| Přispěvatelé: |
Tozzi, P., Pentericci, L., Gilli, R., Pannella, M., Fiore, F., Miley, G., Nonino, M., R??ttgering, H. J. A., Strazzullo, V., Anderson, C. S., Borgani, S., Calabr??, A., Carilli, C., Dannerbauer, H., Di Mascolo, L., Feruglio, C., Gobat, R., Jin, S., Liu, A., Mroczkowski, T., Norman, C., Rasia, E., Rosati, P., Saro, A. |
| Popis: |
Aims. We present an analysis of the 700 ks Chandra ACIS-S observation of the field around the radio galaxy J1140-2629 (the Spiderweb Galaxy) at z = 2.156, focusing on the nuclear activity in the associated large-scale environment.Methods. We identified unresolved X-ray sources in the field down to flux limits of 1.3 x 10(-16) and 3.9 x 10(-16) erg s(-1) cm(-2) in the soft (0.5-2.0 keV) and hard (2-10 keV) band, respectively. We searched for counterparts in the optical, near-infrared, and submillimeter catalogs available in the literature to identify X-ray sources belonging to the protocluster and derived their X-ray properties.Results. We detect 107 X-ray unresolved sources within 5 arcmin (corresponding to 2.5 Mpc) of J1140-2629, among which 13 have optical counterparts with spectroscopic redshift 2.11 < z < 2.20, and 1 source has a photometric redshift consistent with this range. The X-ray-emitting protocluster members are distributed approximately over a similar to 3.2 x 1.3 Mpc(2) rectangular region. An X-ray spectral analysis for all the sources within the protocluster shows that their intrinsic spectral slope is consistent with an average similar to 1.84 +/- 0.04. Excluding the Spiderweb Galaxy, the best-fit intrinsic absorption for five protocluster X-ray members is N-H > 10(23) cm(-2), while another six have upper limits of the order of a few times 10(22) cm(-2). Two sources can only be fitted with very flat Gamma 10.5. This value corresponds to an enhancement factor of 6.0(-3.0)(+9.0) for the nuclear activity with L0.5-10 keV > 4 x 10(43 )erg s(-1 )with respect to the COSMOS field at comparable redshifts and stellar mass range.Conclusions. We conclude that the galaxy population in the Spiderweb protocluster is characterized by enhanced X-ray nuclear activity triggered by environmental effects on megaparsec scales. |
