J-PAS/eROSITA Joint Cluster/AGN Survey

The Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) is a narrow band, wide field Cosmological Survey to be carried out from the Javalambre Astrophysical Observatory in Spain with a purpose-built, dedicated 2.5m telescope and a ~5 sq.deg. camera with 1.2 Gpix. Starting in 2019, J-PAS plans to observe >8000sq.deg. of Northern Sky and measure sigma_z~0.003(1+z) photo-z for up to 9E7 LRG and ELG galaxies plus several million QSOs, sampling an effective volume of ~ 14 Gpc^3 up to z~1.3 reaching Stage IV radial BAO experiment. J-PAS is expected to detect ~7E5 galaxy groups and clusters, setting constraints on Dark Energy which rival those obtained from its BAO measurements. J-PAS will have an immense legacy value for almost all astrophysical areas. The key to the J-PAS potential is its innovative approach: a contiguous system of 54 filters with 145A width, placed 100A apart over a multi-degree FoV being a powerful "redshift machine", with the survey speed equivalent to a 4000 multiplexing low resolution spectrograph.eROSITA, to launch early this year, will detect the hot ICM/IGM of up to 1E5 clusters and groups and also will detect systematically all obscured accreting Black Holes in nearby galaxies and many (up to 3 Million) new, distant AGN.J-PAS-eROSITA synergy is optimal in both the studies of AGN and clusters of galaxies. It provides several unique aspects. First, precise measurement of redshift and clean identification. J-PAS data provide immediate identification. Compared to the broad-band photometric surveys, J-PAS is the best way to measure redshifts of AGN, and providing precise enough photo-z for the cluster member galaxies. The uniqueness of J-PAS data in providing the host galaxy properties is particularly interesting for AGN host studies, where narrow-band data are essential. In identifying of galaxy clusters, J-PAS will be uniquely sensitive towards low-mass counterparts, which are missed by the broad-band surveys, enabling cluster cosmology using broad range of cluster masses. Here we present the status of J-PAS, eROSITA and the potential scientific outcomes of the synergy.