The XXL Survey VI. The 1000 brightest X-ray point sources
S. Fotopoulou
(1)
,
F. Pacaud
(2, 3)
,
S. Paltani
(4)
,
P. Ranalli
(5, 6)
,
M. E. Ramos-Ceja
,
L. Faccioli
(7)
,
M. Plionis
(6)
,
C. Adami
(8)
,
A. Bongiorno
(9)
,
M. Brusa
(10, 11)
,
L. Chiappetti
(12)
,
S. Desai
,
A. Elyiv
(13)
,
C. Lidman
(14)
,
O. Melnyk
(15, 13)
,
M. Pierre
(16)
,
E. Piconcelli
(17)
,
C. Vignali
(18)
,
S. Alis
,
F. Ardila
,
S. Arnouts
(19)
,
I. Baldry
,
M. Bremer
(14)
,
D. Eckert
(20, 21)
,
L. Guennou
(8)
,
C. Horellou
(22)
,
A. Iovino
(14)
,
E. Koulouridis
(6, 23)
,
J. Liske
,
S. Maurogordato
(24)
,
F. Menanteau
,
J. J. Mohr
(25, 26, 27)
,
M. Owers
,
B. Poggianti
,
E. Pompei
,
T. Sadibekova
(23)
,
A. Stanford
,
R. Tuffs
,
J. Willis
(28)
1
Aristotle University of Thessaloniki
2 AlfA - Argelander-Institut für Astronomie
3 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 ISDC Data Centre for Astrophysics
5 Lund Observatory
6 ISARS/NOA - Institute for Space Applications and Remote Sensing
7 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
8 LAM - Laboratoire d'Astrophysique de Marseille
9 GATECH - College of Computing
10 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
11 OABO - INAF - Osservatorio Astronomico di Bologna
12 INAF- Milano
13 Institut d'Astrophysique et de Géophysique [Liège]
14 AUTRES
15 Astronomical Observatory of Kiev
16 UR EABX - Ecosystèmes aquatiques et changements globaux
17 OAR - INAF - Osservatorio Astronomico di Roma
18 INAF - Istituto Nazionale di Astrofisica
19 CFHT - Canada-France-Hawaii Telescope Corporation
20 UNIGE - Université de Genève = University of Geneva
21 INAF-IASF Milano
22 Department of Earth and Space Sciences [Göteborg]
23 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
24 LAGRANGE - Joseph Louis LAGRANGE
25 Excellence Cluster Universe
26 MPE - Max-Planck-Institut für Extraterrestrische Physik
27 LMU - Ludwig Maximilian University [Munich] = Ludwig Maximilians Universität München
28 JPL - Jet Propulsion Laboratory
2 AlfA - Argelander-Institut für Astronomie
3 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 ISDC Data Centre for Astrophysics
5 Lund Observatory
6 ISARS/NOA - Institute for Space Applications and Remote Sensing
7 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
8 LAM - Laboratoire d'Astrophysique de Marseille
9 GATECH - College of Computing
10 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
11 OABO - INAF - Osservatorio Astronomico di Bologna
12 INAF- Milano
13 Institut d'Astrophysique et de Géophysique [Liège]
14 AUTRES
15 Astronomical Observatory of Kiev
16 UR EABX - Ecosystèmes aquatiques et changements globaux
17 OAR - INAF - Osservatorio Astronomico di Roma
18 INAF - Istituto Nazionale di Astrofisica
19 CFHT - Canada-France-Hawaii Telescope Corporation
20 UNIGE - Université de Genève = University of Geneva
21 INAF-IASF Milano
22 Department of Earth and Space Sciences [Göteborg]
23 AIM (UMR7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
24 LAGRANGE - Joseph Louis LAGRANGE
25 Excellence Cluster Universe
26 MPE - Max-Planck-Institut für Extraterrestrische Physik
27 LMU - Ludwig Maximilian University [Munich] = Ludwig Maximilians Universität München
28 JPL - Jet Propulsion Laboratory
F. Pacaud
- Fonction : Auteur
- PersonId : 755664
- ORCID : 0000-0002-6622-4555
- IdRef : 134265130
S. Paltani
- Fonction : Auteur
- PersonId : 755532
- ORCID : 0000-0002-8108-9179
M. E. Ramos-Ceja
- Fonction : Auteur
S. Desai
- Fonction : Auteur
O. Melnyk
- Fonction : Auteur
- PersonId : 965981
M. Pierre
- Fonction : Auteur
- PersonId : 177664
- IdHAL : mmm-pierre
- ORCID : 0000-0002-9714-4929
C. Vignali
- Fonction : Auteur
- PersonId : 759209
- ORCID : 0000-0002-8853-9611
S. Alis
- Fonction : Auteur
F. Ardila
- Fonction : Auteur
I. Baldry
- Fonction : Auteur
C. Horellou
- Fonction : Auteur
- PersonId : 765479
- ORCID : 0000-0002-3533-8584
E. Koulouridis
- Fonction : Auteur
- PersonId : 776827
- ORCID : 0000-0002-9423-3723
J. Liske
- Fonction : Auteur
S. Maurogordato
- Fonction : Auteur
- PersonId : 178924
- IdHAL : sophie-maurogordato
- ORCID : 0000-0002-5477-8454
- IdRef : 033990018
F. Menanteau
- Fonction : Auteur
M. Owers
- Fonction : Auteur
B. Poggianti
- Fonction : Auteur
E. Pompei
- Fonction : Auteur
A. Stanford
- Fonction : Auteur
R. Tuffs
- Fonction : Auteur
Résumé
Context. X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). Usually, a combination of deep and wide surveys is necessary to create a complete picture of the population. Deep X-ray surveys provide the faint population at high redshift, while wide surveys provide the rare bright sources. Nevertheless, very wide area surveys often lack the ancillary information available for modern deep surveys. The XXL survey spans two fields of a combined 50 deg(2) observed for more than 6Ms with XMM-Newton, occupying the parameter space that lies between deep surveys and very wide area surveys; at the same time it benefits from a wealth of ancillary data. Aims. This paper marks the first release of the XXL point source catalogue including four optical photometry bands and redshift estimates. Our sample is selected in the 2-10 keV energy band with the goal of providing a sizable sample useful for AGN studies. The limiting flux is F2-10 keV = 4.8 x 10(14) erg s(-1) cm(-2). Methods. We use both public and proprietary data sets to identify the counterparts of the X-ray point-like sources by means of a likelihood ratio test. We improve upon the photometric redshift determination for AGN by applying a Random Forest classification trained to identify for each object the optimal photometric redshift category (passive, star forming, starburst, AGN, quasi-stellar objects (QSO)). Additionally, we assign a probability to each source that indicates whether it might be a star or an outlier. We apply Bayesian analysis to model the X-ray spectra assuming a power-law model with the presence of an absorbing medium. Results. We find that the average unabsorbed photon index is \textlessGamma \textgreater = 1.85 +/- 0.40 while the average hydrogen column density is log \textless N-H \textgreater i = 21.07 +/- 1.2 cm(-2). We find no trend of Gamma or N-H with redshift and a fraction of 26% absorbed sources (log N-H \textgreater 22) consistent with the literature on bright sources (log L-x \textgreater 44). The counterpart identification rate reaches 96.7% for sources in the northern field, 97.7% for the southern field, and 97.2% in total. The photometric redshift accuracy is 0.095 for the full XMM-XXL with 28% catastrophic outliers estimated on a sample of 339 sources. Conclusions. We show that the XXL-1000-AGN sample number counts extended the number counts of the COSMOS survey to higher fluxes and are fully consistent with the Euclidean expectation. We constrain the intrinsic luminosity function of AGN in the 2-10 keV energy band where the unabsorbed X-ray flux is estimated from the X-ray spectral fit up to z = 3. Finally, we demonstrate the presence of a supercluster size structure at redshift 0.14, identified by means of percolation analysis of the XXL-1000-AGN sample. The XXL survey, reaching a medium flux limit and covering a wide area, is a stepping stone between current deep fields and planned wide area surveys.