Radio sources in the 6dFGS Tom Mauch

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Radio sources in the 6dFGS Tom Mauch
Elaine Sadler University of Sydney
LAST YEAR

• Main survey science
• Faint end of radio luminosity function for AGN,
  starbursts
• Accurate z0 benchmarks for studies of cosmic
  evolution
• Black hole mass/velocity dispersion relation
  for radio AGN
• Extra targets science
• Compact objects and some galaxies with blue
  colours (QSOs, starburst galaxies)

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All-sky radio continuum surveys
NVSS (Condon et al. 1998) n 1.4 GHz
dec 90o to -40o
SUMSS (Bock et al. 1999 Mauch et al. 2003) n
843 MHz dec -30o to
-90o Currently almost 85 complete (though not
catalogued), will be finished by Dec 2003 Both
surveys have 45 beam, 3-6 mJy det. limit,
position accuracy 1-2
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Since Last Year

• 6 of 6dFGS galaxies in initial data release
  are detected as radio sources.
• 909 Radio sources in 14880 galaxies.
• 394 Additional Target spectra.
• All spectra eyeballed and classified.
• Initial database of radio detections with
  multiwavelength data.

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The Database
Convenient method for searching large dataset!
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Radio sources in the main survey

• 909 radio sources out of 14880 total objects
• 6 Detection Rate!
• Possibly because of our 10 radio optical
  separation cutoff.
• All spectra hand classified (star,Aa,Ae,Aae,SF)
  
• 399 AGN
• 436 Star-Forming
• 71 Unclassifiable
• 3 Stars
• About 50/50 split between AGN and SF in 6dFGS
• (60/40 in 2dFGS)

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Typical Spectra of Faint radio Sources in 6dFGS
(1)

• Absorption line AGN

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Typical Spectra of Faint radio Sources in 6dFGS
(2)

• Emission Line AGN

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Typical Spectra of Faint radio Sources in 6dFGS
(3)

• Star Forming Galaxies IRAS Source
• 0.28 Jy at 60mm

Large fraction of SF galaxies interacting.
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Redshift distribution of 6dFGRS radio sources
2dF Sample
6dF Sample
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Radio emission from star-forming galaxies
6dFGS-NVSS
2dFGS-NVSS
Many faint (lt5mJy) NVSS sources with no IRAS
detection.
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Local radio luminosity function of active and
star-forming galaxies
Distribution of AGN radio luminosities.
Low-luminosity AGN are hard to find
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6dFGS Additional targets

• 6dFGS unallocated fibres placed on NVSS/SUMSS
  radio IDs which have bJlt18 mag but which are not
  in the main sample
• 394 objects in initial data release.
• Stellar objects (foreground stars, QSOs, compact
  galaxies)
• Blue galaxies (starburst, AGN)
• What fraction of the local radio-source
  population is missed because hosts appear
  stellar? Dont need all objects observed, just a
  sub-sample - i.e. flexible

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Detection fractions of additional targets

• Many additional targets are in other additional
  target samples, large fraction have been
  observed!
• 166 stars
• 61 AGN
• 74 Star Forming
• 93 Unknown

About same fraction as in main survey! Possible
BL-Lac population.
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Redshift Distribution of Additional Target
Galaxies

• Median z0.08
• Fainter sources
• Emission line AGN
• Starburst galaxies

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Some interesting Additional Targets (1)

• QSO- No previously recorded redshift.
• Bright radio source (1.8 Jy in NVSS) also PKS
  1955-35

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Some interesting Additional Targets (2)

• Higher-z QSO (4.9 mJy at 1.4 MHz)
• Incorrect z from runz actual z is 0.75

MgII
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Some interesting Additional Targets (3)

• Starburst Galaxy (ULIRG?)
• 43.5 mJy at 1.4 GHz (1024.5 W Hz-1) 0.189 Jy at
  60mm

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Some interesting Additional Targets (4)

• Radio emission from white dwarfs?
• Willes Wu 2003 (astro-ph/0302583) claim white
  dwarf pairs can be strong radio sources!
• 2.9 mJy radio source.
• 3 found in current sample.
• Only 0.1 per deg2 and 10 of these could be radio
  sources.
• Class 2 in the initial data release, but class 4
  spectrum!