A brand new image from the Event Horizon Telescope (EHT) collaboration — which incorporates scientists from the Center for Astrophysics | Harvard & Smithsonian (CfA) — has uncovered strong and arranged magnetic fields spiraling from the sting of the supermassive black hole Sagittarius A* (Sgr A*). Seen in polarized light for the primary time, this latest view of the monster lurking at the guts of the Milky Way Galaxy has revealed a magnetic field structure strikingly much like that of the black hole at the middle of the M87 galaxy, suggesting that strong magnetic fields could also be common to all black holes. This similarity also hints toward a hidden jet in Sgr A*. The outcomes were published today in The Astrophysical Journal Letters.
Scientists unveiled the primary image of Sgr A* — which is roughly 27,000 light-years away from Earth — in 2022, revealing that while the Milky Way’s supermassive black hole is greater than a thousand times smaller and fewer massive than M87’s, it looks remarkably similar. This made scientists wonder if the 2 shared common traits outside of their looks. To seek out out, the team decided to review Sgr A* in polarized light. Previous studies of sunshine around M87* revealed that the magnetic fields across the black hole giant allowed it to launch powerful jets of fabric back into the encircling environment. Constructing on this work, the brand new images have revealed that the identical could also be true for Sgr A*.
“What we’re seeing now could be that there are strong, twisted, and arranged magnetic fields near the black hole at the middle of the Milky Way galaxy,” said Sara Issaoun, CfA NASA Hubble Fellowship Program Einstein Fellow, Smithsonian Astrophysical Observatory (SAO) astrophysicist, and co-lead of the project. “Together with Sgr A* having a strikingly similar polarization structure to that seen within the much larger and more powerful M87* black hole, we have learned that strong and ordered magnetic fields are critical to how black holes interact with the gas and matter around them.”
Light is an oscillating, or moving, electromagnetic wave that enables us to see objects. Sometimes, light oscillates in a preferred orientation, and we call it “polarized.” Although polarized light surrounds us, to human eyes it’s indistinguishable from “normal” light. Within the plasma around these black holes, particles whirling around magnetic field lines impart a polarization pattern perpendicular to the sphere. This enables astronomers to see in increasingly vivid detail what’s happening in black hole regions and map their magnetic field lines.
“By imaging polarized light from hot glowing gas near black holes, we’re directly inferring the structure and strength of the magnetic fields that thread the flow of gas and matter that the black hole feeds on and ejects,” said Harvard Black Hole Initiative Fellow and project co-lead Angelo Ricarte. “Polarized light teaches us lots more concerning the astrophysics, the properties of the gas, and mechanisms that happen as a black hole feeds.”
But imaging black holes in polarized light is not as easy as putting on a pair of polarized sunglasses, and this is especially true of Sgr A*, which is changing so fast that it doesn’t sit still for pictures. Imaging the supermassive black hole requires sophisticated tools above and beyond those previously used for capturing M87*, a much steadier goal. CfA postdoctoral fellow and SAO astrophysicist Paul Tiede said, “It’s exciting that we were in a position to make a polarized image of Sgr A* in any respect. The primary image took months of intensive evaluation to grasp its dynamical nature and unveil its average structure. Making a polarized image adds on the challenge of the dynamics of the magnetic fields across the black hole. Our models often predicted highly turbulent magnetic fields, making it extremely difficult to construct a polarized image. Fortunately, our black hole is way calmer, making the primary image possible.”
Scientists are excited to have images of each supermassive black holes in polarized light because these images, and the information that include them, provide latest ways to match and contrast black holes of various sizes and much. As technology improves, the photographs are more likely to reveal much more secrets of black holes and their similarities or differences.
Michi Bauböck, postdoctoral researcher on the University of Illinois Urbana-Champaign, said, “M87* and Sgr A* are different in just a few vital ways: M87* is way larger, and it’s pulling in matter from its surroundings at a much faster rate. So, we may need expected that the magnetic fields also look very different. But on this case, they turned out to be quite similar, which can mean that this structure is common to all black holes. A greater understanding of the magnetic fields near black holes helps us answer several open questions — from how jets are formed and launched to what powers the intense flares we see in infrared and X-ray light.”
The EHT has conducted several observations since 2017 and is scheduled to watch Sgr A* again in April 2024. Annually, the photographs improve because the EHT incorporates latest telescopes, larger bandwidth, and latest observing frequencies. Planned expansions for the subsequent decade will enable high-fidelity movies of Sgr A*, may reveal a hidden jet, and will allow astronomers to watch similar polarization features in other black holes. Meanwhile, extending the EHT into space will provide sharper images of black holes than ever before.
The CfA is leading several major initiatives to sharply enhance the EHT over the subsequent decade. The following-generation EHT (ngEHT) project is undertaking a transformative upgrade of the EHT, aiming to bring multiple latest radio dishes online, enable simultaneous multi-color observations, and increase the general sensitivity of the array. The ngEHT expansion will enable the array to make real-time movies of supermassive black holes on event horizon scales. These movies will resolve detailed structure and dynamics near the event horizon, bringing into focus “strong-field” gravity features predicted by General Relativity in addition to the interplay of accretion and relativistic jet-launching that sculpts large-scale structures within the Universe. Meanwhile, the Black Hole Explorer (BHEX) mission concept will extend the EHT into space, producing the sharpest images within the history of astronomy. BHEX will enable the detection and imaging of the “photon ring” — a pointy ring feature formed by strongly lensed emission around black holes. The properties of a black hole are imprinted on the dimensions and shape of the photon ring, revealing masses and spins for dozens of black holes, in turn showing how these strange objects grow and interact with their host galaxies.
The person telescopes involved within the EHT in April 2017, when the observations were conducted, were: the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder Experiment (APEX), the IRAM 30-meter Telescope, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the UArizona Submillimeter Telescope (SMT), the South Pole Telescope (SPT).
Since then, the EHT has added the Greenland Telescope (GLT), which is operated by ASIAA and the CfA, the NOrthern Prolonged Millimeter Array (NOEMA) and the UArizona 12-meter Telescope on Kitt Peak to its network.
