The 6dF Galaxy Redshift Survey: Status Report and Data Release 2 Heath Jones ANU/AAO Will Saunders AAO Mike Read Edinburgh Matthew Colless AAO 100,0 00 REDSHIFTS
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The 6dF Galaxy Redshift Survey:Status Report and Data Release 2
Heath JonesANU/AAO
Will SaundersAAO
Mike ReadEdinburgh
Matthew CollessAAO
100,000REDSHIFTS
The 6dF Galaxy Survey: The 6dFGS is designed to be the first of a new
generation of combined z+v-surveys, combining… NIR-selected redshift survey of the local universe Peculiar velocity survey using FP distances Additional redshift surveys of other ‘interesting’
source samples.
The 6dF Galaxy Survey: The 6dFGS is designed to be the first of a new
generation of combined z+v-surveys, combining… NIR-selected redshift survey of the local universe Peculiar velocity survey using FP distances Additional redshift surveys of other ‘interesting’
source samples.
Survey strategy… survey whole southern sky with |b|>10° primary z-survey: 2MASS galaxies to Ktot<12.75 secondary samples: H<13, J<13.75, r<15.6,
b<16.75 11 additional samples: radio, X-ray, IRAS… v-survey: ~15,000 brightest early-type galaxies
Selection in the NIR (J,H,K) minimizes extinction effects of extinction - galaxies can be selected over |b|>10°
Advantages - NIR selection
Selection in the NIR (J,H,K) minimizes extinction effects of extinction - galaxies can be selected over |b|>10°.
NIR luminosity is very closely correlated with total stellar mass, and so yields the stellar mass function.
log (Mstars/h-2M)
Advantages - NIR selection
Cole et al (2001)
Selection in the NIR (J,H,K) minimizes extinction effects of extinction - galaxies can be selected over |b|>10°.
NIR luminosity is very closely correlated with total stellar mass, and so yields the stellar mass function.
Advantages - Sky Coverage
2dFGRS
SDSS
The 6dFGS has 8x the sky coverage of the 2dFGRS and twice the coverage of SDSS.
Selection in the NIR (J,H,K) minimizes extinction effects of extinction - galaxies can be selected over |b|>10°.
NIR luminosity is very closely correlated with total stellar mass, and so yields the stellar mass function.
Advantages - NIR selection
The 6dFGS has 8x the sky coverage of the 2dFGRS and twice the coverage of SDSS.
Traditionally, most redshift surveys have been optically selected and therefore favoured late-type galaxies. In contrast, the NIR selection of 6dFGS is biased towards the redder early-type galaxies needed for the Peculiar Velocity Survey.
Target Allocation Sample Priority Total Sampling
2MASS Ks < 12.75 8 113988 94.1%
2MASS H < 13.05 6 3283 91.8%
2MASS J < 13.75 6 2008 92.7%
SuperCosmos rF<15.7 6 9199 94.9%
SuperCosmos bJ<17.0 6 9749 93.8%
Target allocation 92% or better for the primary and secondary samples.
Number of Tiled SourcesNumber of Sources on Sky
Target Allocation Sample Priority Total Sampling
2MASS Ks < 12.75 8 113988 94.1%
2MASS H < 13.05 6 3283 91.8%
2MASS J < 13.75 6 2008 92.7%
SuperCosmos rF<15.7 6 9199 94.9%
SuperCosmos bJ<17.0 6 9749 93.8%
Shapley 6 939 85.7%
ROSAT All-Sky Survey 6 2913 91.7%
HIPASS (> 4-sigma) 6 821 85.5%
IRAS FSC 6 10707 94.9%
Denis J < 14 5 1505 93.2%
Denis I < 15 5 2017 61.7%
2MASS AGN 4 2132 91.7%
Hamburg-ESO Survey 4 3539 90.6%
NOAO-VLA Sky Survey
4 4334 87.6%
Target allocation 92% or better for the primary and secondary samples.
Additional target samples extend science and fully exploit survey: 2MASS NIR sky survey DENIS NIR sky survey SuperCosmos galaxy
catalogs ROSAT All-Sky Survey
(RASS) HI Parkes Sky Survey
(HIPASS) IRAS Faint Source Catalog
(FSC) NVSS and SUMSS radio
surveys Hamburg-ESO QSO survey
V grating: = 5 – 6 A
• Q=1 - spectra of no value• Q=2 - possible z value• Q=3 - likely z value• Q=4 - z value beyond doubt• Q=5 - textbook example R grating: = 9 – 12 A
• Q=1 - spectra of no value• Q=2 - possible z value• Q=3 - acceptable z value• Q=4 - z value beyond doubt• Q=5 - textbook example
• Q=6 - Galactic source <1%
0 %5 %7 %
77 % 11%
DR 2:
The Observing/Redshifting Cycle
Preparation, observing, reducing follows the lunar cycle
6dFGS
The Observing/Redshifting Cycle
Preparation, observing, reducing follows the lunar cycle
Redshifting takes place in the following lunation
Survey results are updated/reported ~6 weeks after observation
6dFGS
Mt STROMLO
TELESCOPE
6dFGS 2nd Data Release: April 2005DR2
Jan 2002 – October 2004 for public release
89211 spectra; 83014 unique redshifts; 936 fields
36540 more redshifts (37163 more spectra) than DR1
http://www-wfau.roe.ac.uk/6dFGS/
6dFGS Online Database:
Searchable using either SQL query commands or a WWW form
Each source has its own multi-extension FITS file, including 6dF spectrum, brJHK imaging, redshift and photometric information
The different target catalogues are also online, fully searchable and inter-linked
What’s New Since DR1 Data and database structure largely unchanged since DR1
Recent introduction of a QSO template for redshifting (~Aug 05 onwards)
Introduction of Q=6 for confirmed Galactic spectra (formerly Q=2)
Around 7% have disparate irreconcilable proximity and mag rankings
Around 1% have no br match at all
Recalibrated br SUPERCosmos photometry (BMAG, RMAG) and the preservation of the old selection magnitudes (BMAGSEL, RMAGSEL):
• Median z for 6dFGS (z=0.05) is roughly half that of 2dFGRS and SDSS
• When complete, the population of 6dFGS galaxies at low redshifts will be on a par with the other surveys
Number-Redshift Distribution
Redshift Maps: ~90k redshifts
2MASS
547 fields
595 fields
422 fields
1564 fields over southern sky with |b| >10 = 17000
Survey Sky Coverage
Observing strategy has been to cover the sky in thirds: (1) central strip; (2) equatorial strip; (3) southern polar cap.
6df
6df
1564 fields over southern sky with |b|>10 = 17000 Observing strategy has been to cover the sky in thirds: (1) central
strip; (2) equatorial strip; (3) southern polar cap. 1375 fields observed to date – 936 fields from January 02 to
October 04 constituting the Second Data Release
Survey Sky Coverage
Number of Galaxy Redshifts Per Unit
AreaNumber of Galaxy Redshifts + Failures + Remaining Per Unit Area
6dF+ZCAT
+2dF…
Survey Sky Coverage
DR 2 (2005)
DR 1 (2004)
90% of fields > 60%
80% of fields > 80% complete Number of 6dF Galaxy
Redshifts
Number of 6dF Galaxy z’s per
field + Redshift Failures per field
• Breakdown of spectra
extragalactic (85 %)
stellar (3 %)HII regions,PNe (1%)
failures (11 %)
Field Completeness
6dFGS Second Data Release: Summary Jan 2002 – October 2004
89211 spectra; 83014 unique redshifts; 936 fields
Definitive 6dF Survey Paper (DR1): Jones et al (2004), MNRAS 355, 747
DR2 paper Jones et al, PASA
6dFGS Home http://www.aao.gov.au/local/www/6df/
6dFGS Database http://www-wfau.roe.ac.uk/6dFGS/
MOVED !
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