J/MNRAS/543/3649 Catalogue of type 2 AGN in 6dF galaxy survey (Suresh+, 2025)
A catalogue of Type 2 active galactic nuclei in the 6dF galaxy survey.
Suresh S., Hon W.J., Webster R.L., Wolf C., Onken C.A.
<Mon. Not. R. Astron. Soc. 543, 3649-3663 (2025)>
=2025MNRAS.543.3649S 2025MNRAS.543.3649S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, Seyfert ; Line Profiles ;
Galaxies, spectra ; Spectral types
Keywords: techniques: spectroscopic - catalogues - galaxies: active -
galaxies: nuclei - (galaxies:) quasars: emission lines -
galaxies: Seyfert
Abstract:
Active galactic nuclei (AGNs) are the compact, energetic central
regions of galaxies, powered by supermassive black holes that accrete
surrounding gas and dust. Their optical spectra can be identified by
strong emission-line signatures (broad and/or narrow lines). Those
showing only narrow lines are classified as "Type 2" AGN. Extensive
surveys like SDSS cover AGN in the Northern Sky, but the equivalent
coverage in the Southern Sky remains limited. We address this by
presenting a new catalogue of Type 2 AGN from the 6dF Galaxy Survey
(6dFGS), which has 136304 spectra covering ∼17000deg2, mainly of
low-redshift galaxies. We use a median absolute deviation cut on the
continuum-fitted spectrum to select emission line galaxies. AGN were
identified by fitting the 6dFGS spectra with a modified Python QSO
fitting tool (PyQSOFit). All selected spectra were visually inspected
and corrected for fitting errors where necessary. 10492 narrow
emission line galaxies were identified in 6dFGS, including ∼5000 Type
2 AGN classified from Baldwin-Phillips-Terlevich (BPT) diagram. They
have a median redshift of z∼0.032 and a median [OIII] luminosity of
log(L[OIII]/(erg/s))~=40.04.
Description:
This catalogue contains 10503 narrow emission-line galaxies identified
in the 6dF Galaxy Survey (6dFGS), including 5002 Type 2 AGN classified
with the Baldwin Phillips Terlevich (BPT) diagram. Spectra were
analysed with PyQSOFit after applying a Median Absolute Deviation
(MAD) cut, followed by visual inspection.
The table provides redshift, emission-line measurements, derived
fluxes and luminosities, photometric data from SkyMapper and 2MASS,
and classification flags.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
t2agn.dat 488 10492 Catalogue of type 2 AGN in 6dF galaxy survey
--------------------------------------------------------------------------------
See also:
VII/259 : 6dF Galaxy Survey final redshift release (Jones+, 2009)
II/379 : SkyMapper Southern Sky Survey. DR4 (Onken+, 2024)
Byte-by-byte Description of file: t2agn.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- SpecID 6dFGS Spec ID (SPEC_ID)
8- 27 A20 --- DuplID Duplicate Spec ID (if any),
separated by ';' (DUPLICATE_ID)
29- 40 F12.8 deg RAdeg Right Ascension (J2000) (RA)
42- 53 F12.8 deg DEdeg Declination (J2000) (DEC)
55- 69 A15 --- 6dFGS 6dFGS unique source identifier
(gHHMMSSs+DDMMSS) (6dFGS_NAME)
71- 73 I3 --- ProgID ? 6dFGS program id (PROG_ID) (1)
75 I1 --- Qual [3/4] Quality flag provided by 6dFGS
(QUALITY)
77- 85 F9.6 --- z Redshift (Z)
87- 92 F6.2 km/s FWHMHb FWHM of Hbeta (FWHM_HBETA)
94- 99 F6.2 km/s e_FWHMHb FWHM of Hbeta error (FWHMHBETAERR)
101-107 F7.2 0.1nm PeakHb Peak wavelength of Hbeta (PEAK_HBETA)
109-113 F5.2 0.1nm e_PeakHb Peak wavelength of Hbeta error
(PEAKHBETAERR)
115-120 F6.2 ct FluxHb Flux of Hbeta (in counts) (FLUX_HBETA)
122-125 F4.2 --- e_FluxHb Flux error of Hbeta (FLUXHBETAERR)
127-133 F7.2 km/s FWHMOIII FWHM of [OIII] (FWHM_OIII)
135-140 F6.2 km/s e_FWHMOIII FWHM of [OIII] error (FWHMOIIIERR)
142-148 F7.2 0.1nm PeakOIII Peak wavelength of [OIII] (PEAK_OIII)
150-153 F4.2 0.1nm e_PeakOIII Peak wavelength of [OIII] error
(PEAKOIIIERR)
155-160 F6.2 ct FluxOIII Flux of [OIII] (in counts) (FLUX_OIII)
162-166 F5.2 --- e_FluxOIII Flux error of [OIII] (FLUXOIIIERR)
168-173 F6.2 km/s FWHMHa FWHM of Halpha (FWHM_HALPHA)
175-180 F6.2 km/s e_FWHMHa FWHM of Halpha error (FWHMHALPHAERR)
182-188 F7.2 0.1nm PeakHa Peak wavelength of Halpha (PEAK_HALPHA)
190-193 F4.2 0.1nm e_PeakHa Peak wavelength of Halpha error
(PEAKHALPHAERR)
195-200 F6.2 ct FluxHa Flux of Halpha (in counts) (FLUX_HALPHA)
202-206 F5.2 --- e_FluxHa Flux error of Halpha (FLUXHALPHAERR)
208-213 F6.2 km/s FWHMNII FWHM of [NII] (FWHM_NII)
215-220 F6.2 km/s e_FWHMNII FWHM of [NII] error (FWHMNIIERR)
222-228 F7.2 0.1nm PeakNII Peak wavelength of [NII] (PEAK_NII)
230-233 F4.2 0.1nm e_PeakNII Peak wavelength of [NII] error
(PEAKNIIERR)
235-239 F5.2 ct FluxNII Flux of [NII] (in counts) (FLUX_NII)
241-245 F5.2 --- e_FluxNII Flux error of [NII] (FLUXNIIERR)
247-251 F5.2 --- log(OIII/Hb) Log of flux ratio [OIII]/Hbeta
(LOGOIIIHB)
253-257 F5.2 --- log(NII/Ha) Log of flux ratio [NII]/Halpha
(LOGNIIHA)
259-263 A5 --- BPT BPT classification of the source
(BPT) (2)
265 I1 --- Flag [0/2] Contamination flag (FLAG) (3)
267-276 I10 --- SMSS ? SkyMapper Southern Sky Survey (SMSS)
object ID (SMSS_ID)
278-282 F5.2 arcsec SMSSDist ? Distance to closest SMSS source
(SMSS_DIST)
284-288 F5.2 mag rmag ? SMSS r-band photometry (RMAG)
290-293 F4.2 mag e_rmag ? SMSS r-band photometry error (RMAG_ERR)
295-299 F5.2 mag gmag ? SMSS g-band photometry (GMAG)
301-304 F4.2 mag e_gmag ? SMSS g-band photometry error (GMAG_ERR)
306-309 F4.2 mag E(B-V) ? E(B-V) reddening (EBMV)
311-318 E8.2 mW/m2 Fluxr SMSS r-band photometry flux (FLUX_R)
320-327 E8.2 mW/m2 Fluxg SMSS g-band photometry flux (FLUX_G)
329-336 E8.2 mW/m2 CFluxHb ? Calibrated flux estimate of Hbeta
(CFLUX_HB)
338-345 E8.2 mW/m2 e_CFluxHb ? Calibrated flux error of Hbeta
(CFLUXHBERR)
347-354 E8.2 mW/m2 DeFluxHb ? Dereddened flux estimate of Hbeta
(DEFLUX_HB)
356-363 E8.2 mW/m2 CFluxOIII ? Calibrated flux estimate of [OIII]
(CFLUX_OIII)
365-372 E8.2 mW/m2 e_CFluxOIII ? Calibrated flux error of [OIII]
(CFLUXOIIIERR)
374-381 E8.2 mW/m2 DeFluxOIII ? Dereddened flux estimate of [OIII]
(DEFLUX_OIII)
383-387 F5.2 [10-7W] logLHb ? Log luminosity of Hbeta (LOGL_HB)
389-392 F4.2 --- e_logLHb ? Error in log luminosity of Hbeta
(LOGLHBERR) (4)
394-398 F5.2 [10-7W] logLOIII ? Log luminosity of [OIII] (LOGL_OIII)
400-403 F4.2 --- e_logLOIII ? Error in log luminosity of [OIII]
(LOGLOIIIERR) (4)
405 I1 --- ImgFlag [0/2]? Imaging flag (IM_FLAG) (5)
407-422 A16 --- 2MASS ? 2MASS unique source identifier
(2MASS_ID)
424-428 F5.2 mag Jmag ? 2MASS J-band magnitude (JMAG)
430-433 F4.2 mag e_Jmag ? 2MASS J-band magnitude error (JMAG_ERR)
435-439 F5.2 mag Hmag ? 2MASS H-band magnitude (HMAG)
441-444 F4.2 mag e_Hmag ? 2MASS H-band magnitude error (HMAG_ERR)
446-450 F5.2 mag Kmag ? 2MASS K-band magnitude (KMAG)
452-455 F4.2 mag e_Kmag ? 2MASS K-band magnitude error (KMAG_ERR)
457-461 F5.2 mag Jext ? 2MASS J-band extended source magnitude
(JEXT)
463-466 F4.2 mag e_Jext ? 2MASS J-band extended source magnitude
error (JEXT_ERR)
468-472 F5.2 mag Hext ? 2MASS H-band extended source magnitude
(HEXT)
474-477 F4.2 mag e_Hext ? 2MASS H-band extended source magnitude
error (HEXT_ERR)
479-483 F5.2 mag Kext ? 2MASS K-band extended source magnitude
(KEXT)
485-488 F4.2 mag e_Kext ? 2MASS K-band extended source magnitude
error (KEXT_ERR)
--------------------------------------------------------------------------------
Note (1): Program ID as provided by 6dFGS. For more details refer to
VII/259 : 6dF galaxy survey final redshift release.
Note (2): BPT classifies sources as follows:
AGN = Active galactic nuclei
AGN* = Active galactic nuclei with absence of Hbeta emission line
SF = Starforming
SF* = Starforming with absence of Hbeta emission line
COMP = Composite
COMP* = Composite with absence of Hbeta emission line
Note (3): Contamination flag as follows:
1 = contaminated by Crosstalk
2 = contaminated by Telluric line
0 = no contamination
Note (4): Log error has been converted to linear error, so it is a
dimentionless quantity.
Note (5): Imaging flag as follows:
0 = Single, calibrated source
1 = More than one object within 6.7" aperture (contaminated)
2 = Uncalibrated source
--------------------------------------------------------------------------------
Acknowledgements:
Sruthi Suresh, sruthis(at)student.unimelb.edu.au
(End) Patricia Vannier [CDS] 18-Sep-2025