The BMW-Chandra Serendipitous Source Catalogue - R. P. Mignani (MSSL-UCL) P. Romano, S. Campana, A. Moretti, R. Panzera, G. Tagliaferri (INAF)

The BMW-Chandra
Serendipitous Source Catalogue
                  R. P. Mignani (MSSL-UCL)
P. Romano, S. Campana, A. Moretti, R. Panzera, G. Tagliaferri (INAF),
                        M. Mottini (ESO)

                 New Results in X-ray Astronomy, Leicester, July 2008

The Data Sample
•    Selected ACIS-I observations only
    FOV          : 16’x16’
    Spatial res. : 0.5”/px
    Spectral res.: E/ E ~ 20-50 over 0.2-10 keV
    Timing res. : 3ms
•    Exposure time >10 ks
•    Available by March 2003 (≈ first 3 yrs)

•    Field selection: we filtered out fields
      – Dominated by extended sources
      – Pointed to planets or SNR
      – With very bright sources
•    147 fields in total

•    11 fields discarded because pointings affected by instrument/spacecraft
     anomalies (spacecraft wobbling, solar flares, anomalous instrument bkg)
•    136 “good” fields left
•    Sky coverage ~ 8 deg2

High Latitude
Field Statistics

                   Low Latitude

The BMW Pipeline
• Data retrieved from the Chandra Data Archive

• Data reduced using the CIAO software

• Dedicated data reduction pipeline implemented
  @ Brera Astronomical Observatory (Milan)

• Reduced data  Source Detection Algorithm (SDA) based on Wavelet
  Transform (WT), originally developed @ OAB (Lazzati et al. 1999; Campana
  et al. 1999), hence Brera Multi-Wavelet (BMW) algorithm

• Already applied for the BMW-ROSAT catalogue (Panzera et al. 2003)

• Visual inspection of problematic cases and source screening

Source Extraction and screening

                 XTE J1723-376

Eta Carinae

Centaurus X-3

The BMW-Chandra Catalogue
•   A total of 21325 sources detected in the whole ACIS-I dataset

•   ~ 17000 single sources after X-matching multiple source detections
•   No merging in the catalogue (on purpose! e.g., to allow for variability)

•   16758 serendipitous sources (i.e., in addition to pointed targets)

•   Source catalogue contains
     – Positions (~ 0.5”, nominal Chandra aspect solution accuracy)
     – Count rates, Counts, Fluxes(*) in the
        • Soft (0.5-2.0 keV)       (*)
                                       Normalized
                                        ormalized to a power law with =2 and
                                    corrected minimum and maximum galactic absorption
        • Hard (2.0-7.0 KeV)
        • Total (0.5-7.0 keV)
     – HRs
     – Source extension
     – Multi- X-correlation information
     – Plus much more additional information (141 columns !)
•   Romano, Campana, Mignani, et al., 2008, A&A, in press

Source Statistics

      0.45”
                     4’

      soft

              hard

Multi- Cross-Correlations
• Cross correlations performed with optical-to-radio catalogues

    – GSC2: Lasker et al., 2008, AJ, in press
    All-Sky, Bj ~ 22.5, F ~ 22, N ~ 19.5, V ~14-19.5
    – 2MASS: Skrutskie et al., 2006, AJ, 131,1163
    All-Sky, J ~ 15.8, H ~ 15.1, Ks ~ 14.3
    – IRAS:      Beichmann et al., 1988
    All-Sky, ~ 0.4 Jy @ 12 m
    – FIRST: White et al., 1997, ApJ, 475, 479
    25%-Sky, ~ 1 mJy @ 20cm

• Single catalogue match via web through CDS and GSC2 database

• Master catalogue creation through off-line tools (closest match criteria)

• Only one source found in ALL catalogues (a bright radio/IR galaxy)

• Identification of possible candidate counterparts (position only)

Comparison with Champ
• Chandra Multiwavelength Project (Champ) - Kim et al., 2007, ApJ,659,29

• 149 Chandra ACIS-I/S fields, 6800 sources, over 10 deg2>9 x10-16 erg cm-2 s-1

• 210 sources matched in 3” radius (162 in 1” radius)

• Different instrument, datasets, fields selection wrt BMW-C

Summary
•   The BMW-Chandra is the largest catalogue of Chandra sources so far

•   16758 serendipitous sources

•   Limiting flux: 10-13 erg cm-2 s-1 (8 deg2) and 10-15 erg cm-2 s-1 (2 deg2)

•   Source flux (in 3 XEBs), extension, position (0.5”), multi- X-matches,+

•   Dedicated web service @ OAB (being set up now) with
     – Catalogue browser,
     – ACIS-I and DSS preview for each field, source overlay,
     – preview spectra and light curves,
     – catalogue info and other goodies, e.g. SIMBAD link, ++

•   Catalogue also available via CDS

Scientific exploitation of the BMW-C
•   Reference for follow-up observations. Synergy with 2XMMp, SWIFT/XRT,
    and BAT catalogues (under construction)

•   Source SED from radio to X-rays

•   In-depth analysis of brighter sources (variability, periodicity, spectroscopy)

•   Search for clusters of galaxies from source extension (in progress)

•   Search for transient/bursting sources

•   Source identification based on multi- X-correlations (Fx/Fopt, colors)

•   “Blank field” sources (e.g. BL Lacs, Type-2 quasars, high-z clusters, INSs)

A case of “Blank field” Sources
•   Radio-silent Isolated Neutron Stars (INSs)

•   Most of them discovered serendipitously in X-rays

•   Their emission properties set them apart from radio-pulsars

       transients                   bursters

•   How to find them? Apart from X-ray sources in SNRs no obvious targets

•   In first place, INS candidates can be singled out by their extreme FX/Fopt

•   Analysis of high FX/Fopt unidentified BMW-C sources (in progress)

Future prospects
 • BMW-Chandra 1.0 to be released soon

 • Plan: BMW-C will expand on a regular base to include other already
   public Chandra data and new ones as soon as they become public

 • Next goal (2009): BMW-C mid-term release (first Chandra 5 years)

 • Further goal (2010): BMW-C full release (first 10 years)

 • Release updates foreseen (if resources permit):
    re-processing with newer versions of CIAO
    coordinates correction via bore sight
    variability flags
    improved source screening
    X-ray source classification

 • BMW-ROSAT (2003)… BMW-Chandra (2008) …. BMW-?