Supermassive black holes millions or billions of times the mass of our sun exert a heating effect across the outer edges of their home galaxies, according to a study published in The Astrophysical Journal Letters.
How Supermassive Black Holes Heat the Circumgalactic Medium
Galaxies span more than 100,000 light-years and can be more than 100 billion solar masses, dwarfing the central black holes that call them home. Observational data shows that black holes and their surrounding galaxies maintain an intimate connection, traditionally studied primarily in the dense central regions where gas, dust, and stars concentrate. The new research shifts that focus outward to the CGM, the vast region of gas surrounding galaxies that normally cools and falls inward to feed new star creation. Researchers found that while surveys frequently record much of this gas remaining at the galaxy’s outer edges, active black hole jets provide the mechanism that prevents that inflow.
DESI and LoTSS Data Reveal Subtle Jet Interactions
Scientists previously assumed that powerful jets of ionized gas, which carry material outward only along the polar axis of a supermassive black hole, left most circumgalactic material untouched. To test this assumption, a research team led by Namrata Roy examined H-alpha regions around hundreds of galaxies hosting active jets. Utilizing data from the Dark Energy Spectroscopic Instrument (DESI) survey and the LOFAR Two-meter Sky Survey (LoTSS), the authors detected H-alpha emissions—signals indicating hydrogen is warm enough to be ionized—not just close to the jets, but farther away as well. The team also observed an absorption line of magnesium, which indicated a lower overall temperature within the CGM, confirming that the heating is driven directly by the jets.
Did you know? H-alpha emissions are caused by ionized hydrogen, revealing regions of gas warm enough to ionize hydrogen when stimulated by energetic phenomena like black hole jets.
Star Formation Slowed by Galactic Jet Activity
The active jets essentially stir the pot, transferring heat to the circumgalactic material and reducing the amount that falls inward to the galaxy. With less material migrating to the galaxy, fewer stars are born. While other factors drive star production, this study demonstrates that black hole feedback operates through subtle, far-reaching interactions rather than purely destructive central events.
Frequently Asked Questions About Galactic Jets and Star Formation
What specific surveys provided data for The Astrophysical Journal Letters study?
The authors utilized data from the Dark Energy Spectroscopic Instrument (DESI) survey and the LOFAR Two-meter Sky Survey (LoTSS) to analyze hundreds of galaxies with active jets.
How do black hole jets affect hydrogen in the circumgalactic medium?
The light of the jets ionizes regions farther away, heating the CGM and reducing the amount of material that falls inward to form stars.
What element indicated lower temperatures within the CGM?
Researchers examined an absorption line of magnesium, which indicated a lower overall temperature within the CGM.
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