J/A+A/469/1211 XMM-Newton survey of SA 57 (Trevese+, 2007)
An X-ray Survey in SA 57 with XMM-Newton.
Trevese D., Vagnetti F., Puccetti S., Fiore F., Tomei M., Bershady M.A.
<Astron. Astrophys. 469, 1211 (2007)>
=2007A&A...469.1211T 2007A&A...469.1211T
ADC_Keywords: Surveys ; X-ray sources
Keywords: surveys - galaxies: active - galaxies: quasars: general -
X-rays: galaxies
Abstract:
The maximum number density of Active Galactic Nuclei (AGNs), as
deduced from X-ray studies, occurs at z≥1, with lower luminosity
objects peaking at smaller redshifts. Optical studies lead to a
different evolutionary behaviour, with a number density peaking at z∼2
independently of the intrinsic luminosity, but this result is limited
to active nuclei brighter than the host galaxy. A selection based on
optical variability can detect low luminosity AGNs (LLAGNs), where the
host galaxy light prevents the identification by non-stellar colours.
We want to collect X-ray data in a field where it exists an
optically-selected sample of "variable galaxies", i.e. variable
objects with diffuse appearance, to investigate the X-ray and optical
properties of the population of AGNs, particularly of low luminosity
ones, where the host galaxy is visible. We observed a field of
∼0.2°2 in the Selected Area 57, for 67ks with XMM-Newton.
We detected X-ray sources, and we correlated the list with a
photographic survey of SA 57, complete to BJ∼23 and with available
spectroscopic data.
We obtained a catalogue of 140 X-ray sources to limiting fluxes
5x10-16, 2x10-15erg/cm2/s in the 0.5-2keV and 2-10keV
respectively, 98 of which are identified in the optical bands. The
X-ray detection of part of the variability-selected candidates
confirms their AGN nature. Diffuse variable objects populate the low
luminosity side of the sample. Only 25/44 optically-selected QSOs are
detected in X-rays. 15% of all QSOs in the field have X/O<0.1.
Description:
We have obtained a 67ks XMM-Newton pointing of the SA57 region
centered at 13:08:28+29:23:07 (J2000). The X-ray observations were
performed on January 2005. Source detection was performed on co-added
PN+MOS1+MOS2 images accumulated in four energy bands: 0.5-10keV,
0.5-2keV, 2-10keV, 5-10keV. The source detections and the X-ray
photometry were performed by using the PWXDetect code (Pillitteri et
al. 2006) based on wavelet transform of the count rate image We
adopted a threshold on the significance level corresponding to a
probability of 2*10-5 that a local maximum is generated by a Poisson
fluctuation of the background counts. The limiting fluxes in the four
bands are approximately: 10-15, 5*10-16, 2*10-15,
10-14erg/cm2/s, respectively. The result of this selection is a
sample of 140 sources, detected in at least one band.
A photographic survey of SA57 was conducted with the prime focus
camera at Mayall 4 m telescope at Kitt Peak National Observatory
(KPNO) from 1974 to 1989. A photometric catalogue of 8146 objects in
U, BJ, F and N bands in a field of ∼0.3deg2, complete to BJ∼23 was
used for optical identifications of the X-ray detected sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 140 The source catalog
table3.dat 60 112 Optical identifications
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [SA57X]
7- 9 I3 --- SA57X catalog number
11 A1 --- f_SA57X [cd] Flag on source detection (1)
13- 14 I2 h RAh X-ray right ascension (J2000)
16- 17 I2 min RAm X-ray right ascension (J2000)
19- 23 F5.2 s RAs X-ray right ascension (J2000)
25 A1 --- DE- X-ray declination sign (J2000)
26- 27 I2 deg DEd X-ray declination (J2000)
29- 30 I2 arcmin DEm X-ray declination (J2000)
32- 35 F4.1 arcsec DEs X-ray declination (J2000)
37- 41 F5.2 10-17W/m2 Fxt 0.5-10keV flux (10-14erg/cm2/s)
43 A1 --- f_Fxt [bu] Note on 0.5-10keV detection (2)
45- 48 F4.2 10-17W/m2 Fxs 0.5-2keV flux (10-14erg/cm2/s)
50 A1 --- f_Fxs [bu] Note on 0.5-2keV detection (2)
52- 55 F4.2 10-17W/m2 Fxh 2-10keV flux (10-14erg/cm2/s)
57 A1 --- f_Fxh [bu] Note on 2-10keV detection (2)
59 A1 --- IDr rank of optical identification (G1)
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Note (1): note on source detection, as follows:
c = at the same position an extended source is detected,
corresponding to the galaxy cluster ZwCl 1305.4+2941,
not considered in the present analysis
d = this source is only detected in the 5-10 keV band, with
fx=3.48*10-14erg/cm2/s
Note (2): note on fluxes, as follows:
b = object not detected in this band, with flux computed from the
other bands
u = upper limit
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Byte-by-byte description of file: table3.dat
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bytes format units label explanations
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1- 3 I3 --- SA57X SA57X number, as in table1.
5 A1 --- IDr rank of optical identification (1)
8- 12 I5 --- Nser kpno survey of SA 57 optical catalog number (1)
13 A1 --- n_Nser [d] d: Number in NGPFG Catalogue
(Infante et al., 1995, Cat. VII/208,
NGPFG NNNNN in Simbad)
15- 16 I2 h RAh right ascension (J2000)
18- 19 I2 min RAm right ascension (J2000)
21- 25 F5.2 s RAs right ascension (J2000)
27 A1 --- DE- declination sign (J2000)
28- 29 I2 deg DEd declination (J2000)
31- 32 I2 arcmin DEm declination (J2000)
34- 37 F4.1 arcsec DEs declination (J2000)
39- 43 F5.2 mag Bjmag KPNO Bj magnitude
45- 49 F5.2 mag Fmag ? KPNO F magnitude
51- 55 F5.3 --- z ? redshift
57- 59 A3 --- Class classification (2)
60 A1 --- n_Class [e] e: Candidates or confirmed AGNs selected
through variability and not previously
selected by other methods
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Note (1): from Koo 1986apj...311..651K 1986apj...311..651K and Kron 1980ApJS...43..305K 1980ApJS...43..305K,
[K80] SA 57 nnnnn in Simbad.
Note (2): Classification as follows:
Q = quasar
G = galaxy
BTK = extended variable object from Bershady et al. (1998ApJ...496..103B 1998ApJ...496..103B)
RG = radio galaxy
[Q] = point-like quasar candidate
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Global notes:
Note (G1): rank of optical identification, as follows:
U = unidentified
I = identified
M = marginal identification
A = ambiguous identification
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Acknowledgements:
Dario Trevese, dario.trevese(at)roma1.infn.it
History:
* 10-May-2007: original version (only table2, from author)
* 13-Feb-2008: table3 added (from electronic version)
(End) Patricia Vannier [CDS] 10-May-2007