J/A+A/541/A77 Kohonen-selected unusual SDSS quasars (Meusinger+, 2012)
Unusual quasars from the Sloan Digital Sky Survey selected
by means of Kohonen Self-Organizing Maps.
Meusinger H., Schalldach P., Scholz R.-D., in der Au A., Newholm M.,
de Hoon M., Kaminsky B.
<Astron. Astrophys. 541, A77 (2012)>
=2012A&A...541A..77M 2012A&A...541A..77M
ADC_Keywords: Active gal. nuclei ; Spectral types ; QSOs ; Redshifts
Keywords: galaxies: active - quasars: general - quasars: absorption lines -
quasars: emission lines - black hole physics
Abstract:
Large spectroscopic surveys have discovered very peculiar and hitherto
unknown types of active galactic nuclei (AGN). Such rare objects may
hold clues to the accretion history of the supermassive black holes at
the centres of galaxies.
We aim to create a sizeable sample of unusual quasars from the
unprecedented spectroscopic database of the Sloan Digital Sky Survey
(SDSS).
Description:
We present a catalogue of 1005 quasars with unusual spectra in the
redshift interval from 0.6 to 4.3. The quasars were selected from the
Sloan Digital Sky Survey Data Release 7 (Abazajan+,
2009ApJS..182..543A 2009ApJS..182..543A) by means of Kohonen self-organising maps. The
spectra are dominated by either broad absorption lines (42%), unusual
red continua (27%), weak emission lines (18%), or conspicuously strong
optical and/or UV iron emission (11%). This large sample provides a
useful resource for both studying properties and relations of/between
different types of unusual quasars and selecting particularly
interesting objects, even though the compilation is not aimed at
completeness in a quantifiable sense. The spectra are grouped into
seven types. The catalogue contains the redshift, the absolute
magnitude, the spectral type, the radio loudness parameter, a
peculiarity index, and some comments on peculiar spectral features.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 105 1005 Unusual quasar catalogue
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
http://www.sdss.org : SDSS Home Page
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1005] Running number
6- 23 A18 --- SDSS SDSS J2000 equatorial coordinates
(HHMMSS.ss+DDMMSS.s)
25 I1 --- fc [0/2] QCDR7 catalogue flag (1)
26- 32 F7.3 --- z ?=-9.999 Redshift from present study
34 I1 --- q_z [0/3] Redshift uncertainty flag, 0=certain (2)
36- 40 F5.2 mag i0mag i magnitude, corrected for galactic
extinction (3)
42- 47 F6.2 mag iMAG ?=-99.99 Absolute i magnitude (4)
49 I1 mag fr [0/1] FIRST detection flag, 0=detection (5)
51- 57 F7.2 mJy F1.4 ?=-99.99 FIRST 1.4GHz peak flux
59- 64 F6.2 --- Ri ?=-99.99 Radio loudness parameter (6)
66- 69 I4 --- chi2 ?=-999 Peculiarity index
71 I1 --- T1 [0/7] Type of highest significance (7)
73 I1 --- T2 [0/7] Type of median significance (7)
75 I1 --- T3 [0/7] Type of lowest significance (7)
77-105 A29 --- Com Comments (8)
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Note (1): QCDR7 catalogue flag as follows:
0 = not in QCDR7 (Schneider+ 2010AJ....139.2360S 2010AJ....139.2360S, Cat. VII/260)
1 = in QCDR7, deviation in redshift <10%
2 = in QCDR7, deviation in redshift >10%
Note (2): Redshift uncertainty flag as follows:
0 = certain
1 = likely, but not certain
2 = lack of certainly identifiable redshift indicators
3 = low signal-to-noise
Note (3): Galactic foreground extinction from the "Galactic Dust Extinction
Service" of the NASA/IPAC Infrared Science Archive
Note (4): following Kennefick and Bursick (2008AJ....136.1799K 2008AJ....136.1799K) with
alphaν=-0.5.
Note (5): 0/1 for detection/nondetection
Note (6): following Ivezic et al. (2002AJ...124.2364I)
Note (7): Type of significance flag as follows:
1 = unusual BAL quasars (mostly LoBAL quasars)
2 = quasars with strong but common BAL structures (mostly HiBALs)
3 = quasars where the whole continuum is significantly redder than
the SDSS composite
4 = quasars with strong reddening in the ultraviolet
5 = weak emission line quasars
6 = strong iron emitters
7 = miscellaneous
0 = no type (only for T2 and T3)
Note (8): Used abbreviations:
abs = absorption
ao = associated absorption
bel = blueshifted emission line
bq = (very) blue quasar
em = emission
dlas = damped Lyman alpha absorption system
fg = foreground
lst = longward-of-systemic trough
mnt = many narrow troughs
myst? = related to the two mysterious objects from Hall et al.
(2002ApJS..141..267H 2002ApJS..141..267H)
nlq = narrow-line quasar
nt = narrow troughs
ot = overlapping troughs
sdvdpc = spatially distinct velocity-dependent partial covering
see 0810(H02) = see object SDSS J081024.75+480615.5 in Hall et al.
(2002ApJS..141..267H 2002ApJS..141..267H)
uc = unusual continuum
ulp = unusual line profile
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Acknowledgements:
Helmut Meusinger, meus(at)tls-tautenburg.de
(End) Helmut Meusinger [TLS, Germany], Patricia Vannier [CDS] 01-Mar-2012