The VLA Survey of the Chandra Deep Field South

X-ray Properties of Radio Sources

Shaji Vattakunnel

AGN9 – Ferrara

- University of Trieste

Paolo Tozzi - Francesca Matteucci

25th May 2010

- Deep Radio and X-ray Surveys of the Chandra Deep Field South

- X-ray properties of Radio Sources

- The sub-mJy radio source population

Outline

Flattening of the radio counts below one mJy

Deep Radio and X-ray Surveys

Kellerman et al. 2008

Radio and X-ray observations are efficient in identifying star formation vs nuclear activity at high redshifts.

Flattening below 1 mJyKellerman et al 2008Mainieri et al 2008Tozzi et al 2008Padovani et al 2009

Possibly due to Star Forming Galaxies

VLA/Chandra Surveys1Ms X-ray observation

X-ray luminosity vs Radio power

Padovani et al. 2009

Number Counts

Padovani et al. 2009

Emerging of the star forming galaxies in the sub-mJy populationAnalogous to results found by Gruppioni et al (1999) Prandoni et al (2009)

The Extended Chandra Deep Field South (E-CDFS)

Radio image (1.4 GHz) Radio image (1.4 GHz)

6 pointings of the Very Large Array 1.4 GHz (20 cm)34’.1 x 34’.1 image sensivity 6-8μJy

1571 sources at 4 σ(N. Miller)

The Chandra Deep Field South (CDFS)

[0.3-7 keV]X-ray color image of the 2Ms[0.3-7 keV]X-ray color image of the 2Ms

0.3 – 1 keV1 – 2 keV2 – 7 keV

23 observations (8 years)for a total of 2 Ms - 16’ x 16’ image

Sensitivity: ~10-17 erg cm-2 s-1

448 sources(441 with redshifts)

derived from Luo et al. 2008

The Extended Chandra Deep Field South (E-CDFS)

X-ray color image of the flanking fieldX-ray color image of the flanking field

4 pointings250 ks 9 observations32’ x 32’ image sensitivity ~10-16 erg cm-2 s-1

753 sources (Lehmer et al. 2005)

The 2Ms X-ray Survey

Improvements:

- deeper X-ray image in the CDFS- deeper radio catalog- larger number of found matches

1Ms/VLA (2001) observation

347

266

89

77%

2Ms/EVLA (2007)observation

448

1571

227

95%

X-ray sources in the CDFS

Radio sources in the ECDFS

Radio sources with an X-ray counterpart

redshift available

Identification of X-Ray Counterparts

Counterparts if the separation is less than 3σd , where:

X-RayX-RayOpticalOpticalOpticalOptical RadioRadioRadioRadio

Positional match between X-ray and radio sources

σ2d = σ2

x + σ2r

X-ray rms 0.3” < σx < 1.9”Radio rms estimated at 0.2”

Discriminating AGNs:- X-ray Luminosity

Lx > 1042 erg/s

AGN / SFG discrimination

- Radio Power

Pr > 1024.5 W/Hz

Total sources: 227

# of AGNs: 177

# of SFG candidates: 50

Sources with few counts

Sources with high counts(full spectral analysis)

Luminosity from:

- column density

NH > 1021 cm-2

AGN / SFG discrimination

Star Forming Gal

Low Lum AGNs Absorbed AGNs

Unabsorbed AGNs

Star Formation Rates

The normalization is consistent with Ranalli (2003)There is no evidence of evolution in redshift

Condon (1992)

sources with 0.1 < z < 0.5sources with 0.5 < z < 1.2

0 < z < 1.2

A detailed analysis of the E-CDFS sub-mJy population- X-ray and radio data are a powerfull tool to separate AGNs from SFGs:

~1/4 can be classified as star forming galaxies~ 3/4 as AGNs

- Found a correlation between X-ray and the radio power for star-forming galaxies, in agreement with previous studies

- Evaluation of relation between SFR and X-ray luminosities in our sample in the redshift range 0 < z < 1.2

Conclusions

X-ray stacking of the 1307 radio sources without a catalogued X-ray counterpartCompute the Cosmic Star Formation History

Add data from other wavelenghts (optical, IR)

Another 2Ms set of observations of the CDFS has been approved and will be concluded in the next year. This will allow us the improve our analysis with deeper data.

Thanks for your attentionThanks for your attention