Transcript Diapositiva 1

The VLA Survey of the
Chandra Deep Field South
X-ray Properties of Radio Sources
Shaji Vattakunnel - University of Trieste
Paolo Tozzi - Francesca Matteucci
AGN9 – Ferrara
25th May 2010
Outline
- D e e p R a d i o a n d X - ray S u r ve ys o f t h e
C h a n d ra D e e p F i e l d S o u t h
- X - ray p ro p e r t i e s o f R a d i o S o u rc e s
- T h e s u b - m J y ra d i o s o u rc e p o p u l at i o n
Deep Radio and X-ray Surveys
Flattening of the radio
counts below one mJy
Possibly due to Star
Forming Galaxies
VLA/Chandra Surveys
1Ms X-ray observation
Kellerman et al 2008
Mainieri et al 2008
Tozzi et al 2008
Padovani et al 2009
Flattening below 1 mJy
Kellerman et al. 2008
Radio and X-ray observations are efficient in identifying star formation vs
nuclear activity at high redshifts.
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 population
Analogous to results found by Gruppioni et al (1999) Prandoni et al (2009)
The Extended Chandra Deep Field South (E-CDFS)
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)
Radio image (1.4 GHz)
The Chandra Deep Field South (CDFS)
0.3 – 1 keV
1 – 2 keV
2 – 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
[0.3-7 keV]
X-ray color image of the 2Ms
(441 with redshifts)
derived from Luo et al. 2008
The Extended Chandra Deep Field South (E-CDFS)
4 pointings
250 ks
9 observations
32’ x 32’ image
sensitivity ~10-16 erg cm-2 s-1
753 sources
(Lehmer et al. 2005)
X-ray color image of the flanking field
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
2Ms/EVLA (2007)
observation
347
448
X-ray sources in the CDFS
266
1571
Radio sources in the ECDFS
89
227
Radio sources with an
X-ray counterpart
77%
95%
redshift available
Identification of X-Ray Counterparts
Positional match between X-ray and radio sources
Counterparts if the separation is less than 3σd , where:
σ2d = σ2x + σ2r
X-ray rms 0.3” < σx < 1.9”
Radio rms estimated at 0.2”
Optical
X-Ray
Radio
AGN / SFG discrimination
Luminosity from:
Sources with few counts
Sources with high counts
(full spectral analysis)
Total sources: 227
# of AGNs: 177
# of SFG candidates: 50
Discriminating AGNs:
- X-ray Luminosity
Lx > 1042 erg/s
- Radio Power
Pr > 1024.5 W/Hz
- column density
NH > 1021 cm-2
AGN / SFG discrimination
Low Lum AGNs
Absorbed AGNs
Star Forming Gal
Unabsorbed AGNs
Star Formation Rates
sources with 0.1 < z < 0.5
sources with 0.5 < z < 1.2
Condon (1992)
SFR =
L1.4GHz
28 M / yr
x
4.0 10
SFR = 1.6 x 10
The normalization is consistent with Ranalli (2003) SFR = 2.0 x 10
There is no evidence of evolution in redshift
-40
L2-10 keV M / yr
0 < z < 1.2
-40
L2-10 keV M / yr
Conclusions
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
X-ray stacking of the 1307 radio sources without a catalogued X-ray counterpart
Compute 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 attention