2MASS Selected AGN with 6dF

6dF Workshop, April 2005

2MASS Selected AGN with 6dF

Paul Francis (ANU)

Roc Cutri, Brant Nelson (IPAC/CALTECH)

6dF Workshop, April 2005

The Reddest 2MASS Sources

6dF Workshop, April 2005

A good way to find AGN?• Ridiculously simple selection: J-K>2, from

2MASS.

• Greater than 60% efficiency in finding AGN - as good as UVX.

• AGN not detectable with any other method.

• Mostly low redshifts <z> ~ 0.2

6dF Workshop, April 2005

Average spectrum

6dF Workshop, April 2005

Incomplete

• Only have spectra of 700 of the ~ 17,000 2MASS sources with J-K>2.

• Biassed sub-sets only:

• Brighter than K=14: 80% are AGN: mostly Type-1 (broad-line) AGN.

• But does this hold for the fainter ones?

6dF Workshop, April 2005

6dF: Very red population to fainter magnitudes.

6dF Workshop, April 2005

Status as at 2nd Data Release

• 260 sources with spectra.

• Only 100 with quality 3 & 4 spectra.

• 50 with quality 2 spectra,

• 120 with quality 1.

6dF Workshop, April 2005

Quality 4/3: 44 AGN out of 100

6dF Workshop, April 2005

Broad-line

6dF Workshop, April 2005

Narrow-line AGN

6dF Workshop, April 2005

Quality 2: 7 AGN out of 50, with wrong redshifts.

6dF Workshop, April 2005

6dF Workshop, April 2005

Quality 1: only ~4/120 are AGN

6dF Workshop, April 2005

Results

• AGN fraction drops dramatically for these fainter sources: down to ~20%.

• The AGN themselves are very similar to those at brighter K-band magnitudes - ie. mainly Type-1: median redshift ~ 0.2.

• They are simply being swamped by a rising tide of moderate redshift ellipticals and edge-on spiral galaxies.

• 6dF Pipeline gets redshifts wrong for ~20% of broad-line AGNs: primarily those at higher redshifts,

6dF Workshop, April 2005

A wierdo!800 km/s

6dF Workshop, April 2005

Diagnostic Diagrams

6dF Workshop, April 2005

Bj=20.5, absolute magnitude -9.5

6dF Workshop, April 2005

Metal-poor Blue Compact Dwarf?

6dF Workshop, April 2005

6dF Workshop, April 2005

6dF Workshop, April 2005

Conclusions

• Around 20% of 2MASS sources with J-K>2 and K>14 are AGN: predominantly Type-1 AGN.

• These fainter red AGN are very similar to the brighter ones.

• Extrapolating to the whole sky, there should be ~3500 red AGNs with J-K>2 in 2MASS.

6dF Workshop, April 2005

2dF

• Used 2dF to get spectra of all 2MASS sources with J-K>1.2 over 12 square degrees (1200 spectra).

• AGN fraction very low - only 6.5% (though still much higher than in optically selected sample).

• Mostly Type-2 (narrow line) AGNs.• What few Type-1 AGNs we found often were

at higher redshifts. • ~50% would not be found in UVX surveys due

to host galaxy contamination.