Optical image from the Kitt Peak telescope showing the dual active galactic nuclei (AGN) system targeted in this proposal, consisting of MCG+04-48-002 and NGC 6921, with NuSTAR high-energy X-ray contours from the previous 2013 observation overlaid in red. The nearby object 2MASX J202837.6+254318, at a similar redshift, is an inactive elliptical galaxy, not detected by NuSTAR, and is not part of this study. This system is the only known dual AGN with both nuclei being this heavily obscured that is spatially resolvable in high-energy X-rays by NuSTAR. Image reproduced from Koss et al. 2016. Download Image
During the past weekend, NuSTAR began a coordinated observing campaign with ESA’s XMM-Newton observatory targeting MCG +04-48-002 and NGC 6921, a nearby pair of galaxies that each host an actively feeding supermassive black hole hidden behind exceptionally thick layers of gas. This is a unique system: it is the only known pair in which both black holes are Compton-thick, or nearly so, and can still be clearly separated by NuSTAR's imaging resolution. Previous X-ray observations show that both sources vary over time, but possibly for different reasons, with changes in obscuration seen in MCG +04-48-002, while NGC 6921 shows strong changes in its intrinsic X-ray brightness. By observing the pair several times over the coming months, NuSTAR and XMM-Newton will use X-ray variability to probe the structure of the obscuring material surrounding the black holes, testing whether individual clouds of gas move across our line of sight, and whether the obscuring structure and variability in this interacting pair differ from those seen in isolated Compton-thick systems. NuSTAR’s high-energy X-ray coverage is especially important for distinguishing changes in obscuration from genuine changes in intrinsic X-ray brightness.
In other news, earlier this month, JPL held its open-house event Explore JPL, inviting over 26,000 members of the public to visit its campus and learn about the spacecraft and robotics JPL has developed, see its mission operations facilities, and discover what its science missions have uncovered about the universe. NuSTAR had a booth as part of JPL's Missions In Flight exhibit, alongside other JPL astrophysics missions such as Roman, SPHEREx, and PRIMA. Several postdocs, students, and staff from the NuSTAR team volunteered for shifts during the event, telling visitors about what X-ray astronomy is, how the NuSTAR telescope works, and what high-energy radiation can tell us about some of the hottest, most extreme places in the universe.
Authors: Alessandro Peca (Postdoctoral Fellow, Universidad Diego Portales, Chile); Hannah Earnshaw (NuSTAR Project Scientist, Caltech)
During the past weekend, NuSTAR began a coordinated observing campaign with ESA’s XMM-Newton observatory targeting MCG +04-48-002 and NGC 6921, a nearby pair of galaxies that each host an actively feeding supermassive black hole hidden behind exceptionally thick layers of gas. This is a unique system: it is the only known pair in which both black holes are Compton-thick, or nearly so, and can still be clearly separated by NuSTAR's imaging resolution. Previous X-ray observations show that both sources vary over time, but possibly for different reasons, with changes in obscuration seen in MCG +04-48-002, while NGC 6921 shows strong changes in its intrinsic X-ray brightness. By observing the pair several times over the coming months, NuSTAR and XMM-Newton will use X-ray variability to probe the structure of the obscuring material surrounding the black holes, testing whether individual clouds of gas move across our line of sight, and whether the obscuring structure and variability in this interacting pair differ from those seen in isolated Compton-thick systems. NuSTAR’s high-energy X-ray coverage is especially important for distinguishing changes in obscuration from genuine changes in intrinsic X-ray brightness.
In other news, earlier this month, JPL held its open-house event Explore JPL, inviting over 26,000 members of the public to visit its campus and learn about the spacecraft and robotics JPL has developed, see its mission operations facilities, and discover what its science missions have uncovered about the universe. NuSTAR had a booth as part of JPL's Missions In Flight exhibit, alongside other JPL astrophysics missions such as Roman, SPHEREx, and PRIMA. Several postdocs, students, and staff from the NuSTAR team volunteered for shifts during the event, telling visitors about what X-ray astronomy is, how the NuSTAR telescope works, and what high-energy radiation can tell us about some of the hottest, most extreme places in the universe.
Authors: Alessandro Peca (Postdoctoral Fellow, Universidad Diego Portales, Chile); Hannah Earnshaw (NuSTAR Project Scientist, Caltech)
