In December 2024, quasar PG 1211+143 found itself in the crosshairs of two X-ray observatories at once: the spectrometers on XRISM and XMM-Newton observed it simultaneously. A quasar is the extremely bright core of a distant galaxy, where a supermassive black hole is accreting surrounding gas. Some of that gas does not fall into the hole but is ejected outward as an ultrafast outflow — at speeds up to 40% of the speed of light.
In X-ray light, this outflow leaves its mark: iron and oxygen atoms absorb light at specific wavelengths, and these "dips" in the spectrum reveal the gas's velocity and density. It turns out the outflow is not uniform. At least three zones are discernible, moving at different speeds—7.4%, 12%, and 33% of the speed of light. The slower zones are denser and cooler, while the faster ones are more tenuous and hotter, like layers of different temperatures in a steam plume above a pot.
This "clumpiness" explains how the black hole accelerates the wind. Simple radiation pressure on free electrons could not impart such speeds to the gas. But if the flow contains dense clumps rich in absorption lines, light pushes on them much more strongly, just as a gust of wind shoves a sail with patches harder than it does smooth fabric. Such clumps are likely what carry matter away from the black hole.
Quasar PG 1211+143 is already the second example where the XRISM X-ray telescope has resolved the clumpy structure of an accretion wind. Previously, the same was seen in quasar PDS 456. It seems that ultrafast outflows from black holes are not smooth rivers but rather billowing jets of steam escaping from a boiling cauldron.
as written by the authors arXiv:2602.16496
The nearby quasar, PG 1211+143, has one of the prototype examples of an ultra fast outflow (UFO), as seen in several past XMM-Newton and Chandra observations. In December 2024, PG 1211+143 was observed simultaneously with XRISM Resolve and XMM-Newton, allowing both the Fe K and soft X-ray outflows to be examined at high resolution simultaneously. The Resolve spectrum revealed a forest of Fe K band absorption lines from the UFO (Mizumoto et al. 2026), comprising of up to six discrete velocity components ranging from $$v/c=-0.074$$ to $$v/c=-0.40$$. Here we present the simultaneous XMM-Newton RGS (Reflection Grating Spectrometer) spectrum, where three lower ionization counterparts of the Fe K velocity zones are observed; at $$v/c=-0.074, -0.12$$ and $$-0.33$$. The soft X-ray absorbers tend to be somewhat less ionized than their Fe K counterparts, with their opacity mainly arising from Fe L shell lines and highly ionized Oxygen. From comparing the Resolve and RGS absorbers, we show that the outflow can be parameterized with a density profile varying with radius as $$r^{-5/3}$$, while the lower ionization zones likely originate from denser clumps of gas. Pure electron scattering appears insufficient to provide enough thrust to power the wind, unless sufficient low ionization gas capable of radiative line driving exists outside of the line of sight. Overall, PG 1211+143 provides further evidence for the clumpy nature of accretion disk winds, as was recently revealed in the quasar PDS 456 with XRISM.
The fastest component of the outflow travels at 120,000 km/s. In one second, such gas would cover the distance from Earth to the Moon and back.