천문학자들은 우리 은하의 중심에 있는 블랙홀인 궁수자리 A* 주위를 도는 “열점”의 징후를 발견했습니다.

천문학자들은 궁수자리 A* 주위를 도는 ‘열점’의 징후를 발견했으며,[{” attribute=””>black hole at the center of our galaxy, using the Atacama Large Millimeter/submillimeter Array (ALMA). The finding helps us better understand the enigmatic and dynamic environment of our supermassive black hole.

“We think we’re looking at a hot bubble of gas zipping around Sagittarius A* on an orbit similar in size to that of the planet Mercury, but making a full loop in just around 70 minutes. This requires a mind-blowing velocity of about 30% of the speed of light!” says Maciek Wielgus of the Max Planck Institute for Radio Astronomy in Bonn, Germany. He led the study that was published today (September 22, 2022) in the journal Astronomy & Astrophysics.

This shows a still image of the supermassive black hole Sagittarius A*, as seen by the Event Horizon Collaboration (EHT), with an artist’s illustration indicating where the modeling of the ALMA data predicts the hot spot to be and its orbit around the black hole. Credit: EHT Collaboration, ESO/M. Kornmesser (Acknowledgment: M. Wielgus)

The observations were made with ALMA in the Chilean Andes, during a campaign by the Event Horizon Telescope (EHT) Collaboration to image black holes. ALMA is — a radio telescope co-owned by the European Southern Observatory (ESO). In April 2017 the EHT linked together eight existing radio telescopes worldwide, including ALMA, resulting in the recently released first-ever image of Sagittarius A*. To calibrate the EHT data, Wielgus and his colleagues, who are members of the EHT Collaboration, used ALMA data recorded simultaneously with the EHT observations of Sagittarius A*. To the research team’s surprise, there were more clues to the nature of the black hole hidden in the ALMA-only measurements.

천문학자들은 ALMA를 사용하여 우리 은하의 중심에 있는 블랙홀인 궁수자리 A* 주위를 빛의 30% 속도로 공전하는 뜨거운 가스 거품을 발견했습니다.

우연히 우리 은하의 중심에서 X선 ​​에너지의 폭발이나 빛이 방출된 직후 일부 관측이 이루어졌는데, 이는[{” attribute=””>NASA’s Chandra X-ray Observatory. These kinds of flares, previously observed with X-ray and infrared telescopes, are thought to be associated with so-called ‘hot spots’, hot gas bubbles that orbit very fast and close to the black hole.

“What is really new and interesting is that such flares were so far only clearly present in X-ray and infrared observations of Sagittarius A*. Here we see for the first time a very strong indication that orbiting hot spots are also present in radio observations,” says Wielgus, who is also affiliated with the Nicolaus Copernicus Astronomical Center, in Warsaw, Poland and the Black Hole Initiative at Harvard University, USA.

이 비디오는 우리 행성의 중심에 있는 우리 태양보다 400만 배 더 큰 블랙홀인 궁수자리 A* 주위를 도는 뜨거운 가스 거품인 핫 스팟의 애니메이션을 보여줍니다.[{” attribute=””>Milky Way. While the black hole (center) has been directly imaged with the Event Horizon Telescope, the gas bubble represented around it has not: its orbit and velocity are inferred from both observations and models. The team who discovered evidence for this hot spot — using the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner — predicts the gas bubble orbits very close to the black hole, at a distance about five times larger than the black hole’s boundary or “event horizon.”

The astronomers behind the discovery also predict that the hot spot becomes dimmer and brighter as it goes around the black hole, as indicated in this animation. Additionally, they can infer that it takes 70 minutes for the gas bubble to complete an orbit, putting its velocity at an astonishing 30% of the speed of light.

Credit: EHT Collaboration, ESO/L. Calçada (Acknowledgment: M. Wielgus)

“Perhaps these hot spots detected at infrared wavelengths are a manifestation of the same physical phenomenon: as infrared-emitting hot spots cool down, they become visible at longer wavelengths, like the ones observed by ALMA and the EHT,” adds Jesse Vos. He is a PhD student at Radboud University, the Netherlands, and was also involved in this study.

The flares were long thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*, and the new findings support this idea. “Now we find strong evidence for a magnetic origin of these flares and our observations give us a clue about the geometry of the process. The new data are extremely helpful for building a theoretical interpretation of these events,” says co-author Monika Moscibrodzka from Radboud University.

This is the first image of Sgr A*, the supermassive black hole at the center of our galaxy. It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array that linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope. The telescope is named after the event horizon, the boundary of the black hole beyond which no light can escape. Credit: EHT Collaboration

ALMA allows astronomers to study polarized radio emission from Sagittarius A*, which can be used to unveil the black hole’s magnetic field. The team used these observations together with theoretical models to learn more about the formation of the hot spot and the environment it is embedded in, including the magnetic field around Sagittarius A*. Their research provides stronger constraints on the shape of this magnetic field than previous observations, helping astronomers uncover the nature of our black hole and its surroundings.

This image shows the Atacama Large Millimeter/submillimeter Array (ALMA) looking up at the Milky Way as well as the location of Sagittarius A*, the supermassive black hole at our galactic center. Highlighted in the box is the image of Sagittarius A* taken by the Event Horizon Telescope (EHT) Collaboration. Located in the Atacama Desert in Chile, ALMA is the most sensitive of all the observatories in the EHT array, and ESO is a co-owner of ALMA on behalf of its European Member States. Credit: ESO/José Francisco Salgado (josefrancisco.org), EHT Collaboration

The observations confirm some of the previous discoveries made by the GRAVITY instrument at ESO’s Very Large Telescope (VLT), which observes in the infrared. The data from GRAVITY and ALMA both suggest the flare originates in a clump of gas swirling around the black hole at about 30% of the speed of light in a clockwise direction in the sky, with the orbit of the hot spot being nearly face-on.

“In the future, we should be able to track hot spots across frequencies using coordinated multiwavelength observations with both GRAVITY and ALMA — the success of such an endeavor would be a true milestone for our understanding of the physics of flares in the Galactic center,” says Ivan Marti-Vidal of the University of València in Spain, co-author of the study.

Wide-field view of the center of the Milky Way. This visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the center of our Milky Way galaxy. The entire image is filled with vast numbers of stars — but far more remain hidden behind clouds of dust and are only revealed in infrared images. This view was created from photographs in red and blue light and forming part of the Digitized Sky Survey 2. The field of view is approximately 3.5 degrees x 3.6 degrees. Credit: ESO and Digitized Sky Survey 2. Acknowledgment: Davide De Martin and S. Guisard (www.eso.org/~sguisard)

The team is also hoping to be able to directly observe the orbiting gas clumps with the EHT, to probe ever closer to the black hole and learn more about it. “Hopefully, one day, we will be comfortable saying that we ‘know’ what is going on in Sagittarius A*,” Wielgus concludes.

More information

Reference: “Orbital motion near Sagittarius A* – Constraints from polarimetric ALMA observations” by M. Wielgus, M. Moscibrodzka, J. Vos, Z. Gelles, I. Martí-Vidal, J. Farah, N. Marchili, C. Goddi and H. Messias, 22 September 2022, Astronomy & Astrophysics.
DOI: 10.1051/0004-6361/202244493

The team is composed of M. Wielgus (Max-Planck-Institut für Radioastronomie, Germany [MPIfR]; Nicholas Copernicus Astronomical Centre, 폴란드 과학 아카데미, 폴란드; 미국 하버드 대학의 블랙홀 이니셔티브 [BHI]), M. Moscibrodzka (네덜란드 라드바우드 대학교 천체물리학과) [Radboud]), J. Vos (Radboud), Z. Gelles (천체 물리학 센터 | Harvard & Smithsonian, 미국 및 BHI), I. Martí-Vidal (Universitat de València, Spain), J. Farah (Las Cumbres Observatory, 미국; 대학 캘리포니아, 산타 바바라, 미국), N. Marchili(이탈리아 지역 센터 ALMA, INAF-Istituto di Radioastronomia, Italy 및 MPIfR), C. Goddi(Dipartimento di Fisica, Università degli Studi di Cagliari, 이탈리아 및 Universidade de São Paulo, 브라질), H. Messias(ALMA 합동 천문대, 칠레).

국제 천문학 시설인 Atacama Large Millimeter/submillimeter Array(ALMA)는 ESO, 미국 국립과학재단(NSF) 및 일본 국립자연과학연구소(NINS)가 칠레 공화국과 협력하여 만든 파트너십입니다. ALMA는 회원국을 대신하여 ESO, 캐나다 국립 연구 위원회(NRC) 및 과학 기술부(MOST)와 협력하여 NSF 및 대만의 Academia Sinica(AS)와 협력하여 NINS에서 자금을 지원합니다. 한국천문연구원(KASI). ). ALMA 생성 및 운영은 회원국을 대신하여 ESO가 주도합니다. Associated Universities, Inc.에서 운영하는 NRAO(National Radio Astronomy Observatory)에서 (AUI), 북미를 대신하여; 그리고 동아시아를 대표하여 일본국립천문대(NAOJ)에 의해. JAO(Joint ALMA Observatory)는 ALMA의 건설, 운영 및 운영을 위한 통합 리더십 및 관리를 제공합니다.

유럽 ​​남방 천문대(ESO)는 전 세계 과학자들이 모두의 이익을 위해 우주의 비밀을 발견할 수 있도록 합니다. 우리는 천문학자들이 흥미로운 질문에 답하고 천문학의 마법을 전파하는 데 사용하는 세계적 수준의 지구 관측소를 설계, 건설 및 운영하고 천문학 분야의 국제 협력을 촉진합니다. 1962년에 정부간 기구로 설립된 ESO는 오늘날 16개 회원국(오스트리아, 벨기에, 체코, 덴마크, 프랑스, ​​핀란드, 독일, 아일랜드, 이탈리아, 네덜란드, 폴란드, 포르투갈, 스페인, 스웨덴, 스위스, 영국)을 지원합니다. ), 개최국 칠레 및 전략적 파트너인 호주와 함께. ESO 본부, 방문자 센터 및 천문관인 ESO Supernova는 독일 뮌헨 근처에 있으며, 하늘을 관찰하기 좋은 독특한 조건을 갖춘 칠레의 아타카마 사막에는 망원경이 있습니다. ESO는 La Silla, Paranal 및 Chajnantor의 세 가지 모니터링 사이트를 운영합니다. Paranal에서 ESO는 초대형 망원경과 초대형 망원경 간섭계, 두 대의 적외선 조사 망원경과 VLT 가시광선 조사 망원경을 운영합니다. 또한 Paranal에서 ESO는 세계에서 가장 크고 가장 민감한 감마선 관측소인 South Array Cherenkov Telescope를 호스팅하고 운영할 것입니다. ESO는 국제 파트너와 함께 밀리미터 및 서브밀리미터 범위에서 하늘을 모니터링하는 두 시설인 Chajnantor에서 APEX 및 ALMA를 운영합니다. Paranal 근처의 Cerro Armazones에서 우리는 “하늘에서 가장 큰 눈”인 ESO의 초대형 망원경을 만들고 있습니다. 칠레 산티아고에 있는 사무실에서 우리는 칠레에서의 사업을 지원하고 파트너 및 칠레 커뮤니티와 협력합니다.