Supplemental materials of
A Catalog of Quasar Properties from SDSS DR7
Shen et al. (2011), ApJS, 194, 45, arXiv:1006.5178

Updates   Download the catalog   QA plots   Papers   Dereddened Spectra

This page contains information about the DR7 quasar property catalog (described in the above paper), which is an extension of the SDSS DR7 quasar catalog. Here you can find the catalog and its future updates, as well as Quality Assessment (QA) plots for individual spectral fits. Due to the large number of entries in this catalog, a fits table is provided. If you find bugs in the catalog or if you have any suggestions, please let me know.

This page is now mirrored at SDSS DAS .

In this document:

• A few Quick Notes
• Catalog Description
  1. Main Columns
  2. Special Interest Objects
  3. Ancillary Columns
• Quick Plots
• Comparison with the DR5 Compilation
• Update Notes

A few Quick Notes:

• The catalog currently only contains emission line measurements for Halpha ([NII] and [SII]), Hbeta ([OIII]), MgII and CIV. There are other interesting lines (such as CIII]) which are not yet fitted. You may find measurements for these additional lines from the SDSS pipeline outputs (either spec1d or specBS) accessible from CAS.
• I tried to flag objects with special interests (such as disk emitters, broad absorption line quasars, double-peaked [OIII] objects, etc.), but the completeness of such objects is not quantified (since the identification is largely based on visual inspection) and some objects may have been missed. Also, there may be needs to add new categories of special quasars. For these reasons, I may update the lists of special quasars (in particular the special interest flag) in future updates.
• As the fits were done automatically, there will be bad fits, especially for noisy spectra or peculiar objects. If you care for robust measurements of particular objects, check the reported measurement uncertainties, or (even better), check the QA plots.
• Like other line measurements, the measurements reported here rely on a set of fitting recipes and hence have their own limitations and systematics. Moreover, the derived quantities (such as bolometric luminosities, virial BH masses, etc), are model-dependent. Keep these caveats in mind when you use these measurements.
• Virial BH masses are NOT true masses!! we strongly caution that you should NOT directly interpret using these virial masses without considering their uncertainty and their inherent dependences on luminosity. Such direct interpretations will usually lead to biased or even spurious results!
• Finally, this temporary web host is limited in disk space, so we couldn't provide the dereddened (for Galactic extinction) spectra here. You can retrieve dereddened spectra at the mirror site at SDSS DAS.

If you use any of these data, please reference the following papers (do not reference this webpage because it is only a temporary host!):

Schneider et al. (2010), AJ, 139, 2360; Shen et al. (2011), ApJS, 194, 45, arXiv:1006.5178

Catalog Description

The detailed catalog description can be found in the paper. Here is a summary of cataloged quantities for the fits version.

Main columns

Special interest flag (in hex and decimal)

  DISK_EMITTER                = 0x1          = bit # 0 =        1		(An example, 1684-290-53239) 
  DISK_EMITTER_CANDIDATE      = 0x2          = bit # 1 =        2
  DOUBLE_PEAKED_OIII          = 0x4          = bit # 2 =        4		(An example, 1320-343-52759)

Select special objects in IDL:
IDL> bh = mrdfits('filename', 1) ; filename is the path of the fits catalog
IDL> ind = where( (bh.special_interest_flag AND 2L^0) NE 0 ) ; return the indices of disk emitters
IDL> ind = where( (bh.special_interest_flag AND 2L^0+2L^1) NE 0 ) ; return the indices of disk emitters and disk emitter candidates
IDL> ind = where( (bh.special_interest_flag AND 2L^2) NE 0 ) ; return the indices of double-peaked [OIII] objects

Ancillary columns

The following additional columns were not included in the published paper. These columns were added only for the convenience of users; please cite the original papers on these data upon usage.

NB: Here the cross-matching with other survey catalogs only reports the closest matches; the matching radii are larger than the typical astrometric uncertainties reported by WISE and GALEX, but comparable to the angular resolution in the shortest waveband. You may want to use the cataloged OFFSET values to refine the cross-matched sources.

Quick Plots

Left: Distribution of DR7 quasars in the redshift-luminosity space; Right: Distribution of DR7 quasars in the redshift-virial mass plane.

Balmer decrement based on a subset of quasars have both Halpha and Hbeta measurements. Left: For narrow emission lines; Right: For broad emission lines.

Distribution of the flux ratio of the [OIII]4959,5007 doublet. We didn't fix the flux ratio of the [OIII] doublet during the fits, but the resulting distribution peaks at the expected theoretical value.

Comparison with the DR5 Compilation (Shen et al. 2008)

This DR7 compilation is much more complete than our previous DR5 compilation. We have now included line fits with multiple Gaussians for the broad Hbeta and broad MgII; these fits provide a more accurate fit to the broad line profile. We also compiled quantities such as equivalent widths, line luminosities, iron emission strengths etc. in the catalog. Halpha properties are also added in this compilation. Finally, we reported measurement errors estimated from Monte Carlo trials of mock spectra. Except for CIV, we have adopted different procedures to measure the broad Hbeta and MgII, and used different fiducial scaling relations to compute Hbeta- and MgII-based virial BH masses (but we have retained the single-Gaussian broad line fits as we did for DR5; see the paper for details).

Even for the single-Gaussian fits to the broad lines, there are still some minor changes compared to the DR5 vesion:

• We have used a 0.7-0.3-0.7 cosmology; for DR5 we used 0.74-0.26-0.71.
• We dereddened the spectra for Galactic extinction first before we fit for the lines; for DR5 we fit the lines using the original spectra and then corrected the fitted luminosity for Galactic extinction.
• We used two Gaussians to fit for the [OIII]4959,5007 lines, where the second Gaussian is to account for the blue wing often seen in [OIII].
• We masked out (pixel) outliers to improve MgII fits for objects with narrow associated MgII absorptions.
• We now report everything, while for DR5 we imposed a S/N cut and a reduced chi2 cut.

Nevertheless, the DR7 measurements are fully consistent with the DR5 measurements with the same fitting technique.

Finally, we did not compare in detail our measurements with the CAS pipeline (spec1d) measurements, for which the continuum+line fitting procedure is more restrictive than ours. Some limited comparison of the CIV line between the two sets of measurements shows that the CAS pipeline CIV EWs are systematically smaller than our values by about 0.1-0.2 dex, likely caused by the spec1d pipeline fitting recipe.

Update Notes

• 2011-05-09: Added ancillary columns 158-162 (including GALEX photometry); [dr7_bh_May09_2011.fits.gz]
• 2011-05-01: Added ancillary columns 143-157; updated the paper; [dr7_bh_May01_2011.fits.gz]
• 2010-06-25: Catalog online; [dr7_bh_Jun25_2010.fits.gz]

Last modified: May 2011 by Yue Shen