SDSS_DR8.Supercluster table

We have constructed a set of supercluster catalogues for the galaxies from the SDSS survey data release 8 (DR8) flux-limited samples. To delineate superclusters, we calculated luminosity density fields using the B3 spline kernel with 8 Mpc/h radius and define regions with densities over a selected threshold as superclusters. We are utilising almost the whole volume of the sample. We created two types of catalogues, one with an adaptive local threshold and a set of catalogues with different global thresholds. Construction of the catalogue is described in detail in Liivamägi et al. (2012).

Table structure

sclnamechar(12) supercluster name
supercluster identification number
dleveldecimal(3,1)stat.param*dmeanluminosity density threshold
adapttinyintmeta.codeadaptive flag: 1 denotes the adaptively assigned density threshold, 0 otherwise
ngalintmeta.numbernumber of galaxies in supercluster
ngroupintmeta.numbernumber of groups in supercluster
volumefloatphys(Mpc/h)^3supercluster volume, number of grid cells above threshold times grid cell volume
lum_tot_denfloatphys.luminosity10+10Lsunsupercluster luminosity, sum of grid cell values
lum_tot_galfloatphys.luminosity10+10Lsunsupercluster luminosity, sum of weighted galaxy luminosities
den_peakfloatstat.param*dmeanpeak density, maximum grid cell value in supercluster
ra_peakdoublepos.eq.radegright ascension (J2000) of the highest density peak
dec_peakdoublepos.eq.decdegdeclination (J2000) of the highest density peak
dist_peakdoublepos.distanceMpc/hdistance to the highest density peak
ra_mcendoublepos.eq.radegright ascension (J2000) of the centre of luminosity
dec_mcendoublepos.eq.decdegdeclination (J2000) of the centre of luminosity
dist_mcendoublepos.distanceMpc/hdistance to the centre of luminosity
crd_x_peakdoublepos.cartesian.xMpc/hCartesian x-coordinate of the highest density peak, calculated from SDSS eta/lambda
crd_y_peakdoublepos.cartesian.yMpc/hCartesian y-coordinate of the highest density peak, calculated from SDSS eta/lambda
crd_z_peakdoublepos.cartesian.zMpc/hCartesian z-coordinate of the highest density peak, calculated from SDSS eta/lambda
crd_x_mcendoublepos.cartesian.xMpc/hCartesian x-coordinate of the centre of luminosity, calculated from SDSS eta/lambda
crd_y_mcendoublepos.cartesian.yMpc/hCartesian y-coordinate of the centre of luminosity, calculated from SDSS eta/lambda
crd_z_mcendoublepos.cartesian.zMpc/hCartesian z-coordinate of the centre of luminosity, calculated from SDSS eta/lambda
scl_diamfloatphys.size.diameterMpc/hdiameter, maximum distance between supercluster galaxies
galid_markintmeta.idmarker galaxy ID in Tago et al. (2010) catalogue
scl_conffloatstat.snrconfidence estimation; average density field signal-to-noise ratio over galaxies in supercluster
edgetinyintmeta.codemask boundary flag: 1, if supercluster is in contact with edge of mask, and 0, if not
componentssmallintmeta.numbernumber of objects that will split from current supercluster on higher density thresholds
v3floatstat.valuemaximum value of the fourth Minkowski functional, clumpiness (Martínez&Saar 2002)
k1floatstat.valueshapefinder K1, planarity (Sahni et al. 1998)
k2floatstat.valueshapefinder K2, filamentarity (Sahni et al. 1998)

*dmean — density threshold and maximum peak densities are given in the units of mean luminosity density in the density field mask. The mean density value for SDSS DR8 is dmean=1.647821E-02 10+10Lsun/(Mpc/h)^3.

Sample queries

  1. Get all superclusters at fixed density threshold D = 5.0:
    SELECT * FROM SDSS_DR8.Supercluster WHERE dlevel=5.0
  2. Select all superclusters at adaptevely calculated density thresholds:
    SELECT * FROM SDSS_DR8.Supercluster WHERE adapt=1
  3. Get the number of superclusters at different density thresholds:
    SELECT dlevel,COUNT(*) FROM SDSS_DR8.Supercluster GROUP BY dlevel
  4. Get all galaxies belonging to the supercluster Scl 27 at fixed density threshold D = 5.0. This query joins the Galaxy and SclGalaxy tables, assigns table aliases for convenience, and fetches all columns from the Galaxy table.
    SELECT gal.*
    FROM SDSS_DR8.Galaxy AS gal
    JOIN SDSS_DR8.SclGalaxy AS sclgal USING (galid)
    WHERE sclgal.sclid=27 AND sclgal.dlevel=5.0
  5. Get all galaxy groups from superclusters found with the adaptive density threshold where the luminosity lum_tot_gal is larger than 300. This query joins the GalGroup, SclGroup and Supercluster tables, assigns table aliases for convenience, and fetches all columns from the GalGroup table together with the supercluster ID sclid and density level dlevel.
    SELECT gr.*, scl.sclid, scl.dlevel
    FROM SDSS_DR8.GalGroup AS gr
    JOIN SDSS_DR8.SclGroup AS sclgr USING (groupid)
    JOIN SDSS_DR8.Supercluster AS scl USING (sclid,dlevel)
    WHERE scl.lum_tot_gal > 300 AND scl.adapt=1