J/MNRAS/521/289 XQR-30 quasars absorption systems properties (Davies+, 2023) ================================================================================ The XQR-30 metal absorber catalogue: 778 absorption systems spanning 2 <~ z <~ 6.5. Davies R.L., Ryan-Weber E., D'odorico V., Bosman S.E.I., Meyer R.A., Becker G.D., Cupani G., Bischetti M., Sebastian A.M., Eilers A.-C., Farina E.P., Wang F., Yang J., Zhu Y. =2023MNRAS.521..289D (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: QSOs ; Intergalactic medium ; Spectroscopy ; Molecular data ; Optical ; Ultraviolet ; Infrared ; Redshifts ; Equivalent widths ; Velocity dispersion ; References Keywords: intergalactic medium - quasars: absorption lines - early Universe Abstract: Intervening metal absorption lines in the spectra of z ~> 6 quasars are fundamental probes of the ionization state and chemical composition of circumgalactic and intergalactic gas near the end of the reionization epoch. Large absorber samples are required to robustly measure typical absorber properties and to refine models of the synthesis, transport, and ionization of metals in the early Universe. The Ultimate XSHOOTER legacy survey of quasars at z ~ 5.8-6.6 (XQR-30) has obtained high signal-to-noise spectra of 30 luminous quasars, nearly quadrupling the existing sample of 12 high quality z ~ 6 quasar spectra. We use this unprecedented sample to construct a catalogue of 778 systems showing absorption in one or more of Mg II (360 systems), Fe II (184), C II (46), C IV (479), Si IV (127), and N V (13) which span 2 <~ z <~ 6.5. This catalogue significantly expands on existing samples of z ~> 5 absorbers, especially for C IV and Si IV which are important probes of the ionizing photon background at high redshift. The sample is 50 per cent (90 per cent) complete for rest-frame equivalent widths W ~> 0.03 {AA} (0.09 {AA}). We publicly release the absorber catalogue along with completeness statistics and a python script to compute the absorption search path for different ions and redshift ranges. This data set is a key legacy resource for studies of enriched gas from the era of galaxy assembly to cosmic noon, and paves the way for even higher redshift studies with JWST and 30 m-class telescopes. Description: High redshift quasars are extremely valuable tools for studying the properties of the Universe during the later stages of the epoch of reionization (z ~ 6). Intervening metal absorption lines in quasar spectra encode the redshift, chemical content, and ionization state of gas in and around galaxies along the line of sight. Over the last decade, the increasing availability of z ~> 6 quasar spectra has propelled our understanding of the Universe during its infancy. Precision measurements of absorber properties at z ~ 6 offer another independent avenue to probe the reionization history of the Universe. Finally, higher ionization species such as C IV and Si IV probe enriched gas in galaxy halos and are therefore a unique tracer of outflows in the early Universe. The Ultimate XSHOOTER legacy survey of quasars at z ~ 5.8-6.6 has obtained 30 high signal-to-noise (S/N; => 10 per 10 km/s spectral pixel at 1285 {AA} rest-frame) quasar spectra with the goal of characterizing the properties of the Universe during the second half of reionization. This ESO large program quadruples the existing sample of 12 archival spectra in the same redshift range observed at comparable S/N and spectral resolution (~ 30 km/s). The combined sample of 42 quasars (hereafter referred to as the 'enlarged XQR-30' or E-XQR-30 sample) provides the largest homogeneous collection of high quality quasar spectra in the early Universe. The catalogue was constructed using a combination of automated line finding, custom filtering algorithms and visual inspection. The majority of the spectra were obtained as part of XQR-30 which acquired deep, medium resolution observations of 30 bright quasars at 5.8 <~ z <~ 6.6 using XSHOOTER. The other 12 spectra were sourced from archival XSHOOTER observations of quasars in the same redshift and magnitude range that have similar spectral resolution and S/N to the XQR-30 spectra. The full sample is described in detail in D'Odorico et al. (2023MNRAS.523.1399D). All 42 quasars were targeted based on their redshift and magnitude, with no prior knowledge of intervening absorber properties. The spectrum data are extracted with reduction process is described in Becker et al. (2019ApJ...883..163B, Cat. J/ApJ/883/163). When fitting the absorption lines it became apparent that some spectra have significantly higher spectral resolution than the nominal value. Concerning redshifts, we adopted the best quasar redshifts that were available when the construction of the absorption line catalogue commenced. The redshifts were taken from emission line measurements where available (primarily [C II] {lambda}158{mu}m as well as CO, Mg II, and Ly{alpha} + N V), or from the apparent start of the Ly{alpha} forest. The tableb1.dat regroups redshifts and spectral resolutions for the 42 quasars. Next as explained in section 3, the absorption line catalogue xqr30abs.dat was constructed by performing an automated search for candidate systems in each spectrum, filtering the list of candidates using a combination of custom algorithms and visual inspection, and fitting Voigt profiles to obtain the column density, Doppler b parameter, equivalent widths and velocity of individual absorption components. Many of the steps use routines from astrocook application for identifying and fitting absorption systems in quasar spectra. We also include Voigt profile fits and continuum spectra for each 42 quasars. The final catalogue contains a total of 778 systems including 479 C IV absorbers, 360 Mg II absorbers, and 46 C II absorbers . More, as described in section 3.2, we provide in tableb2.dat the masked spectral regions used to better identify candidate metal absorption systems. Also, during section 3.1 Continuum normalization, a significant fraction of spectra show BAL features when processing of BAL quasars, we attempt to adjust the continuum fit to follow the BAL troughs because this increases the probability of recovering underlying narrow absorption lines, wavelength spectral regions of BAL signatures are available in tableb4.dat. Finally, as detailled in section 4.1 Overview of results the movie.mp4 presents a visualisation of absorber catalogue where each frame adds data for one additional quasar. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tableb1.dat 47 42 Adopted quasars emission redshifts and spectral resolutions for the XQR-30 and archival E-XQR-30 xqr30abs.dat 96 5512 The full metal absorber catalog containing systems propertie for the 42 quasars sample tableb2.dat 77 26 *Wavelength regions masked when performing the initial automatic search for absorption systems tableb4.dat 138 18 Wavelength regions in which BAL Broad Absorption Line signatures were detected conti/* . 42 PDF files per quasar showing the flux beginning at observed wavelength of quasar Lya emission line, error spectrum, and fitted continuum level voigt/* . 42 PDF files per quasar showing Voigt profile fits for each individual absorption systems movie.mp4 512 405 *This is an animated version of figure 5 of the section 4 as visualisation of absorber catalogue -------------------------------------------------------------------------------- Note on tableb2.dat: The wavelength regions listed in this table were manually masked during the initial system finding due to either strong absorption just redward of the quasar Ly{alpha} emission line preventing the continuum level from being accurately determined, or significant contamination by skylines or telluric absorption (see discussion in Section 3.2). No spectral regions were masked for the 16 quasars not included in this table. Note on movie.mp4: The first frame shows only absorbers detected in the lowest redshift quasar, and each subsequent frame adds data for one additional quasar, sorted in ascending order of redshift. -------------------------------------------------------------------------------- See also: J/MNRAS/502/4009 : Sub-damped Lyman {alpha} systems in XQ-100 II (Berg+, 2021) J/MNRAS/499/5022 : MUSE Analysis of Gas around Galaxies II (Dutta+, 2020) J/MNRAS/485/1961 : List of 22 MEGAFLOW fields (Zabl+, 2019) J/MNRAS/462/3285 : XQ-100. X-shooter quasar spectra (Perrotta+, 2016) J/MNRAS/460/2143 : HI size-mass relation of galaxies (Wang+, 2016) J/MNRAS/435/1198 : z~6 QSOs CIV doublet absorption systems (D'Odorico+,2013) J/ApJ/932/76 : Ly{beta} dark gaps in z<~6 QSOs spectra (Zhu+, 2022) J/ApJ/923/223 : VLT/X-SHOOTER & Keck/ESI spectra of z~5 QSOs (Zhu+, 2021) J/ApJ/883/163 : OI abs. search in Keck and VLT spectra of 199 QSOs (Becker+, 2019) J/ApJ/794/156 : MgII/FeII absorption profile for 0.35.6 quasars follow-up (Banados+, 2016) J/ApJS/221/2 : Keck+Magellan survey for LLSs. III. (Prochaska+, 2015) J/other/Nat/605.244 : XQR-30 quasars sample (Bischetti+, 2022) Byte-by-byte Description of file: tableb1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 15 A15 --- QSO Quasar name identifier 17- 22 F6.4 --- z Emission redshift (z) 24- 28 I5 --- Rvis Spectral resolution for VIS 559.5-1024 nm wavelengths (RVIS) 30- 34 I5 --- Rnir Spectral resolution for NIR 1024-2480 nm wavelengths (RNIR) 36- 43 A8 --- Sample Archival quasars sample name of XSHOOTER either XQR-30 or enlarged E-XQR-30 45- 47 A3 --- r_z Literature reference of the redshift z (Ref) (1) -------------------------------------------------------------------------------- Note (1): Literature references are as follows: 1 = Bosman et al. (2018MNRAS.479.1055B) 2 = Wang et al. (2010ApJ...714..699W) 3 = Zhu et al. (2021ApJ...923..223Z) 4 = D'Odorico et al. (2023MNRAS.523.1399D), 5 = Kurk et al. (2007ApJ...669...32K) 6 = Banados et al. (2016ApJS..227...11B, Cat. J/ApJS/227/11) 7 = Becker et al. (2015MNRAS.447.3402B) 8 = Decarli et al. (2018ApJ...854...97D) 9 = Wang et al. (2013ApJ...773...44W) 10 = Carnall et al. (2015MNRAS.451L..16C) 11 = Carilli et al. (2010ApJ...714..834C) 12 = Eilers et al. (2021ApJ...914...74E) 13 = Wang et al. (2016MNRAS.460.2143W, Cat. J/MNRAS/460/2143) 14 = Venemans et al. (2020ApJ...904..130V) 15 = Yang et al. (2019ApJ...880..153Y) 16 = Reed et al. (2019MNRAS.487.1874R) 17 = Banados et al. (2015ApJ...805L...8B) 18 = Mazzucchelli et al. (2017ApJ...849...91M) We adopted the best redshift measurements that were available when commencing construction of the absorption line catalogue. The redshifts are consistent with those published in D'Odorico et al. (2023MNRAS.523.1399D) to within 300 km/s and these small differences do not have any significant impact on the final data set. The spectral resolution values are estimated using seeing measurements as described in Section 2.2.2. -------------------------------------------------------------------------------- Byte-by-byte Description of file: xqr30abs.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 15 A15 --- QSO Quasar name identifier (QsoID) 17- 18 I2 --- SystID ? System identifier number as described in sect. 3.7 components are grouped into systems following a method similar to that described in D'Odorico et al. (2022MNRAS.512.2389D) (SystemID) (1) 20- 22 A3 --- CompID Absorption component whcih are grouped into system, CompID consisting of a system number and a component label (ComponentID) (2) 24- 30 F7.5 --- z Optical-depth-weighted mean redshift systems or Voigt profile redshift components (z) (3) 32- 41 A10 --- El Ion or species with the associated transition wavelength in nm (Species) 43- 47 F5.3 0.1nm EW ? Rest frame equivalent width measurement (W) 49- 55 F7.3 0.1nm e_EW ? Error of EW (dW) 57 A1 --- f_EW Flag reported for each transition in each system (W_flag) (4) 59- 63 F5.2 [cm-2] logN ? Column density measurement (logN) 65- 68 F4.2 [cm-2] e_logN ? Error of logN (dlogN) 70- 71 A2 --- f_logN Flag reported for both systems and individual components (logN_flag) (5) 73- 75 I3 km/s dv90 ? The velocity interval enclosing 90 per cent of the absorption optical depth as in sect. 3.8 defined in Prochaska & Wolfe (1997ApJ...487...73P) (v90) 77- 81 F5.1 km/s b ? The b Doppler parameter measurement of the absorption (b) 83- 87 F5.1 km/s e_b ? Error of b parameter (db) ? 89- 92 A4 --- Samp Flag of the sample constructed as string flag of Y or N answer to 4 questions (SampleFlags) (6) 94 A1 --- Prim Flag indicating whether the system is part of the primary sample as discussed in section 6.2 (PrimarySample) 96 A1 --- PorI Flag indicating whether the absorption system is proximate P or intervening I (ProximateOrIntervening) (7) -------------------------------------------------------------------------------- Note (1): For each ion in each absorption system, we provide the total log N and {Delta}v90 as well as the total W of each transition. We also list the log N, {Delta}v90 and b parameter of each individual Voigt profile component. Note (2): As explicited in section 3.6, components with the same ID were fit using the same z and b parameter. Note (3): We do not quote errors on the redshifts which are typically on the order of 10^-5^. Note (4): Measurements for ions detected at < 3{sigma} are flagged as upper limits (U). This quantity is not reported for individual components. Note (5): Flag indicate upper limits for ions detected at < 3{sigma}, 'U'), saturated profiles (optical depth {tau}>2; 'S'), and ions for which log N had to be fit for different transitions independently ('M'; as seen in Section 3.6). Note (6): Sample flags indicating whether (a) the system was found by the automatic line finder (Section 3.2) ?, (b) the system was classified as real by at least 3/5 expert checkers (Section 3.5)? , (c) the relevant transitions lie in spectral regions free of significant sky contamination (Section 3.2)? , and (d) the relevant transitions lie in regions free of BAL features (Section 4.3)?. Does the absorption lie outside of masked wavelength regions ? Does the absorption lie outside of BAL regions ? Note (7): As seen in section 3.9, proximate (also known as 'associated' or 'intrinsic') absorbers are traditionally defined to lie within ~ 5000 km/S of the quasar redshift. Due to their close proximity to the quasar, such absorbers may have different ionization states or metal abundance patterns to the underlying absorber population. For this reason, it is important to distinguish between intervening and proximate absorbers when investigating e.g. the evolution of absorber properties over cosmic time. We classify all systems that have velocity offsets between -10000 km/s and +5000 km/S from the quasar redshift as proximate absorbers. However, we note that the data published with this paper enable users to calculate the velocity offset of each absorber and apply a different velocity threshold if desired. -------------------------------------------------------------------------------- Byte-by-byte Description of file: tableb2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 15 A15 --- QSO Quasar name identifier 17- 21 F5.1 nm LyaMin ? Ly{alpha} minimum wavelength of the masked region 23- 27 F5.1 nm LyaMax ? Ly{alpha} maximum wavelength of the masked region 29- 32 I4 nm TellYmin ? Telluric(Y) minimum wavelength of the masked region 34- 37 I4 nm TelYmax ? Telluric(Y) maximum wavelength of the masked region 39- 42 I4 nm TelJ-Hmin ? Telluric(J-H) minimum wavelength of the masked region 44- 47 I4 nm TelJ-Hmax ? Telluric(J-H) maximum wavelength of the masked region 49- 52 I4 nm TelH-Kmin ? Telluric(H-K) minimum wavelength of the masked region 54- 57 I4 nm TelH-Kmax ? Telluric(H-K) maximum wavelength of the masked region 59- 62 I4 nm TelK1min ? First Telluric(K) minimum wavelength of the masked region 64- 67 I4 nm TelK1max ? First Telluric(K) maximum wavelength of the masked region 69- 72 I4 nm TelK2min ? Second Telluric(K) minimum wavelength of the masked region 74- 77 I4 nm TelK2max ? Second Telluric(K) maximum wavelength of the masked region -------------------------------------------------------------------------------- Byte-by-byte Description of file: tableb4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 15 A15 --- QSO Quasar name identifier 17- 19 A3 --- CIV CIV name ion species 21- 38 F18.13 0.1nm CIVwmin Minimum transition wavelength of the CIV 40- 57 F18.13 0.1nm CIVwmax Maximum transition wavelength of the CIV 59- 62 A4 --- SiIV SiIV name ion species 64- 80 F17.13 0.1nm SiIVwmin ? Minimum transition wavelength of the SiIV 82- 99 F18.13 0.1nm SiIVwmax ? Maximum transition wavelength of the SiIV 101-102 A2 --- NV NV name ion species 104-120 F17.13 0.1nm NVwmin ? Minimum transition wavelength of the NV 122-138 F17.13 0.1nm NVwmax ? Maximum transition wavelength of the NV -------------------------------------------------------------------------------- History: From electronic version of the journal License: CC-BY-4.0 ================================================================================ (End) Luc Trabelsi [CDS] 21-May-2026