J/A+A/608/A39 X-ATLAS X-ray sources photometric redshifts (Mountrichas+, 2017)
Estimating photometric redshifts for X-ray sources in the X-ATLAS field,
using machine-learning techniques.
Mountrichas G., Corral A., Masoura V.A., Georgantopoulos I., Ruiz A.,
Georgakakis A., Carrera F.J., Fotopoulou S.
<Astron. Astrophys. 608, A39 (2017)>
=2017A&A...608A..39M 2017A&A...608A..39M (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Redshifts
Keywords: X-rays: general - galaxies: active - catalogs -
techniques: photometric
Abstract:
We present photometric redshifts for 1,031 X-ray sources in the
X-ATLAS field using the machine-learning technique TPZ. X-ATLAS covers
7.1 deg2 observed with XMM-Newton within the Science Demonstration
Phase (SDP) of the H-ATLAS field, making it one of the largest
contiguous areas of the sky with both XMM-Newton and Herschel
coverage. All of the sources have available SDSS photometry, while 810
additionally have mid-IR and/or near-IR photometry. A spectroscopic
sample of 5,157 sources primarily in the XMM/XXL field, but also from
several X-ray surveys and the SDSS DR13 redshift catalogue, was used
to train the algorithm. Our analysis reveals that the algorithm
performs best when the sources are split, based on their optical
morphology, into point-like and extended sources. Optical photometry
alone is not enough to estimate accurate photometric redshifts, but
the results greatly improve when at least mid-IR photometry is added
in the training process. In particular, our measurements show that the
estimated photometric redshifts for the X-ray sources of the training
sample have a normalized absolute median deviation, nmadh0.06, and a
percentage of outliers, η=10-14%, depending upon whether the sources
are extended or point like. Our final catalogue contains photometric
redshifts for 933 out of the 1,031 X-ray sources with a median
redshift of 0.9.
Description:
The Herschel Terahertz Large Area survey (H-ATLAS) is the largest Open
Time Key Project carried out with the Herschel Space Observatory
(Eales et al., 2010PASP..122..499E 2010PASP..122..499E), covering an area of 550 deg2 in
five far-infrared and sub-millimeter (submm) bands (100, 160, 250,
350, and 500um). 16 deg2 have been presented in the Science
Demonstration Phase (SDP) catalogue (Rigby et al., 2011, Cat.
J/MNRAS/415/2336) and lie within one of the regions observed by the
Galaxy And Mass Assembly (GAMA) survey (Driver et al. 2011, Cat.
J/MNRAS/413/971; Baldry et al. 2010MNRAS.404...86B 2010MNRAS.404...86B). XMM-Newton
observed 7.1 deg2 with a total exposure time of 336ks (in the MOS1
camera) within the H-ATLAS SDP area, making the XMM-ATLAS one of the
largest contiguous areas of the sky with both XMM-Newton and Herschel
coverage. The catalogue contains 1816 unique sources (Ranalli et al.
2015, Cat. J/A+A/577/A121).
To obtain optical, mid-IR, and far-IR photometry for the XMM-ATLAS
sources, we cross-matched the X-ray catalogue with the SDSS-DR13
(Albareti et al., 2015, Cat. J/MNRAS/452/4153), the WISE (Wright et
al. 2010AJ....140.1868W 2010AJ....140.1868W, See Cat. II/311 and II/328), and the
VISTA-VIKING catalogues (Emerson et al. 2006, Msngr, 126, 41; Dalton
et al. 2006, SPIE, 6269, see Cat. II/343/) with the ARCHES
cross-correlation tool xmatch, which symmetrically matches an
arbitrary number of catalogues providing a Bayesian Probability of
association or non-association (Pineau, 2016, eprint arXiv:1609.03457).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
photoz.dat 974 1031 Photometric redshifts
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See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
II/343 : VIKING catalogue data release 2 (Edge+, 2016)
J/MNRAS/452/4153 : SDSS DR12 QSOs [OIII] doublet (Albareti+, 2015)
J/A+A/577/A121 : The XMM-ATLAS catalogues (Ranalli+, 2015)
http://skyserver.sdss.org/dr13/ : SDSS DR13 Home Page
Byte-by-byte Description of file: photoz.dat
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Bytes Format Units Label Explanations
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1- 18 F18.14 deg RAdeg XMM right ascension (J2000)
20- 41 E22.19 deg DEdeg XMM declination (J2000)
43- 60 F18.14 deg RASdeg SDSS DR13 right ascension (J2000)
62- 83 F22.19 deg DESdeg SDSS DR13 declination (J2000)
85 I1 --- Class [0/2] Classification (1)
87- 88 I2 --- Bands [5/10] Available photometric bands (2)
90- 92 F3.1 --- zsp [0] Spectroscopic redshift
94- 99 F6.4 --- zph [0/3.45] Photometric redshift, mode (3)
101-106 F6.4 --- Average photometric redshift
108-113 F6.4 --- zphconf Redshift confidence level, mode
115-120 F6.4 --- Average redshift confidence level
122-127 F6.4 --- e_zph rms uncertainty on zph, mode
129-134 F6.4 --- e_ rms uncertainty on
136-146 E11.9 --- PDF1 Probability density function bin (step=0.05)
148-158 E11.9 --- PDF2 Probability density function bin (step=0.05)
160-170 E11.9 --- PDF3 Probability density function bin (step=0.05)
172-182 E11.9 --- PDF4 Probability density function bin (step=0.05)
184-194 E11.9 --- PDF5 Probability density function bin (step=0.05)
196-206 E11.9 --- PDF6 Probability density function bin (step=0.05)
208-218 E11.9 --- PDF7 Probability density function bin (step=0.05)
220-230 E11.9 --- PDF8 Probability density function bin (step=0.05)
232-242 E11.9 --- PDF9 Probability density function bin (step=0.05)
244-254 E11.9 --- PDF10 Probability density function bin (step=0.05)
256-266 E11.9 --- PDF11 Probability density function bin (step=0.05)
268-278 E11.9 --- PDF12 Probability density function bin (step=0.05)
280-290 E11.9 --- PDF13 Probability density function bin (step=0.05)
292-302 E11.9 --- PDF14 Probability density function bin (step=0.05)
304-314 E11.9 --- PDF15 Probability density function bin (step=0.05)
316-326 E11.9 --- PDF16 Probability density function bin (step=0.05)
328-338 E11.9 --- PDF17 Probability density function bin (step=0.05)
340-350 E11.9 --- PDF18 Probability density function bin (step=0.05)
352-362 E11.9 --- PDF19 Probability density function bin (step=0.05)
364-374 E11.9 --- PDF20 Probability density function bin (step=0.05)
376-386 E11.9 --- PDF21 Probability density function bin (step=0.05)
388-398 E11.9 --- PDF22 Probability density function bin (step=0.05)
400-410 E11.9 --- PDF23 Probability density function bin (step=0.05)
412-422 E11.9 --- PDF24 Probability density function bin (step=0.05)
424-434 E11.9 --- PDF25 Probability density function bin (step=0.05)
436-446 E11.9 --- PDF26 Probability density function bin (step=0.05)
448-458 E11.9 --- PDF27 Probability density function bin (step=0.05)
460-470 E11.9 --- PDF28 Probability density function bin (step=0.05)
472-482 E11.9 --- PDF29 Probability density function bin (step=0.05)
484-494 E11.9 --- PDF30 Probability density function bin (step=0.05)
496-506 E11.9 --- PDF31 Probability density function bin (step=0.05)
508-518 E11.9 --- PDF32 Probability density function bin (step=0.05)
520-530 E11.9 --- PDF33 Probability density function bin (step=0.05)
532-542 E11.9 --- PDF34 Probability density function bin (step=0.05)
544-554 E11.9 --- PDF35 Probability density function bin (step=0.05)
556-566 E11.9 --- PDF36 Probability density function bin (step=0.05)
568-578 E11.9 --- PDF37 Probability density function bin (step=0.05)
580-590 E11.9 --- PDF38 Probability density function bin (step=0.05)
592-602 E11.9 --- PDF39 Probability density function bin (step=0.05)
604-614 E11.9 --- PDF40 Probability density function bin (step=0.05)
616-626 E11.9 --- PDF41 Probability density function bin (step=0.05)
628-638 E11.9 --- PDF42 Probability density function bin (step=0.05)
640-650 E11.9 --- PDF43 Probability density function bin (step=0.05)
652-662 E11.9 --- PDF44 Probability density function bin (step=0.05)
664-674 E11.9 --- PDF45 Probability density function bin (step=0.05)
676-686 E11.9 --- PDF46 Probability density function bin (step=0.05)
688-698 E11.9 --- PDF47 Probability density function bin (step=0.05)
700-710 E11.9 --- PDF48 Probability density function bin (step=0.05)
712-722 E11.9 --- PDF49 Probability density function bin (step=0.05)
724-734 E11.9 --- PDF50 Probability density function bin (step=0.05)
736-746 E11.9 --- PDF51 Probability density function bin (step=0.05)
748-758 E11.9 --- PDF52 Probability density function bin (step=0.05)
760-770 E11.9 --- PDF53 Probability density function bin (step=0.05)
772-782 E11.9 --- PDF54 Probability density function bin (step=0.05)
784-794 E11.9 --- PDF55 Probability density function bin (step=0.05)
796-806 E11.9 --- PDF56 Probability density function bin (step=0.05)
808-818 E11.9 --- PDF57 Probability density function bin (step=0.05)
820-830 E11.9 --- PDF58 Probability density function bin (step=0.05)
832-842 E11.9 --- PDF59 Probability density function bin (step=0.05)
844-854 E11.9 --- PDF60 Probability density function bin (step=0.05)
856-866 E11.9 --- PDF61 Probability density function bin (step=0.05)
868-878 E11.9 --- PDF62 Probability density function bin (step=0.05)
880-890 E11.9 --- PDF63 Probability density function bin (step=0.05)
892-902 E11.9 --- PDF64 Probability density function bin (step=0.05)
904-914 E11.9 --- PDF65 Probability density function bin (step=0.05)
916-926 E11.9 --- PDF66 Probability density function bin (step=0.05)
928-938 E11.9 --- PDF67 Probability density function bin (step=0.05)
940-950 E11.9 --- PDF68 Probability density function bin (step=0.05)
952-962 E11.9 --- PDF69 Probability density function bin (step=0.05)
964-974 E11.9 --- PDF70 Probability density function bin (step=0.05)
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Note (1): Classification as follows:
1 = pointlike
0 = extended
2 = extended treated as pointlike
extended sources that were assigned photoz>1 had their redshift re-estimated,
using the second time pointlike, training samples.
Note (2): Available photometric bands as follows:
5 = SDSS
7 = SDSS+WISE
8 = SDSS+NIR
10 = SDSS+WISE+NIR
Note (3): a value of photoz=0.001 means TPZ failed to estimate a
photometric redshift.
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Acknowledgements:
Georgios Mountrichas, gmountrichas(at)gmail.com
(End) Patricia Vannier [CDS] 17-Oct-2017