BAT AGN Spectroscopic Survey I: Spectral Measurements, Derived Quantities, and AGN ...

32 Pages·2017·3.44 MB·English

DRAFTVERSIONJULY27,2017
PreprinttypesetusingLATEXstyleemulateapjv.04/20/08
BATAGNSPECTROSCOPICSURVEYI:SPECTRALMEASUREMENTS,DERIVEDQUANTITIES,ANDAGN
DEMOGRAPHICS
MICHAELKOSS1,2,16,BENNYTRAKHTENBROT2,17,CLAUDIORICCI3,4,ISABELLALAMPERTI1,KYUSEOKOH1,SIMONBERNEY1,
KEVINSCHAWINSKI1,MISLAVBALOKOVIC´5,LINDABARONCHELLI1,D.MICHAELCRENSHAW6,TRAVISFISCHER6,NEIL
GEHRELS7,18,FIONAHARRISON5,YASUHIROHASHIMOTO8,DREWHOGG9,KOHEIICHIKAWA10,NICOLAMASETTI11,12,RICHARD
MUSHOTZKY9,DANIELSTERN13,EZEQUIELTREISTER3,YOSHIHIROUEDA14,SYLVAINVEILLEUX9,LISAWINTER15
DraftversionJuly27,2017
ABSTRACT
7
WepresentthefirstcataloganddatareleaseoftheSwift-BATAGNSpectroscopicSurvey(BASS).Weana-
1
lyzeoptical spectraof themajority ofAGN (77%, 641/836)detected basedon their14–195keVemission in
0
the 70-month Swift BAT all-sky catalog. This includes redshift determination, absorption and emission line
2
measurements,andblackholemassandaccretionrateestimatesforthemajorityofobscuredandun-obscured

l AGN (74%, 473/641) with 340 measured for the first time. With ∼90% of sources at z<0.2, the survey
u
represents a significant advance in the census of hard-X-ray selected AGN in the local universe. In this first
J
catalog paper, we describe the spectroscopic observations and datasets, and our initial spectral analysis. The
5
FWHM of the emission lines show broad agreement with the X-ray obscuration (∼94%), such that Sy 1-1.8
2
have N <1021.9cm−2, and Seyfert 2, have N >1021.9cm−2. Seyfert 1.9, however, show a range of col-
H H
umn densities. Compared to narrow line AGN in the SDSS, the X-ray selected AGN have a larger fraction
]
E of dusty host galaxies (Hα/Hβ >5) suggesting these types of AGN are missed in optical surveys. Using
H the [OIII]λ5007/Hβ and [NII]λ6583/Hα emission line diagnostic, about half of the sources are classified
asSeyferts, ∼15%resideindustygalaxiesthatlackanHβ detection, butforwhichtheupperlimitsonline
.
h emissionimplyeitheraSeyfertorLINER,∼15%areingalaxieswithweakornoemissionlinesdespitehigh
p quality spectra, and a few percent each are LINERS, composite galaxies, HII regions, or in known beamed
- AGN.
o
Subjectheadings:galaxies: active—galaxies: nuclei—quasars: general—blackholephysics
r
t
s
a
[ 1. INTRODUCTION cosmic X-ray background (CXB) spectrum (e.g., Comastri
et al. 1995; Treister et al. 2009; Draper & Ballantyne 2010;
A significant population of obscured active galactic nuclei
1 Ueda et al. 2014). The dusty and molecular torus is thought
(AGN) are expected from models and observations of the
v toberesponsibleforthisobscurationandisconsideredtobe
3 Electronicaddress:[email protected] aregionof1–100pcsizearoundthecentralaccretingsuper-
2 1InstituteforAstronomy,DepartmentofPhysics,ETHZurich,Wolfgang- massive black hole (SMBH) with high column densities of
1 Pauli-Strasse27,CH-8093Zurich,Switzerland >1023cm−2 that absorbs much of the soft X-ray (<10keV)
8 2EurekaScientific,2452DelmerStreetSuite100,Oakland,CA94602-
to optical radiation from the central engine and reemits it in
0 3017,USA
3Instituto de Astrof´ısica, Facultad de F´ısica, Pontificia Universidad the infrared (e.g., Pier & Krolik 1992). When the obscuring
.
7 Cato´licadeChile,Casilla306,Santiago22,Chile torus is blocking the line of sight, emission from the broad
0 4KavliInstituteforAstronomyandAstrophysics,PekingUniversity,Bei- lineregion(BLR)isblockedaswell. Evenifthelineofsight
jing100871,China
7 is blocked by the obscuring torus, some direct hard X-ray
5Cahill Center for Astronomy and Astrophysics, California Institute of
1 emission (>10keV) may still be visible because of the high
Technology,Pasadena,CA91125,USA
v: 6DepartmentofPhysicsandAstronomy,GeorgiaStateUniversity,Astron- penetration ability (≈90%, NH> 5 ≈ 1023cm−2) provided
i omyOffices,OneParkPlaceSouthSE,Suite700,Atlanta,GA30303,USA thelineofsightcolumndensityisnotheavilyCompton-thick
X 7NASAGoddardSpaceFlightCenter,Greenbelt,MD20771,USA (N >1025cm−2).
8DepartmentofEarthSciences,NationalTaiwanNormalUniversity,No. H
r
a 88,Sec.4,TingzhouRd.,WenshanDistrict,Taipei11677,TaiwanR.O.C
9DepartmentofAstronomyandJointSpace-ScienceInstitute,University Nebular emission lines observed in optical spectra probe
ofMaryland,CollegePark,MD20742,USA thephysicalstateoftheionizedgasingalaxiesandthuscan
10National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, beusedtotracethenuclearactivityof,forexample,acentral
Tokyo181-8588,Japan SMBHortheinstantaneousrateofstarformation(Osterbrock
11INAF-IstitutodiAstrofisicaSpazialeeFisicaCosmicadiBologna,via & Pogge 1985). Emission-line ratios have been turned into
Gobetti101,40129Bologna,Italy
powerfuldiagnostictools,notjustforindividualgalaxies,but
12Departamento de Ciencias F´ısicas, Universidad Andre´s Bello,
Ferna´ndezConcha700,LasCondes,Santiago,Chile formassivespectroscopicsurveys. Baldwinetal.(1981)first
13JetPropulsionLaboratory,CaliforniaInstituteofTechnology,4800Oak proposed the use of line diagnostic diagrams, which have
GroveDrive,MS169-224,Pasadena,CA91109,USA subsequentlybeendevelopedandrefinedinnumerousstudies
14DepartmentofAstronomy,KyotoUniversity,Kyoto606-8502,Japan (e.g.Veilleux&Osterbrock1987;Kewleyetal.2001;Shirazi
15AtmosphericandEnvironmentalResearch, 131HartwellAveNo. 4,
&Brinchmann2012).
Lexington,MA02421,USA
16Ambizionefellow
17Zwickyfellow While the narrow line region (NLR) provides a way to
18Deceased detectobscuredAGNinopticalsurveys,asignificantproblem
2 Kossetal.
isthepossiblepresenceofdustinthisregion. Dustisthought previousstudiesofBATAGNhavebeenlimitedtorelatively
to be destroyed in the BLR, but to extend throughout the smallsamples(N≈10−100AGN).Theinitial9-monthBAT
NLR(e.g.,Moretal.2009). Thisdustwillscatterandabsorb survey, which was based on observations from 2005-2006,
radiation and substantially change the level of ionization, wasstudiedintwodifferentfollow-upprograms(e.g.,Winter
complicatingAGNidentification. Anadditionalcomplication et al. 2010; Ueda et al. 2015). Other BAT optical spectro-
isthatinsomeAGN,burstsofstarformationcanoverwhelm scopic studies focused on smaller samples (N =11−75) of
the AGN photoionization signature (e.g., Moran et al. 2002; newlyidentifiedBATcounterparts,suchasfromthePalermo
Trump et al. 2015). Thus, the largest optical surveys that BAT catalogs (Parisi et al. 2009, 2012, 2014). Yet other
selectAGNareoftenincompletefornearbygalaxiesbecause studies focused on small samples of AGN identified with
of obscuration or difficulty in detecting lower-luminosity INTEGRAL above 20keV, with some overlap with the BAT
AGNingalaxieswithsignificantstarformation. AGN (e.g., Masetti et al. 2013). While these AGN studies
madesignificantadvancesincounterpartidentification,most
An all-sky survey in the ultra-hard X-ray band (14– didnotprovidemeasurementsofblackholemassesandnone
195keV) provides an important new way to address several measuredstellarvelocitydispersionsinobscuredsources.
fundamentalquestionsregardingblackholegrowthandAGN
physics, using a complete sample of AGN. The Burst Alert Thegoalofthisproject,theSwift-BATAGNSpectroscopic
Telescope (BAT) instrument on board the Swift satellite has Survey, or BASS, is to complete the first large (N (cid:39)500)
surveyed the sky to unprecedented depth, increasing the sample of ultra-hard X-ray selected AGN with optical spec-
all-sky sensitivity by a factor of ≈20 compared to previous troscopy and measured black holes masses using the deep
satellites, such as HEAO 1 (Levine et al. 1984). This has catalogsthatdetectmanymorefaintAGN.Thisenablesnew
raisedthenumberofknownhardX-raysourcesbymorethan insights into the nature and geometry of the obscuring torus
a factor of 20 to 836 AGN (Baumgartner et al. 2013). The andNLR;ameasurementofblackholegrowthinarelatively
majorityoftheBATAGNarenearby,withamedianredshift complete sample of AGN; and serves as a low-redshift
of z(cid:39)0.05 (among the sources with previously known red- benchmarkfordeepX-raysurveysofdistantAGN.
shifts). This sample is particularly powerful since emission
in the 14–195 keV BAT band is relatively undiminished up In this first paper of a series, we define the AGN sample
to obscuring columns of > 1024cm−2. BAT is therefore and provide the results of a set of measurements focusing
sensitive to heavily obscured objects where even hard X-ray on emission line diagnostics, black hole masses, and accre-
surveys (2–10keV) are severely reduced in sensitivity. As tion rates. One of the early science results derived from our
the brightest AGN in the sky above 10keV, BAT-detected analysis—a comparison of X-ray to optical line emission—
AGNprovideanimportantlowredshifttemplateastheyhave was presented in Berney et al. (2015). In Section 2, we dis-
similar luminosities to AGN detected in deep, small area cuss the parent sample of Swift BAT selected AGN and the
X-ray surveys which focus on higher redshift AGN (z>1, differentopticaltelescopes,instrumentalsetups,andbasicre-
see e.g., Brandt & Alexander 2015, and references therein). duction procedures used to collect the spectroscopic dataset
Finally, BAT-detected AGN are also of renewed interest weuse.Wedescribethehostgalaxytemplatefitting,emission
because of a large NuSTAR snapshot program, targeting linefitting,measurementsofblackholemassesandbolomet-
>200 obscured AGN from Swift BAT (e.g., Balokovic´ et al. ricluminosityinSection3. Finally,theoverallAGNspectro-
2014; Brightman et al. 2015; Koss et al. 2015, 2016a; Ricci scopic properties and initial scientific results and follow-up
etal.2016). projects are described in Section 4. Throughout this work,
we use a cosmological model with Ω = 0.7, Ω = 0.3,
Λ M
Bright AGN at lower redshifts (z < 0.2) offer the best and H = 70kms−1Mpc−1 to determine cosmological dis-
0
opportunity for high sensitivity studies of the SMBH ac- tances. However, for the most nearby sources in our sample
cretion rate which requires accurate measurements of the (z<0.01), we use the mean of the redshift independent dis-
SMBH mass and AGN bolometric luminosity. Nearby tance in Mpc from the NASA/IPAC Extragalactic Database
optical spectroscopic studies can provide estimates of the (NED),wheneveravailable19.
black hole mass through measurements of the velocity
dispersions of either the BLR gas and/or the hosts’ stars for 2. PARENTSAMPLEANDDATA
themajorityofAGN.TheemissionintheBATbandprovides In this section we discuss the parent X-ray AGN sample
an obscuration-free estimate of the bolometric luminosity. aswellasthedifferentdatabasesanddedicatedobservations
Hence the combination of optical spectroscopy and hard usedtoconstructourspectroscopicdataset.
X-rayemissionfromtheBATbandprovidestheaccretionrate
(in terms of the Eddington rate, L/LEdd) for a large sample 2.1. The70-MonthSwiftBATCatalogandX-rayData
ofAGN.Blackholemassmeasurementsusingreverberation
TheBATsurveyisanall-skysurveyintheultra-hardX-ray
mapping (e.g., Bentz et al. 2009), or OH megamesars (e.g.,
range (>10keV) that, as of the first 70 months20 of opera-
Staveley-Smithetal.1992)offermoreprecisemeasurements
tion has identified 1210 objects (Baumgartner et al. 2013).
of black hole masses; however, these techniques can only
Because of the large positional uncertainty of BAT (≈ 2(cid:48))
be applied to a small (N <50) AGN sample that lacks the
higher angular resolution X-ray data for every source from
uniform selection criteria to understand the AGN population
Swift-XRT or archival data have been obtained, providing
asawhole. Thus, astudyoftheBATAGNsampleprovides
associationsfor97%ofBATsources. Fromthiscatalog, we
anexcellentopportunitytostudyblackholegrowthinalarge
sampleofuniformlyselectednearbyAGN.
19TheNASA/IPACExtragalacticDatabase(NED)isoperatedbytheJet
Propulsion Laboratory, California Institute of Technology, under contract
Despite the improvement in sensitivity above 10 keV, withtheNationalAeronauticsandSpaceAdministration
20http://heasarc.gsfc.nasa.gov/docs/swift/results/bs70mon/
BASS-I 3
exclude BAT sources lacking a soft X-ray counterpart, and
those associated with galaxy clusters and Galactic sources.
In addition, we exclude M82, which is a very nearby star
forming galaxy detected by Swift BAT without the presence Masetti SAAO
ofanAGN.Thisleaves836BAT-detectedAGN. Palomar 37 46 KPNO
35 52
Almost all of the host galaxy AGN counterparts used
Gemini
in this study (99%, 632/641) are based on the published 29 Perkins
counterparts in Baumgartner et al. (2013) paper which Marziani 52
18
was based on Swift/XRT, XMM-Newton, Chandra, Suzaku, CTIO
14
and ASCA followup. In Baumgartner et al. (2013) the Torrealba 14
host galaxy counterpart of the BAT AGN was determined FAST 10
using the brightest counterpart above 3 keV typically from LaUnHdi 4 56 62 Parisi
Swift/XRTobservations,withintheBATerrorradius(≈3(cid:48). In LiAckPO 4
only nine cases we use updated galaxy counterparts based
on subsequent published studies. These differences are
associatedwiththeupdatedcounterpartsforSWIFTJ1448.7- 142 112
4009 and SWIFTJ1747.7-2253 provided in Masetti et al.
SDSS 6DF
(2013); SWIFTJ0634.7-7445, SWIFTJ0654.6+0700,
and SWIFTJ2157.4–0615 found in Parisi et al. (2014);
SWIFTJ0632.8+6343, SWIFTJ0632.8+6343 and SWIFT
J1238.6+0928 provided in the updated INTEGRAL catalog
ofMaliziaetal.(2016),andfinallySWIFTJ0350.1-5019,we
usethecounterpartfromRiccietal.,submitted(ESO201-4). FIG.1.—Sourcesof641uniqueAGNspectrausedfortheBASScatalog
AnotherissueisthatsomeBATAGNcounterpartshostdual takenfrompublicsurveysandtargetedcampaigns.
AGN (Koss et al. 2016b), however, the median value of
the(Lint )ratiobetweenthedualAGNsis11(Kossetal. of the spectral region covering all the lines from Hβ to
2012),2−so10thkeeVmajorityoftheemissionintheBATdetectionis [SII]λ6717,6731 (i.e., 4800–7000A˚). We then selected
based on signal-to-noise in the continuum for fitting of
typically coming from a single AGN. A full review of all of
absorption lines and stellar population templates. Each
theAGNgalaxycounterpartidentificationsanddualAGNis
spectrumwasvisuallyinspectedtoavoidanycasesthatmay
providedinRiccietal.,submitted.
be problematic for fitting (e.g., bad sky subtraction or noise
spikes). This process reduced the number of spectra from
We then cross-match this sample to the Roma Blazar
972 spectra including duplicates to 641 unique spectra. Of
Catalog(BZCAT)catalog(Massaroetal.2009)andidentify
these641uniquespectra,33%(209/641)werefromtargeted
11% (96/836) of AGN as possibly beamed sources, such as
observationsand67%(433/641)werepartofarchivesorpre-
blazarsorflatspectrumradioquasarswhereDopplerboosting
viouslypublishedpapers. Asummaryofalltheobservational
may amplify the non-thermal emission including the hard
setupsisshowninTable1andFig.1. Themaindataproducts
X-rays. As the Roma BZCAT authors note, classifications
of beamed AGN in their catalog have significant uncertainty areavailableonline21.
because only the very brightest AGN have the necessary
polarimetricobservationsordetectionsofcompactcoresand
superluminal motions using high resolution radio imaging 2.2.1. ArchivalPublicData
combinedwithvariabilitystudies. Alargefractionofthedataweusearedrawnfromseveral
largepubliccatalogsofopticalspectra. Herewereportonthe
AlloftheAGNintheBATsurveyhavebeenanalyzedus- number of best spectra that were used for each AGN in the
ing X-ray observations spanning 0.3–195keV. This includes catalog. The largest was from the Sloan Digital Sky Survey
homogeneous model fitting using some of the best avail- (York 2000), with 142 sources from data release 12 (DR12,
able soft X-ray data in the 0.3−10keV band from XMM- Alam et al. 2015). For 112 additional sources, the spectral
Newton,Chandra,Suzaku,orSwift/XRTandthe14–195keV measurements are based on archival optical spectra obtained
band from Swift BAT. This analysis provides measurements as part of the final data release for the 6dF Galaxy Survey
of the obscuring column (NH) and intrinsic X-ray emission (6dFGS, Jones et al. 2009). The main characteristics of the
(Lint ).FulldetailsoftheX-rayanalysisandfittingmea- 6dFGS survey are reported in Jones et al. (2004). We note
2−10keV
surements are provided in separate publications (Ricci et al. that, unlike the SDSS spectra, the 6dF spectra are not flux
2015,Riccietal.,submitted.). calibrated on a nightly basis and therefore we have not used
themforbroadlineblackholemassmeasurements.
2.2. OpticalSpectroscopicData
ThegoaloftheBASSsampleistousethelargestavailable Wealsousedpubliclyavailablespectrafromsmallercom-
opticalspectroscopicsampleofSwiftBATsourcesusingded- pilations of AGN, as long as they were flux and wavelength
icated observations and public archival data. In many cases, calibrated and the spectral resolution was well determined.
there were many duplicate observations of the same source. ThespectralresolutionsweremeasuredbasedontheFWHM
Insuchcases,weselectthesinglebestspectrumforlinemea- ofskylinesinthespectrawhenpossible. For46sources,the
surements for each AGN in our catalog from a single tele- spectral measurements are based on optical spectra obtained
scope.
For line fitting, our first criterion was full coverage 21http://www.bass-survey.com
4 Kossetal.
TABLE1
SUMMARYOFINSTRUMENTALSETUPS
Slit Resolution Totalrange Velocitydispersionfitrange
Telescope Inst. Total Grating
Width((cid:48)(cid:48)) FWHM[A˚] [A˚] [A˚]
SDSS SDSS 142 2,3 2.76 3900–8000 3900–7000
UKSchmidt 6dF 112 600V,316R 6.7 5.75 3900–7000 3900–7000
Perkins1.8m Deveny 52 300 2 5.43 3900–7500 3900–5500
KPNO2.1m Goldcam 36 32 2 7.4 4200–8800 4400–5500
16 26,35 2 3.3 3900–8500 3900–7000
SAAO1.9m 300 46 7 2 5.00 4000–7500 4600–7000
Hale200–inch DBSP 20 600 1.5 4.4,5.8 3900–7000 3900–5500,8450–8700
15 600 2 4.8,6.8 3900–7000 3900–5500,8450–8700
Gemini8.1m GMOS 21 B600 1 4.84 4000–7000 4000–7000
5 0.75 3.75 4300–7000 4300–7000
3 0.75 3.72 4000–7000 4000–7000
CTIO1.5m R–C 10 26,35 2 4.30 3900–7500 3900–7000
2 47 2 3.10 5200–7500 5200–7000
2 36 2 2.20 4500–5500 4500–5500
Tillinghast1.5m FAST 10 300 3 5.5 3700–7500
UH2.2m SNIFS 5 300 2.4 5.80 3200–7000 3900–5500
APO3.5m DIS 4 B400,R300 1.5 7.00 3900–7000 3900–5600
Shane3m Kast 4 600,830 2 4.0,3.2 3900–7000 3900–7000
using the SAAO telescope, in an effort to study all of the spectrograph, through a 2(cid:48)(cid:48) slit. We used two different
earlier9monthsurveyofBATAGN(Uedaetal.2015). We setups for observing. The first set of observations was from
used37spectrafromseveralopticalspectroscopicstudiesof Winter et al. (2010) and used the grating 26new, which
newly identified AGN from INTEGRAL which overlap with covers 3660–6140A˚ on the blue side, and grating 35, which
theBATsampleinthisstudy(Masettietal.2004,2006c,d,a,b, covers4760–7240A˚ ontheredside. Boththesesetupshada
2008a,b, 2010, 2012, 2013). For 18 spectra, we used the spectralresolutionof3.3A˚.Additionally,aseparateGoldcam
lowredshiftAGNatlasofMarzianietal.(2003), whichwas
program(PIM.Koss)usedasinglelowerdispersiongrating,
obtainedusingseveral2m-classtelescopes.Opticalspectraof
grating32,whichcoveredalargerwavelengthrangethanthe
14highredshiftAGNintheBATsamplewerefromobtained
higherdispersiongratings(4280–9220A˚),ataspectralreso-
through the Monitoring of Jets in Active Galactic Nuclei
lution of 6.7A˚. There were also programs using the Perkins
withVLBAExperiments(MOJAVE)project, targetingAGN
1.8m telescope and DeVeny Spectrograph at the Lowell Ob-
selectedat2cm(Torrealbaetal.2012). 10sourcesarebased
servatoryandCTIO1.5mRCspectrograph(PIM.Crenshaw).
onflux-calibratedopticalspectraofbroadlineAGNobserved
withFAST(Landtetal.2007). Wealsousedspectraobtained
We also had optical spectroscopic programs using larger
tofollowupthePalermoBATcatalog,whichhasproducedits
telescopes. For 29 sources, the spectral measurements
own BAT AGN catalog, which has significant overlap with
were obtained with the Gemini North and South telescopes,
thissample(N=62;Parisietal.2009,2012,2014). Finally,
using the twin Gemini Multi-Object Spectrograph (GMOS)
we use 6 sources from an early study by Landi et al. (2007)
instruments. The GMOS observations took place between
from the first 3-month BAT catalog (Markwardt et al. 2005)
2009 and 2012, as part of nine different observing programs
whicharealsodetectedinthe70-monthBATsample.
(P.I. M. Koss, E. Treister, and K. Schawinski). In this
study we use data from Gemini programs GN-2009B-Q-
114, GN-2010A-Q-35, GN-2011A-Q-81, GN-2011B-Q-96,
2.2.2. TargetedSpectroscopicObservations
GN-2012A-Q-28, GN-2012B-Q-25, GS-2010A-Q-54, and
The other source of spectra for our analysis are dedicated GS-2011B-Q80. Most of these programs focused on dual
spectroscopic observational campaigns of BAT AGN, taken AGN, but covered the brighter BAT sources with the slit
over the last several years, using a variety of telescopes and aligned with the secondary galaxy nucleus. We used two
instruments. In terms of the data reduction and analysis, spectral setups for observations. The majority of targets
however, we have maintained a uniform approach. All the were observed using the B600-G5307 grating with a 1(cid:48)(cid:48) slit
spectra were processed using the standard tasks in IRAF for in the 4300–7300A˚ wavelength range, providing a spectral
cosmic ray removal, 1-d spectral extraction, wavelength, resolution of 4.8A˚. The Gemini/GMOS IRAF pipeline was
and flux calibrations. The spectra were all taken as longslit
used for wavelength calibration, spectro-spatial flat-fielding,
observations, except for observations taken with an IFU on
cosmicrayremoval,andfluxcalibration.
the University of Hawaii (UH) 2.2m telescope. In all cases,
the spectral resolutions listed were measured based on the
WeusedthePalomarDoubleSpectrograph(DBSP)onthe
FWHM of sky lines in the spectra or arc lines taken for
Hale 200-inch Hale telescope for 35 targets. These AGN
wavelength calibration. The spectra were flux calibrated wereobservedaspartoftheNuSTARBATsnapshotprogram,
using standard stars, which were typically observed once
focusing mostly on Seyfert 2 AGN (P.I. F. Harrison and D.
per night. Basic information about these observations are
Stern). The observations were performed between 2012 Oc-
giveninTable1, andthefollowingprovidesamoredetailed
toberand2015February. Themajorityofobservationswere
accountofthesededicatedcampaigns.
takenwiththeD55dichroicandthe600/4000and316/7500
gratings using a 1.5(cid:48)(cid:48) slit, providing resolutions of 4.4A˚ and
We had several large, multi-year programs on small 1-2m 5.8A˚,respectively.
telescopes. For 52 sources, the spectral measurements were
Finally, we had smaller programs using the 3.5m Apache
taken with the KPNO 2.1m telescope and the GoldCam
BASS-I 5
Pointtelescope(APO,4sources), the3mShanetelescopeat observationbeforefitting.
theLickobservatory(4sources),andtheUH2.2mtelescope
(5sources). TheAPOobservationsusedtheB400andR300 We fitted the spectra in the wavelength region 3900–
gratingswitha1.5(cid:48)(cid:48)slit,providingwavelengthcoveragefrom 7000A˚, if this entire range was covered by the given
3570–6230A˚ intheblueand5190–9810A˚ intheredandres- spectrum. This range covers the Ca H+Kλ3935,3968
olution of 7A˚. The Lick observatory Kast spectrograph was and MgIλ5175 absorption features. For some spectra
used with blue and red coverage between 3900–7000A˚ and the velocity dispersion was estimated only based on the
spectralresolutionof4A˚.OntheUHtelescope,weusedthe MgI absorption line, because of a lack of blue wavelength
SuperNova Integral Field Spectrograph (SNIFS). SNIFS has coverage (e.g., spectra taken with KPNO and grating 32,
a blue (3000–5200A˚) and red (5200–9500A˚) channel, with Perkins,andsomeGeminigratings). Toavoidcomplications
a resolution of 5.8A˚ in the blue and 8.0A˚ in the red. The withdiscontinuitiesanddispersionchangesinspectrawhich
have both blue and red setups, only the blue channel spectra
SNIFS reduction pipeline, SNURP, was used for wavelength
calibration, spectro-spatial flat-fielding, cosmic ray removal, (3800–5500A˚) were used to estimate velocity dispersion,
andfluxcalibration(Baconetal.2001;Alderingetal.2006). focusingontheCaH+KandMgIabsorptionlines. Theonly
Askyimagewastakenaftereachsourceimageandsubtracted exceptionisthedual-channelSDSSdata,wherethefullrange
fromeachIntegralFieldUnit(IFU)observation. Theextrac- was fit. Whenever available, we also fitted the CaII triplet
tionaperturewas2.4(cid:48)(cid:48)indiameter. spectralregion(8450–8700A˚).
3. SPECTROSCOPICMEASUREMENTS Wemodifiedtheppxf-kinematics-example-sdsscode
Weperformedthreeseparatesetsofspectralmeasurements to measure stellar kinematics in our sample. Table 3 shows
with the 641 BASS spectra. The general properties of each theemissionandbrightnightskylinesthatweremasked.The
AGN and the details of the optical spectra are presented in codeautomaticallyappliesamaskforseveralbrightemission
Table2. Inthefirststep,eachAGNhostgalaxywasfitusing lines: Hδ, Hγ, Hβ, [OIII]λ5007, [OI]λ6300, [NII]λ6583,
galaxystellartemplates(Section3.1)andthevelocitydisper- Hα, and [SII]λ6717,6731. We masked sky lines at λ5577,
sionwasmeasuredwhenpossible(Section3.1.1). Theemis- λ6300,λ6363,andλ6863. Wealsomasktheregionaround
sion lines were then fit (Section 3.2) using narrow compo- theCaHλ3968line,becauseofoverlapwiththeHε λ3970
nentsandbroadcomponentswhenneeded.Blackholemasses and the [NeIII]λ3968 emission lines (see, e.g., Greene &
inAGNwithbroademissionlinesweremeasuredbyamore Ho2005a). Wehavealsomaskedtheregionsurroundingthe
detailed fit to the spectral regions that include the broad Hβ NaI line, since it may be affected by interstellar absorption.
and/or broad Hα lines, or the MgIIλ2798 and CIVλ1549 Finally, we masked regions affected by sky emission lines.
lines in high redshift sources (Section 3.3). Finally, we esti- The width of these emission lines masks was set to 2400
matedthebolometricluminosity(L )fromtheX-raylumi- kms−1. Forthebroad-lineAGN,weuseawidermask(3200
bol
nositytoestimatetheaccretionrates(Section3.4). kms−1) for the Balmer lines (Hα, Hβ, Hγ, Hδ), in order to
mask the broad emission components. This allowed us to
3.1. GalaxyTemplateFitting measure the velocity dispersion for some AGN with broad
WeusethepenalizedPiXelFittingsoftware(pPXF;Cappel- emissioninHα,butnarrowHβ.
lari&Emsellem2004)tomeasurestellarkinematicsandthe
centralstellarvelocitydispersion(σ ). Thismethodoperates
∗
in pixel space and uses a maximum penalized likelihood 3.1.1. VelocityDispersionMeasurements
approach for deriving the line-of-sight velocity distribution Fig. 2 summarizes the results of the stellar velocity
(LOSVD) from kinematic data (Merritt 1997). As a first dispersion measurements and individual measurements are
step, the PPXF code (version 5.1.9) creates a model galaxy foundinTable4. ∆σ∗ denotestheerrorinσ∗. Wewereable
spectrumGmod(x)byconvolvingempiricalstellarpopulation to achieve a reliable velocity dispersion measurement, with
models by a parametrized LOSVD. Then it determines the ∆σ <60kms−1, in 201 of the 641 (31.3%) galaxies in our
∗
best-fitting parameters of the LOSVD by minimizing the sample. FortheseAGN,thestellarcontinuumwassubtracted
value of χ2, which measures the agreement between the prior to emission line fitting (discussed below). For most
model and the observed galaxy spectrum over the set of AGN with broad Hβ, the AGN continuum contaminated the
reliabledatapixelsusedinthefittingprocess. Finally, PPXF host galaxy and stellar absorption lines, limiting reliable σ
∗
usesthe“bestfitspectra”tocalculatethevelocitydispersion measurementstoonly13type1.2–1.8AGN.Additionally,in
andassociateduncertaintyfromtheabsorptionlines. 166 sources the signal-to-noise ratio and spectral resolution
weretoolowtorobustlyidentifytheabsorptionlines.
ThePPXFcodeusesalargesetofsinglestellarpopulations
to fit each galaxy spectrum. We used the templates from Four authors (MK, BT, SB, and IL) visually inspected
the Miles Indo-U.S. Catalog (MIUSCAT) library of stellar the fit of the stellar continuum and absorption lines, and
spectra (Vazdekis et al. 2012). The MIUSCAT library of assigned a quality flag to each spectrum. In our sample
stellar spectra contains ≈1200 well-calibrated stars covering we have 128 spectra with flag 1 and 73 spectra with flag 2,
the spectral region of 3525–9469A˚ at a spectral resolution which both designate reliable measurements. More details
of 2.51A˚ (FWHM). These spectra are then computed into andexamplesofthesequalityflagsaregivenintheAppendix
stellar libraries with an IMF slope of 1.3, and the full range (Section 6.1). Generally, the σ∗ uncertainty measured by
ofmetallicities(M/H =−2.27to+0.40)andages(0.03–14 PPXF for flag 1 fits is typically small ((cid:104)∆σ∗(cid:105)(cid:39)12kms−1).
Gyr). Thesetemplateshavebeenobservedathigherspectral Flag 2 fits have somewhat worse quality fits, judged from
resolution (FWHM=2.51A˚) than the AGN observations and our visual inspection, consistent with PPXF measurements
are convolved in PPXF to the spectral resolution of each ((cid:104)∆σ∗(cid:105)(cid:39)27kms−1), but the Ca H+K and MgI absorption
6 Kossetal.
300 Table9forbothHβ andHα.
1
0.4 Type 250 allFsopre6ctDraFtsopceoctnrvae,rtthmeesausruvereydacpopulinetdsatostihneglceocrarelicbtrsaptieocntrtaol

shape,butanightlyfluxcalibrationwasnotapplied. For6DF
N
S emissionlinemeasurements,wehavecalculatedaroughflux
0.3 w 200N calibration factor for 6DF spectra based on 12 overlapping
Fraction0.2 Flag 1 g 2 Lo 110500 Total AG sapsseIuncmtreaeascinh1dcoitsftiasthneetqAuthaGlrNetoe(7zs.p>6e9c0t×r.0a1l50)fi−wt1t7iintehgrgthrsee−g1SicoDmnSs−,S2.AwTAeh−ia1sd.foapcttoar
a power-law fit (1st order) to account for the (local) AGN
0.1 Fl med wave 50 cthoenteinmuiusmsioanndlinaess.eriWeseodfeGfinaeusasinanemcoismsipoonnelinntes tdoetmecotidoenl
ea o when we reach a S/N >3 over the line with respect to the
B N
noise of the adjacent continuum, and otherwise list upper
0.0 0
detectionlimits. Toestimateerrorsinlinefluxes andwidths
(intermsofFWHM),weuseasimplere-samplingprocedure
FIG.2.— Measurements of velocity dispersion from our sample using
PPXF. For31%ofspectra(201/641),wehavearobustmeasurementofσ∗. that adds noise based on the error spectrum and reruns the
128spectrahaveagoodfitandsmallerrorinthevalueofσ∗ (flag1). 73 fitting procedure 10 times. The (fractional) flux uncertainty
spectrahaveworsefits,butthevalueofσ∗issufficientlygoodbasedonvi- for the [OIII] emission line is typically less than 1%. We
sualinspection(flag2). Theremainingcategories(dashedhistograms)have
featuresthatpreventedmeasurements.For207spectrawecouldnotmeasure use the narrow Balmer line ratio (Hα/Hβ) to correct for
σ∗becauseofAGNcontaminationtothestellarcontinuum.For166spectra, dust extinction, assuming an intrinsic ratio of RV =3.1 and
thesignal-to-noiselevelofthecontinuumorthegratingresolutionwerenot the Cardelli et al. (1989) reddening curve. In the case of a
sufficienttomeasuretheabsorptionlines.Asmallnumberofofsourceswere
Hβ non-detection, we assume the 3σ upper limits for the
blazarswithfeaturelesscontinuum. Finally,wealsohadasmallnumberof
sourceswithnocoverageofkeyabsorptionlinefeaturessuchasCaH+K, extinctioncorrection. WhenneitherHβ orHα isdetectedwe
MgI,ortheCaIItripletregions. presentthefluxesasmeasured.
linesarestillwellfit. For the Hβ spectral region, we fit the HeIIλ4686, Hβ,
[OIII]λ4959,and[OIII]λ5007lines. Thewidthsofthenar-
For AGN with reliable measurements of σ∗ we calculated rowlinesaretiedwithanallowedvariationof±500kms−1.
the black hole mass, MBH, using the MBH−σ∗ relation. We Thecentralwavelengthofthenarrowlineregionisdefinedby
usetherelationfromKormendy&Ho(2013): ajointfitofallthenarrowlineswherethewavelengthsepara-
(cid:18)M (cid:19) (cid:18) σ (cid:19) tionofalllinesistied. Theintensityof[OIII]λ4959relative
log BH =4.38×log ∗ +8.49. (1) to [OIII]λ5007 is fixed at the theoretical value of 2.98
M(cid:12) 200kms−1 (Storey & Zeippen 2000) and the intensity of [NII]λ6548
The slope of this relation is shallower than the slope of the relative to [NII]λ6583 is set to the theoretical value of
relation from McConnell & Ma (2013), who report a value 2.96 (Acker et al. 1989). For the Hβ complex, we use the
of 5.64, and is consistent with the slope of the relation from 4660–4750A˚ (exceptaroundHeII)and5040–5200A˚ regions
Gu¨ltekinetal.(2009). Asmallnumberofsourceshavedirect forcontinuumdetermination. WithintheHα spectralregion,
measurementsofblackholemasses,eitherfromreverberation we fit the [OI]λ6300, [NII]λ6548, Hα, [NII]λ6583, and
mapping(39)orOHmegamasers(8),whichwehaveadopted [SII]λ6716, and [SII]λ6731 lines. Here too, the widths
andtabulatedwheneveravailable. of the narrow lines are tied, with an allowed variation of ±
500kms−1and the systemic redshift is determined from all
3.2. EmissionLineMeasurements narrow lines. In the case of a non-detection of the narrow
Hα or[SII]λ6717,6731line(i.e.,duetoaverystrongbroad
Wefitemissionlinesinoursampleofopticalspectrausing
Hα component or weak narrow emission lines), we use the
an extensive spectroscopic analysis toolkit for astronomy,
FWHMof[OIII]λ5007toconstrainthewidthsofthenarrow
PySpecKit, which uses a Levenberg-Marquardt algorithm
linesintheHα region. Therelativestrengthsof[NII]λ6548
forspectralfitting(Ginsburg&Mirocha2011). Allemission
and [NII]λ6583 lines are fixed at 1:2.94. To estimate the
line fits were visually examined by five authors (MK, BT,
continuum for the Hα complex, we use the wavelength
SB, KS, and IL) to verify proper fitting, and to adjust
regions 5800–6250A˚ and 6750–7000A˚. Finally, within the
some subtle parameters. We implement separate methods
for fitting sources with only narrow lines and for sources [OII]spectralregion,wefitthe[NeV]λ3346,[NeV]λ3426,
with broad lines. For narrow-line sources, we first fit and [OII]λ3727, [NeIII]λ3869, and [NeIII]λ3968 lines. The
subtract a host stellar component, to remove the galaxy continuum around the [OII] spectral region is usually more
complicated to fit due to a non-linear shape or because it
continuum and stellar absorption features, as described in
lies near the blue edge of the wavelength coverage. To fit
Section 3.1. We then separately fit three spectral regions,
focusing on the [OII] (3300–4000A˚), Hβ (4650–5050A˚), this blue continuum, we use the region between 3300A˚ and
andHα (6250–6770A˚)emissionlines. Allmeasurementsfor 4000A˚ except for small regions surrounding the emission
linesthemselves(±1000kms−1).
narrowlinesourcesarelistedinTable5,Table6,andTable7
for the [OII]λ3727, Hβ, and Hα regions measurements,
respectively. The emission line classifications are provided For sources with broad Hβ, we use the fitting procedure
described in detail in Trakhtenbrot & Netzer (2012, see
inTable8.Forbroadlinesources, thepropertiesarelistedin
BASS-I 7
Appendix C1 therein), and here we provide only a brief de-
scriptionofthekeyspectralcomponents. TheAGNspectrum For sources with broad Hα lines we used the prescription
isfirstfittedwithalinear(pseudo-)continuum,basedontwo ofGreene&Ho(2005b):
narrow (±10A˚) continuum bands, typically around 4440A˚
(or 4720A˚) and 5110A˚. Next, a broadened and shifted iron M (Hα)=1.3×106(cid:18) LHα (cid:19)0.57(cid:20)FWHM(Hα)(cid:21)2.06 M ,
emission template (Boroson & Green 1992) is fitted to, and BH 1042ergs−1 103kms−1 (cid:12)
subtracted from, the continuum-free spectrum. Then, we fit (3)
the remaining emission lines with a set of Gaussian profiles. where LHα is the integrated luminosity of the broad compo-
In particular, the narrow components of Hβ, [OIII]λ4959 nent of the Hα line, determined from the best-fitting model.
and [OIII]λ5007 are fitted with a single Gaussian profile, Thisprescriptionisthereforemostlyunaffectedbyhostlight.
whilethebroadcomponentsofHeIIandHβ aredescribedby Since the Hα-related prescription (Eq. 3) is based on a sec-
twoGaussiancomponents(each). AsdescribedinTrakhten- ondary calibration of a RBLR−L(Hα) relation, it carries
brot & Netzer (2012), the widths of the narrow components somewhatlargersystematicuncertainties(comparedwiththe
are tied among different emission lines, primarily to allow a Hβ-based one). However, it can be applied to Seyfert 1.9
robust decomposition of the narrow and broad components AGN without broad Hβ lines and it may perform better for
thatmakeuptheHβ emissionlineprofile. TheFWHMofthe sources that have high levels of stellar contamination and/or
broad Hβ line is measured from the (reconstructed) best-fit extinction. Asummaryoftheresultsofthefittingisprovided
modelofthebroadcomponent. in Fig. 4. We found about a quarter of Seyfert 1.9 (27%,
31/116) have weak broad Hα lines (EW<50A˚; see general
ForsourceswithbroadHα,weuseafittingprocedurethat discussion of Seyfert sub-classes in Section 4.2). More de-
involves several progressively complicated steps, depending tailsontheseobjectsaregivenintheAppendix.
onthecomplexityoftheemissionlines. Westartwithallow- For 19 high-redshift sources (z ∼ 1−3.3), the available
ing two Gaussian components for the Hα emission lines: a opticalspectraincludeeithertheMgIIλ2798orCIVλ1549
narrowcomponent(withFWHM<1000kms−1)andabroad broad emission lines. The emission complexes around these
component (FWHM > 1000kms−1), both with the wave- two lines were fitted using dedicated procedures, described
length centered at the Hα line. A visual inspection is made in detail in Trakhtenbrot & Netzer (2012, see Appendices
(MK,BT,KO,andIL)todeterminewhetheramorecomplex C2 and C3 therein). These take into account the (blended)
fitisrequired,thistimeusingmultipleGaussiansthatarealso emission features from iron and HeIIλ1640 transitions (in
allowed to be shifted. If the fit quality is still poor, we use the case of MgII and CIV, respectively). For both broad
thewidthofthe[OIII]line(fromtheHβ complexfittingpro- lines,eachofthedoubletfeaturesismodeledwithtwobroad
cedure)asanadditionalconstraintonthenarrowcomponents Gaussians. We assume no narrow-line contribution to these
intheHα spectralregion. Examplesofemissionlinefitsare transitions (see Trakhtenbrot & Netzer 2012, and references
givenintheAppendix. therein).
Weusedthebest-fitmodelsofthebroademissionlines,to-
3.3. BroadLineBlackHoleMassMeasurements gether with the adjacent continuum luminosities, to estimate
ForsourceswithbroadBalmerlines,weestimatedtheblack MBH in these 19 high-redshift sources. For the MgII line,
we used the prescription presented by Trakhtenbrot & Net-
hole masses (M ) through virial, “single-epoch” prescrip-
BH zer (2012), which is calibrated against Hβ-based mass esti-
tions, which are in turn based on the R −L relation ob-
BLR matesusingalargersampleofSDSSquasarsforwhichboth
tained through reverberation mapping of low-redshift AGN
lines are available. An identical prescription was also inde-
(e.g.,Kaspietal.2000;Bentzetal.2006).Thevirialmasses-
pendently derived by Shen et al. (2011). For the CIV line,
timatorsweusedforbroadHβ areknowntosufferfromsys-
weusedtheprescriptionpresentedbyVestergaard&Peterson
tematic uncertainties of about 0.3 dex (see, e.g., Shen 2013;
Peterson2014,andreferencestherein). (2006). WenotethatCIV-basedestimatesofMBH areknown
tobeconsiderablylessreliable(e.g.,Denney2012)thanthose
For sources with broad Hβ we used the same prescription
basedonlower-ionizationtransitions, perhapsduetosignifi-
used in Trakhtenbrot & Netzer (2012), which uses the con-
cantcontributionfromnon-virializedBLRgasmotiontothe
tinuum and line emission parameters for virial estimates of
emissionlineprofile(seedetaileddiscussioninTrakhtenbrot
M :
BH &Netzer2012,andreferencestherein). Wethereforeadvise
(cid:18) L (cid:19)0.65(cid:20)FWHM(Hβ)(cid:21)2 thattheCIV-baseddeterminationsofMBHprovidedheremay
MBH(Hβ)=1.05×108 10465e1r0g0s−1 103kms−1 M(cid:12),carrylargeuncertaintiesand, possibly, systematicbiases. At
such high redshifts, however, they provide the only estimate
(2)
of M , in lieu of NIR spectroscopy of the other emission
where L is the the monochromatic luminosity at rest- BH
5100 lines.
frame 5100A˚, λL (5100A˚), measured from the best-fit
λ Thespectralandderivedparametersofthe19high-redshift
model of the Hβ region. As mentioned above, FWHM(Hβ) sources are listed in Table 10. We finally note that the Swift
ismeasuredfromtheentire(best-fit)broadprofile. Although
BAT sample of AGN probably includes several other high-
the fitting procedure is executed automatically for the large
redshift(andthereforehigh-luminosity)sources,forwhichan
data-set studied here, we note that we visually inspected all
opticalspectrumisnotavailablewithinthelargeopticalsur-
theHβ fittingresults(includingmorethanonespectrumper
veys we use, and/or the effects of beaming are not yet well
source), and applied minor manual adjustments to provide
understood. Weplantoaddressthispopulationinaseparate
satisfactory fits to the data. We also stress that we did not
publication.
apply the Hβ fitting code to spectra with poor absolute flux
calibration (i.e., those from the6DF survey). A summary of
3.4. BolometricLuminosity
thesefitsisfoundinFig.3.
8 Kossetal.
withAGNclassificationbasedonthenarrowandbroadlines,
Hβ 350 and then compare it with the classification of un-obscured
0.5 d sources based on X-ray data (i.e., using the column density
a
bro 300 NH; Section 4.2). Next, we provide optical emission line
o classifications for all the AGN in the survey (Section 4.3).
0.4 N 250 WethencompareourdemographicsofBASSX-rayselected
N AGN to SDSS-selected AGN (Section 4.4). We also present
n G
Fractio00..23 Flag 1 ag 2 n lines a issues 125000 Total A ttv(hiSaeeersic,edtatiiysontndorif4abuc.u6cnt)iruo.esntuisoanloAfraGbtleNascw(kSehechotalievoenmi4da.se5sn)et.sifi,Feibndoalilonlymt,hewitsreilcadrilgsuecmusisunsrovtsheiye-
Fl o at
si D 100
ed mis ve 4.1. RedshiftDistribution
0.1 Beam No e ad fit No wa 50 enWtireebSewgiifntbByAsThoAwGinNgsaapmloptleo,futhsienXg-oruayr nluemwinreodsisthieifstimntehae-
B
surementsorthosefromNEDwhenthespectraarenotavail-
0.0 0
able(Fig.5).Wealsoshowseveralother,deepX-raysurveys,
FIG.3.—SummaryofbroadlineHβblackholemassmeasurementsusing forcomparison.Themajority(≈90%)ofBAT-detectedAGN
fittingproceduredescribedbyTrakhtenbrot&Netzer(2012)whichincludes arenearby(z<0.2). TheirX-rayluminositiesaresimilarto
fittingFeIIlines.For35%(225/641),wehaveameasurementofblackhole AGN found in deeper surveys because of the larger survey
massusingbroadHβlines.
area. Our survey finds 46 new redshifts for sources with-
“Flag1”representsanexcellentfitbasedonvisualinspection.“Flag2”
out measurement in NED. This leads to a redshift complete-
spectrahaveagoodfitbasedonvisualinspection.Theremainingcategories
(dashedhistograms)havefeaturesthatpreventedmeasurements.“Beamed ness of 96% (803/836) for the 70-month BAT AGN catalog.
AGN”aresourceswhichareknowntobebeamedandlackemissionlines. Thenewlymeasuredsourcesareatsimilarredshifts(median
“Noemissionlines”indicatesthegalaxyhasahighqualityspectrabutno z=0.049) as the sources in the rest of the sample (median
Balmerlinesaredetected.“Nowave”indicatessourcestypicallyhigh
z=0.038). A summary of the spectroscopic coverage is in
redshiftwhichlackcoverageofHβ.Finally,inasmallfractionthedata
qualitywasloworaverypoorfitwasobtained. Fig. 6.
OnlythreesourceswithredshiftsmeasuredinBASSshow
significant differences with those in NED. QSO B0347-121
250
is listed at z=0.18 in NED; however, our measurements of
α
H the6DFspectrumclearlyshowemissionlinesatz=0.032,in
d
a agreementwiththeredshifttabulatedinthe6DFcatalog.ESO
0.3 g 2 bro 200 509-IG066NED02islistedinNEDasz=0.0446;however,
a o ourmeasurementsofthe6DFspectrumclearlyshowemission
Fl N s
ue N linesatz=0.034, againinagreementwiththe6DFcatalog.
Fraction0.2 n lines Data iss wave broad 110500 Total AG 1lmiRneeXnstSsa,rJae0n9cd0lei9an1ra5lyg.6rre+ee0dm3sh5ei4nf5ttew3diitstohlitzsht=eedS3aD.s2S8zS=bcaa3ste.a2dl0ooginnmoNeuEarsDmu,reebamustuetrnhete-.
0.1 Flag 1 Beamed o emissio Bad fit No Weak 50
N
0 0
FIG.4.—SummaryofbroadlineHαblackholemassmeasurements. For
38%(242/641),wehaveameasurementofblackholemassusingbroadHα
lines.CategoriesareasinFig.3.
WeestimatedthebolometricluminosityoftheAGNinour
sample (L ) from the observed X-ray luminosity measured
bol
by the Swift BAT survey in the energy range 14–195keV.
First,wedividethe14–195keVluminosityby2.67toconvert
to the intrinsic 2–10keV luminosity, following Rigby et al.
(2009) which is based on scaling the Marconi et al. (2004)
templates to higher X-ray energies. We then used the me-
dian bolometric correction from Vasudevan et al. (2009) of
theBATsamplewhichresultedinafactorof8betweenL
bol
andL . Moreadvancedluminosity-dependentbolo-
14−195keV
metriccorrectionswillbeexaminedinfuturestudies.
4. RESULTS
In this Section we present the X-ray luminosity using our
new measurements of redshifts (Section 4.1). We proceed
BASS-I 9
1049
BAT AGN
1048 BAT AGN, beamed
Stripe 82, Chandra
COSMOS Legacy
1047
] ChaMP
1
−
CDF-S
s
·1046
g
r
e
[ 1045
)
V
e
k
01044
1
−
2
L 1043
(
g
o
l 1042
1041
1040
0.01 0.02 0.04 0.1 0.2 0.4 1 2 4
Redshift
FIG.5.—DistributionoftherestframehardX-rayluminositybasedonthe14-195keVemissionoftheBATAGN.Weusedaratioof2.67(Rigbyetal.2009)
toestimatethe2–10keVluminosityfromthe14–195keVluminosity. WehaveincludedotherdeeperX-raysurveysforcomparison. ForotherX-raysurveys
wehaveassumedΓ=1.5toestimatetheintrinsicluminosityforobscuredandunobscuredX-raysources.TheBATAGNredshiftaremeasuredfromBASSusing
narrowemissionlines,orNEDwhennospectraareavailable.ThereddashedlineshowsthefluxlimitofBATover90%ofthesky(1.34×10−11ergcm−2s−1).
TheunbeamedAGNintheBASSsampletendtospanthemoderatetohighluminosityendoftheX-rayluminosityfunction(XLF)atallredshifts.Samplesfrom
deeperpublishedsurveys,suchastheChandraDeepFieldSouth(CDF-S),tendtosamplealowerluminosityrangeoftheX-rayluminosityfunction.
100
BAT coverage
400 BASS sample
80
of sources300 T sources 60
er 200 BA
mb of 40
u %
N
100 20
0 0
0-0.05 0.05-0.1 0.1-0.2 0.2-0.5 0.5-1 > 1 no z 0-0.05 0.05-0.1 0.1-0.2 0.2-0.5 0.5-1 > 1 no z
Redshift from NED Redshift from NED
FIG.6.—SummaryofspectroscopiccoveragewithredshiftfortheBASSsample. Left: numberofsourceswithspectra(red)comparedtothenumberof
AGNintheBATcatalog(blue)atdifferentredshiftintervalsbasedonNED.TherightpanelshowsthepercentageofBATAGNcoveredbytheBASSsamplein
redshiftintervals.Themajorityofthespectraarelowredshift(z<0.05),consistentwiththeBATsample.Thespectroscopiccompletenessis75%butfallswith
increasingredshiftbecauseoftheincreasingfractionoffaintsourcesandbeamedsources.
10 Kossetal.
4.2. NarrowandBroadLineClassification
WefirstclassifytheBATAGNdependingonthepresence 0.4 y 2 250
andstrengthofbroademissionlines(e.g.,Osterbrock1981). S
ASeyfert1.9classificationisasourcewithanarrowHβ line
andbroadHα line. Weusethequantitativeclassificationsfor 200
0.3
Seyfert sub-classes (1, 1.2, 1.5, and 1.8) based on Winkler
N
(1992)usingthetotalfluxof[OIII]andHβ. Asummaryof n G
thqhauelafrrteoesfrutSlhteseyofsfeortuthri1cse.2cslaaansrsedifiS1c.e5ay.tfieoArntsc2manoarlblSefrefayocfuteinrotdn1ian.9reF,iatgrnu.de7.aSbAeoybufoeturatt Fractio0.2 1.5 Sy 1.9 ave 150Total A
1(7%)andonlytwoareSeyfert1.8sources. 2 Sy o w 100
ScaytWa1le.o9gc,oaomnfdApaSGryeN2o()uVrteoSrotehnye-fCemretotttsyytp&reescVe(eSnryto1n13,2tSh0y1e01d).i.2ti,OoSnnylVy1ea.r5om,nSi-nyCo1erti.tt8yy, 0.1 Sy 1 Sy1. Sy 1.8 Weak lines Beamed N oor fit 50
P
(36%,230/641)oftheBASSsampleisclassifiedinthiscata-
0 0
logbySeyferttype. Usingthissubsampleof230wefindthat
themajority,89%(206/230),agreewiththeSeyferttypeclas- FIG.7.—DichotomyofBATAGNdependingonthepresenceandstrength
sification with the Veron-Cetty catalog. These include 77% ofbroademissionlines. For84%ofspectra(539/641),wehavemeasure-
mentsofSeyferttypes.ASeyfert1.9classificationisasourcewithanarrow
(177/230)whichshowexacttypeagreementorarelistedasa
Hβ lineandbroadHα line. Theremainingcategories(dashedhistograms)
unspecifiedSy1intheVeronCettycatalogandfoundtobeSy havefeaturesthatpreventedmeasurements. “Weaklines”referstoobjects
1,Sy1.2,Sy1.5,orSy1.9inBASS.Another13%(29/230) withoutthepresenceofanyBalmeremissionlinesinthespectradespitehigh
are Sy 1, but are listed as Sy 1.2 or Sy 1.5 and vice versa in qualityspectra. WeusethequantitativeclassificationsforSeyferttypes(1,
1.2,1.5,1.8)basedonWinkler(1992)usingthetotalfluxof[OIII]andHβ.
BASS.
The remaining 10% (24/230) show disagreement among catalog are now classified as Sy 1.9 because of broad lines
Seyfert type between BASS and Veron-Cetty. The majority detected in Hα for the first time. Finally, 8 sources show a
ofthesearelistedasSy1.9inoursamplebutarefoundtobe different Seyfert type possibly due to variability which will
Sy2inVeron-Cetty67%(16/24)mostlikelybecauseourof befurtherstudiedinfuturepublications.
higherqualityspectra. TherearenoexamplesofSy1.9inthe
Veron-CettycatalogwhicharefoundtobeSy2inourcatalog. In Figure 8 we present the fraction of sources with broad
Hα and/or Hβ lines, plotted against X-ray luminosity. For
Another six sources are Sy 1 unspecified in Veron-Cetty, both the 14–195keV and 2–10keV luminosities we find a
butSy2inourcatalog. ForPKS0326-288, theVeron-Cetty generalincreaseintype1fractionwithincreasingluminosity,
reference (Mahony et al. 2011) lists the source as a narrow as has been found in past studies using broad Hβ (see e.g.,
line source in agreement with our classification. MCG +02- Merloni et al. 2014, and references therein). We find that
21-013 has no references in the Veron-Cetty catalog for the AGNwithbroadHα linesareconsistentlymorecommon,by
Seyferttype,butNEDlistsbothaSy1andSy2inagreement about10–20%,thanAGNwithHβ lines,acrossawiderange
with our classification. NGC 4992 has no references in the ofX-rayluminosity.
Veron-Cetty catalog for the Seyfert type, but is classified as
a Sy 2 in a recent paper by Smith et al. (2014) in agreement Finally, in Fig. 9 we plot the FWHM of Hα as a function
with our classification. A recent paper on MCG+04-48-002 of the column density derived from the X-rays (N ). We
H
(Koss et al. 2016b) lists it as a Sy 2 in agreement with our note that roughly half (57%, 128/223) of Seyfert 1-1.8
classification while it has no references in the Veron-Cetty broad-line AGN with column density measurements have
catalogfortheSeyferttype. NGC5231islistedasaSy2to onlyupperlimitsonN ,at1020cm−2correspondingtobeing
H
match our classification in recent work (Parisi et al. 2012). unobscured.
Finally, 2MASX J10084862-0954510 is shown to be a Sy 1
inBaueretal.(2000)withbroadBalmerlineswhichisvery The FWHM of the emission lines show broad agreement
differentfromourspectraandmaybeacaseofvariability. with the X-ray obscuration (∼94%), such that Seyfert sub-
types1,1.2,1.5,and1.8haveN <1021.9cm−2,andSeyfert
H
Finally, two sources are listed as Sy 1.0 in Veron-Cetty, 2,haveN >1021.9cm−2. Seyfert1.9,however,showarange
H
but are listed as Sy 1.9 in the BASS catalog. The reference
ofcolumndensities.
for ESO 198-024 as a Sy 1.0 in Veron-Cetty is based on
imagingvariability(Winkleretal.1992)intheopticalrather
Additionally, a small fraction of Seyfert 2 sources (6%,
than spectroscopy and could be consistent with our Sy 1.9
14/221), have X-ray obscuration below N = 1021.9 cm−2.
classification. Finally, the reference in Veron-Cetty for a Sy H
We note however that Seyfert 1.9 sources, which have evi-
1.0 classification (Guainazzi et al. 2000) lists the source as
denceofabroadlineinHα, butnotHβ, spanthefullrange
a Sy 1.9 which is the same as our classification though the
ofcolumndensitiesfromunobscuredtoCompton-thick(i.e.,
authorsmentionthesourcemayhavechangedfromanarrow
N <1024cm−2).
lineAGNtoaSy1.9. H
In summary, we find broad agreement (89%) with past
studies of Seyfert type classification from the Veron-Cetty
catalog. Themajordifferenceisthat16sourcesintheBASS