Kiloparsec-scale jets in three radio-loud narrow-line Seyfert 1 galaxies

0.75 MB·English

by  Joseph L. Richards

DraftversionJanuary23,2015
PreprinttypesetusingLATEXstyleemulateapjv.5/2/11
KILOPARSEC-SCALEJETSINTHREERADIO-LOUDNARROW-LINESEYFERT1GALAXIES
JosephL.Richards∗andMatthewL.Lister
DepartmentofPhysicsandAstronomy,PurdueUniversity,525NorthwesternAve,WestLafayette,IN47907,USA
DraftversionJanuary23,2015
ABSTRACT
Wehavediscoveredkiloparsec-scaleextendedradioemissioninthreenarrow-lineSeyfert1galaxies(NLS1s)
5 in sub-arcsecond resolution 9 GHz images from the Karl G. Jansky Very Large Array (VLA). We find all
1 sources show two-sided, mildly core-dominated jet structures with diffuse lobes dominated by termination
0 hotspots. These span 20–70 kpc with morphologies reminiscent of FR II radio galaxies, while the extended
2 radioluminositiesareintermediatebetweenFRIandFRIIsources. Intwocasesthestructureislinear,while
a 45◦ bend is apparent in the third. Very Long Baseline Array images at 7.6 GHz reveal parsec-scale jet
n
structures, in two cases with extended structure aligned with the inner regions of the kiloparsec-scale jets.
a
J Based on this alignment, the ratio of the radio core luminosity to the optical luminosity, the jet/counter-jet
intensityandextensionlengthratios,andmoderatecorebrightnesstemperatures((cid:46)1010K),weconcludethese
1
jets are mildly relativistic (β(cid:46)0.3, δ∼1−1.5) and aligned at moderately small angles to the line of sight
2
(10–15◦). The derived kinematic ages of ∼106–107 y are much younger than radio galaxies but comparable

] tootherNLS1s. Ourresultsincreasethenumberofradio-loudNLS1swithknownkiloparsec-scaleextensions
A from seven to ten and suggest that such extended emission may be common, at least among the brightest of
G thesesources.
Subjectheadings:galaxies: active—galaxies: jets—galaxies: Seyfert—galaxies: individual(J0953+2836,
.
h J1435+3131,J1722+5654)—radiocontinuum: galaxies
p
-
o 1. INTRODUCTION areknownouttoz=0.8sothiscorrespondsto(cid:38)10kpc,leav-
r
ingarangeofkiloparsecscaleslargelyunexplored. Recently,
t Narrow-line Seyfert 1 galaxies (NLS1s) are a peculiar
s Doietal.(2014)reportedextendedemissioninaradio-quiet
a class of active galactic nuclei (AGN). They resemble ordi-
NLS1.
[ nary Seyfert 1 galaxies but their optical broad lines are nar-
1 rower (FWHM(Hβ)≤2000kms−1). The black hole masses scaInlertahdisiowemorikss,iowneinpthrerseeenrtadtihoe-loduedteNctLioSn1so(fJ0k9i5lo3p+a2r8s3ec6-,
v ofNLS1sarerelativelysmall(105−108 M(cid:12);e.g.,Zhouetal. J1435+3131, and J1722+5654). These are the first such de-
2006) and their accretion rates are high, often a substantial
9 tections in these sources, all of which were detected but un-
9 fractionoftheEddingtonrate(Bolleretal.1996).Ithas,how- resolved by the FIRST survey (White et al. 1997). This in-
2 ever,beensuggestedthatthisisaresultofsystematicunder- creases the number of radio-loud NLS1s known to be ex-
5 estimationoftheblackholemasses(Decarlietal.2008;Mar- tendedonkiloparsecscalesfromseventoten.Wealsopresent
0 conietal.2008;Calderoneetal.2013). About7%ofknown
parsec-scale radio images showing bright jet-like structures.
1. NLS1s are radio-loud (Komossa et al. 2006) and it is clear Wherenecessary,wehaveassumedaflatΛ-ColdDarkMatter
that jets are present in some of these (e.g., Zhou et al. 2003;
0 Yuanetal.2008). Thedetectionofgamma-rayemissionfrom cosmologywithΩΛ=0.7and H0=70kms−1Mpc−1. Spec-
5 tral indices are specified with flux density S ∝ να at fre-
severalradio-loudNLS1sprovidesevidencethatthesejetsare ν
1 quency ν. Velocities are quoted as fractions of the speed of
relativistic(e.g.,Abdoetal.2009). Thiswasunexpectedbe-
: light,β=v/c.
v cause jets in AGN are typically associated with large black
i holes,whilehighaccretionratesinstellar-massblackholebi- 2. OBSERVATIONSANDDATAREDUCTION
X
nariesnormallycorrespondtoquenched-jetstates(e.g.,Boro- Weobservedthreeradio-loudNLS1swiththeKarlG.Jan-
r
a son2002;Maccaroneetal.2003). StudyofthejetsinNLS1s skyVeryLargeArray(VLA)andtheVeryLongBaselineAr-
willthereforehelpusunderstandhowtheprocessesunderly- ray(VLBA).TheVLAobservationsweremadetoobtainra-
ing jet production scale with black hole mass (e.g., Heinz & dio coordinates accurate enough for correlation as part of a
Sunyaev2003;Foschini2012). VLBA program monitoring the 15 known radio-loud NLS1s
Radioemissiononkiloparsecscaleshasbeenfoundinonly above0◦declinationwitharchivalcentimeter-bandfluxdensi-
a few NLS1s. Together, Whalen et al. (2006), Anto´n et al. tiesexceeding30mJy.(Richardsetal.,inprep.). Amongthe
(2008),Gliozzietal.(2010),andDoietal.(2012)reportedsix 15, only these three lacked sufficiently precise coordinates.
examplesfromthe1.4GHzFaintImagesoftheRadioSkyat Propertiesofourtargetsandourrefinedcoordinatesarelisted
Twentycentimeters(FIRST)survey(Beckeretal.1995)and inTable1.
4.8 GHz Australian Telescope Compact Array (ATCA) ob- TheVLAobservationsweremadeon15Feb2014andcon-
servations. Theresolutionoftheseobservationswaslimited, sisted of a single 10 minute snapshot of each source sand-
however. The 5(cid:48)(cid:48) FIRST beam only resolves sources (cid:38)2(cid:48)(cid:48), wichedbetweenshortobservationsofanearbyphasecalibra-
whiletheATCAbeamwasaboutafactoroftwobetter.NLS1s torwithaknownposition(betterthan2mas).Ashortscanon
3C286wasusedtocalibratethefluxdensityscale,applying
∗[email protected] theappropriatemodeltoaccountforresolvedstructure.Atthe
2 J.L.Richards&M.L.Lister
timeofobservation,theVLAwastransitioningfromBnAto emissionbetweenthebrightcoreandthebrighterofthetwo
Aconfiguration,with27activeantennasonbaselinesranging lobes is found in all sources, while the fainter lobe is rela-
from 0.3 to 31.5 km. The X-band receiver provided 2 GHz tively isolated. On parsec scales, we find an isolated core in
bandwidth centered on 9 GHz, which was sampled with the J1435+3131whiletheothersshowextensionroughlyaligned
8-bit sampler with 2 s integration time. Requantizer gains withthekiloparsec-scalestructure.
wereappliedandthedatawereconvertedtoUVFITSformat
usingCASA(McMullinetal.2007). Thedatawerethencali- 3.1. J0953+2836
bratedinAIPSfollowingthestandardproceduresintheAIPS TheemissioninthetaperedVLAmapofJ0953+2836(Fig-
Cookbook and deconvolved, self-calibrated, and imaged in ure 1) spans 10.(cid:48)(cid:48)1 (measured at the second contour, follow-
DIFMAP (Shepherd et al. 1994). After initial calibration of
ing Scheuer (1995)), a projected length of 70.2 kpc. The
thephasecalibrators,cyclesofphase-onlyself-calibrationand brighter lobe lies along position angle (PA) 212◦, measured
CLEAN were repeated until a few times the residual root-
north through east. From the VLBA map, the parsec-scale
mean-square (rms) noise level was reached. Amplitude self- imageshowsextendedemissionwitharidgealongPA232◦.
calibration was then applied to determine the final complex
TheridgebrightensslightlytowardtheSW.Atwo-component
gains. To measure source positions, the gains derived from
Gaussianmodelfitsthevisibilitieswell,withtheSWcompo-
thephasecalibratorswereinterpolatedontothescienceobser-
nent brighter by a factor of 1.2. Identification of the parsec-
vations. AcircularGaussiancomponentmodelofthecorere-
scalecoreisuncertainanditisunclearwhetherthisisaone-
gionwasfittedtothevisibilitiesandthepositionofthebright-
ortwo-sidedjet.
est component is reported in Table 1, accurate to about 0.1
beam, or about15 mas. Forimaging, the sciencetarget data
3.2. J1435+3131
were cleaned and self-calibrated using the same procedures
usedforthephasecalibrators. The kiloparsec-scale emission in J1435+3131 (Figure 2)
VLBA observations were made on 8 Feb 2014 using the spans5.(cid:48)(cid:48)00, oraprojectedlengthof30.6kpc. Asharpbend
wideband C-band receiver configured to provide 256 MHz isevidentbetweenthecoreandtheNEkiloparsec-scalelobe.
total bandwidth in 8 sub-bands equally spaced over the A narrow, continuous trail of emission exits northward from
480 MHz band centered on 7.632 GHz with good weather thecore,thenbendsabout45◦tothenortheast,terminatingin
at all 10 antennas. The total integration time, listed in Ta- afaintknot. Astraightlineextendedfromthisknotalongthe
ble 1, was split into scans separated in time to provide good directionafterthebendiscloselyalignedwiththebrighterof
(u,v) coverage. In each scan, 49 s of full polarization data twohotspotsinthedisconnectedradiolobe. Theparsec-scale
were recorded as 2-bit samples for a total 2 Gbps data rate, imageshowsonlyacompactcore. Nokiloparsec-scaleemis-
withsciencetargetobservationsinterleavedwithobservations sionisevidentbetweenthecoreandthefainterSWradiolobe,
of a nearby phase reference. Observations at 4.9, 15.4, and whichhasasinglehotspot.
23.8GHzwerealsocarriedout,butwereportonly7.632GHz
total intensity results here. Full results from the VLBA pro- 3.3. J1722+5654
gram,includingpolarizationmeasurementsandtheotherfre- On kiloparsec scales, J1722+5654 (Figure 3) contains a
quencies, will be reported elsewhere. After correlation with
bright central core straddled by a linear structure along PA
theDiFXcorrelator(Delleretal.2007)usingourrefinedcoor- 47◦. The emission spans 4.(cid:48)(cid:48)08 which corresponds to a
dinates,thephase-referencedVLBAdatawereprocessedfol-
22.8 kpc projected length. The parsec-scale structure is also
lowingtheAIPSCookbook,applyinggainsolutionsfromthe linear, with three apparent emission regions along PA 60◦.
phasereferencestothesciencetargets. ACLEANmodelwas
The brightest parsec-scale emission is from the SW compo-
constructed,thenphase-onlyself-calibrationwitha10minute
nent; if this is identified as the core, then the parsec-scale
solution interval was applied and a final CLEAN was per-
morphology is a one-sided jet directed toward the brighter
formed. Weverifiedourfluxdensityscale,accuratetoabout
kiloparsec-scale lobe. This component is 2.3 times brighter
5%,bycomparingseveralcalibratorswithpreliminaryresults
thantheNEcomponent. Wenotethatthestructurecouldalso
from Effelsberg 100 m telescope observations made by the
beinterpretedasatwo-sidedjetwithafaintcoreatthecentral
Fermi-GST AGN Multi-frequency Monitoring Alliance (F-
emissionregion,inwhichcasethebrighterejectedcomponent
GAMMA;Fuhrmannetal.2007;Angelakisetal.2010).
isdirectedtowardthefainterkiloparsec-scalelobe. Misalign-
ments as large as 180◦ between the parsec- and kiloparsec-
3. RESULTS
scale jets have been seen (Kharb et al. 2010). However, the
The maps we obtained from our observations are shown
brightness temperature of the SW component is more than
in Figures 1, 2, and 3 and Table 2 lists quantities computed
20timeshigherthaneitherothercomponent,whichfavorsits
from our results. Using 1.4 GHz FIRST flux densities and
identificationasthecore(seeSection4.3).
our9GHzVLAfluxdensities,wehavedeterminedthenon-
simultaneous spectral index α. The formal uncertainty is
4. DISCUSSION
±0.04, assuming 5% uncertainties for the flux densities, not
4.1. Morphologies
accounting for non-simultaneity. These spectral indices are
lowerlimitsbecauseourhigherresolutionmapsmayresolve The parsec- and kiloparsec-scale morphologies of these
outmoreextendedemissionthanintheFIRSTdata. threesourcesaresimilartothosefoundinotherjettedAGN.
Onkiloparsecscales,allofthesesourcesshowsimilarmor- Theirkiloparsecscalemorphologiesresemblethosefoundin
phologies. Theemissionisdominatedbyabrightcorestrad- blazars, radio galaxies, and other radio-loud NLS1s (Cooper
dled by a pair of extended lobes. These lobes are edge- et al. 2007; Kharb et al. 2010; Doi et al. 2012). Extended
brightened,terminatinginhotspots.LikeinFRIIradiogalax- two-sidedemissionispresentinallthreecases,withonelobe
ies,theratiosofthehotspotseparationstothefullextentsof substantiallybrighterthantheother,presumablybecauseitis
the sources exceed 0.5 (Fanaroff & Riley 1974). Extended approaching us. These resemble FR II radio galaxies, with
Kiloparsec-scalejetsinradio-loudNLS1s 3
TABLE1
SourcepropertiesandrefinedJ2000coordinates.
Source NVSSName z MBH S1.4 MV R.A. Decl. PhaseReference VLBATime
(107M(cid:12)) (mJy) (hms) (◦(cid:48)(cid:48)(cid:48)) VLA/VLBA (min)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
J0953+2836 J095317+283601 0.659 6.3 47.94 −24.04 095317.102 283601.559 J0956+2515/J0954+2639 4.8
J1435+3131 J143509+313149 0.502 3.2 44.72 −23.01 143509.495 313147.864 J1435+3012/J1422+3223 9.8
J1722+5654 J172206+565452 0.426 2.5 39.83 −23.58 172206.029 565451.696 J1657+5705/J1727+5510 13.0
Note.—Columnsareasfollows:(1)IAUname(J2000);(2)correspondingsourceintheNRAOVLASkySurvey(NVSS,Condonetal.1998);(3)redshift
fromHewett&Wild(2010);(4)blackholemassfromYuanetal.(2008);(5)integrated1.4GHzfluxdensityfromWhiteetal.(1997);(6)absoluteV-band
magnitudecomputedfromSloanDigitalSkySurveyDataRelease10(Ahnetal.2014)gandrmagnitudesusingV=g−0.52(g−r)−0.03,afterJesteretal.
(2005)withnocorrectionforgalacticextinction;(7)-(8)newJ2000coordinatesdeterminedfromourVLAobservationswithanuncertaintyof±15mas;(9)IAU
name(J2000)ofphasecalibratorsusedforVLAandVLBAobservations;(10)totalVLBAintegrationtime.
TABLE2
Measuredproperties.
Source (cid:96)proj Sckoprce,9 Stkoptc,9 Ih9s,j α L1ex.4t Rhs logRv (βcosθ)hs (βcosθ)x Age Scpocre,7.6 Stpoct,7.6 TB
(kpc) (mJy) (mJy) (µJybeam−1) (WHz−1) (106y) (mJy) (mJy) (108K)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)
J0953+2836 70.2 12.0 18.8 158 −0.50 25.9 1.9 1.94 0.082 0.028 14–22 4.35 10.0 1.2
J1435+3131 30.6 7.8 11.7 324 −0.72 25.4 2.2 1.90 0.098 0.15 1.3–2.0 5.1 5.5 4.8
J1722+5654 22.8 7.9 12.2 688 −0.64 25.3 13 1.52 0.31 0.20 0.6–1.0 5.4 10.2 9.8
Note.—Columnsareasfollows:(1)IAUname(J2000);(2)projectedfullspanofextendedradioemission;(3)-(4)fluxdensityofthecorecomponentandthe
totalintegratedfluxdensityfromthe9GHzVLAdata;(5)peakintensityofthe9GHzemissionintheapproachinglobe;(6)non-simultaneous1.4–9GHzspectral
index;(7)extendedisotropicluminosity,extrapolatedfrom9GHzto1.4GHzandk-correctedassumingαext=−1;(8)ratioofpeakintensityofapproachingand
recedinglobes;(9)ratioofopticaltoradiocoreluminosity,k-correctedtotheemissionframeassumingαcore=0,αext=−1,andαoptical=−0.5;(10)projectedjet
speedcomputedfromRhs;(11)projectedjetspeedcomputedfromjet/counter-jetlengthratio;(12)kinematicageofsourceimpliedby(βcosθ)xforθ=10–15◦;
(13)7.6GHzVLBAcorefluxdensity;(14)total7.6GHzVLBAfluxdensity;(15)emissionframeVLBAcorebrightnesstemperature.
4 4
as) 2 as) 2
m m
(a) ( 0 (a) (
6 Decl. 2 3 Decl. 0
− 2
∆ ∆ −
4
4 − 2 4
6 −
− 6 4 2 0 2 4 4 2 0 2 4
c) 2 − − c) − −
rcse ∆R.A.(mas) (b) rcse 1 ∆R.A.(mas) (b)
a a
( 0 (
cl. cl.
De De 0
∆ 2 ∆
−
1
4 −
−
6 2
− 4 2 0 2 4 6 − 2 1 0 1 2
− − − − −
∆R.A.(arcsec) ∆R.A.(arcsec)
Fig.1.—NaturallyweightedmapsofJ0953+2836. Contoursincreaseby Fig.2.—NaturallyweightedmapsofJ1435+3131. Contoursincreaseby
√ √
factorsof 2. Atthisredshift,1(cid:48)(cid:48)=6.97kpc. (a)VLAmap(9GHz). To factors of 2. At this redshift, 1(cid:48)(cid:48) =6.12 kpc. (a) VLA map (9 GHz).
emphasizelow-surfacebrightnessextendedfeatures,aGaussiantaperwith Thefirstcontourisat30µJybeam−1, aboutfivetimesthemaprmsnoise
half-maximumat1.5×105wavelengthshasbeenapplied. Thefirstcontour of6µJybeam−1,andthemappeaksat8.39mJybeam−1.TheellipticalGaus-
isat50µJybeam−1,aboutthreetimesthemaprmsof17µJybeam−1,and sian restoring beam is shown (FWHM 0.236(cid:48)(cid:48)×0.228(cid:48)(cid:48)). (b) VLBA map
themappeaksat14.6mJybeam−1.TheellipticalGaussianrestoringbeamis (7.6GHz)ofthecentralbrightfeature.Thefirstcontourisat0.3mJybeam−1,
shown(FWHM0.911(cid:48)(cid:48)×0.786(cid:48)(cid:48)). (b)VLBAmap(7.6GHz)ofthecentral aboutthreetimesthemaprmsnoiseof0.1mJybeam−1,andthemappeaks
brightfeature. Thefirstcontourisat0.3mJybeam−1,aboutthreetimesthe at5.0mJybeam−1.TheellipticalGaussianrestoringbeamisshown(FWHM
map rms of 0.1 mJybeam−1, and the map peaks at 5.7 mJybeam−1. The 1.95mas×1.24mas).
ellipticalGaussianrestoringbeamisshown(FWHM1.82mas×1.39mas)
brightened hotspots near the outer edges of the kiloparsec- extended isotropic luminosities Lext, computed by subtract-
1.4
scalelobesevidentatleastontheapproachingside. Allthree ingthefittedcorefluxdensityfromthetotalfluxdensityand
sources are moderately core dominated at these scales, with scalingto1.4GHzassumingaspectralindexα =−1,liein
ext
about 2/3 of the total emission in the kiloparsec core. The thetransitionrangebetweenFRIandFRIIgalaxies,andfall
4 J.L.Richards&M.L.Lister
Assumingthestructureandevolutionofthesesourcesisin-
10
trinsicallysymmetric,wecanestimatetheprojectedjetspeed
intwoways. Thiscommonassumptionissupportedinthese
s)
a 5 particular cases by the alignment of the approaching parsec-
m
( scale jet and the longer kiloparsec-scale lobe (Arshakian &
(a) ecl. 0 Longair2000). Bothmethodshaveadegeneracybetweenthe
D
∆ speedandtheviewingangleθ,butassumingθ(cid:38)10◦,asseems
2 tobethecase,βcosθ∼βtowithinthelikelyaccuracyofour
5
− measurements. First, we consider the flux ratio between the
c) 1 10 5 0 hotspotsintheapproachingandrecedingjets. Ifabsorptionis
se ∆R.A.(mas) negligiblealongtheadditionalopticalpathtothecounter-jet,
c (b)
ar theexpectedratiois
(
∆Decl. 0 Rhs=(cid:32)11+−((ββccoossθθ))hs(cid:33)3−α, (1)
hs
1
−
where(βcosθ) istheprojectedspeedatwhichthelobesad-
hs
vanceatangleθ tothelineofsight. Forthiscalculation, we
−2 2 1 0 1 2 usetheratioofthepeakintensity(inµJybeam−1)betweenthe
∆R.A.(arcsec) − − jetandcounter-jetlobes, (Rhs=Ih9s,j/Ih9s,cj). Weobtainsim-
Fig.3.—NaturallyweightedmapsofJ1722+5654. Contoursincreaseby ilar results if we instead use the ratio between the flux den-
√
factorsof 2. Atthisredshift,1(cid:48)(cid:48)=5.58kpc. (a)VLAmap(9GHz). The sities obtained by fitting a Gaussian component model. For
first contour is at 21 µJybeam−1, about three times the map rms noise of J0953+2836andJ1722+5654,ifweinterprettheparsec-scale
7µJybeam−1,andthemappeaksat8.14mJybeam−1. TheellipticalGaus- jetsastwo-sided,thefluxdensityratiosof1.2and2.3imply
sian restoring beam is shown (FWHM 0.341(cid:48)(cid:48)×0.221(cid:48)(cid:48)). (b) VLBA map jet speeds βcosθ=0.04 and 0.18, comparable to those found
(7.6GHz)ofthecentralbrightfeature.Thefirstcontourisat0.2mJybeam−1,
atkiloparsecscales.
aboutthreetimesthemaprmsnoiseof0.07mJybeam−1,andthemappeaks
Wecanalsoexaminetheasymmetryinlengthbetweenthe
at4.8mJybeam−1.TheellipticalGaussianrestoringbeamisshown(FWHM
1.71mas×1.21mas). jetandcounter-jet. Ifthestructureisintrinsicallysymmetric,
differentiallighttraveltimewillcausetheapproachingjetto
alongtheL−ztrendreportedinKharbetal.(2010). appear longer than the receding jet (Banhatti 1980). In this
On parsec scales, the sources are compatible with one- case,theratio x≡(r −r )/(r +r )=(βcosθ) wherer and
j cj j cj x j
sided jet morphologies. The parsec-scale core region in r are the lengths of the jet and counter-jet, and (βcosθ) is
cj x
J1435+3131 is especially blazar-like, consisting only of a thejetspeedestimate. Thismethodgivescomparableresults
compactcore. Theothertwosourcesarecompatiblewithan tothebeamingratiomethod,sooverallwefindβcosθ∼0.03–
alternative interpretation as a faint or undetected core with 0.3. ThesecorrespondtoDopplerfactorsintherangeδ=1–
two-sidedemission. 1.5,whereδ=(1−β2)1/2/(1−βcosθ).
Dopplerbeamingwillincreasetheapparentbrightnesstem-
4.2. ViewingAngles perature of an emitting region relative to its intrinsic bright-
Two lines of reasoning suggest that the jet axes in these nesstemperature, TB,int, withtheobservedTB=δTB,int. Us-
sourcesareatrelativelysmallanglestothelineofsight.First, ing our VLBA data, we computed TB in the emission frame
the extended parsec-scale jets, where detected, are aligned from an elliptical Gaussian model as T =(1.22×1012 K)×
B
with the kiloparsec-scale jets (this would not be true for S(1+z)/(a a ν2) where ν is the observing frequency in
maj min
J1722+5654 if it is misaligned by about 180◦). Misalign- GHzandS,a ,anda arethefluxdensityinjanskysand
maj min
mentsduetoprojectioneffectsareexpectedtobemorecom- themajorandminoraxisFWHMs(inmas)ofthecorecompo-
monforsmallviewingangles,sothealignmentwefindsug- nent.Thebrightnesstemperatureswefindareallsubstantially
geststheviewinganglesarenotespeciallysmall,althoughour belowtheequipartitionlimitofabout1011K,compatiblewith
statisticsarelimited(Pearson&Readhead1988). a low Doppler factor (Readhead 1994). In each source, the
Second, we reach a similar conclusion from RV, the ratio presumed core has the highest brightness temperature of all
oftheobservedradiocoreluminositytotheopticalluminos- fittedcomponentsbyatleastafactorofeight.
ity. The latter acts as a proxy for the unbeamed, intrinsic The kinematic ages of these sources, computed assuming
emission. Motivated by Wills & Brotherton (1995), Kharb the approaching hotspots advanced outward steadily at their
etal.(2010)foundRV tobeagoodindicatorofviewingan- current speeds (β ∼ 0.03−0.3) at a viewing angle θ ∼ 10–
gle,wherelogRV=logLcore−logMabs−13.69withLcore the 15◦, are found to be a few times 105–107 y. These are in
1.4GHzcoreluminosityand M thek-correctedopticalV-
abs the range found for other extended radio-loud NLS1s, con-
bandmagnitude. Assumingaflatcorespectralindex,wefind
sistentwithNLS1sbeingmuchyoungerthanblazarsorradio
thatthelogR valuesfortheseNLS1s(1.5–1.9)areatthelow
V galaxies(Doietal.2012).
endofthedistributionforjet-selectedradio-loudAGN(e.g.,
the MOJAVE sample; Lister et al. 2013; Kharb et al. 2010). 5. CONCLUSIONS
This suggests the viewing angles of these NLS1s are similar
Extendedemissiononkiloparsecscaleswasdetectedinall
to the highest angles in the MOJAVE sources, roughly 10–
15◦(Savolainenetal.2010). threeofourtargets. Thisisperhapssurprisinginlightofthe
smallnumberofspatiallyextendedNLS1spreviouslyknown.
However, few have been observed with the requisite angular
4.3. JetSpeeds
resolution and sensitivity to detect the extensions we found
Kiloparsec-scalejetsinradio-loudNLS1s 5
here. Becauseourtargetswerearbitrarilyselectedfromapar- TheauthorsthankT.G.Arshakianforhelpfulsuggestions
entsampleofbright, radio-loudNLS1s, therewasnoreason and E. Angelakis and the F-GAMMA program for sharing
all three were especially likely to show extended emission. thepreliminarydataweusedtocheckourVLBAcalibration.
Thus,ourfindingssuggestthatotherNLS1sintheparentsam- This work was supported by the National Aeronautics and
ple are also likely to be extended. Observations of a larger Space Administration (NASA) through Fermi Guest Investi-
sample are needed to verify this and, if true, to investigate gator grant NNX13AO79G. The National Radio Astronomy
whetherthisisgenerallytrueofallradio-loudNLS1sorisa Observatory is a facility of the National Science Foundation
peculiarpropertyoftheparentsample. Themorphologiesof operatedundercooperativeagreementbyAssociatedUniver-
these sources on both kiloparsec and parsec scales are con- sities, Inc. This work made use of the Swinburne Univer-
sistentwiththepresenceofamildlyrelativisticjetatamod- sity of Technology software correlator, developed as part of
erately small (10–15◦) angle to the line of sight. The three theAustralianMajorNationalResearchFacilitiesProgramme
sources we observed and most previously known extended and operated under licence. This research has made use of
NLS1swhereresolutionpermittedclassificationshowFRII- theNASA/IPACExtragalacticDatabase(NED)whichisop-
like edge-brightened lobes. In contrast, Doi et al. (2014) re- eratedbytheJetPropulsionLaboratory,CaliforniaInstituteof
centlyreportededge-darkenedFRI-likeextendedradioemis- Technology,undercontractwiththeNationalAeronauticsand
sion in the NLS1 Mrk1239. The latter is radio quiet, while SpaceAdministration. ThisworkmadeuseofNedWright’s
theothersareradioloud,suggestingthatradioloudnessmay JavascriptCosmologyCalculator(Wright2006).
beconnectedtointrinsicsourceproperties,suchasjetpower,
ratherthanorientationeffects.
REFERENCES
Abdo,A.A.,etal.2009,ApJ,707,L142 Jester,S.,etal.2005,AJ,130,873
Ahn,C.P.,etal.2014,ApJS,211,17 Kharb,P.,Lister,M.L.,&Cooper,N.J.2010,ApJ,710,764
Angelakis,E.,Fuhrmann,L.,Nestoras,I.,Zensus,J.A.,Marchili,N., Komossa,S.,Voges,W.,Xu,D.,Mathur,S.,Adorf,H.-M.,Lemson,G.,
Pavlidou,V.,&Krichbaum,T.P.2010,inProceedingsoftheWorkshop Duschl,W.J.,&Grupe,D.2006,AJ,132,531
“FermimeetsJansky-AGNinRadioandGamma-Rays”,ed. Lister,M.L.,etal.2013,AJ,146,120
T.Savolainen,E.Ros,R.W.Porcas,&J.A.Zensus,arXiv:1006.5610 Maccarone,T.J.,Gallo,E.,&Fender,R.2003,MNRAS,345,L19
Anto´n,S.,Browne,I.W.A.,&Marcha˜,M.J.2008,A&A,490,583 Marconi,A.,Axon,D.J.,Maiolino,R.,Nagao,T.,Pastorini,G.,Pietrini,P.,
Arshakian,T.G.,&Longair,M.S.2000,MNRAS,311,846 Robinson,A.,&Torricelli,G.2008,ApJ,678,693
Banhatti,D.G.1980,A&A,84,112 McMullin,J.P.,Waters,B.,Schiebel,D.,Young,W.,&Golap,K.2007,in
Becker,R.H.,White,R.L.,&Helfand,D.J.1995,ApJ,450,559 AstronomicalSocietyofthePacificConferenceSeries,Vol.376,
Boller,T.,Brandt,W.N.,&Fink,H.1996,A&A,305,53 AstronomicalDataAnalysisSoftwareandSystemsXVI,ed.R.A.Shaw,
Boroson,T.A.2002,ApJ,565,78 F.Hill,&D.J.Bell,127
Calderone,G.,Ghisellini,G.,Colpi,M.,&Dotti,M.2013,MNRAS,431, Pearson,T.J.,&Readhead,A.C.S.1988,ApJ,328,114
210 Readhead,A.C.S.1994,ApJ,426,51
Condon,J.J.,Cotton,W.D.,Greisen,E.W.,Yin,Q.F.,Perley,R.A., Savolainen,T.,Homan,D.C.,Hovatta,T.,Kadler,M.,Kovalev,Y.Y.,
Taylor,G.B.,&Broderick,J.J.1998,AJ,115,1693 Lister,M.L.,Ros,E.,&Zensus,J.A.2010,A&A,512,A24
Cooper,N.J.,Lister,M.L.,&Kochanczyk,M.D.2007,ApJS,171,376 Scheuer,P.A.G.1995,MNRAS,277,331
Decarli,R.,Dotti,M.,Fontana,M.,&Haardt,F.2008,MNRAS,386,L15 Shepherd,M.C.,Pearson,T.J.,&Taylor,G.B.1994,inBulletinofthe
Deller,A.T.,Tingay,S.J.,Bailes,M.,&West,C.2007,PASP,119,318 AmericanAstronomicalSociety,Vol.26,BulletinoftheAmerican
Doi,A.,Nagira,H.,Kawakatu,N.,Kino,M.,Nagai,H.,&Asada,K.2012, AstronomicalSociety,987–989
ApJ,760,41 Whalen,D.J.,Laurent-Muehleisen,S.A.,Moran,E.C.,&Becker,R.H.
Doi,A.,Wajima,K.,Hagiwara,Y.,&Inoue,M.2014,ArXive-prints, 2006,AJ,131,1948
arXiv:1412.3308 White,R.L.,Becker,R.H.,Helfand,D.J.,&Gregg,M.D.1997,ApJ,475,
Fanaroff,B.L.,&Riley,J.M.1974,MNRAS,167,31P 479
Foschini,L.2012,inAmericanInstituteofPhysicsConferenceSeries,Vol. Wills,B.J.,&Brotherton,M.S.1995,ApJ,448,L81
1505,AmericanInstituteofPhysicsConferenceSeries,ed.F.A. Wright,E.L.2006,PASP,118,1711
Aharonian,W.Hofmann,&F.M.Rieger,574–577 Yuan,W.,Zhou,H.Y.,Komossa,S.,Dong,X.B.,Wang,T.G.,Lu,H.L.,&
Fuhrmann,L.,Zensus,J.A.,Krichbaum,T.P.,Angelakis,E.,&Readhead, Bai,J.M.2008,ApJ,685,801
A.C.S.2007,inAmericanInstituteofPhysicsConferenceSeries,Vol. Zhou,H.,Wang,T.,Yuan,W.,Lu,H.,Dong,X.,Wang,J.,&Lu,Y.2006,
921,TheFirstGLASTSymposium,ed.S.Ritz,P.Michelson,&C.A. ApJS,166,128
Meegan,249–251 Zhou,H.-Y.,Wang,T.-G.,Dong,X.-B.,Zhou,Y.-Y.,&Li,C.2003,ApJ,
Gliozzi,M.,Papadakis,I.E.,Grupe,D.,Brinkmann,W.P.,Raeth,C.,& 584,147
Kedziora-Chudczer,L.2010,ApJ,717,1243
Heinz,S.,&Sunyaev,R.A.2003,MNRAS,343,L59
Hewett,P.C.,&Wild,V.2010,MNRAS,405,2302