J/ApJ/705/L76 AGNs with double-peaked [OIII] lines (Wang+, 2009)
Active galactic nuclei with double-peaked narrow lines: are they dual active
galactic nuclei?
Wang J.-M., Chen Y.-M., Hu C., Mao W.-M., Zhang S., Bian W.-H.
<Astrophys. J., 705, L76-L80 (2009)>
=2009ApJ...705L..76W 2009ApJ...705L..76W
ADC_Keywords: Redshifts ; Galaxies, spectra ; Active gal. nuclei
Keywords: black hole physics - galaxies: evolution
Abstract:
Double-peaked [OIII] profiles in active galactic nuclei (AGNs) may
provide evidence for the existence of dual AGNs, but a good diagnostic
for selecting them is currently lacking. Starting from ∼7000 active
galaxies in Sloan Digital Sky Survey DR7, we assemble a sample of 87
type 2 AGNs with double-peaked [OIII] profiles. The nuclear
obscuration in the type 2 AGNs allows us to determine redshifts of
host galaxies through stellar absorption lines. We typically find that
one peak is redshifted and another is blueshifted relative to the host
galaxy. We find a strong correlation between the ratios of the shifts
and the double peak fluxes. The correlation can be naturally explained
by the Keplerian relation predicted by models of co-rotating dual
AGNs. The current sample statistically favors that most of the [OIII]
double-peaked sources are dual AGNs and disfavors other explanations,
such as rotating disk and outflows. These dual AGNs have a separation
distance at ∼1kpc scale, showing an intermediate phase of merging
systems. The appearance of dual AGNs is about ∼10-2, impacting on
the current observational deficit of binary supermassive black holes
with a probability of ∼10-4 (Boroson & Lauer, 2009Natur.458...53B 2009Natur.458...53B).
Description:
We start from the galaxy sample of SDSS DR7 and select active galaxies
based on the widely used BPT diagram. Using the measured fluxes of
narrow emission lines from the MPA/JHU catalog, we separate type 2
AGNs from other sources according to their line ratios. We select
those objects with SDSS r-band magnitude r<17.7, redshift z≤0.15, and
equivalent width of [OIII]5007>5. In total, 6780 type 2 AGNs follow
from this criterion. Finally, we are left with 87 sources having a
flux ratio in the range of [0.3,3], 44 of which have high enough
signal-to-noise ratio of the spectra to see similar double-peaked
structures in other lines (e.g., [OIII]4959, Hβ, Hα, [NII],
[SII]).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 87 The sample of type 2 AGNs
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/A+A/534/A110 : Type-2 AGN from XMM-COSMOS bolometric output (Lusso+, 2011)
J/A+A/510/A56 : zCOSMOS type-2 AGN (Bongiorno, 2010)
J/MNRAS/399/1206 : SWIRE/SDSS quasars. II. Type 2 AGN (Hatziminaoglou+, 2009)
J/AJ/130/381 : Blueshifted [O III] emission (Boroson+, 2005)
J/ApJS/143/257 : AGN emission line properties (Kuraszkiewicz+, 2002)
J/ApJ/549/155 : [OIII] emission in a sample of AGNs (Nagao+, 2001)
http://www.mpa-garching.mpg.de/SDSS/DR7/ : MPA-JHU DR7 spectrum measurements
http://www.sdss.org/ : SDSS home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 19 A14 --- Name AGN SDSS identification (JHHMMSS+DDMMSS)
21- 27 F7.5 --- z Spectroscopic redshift
29- 34 E6.1 --- e_z Uncertainty in z
36- 39 F4.2 0.1nm Del1 The [OIII] doppler blue shift in Angstroms
41- 44 F4.2 0.1nm e_Del1 Uncertainty in Del1 in Angstroms
46- 49 F4.2 0.1nm Del2 The [OIII] doppler red shift in Angstroms
51- 54 F4.2 0.1nm e_Del2 Uncertainty in Del2 in Angstroms
56- 59 I4 10-20W/m2 FOIII1 The red [OIII] flux in 10-17erg/s/cm2
61- 62 I2 10-20W/m2 e_FOIII1 Uncertainty in FOIII1 in 10-17erg/s/cm2
64- 67 I4 10-20W/m2 FOIII2 The blue [OIII] flux in 10-17erg/s/cm2
69- 71 I3 10-20W/m2 e_FOIII2 Uncertainty in FOIII2 in 10-17erg/s/cm2
73- 76 F4.2 --- D ? Separation of two components in the BPT
diagram (Baldwin, Phillips & Terlevich,
1981PASP...93....5B 1981PASP...93....5B)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Dec-2011