Could the Milky Way’s Black Hole Hide a Jet?

A new analysis of the supermassive black hole at the heart of the Milky Way, Sagittarius A* (Sgr A*), suggests it may have a hidden jet—a smaller counterpart to the jets produced by more massive and active black holes. These findings, based on data from the Event Horizon Telescope (EHT), show striking similarities between Sgr A* and larger black holes like M87*, which famously has an observable jet.

Unveiling the Structure of Sgr A*

Sgr A*, located 27,000 light-years from Earth, is about 4 million times the mass of the Sun. It was long thought to be relatively quiet, with weak magnetic fields compared to more active black holes. However, the EHT team has now revealed a surprising spiral polarization pattern in the light around Sgr A*. Polarization, a property describing how light waves are oriented, reflects the structure of the black hole’s magnetic field. The well-organized spiral structure around Sgr A* suggests that its magnetic field could potentially funnel material into a jet.

Why Does This Matter?

Jets are critical features of black holes that expel gas and energy at near-light speeds, significantly influencing the evolution of their host galaxies. The presence of a jet in Sgr A* would indicate that:

1. Jets may be more common than previously believed, even in galaxies not currently classified as “active.”
2. Theoretical models of black holes and galaxy evolution might need updates to account for jets in less massive or dormant galaxies like the Milky Way.

While previous studies hinted at jet activity in Sgr A*, direct imaging of such a jet remains elusive. Dr. Angelo Ricarte, one of the study’s leaders, notes that detecting such a feature could reshape how we understand black hole behavior across the cosmos.

Challenges in Observing Sgr A*

Unlike M87*, which is far larger and more stable, Sgr A* is dynamic and changes appearance rapidly, much like a turbulent tornado compared to a steady hurricane. This variability made it far harder for the EHT team to analyze polarization data. Yet, through advanced imaging techniques and simulations, researchers confirmed the existence of the orderly spiral structure.

What’s Next?

The EHT team aims to confirm the presence of a jet in Sgr A* within the next two years, leveraging upgrades to their telescope network, including the Next Generation Event Horizon Telescope (ngEHT). The new array will enable “black hole cinema,” capturing dynamic movies of black holes, their magnetic fields, and potential jets in unprecedented detail.

Broader Implications

The discovery of a hidden jet in Sgr A* could impact cosmological theories, as jets are key players in regulating star formation within galaxies. The energy jets release can heat gas reservoirs, preventing them from collapsing to form new stars. If such jets exist in Sgr A*, it would challenge current assumptions that only more massive black holes, like M87*, possess this capability.

The ongoing exploration of Sgr A* promises not only to reveal more about our galactic backyard but also to deepen our understanding of black holes’ role in shaping the universe.