MARCHESI, STEFANOSTEFANOMARCHESIMIGNOLI, MarcoMarcoMIGNOLIGILLI, RobertoRobertoGILLIMAZZOLARI, GiovanniGiovanniMAZZOLARISIGNORINI, MatildeMatildeSIGNORINIBRIENZA, MarisaMarisaBRIENZABISOGNI, SusannaSusannaBISOGNIBOLZONELLA, MicolMicolBOLZONELLACUCCIATI, OlgaOlgaCUCCIATID'AMATO, QuirinoQuirinoD'AMATOPECA, ALESSANDROALESSANDROPECAPRANDONI, ISABELLAISABELLAPRANDONITOZZI, PaoloPaoloTOZZIVIGNALI, CRISTIANCRISTIANVIGNALIVITO, FabioFabioVITOCOMASTRI, AndreaAndreaCOMASTRI2024-01-172024-01-1720230004-6361http://hdl.handle.net/20.500.12386/34552We present the results of a spectroscopic campaign with the Multi-Object Double Spectrograph (MODS) instrument mounted on the Large Binocular Telescope (LBT), aimed at obtaining a spectroscopic redshift for seven Chandra J1030 sources with a photometric redshift >=2.7 and optical magnitude r_AB=[24.5-26.5]. We obtained a spectroscopic redshift for five out of seven targets: all of them have z_spec>=2.5, thus probing the reliability of the Chandra J1030 photometric redshifts. The spectroscopic campaign led to the serendipitous discovery of a z~2.78 large scale structure (LSS) in the J1030 field: the structure contains four X-ray sources (three of which were targeted in the LBT-MODS campaign) and two non-X-ray detected galaxies for which a VLT-MUSE spectrum was already available. The X-ray members of the LSS are hosted in galaxies that are significantly more massive (log(M_*/M_sun)=[10.0-11.1]) than those hosting the two MUSE-detected sources (log(M_*/M_sun)<10). Both observations and simulations show that massive galaxies, and particularly objects having log(M_*/M_sun)>10, are among the best tracers of large scale structures and filaments in the cosmic web. Consequently, our result can explain why X-ray-detected AGN have also been shown to be efficient tracers of large scale structures.STAMPAenArticle10.1051/0004-6361/2022455132-s2.0-85160448013https://www.aanda.org/articles/aa/full_html/2023/05/aa45513-22/aa45513-22.htmlttp://arxiv.org/abs/2303.13575v1https://ui.adsabs.harvard.edu/abs/2023A%26A...673A..97M/abstract2023A&A...673A..97MFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation