Ultra-Fast Wind from Black Hole in Markarian 817 Detected by XMM-Newton


Markarian 817, a Seyfert 1 galaxy situated in the Draco constellation, is 430 million light-years away from us and has a supermassive black hole at its center. This black hole, with a mass equivalent to 81 million solar masses, is active and plays a crucial role in the galaxy’s evolution.

Supermassive black holes are found at the center of all sizable galaxies, their powerful gravitational pull drawing gas in from their surroundings. This gas spirals inwards, forming a heated, luminous accretion disk around the black hole. Eventually, the gas nearest to the black hole crosses the event horizon, the point of no return, and is consumed. However, only a fraction of the spiraling gas is swallowed by the black hole. Some of it is instead expelled back into space, altering the structure of the galaxy by clearing out the surrounding interstellar gas and hindering the formation of new stars.

Previously, these ultra-fast black hole winds were only identified in extremely luminous accretion disks, which are at their maximum capacity. However, recent observations by the European Space Agency’s (ESA) XMM-Newton spacecraft detected such winds in Markarian 817, a relatively ordinary galaxy. This discovery suggests that these winds are far more common than previously thought, with potentially significant implications for our understanding of how black holes and their host galaxies mutually influence their evolution.

Dr. Miranda Zak, an astronomer at the University of Michigan, likened the process to a fan on a low setting still producing powerful winds. These winds, despite being rare, have enough energy to alter the characteristics of the host galaxy. This process was observed in Markarian 817 for approximately a year, despite the black hole not displaying particularly high activity levels. This phenomenon implies that black holes may have a more substantial impact on their host galaxies than previously thought.

The researchers were initially drawn to Markarian 817 because it had gone quiet in terms of high-energy light emissions, including X-rays. Further observations revealed that ultra-fast winds from the accretion disk were obscuring the X-rays emitted from the black hole’s immediate vicinity. This observation was corroborated by NASA’s NuSTAR telescope, providing further evidence of the central role of black holes in the evolution of galaxies.

This discovery could explain why many galaxies, including the Milky Way, have large central regions with few new stars. This could be due to black hole winds clearing out the gas required for star formation. However, for this to be the case, the winds must be fast enough, last long enough, and be generated by black holes with typical levels of activity.

The study’s findings were published in the Astrophysical Journal Letters and highlight the importance of long, uninterrupted observations in understanding black holes. Dr. Norbert Schartel, the XMM-Newton project scientist, emphasized the crucial role of the XMM-Newton mission in facilitating these observations, noting its high sensitivity and ability to make long, uninterrupted observations.



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