalheating(shock/outflow/external-radiation)actingon
‡ [email protected]
2 Laha et al.
thebaryonicmatterwhichpreventsitfromcooling. Theoutflows anglewithinthegalaxy.Moreover,jetsoccurinjust10%oftheto-
fromAGNcouldbethissourceofexternalheating. talAGNinnearbyuniverse,whichsuggeststhatamoreuniversal
The ionised absorbers, popularly known as the warm ab- phenomemonshouldberesponsibleforAGN-Galaxyfeedback.
sorbers (WA) have been studied extensively, both for individual InthisworkwecalculatetheWAdynamicsusingtheresults
bright sources like NGC 5548, Mrk 509, NGC 3783, Mrk 766, from a previous paper of this series Lahaetal. (2014) (hereafter
NGC4051,MCG-6-30-15,Mrk704,NGC5548etc.(Kaastraetal. L1).Wehavesystematicallyandhomogeneously analysedasam-
2012; Crenshawetal. 2003; Krongoldetal. 2008; Pontietal. pleofSeyfert1galaxiesandcharacterisedtheirWAproperties.The
2006; Turneretal. 2004; Lahaetal. 2011; Kaastraetal. 2002) WAXsampleisasubsampleoftheCAIXA(CatalogueofAGNin
as well as in samples of AGN (Goffordetal. 2015a; Lahaetal. XMM Archive) sample which consists all radio quiet X-ray un-
2014;Tombesietal.2013;Winteretal.2012;Tombesietal.2010; obscuredAGNwhichwereobservedbyXMM-Newton by2008.
McKernanetal.2007;Blustinetal.2005).However,therehasnot This list was cross-correlated with the RXTE X-ray sky survey
beenaconclusiveagreementontheoriginoftheseoutflows,what (Revnivtsevetal.2004)whereby onlythose sourceswerekept in
drives these outflows and how the feedback from these outflows thefinallistwhichhadacountrateofatleast1counts−1.Thefinal
interactwiththehost-galaxy. WAXlisthas26sources.ThebroadbandEPIC-pnaswellashigh
The first compilation of the existing WA studies using grat- resolutionRGSdataforeachsourcewereanalysedtoascertainthe
ingdatawascarriedoutbyBlustinetal.(2005)wheretheauthors broadbandcontinuumaswellastheWAproperties.Simultaneous
foundthatthekineticluminositiesoftheWAarelessthan1%of Optical Monitor (OM) data were used to constrain the UV SED
bolometric luminosity of the source. The authors concluded that whichiscrucial fordetermining theWAproperties (seefor e.g.,
theWAmaynotprovidesufficientfeedbacktothehostgalaxyto Lahaetal.2013;Reevesetal.2013;Leeetal.2013).
haveanyimpactonitsevolution.However,theauthorsnotedthat Out of the 26 X-raytype 1 AGN,17 (65%) sources haveat
thevolumefillingfactorcouldplayacrucialroleincalculatingout- leastonewarmabsorbercomponent.TheWAXsampleprobesthe
flowestimates.Theauthorsalsofoundthatthemassoutflowrates columndensityofNH =1020−23.5 cm−2,ionisationparameterof
oftheWAexceedthemassaccretionratesoftheSMBHbyafactor logξ = −1to3.2, andoutflow velocityof0−104 kms−1.The
ofseveraldecades.TheyattributedtheoriginoftheWAcloudsto ionisation parameter isdefined as ξ = Lion/ner2 where Lion is
‘toruswind’,wherethetorusisaneutralobscuringringlikestruc- the ionising luminosity of the source in the energy band 1-1000
turearoundtheSMBH(Urry&Padovani1995). McKernanetal. Ryd, ne istheelectron density of thecloud and r isthedistance
(2007)studiedtheWAcharacteristicsinasampleofSeyfertgalax- ofthecloudfromthecentralengine.Atotalof33WAcomponents
ies using high resolution Chandra data. The authors found that were detected and the ionisation parameter and the column den-
the mass outflow rates and kinetic energy estimates are crucially sityweremeasuredwithover3σaccuracyinmostcases.Forafew
dependent on theunknown volume fillingfactor of the warmab- WAcomponents,thevelocitycouldnotbeconstrained.Wefound
sorber clouds. The mass outflow rates of the WA calculated by that the WA parameters show no correlation among themselves,
themcouldequalthemassaccretionrateoftheSMBHevenfora withtheexceptionoftheionizationparameterversuscolumnden-
volumefillingfactorofjust1%.Hence,thewarmabsorberscould sity.Theshallowslopeofthe logξversuslogvoutlinearregression
be regarded as a potential feedback source. A combined UV ab- 0.12±0.03isinconsistentwiththescalinglawspredictedbyradi-
sorberandX-rayWAstudyforasampleofsixbrightSeyfertgalax- ationormagneto-hydrodynamic-drivenwinds.Ourresultssuggest
ieswerecarriedoutbyCrenshaw&Kraemer(2012).Theauthors alsothatWAandUltraFastOutflows(UFOs)donotrepresentex-
found that even for moderately luminous sources, with bolomet- trememanifestationofthesameastrophysicalsystem.Wetestthese
ricluminosityL ∼1043−45ergs−1,theionisedoutflows(WA resultsfurtherinourpresentworkusingthedynamicalparameters
bol
andUVabsorberscombined)canprovidesufficientfeedbacktothe oftheWA.
hostgalaxies.Theauthorshaveobtainedwellconstrainedmeasure- Inthispaperweaimataddressingthefollowingquestions:
mentsonthedistancesoftheabsorbersusingtheabsorptionfrom
• AretheWAandtheUFOssametypeofoutflows,anddothey
the excited states (in UV) and absorption variability (in X-rays).
havesimilarorigin?
ThreeoutofsixsourcesintheirsampleexhibitedWAwithkinetic
• TheestimationofWAkineticenergyoutflowrate.Weusethe
luminositiesintherange0.5−5%ofL .Atleastfiveofthesix
bol comparisonofthequantityagainsttheAGNbolometricluminosity
Seyfert1salsohavemassoutflow ratesthatare10−1000 times
toestimatetheAGNfeedbacktothehostgalaxy.
the mass accretion rates needed to generate their observed lumi-
• Is there any correlation between WA absorbed flux and the
nosities.TheseresultspointtothefactthattheAGNWAhavethe
ionisingluminosityortheX-rayluminosity?
potentialtodeliversignificantfeedbacktothehostgalaxy.
• Whatistheoutflow/launchingmechanismofWAandhowdo
MorerecentstudiescarriedoutbyTombesietal.(2013)and
theycomparewiththeUFOsandUVabsorbers?
Goffordetal. (2015a) involving the ultra-fast-outflows (UFOs), • WhatisthedensityprofileoftheWAclouds?
whicharehighionisationandhighvelocityoutflowsinAGN,found
thattheUFOsaremoreimportantintermsoffeedbackcomparedto Thispaperisorganisedasfollows:Section2describesthecal-
thewarmabsorbers.TheUFOsyieldakineticluminositywhichis culationsandtheunderlyingassumptionsconsideredwhilederiv-
comparabletothebolometricluminosityofthesource.Theorigin ingthedynamicalparametersofWA.Section3describesthemeth-
of theUFOarepresumed tobefromtheaccretiondiskwinds. A odsofcorrelationsemployedinthiswork.Section4discussesthe
similarstudybyKingetal.(2013)carriedoutcomparingtheWA, resultsfollowedbyconclusion.
UFOandjetpropertiesfromthepublishedliteraturefoundthatthe
jets are the most important feedback mechanism as compared to
theWAortheUFO.However,feedbackfromUFOsmaybesignif-
2 WARMABSORBERENERGETICS
icantincaseofhighEddington-ratio sources. Thefeedback from
jetsarehighlycollimatedandextendtodistancesupto Mpcandas InourearlierworkL1weconstrainedtheWAparameters(ξ,N
H
suchtheyarenotabletodistributethematerialoveralargesolid andv )for asampleof Seyfertgalaxies. Inthissectionwede-
out
WarmabsorbersinXraysII(WAX-II) 3
scribethemethodswehaveusedtocalculatethedynamicalparam- whereV isthevolumefillingfactorofthecloud(seeSection2.5
f
etersofWAfromthemeasuredWAparameters.Theseestimatesin- fordetails),L istheionisingluminosity,ξ istheionisationpa-
ion
volveseveralassumptions.Wediscusstheimplicationsandcaveats rameter,N isthecolumndensityandn isthehydrogendensity
H H
ofsuchassumptionsinthissection.Theerrorsonthederivedpa- ofthecloud.Thisdistanceestimatefollowsfromageometricalar-
rameters are calculated following the methods of statistical error gument,whichmaynotalwayshold.r calculatedusingEqua-
max
propagationfromtheerrorsonthemeasuredparameters. tion 3 yields estimates as large as a few Mpc (modulo V ). We
f
discusstheinterpretationoftheseresultsinSec.4.4.1.
WescaleallthedistanceswiththeSchwarzschildradiusofthe
2.1 WAradialdistance supermassiveblackhole(SMBH),
TheradialdistancesoftheWAcloudsfromthecentralengineare
2GM
bestestimatedusingthevariabilitystudiesofWAinresponsetothe r = . (4)
s c2
continuumchanges(seefore.g.,Reevesetal.2013;Krongoldetal.
2007; Kaspietal. 2004; Nicastroetal. 1999, and the references Whileweusethesubscript“min”and“max”forconsistencywith
therein).Suchastudyisbeyondthescopeofthispaper,andwillbe the literature published so far, we stress that the above estimates
doneinafuturework.Inthispaperwehavecalculatedtheradial arenotcommensurable.Inthispaperwewillthereforerefrainfrom
distancesusingthreedifferentconsiderations. calculating“meandistances”byaveragingr andr ,because
min max
Firstly,weconsiderthelaunchradiusr usingthevirialre- thestatisticalpropertiesofthedistributionofthisaverage(andthe
min
lationshipwhichassumesthattheobservedvelocityoftheWAis associated statistical uncertainties) are unknown. So r , r
min dust
theradialescapevelocityatthatdistancefromthecentralengine. and r will be treated separately. Wewill also treat separately
max
theestimatesofoutflowpropertiesdependentonthesedistances.
GM
r = . (1)
min v2
out 2.2 Massoutflowrate
AsacaveatwemustnotethatinafewcasesofX-raybinariesithas
The estimate of the mass outflow rate depends on the geome-
beenseenthattheouflowinggaseshavevelocitiesmuchlessthan
try of the outflow which involves the knowledge of volume fill-
theescapevelocityatthatradius(Milleretal.2006).
ing factor, covering fraction, density profile and outflow geome-
Secondly,thelaunchradiuscanalsobecalculatedbyassum-
try(conicalorsphericalorother)oftheWAcloudswhicharestill
ing that the WA originates at the base of the broad line region
largely unknown. We calculate the outflow parameters following
(BLR). A recent study by Czerny&Hryniewicz (2011) pointed
Krongoldetal.(2007)whoconsideredabiconicalgeometryforthe
outthatthebroadlineregion(BLR)inanAGNcouldoriginateas
WAoutflow.Themassoutflowrateinsuchascenarioisgivenby,
cloudsupliftedfromtheouterpartsoftheaccretiondiskwherethe
temperatureis∼ 1000K.Beyondthedustsublimationradiusthe
radiation pressure on the dusty clouds can sustain the radiatively M˙ =µπm N v r f(δ,φ), (5)
drivenoutflows,whilebelowthisradiusthedustgrainssublimate out(max/min) p H out (max/min)
andthereisnotenoughradiativepushonthecloudsandtheyfall wherem andN denotethemassofprotonandthecolumnden-
p H
back on thediskdue togravity. Netzer (2015) inarecent review sity of the WA clouds respectively. f(δ,φ) is a factor which de-
hasdiscussedhowthedustsublimationradiuscangiveusanesti- pendsontheanglebetweenthelineofsighttothecentralsource
mateoftheinnermarginsoftheBLR.Barvainis(1987)hadshown andtheaccretiondiscplane,δ,andtheangleformedbythewind
that for AGN dust heated by the central luminous source, a dust withtheaccretiondisc,φ.Wehaveassumedavaluef(δ,φ)∼1.5
sublimationradiuscanbedefinedas (Krongoldetal.2007;Tombesietal.2013).Theratiooftheproton
toelectronabundance(n /n )isexpressedasµandwehaveas-
H e
sumedaSolarvalueof 1/1.4. Wecompared thesemassoutflow
r =R ∼0.5∗L0.5(1800/T )2.6f(θ), (2)
dust Sub,graphite 46 sub estimates with a few other different methods in Appendix A and
foundthattheyaresimilartowithinanorderofmagnitude.
where L is the bolometric luminosity of the AGN in units of
46
1046ergs−1 andT isthedustsublimationtemperature(inK), Inourstudy,themassoutflowrateisscaledwiththeEdding-
sub
tonmassaccretionrate,whichisgivenby:
andf(θ)isanangulardependent termwhichis1foranisotropic
source.Hence,weassumef(θ)=1forsimplicity.Inawinddriven
byradiationpressureondustycloudsr isthereforeanorder-of- L
dust M˙ = Edd, (6)
magnitudeestimateofthelaunchradius.InFigure1,leftpanelwe Edd ηc2
showhowther compareswiththevirialestimatesofr in
dust min where L is the Eddington luminosity of the source, given by
oursample. Figure2showshowthetwodistanceestimatesr Edd
andr compareforeach25individualWA. min 1.3×1038(M/M⊙)ergs−1,andηistheaccretionefficiencyas-
dust sumedtobe0.1.
Afurtherestimateofthewarmabsorbingcloudlocationcan
be obtained using the geometrical definition of “cloud”. We as-
sume that its thickness ∆r, does not exceed its distance from
2.3 KineticLuminosity
theionisingsource(Krolik&Kriss2001;Blustinetal.2005).As
NH = nHVf∆r,imposing∆r = r yieldsanupper limitonthe The kinetic luminosity of the WA cloud isthe rate of the kinetic
cloudlaunchingradius energyemittedbytheWAcloudandisgivenbytheequation:
rmax= LξioNnHVf, (3) E˙K=LKE = 12M˙outvo2ut. (7)
4 Laha et al.
Figure1.LEFT:Thedistributionofrdust(inblue)andrmin(inred),bothscaledwiththeSchwarzschildradiusofSMBHrs.SeeSection2.1fordetails.
RIGHT:ThedistributionofrminoftheUFO(inblue)andWAX(inred),againscaledwithrespecttors.WefindthattheUFOandtheWAareseparatedata
distance103rs.
Figure2.Thedistributionoflog(rmin/rdust)forallthe25individualWAcomponentsoftheWAXsample.Wefindthatthedifferencedoesnotexceedan
orderofmagnitude.
Thisquantityisscaledby L inour study. Thebolometriclu- theytransfertheirmomentumtothecloud.Theamountofabsorp-
Edd
minosityL iscalculatedusingtheUV-XraySEDsgeneratedfor tiondependsontheopticaldepthofferedbythecloudstotheim-
bol
each source in our earlier study L1 in the energy range 1 eV to pingingphotons.Themomentumtranferredtothecloudduetothe
250 keV. absorptionofphotonsisgivenby
L
P˙ = abs,Tot. (10)
2.4 Momentumoutflowrate abs,Tot c
ThemomentumoutflowrateoftheWAcloudisgivenby: The total absorbed luminosity Labs,Tot for each source is calcu-
latedbyaddingtheL foralltheWAcomponentsdetectedina
abs
givensource. Similarly,fortheoutflowmomentumrateswehave
P˙out =M˙outvout, (8) consideredthetotalvaluesofthequantititesP˙out,TotandP˙abs,Tot
whilecorrelatingwiththesourceparameters.
andtheradiationmomentumrateisgivenby,
L 2.5 Volumefillingfactor
P˙ = ion, (9)
rad c
The volume filling factor, V , like the radial distance, is hard
f
where L is the ionising luminosity of the source measured in to estimate. Warm absorbers have been predominantly found
ion
therange1-1000Ryd.Theincidentionisingphotonsinteractwith to be clumpy in the form of discrete clouds in multi-phase
thewarm absorber clouds and get absorbed or scatteredwhereby ionisedmedium (see for e.g.,Bottorffetal. 2000; Krongoldetal.
WarmabsorbersinXraysII(WAX-II) 5
2005; Miniuttietal. 2014; Huertaetal. 2014; Coffeyetal. 2014; 3.2 Correlationandlinearregressionmethods
Lahaetal.2014).However,therehasnotbeenmuchconsensuson
For correlation analysis we have used the freely available
the clumping factor and hence the volume filling factor for WA
Pythoncode byNemmenetal. (2012) usingtheBCEStechnique
clouds, which varies from source to source. The previous stud-
(Akritas&Bershady1996)tocarryoutthelinearregressionanal-
ies on ionised absorptions in AGN indicate a large range in V ,
from 10−5 to 1 (Blustinetal. 2005; Kingetal. 2012). Followinfg ysisbetweenvariousWAdynamicalquantities.Inthismethodthe
errorsinbothvariablesdefiningadatapointaretakenintoaccount,
Blustinetal.(2005)wecalculatethevolumefillingfactorofeach
asisanyintrinsicscatterthatmaybepresentinthedata,inaddi-
of the warm absorbing clouds, assuming that the WA are purely
tiontothescatterproducedbytherandomvariables.Wealsotested
radiativelydriven.Insuchascenariothetotaloutflowmomentum
the strength of the correlation analysis using the non-parametric
rateofthecloudshouldequaltothemomentumduetoabsorption
Spearman rank correlation method. There are three WA compo-
andscatteringoftheionisingluminositybytheWA.Thisproposi-
nentswhoseoutflowvelocityisconsistentwithzero.Wehaveig-
tionmaynotalwaysbetrue,butthisgivesanorderofmagnitude
nored those components in our analysis as we are mainly inter-
estimateofV .ByequatingtheWAmomentumwiththeabsorbed
f estedinthedynamicpropertiesofWA.Wealsodonotincludean
andscatteredmomentumweobtain,
additionalfiveWAcomponents whosevelocitycouldnotbecon-
strained.Soourcorrelationanalysisincludes25WAcomponents.
M˙ v ∼P˙ +P˙ , (11)
out out abs scatt
wherethescatteredmomentumisgivenby,
4 RESULTSANDDISCUSSION
L
P˙scatt = cion(1−e−τT) (12) 4.1 Thedensityprofileofwarmabsorbers
TheopticaldepthforThomsonscatteringτ isgivenby The density profile of the WA clouds can be calculated using
T
the absorption measure distribution (AMD) method described by
Holczeretal. (2007) and Behar (2009). The absorption measure
τ =σ N (13)
T T H distributionisdefinedasAMD= dN /dlogξ,andmeasuresthe
H
Usingequations5and11,thevolumefillingfactorcanbewritten distributionofhydrogencolumndensityalongthelineofsightas
as, a function of the ionization parameter. It is calculated using the
differentionicstatesofthesameatom(fore.g.,Fe)detectedina
givensourceacrosstheX-rayspectrawithdifferentionizationpa-
(L +L (1−e−τT))ξ
V ∼ abs ion . (14) rameter and ionic column densities. We can estimate the AMD
f 1.23m cL f(δ,φ)v2
p ion fromtheWAXsamplebyassumingthatthedifferentWAarethe
WelistthevolumefillingfactorsofeachWAcomponentinTable9. manifestationofthedifferentstagesofthesameabsorber(seealso
Tombesietal.2013).Takingthederivativeofthelinearregression
relation,logN = alogξ+b,whereaandbarethebestfitlin-
H
2.6 TheUFOdata ear regression slope and intercepts respectively (seeFigure 5 left
panel,andTable10ofL1),wemaywritetheAMD∝ ξa,where
Fortheultrafastoutflows(UFOs)wehaveusedthekinematicdata
from Tombesietal. (2012) and Tombesietal. (2013). From their a = 0.31 ± 0.06 and b = 20.46 ±0.11. The slope of the ra-
dial density profile (n ∝ r−α) from Behar (2009) is given by
study, we have considered the minimum and maximum distance
α=(1+2a)/(1+a)±∆a/(1+a)2.Bysubstitutingthevalue
estimatesoftheUFOandtheircorrespondingoutflowparameters
separatelyasdescribedinSection2.1. ofainthisequationweobtainα=1.236±0.034,whichissim-
ilartothatobtainedbyBehar(2009)fromasmallbutwellstudied
sampleoffiveSeyfertgalaxies(1<α<1.3).Thisconclusionval-
idatesouroriginalassumptionthattheglobalWApropertiesinthe
3 CORRELATIONANALYSIS
WAXsample could be considered representative of each individ-
3.1 Choiceofcorrelations ualsourceoutflowevolvingthroughdifferentphasesofionicstates
andcolumndensities.Giustini&Proga(2012)hadsuggestedthat
TherearethreeWAparameterswhichareindependentlymeasured
theinformationwederivefromtheabsorptionlinesforindividual
(ξ,N ,v )andfoursourceparameterswhichareindependently
H out WAareinsufficienttocommentonthegrosspropertiesofthewind.
derived(L ,L ,L ,andM )inourprevious studyL1.
ion bol Xray BH Fromourearlierpropositionthereforethiseffectcanbemitigated
Thecorrelationandlinearregressionanalysisinvolvingthesource
toanextent,ifwestudytheWApropertiesinasample,asinWAX.
parametersarereportedinTable1.CorrelationsinvolvingtheWA
Wewilldiscusstheimplicationsoftheestimateddensityprofilein
arecarriedoutinthreesets,reportedinTables2,3and4,wherethe
Sect.4.3.
outflowparametersareestimatedusingthevirialdistancer ,the
min
dust sublimation distance r and themaximum distance r ,
dust max
respectively. We list the source luminosities in Table 5. The Ta-
4.2 Originofwarmabsorber
bles 6-9 list the calculated distances and the outflow parameters
inthesethreedifferentscenariosalongwiththeirstatisticalerrors. InthisSectionweaimatconstrainingthelocationwherethewind
ThewarmabsorbedluminositiesarelistedinTable6.Whereverthe couldbelaunched.Thelaunchingscalemayprovidecluesonthe
correlation involves the source parameters (for e.g., P˙ , L , outflow launching and acceleration mechanism. The virial esti-
rad Xray
L )wehaveaddedthecorrespondingWAkinematicalquantities matesoftheWAdistances,r ,intheWAXsamplerangefrom
bol min
foragivensourceiftherearemultipleWA.Weusethesuffix‘Tot’ 1016−1018 cm(∼0.01−1pc).Wecalculateanapproximatedis-
wheneverthatisdone. tanceofthetorusfollowingKrolik&Kriss(2001),whichisgiven
6 Laha et al.
byr ∼ L0.5 pc,calculated considering the dust sublima- thorsalsopredictedthatthereshouldbeanabruptdropintheioni-
torus ion,44
tiontemperatureandtheeffectsofphoto-ionisation.Welisttheval- sationparameteratthepointoftransitionbetweentheUFOandthe
uesofr inTable6.Wefindthatthetorusdistanceisonanaver- WA.FromFig.4rightpanel,wefindthatataradiusof∼ 103r ,
torus s
ageanorderofmagnitudehigher(∼1−10pc)thantheestimated thereisadropintheionisationprameterbetweentheUFOandthe
r fortheWA.Thismayput theWAintheinner torusregion. WA.Foranadiabaticallyshockedwind,thedropinthevelocityand
min
Inthelastoneandhalfdecadeofhighresolutionspectralstudyof theionisation parameter should beof similar magnitude. Hence,
AGN,several authorshave calculatedthelaunching radiusof the foreverysourcewherebothWAandUFOhavebeendetected,we
WAatadistancerangespanningsixordersofmagnitude,fromac- have compared the highest ionisation parameter of WA with the
cretiondiskwindsat∼0.001−0.01pc(Elvis2000),toobscuring highestionisationparameterofUFOandtheircorrespondingout-
torusat ∼ 0.1−1pc(Krolik&Kriss2001; Blustinetal.2005), flowvelocities.FromTombesietal.(2011)andL1,wefindthatthe
tothenarowlineregion100−1000pc(Kinkhabwalaetal.2002; ratioofthemaximumUFOvelocitywiththehighestWAvelocity
Ogleetal.2004).Tilldatetherehasnotbeenaconsensusaboutthe forthesourcesthatexhibitbothUFOandWAis∼10−30while
originoftheWA.However, thedistancesestimatedfromtheWA thedrop intheionisationparameter islarger∼ 10−103.These
response tothecontinuum changes insomesources haveyielded resultspointtothefactthattheWAcouldpossiblybeproducedby
verywellconstrainedupper limits.Table10showsacompilation shockbytheUFOontheISMorthetorus.
oftheWAdistancesforafewbrightwellstudiedsources,Mrk509,
NGC4051,MR2251-178,NGC3516,andNGC3783.Theseesti-
matesputtheWAcloudsatadistancerangeof∼0.001−100pc 4.3 Warmabsorbermechanismofacceleration
andsometimeswthalowerlimitofr >71pc.FromTables6and InourpreviousstudyL1,wehadfoundthattheslopeoflogξ vs
10wefindthattheminimumdistanceestimatesofWArminmostly logvout intheWAXsampleis0.12±0.03whichisinconsistent
agreewiththewellconstraineddistanceestimatestowithinanor- witheitherpurelyradiativelydrivenormagneto-hydrodynamically
derofmagnitude,exceptforthesourceNGC4051,wherermin is driven(MHD) wind. Inthissectionweinvestigatethepossibility
fourordersofmagnitudelargerthantheconstrainedestimates. ofdifferentdrivingmechanismsonthebasisofthecorrelationswe
Krolik&Kriss(2001)havearguedthattheWAcouldpossi- obtainbetweenthedifferentoutflowparametersofWA.
blybethecloudsformedfromevaporationoftheinneredgeofthe Panelsa,b,c,d,e,f,g,andhofFigure3showthecorrelation
obscuringtorusduetothehighlyintensecentralradiation.Recent between thesource parameters (logP˙ , logL ) withthe out-
rad bol
studies by Czerny&Hryniewicz (2011) suggested that the BLR flowmomentumrateofWA,logP˙ andlogP˙ ,aswell
out,min out,dust
clouds arisebeyond the dust sublimation radius, wherethethrust astheWAkineticluminosity,logE˙ andlogE˙ .
K,min,Tot K,dust,Tot
onthedustgrainscoulddrivetheoutflow.Thus,thedustsublima- The correlation and linear regression parameters are reported in
tionradiuscouldrepresent alowerlimittotheoutflow launching Tables 2 and 3. These correlations are particularly chosen to in-
radius.Inourstudywefindthatthedustsublimationradiusforthe vestigatetheeffectofsourceradiationontheWAoutflowparam-
WAXsourcesrangefrom∼0.1−1pc(seeTable6).FromFigure eters.Inanidealsituationofapurelyradiativelydrivenwind,we
1leftpanel,weseethatthedistributionoftheminimumlaunchra- wouldexpecttoseeastrongpositivecorrelationbetweenthesource
diuslogrmin estimatedusingthevirialrelationoverlapswiththe luminosity and the WA momentum rates and kinetic luminosity.
dustsublimationradiuslogrdust ofthesourcesintheWAXsam- However, we find that the correlations in most cases show sig-
ple. Figure 2 shows that the virial distance estimates of the indi- nificantamountofscatter,implyingthataccelerationmethodsare
vidualWAcomponentsagreewiththedustsublimationradiusfor more complex. Possibly the acceleration of the WA is caused by
everysourcetowithinanorderofmagnitude. Theseresultspoint a complex combination of several mechanisms. Despite the scat-
to the fact that the warm absorbers possibly originate in the in- ter, in almost all the cases we find a positive linear trend of in-
nertorusregionintheformofheatedtoruswindsasproposedby creaseofWAoutflowmomentumrateandkineticluminositywith
Krolik&Kriss (2001), with a significant amount of dust opacity thesourceluminosity. Frompanelsa,b,candd,wefindthatthe
which can drive the outflow. There has been an extensive debate outflowmomentumratelogP˙ andlogP˙ oftheWA
out,min out,dust
in the last couple of decades as to whether the WA are dusty or cloudsincreaseswithboththeradiationmomentum ratelogP˙
rad
not(seefore.g.,Leeetal.2001;Sakoetal.2003;Vasudevanetal. and bolometric luminosity logL of the source. This points to
bol
2013;Ishibashi&Fabian2015;Thompsonetal.2015,andtheref- thefactthatastrongersourcefluxdrivesacloudwithhighermo-
erences therein).Fabianetal.(2008) hadsuggested thatthepres- mentumrate.Frompanelseandfwefindthatthetotalabsorbed
enceofdustenhancestheradiationpressureforThomsonscattering momentumrateoftheWAlogP˙ increaseswiththeoutflowmo-
abs
andthusdrivesmassoutflowsevenforsub-Eddington luminosity mentumratelogP˙ andlogP˙ pointingtothefactthat
out,min out,dust
sources. For the WA with low ionisation (logξ < 1) we would thecloudswithgreaterabsorbedmomentum ratehavegreaterto-
expectthatdustplaysanimportantroleindrivingtheoutflows. taloutflowmomentumrate.Frompanelsgandhwefindthatthe
A recent study by Pounds&King (2013) showed that the kinetic energy of the outflows increase with the increasing bolo-
WA could arise out of a Compton cooled shocked wind, when a metricluminosity of the source. All of these correlations suggest
fast,highlyionisedwind,launchedveryneartotheSMBH,loses that although the overall WA driving mechanism is complex, the
mostofitsmechanicalenergyaftershockingagainsttheinterstellar incidentradiationfromthesourceplaysacrucialroleinaccelerat-
medium(ISM). ForthesourceNGC4051,withablackholemass ingtheWAoutflows.Inotherwords,theWAcloudshaveastrong
oflog(MBH/M⊙) ∼ 6,theauthorshavecalculatedtheshockra- radiativelydrivencomponent.
dius to be ∼ 1017 cm. From Fig. 1 right panel, we find that the The radiative pressure by the photons are imparted on the
launchingradiusoftheUFOandtheWAareseparatedataradius cloudsbyabsorptionandscattering.TheUVandsoftX-raypho-
∼103r .FromTable6wefindthattheSchwarzschildradiusr for tonsplaythemost important roleinimpartingmomentumdueto
s s
the WAX sample of sources ranges between 1012−14 cm, which absorption,whilethehardX-rayphotonsimpartmomentumtothe
impliesthatthebreakintheradiuscomesataround1015−17 cm. cloud via Thomson scattering. The latter is a much weaker pro-
Thisissimilartothose foundbyPounds&King(2013).Theau- cessincomparisontolinedrivenforce(Everett&Ballantyne2004;
WarmabsorbersinXraysII(WAX-II) 7
Gallagheretal. 2015). However, the question arises, how a BLR tonratio(λ=L /L )source.Thisisthetypicalscenariofor
bol Edd
cloudlocatedveryneartothecentralsourcewithstrongX-rayir- the ultra-fast-outflows as discussed by Tombesietal. (2013) and
radiationstillhasenoughboundelectronstoberadiativelydriven? Goffordetal.(2015b).
Thisscenario hasbeen extensivelystudied byProga&Begelman Fabianetal.(2008);Ho¨nig&Beckert(2007)haveshownhow
(2003); Proga&Kallman(2004). They suggest that if an already the presence of dust enhances the radiative thrust on the winds
launchedcloudmovesupintheatmosphereoftheAGN,itsden- duetotheionising continuum. Evenfor sub-Eddington luminous
sity falls and its temperature increases, and it gradually becomes sources,thecloudscangetathrustequivalenttosourcesemitting
fullyionised,andatthatstageifitfailstoattaintheescapeveloc- at an Eddington rate. InSect. 4.2 wefindthat theWA can likely
ity,itfallsbacktotheAGNdisk.These“failedwind”cloudscould originatefromthedustsublimationradiusintheouterpartsofthe
havegainedenoughopacitytoshieldtheothercloudsfromtheX- accretiondisk or thedustytorus. Thispointstothepossibilityof
rayionisingphotons,therebyhelpingthemtoflowout.Alimitation presence of dust in the WA for the clouds with lower ionisation
inthis‘failedwind’scenario,isthat,iftheinfallingwindsscreen parameter∼ logξ < 1. Inadustdrivenscenarioonewouldex-
the other parts of the wind from X-rays, we would expect to see pecttogetanegativeslopeoflogξ vslogv correlation,asthe
out
redshiftedX-rayabsorptionlinesfromthesewinds.Butexceptfor lowerionisation stateswillbedrivenfaster. Ontheother hand in
twocasesintheWAXsample,wherethewarmabsorbervelocities apurelyradiativelydrivenwindscenariowewouldexpect apos-
areconsistentwithzero,allotherWAareoutflowingwithrespect itive slope with higher ionisation states outflowing faster. In L1,
tothesystemicvelocity.Wefindnotraceofthesescreening‘failed wefindthattheslopeoflogξvslogv correlationisnearlyflat
out
winds’. ∼0.12±0.03,whichmaypointtowardsacombinationoftheef-
ImprovedsimulationsofradiativelydrivenwindsinAGNby fects of dust driven wind for the lower ionisation states and line
Simetal. (2010) showed similar results that these winds could drivenwindforthehigherionisationstates.
produce the higher energy absorption features (2 − 10 keV) of
the spectrum of the quasar PG1211+143, but fail to produce the
lower ionisation features Ne IX or O VII in the soft X-rays. This
is due to the fact that the huge X-ray flux from a high Edding-
4.3.1 Alternativescenarios
ton ratio source has fully ionised the cloud. A recent theoretical
study by Higginbottometal. (2014) found that the purely radia-
Early studies on magneto-hydrodynamical (MHD) winds by
tively driven winds are more ionised than that was predicted by
Blandford&Payne (1982) demonstrated that energy and angu-
Proga&Kallman (2004), and as such these winds will have no lar momentum can be effectively removed magnetically in the
UVorsoftX-rayspectrallines.So,ineffect,thepurelyradiatively
form of outflows from accretion disks, leading to visible sig-
drivenwindsscenarioisefficientonlyifthereisX-rayshielding.
natures of collimated jets and uncollimated winds. More re-
If indeed there is some form of X-ray shielding, we should cent studies by Kazanasetal. (2012); Fukumuraetal. (2010a,b);
be able to detect that in the X-ray absorption spectrum. We find Everett&Ballantyne(2004)presentedtwodimensionalmagneto-
aninterestingcorrelationinFigure5,rightpanel.Theratioofthe hydrodynamic winds, originating from the accretion disk winds
total absorbed X-ray luminosity by the WA clouds Labs to that irradiated by a central X-ray quasi stellar object (QSO).
of the incident X-ray luminosity (0.3−10 keV) is a constant at Fukumuraetal. (2010a,b) found that for the chosen density pro-
Labs/LXray ∼5%acrosstheLXrayvalues.Theslopeofthelinear filen(r) ∝ r−1,thepredictedoutflow absorption featuresarein
regressionbetweenlogLXrayandlogLabsis∼1. Theratioofthe goodagreementwiththeX-rayspectrafromseveralAGN.Inour
quantityLabs,Tot/LXray = 1040.25/1041.5 = 0.056 atthepoint study we find that the slope of the density profile for the WA is
wherethebestfitlinearregressionlineintersectstheY-axisinthe α = 1.236±0.034, consistent withtheassumption inthestudy
figure,impliesa∼ 5%absorption.PerhapstheWAarescreening byFukumuraetal.(2010a)whoseconclusionscouldbeappliedto
the outflowing clouds with lower ionisation stateslocated further theWAXsampleaswell.However, theauthorsalsomentionthat
out from the central source radiation. The scatter in the correla- foraMHDwind,theUVspectraneedstobeverystrong,withan
tionmaybetheresultofthedifferentviewinganglesfordifferent α >2,whichisnotthecasefortheWAXsources,whereα is
OX OX
sources. ˚
given by the expression 0.385log fν(2500A) (Tananbaumetal.
TheotherpossibleradiativeaccelerationmechanismisThom- (cid:20)fν(2keV)(cid:21)
son scattering, which is particularly relevant for highly ionised 1979).AnobservableofanMHDdrivenwindisthattheoutflow
cloudswhoseatomshavebeenstrippedofftheirboundelectrons. velocityisproportionaltotheionisationparameteroftheoutflow-
Poundsetal.(2003);King(2010)haveextensivelystudiedthecase ingcloud.InL1wehadstudiedthecorrelationbetweenv and
out
of an electron scattered wind and conjectured that in such a sce- ξfortheWAXsampleofwarmabsorbersandfoundthatthelinear
nario one would expect the momentum outflow rate P˙ of the regression slope 0.12±0.03 isinconsistent withthescaling law
out
cloudtobeproportionaltotheincidentradiationfieldP˙rad,i.e.,a predictedforMHDwinds(vout ∝ξ).InFigure6weshowthelin-
correlationbetweenlogP˙ andlogP˙ wouldyieldalinearre- earregressionresultsforindividualsources,andwefindthatthey
out rad
gressionslopeof1.FromFig.3,panelsaandb,wefindthatthe haveawiderangeofvaluesfordifferentsources,from0.00±0.05
slopesofthelinearregressionare1.06±0.10and1.20±0.19for inNGC3783to0.89±0.06inMRK704.Thisindicatesthatthe
logP˙ vslogP˙ andlogP˙ vslogP˙ respectively. drivingmechansimsofWAisvariedandnotonesingleeffectcan
out,min rad out,dust rad
ThisissimilartothatexpectedforaThomsonscatteredcloud.For explainallthecases.
aThomsonscatteredwind,P˙ andP˙ ispredictedtobeofsim- Inviewofthediscussioninthissectionwesuggestthattheac-
out rad
ilar magnitude. However, for the WA we find that P˙ is an or- celerationmechanismforwarmabsorbersiscomplex.Notasingle
out
der of magnitude lower than P˙ . We conclude that in the WA physicalprocesscancapturetheentirephysics.However,radiative
rad
clouds,Thomsonscatteringmaynotcontributetowardsaccelerat- accelerationbyUVandsoftX-raylineabsorptionisapredominant
ingthecloud.Itistobenotedthatthisprocessispredominantfor mechanism.ThecontributionsfromMHD-drivenmechanismscan-
highlyionised,highcolumndensitycloudsfacingahighEdding- notberuledout.
8 Laha et al.
34.0 34.0
RS=0.47,Pnull=0.09
33.5 RS=0.34,Pnull=0.23 33.5 y=1.20−+00..1199x−8.90−+66..5555
33.0 y=1.06−+00..1100x−4.07−+33..5533 33.0
)Tot32.5 )Tot32.5
min,32.0 dust,32.0
˙og(Pout,3311..05 ˙og(Pout,3311..05
l l
30.5 30.5
(a) (b)
30.0 30.0
29.5 29.5
32.0 32.5 33.0 33.5 34.0 34.5 35.0 35.5 32.0 32.5 33.0 33.5 34.0 34.5 35.0 35.5
log(P˙ ) log(P˙ )
Rad Rad
34.0 34.0
RS=0.45,Pnull=0.10 RS=0.59,Pnull=0.02
33.5 y=1.11−+00..1177x−17.59−+77..5588 33.5 y=1.28−+00..2233x−24.92−+1100..5544
33.0
33.0
)Tot32.5 )Tot32.5
˙og(Pout,min,333121...005 ˙og(Pout,dust,3321..05
l l
31.0
30.5
30.0 (c) 30.5 (d)
29.5 30.0
43.0 43.5 44.0 44.5 45.0 45.5 46.0 43.0 43.5 44.0 44.5 45.0 45.5 46.0
log(L ) log(L )
Bolometric Bolometric
33.5 33.5
RS=0.56,Pnull=0.03 RS=0.37,Pnull=0.19
33.0 y=0.77−+00..1177x−6.93−+55..4433 33.0 y=0.81−+00..1155x−5.68−+44..9966
32.5 32.5
32.0 32.0
˙P)abs31.5 ˙P)abs31.5
g( g(
o o
l l
31.0 31.0
(f)
30.5 30.5
(e)
30.0 30.0
29.5 29.5
29 30 31 32 33 34 29.5 30.0 30.5 31.0 31.5 32.0 32.5 33.0 33.5 34.0
log(P˙ ) log(P˙ )
out,min,Tot out,dust,Tot
43 43
RS=0.52,Pnull=0.058 RS=0.60,Pnull=0.02
42 y=1.36−+00..2200x−21.10−+99..0077 42 y=1.58−+00..3300x−30.85−+1133..5599
)Tot41 )Tot41
min,40 dust,40
K, K,
˙E 39 ˙E 39
g( g(
lo 38 lo 38 (h)
(g)
37 37
36 36
43.0 43.5 44.0 44.5 45.0 45.5 46.0 43.0 43.5 44.0 44.5 45.0 45.5 46.0
log(L ) log(L )
Bolometric Bolometric
Figure3.Thecorrelation between theWAoutflow momentumrate derived usingthevirial distance scale P˙out,min,Tot andthe dustsublimation radius
P˙out,dust,Tot,withthesourceparameters.SeeSection4.3fordetailsandTables2and3forthecorrelationparameters.
WarmabsorbersinXraysII(WAX-II) 9
10
24 Rs=−0.40, Pnull∼0.049 Rs=−0.46, Pnull∼0.019
y=−0.97−+00..1144 x+25.38−+00..7744 8 y=−2.22−+00..4411 x+11.50−+11..7711
23
6
)
NH22 gξ 4
( o
g l
o
l
2
21
0
20
−2
0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7
log(r /r) log(r /r)
min s min s
Figure4.Theevolutionofthewarmabsorberobservablesasafunctionofthelaunchingradiuscalculatedassumingvirialrelationship.Thebluedatapoints
aretheUFOfromTombesietal.(2013).TheupperandlowerlimitsoftheUFOdatapointsareshowninbluearrow-heads.Thecorrelationsareexplainedin
Section3.2
42.5 43.5
RS=0.61,Pnull=0.01 R =0.60,P =0.023
S null
42.0 y=0.86−+00..1177 x−20.52−+44..1177 43.0 y=0.93+00..1111 x +1.18+00..4433
− −
)
Å41.5 42.5
7
1 )
− ot
(15 41.0 bs,T42.0
TA La
U40.5 ( 41.5
Labs, log
g 40.0 41.0
o
l
39.5 40.5
39.0 40.0
21.5 22.0 22.5 23.0 23.5 24.0 24.5 25.0 41.5 42.0 42.5 43.0 43.5 44.0 44.5 45.0
log(M˙out,min,Tot) logLXray(0.3−10keV)
Figure5.LEFT:Thecorrelation between theoutflow massoutflow ratevs absorbedluminosity bytheUTA.RIGHT:Thecorrelation between theX-ray
luminosityandthetotalwarmabsorbedluminosityforeachsource.
4.4 TheWAfeedbacktogalaxies tion3. Crenshaw&Kraemer(2012)havealsocalculatedr of
max
theorderof1023−1026 cm∼100kpc−100MpcforWAinsev-
4.4.1 Caveatsonrmaxestimates. eralsources,usingequation3.ThesevaluesimplythattheWAcan
befoundmuchbeyondthehostgalaxiesandmaybesometimesin
Inthissectionwediscussthecaveatsandshortcomingsofthees-
theintergalacticmedium(IGM).MostoftherobustWAdistance
timatesofr .Firstly,r arisesfromageometricalconstraint
max max estimates from variability studies put them between 0.001pc to
∆r = r,where∆r isthethicknessofthecloudandristhedis-
fewtensof pc(seeTable10),whichinturnquestionsthevalidity
tanceoftheinnersurfaceoftheWAcloudfacingtheionizingra-
ofequation3.
diation,wheretheionisationparameterξ forthecloudisdefined.
Keeping in mind these caveats, we estimate the outflow pa-
Theequalityimpliesthatinnersurfacedistanceofthecloudfrom
rameterscorrespondingtor anddiscusstheresultsinthesec-
theionisingsourceandthecloudthicknessareequal.Theinnersur- max
tionsbelow.
facedistanceandthethicknessofthecloudareentirelyunrelated
quantities.Insteadtheoutersurfacedistanceofthecloud(R)could
putalimitonthethicknessofthecloud(∆r 6 R).Butunfortu-
4.4.2 WAfeedback
nately,wedonothaveameasureoftheouterextentofthecloud.
However, keeping inmindtheoutflowliteraturepublished sofar, A measure of the WA feedback to host galaxies can be obtained
wehavecalculatedrmaxusingequation3foreveryWAcomponent bystudyingtheWAmassoutflowrateM˙out incomparisontothe
foracomparison. SMBHmassaccretionrateM˙ andthekineticluminosityofthe
acc
Secondly, from Table 6 we find that at least one of the WA outflow E˙ incomparison tothe bolometric luminosity L
K,out bol
has r ∼ 1Mpc and five others have r ∼ 100kpc. of the source. Some of the most interesting questions regarding
max max
Tombesietal.(2013)inacompilationofthewarmabsorberstudies the AGN-galaxy co-evolution can be answered by observational
foundsimilarr rangingupto1025 cm∼10Mpc,usingequa- studies of outflow impact on the host galaxies. For e.g., chemi-
max
10 Laha et al.
Figure6.Theindividualplotsforlogξvslogvoutforthesourceswith2ormorecomponentsofWAintheWAXsample.Thetitleofeachplotreportsthe
resultsofthebest-fitwithafunctionvout=A×ξa.Theyellowboxesrepresenttheenvelopeofthebest-fitfunctionscorrespondingtoa1−σerroronthe
bestfitparameters.
cal enrichment of the host galaxy, the relation between the mass isrequiredforthemassoutflowratesoftheWAnottogreatlyex-
ofSMBHandthestellarvelocitydispersion(M −σrelation),the ceed theaccretion rate. Thelargemass outflow rateas compared
formationoflargescalestructuresintheearlyuniverseandthere- tothemassaccretionrateindicatesthatmostofthematterwhich
lationbetweenSMBHandgalacticbulgegrowth.DiMatteoetal. is approaching the black hole is being expelled and only a small
(2005);Hopkins&Elvis(2010)havedemonstratedthatanoutflow fractionisreachingtheblackhole.
withE˙ /L aslow as∼ 0.5% cangivesufficientfeedback to FromFigure8rightpanelwefindthatthemoremassiveout-
K bol
thehostgalaxytostopthecoolingflowsinthehostgalaxywhich flowsaretheoneswhichhavelowercolumndensities(N )oral-
H
supplytherawmaterialtotheaccretiondisk.Seyfertsareprimarily ternatively lower ionisation parameter ξ, for unit volume filling
hostedinspiralgalaxies,forwhichthispercentageismuchlower, factor.PreviousstudiessuggestedthatFeMshellunresolvedtran-
aslowas0.1%(Gasparietal.2011,2012)toaffectthehostgalaxy, sition array (UTA) absorption could carry away the largest mass
asagainstthemorecompactellipticalgalaxies. outflows (Holczeretal. 2005; McKernanetal. 2007). We calcu-
lated the absorbed luminosity for each warm absorbed source in
From Figure 7 and Table 9 we find that the WA maximum
thewavelengthrange15−17A˚ whichweassumetobetherepre-
kineticenergycanexceedthebolometricluminosityoftheAGN,
sentativeoftheUTAabsorption.Fig.5leftpanel,showthatthereis
sometimesevenbyanorderofmagnitude, forunitvolumefilling
acorrelationbetweentheUTAabsorbedluminositywiththetotal
factor V and assumingr estimateinequation 3.However, if
f max
wemultiplyE˙ ofeachoftheWAcomponentbytherespec- massoutflow rate. Thelinear trendsuggests that higher UTA ab-
K,max
sorptionleadstohighermassoutflowrates.Thisindicatesthatthe
tiveV (seeTable9),weobtainthebluepointsinFig.7.Wefind
f
UTAabsorbersmaybethedominantmassoutflowcomponent.
thataftertakingintoaccountthevolumefillingfactor,thekinetic
luminosityoftheWAare< 0.5%L .Thereishowever,alarge
bol
uncertaintyintheestimateofthefillingfactor.
From Figure 8, left panel, we find that the distribution of
4.5 TheWAandtheUFO:Aretheysimilaroutflows?
the maximum mass outflow rates of the warm asorbers (red his-
tograms), scaled with respect to the Eddington mass accretion Therehasbeenlongstandingquestionastowhetherthewarmab-
rate, exceed the latter by several orders of magnitude (∼ 105), sorbersandtheUFOsarethesametypeofoutflows.Ouranalysisin
forunitvolumefillingfactor.PreviousstudiesbyMcKernanetal. L1hadshownthattheWAandtheUFOdonotlieonthesamecor-
(2007) and Crenshaw&Kraemer (2012) have also found that relationslopeintheparameterspacesofξ,N andv ,andhence
H out
M˙ /M˙ is of the factor 10 − 1000 for unit volume fill- mostprobablynotthesametypeofoutflow.Inprinciple,WAand
out Edd
ing factor. In a study on the WA of the source MR 2251-178, UFOsdenotetwoverydifferenttypesofcloudwithdistinctlydif-
Goffordetal.(2011)havefoundthataclumpingfactorof∼10−3 ferentξ,N andv distributions.Belowwediscusstherelation
H out