Astronomers from the Occasion Horizon Telescope (EHT) collaboration have discovered sturdy magnetic fields spiraling across the supermassive black gap on the heart of our galaxy, named Sagittarius A* (Sgr A*). In 2022, the EHT Collaboration launched the primary picture of Sgr A*, revealing that it seemed similar to the a lot bigger black gap on the heart of Messier 87 galaxy (M87*). This prompted the staff to review Sgr A* in polarized gentle, which helped them examine magnetic fields surrounding the black gap.
Sagittarius A* is positioned 27,000 light-years from Earth and has a mass about 4 million occasions that of the Solar. The Occasion Horizon Telescope noticed the black gap in April 2017. The EHT Collaboration used these observations for each the unique picture from 2022 and the present examine.
“What we’re seeing now could be that there are sturdy, twisted, and arranged magnetic fields close to the black gap on the heart of the Milky Method galaxy,” stated Sara Issaoun of the Middle for Astrophysics | Harvard & Smithsonian, Cambridge, Massachusetts. “Together with Sgr A* having a strikingly related polarization construction to that seen within the a lot bigger and extra highly effective M87* black gap, we’ve realized that sturdy and ordered magnetic fields are crucial to how black holes work together with the fuel and matter round them.”
Location of Sagittarius A* within the Milky Method, imaged in polarized gentle. (Credit score: S. Issaoun, EHT Collaboration)
Due to its distance, learning Sagittarius A* requires extra than simply an extraordinary telescope. The Occasion Horizon Telescope is a world collaboration of radio telescopes linked collectively to function in unison to review black holes. This collaboration successfully creates an Earth-sized digital telescope, which permits astronomers to watch black holes and their environment immediately.
Even with the EHT, learning black holes is tough. The plasma surrounding Sgr A* orbits the black gap in only some minutes, which implies the astronomers couldn’t get a transparent image until they discovered a approach to compensate for that rotation. To generate the primary picture from 2022, the astronomers needed to create a median of hundreds of different photographs that every one precisely match the EHT observations.
What’s extra, the sign is disturbed by interstellar plasma between Earth and the black gap, making it even tougher to review, particularly in polarized gentle.
“As a result of Sgr A* strikes round whereas we attempt to take its image, it was tough to assemble even the unpolarized picture,” stated Geoffrey Bower of the Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan. “We have been relieved that polarized imaging was even doable. Some fashions have been far too scrambled and turbulent to assemble a polarized picture, however nature was not so merciless.”
Similar to the picture from 2022, the newly launched image of Sagittarius A* is generated from a median of a number of datasets obtained from the EHT observations utilizing totally different strategies. To create the ultimate image, the astronomers processed the picture to emphasise areas with sturdy polarization and overlaid it on prime of the picture from 2022.
However how does polarized gentle assist astronomers examine magnetic fields?
When gentle is emitted in scorching, magnetized areas of house, it turns into polarized in a sample perpendicular to the magnetic area strains. Such is the case within the scorching plasma surrounding a black gap. This makes polarized gentle significantly helpful to astronomers fascinated with magnetic fields.
“By imaging polarized gentle from scorching glowing fuel close to black holes, we’re immediately inferring the construction and energy of the magnetic fields that thread the movement of fuel and matter that the black gap feeds on and ejects,” stated Harvard black gap initiative fellow Angelo Ricarte. “Polarized gentle teaches us much more concerning the astrophysics, the properties of the fuel, and mechanisms that happen as a black gap feeds.”
Messier 87* (left) and Sagittarius A* (proper) in polarized gentle, as imaged by the Occasion Horizon Telescope. (Credit score: EHT Collaboration)
The brand new photographs reveal much more similarities Between Sgr A* and M87* than the earlier. An earlier examine of M87* revealed the black gap launched jets of fabric into house and the present outcomes counsel that the identical may be occurring at Sgr A*. Furthermore, the similarities counsel that some processes are related for all black holes, no matter variations in mass and measurement.
“The truth that the magnetic area construction of M87* is so much like that of Sgr A* is critical as a result of it means that the bodily processes that govern how a black gap feeds and launches a jet may be common amongst supermassive black holes, regardless of variations in mass, measurement, and surrounding setting,” stated Mariafelicia De Laurentis of the College of Naples Federico II, Italy. “This consequence permits us to refine our theoretical fashions and simulations, bettering our understanding of how matter is influenced close to the occasion horizon of a black gap.”
The Occasion Horizon Telescope is scheduled to watch Sagittarius A* once more in April, however this time extra telescopes will take part. This permits astronomers to watch the black gap in additional frequencies.
The EHT Collaboration’s findings have been reported in two papers (one and two), printed on March 27 in The Astrophysical Journal Letters.
(Lead picture: Sagittarius A* in polarized gentle as imaged by the Occasion Horizon Telescope. Credit score: EHT Collaboration)
