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MISCLASSIFIED TYPE 1 AGNS IN THE LOCAL UNIVERSE
MISCLASSIFIED TYPE 1 AGNS IN THE LOCAL UNIVERSE
Journal of The Korean Astronomical Society. 2014. Sep, 47(5): 167-178
Copyright © 2014, null
  • Received : August 25, 2014
  • Accepted : September 19, 2014
  • Published : September 20, 2014
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About the Authors
Jong-Hak Woo
Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Koreawoo@astro.snu.ac.kr
Ji-Gang Kim
R&E Program, Gyeonggi Science High School for the Gifted, 68-23 Songjuk, Jangan, Suwon 440-800, Korea
Daeseong Park
Department of Physics and Astronomy, University of California Irvine, CA, USA
Hyun-Jin Bae
Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749, Korea
Jae-Hyuk Kim
R&E Program, Gyeonggi Science High School for the Gifted, 68-23 Songjuk, Jangan, Suwon 440-800, Korea
Seung-Eon Lee
Sang Chul Kim
Korea Astronomy and Space Science Institute, Daejeon 305-348, Korea
Hong-Jin Kwon
R&E Program, Gyeonggi Science High School for the Gifted, 68-23 Songjuk, Jangan, Suwon 440-800, Korea

Abstract
We search for misclassified type 1 AGNs among type 2 AGNs identified with emission line flux ratios, and investigate the properties of the sample. Using 4 113 local type 2 AGNs at 0.02 < z < 0.05 selected from Sloan Digital Sky Survey Data Release 7, we detected a broad component of the Hα line with a Full-Width at Half-Maximum (FWHM) ranging from 1 700 to 19 090 km s −1 for 142 objects, based on the spectral decomposition and visual inspection. The fraction of the misclassified type 1 AGNs among type 2 AGN sample is ∼3.5%, implying that a large number of missing type 1 AGN population may exist. The misclassified type 1 AGNs have relatively low luminosity with a mean broad Hα luminosity, log L = 40.50 ± 0.35 erg s −1 , while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log M BH = 6.94 ± 0.51 M . The mean Eddington ratio of the sample is log L bol /L Edd = −2.00±0.40, indicating that black hole activity is relatively weak, hence, AGN continuum is too weak to change the host galaxy color. We find that the Oiii lines show significant velocity offsets, presumably due to outflows in the narrow-line region, while the velocity offset of the narrow component of the Hα line is not prominent, consistent with the ionized gas kinematics of general type 1 AGN population.
Keywords
1. INTRODUCTION
Large-area surveys performed in various wavelengths, i.e., X-ray, optical, near-infrared, and mid-infrared, provide a large sample of active galactic nuclei (AGNs), enabling various statistical studies of actively mass ac- creting supermassive black holes. In particular, by providing the rest-frame optical and UV spectroscopic properties of more than 100 000 AGNs over a large red- shift range, the Sloan Digital Sky Survey (SDSS) has dramatically changed our understanding of AGN pop- ulation (e.g., Abazajian et al. 2009), including the local black hole activity (see Heckman & Best 2014), AGN luminosity and Eddington ratio functions from low- to high-redshift (e.g., Kelly & Shen 2013), and the con- nection of black hole activity to star formation (e.g., Netzer 2009).
However, all surveys have their selection functions, hence, it is challenging to avoid selection biases in pro- viding a complete sample of AGNs. In the case of the SDSS, the color-color diagram based on the imag- ing survey has been used for selecting potential AGN candidates as spectroscopic follow-up targets. Thus, obscured AGNs, i.e., red AGNs (e.g., Glikman et al. 2007, 2013) and X-ray-bright-optically-normal AGNs (e.g., Hornschemeier et al. 2005), can be easily missed from the survey.
In the optical spectroscopic studies, type 1 and type 2 AGNs are often classified based on the presence or ab- sence of broad-emission lines, which are usually defined having a FWHM larger than 1000 km s −1 , as initially recognized among nearby Seyfert galaxies (e.g., Seyfert 1943). However, if the broad component of the Balmer lines is relatively weak and/or the narrow component is dominant, then it is likely that type 1 AGNs can be misclassified as type 2 AGNs. In addition, if the AGN continuum is relatively weak compared to the stellar continuum, then these objects are likely to be classi- fied as galaxies rather than AGNs in the color-color diagram.
A number of statistical studies have been performed using the SDSS galaxy catalogues, e.g., the MPA- JHU value-added catalog, 1 and the KIAS value-added galaxy catalog (Choi et al. 2010), which contain the flux-limited local galaxy sample out to z ∼ 0.2, to inves- tigate the properties of type 2 AGN populations iden- tified through the emission line flux ratios (Baldwin et al. 1981; Kewley et al. 2006). It has been noticed that some type 2 AGNs show a relatively broad component in the H α line, while a broad component is often missing in the H β line, presumably due to its weak flux com- pared to the stellar continuum, suggesting that at least some fraction of type 2 AGNs identified through their emission line ratios could be genuine type 1 AGNs. A systematic search for these misclassified type 1 AGNs is yet to be performed (see, e.g., Oh et al. 2011; Bae & Woo 2014). These misclassified AGNs are interesting targets for further study since they are likely to be low luminosity AGNs since their AGN continuum is rela- tively weak. At the same time, their host galaxy prop- erties can be easily studied while the mass of the central black hole can be estimated from the broad component of H α using various single-epoch mass estimators (e.g., Woo & Urry 2002; Park et al. 2012; Bentz et al. 2013).
In this paper, we search for misclassified type 1 AGNs using a large sample of local type 2 AGNs selected from SDSS DR7, by carefully examining the presence of the broad component of the H α line. Based on the newly found type 1 AGNs, we investigate the properties of black hole activity and the kinematics of the ionized gas. Sample selection and the procedure for identifying type 1 AGNs are described in Sections 2 and 3, respec- tively. In Section 4, we present the properties of the newly found 142 type 1 AGNs and their gas proper- ties. Discussion and conclusions are presented in Sec- tion 5. Throughout the paper, we used the cosmologi- cal constants of H 0 = 70 kms −1 Mpc −1 , Ω m = 0.3, and Ω Λ = 0.7.
2. SAMPLE SELECTION
To select type 2 AGNs in the local universe, we utilized the MPA-JHU catalog, which contains 927 552 galax- ies from the SDSS DR 7 and their derived properties. We selected low-redshift galaxies (i.e., 0.02 < z < 0.05) and excluded galaxies with low stellar velocity disper- sion (i.e., below the SDSS instrumental resolution, σ < 70 km s −1 ) in order to utilize the available stellar ve- locity dispersion measurements in comparing with the gas kinematics. Among these local galaxies, we se- lected emission-line objects with signal-to-noise ratio S/N ≥ 3 for H α , H β , O I , and O III , which were used to classify AGNs in the emission line flux ratio diagram (Baldwin et al. 1981). By using the demarcation line for AGNs and star-forming galaxies, 0.73/[log O I /H α +0.59 ] +1.33 < log O III /H β or log O I /H α > −0.59 (Kewley et al. 2006), we selected 4 113 objects as the type 2 AGN sample.
3. ANALYSIS
- 3.1. Spectral Decomposition
In studying type 2 AGNs, it is of importance to decom- pose AGN emission lines from the host galaxy stellar continuum in order to properly measure the flux and width of each AGN emission line. For relatively low luminosity AGNs, the line strength of stellar absorp- tion lines is significantly large, hence the precise mea- surements of AGN emission line flux requires spectral decomposition of the stellar component, for example, using stellar population models or stellar spectral tem- plates (e.g., Park et al. 2012). In addition, for mea- suring the kinematics of the ionized gas, it is necessary to measure the systemic velocity of the target galaxy based on the stellar absorption lines. In this study, we used the penalized pixel-fitting (pPXF) method (Cap- pellari & Emsellem 2004) to obtain the best fit stellar continuum model, which is based on the 235 simple stel- lar population models (i.e., 5 different metallicities × 47 different ages) from the MILES library. First, we de-redshifted all spectra using the redshift value from SDSS. After fitting with the stellar continuum model, we refined the redshift (hence, the systemic velocity) of each object before the emission line fitting proce- dure. Then, the best-fit continuum model was sub- tracted from the SDSS spectra, leaving the pure AGN emission-line spectra. This approach is similar to a number of previous studies on the AGN emission and stellar absorption lines (e.g., Woo et al. 2010; Park et al. 2012; Woo et al. 2013). We present an example of the spectral decomposition in Figure 1 .
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Example of the spectral decomposition for SDSS J140543.16+251352.9. The SDSS spectrum (black line) is modeled with a stellar population model (red line). The residual spectrum at the bottom represents a pure AGN emission line spectrum.
- 3.2. Emission Line Fitting
We examined the SDSS spectra and continuum-subtracted spectra of all 4,113 objects in the type 2 AGN sample, in order to determine whether a broad component is present in the H α line. In this process, we identified a sample of potential type 1 AGN can- didates showing the broad H α component, based on the visual inspection. Then, we carefully examined the H α region in the rest-frame 6300–6900Å, by decom- posing the broad and narrow components of H α , and N II lines simultaneously. If the stellar continuum was poorly subtracted from the SDSS spectra due to the low S/N ratio, a straight line was adopted to represent the continuum.
Using the MPFIT routine (Markwardt 2009), we modeled each narrow emission line in the H α region, namely, H α λλ6563, N II λλ6548, 6583 doublet, and S II λλ 6716, 6731 doublet with a single Gaussian com- ponent. In addition, we added a Gaussian component with a FWHM > 1000 km s −1 , to represent the broad component of H α . The centers of each Gaussian com- ponents for narrow emission lines were fixed relative to each other at their laboratory separations, while the center of the broad H α component was set to vary in the fitting process. In the case of the line width, we used the same line dispersion value for all narrow emis- sion lines, but for the broad H α component, we used a free parameter. The line flux ratio of [N II ] λ6583 and [N II ] λ6548 is fixed at the theoretical value of 2.96.
Note that a broad residual from the incorrect sub- traction of stellar continuum or the combination of the narrow H α and N II line wings could be misinterpreted as a broad-line component. Thus, a careful examina- tion is required to avoid false detection of a broad H α component. For each object, we carefully examined and compared the raw spectrum and the best-fit model, and compared the raw spectrum and the best-fit model, and conservatively classified the target as type 1 AGNs only if the broad H α component is clearly needed for the fit. In particular, when the broad H α is relatively narrow (i.e., FWHM < ∼2000 km s −1 ), hence we do not see the wing of the broad H α blueward and redward of N II in the continuum-subtracted spectra, we removed the target from the list of the type 1 AGN candidates although the best-fit model includes a broad H α com- ponent. Thus, in our conservative classification it is possible that we may miss relatively narrow broad-line objects (e.g., narrow-line Seyfert 1 galaxies). In this process, we identified 142 AGNs, which clearly showed a broad H α component. Figure 2 presents examples of the emission line fit in the H α region for 15 AGNs in increasing magnitude of the FWHM of the broad H α component.
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Examples of the best-fit emission line models in the Hα region for 15 objects, are presented in order of increasing FWHM of the broad Hα component. Continuum-subtracted spectra (black lines) are plotted together with the best-fit models (red lines), which are composed of narrow lines (NII, Hα , and SII) and a broad Hα component. At the bottom of each panel the residual is presented (black lines). The object name and the FWHM of the broad Hα component are given in each panel.
We measured the line flux and line dispersion of each narrow emission line and the broad H α line from the best-fit model. We used the luminosity distance using the redshift information in the header of the fits file or the measured redshift from the stellar absorption lines. These two redshifts showed negligible difference in lu- minosity distance. Figure 3 presents the distributions of the widths and luminosities of the broad H α compo- nent (see Section 4.1 for details).
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Distribution of the measured FWHM (left), log L (center), log MBH (right) for 142 misclassified type 1 AGNs.
We also fit the O III line at 5007Å, to measure the velocity center and the velocity dispersion. Since the majority of the AGNs in the sample show a broad wing component in the O III line profile, we used a double Gaussian model to fit the line profile. Then, we mea- sured the flux centroid velocity and velocity dispersion of the best-fit double-Gaussian model.
- 3.3. Black HoleMass and Eddington ratio
Dynamical black hole mass estimation based on the spa- tially resolved kinematics is limited to nearby galax- ies due to the limited spatial resolution (Kormendy & Ho 2013). For broad-line AGNs, black hole mass (M BH ) can be measured with the reverberation map- ping method based on the virial assumption of the gas in the broad-line region (BLR) (Blandford & McKee 1982). Under the virial relation, black hole mass is ex- pressed as M BH = f V 2 R BLR / G , where V is the char- acteristic velocity scale of the broad-line gas, typically measured from the line dispersion of the Balmer lines, f is the virial coefficient, which depends on the mor- phology, orientation, and the kinematics of the BLR, R BLR is the size of the BLR measured from the rever- beration mapping campaign, and G is the gravitational constant.
Adopting the BLR size – luminosity relation from the recent calibration by Bentz et al. (2013),
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the virial relation can be written as follows:
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For the misclassified AGNs, we used the line width and luminosity of the broad H α for estimating black hole masses. Adopting the calibration between the widths of H β and H α (i.e., FWHM –FWHM relation), and the relation between the AGN continuum luminosity and the H α line luminosity (i.e., L 5100 L relation) from Greene & Ho (2005),
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we can deriveM BH from our measurements based on the spectroscopic decomposition in the H α region. With the line dispersion ( σ ) and luminosity (L ) of the broad component of H α , the black hole mass can be estimated as follows:
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For the virial factor we adopted
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, which is based on the recent calibration using the combined sam- ple of the quiescent galaxies and reverberation-mapped AGNs (Woo et al. 2013). Note that the systematic uncertainty of the virial factor is 0.31 dex (see Woo et al. 2010) and that black hole mass can easily vary by a factor of 2–3, depending on the virial factor calibra- tion (see Park et al. 2012). Thus, the quoted black hole mass should be treated with caution. In Table 1 , we provide the virial product, instead of the black hole mass, which can be determined by multiplying the virial product with the virial factor.
Physical parameters of 142 missing type 1 AGNs
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Notes. Column 1: Object name. Column 2: Redshift. Column 3: FWHM velocity of the broad component of the Hα emission line in km s−1. Column 4: Luminosity of the broad component of the Hα emission line in log scale (erg s−1). Column 5: Bolometric luminosity in log scale (erg s−1). Column 6: Virial Product in log scale (M). Column 7: Eddington ratio in log scale. Column 8: Stellar velocity dispersion in km s−1 adopted from the SDSS catalogue.
The Eddington luminosity of each object was calculated with the equation LEdd = 1.25 × 10 38 M BH (erg s −1 ) (Wyithe & Loeb 2002). We used the luminos- ity of the broad H α line as a proxy for the AGN bolo- metric luminosity Utilizing the relation between the lu- minosity of broad H α and the continuum luminosity at 5100Å (Greene & Ho 2005), and the bolometric correc- tion 9.26 for L5100 (Richards et al. 2006), we derived the bolometric luminosity as follows,
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4. RESULTS
- 4.1. Sample Properties
Out of the parent sample of 4 113 type 2 AGNs in the local universe (0.02 < z <0.05), we find a total of 142 misclassified type 1 AGNs based on the presence of the broad component of H α (FWHM > 1000 km s −1 ). The fraction of misclassified AGNs is ∼3.5% of the parent sample. 25 objects have been previously referenced in the literature (see Greene & Ho 2004, 2007; Xiao et al. 2013; Reines et al. 2013), indicating a novel discovery of missing type 1 AGNs.
The distribution of the measured properties, i.e., the FWHM and luminosity of the broad H α component, and black hole mass, are presented in Figure 3 . The newly identified type 1 AGNs have a large range of the braod H α FWHM velocities, ranging from 1700 to 19 090 km s −1 . The mean line width of broad H α is log FWHM = 3.52±0.21. In the case of the luminos- ity, all candidates are relatively low-luminosity AGNs with H α luminosity lower than 10 42 erg s −1 . The mean broad H α luminosity is log L = 40.51 ± 0.34. The black hole mass of the sample ranges from ∼10 5.5 to ∼10 8.5 M with a mean log M BH /M = 6.94 ± 0.51, while the mean Eddington ratio is log L bol /L Edd ) = −2.00±0.40. Compared to the local supermassive black hole population, the misclassified AGNs have a similar black hole mass range with a peak at ∼10 7 M (Heck- man & Best 2014), while the Eddington ratio of the sample is relatively lower than the one of high luminos- ity QSOs. Table 1 provides the list of 142 misclassified type 1 AGNs along with the measured physical param- eters. Figure 4 presents the distribution of the misclas- sified type 1 AGNs in the Lbol MBH plane. Overall, the distribution of the sample is similar to that of low luminosity type 1 AGNs (e.g., Woo & Urry 2002).
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Bolometric luminosity vs. black hole mass for 142 misclassified type 1 AGNs. Dashed lines represent fixed Eddington ratios.
- 4.2. Comparison with MPA-JHU
In this section, we compare our new measurements of the H α line luminosity with that from the the MPA- JHU catalog as shown in Figure 5 . Since the broad component of H α was included in our analysis, we ex- pect that our measurements of the narrow H α line lu- minosity is reliable, while the MPA-JHU measurements are likely to be overestimated if the broad H α is not considered in the fitting process.
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Comparison of the narrow Hα flux measurements of 142 misclassified type 1 AGNs adopted from the MPAJHU catalog and from this study.
We find a clear trend that the narrow H α emission line flux measurements provided by the MPA-JHU cat- alog is larger than that of our measurement, particu- larly at the low luminosity regime. The overall overes- timation of the narrow H α line flux can be interpreted as the contribution of the broad H α , since the narrow and broad components were not decomposed, although the line flux can vary depending on how the contin- uum around the H α region was determined. The differ- ence is less significant for AGNs with a strong narrow H α line, presumably due to the weaker contribution of the broad H α component. These results demonstrate that the line flux measurements of the narrow H α can be significantly uncertain when a broad component is present and that decomposing and subtracting a broad H α component from narrow lines (i.e., H α and N II ) is necessary for misclassified type 1 AGNs.
- 4.3. Velocity offset of the emission lines
We investigate the kinematic properties of the ionized gas, by calculating the velocity offset of the [O III ] and the H α lines with respect to the systematic velocity, which is measured from stellar absorption lines. In the case of H α , we use the narrow and broad components separately, since the physical scale of these two compo- nents is clearly different. In Figure 6 , we present the distribution of the velocity offset for each line. For the O III line, we used the flux centroid of the line profile as the velocity of the line if a double Gaussian model was used for the fit. The O III line shows large velocity offsets ranging from ∼ −350 to ∼100 km s −1 , with a mean −32 km s −1 and rms 67 km s −1 . In addition, the distribution of the [O III ] velocity offset is asym- metric, indicating that more than a half of the objects has blueshifted [O III ] with relatively large velocities. The detected velocity offset with respect to the sys- temic velocity can be interpreted as due to outflows in the narrow-line region, as various previous studies have used the O III velocity offset as an outflow indicator (e.g., Boroson 2005; Komossa et al. 2008; Crenshaw et al. 2010; Bae & Woo 2014)
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Distribution of the velocity offset with respect to the systemic velocity measured from stellar absorption lines. The OIII line (left) presents on average a larger velocity offset than the narrow component of Hα (center). The broad component of Hα shows a significantly larger velocity offset than the narrow lines (right). In each panel, the mean and rms of the velocity offset is presented.
In the case of the narrow H α component, most galax- ies show relatively small velocity offsets with a mean velocity offset. These results of O III and H α velocity offsets are consistent with previous studies of type 2 AGNs (Komossa et al. 2008; Bae & Woo 2014).
In contrast, we detected large velocity offsets in the broad component of H α , with a mean velocity 119 km s −1 and with a rms of 305 km s −1 , which is much larger than that of narrow emission lines (H α and O III ). The nature of the velocity offset of the broad line is not clear without spatially resolved measurements. We speculate that it may be due to the orbital motion of the black hole and accompanied BLR gas or the inflow/outflow motion of the gas in the BLR. More detailed studies are required to identify the nature of the velocity offset of broad emission lines.
- 4.4. Kinematics of the ionized gas
In Figure 7 we present the velocity dispersion of the ionized gas. For O III we calculated the second moment of the total line profile as the velocity dispersion when we used a double Gaussian model for the fit. In the case of N II and S II , we used the line dispersion of the best- fit Gaussian model. Since we used the same Gaussian model for N II and S II , we only present the velocity dispersion of N II .
Compared to the N II lines, the velocity dispersion of O III is much larger, by a factor 1.8 in average. The larger O III velocity dispersion is expected from the presence of a wing component in the line profile. How- ever, once we remove the wing component and measure the velocity dispersion from the narrower core compo- nent from the best-fit double Gaussian models (bottom panel in Figure 7 ), the velocity dispersions of N II and O III become consistent albeit with significant scatter (∼30%). The mean difference of the velocity dispersion between N II and the O III core component is only ∼1%, confirming that the core component of O III and low- ionization lines (i.e., N II and S II ) have similar kinemat- ics, presumably governed by the gravitational potential of the galaxy bulge (see also Komossa et al. 2008).
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Comparison of the line dispersion of NII with that of total (top) and core component of [OIII] (bottom). While the OIII line is clearly broader than NII due to the strong wing component, the core component of OIII shows consistent line dispersion compared to NII.
In Figure 8 we directly compare the velocity disper- sion of N II and the core component of O III with stel- lar velocity dispersion. The velocity dispersion of N II is on average smaller than the stellar velocity disper- sion by 14%, while the scatter is ∼29%. In the case of the core component of O III (bottom panel in Fig-ure 8 ), the velocity dispersion is also smaller than the stellar velocity dispersion by 13%, however the scatter is considerably larger (∼43%). These results suggest that the velocity dispersions of narrow emission lines are on average consistent with stellar velocity disper- sions, confirming the results of previous studies (e.g., Nelson & Whittle 1995). Thus, the width of N II (or O III core component) may be used as a proxy for stel- lar velocity dispersion. However, if the velocity disper- sions of the narrow-emission lines are used instead of the directly measured stellar velocity dispersions, sig- nificantly larger uncertainty would be introduced due to the large scatter shown in Figure 8 .
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Comparison of the stellar velocity dispersion with the velocity dispersions of NII (top) and the core component of [OIII] (bottom).
The large scatter between emission and absorption lines can be attributed to the contribution from outflow or inflow motion of the gas in the NLR, which seems to preferentially affect the O III- emitting gas. In addition, we note that the measured stellar velocity dispersion from the SDSS spectra, which were extracted with a 3′′ aperture, can suffer from rotational broadening in the stellar absorption lines, depending on the orien- tation of the stellar disk and the relative strength of the rotation and random velocities as demonstrated by the spatially resolved measurements (Kang et al. 2013; Woo et al. 2013) and the simulated results with various line-of-sight measurement (Bellovary et al. 2014). The larger stellar velocity dispersion relative to the velocity dispersion of N II, by 0.06 dex (14%), may indicate an overestimate of the stellar velocity dispersion due to the rotation/inclination effect.
5. DISCUSSION AND CONCLUSIONS
We presented a sample of 142 misclassified type 1 AGNs identified out of a parent sample of 4 113 type 2 AGNs at 0.02 < z < 0.05, selected from the SDSS DR 7 based on the emission-line flux ratios. The fraction of the mis- classified type 1 AGNs among type 2 AGNs is ∼3.5%; this should be considered as a lower limit because we conservatively identified the broad H α component by excluding AGNs that require a broad component with relatively small width. If we extrapolate the fraction of the misclassified type 1 AGNs, 3.5%, to higher redshift, it is expected that a large number of AGNs could be misclassified as type 2 AGNs in the SDSS DR7 catalog. The discovery of the missing type 1 AGN population will shed light on understanding the low-mass, low- luminosity AGNs and studying AGN population and their properties.
The newly identified type 1 AGN sample has a mean black hole mass log (M BH /M )=6.94 ± 0.51 based on the most recent single-epoch black hole mass calibrator – although the precise black hole mass values depend on the virial factor. The mean broad H α luminosity of the sample is log (L /(erg s −1 ) = 40.50 ± 0.35, and the mean Eddington ratio is log L bol / LEdd = −2.00±0.40. The low Eddington ratios of the sample imply that the AGN continuum is too weak to change the host galaxy color, which is consistent with the relatively red color of the targets shown in the SDSS images.
We investigated the velocity offset of each emission line with respect to the systemic velocity measured from stellar absorption lines. We find that the O III lines show relatively large velocity offsets while the veloc- ity offsets of the H α lines are weaker than for O III , indicating that the O III -emitting gas is influenced by outflows more strongly. The velocity dispersions of the Nii lines and the O III core components are consistent with each other and with stellar velocity dispersions, albeit with significant scatter, suggesting that the kine- matics of the gas in the NLR is mainly governed by the large scale gravitational potential (i.e., the galaxy bulge), while outflow/inflowmotions can vary the veloc- ity dispersion of narrow emission lines. The kinematic properties of the ionized gas of the sample are similar to those of the general type 1 AGN population, support- ing the idea that these objects are simply misclassified type 1 AGNs.
http://www.mpa-garching.mpg.de/SDSS/
Acknowledgements
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST; No. 2012- R1A2A2A01006087). J. H. W. acknowledges the sup- port by the Korea Astronomy and Space Science In- stitute (KASI) grant funded by the Korea government (MEST). by the Korea government (No. 2012-006087). J. G. K. acknowledges the support by the 2012 R&E Programof Gyeonggi Science High School for the Gifted (GSHS).
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