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+J/A+A/642/A150        Quasars as standard candles. III.           (Lusso+, 2020)
+================================================================================
+Quasars as standard candles.
+III. Validation of a new sample for cosmological studies.
+    Lusso E., Risaliti G., Nardini E., Bargiacchi G., Benetti M., Bisogni S.,
+    Capozziello S., Civano F., Eggleston L., Elvis M., Fabbiano G., Gilli R.,
+    Marconi A., Paolillo M., Piedipalumbo E., Salvestrini F., Signorini M.,
+    Vignali C.
+    <Astron. Astrophys. 642, A150 (2020)>
+    =2020A&A...642A.150L        (SIMBAD/NED BibCode)
+================================================================================
+ADC_Keywords: QSOs ; Active gal. nuclei ; Redshifts ; X-ray sources ;
+              Ultraviolet ; Optical ; Stars, distances
+Keywords: galaxies: active - quasars: general -
+          quasars: supermassive black holes - methods: statistical
+
+Abstract:
+    We present a new catalogue of ~2400 optically selected quasars with
+    spectroscopic redshifts and X-ray observations from either Chandra or
+    XMM-Newton. The sample can be used to investigate the non-linear
+    relation between the UV and X-ray luminosity of quasars, and to build
+    a Hubble diagram up to redshift z~7.5.
+
+    We selected sources that are neither reddened by dust in the
+    optical/UV nor obscured by gas in the X-rays, and whose X-ray fluxes
+    are free from flux-limit related biases. After checking for any
+    possible systematics, we confirm, in agreement with our previous
+    works, that (i) the X-ray to UV relation provides distance estimates
+    matching those from supernovae up to z~1.5, and (ii) its slope shows
+    no redshift evolution up to z~5. We provide a full description of the
+    methodology for testing cosmological models, further supporting a
+    trend whereby the Hubble diagram of quasars is well reproduced by the
+    standard flat LambdaCDM model up to z~1.5-2, but strong deviations
+    emerge at higher redshifts. Since we have minimized all non-negligible
+    systematic effects, and proven the stability of the Lx-Lo relation at
+    high redshifts, we conclude that an evolution of the expansion rate of
+    the Universe should be considered as a possible explanation for the
+    observed deviation, rather than some systematic (redshift-dependent)
+    effect associated with high-redshift quasars.
+
+Description:
+    Properties of the final quasar sample composed 2421 objects.
+    For each quasar name, equatorial coordinates, redshifts, UV rest-frame
+    monochromatic fluxes at 2500 Angstroem, X-ray rest-frame monochromatic
+    fluxes at 2keV, group numbering for each sub-sample, photon index,
+    distance modulus are given.
+
+File Summary:
+--------------------------------------------------------------------------------
+ FileName      Lrecl  Records   Explanations
+--------------------------------------------------------------------------------
+ReadMe            80        .   This file
+table3.dat       152     2421   Properties of the final quasar sample
+--------------------------------------------------------------------------------
+
+Byte-by-byte Description of file: table3.dat
+--------------------------------------------------------------------------------
+   Bytes Format Units     Label   Explanations
+--------------------------------------------------------------------------------
+   3- 25  A23   ---       Name    Quasar name
+  29- 38  F10.6 deg       RAdeg   Right ascension (J2000.0)
+  40- 50  F11.7 deg       DEdeg   Declination (J2000.0)
+  52- 57  F6.4  ---       z       Redshift
+  61- 69  F9.5  [mW/m2]   logFUV  Rest-frame fluxes at 2500 Angstroem (1)
+  73- 79  F7.5  [mW/m2] e_logFUV  Error on rest-frame fluxes at 2500 Angstroem
+  83- 91  F9.5  [mW/m2]   logFX   Rest-frame fluxes at 2keV (1)
+  95-101  F7.5  [mW/m2] e_logFX   Error on rest-frame fluxes at 2keV
+     105  I1    ---       Group   [1/7] Group numbering for each sub-sample (2)
+ 113-119  F7.5  ---       gammax  Photon index
+ 123-129  F7.5  ---     e_gammax  Error on the photon index
+ 133-141  F9.6  ---       DM      Distance modulus (3)
+ 145-152  F8.6  ---     e_DM      Error on the distance modulus
+--------------------------------------------------------------------------------
+Note (1): Fluxes are in units of log(erg/s/cm^2^)
+Note (2): The Group column flags the different subsamples as follows:
+           1 = XMM-Newton z~3 sample
+           2 = new XMM-Newton z~4 quasar
+           3 = High-z sample
+           4 = XXL
+           5 = SDSS - 4XMM
+           6 = SDSS - Chandra
+           7 = local AGN
+Note (3): The column DM reports the distance moduli to reproduce Fig.9
+--------------------------------------------------------------------------------
+
+Acknowledgements:
+   Elisabeta Lusso, elisabeta.lusso(at)unifi.it
+
+References:
+   Lusso & Risaliti,    Paper I     2017A&A...602A..79L
+   Salvestrini et al.,  Paper II    2019A&A...631A.120S
+
+================================================================================
+(End)                                        Patricia Vannier [CDS]  21-Aug-2020