J/A+A/469/27 XMM serendipitous survey AXIS X-ray source counts (Carrera+, 2007)
The XMM-Newton serendipitous survey.
III. The AXIS X-ray source counts and angular clustering.
Carrera F.J., Ebrer J., Mateos S., Ceballos M.T., Corral A., Barcons X.,
Page M.J., Rosen S.R., Watson M.G., Tedds J.A., Della Ceca R., Maccacaro T.,
Brunner H., Freyberg M., Lamer G., Bauer F.E., Ueda Y.
<Astron. Astrophys. 469, 27 (2007)>
=2007A&A...469...27C 2007A&A...469...27C (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; X-ray sources
Keywords: surveys - X-rays: general -
cosmology: large-scale structure of the Universe
Abstract:
Recent results have revised upwards the total X-ray background (XRB)
intensity below 10keV, therefore an accurate determination of the
source counts is needed. There are also contradictory results on the
clustering of X-ray selected sources.
We have studied the X-ray source counts in four energy bands: soft
(0.5-2keV), hard (2-10keV), XID (0.5-4.5keV) and ultra-hard
(4.5-7.5keV) in order to evaluate the contribution of sources at
different fluxes to the X-ray background. We have also studied the
angular clustering of X-ray sources in those bands.
AXIS (An XMM International Survey) is a survey of 36 high Galactic
latitude XMM observations covering 4.8deg2 in the Northern sky and
containing 1433 serendipitous X-ray sources detected with 5-sigma
significance. This survey has similar depth to the XMM catalogues and
therefore serves as a pathfinder to explore their possibilities. We
have combined this survey with shallower and deeper surveys, and
fitted the source counts with a Maximum Likelihood technique. Using
only AXIS sources we have studied the angular correlation using a
novel robust technique.
Our source counts results are compatible with most previous samples in
the soft, XID, ultra-hard and hard bands. We have improved on previous
results in the hard band. The fractions of the XRB resolved in the
surveys used in this work are 87%, 85%, 60% and 25% in the soft, hard,
XID and ultra-hard bands, respectively. Extrapolation of our source
counts to zero flux is not sufficient to saturate the XRB intensity.
Only galaxies and/or absorbed AGN could contribute the remaining
unresolved XRB intensity. Our results are compatible, within the
errors, with recent revisions of the XRB intensity in the soft and
hard bands. The maximum fractional contribution to the XRB comes from
fluxes within about a decade of the break in the source counts
(∼10-14cgs), reaching ∼50% of the total in the soft and hard bands.
Angular clustering (widely distributed over the sky and not confined
to a few deep fields) is detected at 99-99.9% significance in the soft
and XID bands, with no detection in the hard and ultra-hard band
(probably due to the smaller number of sources). We cannot confirm the
detection of significantly stronger clustering in the hard-spectrum
hard sources.
Medium depth surveys such as AXIS are essential to determine the
evolution of the X-ray emission in the Universe below 10keV.
Description:
We include here the basic data for the 36 XMM-Newton fields and the
2560 X-ray sources in that paper:
- XMM-Newton pn count-rates in four bands (band 2 0.5-2keV,
band 3 2-4.5keV, band 4 4.5-7.5keV, band 5 7.5-12keV)
- spectral photon indices in the 0.5-4.5keV band, in the 2-10keV
band and in the 0.5-10keV band
- fluxes in the soft (0.5-2keV), hard (2-10keV), XID (0.5-4.5keV),
ultra-hard (4.5-7.5keV) and "total" (0.5-10keV) bands
- flags to describe to which of the samples discussed in that paper
(soft, hard, XID or ultra-hard) each source belongs to
There is no spectral or flux information on the sources not belonging
to any of the samples, the count-rates are given for completeness
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 135 36 Basic XMM-Newton field data
table23.dat 352 2560 Counts, spectral information and fluxes of the
sources (tables 2 and 3)
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See also:
IX/37 : XMM-Newton Serendipitous Source Catalogue, 1XMM (XMM-SSC, 2003)
J/A+A/428/383 : XMM-Newton Bright Serendipitous Survey (Della Ceca+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Target Target of the XMM-Newton observation
16- 30 A15 --- OBSID XMM-Newton revolution/Observation ID
32- 33 I2 h RAh Right ascension of the field center (J2000)
35- 36 I2 min RAm Right ascension of the field center (J2000)
38- 42 F5.2 s RAs Right ascension of the field center (J2000)
44 A1 --- DE- Declination sign of the field center (J2000)
45- 46 I2 deg DEd Declination of the field center (J2000)
48- 49 I2 arcmin DEm Declination of the field center (J2000)
51- 55 F5.2 arcsec DEs Declination of the field center (J2000)
57- 63 F7.1 s ExpTime XMM-Newton pn exposure time
65- 70 A6 --- Filter XMM-Newton pn filter name
72- 76 F5.2 10+20cm-2 NHGal Galactic column density
78- 79 I2 h RAt.h ?=- Right ascension of the target exclusion
81- 82 I2 min RAt.m ?=- Right ascension of the target exclusion
84- 87 F4.1 s RAt.s ?=- Right ascension of the target exclusion
89 A1 --- DEt.- Declination sign of the target exclusion
90- 91 I2 deg DEt.d ?=- Declination of the target exclusion
93- 94 I2 arcmin DEt.m ?=- Declination of the target exclusion
96-100 F5.2 arcsec DEt.s ?=- Declination of the target exclusion
102-104 I3 arcsec xr.t Exclusion radius around the target
106-107 I2 arcsec xw Width excluded around the OOOT events strip
109-110 I2 h RAa.h ?=- Right ascension of the additional exclusion
112-113 I2 min RAa.m ?=- Right ascension of the additional exclusion
115-118 F4.1 s RAa.s ?=- Right ascension of the additional exclusion
120 A1 --- DEa.- Declination sign of the additional exclusion
121-122 I2 deg DEa.d ?=- Declination of the additional exclusion
124-125 I2 arcmin DEa.m ?=- Declination of the additional exclusion
127-131 F5.2 arcsec DEa.s ?=- Declination of the additional exclusion
133-135 I3 arcsec xr.a Radius of the additional exclusion
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Byte-by-byte Description of file: table23.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [XMMU]
5- 19 A15 --- XMMU IAU name of the source, hhmmss.s+ddmmss
21- 30 F10.6 deg RAdeg Right Ascension J2000
32- 41 F10.6 deg DEdeg Declination J2000
43- 47 F5.2 arcsec ePos 90% uncertainty radius in position
49- 54 F6.4 ct/s CR2 Countrate in 0.5-2keV band
56- 61 F6.4 ct/s e_CR2 Uncertainty in that band
63- 71 F9.3 --- ML2 Likelihood of detection in that band
73- 78 F6.4 ct/s CR3 Countrate in 2-4.5keV band
80- 85 F6.4 ct/s e_CR3 Uncertainty in that band
87- 94 F8.3 --- ML3 Likelihood of detection in that band
96-101 F6.4 ct/s CR4 Countrate in 4.5-7.5keV band
103-108 F6.4 ct/s e_CR4 Uncertainty in that band
110-116 F7.3 --- ML4 Likelihood of detection in that band
118-123 F6.4 ct/s CR5 Countrate in 7.5-12keV band
125-130 F6.4 ct/s e_CR5 Uncertainty in that band
132-138 F7.3 --- ML5 Likelihood of detection in that band
140-145 F6.4 ct/s CRXID Countrate in 0.5-4.5keV band
147-152 F6.4 ct/s e_CRXID Uncertainty in that band
154-162 F9.3 --- MLXID Likelihood of detection in that band
164-170 F7.3 --- Gsoft ?=-99.000 Photon index in 0.5-4.5keV
172-178 F7.3 --- E_Gsoft ?=-99.000 Upper 1sigma uncertainty on GSoft
180-186 F7.3 --- e_Gsoft ?=-99.000 Lower 1sigma uncertainty on GSoft
188-197 E10.5 mW/m2 Fsoft ?=-.9900E+02 Flux in the 0.5-2keV band (Soft)
199-208 E10.5 mW/m2 e_Fsoft ?=0.0000E+00 1sigma uncertainty on FSoft
210-216 F7.3 --- Ghard ?=-99.000 Photon index in 2-12keV
218-224 F7.3 --- E_Ghard ?=-99.000 Upper 1sigma uncertainty on GHard
226-232 F7.3 --- e_Ghard ?=-99.000 Lower 1sigma uncertainty on GHard
234-243 E10.5 mW/m2 Fhard ?=-.9900E+02 Flux in the 2-10keV band (Hard)
245-254 E10.5 mW/m2 e_Fhard ?=0.0000E+00 1sigma uncertainty on FHard
256-265 E10.5 mW/m2 FXID ?=-.9900E+02 Flux in the 0.5-4.5keV band (XID)
267-276 E10.5 mW/m2 e_FXID ?=0.0000E+00 1sigma uncertainty on FXID
278-287 E10.5 mW/m2 FUH ?=-.9900E+02 Flux in the 4.5-7.5keV band (UH)
289-298 E10.5 mW/m2 e_FUH ?=0.0000E+00 1sigma uncertainty on FUH
300-306 F7.3 --- G0510 ?=-99.000 Photon index in 0.5-12keV
308-314 F7.3 --- E_G0510 ?=-99.000 Upper 1sigma uncertainty on G0510
316-322 F7.3 --- e_G0510 ?=-99.000 Lower 1sigma uncertainty on G0510
324-333 E10.4 mW/m2 F0510 ?=-.9900E+02 Flux in the 0.5-10keV band
335-344 E10.4 mW/m2 e_F0510 ?=0.0000E+00 1sigma uncertainty on F0510
346 I1 --- sS [0/1] 1 = belongs to the Soft sample
348 I1 --- sH [0/1] 1 = belongs to the Hard sample
350 I1 --- sX [0/1] 1 = belongs to the XID sample
352 I1 --- sU [0/1] 1 = belongs to the UH sample
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Acknowledgements:
Francisco J. Carrera, carreraf(at)ifca.unican.es
References:
Watson et al., Paper I 2001A&A...365L..51W 2001A&A...365L..51W
Barcons et al., Paper II 2002A&A...382..522B 2002A&A...382..522B
(End) Francisco J. Carrera [IFCA CSIC-UC, Spain], P. Vannier [CDS] 24-Apr-2007