A Comprehensive Study of 2000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey. I. The Sample

By Hongyan Zhou, Ting-gui Wang, W. Yuan, Honglin Lu, Xiaobo Dong, Junxian Wang, Youjun Lu. 2006

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This is the first paper in a series dedicated to the study of the emission-line and continuum properties of narrow line Seyfert 1 galaxies (NLS1s). We carried out a systematic search for NLS1s from objects assigned as "QSOs" or "galaxies" in the spectroscopic sample of the Sloan Digital Sky Survey Data Release 3 (SDSS DR3) by a careful modeling of their emission lines and continua. The result is a uniform sample comprising ~2000 NLS1s. This sample dramatically increases the number of known NLS1s by a factor of ~10 over previous compilations. This paper presents the parameters of the prominent emission lines and continua, which were measured accurately with typical uncertainties <10%. Taking advantage of such an unprecedented large and uniform sample with accurately measured spectral parameters, we carried out various statistical analyses, some of which were only possible for the first time. The main results found are as follows. (1) Within the overall Seyfert 1 population, the incidence of NLS1s is strongly dependent on the optical, X-ray, and radio luminosities as well as the radio loudness. The fraction of NLS1s peaks around SDSS g-band absolute magnitude Mg ~ -22 mag in the optical and ~1043.2 ergs s-1 in the soft X-ray band, and decreases quickly as the radio loudness increases. (2) On average the relative Fe II emission, R4570 = Fe λλ4434-4684/Hβ, in NLS1s is about twice that in normal active galactic nuclei (AGNs) and is anticorrelated with the broad component width of the Balmer emission lines. (3) The well-known anticorrelation between the width of broad low-ionization lines and the soft X-ray spectral slope for broad line AGNs extends down to FWHM ~ 1000 km s-1 in NLS1s, but the trend appears to reverse at still smaller line widths. (4) The equivalent width of Hβ and Fe II emission lines are strongly correlated with the Hβ and continuum luminosities. (5) We do not find any difference between NLS1s and normal AGNs in regard to the narrow line region. (6) We have examined the black hole mass versus stellar velocity dispersion (MBH-σ*) relation for a subsample of 308 NLS1s for which σ* could be measured directly from fitting the starlight in the SDSS spectra with our stellar spectral templates. A significant correlation between MBH and σ* is found, but with the bulk of black hole masses falling below the values expected from the MBH-σ* relation for normal galaxies and normal AGNs. This result indicates that NLS1s are underage AGNs, where the growth of the SMBH lags behind the formation of the galactic bulge. (7) We also find that the FWHM of [N II] line is well correlated with σ* in 206 NLS1s, for which both parameters could be derived with reasonable accuracy. The [N II] width can predict the stellar velocity dispersion to an accuracy of ~30%. A similar MBH-σ* relation could be found for a larger sample of 613 NLS1s on making use of the more reliable measurements of FWHM[N II].

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/3976a5629bb7f3bb99602d181c45023b1f385f23

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Citations in the corpus

A Combined Optical and X-ray Study of Unobscured Type 1 AGN. I. Optical Spectra and SED Modeling (2011, methodology): “…effects, as implied by the simplest version of AGN unification model (Antonucci 1993), but also result from a wide range in basic physical parameters, such as black hole mass and accretion rate (e.g. Boroson & Green 1992; Boller, Brandt & Fink 1996; Done & Gierliński 2005; Zhou et al. 2006).”
The Fermi blazars' divide (2009, unknown): “In fact, the object PMN 0948+0022 (αγ = 1.6 ± 0.14 andLγ ∼ 1047 erg s−1) is a NLSy1, with a black hole mass around108M⊙ (see Abdo et al. 2009b and Zhou et al. 2006).”
Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies (2009, background): “These eight SDSS spectroscopic objects have not previously been identified as NLS1s,(e.g., Williams et al. 2002; Zhou et al. 2006).”
RADIO-LOUD NARROW-LINE SEYFERT 1 AS A NEW CLASS OF GAMMA-RAY ACTIVE GALACTIC NUCLEI (2009, background): “Although based on a small sample of objects (128), these results have been confirmed by studies on larger samples from the SDSS (Zhou et al. 2006; Whalen et al. 2006).”
On the Nature of Seyfert Galaxies with High [O III] λ5007 Blueshifts (2008, background): “…MBH − σ plane, which was the focus of a number of subsequent studies (Wang & Lu 2001, Wandel 2002, Botte et al. 2004, 2005, Bian et al. 2004, Grupe & Mathur 2004, Barth et al. 2005, Greene & Ho 2005, Mathur & Grupe 2005a,b, Zhou et al. 2006, Ryan et al. 2007, Watson et al. 2007, Komossa & Xu 2007).”
Properties of flat-spectrum radio-loud Narrow-Line Seyfert 1 Galaxies (2014, methodology): “A larger study by Zhou et al. (2006) based on SDSS Data Release 3 resulted in a sample of 2011 NLS1s, about 14% of all the AGN with broad emission lines.”
FERMI/LARGE AREA TELESCOPE DISCOVERY OF GAMMA-RAY EMISSION FROM A RELATIVISTIC JET IN THE NARROW-LINE QUASAR PMN J0948+0022 (2009, methodology): “…Bank radio survey at 5 GHz (Bennett et al. 1986), this quasar is part of the sample drawn from the SDSS and FIRST (Faint Images of the Radio Sky at Twenty-Centimeters) in a systematic search for radio loud NLS1 objects (Zhou et al. 2003, Komossa et al. 2006, Zhou et al. 2006, Yuan et al. 2008).”
THE SIMULTANEOUS OPTICAL-TO-X-RAY SPECTRAL ENERGY DISTRIBUTION OF SOFT X-RAY SELECTED ACTIVE GALACTIC NUCLEI OBSERVED BY SWIFT (2010, result): “As expected from previous work (e.g. Boller et al. 1996; Brandt et al. 1997; Grupe et al. 1999; Leighly 1999b; Grupe 2004; Zhou et al. 2006) a clear anti-correlation between the width of Hβ and αX is found.”
Broad-line Balmer decrements in blue active galactic nuclei (2007, background): “…to fit emission lines (e.g., Boroson & Green 1992, Marziani et al. 2003); or first to fit and subtract simultaneously the continuum and the Fe II emission multiplets (socalled “pseudo-continuum”) and then to fit other emission lines (e.g., Dong et al. 2005, Greene & Ho 2005, Zhou et al. 2006).”
The Effect of Radiation Pressure on Virial Black Hole Mass Estimates and the Case of Narrow-Line Seyfert 1 Galaxies (2008, methodology): “— Histogram of theMBH,vir/MBH,corr ratio for the Zhou et al. (2006) sample of 33 NLS1 galaxies (see text).”