Statistical properties of a sample of serendipitous X-ray ... · Swift XRT serendipitous sources in...
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Statistical properties of a sampleof serendipitous X-ray sources in
deep Swift GRB pointingsPaolo Giommi
ASI
Swift observationsarchive content as of June 2008
• 14,500 observations• 3,380 distinct pointings• ~300 sq deg of sky (< 1%)
Unique database of optical/UV X-ray simultaneous data
More than 300 GRB detected and followed up for several days/weeks with the X-ray Telescope
Swift XRT serendipitous sources in GRBs pointigs :the “perfect” serendipitous survey
Most X-ray sourcesare radio quiet QSOsOnly ~1 blazar/fieldexpected withradio flux > 10 mJy!
Energy spectral slope
235 deep (104-106 seconds) GRB exposures analyzed
~7,600 sources detected with off-axis < 10 arcminPositional uncertainty 3-5 arcsecs.
160 fields are at |bII| > 20 : ~5,600 sources156 radio/X-ray matches (blazar candidates)
Swift XRT serendipitous survey in GRB deep fields
The sample for this exercise5 fields in areas of the sky
covered by the Sloan Digital SkySurvey (SDSS)
240 X-ray sources
GRB 050416AGRB 050416BGRB 060908GRB 060904AGRB 050802
The sky coverage
www.asdc.asi.it/urbinoschool
Multiple Optical Counterparts(Likelihood Ratio)
- Photometric Redshifts calculation
55
X-ray/radio associations match 107 SDSS-DR6
objects(10 spectra)
Optical counterpartsOptical counterpartsin the SDSS-DR6in the SDSS-DR6
Turriziani et al. 2008, in preparation
Photometric redshiftdistributions