The XXL Survey: XXII. The XXL-North spectrophotometric sample and galaxy stellar mass function in X-ray detected groups and clusters

V. Guglielmo (1) , B. M. Poggianti , B. Vulcani , C. Adami (1) , F. Gastaldello , S. Ettori , S. Fotoupoulou , E. Koulouridis , M. E. Ramos Ceja , P. Giles , S. Mcgee , B. Altieri , I. Baldry , M. Birkinshaw , M. Bolzonella , A. Bongiorno , M. Brown , L. Chiappetti , S. Driver , A. Elyiv , A. Evrard , B. Garilli , M. Grootes , L. Guennou , A. Hopkins , C. Horellou , A. Iovino , C. Lidman , J. Liske , S. Maurogordato , M. Owers , F. Pacaud , S. Paltani , M. Pierre , M. Plionis , T. Ponman , A. Robotham , T. Sadibekova , M. Scodeggio , M. Sereno , V. Smolčić , R. Tuffs , I. Valtchanov , C. Vignali , J. Willis

1 LAM - Laboratoire d'Astrophysique de Marseille

Context. The fraction of galaxies bound in groups in the nearby Universe is high (50% at z 0). Systematic studies of galaxy properties in groups are important in order to improve our understanding of the evolution of galaxies and of the physical phenomena occurring within this environment.
Aims: We have built a complete spectrophotometric sample of galaxies within X-ray detected, optically spectroscopically confirmed groups and clusters (G&C), covering a wide range of halo masses at z ≤ 0.6.
Methods: In the context of the XXL survey, we analyse a sample of 164 G&C in the XXL-North region (XXL-N), at z ≤ 0.6, with a wide range of virial masses (1.24 × 10¹³ ≤ M_500,scal(M_⊙) ≤ 6.63 × 10¹⁴) and X-ray luminosities ((2.27 × 10⁴¹ ≤ L_500,scal^XXL(erg s^-1) ≤ 2.15 × 10⁴⁴)). The G&C are X-ray selected and spectroscopically confirmed. We describe the membership assignment and the spectroscopic completeness analysis, and compute stellar masses. As a first scientific exploitation of the sample, we study the dependence of the galaxy stellar mass function (GSMF) on global environment.
Results: We present a spectrophotometric characterisation of the G&C and their galaxies. The final sample contains 132 G&C, 22 111 field galaxies and 2225 G&C galaxies with r-band magnitude <20. Of the G&C, 95% have at least three spectroscopic members, and 70% at least ten. The shape of the GSMF seems not to depend on environment (field versus G&C) or X-ray luminosity (used as a proxy for the virial mass of the system). These results are confirmed by the study of the correlation between mean stellar mass of G&C members and L_500,scal^XXL. We release the spectrophotometric catalogue of galaxies with all the quantities computed in this work.
Conclusions: As a first homogeneous census of galaxies within X-ray spectroscopically confirmed G&C at these redshifts, this sample will allow environmental studies of the evolution of galaxy properties.

XXL-N spectrophotometric galaxy sample is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/620/A7

Keywords: Astrophysics - Astrophysics of Galaxies; 85A04; X-rays: galaxies: clusters; galaxies: groups: general; galaxies: clusters: general; galaxies: luminosity function; mass function; galaxies: evolution

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

V. Guglielmo, B. M. Poggianti, B. Vulcani, C. Adami, F. Gastaldello, et al.. The XXL Survey: XXII. The XXL-North spectrophotometric sample and galaxy stellar mass function in X-ray detected groups and clusters. Astronomy and Astrophysics - A&A, 2018, 620, ⟨10.1051/0004-6361/201730709⟩. ⟨insu-03666241⟩