Imagine a colossal storm erupting just outside a supermassive black hole: this is exactly what Resolve, the new ultra-high-resolution X-ray spectrometer aboard the XRISM satellite, has revealed. The mission is led by the Japanese space agency JAXA, with participation from NASA (United States) and ESA (Europe).
Thanks to XRISM’s extremely precise data, it was possible – for the first time – to identify five distinct components of this wind at the heart of the quasar PDS 456, each one expelled from the central black hole at relativistic speeds, between 20% and 30% of the speed of light.
To put that into perspective, the most violent storms on Earth – such as a category 5 hurricane – reach a maximum speed of about 300 km/h. This “cosmic storm” is millions of times faster.
The study, born out of this international collaboration (JAXA, NASA, ESA) within the XRISM mission, also involved researchers from the University of Rome Tor Vergata and the National Institute for Astrophysics (INAF). It was recently published in the international journal Nature, in an article titled "Structured ionized winds shooting out from a quasar at relativistic speeds", which highlights the discovery of five distinct plasma streams emerging from the accretion disk of the central black hole at extreme velocities of 20–30% the speed of light.
“Our group played a key role in interpreting these data, thanks to advanced X-ray spectroscopic techniques and innovative theoretical models for the physics of black hole-driven winds. These results open a new window on the study of the extreme universe and lay the groundwork for a better understanding of how black holes influence the evolution of galaxies,” says Francesco Tombesi, associate professor of Astrophysics at the Department of Physics of the University of Rome Tor Vergata and INAF associate.
As an XRISM Guest Scientist selected by ESA (one of only two in Italy, along with James Reeves, also an INAF associate), Tombesi contributed to the planning and analysis of the observation of PDS 456, the most luminous quasar in the local universe, using the new high-resolution spectrometer Resolve.
“Rome Tor Vergata played a leading role,” Tombesi continues, “also thanks to the contribution of two young researchers trained within our university: Pierpaolo Condò, a second-year PhD student in Astronomy, Astrophysics and Space Science (AASS), and Alfredo Luminari, a postdoctoral researcher at INAF and former AASS PhD student.”
Such immense energy and complex structure revolutionize our understanding of the extreme environment around supermassive black holes and seriously challenge current models of black hole–galaxy feedback.
“Theories accepted so far,” Tombesi concludes, “fail to explain such a combination of power and fragmentation: clearly, new models are needed to describe these cosmic monsters.”
“PDS 456 is a valuable laboratory for studying the powerful winds produced by supermassive black holes in the local universe. This new observation has allowed us to measure the geometry and velocity distribution of the wind with a level of detail unimaginable before the arrival of XRISM,” adds Valentina Braito, INAF researcher in Milan.
A decisive role in the PDS 456 observation campaign was once again played by the Neil Gehrels Swift Space Observatory, a NASA satellite with significant participation from INAF and the Italian Space Agency (ASI). It was thanks to an observing program with Swift – secured by Valentina Braito – that the team was able to develop the specific models for PDS 456 used in the analysis of XRISM data.
