The table below gives a summary of all possible columns in our SAG-tables in the database.

There are dark matter halos that have no galaxy counterparts in the SAG-catalog – they just did not produce a physically meaningful galaxy using the SAG model and thus do not appear here.

unique database ID for this table, constructed from file number, snapnum and row in file
snapnumsmallinttime.epochsnapshot number (same as in Rockstar-catalogues)
rockstarIdbigintmeta.idHaloID of dark matter halo as found in Rockstar merger tree (host halo)
forestIdbigintmeta.idID of the corresponding forest halo, for extracting isolated merger forests
GalaxyStaticIDbigintmeta.idID of the galaxy within the SAM. GalID = [Formation Snap]*1E14 + [Num Thread]*1E10 + [Gal Number]
HostHaloIDbigintmeta.idID of host DM halo to which this galaxy last belonged
MainHaloIDbigintmeta.idID of main host dark matter halo
GalaxyTypetinyintmeta.idFlag indicating the type of the galaxy: 0 = main halo central galaxy, 1 = satellite halo central galaxy, 2 = orphan galaxy)
HaloMassfloatphys.masssolMass.h-1mass of the corresponding dark matter halo (M200c) in Rockstar
Vmaxfloatphys.velo.rotatkm.s-1halo circular velocity in physical coordinates, frozen in orphan galaxies
Vpeakfloatphys.velo.rotatkm.s-1halo circular velocity at accretion time in physical coordinates
concentration_NFWfloathalo NFW concentration parameter, frozen in orphan galaxies
xfloatpos.cartesian.xMpc.h-1x-position, comoving
yfloatpos.cartesian.yMpc.h-1y-position, comoving
zfloatpos.cartesian.zMpc.h-1z-position, comoving
vxfloatphys.velockm/sx-component of physical velocity
vyfloatphys.velockm/sy-component of physical velocity
vzfloatphys.velockm/sz-component of physical velocity
MstarSpheroidfloatphys.masssolMass.h-1mass of stars in the spheroid/bulge
MstarDiskfloatphys.masssolMass.h-1mass of stars in the disk
McoldSpheroidfloatphys.masssolMass.h-1mass of gas in the spheroid/bulge
McoldDiskfloatphys.masssolMass.h-1mass of gas in the disk
Mhotfloatphys.masssolMass.h-1hot gas mass
Mbhfloatphys.masssolMass.h-1mass of central black hole
SFRspheroidfloatsolMass.h-1.Gyrstar formation rate of the bulge
SFRfloatsolMass.h-1.Gyrstar formation rate
MagStarSDSSufloatSDSS Camera u Response Function, airmass = 1.3 (June 2001), rest-frame
MagStarSDSSgfloatSDSS Camera g Response Function, airmass = 1.3 (June 2001), rest-frame
MagStarSDSSrfloatSDSS Camera r Response Function, airmass = 1.3 (June 2001), rest-frame
MagStarSDSSifloatSDSS Camera i Response Function, airmass = 1.3 (June 2001), rest-frame
MagStarSDSSzfloatSDSS Camera z Response Function, airmass = 1.3 (June 2001), rest-frame
MZgasSpheroidfloatphys.masssolMass.h-1mass of metals in gas in the spheroid/bulge
MZgasDiskfloatphys.masssolMass.h-1mass of metals in gas in the disk
MZhotHalofloatphys.masssolMass.h-1mass of metals in hot gas in the diffuse halo/atmosphere
MZstarSpheroidfloatphys.masssolMass.h-1mass of metals in stars in the spheroid/bulge
MZstarDiskfloatphys.masssolMass.h-1mass of metals in stars in the disk
MeanAgeStarsfloatGyrmean age of stellar population
NInFilebigintnumber of galaxy in the data file, inside the output group for current snapnum
fileNumintnumber of the file from which the data was uploaded
ixintpos.cartesian.xspatial grid index, x-direction
iyintpos.cartesian.yspatial grid index, y-direction
izintpos.cartesian.zspatial grid index, z-direction
phkeybigintPeano-Hilbert key index of space-filling curve


Get 10 rows from the SAG table


This query retrieves ten (arbitrary) galaxies from the SAG-table.

Get the 10 galaxies with most massive gas disks at z=0

SELECT x, y, z, McoldDisk FROM MDPL2.SAG 
WHERE snapnum=125 ORDER BY McoldDisk DESC

Here 10 galaxies from redshift 0 (snapnum 125) are retrieved, after sorting all galaxies by decreasing disk mass.

Get the evolution of stellar disk mass and metal mass for a given dark matter halo

SELECT s.snapnum, s.redshift, s.rockstarId, s.depthFirstId, s.GalaxyType, s.MstarDisk, s.MZstarDisk
FROM MDPL2.SAG s, MDPL2.Rockstar r
WHERE r.rockstarId = 12663401752
AND s.GalaxyType = 0
AND s.depthFirstId BETWEEN 
    r.depthFirstId AND r.mainLeaf_depthFirstId
ORDER BY s.snapnum

This query will be executed in two steps: first the Rockstar-table is queried to find the depthFirstId and mainLeaf_depthFirstId for a given rockstarId. The depthFirst-ordering allows to extract a whole main branch by selecting all objects with depthFirstIds between the depthFirstId of the object and its mainLeaf_depthFirstId. This is done in the second step: all galaxies with adequate depthFirstIds are extracted. Plotting e.g. s.MstarDisk versus snapnum shows then the evolution of the stellar disk mass with time (snapshot number).
The restriction s.GalaxyType = 0 ensures that only the main galaxy of the halo is extracted.

If the job times out, the query can be done in two steps:

SELECT mainLeaf_depthFirstId, depthFirstId 
FROM MDPL2.Rockstar 
WHERE rockstarId = 12663401752

Use the result table from the query above to get the progenitor galaxies.

SELECT s.snapnum, s.redshift, s.rockstarId, s.depthFirstId, s.GalaxyType, s.MstarDisk, s.MZstarDisk
WHERE s.GalaxyType = 0
AND s.depthFirstId BETWEEN 
    <depthFirstId> AND <mainLeaf_depthFirstId>
ORDER BY s.snapnum

where AND are to be replaced by the values from the first query.

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