Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra, Redshift, and Luminosity Effects

Yip, C. W.; Connolly, Andrew J.; Berk, D. E. vanden; Ma, Zhaoming; Frieman, Joshua A.; SubbaRao, Mark; Szalay, Alexander S.; Richards, Gordon T.; Hall, Patrick B.; Schneider, Donald P.; Hopkins, A. M.; Trump, Jonathan R.; Brinkmann, J.

doi:10.1086/425626

Cited by 237 publications

(222 citation statements)

References 52 publications

(79 reference statements)

Supporting

Mentioning

215

Contrasting

Unclassified

Order By: Relevance

“…However, the decomposition is not performed on a well controlled training sample as in S05 and in the present work (see below), therefore, they do not provide a projection matrix. The analysis performed by Yip et al (2004) is closer to our purpose. They applied a PCA to the 16 707 Sloan Digital Sky Survey DR1 quasar spectra (0.08 < z < 5.41) and reported that the spectral classification depends on redshift and luminosity.…”

Section: Predicted Continuummentioning

confidence: 74%

A principal component analysis of quasar UV spectra atz ~ 3

Pâris

Petitjean

Rollinde

et al. 2011

A&A

121

190

View full text Add to dashboard Cite

From a principal component analysis (PCA) of 78 z ∼ 3 high-quality quasar spectra in the SDSS-DR7 we derive the principal components that characterize the QSO continuum over the full available wavelength range. The shape of the mean continuum is similar to that measured at low-z (z ∼ 1), but the equivalent width of the emission lines is larger at low redshift. We calculate the correlation between fluxes at different wavelengths and find that the emission line fluxes in the red part of the spectrum are correlated with those in the blue part. We construct a projection matrix to predict the continuum in the Lyman-α forest from the red part of the spectrum. We apply this matrix to quasars in the SDSS-DR7 to derive the evolution with redshift of the mean flux in the Lyman-α forest caused by the absorption by the intergalactic neutral hydrogen. A change in the evolution of the mean flux is apparent around z ∼ 3 as a steeper decrease of the mean flux at higher redshifts. The same evolution is found when the continuum is estimated from the extrapolation of a power-law continuum fitted in the red part of the quasar spectrum if a correction derived from simple simulations is applied. Our findings are consistent with previous determinations using high spectral resolution data. We provide the PCA eigenvectors over the wavelength range 1020−2000 Å and the distribution of their weights that can be used to simulate QSO mock spectra.

show abstract

Section: Predicted Continuummentioning

confidence: 74%

A principal component analysis of quasar UV spectra atz ~ 3

Pâris

Petitjean

Rollinde

et al. 2011

A&A

121

190

View full text Add to dashboard Cite

show abstract

“…Variants of E1 were later found in several studies (e.g. Marziani et al 1996;Boroson 2002;Grupe 2004;Kuraszkiewicz et al 2002;Sulentic et al 2000bSulentic et al , 2002Yip et al 2004;Kovačević et al 2010;Kruczek et al 2011;Tang et al 2012;Wang et al 2006).…”

Section: Introductionmentioning

confidence: 82%

“…Interpreting of quasar spectra in the context of a 4D parameter space stemming from eigenvector studies reveals a wide diversity of line profile properties (Sulentic et al 2000a(Sulentic et al , 2007Marziani et al 2003bMarziani et al , 2010 that are most likely driven by L/L Edd , with M BH and source orientation also playing important roles (Boroson & Green 1992;Marziani et al 2001;Yip et al 2004). The 4DE1 (4D eigenvector 1) formalism owes its Now at Instituto de Astronomía, UNAM, Ensenada Campus, Baja California, México. inception to a principal component analysis study of systematic trends in quasar spectra (Boroson & Green 1992) from the the Palomar-Green (PG) survey.…”

Section: Introductionmentioning

confidence: 99%

Is MgIIλ2800 a reliable virial broadening estimator for quasars?

Marziani

Sulentic

Plauchu-Frayn

et al. 2013

A&A

156

View full text Add to dashboard Cite

Context. Broad Mgiiλ2800 and Hβ lines have emerged as the most reliable virial estimators of the black hole mass in quasars. Which is more reliable? Part of the challenge centers on comparing Mgiiλ2800 and Hβ line profiles in order to improve the ±1 dex M BH uncertainties inherent in single-epoch FWHM measures from noisy spectra. Aims. We compare Mgiiλ2800 and Hβ profile measures in the same sources and especially FWHM measures that provide the virial broadening estimator. Methods. We identify 680 bright Sloan Digital Sky Survey Data Release 7 quasars with spectra showing both Mgiiλ2800 and Hβ lines at redshift 0.4 ≤ z ≤ 0.75. The S/N of these spectra are high enough to allow binning in the "four-dimensional (4D) eigenvector 1" optical plane and construction of high S/N composite spectra. Results. We confirm that Mgiiλ2800 shows a profile that is ≈20% narrower as suggested in some previous studies. FWHM measures for Population B sources (i.e., with FWHM of Hβ larger than 4000 km s −1 ) are uncertain because they show complex profiles with at least two broad-line components involving a nearly unshifted broad and redshifted very-broad component. Only the broad component is likely to be a valid virial estimator. If Hβ and Mgiiλ2800 are not corrected for the very broad component then black hole mass M BH values for Population B sources will be systematically overestimated by up to Δ logM BH ≈ 0.3−0.4 dex. We suggest a simple correction that can be applied to the majority of sources. Mgiiλ2800 is the safer virial estimator for Population B sources because the centroid shifts with respect to rest frame are lower than for Hβ. In the broad and very broad component profile interpretation, this is a consequence of the lower very broad to broad component intensity ratio for Mgiiλ2800. Eigenvector-based studies show that effective discrimination of black hole mass and Eddington ratio at fixed redshift is not achieved via luminosity binning but rather by binning in a "4D eigenvector 1" context that reflects different broad line region geometry/kinematics probably driven by the Eddington ratio.

show abstract

“…104 sources). For 18 sources the spectra are available from the Sloan Digital Sky Survey (SDSS) database (York et al 2000;Stoughton et al 2002;Yip et al 2004), Data Release 4−6. For these sources the observations provide uniform and uninterrupted coverage of the key spectroscopic optical diagnostics ratios.…”

Section: O Iii]/[o Ii] Line Ratiomentioning

confidence: 99%

An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

Buttiglione¹,

Capetti

Celotti³

et al. 2010

A&A

252

390

View full text Add to dashboard Cite

In a previous paper we presented a homogeneous and 92% complete optical spectral dataset of the 3CR radio sources with redshift <0.3. Here we use the emission line measurements to explore the spectroscopic properties of the sample. The 3CR sources show a bimodal distribution of excitation index, a new spectroscopic indicator that measures the relative intensity of low and high excitation lines. This unveils the presence of two main sub-populations of radio-loud AGN to which we refer to, following previous studies, as high and low excitation galaxies (HEG and LEG, respectively). In addition to the two main classes, we find one source with a spectrum typical of star forming galaxies, and 3 objects of extremely low level of excitation. All broad-line objects are HEG from the point of view of their narrow emission line ratios and all HEG are FR II radio-galaxies with log L 178 [erg s −1 ] > ∼ 32.8. Conversely LEG cover the whole range of radio power encompassed by this 3CR subsample (30.7 < ∼ log L 178 < ∼ 35.4) and they are of both FR I and FR II type. The brightest LEG are all FR II. HEG and LEG obey to two (quasi) linear correlations between the optical line and extended radio luminosities, with HEG being brighter than LEG in the [O III] line by a factor of ∼10. HEG and LEG are offset also in a plane that compares the black hole mass and the ionizing nuclear luminosity. However, although HEG are associated with higher nuclear luminosities, we find LEG among the brightest radio sources of the sample and with a clear FR II morphology, indistinguishable from those seen in HEG. This suggests that LEG are not simply objects with a lower level of accretion. We speculate that the differences between LEG and HEG are related to a different mode of accretion: LEG are powered by hot gas, while HEG require the presence of cold accreting material. The high temperature of the accreting gas in LEG accounts for the lack of "cold" structures (i.e. molecular torus and broad line region), for the reduced radiative output of the accretion disk, and for the lower gas excitation.

show abstract

Spectral Classification of Quasars in the Sloan Digital Sky Survey: Eigenspectra, Redshift, and Luminosity Effects

Cited by 237 publications

References 52 publications

A principal component analysis of quasar UV spectra atz ~ 3

A principal component analysis of quasar UV spectra atz ~ 3

Is MgIIλ2800 a reliable virial broadening estimator for quasars?

An optical spectroscopic survey of the 3CR sample of radio galaxies withz$\mathsf{<}$ 0.3

Contact Info

Product

Resources

About