Black holes, even relatively small ones, leave dramatic “footprints” in space that extend far beyond their immediate vicinity—like ripples from a pebble dropped in a pond. New research using the MeerKAT radio telescope reveals that stellar-mass black holes (those formed from collapsed stars) shoot powerful jets of energy creating massive shockwaves, effectively carving out space and influencing their galactic neighbourhoods over thousands of years. The discoveries show smaller black holes play a much more significant role in shaping galaxies than previously thought. These findings are published today in two studies featured in the scientific journal Astronomy & Astrophysics.
Published by the editorial team, 25 April 2025
New research reveals that the influence of black holes extends far beyond their immediate surroundings, challenging our understanding of these enigmatic objects. While black holes are infamous for compressing matter into an infinitely dense point and warping the very fabric of space and time, their effects may reach farther than previously imagined. Astronomers have uncovered new evidence of how small black holes could shape galaxies, revealing powerful shockwaves driven by high-energy, dark jets. These jets can travel through space for tens of light years after being launched.
Using the MeerKAT radio telescope, the research team has mapped massive bow shock structures caused by the jets from the black holes GRS 1915+105 and Cygnus X-1, providing new insights into the long-term effects of the activity of these systems on their surrounding space. “These discoveries show that stellar black holes can actively sculpt their surroundings, leaving behind enormous shockwaves that tell a story spanning thousands of years,” said Dr. Sara Elisa Motta, astronomer at Istituto Nazionale di Astrofisica (INAF), Italy.
Cygnus X-1, the first stellar-mass black hole ever discovered, has been known to launch powerful jets of high-energy particles that form a massive bow shock structure. This structure is blown by the black hole jets at a distance that is almost three times as big as the black hole-star system. Now, for the first time, MeerKAT has detected such formations in two different radio frequencies, allowing scientists to map them in unprecedented detail. This has revealed previously unseen details in the shock, hinting at multiple jet activity periods that occurred over the past thousands of years, during which the jets interacted with their surroundings at different locations in space. “This is a smoking gun for how black holes influence the space around them,” said Dr. Pikky Atri, astronomer at the Netherlands Institute for Radio Astronomy (ASTRON) and Radboud University. “It’s like a cosmic archaeological dig – each layer of the shock tells a story of past jet eruptions.”
Figures 2.0 and 3.0: Bow shocks of Cyg X-1 (top) and GRS 1915+105 (bottom) as seen by MeerKAT. The edges of the bow shocks are marked in cyan blue.
Meanwhile, astronomers have detected a never-before-seen jet-driven bow shock near GRS 1915+105. The structure, spanning 30 light-years, is evidence of a powerful but unseen jet carving a massive cavity in space. This discovery confirms that the jets from this system are able to significantly impact the black hole’s environment, bridging the gap between theories in the early 2000’s suggesting this bow shock should exist, to finally now detecting it almost two decades later. “We always thought a bow shock around GRS 1915+105 should exist, having seen something similar around Cyg X-1. However, we could not detect it, which led to a lot of confusion. Until MeerKAT discovered the bow shock near GRS 1915+105, scientists started to wonder whether bow shocks could be formed only around some black hole systems,” explained Dr. Sara Elisa Motta.
These findings help explain how even smaller black holes play a major role in shaping galaxies. While supermassive black holes at the centers of galaxies are known to drive large-scale changes, these findings prove that even much smaller, stellar-mass black holes can dramatically reshape their surroundings. Despite being millions of times less massive than their supermassive counterparts, these black holes still leave behind vast, detectable structures—an impact that was previously underestimated.
MeerKAT’s observations suggest that similar shockwaves—remnants of ancient black hole activity—may be hidden throughout our galaxy, waiting to be discovered. Scientists are now actively searching for more of these elusive structures, aiming to map the Milky Way’s hidden black hole history.
The full article, “MeerKAT discovers a jet-driven bow shock near GRS 1915+105”, is available via Astronomy & Astrophysics:
DOI: 10.1051/0004-6361/202452838
URL: https://www.aanda.org/10.1051/0004-6361/202452838
The full article, “Quantifying jet–interstellar medium interactions in Cyg X-1: Insights from dual-frequency bow shock detection with MeerKAT”, is available via Astronomy & Astrophysics:
DOI: 10.1051/0004-6361/202452837
URL: https://www.aanda.org/10.1051/0004-6361/202452837